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Sample records for campi flegrei caldera

  1. Historical activity at Campi Flegrei caldera, southern Italy

    USGS Publications Warehouse

    Dvorak, J.; Gasparini, P.

    1990-01-01

    We cannot forecast whether the activity since 968 will culminate in another eruption or whether Campi Flegrei will remain quiet for several hundred more years. This article summarizes the historical recorded of activity in Campi Flegrei, which, with varying degrees of reliability, spans 2,000 years, and emphasizes that further scientific studies of this caldera will improve our understanding of the behavior of longquiescent volcanic system. 

  2. Secondary hydrothermal mineral system in the Campi Flegrei caldera, Italy

    NASA Astrophysics Data System (ADS)

    Mormone, A.; Piochi, M.; Di Vito, M. A.; Troise, C.; De Natale, G.

    2012-04-01

    Mineral systems generally develop around the deep root of the volcanoes down to the degassing magma chamber due the selective enrichment process of elements within the host-rock. The mineralization process depends on i) volcanic structure, ii) magma and fluid chemistry, iii) host-rock type and texture, iv) temperature and pressure conditions, and v) action timing that affect the transport and precipitation conditions of elements in the solution. Firstly, it generates a hydrothermal system that in a later phase may generate considerable metallogenic mineralization, in terms of both spatial extension and specie abundance. The study of secondary assemblages through depth and, possibly, through time, together with the definition of the general geological, structural, mineralogical and petrological context is the background to understand the genesis of mineral-to-metallogenic systems. We report our study on the Campi Flegrei volcano of potassic Southern Italy belt. It is a sub-circular caldera characterized by an active high-temperature and fluid-rich geothermal system affected by seismicity and ground deformation in the recent decades. The circulating fluids originate at deeper level within a degassing magma body and give rise at the surface up to 1500 tonnes/day of CO2 emissions. Their composition is intermediate between meteoric water and brines. Saline-rich fluids have been detected at ~3000 in downhole. The hydrothermal alteration varies from argillitic to phillitic, nearby the caldera boundary, to propilitic to thermo-metamorphic facies towards its centre. The Campi Flegrei caldera was defined as analogue of mineralized system such as White Island (New Zealand) that is an example of an active magmatic and embryonic copper porphyry system. In order to enhance the knowledge of such a type of embryonic-like metallogenic system, we have carried out macroscopic and microscopic investigations, SEM-EDS and electron microprobe analyses on selected samples from deep wells

  3. Controls on Recent Unrest at Campi Flegrei Caldera, Southern Italy

    NASA Astrophysics Data System (ADS)

    Woo, J.; Bellucci, F.; Kilburn, C. R.; Rolandi, G.

    2005-05-01

    Campi Flegrei, in Southern Italy, is an active caldera that has shown signs of unrest since 1969. Because the caldera has a population of 400,000 people, it is especially important to understand the mechanisms driving the unrest and their implication for the probability of a future eruption. Since its last ignimbrite eruption 12,000 years ago (which produced the Neapolitan Yellow Tuff), volcanic activity in Campi Flegrei has consisted of numerous eruptions (volumes ~0.1 km3 or less) surrounding the inferred caldera rim. For at least the last 3,700 years, the caldera has been subsiding at mean rates of 14-17 mm per year, punctuated by two known periods of mean uplift (1430-1538 and 1969-Present). The first period produced a net uplift of about 30 m at the port of Pozzuoli and was followed in 1538 by the eruption of Monte Nuovo (20 million m3) some 4 km to the west. The second period has to date consisted of two episodes of uplift (in 1969-72 and 1982-84), each raising Pozzuoli by about 2 m. Studies of the second period have attributed uplift either to magmatic intrusion or to the expansion of water in heated aquifers. These interpretations assumed a stationary reference condition. It is here proposed that the reference condition in fact corresponds to subsidence at about 17 mm per year. Slower subsidence then reflects the difference between background subsidence and actual intrusion of magma. The revised interpretation suggests a two-component source for the recent episodes of uplift: (1) intrusion of two batches of magma of ~0.1 km3 that have produced a permanent uplift of about 2.8 m, and (2) the expansion and later dissipation of heated water, which produced a temporary uplift of about 0.7 m that has since disappeared. The similar volumes of recent intrusions and post-NYT eruptions further suggest that Campi Flegrei is fed by discrete batches of magma. The caldera today may thus be underlain by a collection of modest magma bodies rather than a single, large

  4. Tectonic stress and renewed uplift at Campi Flegrei caldera, southern Italy: New insights from caldera drilling

    NASA Astrophysics Data System (ADS)

    Carlino, Stefano; Kilburn, Christopher R. J.; Tramelli, Anna; Troise, Claudia; Somma, Renato; De Natale, Giuseppe

    2015-06-01

    Deep drilling is a key tool for the investigation of active volcanoes in the modern Earth Sciences, as this provides the only means to obtain direct information on processes that occur at depth. Data acquired from drilling projects are fundamental to our understanding of volcano dynamics, and for mitigation of the hazards they pose for millions of people who live close to active volcanoes. We present here the first borehole measurement of the stress field in the crust of Campi Flegrei (southern Italy), a large active caldera, and one of the highest risk volcanoes worldwide. Measurements were performed to depths of ∼500 m during a pilot study for the Campi Flegrei Deep Drilling Project. These data indicate an extensional stress field, with a minimum horizontal stress of ca. 75% to 80% of the maximum horizontal stress, which is approximately equal to the vertical stress. The deviation from lithostatic conditions is consistent with a progressive increase in applied horizontal stress during episodes of unrest, since at least 1969. As the stress field is evolving with time, the outcome of renewed unrest cannot be assessed by analogy with previous episodes. Interpretations of future unrest must therefore accommodate the possibility that Campi Flegrei is approaching conditions that are more favourable to a volcanic eruption than has previously been the case. Such long-term accumulation of stress is not expected to be unique to Campi Flegrei, and so might provide a basis for improved forecasts of eruptions at large calderas elsewhere.

  5. Understanding volcanic hazard at the most populated caldera in the world: Campi Flegrei, Southern Italy

    NASA Astrophysics Data System (ADS)

    De Natale, Giuseppe; Troise, Claudia; Kilburn, Christopher R. J.; Somma, Renato; Moretti, Roberto

    2017-05-01

    Naples and its hinterland in Southern Italy are one of the most urbanized areas in the world under threat from volcanic activity. The region lies within range of three active volcanic centers: Vesuvius, Campi Flegrei, and Ischia. The Campi Flegrei caldera, in particular, has been in unrest for six decades. The unrest followed four centuries of quiescence and has heightened concern about an increased potential for eruption. Innovative modeling and scientific drilling are being used to investigate Campi Flegrei, and the results highlight key directions for better understanding the mechanisms of caldera formation and the roles of magma intrusion and geothermal activity in determining the volcano's behavior. They also provide a framework for evaluating and mitigating the risk from this caldera and other large ones worldwide.

  6. Borehole data to model caldera unrest: the example of Campi Flegrei Deep Drilling Project

    NASA Astrophysics Data System (ADS)

    Carlino, S.; De Natale, G.; Somma, R.; Troise, C.; Kilburn, C.; Tramelli, A.; Troiano, A.; Di Guiseppe, M.; Piochi, M.

    2013-12-01

    To understand the genesis and the physics governing the volcanic area of Campi Flegrei (Southern Italy) a drilling project started on July 2012, in the framework of the International Continental Scientific Drilling Program (ICDP). The Campi Flegrei Deep Drilling Project (CFDDP) schedules two phases: a pilot well, 500 m deep (I phase), and a 3.5 km deeper well (II planned phase), both located within the active resurgent caldera of Campi Flegrei, west to the city of Naples. In this framework new filed data from pilot borehole have been recorded by using a novel procedure of Leak Off Test (LOT). The test has been performed in order to obtain, before the onset of rock failure (which furnishes indication of the minimum principal stress value), a reliable value of in situ permeability. These new data, particularly the actual permeability, are fundamental to calibrate the caldera unrest model at Campi Flegrei and to advance in the quantitative analysis of volcanoes behavior for the assessment of possible future eruptive scenarios. Calderas worldwide are, in fact, characterized by frequent episodes of unrest which, only in few cases, culminate with eruption. This behavior is generally explained in terms of magma intrusion and/or disturbance of geothermal fluids in the shallow crust, which are both source of ground deformations and seismicity. A major goal is, thus, to determine the relative contribution of each process, because the potential for eruptions significantly enhanced if magma movements emerges as the primary component. Here we report the new results of the LOT and its implication in the modeling of Campi Flegrei caldera unrest.

  7. Clues on the origin of post-2000 earthquakes at Campi Flegrei caldera (Italy).

    PubMed

    Chiodini, G; Selva, J; Del Pezzo, E; Marsan, D; De Siena, L; D'Auria, L; Bianco, F; Caliro, S; De Martino, P; Ricciolino, P; Petrillo, Z

    2017-06-30

    The inter-arrival times of the post 2000 seismicity at Campi Flegrei caldera are statistically distributed into different populations. The low inter-arrival times population represents swarm events, while the high inter-arrival times population marks background seismicity. Here, we show that the background seismicity is increasing at the same rate of (1) the ground uplift and (2) the concentration of the fumarolic gas specie more sensitive to temperature. The seismic temporal increase is strongly correlated with the results of recent simulations, modelling injection of magmatic fluids in the Campi Flegrei hydrothermal system. These concurrent variations point to a unique process of temperature-pressure increase of the hydrothermal system controlling geophysical and geochemical signals at the caldera. Our results thus show that the occurrence of background seismicity is an excellent parameter to monitor the current unrest of the caldera.

  8. Progressive approach to eruption at Campi Flegrei caldera in southern Italy

    NASA Astrophysics Data System (ADS)

    Kilburn, Christopher R. J.; de Natale, Giuseppe; Carlino, Stefano

    2017-05-01

    Unrest at large calderas rarely ends in eruption, encouraging vulnerable communities to perceive emergency warnings of volcanic activity as false alarms. A classic example is the Campi Flegrei caldera in southern Italy, where three episodes of major uplift since 1950 have raised its central district by about 3 m without an eruption. Individual episodes have conventionally been treated as independent events, so that only data from an ongoing episode are considered pertinent to evaluating eruptive potential. An implicit assumption is that the crust relaxes accumulated stress after each episode. Here we apply a new model of elastic-brittle failure to test the alternative view that successive episodes promote a long-term accumulation of stress in the crust. The results provide the first quantitative evidence that Campi Flegrei is evolving towards conditions more favourable to eruption and identify field tests for predictions on how the caldera will behave during future unrest.

  9. Progressive approach to eruption at Campi Flegrei caldera in southern Italy.

    PubMed

    Kilburn, Christopher R J; De Natale, Giuseppe; Carlino, Stefano

    2017-05-15

    Unrest at large calderas rarely ends in eruption, encouraging vulnerable communities to perceive emergency warnings of volcanic activity as false alarms. A classic example is the Campi Flegrei caldera in southern Italy, where three episodes of major uplift since 1950 have raised its central district by about 3 m without an eruption. Individual episodes have conventionally been treated as independent events, so that only data from an ongoing episode are considered pertinent to evaluating eruptive potential. An implicit assumption is that the crust relaxes accumulated stress after each episode. Here we apply a new model of elastic-brittle failure to test the alternative view that successive episodes promote a long-term accumulation of stress in the crust. The results provide the first quantitative evidence that Campi Flegrei is evolving towards conditions more favourable to eruption and identify field tests for predictions on how the caldera will behave during future unrest.

  10. Progressive approach to eruption at Campi Flegrei caldera in southern Italy

    PubMed Central

    Kilburn, Christopher R.J.; De Natale, Giuseppe; Carlino, Stefano

    2017-01-01

    Unrest at large calderas rarely ends in eruption, encouraging vulnerable communities to perceive emergency warnings of volcanic activity as false alarms. A classic example is the Campi Flegrei caldera in southern Italy, where three episodes of major uplift since 1950 have raised its central district by about 3 m without an eruption. Individual episodes have conventionally been treated as independent events, so that only data from an ongoing episode are considered pertinent to evaluating eruptive potential. An implicit assumption is that the crust relaxes accumulated stress after each episode. Here we apply a new model of elastic-brittle failure to test the alternative view that successive episodes promote a long-term accumulation of stress in the crust. The results provide the first quantitative evidence that Campi Flegrei is evolving towards conditions more favourable to eruption and identify field tests for predictions on how the caldera will behave during future unrest. PMID:28504261

  11. Long-term magmatic evolution at the Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Forni, Francesca; Bachmann, Olivier; De Astis, Gianfilippo; Mollo, Silvio

    2017-04-01

    Understanding the mechanisms that lead to the accumulation of large silicic upper-crustal magma bodies, potentially resulting in high magnitude caldera-forming eruptions, is fundamental to better constraining volcanic hazard of populous regions on Earth. Campi Flegrei is an excellent example of active and restless volcano, located in a densely populated area, which hosted, during the last 60 ka, two cataclysmic caldera-forming eruptions (Campanian Ignimbrite, 39 ka and Neapolitan Yellow Tuff, 15 ka) and a number of smaller magnitude volcanic events. Here we use detailed petrological data to reconstruct magma storage conditions and understand the past, present and future evolution of the magmatic system at Campi Flegrei. Our data reveal that during the two major eruptions most of the eruptible crystal-poor magma and part of the cumulate crystal mush were efficiently evacuated from the upper crustal reservoir, leading to a caldera collapse. Subsequently, the magmatic reservoir was replenished by more mafic magmas of deeper origin, which evolved through time towards more silicic, colder and more volatile-rich compositions. The most recent eruption at Monte Nuovo (1538 AD), characterized by highly evolved, low temperature and wet magmas akin to those that fed the pre-caldera magmatic activity, suggests that a potentially explosive magma reservoir might be currently present at Campi Flegrei.

  12. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

    PubMed Central

    Di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P.; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

    2016-01-01

    Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common. PMID:27558276

  13. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

    USGS Publications Warehouse

    Di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P.; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

    2016-01-01

    Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

  14. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption.

    PubMed

    Di Vito, Mauro A; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

    2016-08-25

    Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

  15. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

    NASA Astrophysics Data System (ADS)

    di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P.; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

    2016-08-01

    Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

  16. Evidence for fluid migration as the source of deformation at Campi Flegrei caldera (Italy)

    NASA Astrophysics Data System (ADS)

    Battaglia, Maurizio; Troise, Claudia; Obrizzo, Francesco; Pingue, Folco; De Natale, Giuseppe

    2006-01-01

    We model the location, geometry and density of the source of the recent geological unrest at Campi Flegrei caldera (Italy) by inverting levelling, trilateration and gravity measurements collected between 1980 and 1995. The best fitting source for the 1980-84 inflation is a horizontal penny-shaped crack with a density 142 to 1115 kg/m3. The source best fitting the deflation period (1990-95) is a vertical spheroid with density between 902 and 1015 kg/m3. These results exclude the intrusion of magma, and indicate the migration of fluid to and from the caldera hydrothermal system as the cause of ground deformation and consequent unrest.

  17. Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 1. Vent opening maps

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Andrea; Isaia, Roberto; Neri, Augusto; Vitale, Stefano; Aspinall, Willy P.; Bisson, Marina; Flandoli, Franco; Baxter, Peter J.; Bertagnini, Antonella; Esposti Ongaro, Tomaso; Iannuzzi, Enrico; Pistolesi, Marco; Rosi, Mauro

    2015-04-01

    Campi Flegrei is an active volcanic area situated in the Campanian Plain (Italy) and dominated by a resurgent caldera. The great majority of past eruptions have been explosive, variable in magnitude, intensity, and in their vent locations. In this hazard assessment study we present a probabilistic analysis using a variety of volcanological data sets to map the background spatial probability of vent opening conditional on the occurrence of an event in the foreseeable future. The analysis focuses on the reconstruction of the location of past eruptive vents in the last 15 ka, including the distribution of faults and surface fractures as being representative of areas of crustal weakness. One of our key objectives was to incorporate some of the main sources of epistemic uncertainty about the volcanic system through a structured expert elicitation, thereby quantifying uncertainties for certain important model parameters and allowing outcomes from different expert weighting models to be evaluated. Results indicate that past vent locations are the most informative factors governing the probabilities of vent opening, followed by the locations of faults and then fractures. Our vent opening probability maps highlight the presence of a sizeable region in the central eastern part of the caldera where the likelihood of new vent opening per kilometer squared is about 6 times higher than the baseline value for the whole caldera. While these probability values have substantial uncertainties associated with them, our findings provide a rational basis for hazard mapping of the next eruption at Campi Flegrei caldera.

  18. Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Andrea; Flandoli, Franco; Neri, Augusto; Isaia, Roberto; Vitale, Stefano

    2016-11-01

    After the large-scale event of Neapolitan Yellow Tuff ( 15 ka B.P.), intense and mostly explosive volcanism has occurred within and along the boundaries of the Campi Flegrei caldera (Italy). Eruptions occurred closely spaced in time, over periods from a few centuries to a few millennia, and were alternated with periods of quiescence lasting up to several millennia. Often events also occurred closely in space, thus generating a cluster of events. This study had two main objectives: (1) to describe the uncertainty in the geologic record by using a quantitative model and (2) to develop, based on the uncertainty assessment, a long-term subdomain specific temporal probability model that describes the temporal and spatial eruptive behavior of the caldera. In particular, the study adopts a space-time doubly stochastic nonhomogeneous Poisson-type model with a local self-excitation feature able to generate clustering of events which are consistent with the reconstructed record of Campi Flegrei. Results allow the evaluation of similarities and differences between the three epochs of activity as well as to derive eruptive base rate of the caldera and its capacity to generate clusters of events. The temporal probability model is also used to investigate the effect of the most recent eruption of Monte Nuovo (A.D. 1538) in a possible reactivation of the caldera and to estimate the time to the next eruption under different volcanological and modeling assumptions.

  19. RTK DGPS Tecnique Applied to Campi Flegrei Caldera (Southern Italy) Monitoring

    NASA Astrophysics Data System (ADS)

    Pingue, F.; Obrizzo, F.; Pugliano, G.; Sepe, V.; Tammaro, U.

    2005-05-01

    The Campi Flegrei District (Naples - Italy) includes the volcanic areas of the Campi Flegrei and the islands of Ischia and Procida. The Campi Flegrei are characterized from a caldera 35,000 years old (eruption Campanian Ignimbrite) by which numerous volcanic monogenic apparatus developed inside. The last eruption of this caldera rose again in 1538 and carried to the origin of Mount Nuovo. From the geological point of view, the caldera is mainly formed by volcanic rocks and subordinately by clastic sea sediments; from the structural point of view, the configuration of Campi Flegrei is the result of deformations related to the regional and volcano-tectonic events. The regional tectonic is the cause of direct faults with NE-SW and NW-SE direction and subordinately with NS direction. The magmatic chamber is located at low depth (about 4-5 Km). The dynamics of this volcanic field was characterized by slow and continuous vertical movements as well known as Bradyseism. During 1969-72 (maximum uplift 170 cm) and 1982-84 (maximum uplift 184 cm) this area has been interested by two intense episodes with strong uplift of the ground and moderate seismic energy activity. Both the episodes were followed from a phase of subsidence interrupted by modest phenomena of uplifts, the last of which pointed out during the period March-September 2000 (maximum uplift about 4 cm). Even though the two main uplift crises are not culminated into an eruption, it is fundamental considering that these events caused significant damages to the buildings and to the economy of the Campi Flegrei, which has 250,000 inhabitants. The OV-INGV ground deformations studies are also carried out by the application of GPS and precise levelling techniques: in Campi Flegrei area were installed a CGPS network, consisting of 8 permanent stations, and a precise levelling network, consisting of about 300 benchmarks distributed along a distance of 120 km, with a mean distance of about 400 m, on twelve loops. Several

  20. Reconstruction of caldera collapse and resurgence processes in the offshore sector of the Campi Flegrei caldera (Italy)

    NASA Astrophysics Data System (ADS)

    Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

    2015-04-01

    Large collapse calderas are associated with exceptionally explosive volcanic eruptions, which are capable of triggering a global catastrophe second only to that from a giant meteorite impact. Therefore, active calderas have attracted significant attention in both scientific communities and governmental institutions worldwide. One prime example of a large collapse caldera can be found in southern Italy, more precisely in the northern Bay of Naples within the Campi Flegrei Volcanic Area. The Campi Flegrei caldera covers an area of approximately 200 km² defined by a quasi-circular depression, half onland, half offshore. It is still under debate whether the caldera formation was related to only one ignimbritic eruption namely the Neapolitan Yellow Tuff (NYT) eruption at 15 ka or if it is a nested-caldera system related to the NYT and the Campanian Ignimbrite eruption at 39 ka. During the last 40 years, the Campi Flegrei caldera has experienced episodes of unrest involving significant ground deformation and seismicity, which have nevertheless not yet led to an eruption. Besides these short-term episodes of unrest, long-term ground deformation with rates of several tens of meters within a few thousand years can be observed in the central part of the caldera. The source of both short-term and long-term deformation is still under debate and possibly related to a shallow hydrothermal system and caldera resurgence attributed to a deeper magma chamber, respectively. Understanding the mechanisms for unrest and eruptions is of paramount importance as a future eruption of the Campi Flegrei caldera would expose more than 500,000 people to the risk of pyroclastic flows. This study is based on a dense grid (semi-3D) of high-resolution multi-channel seismic profiles acquired in the offshore sector of the Campi Flegrei caldera. The seismic lines show evidence for the escape of fluids and/or gases along weak zones such as faults, thereby supporting the existence of a hydrothermal

  1. The volcanic and geothermally active Campi Flegrei caldera: an integrated multidisciplinary image of its buried structure

    NASA Astrophysics Data System (ADS)

    Piochi, M.; Kilburn, C. R. J.; Di Vito, M. A.; Mormone, A.; Tramelli, A.; Troise, C.; De Natale, G.

    2014-03-01

    The Campi Flegrei caldera in southern Italy is one of the greatest geohazard areas on Earth. Evidence of an active magmatic and geothermal system is provided by ongoing ground uplift, with volcano-tectonic and long-period (LP) seismicity, the persistent degassing of ~1500 tonnes of CO2 per day, the presence of hot fumaroles at temperatures of 90-150 °C, brine-rich aquifers (with total dissolved solids up to 33 g l-1) and high thermal gradients in the crust (with temperatures reaching 420 °C at 3,050 m b.s.l.). Since the 1940s, more than 100 exploratory boreholes have been drilled in the area to depths of 80-3,100 m by the Azienda Geologica Italiana Petroli (AGIP) and the Società Anonima Forze Endogene Napoletane (SAFEN). To date, however, no systematic reanalysis of the drilling data has been carried out, and the buried volcanic structure has not been updated using the most recent scientific results and previous findings. By integrating unpublished data from the AGIP and SAFEN reports with published information from geological, volcanological, petrological, petrophysical and geophysical studies, this paper presents an improved picture of the Campi Flegrei caldera that will be useful for volcanic hazard assessment and mitigation in the Naples area and for future research planning. The results suggest that intra-caldera activity has been influenced by how the magmatic system at depths greater than about 4 km has determined the transfer of magma, volatiles, and heat to the overlying geothermal system and, ultimately, to the surface. In particular, intriguing is that the most volcanically active central-eastern sector of the caldera, which is subject to intense bradyseismic ground movement and gas emission, coincides with a structurally delimited subsurface rock volume characterized by an uprising of the 100 °C isotherm, a deep water supply to the shallower aquifer, the early disappearance of secondary calcite, LP seismicity and high seismic S-wave attenuation. In

  2. Investigating the activity of the Campi Flegrei caldera (Italy) through remote and in situ sensors (Invited)

    NASA Astrophysics Data System (ADS)

    Trasatti, E.; Polcari, M.; Bignami, C.; Bonafede, M.; Buongiorno, F.; Stramondo, S.

    2013-12-01

    Campi Flegrei is a nested caldera in Italy, whose structure includes submerged and continental parts at the western edge of the Bay of Naples. Together with Vesuvius and Etna, it is one of the Italian GeoHazard Supersites. The last eruption took place in 1538 A.D. and since then intense degassing, seismic swarms and several episodes of ground uplift have been observed. The area is characterized by one of the highest volcanic hazard in the world, due to the very high density of inhabitants. A major unrest episode took place in 1982-84, when the town of Pozzuoli, located at the caldera center, was uplifted by 1.80 m (~1 m/yr). During the following decades the area has been generally subsiding but minor uplift episodes of the order of few cm, seismic swarms and degassing episodes took place in 1989, 2000-01 and 2004-06, showing that the caldera is in a critical state on the verge of instability. Since March 1970 leveling surveys were regularly carried out to monitor the elevation changes. In the following decades many efforts have been done to monitor the different aspects of the activity of the area, and nowadays Campi Flegrei is subjected to intense geodetic, geophysical and geochemical monitoring. In the last 30 years a number of geophysical investigations has provided important constraints to the description of the subsurface structure and the historical volcanic activity. Surface deformation, microgravity changes and geochemical anomalies at Campi Flegrei have been interpreted either in terms of instabilities of the hydrothermal system or variations in the magmatic source. In particular, discerning between magmatic vs hydrothermal origin of the source responsible of the large uplift episode during 1982-84 (most probably due to deep magmatic source) and of the mini-uplifts (e.g. 2000 and 2004-06, most probably due to pressure variations in the shallow aquifer) may have important implications in terms of civil protection. In the last two decades, the precise and

  3. The Campi Flegrei Deep Drilling Project: understanding the structure and mechanisms of large collapse calderas

    NASA Astrophysics Data System (ADS)

    de Natale, Giuseppe; Troise, Claudia

    2010-05-01

    Large calderas are the most dangerous volcanoes on the Earth. They are produced by collapse during explosive super-eruptions, which are capable of triggering global catastrophes comparable to large meteorite impacts. The mechanisms of unrest and eruption at calderas are at a large extent unknown and, as demonstrated by volcanological research in the last decades, they may be very different from those characterizing more commonly studied stratovolcanoes. Campi Flegrei caldera (Italy) represents an ideal natural laboratory to fully understand mechanisms of caldera dynamics and to develop techniques for eruption forecast and effective risk mitigation. It is an active volcanic area marked by a quasi-circular caldera depression, formed by huge ignimbritic eruptions. The caldera has recently experienced intense deformation, originating uplift phenomena of more than 3.5 m in 15 years, with maximum rates of 1 m/year in the period 1982-1984, which caused the temporary evacuation of 30,000 people from the centre of Pozzuoli and exposed more than 500,000 to impending eruption risk (several millions in case of an ignimbritic eruption). This area will be the target of a leading International project, the ‘Campi Flegrei Deep Drilling Project', sponsored by ICDP, aimed to study in detail, by a crustal deviated drilling reaching the depth of about 4 km, the deep structure of the caldera. The role of deep drilling at this area is crucial. It could give a fundamental, precise insight into the substructure, the geometry and character of the geothermal systems and their role in the unrest episodes, as well as to explain magma chemistry and the mechanisms of magma-water interaction. One of the main goal will be giving a precise determination of the magma depth, based on the extrapolation of the geothermal gradient in purely conductive conditions, occurring below the maximum aquifer depth. The choice of Campi Flegrei as a target for the deep study of large calderas is justified by the

  4. Rock physics of fibrous rocks akin to Roman concrete explains uplifts at Campi Flegrei Caldera

    NASA Astrophysics Data System (ADS)

    Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

    2015-08-01

    Uplifts in the Campi Flegrei caldera reach values unsurpassed anywhere in the world (~2 meters). Despite the marked deformation, the release of strain appears delayed. The rock physics analysis of well cores highlights the presence of two horizons, above and below the seismogenic area, underlying a coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix that results from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that characterizing the cementitious pastes in modern and Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture.

  5. Helium-3 in subaerial and submarine fumaroles of Campi Flegrei caldera, Italy

    NASA Astrophysics Data System (ADS)

    Tedesco, D.; Allard, P.; Sano, Y.; Wakita, H.; Pece, R.

    1990-04-01

    Helium isotope measurements performed between 1983 and 1988 on subaerial and submarine fumaroles of the Campi Flegrei caldera demonstrate the presence of a mantle component in both types of volcanic gases. The 3He/ 4He ratios plot in a narrow range from 2.0 to 3.2 times the air ratio ( Ra = 1.4 × 10 -6), despite large differences in helium concentrations. Their spatial variation suggests a greater leakage of mantle He in the central part than on the margins of the caldera, consistent with the central distribution of ground deformation and seismicity during the 1982-1984 bradyseismic crisis. In a simple mixing model between upper mantle He ( R/R a ≈ 8 ) and crustal He ( R/R a <- 0.1 ), the proportion of mantle-derived helium in these fluids would amount to ca. 40% at most. Compared to one existing analysis in 1978 (POLYAK and Tolstikhin, 1980), the results on the hottest fumaroles (Solfatara crater) show no evidence of increasing 3He/ 4He during the 1982-1984 events, suggesting no additional input of mantle-magmatic He. However, it is possible that the underlying magma chamber has a low 3He/ 4He ratio, close to the highest ratio measured in the fumaroles, as a result of deep crustal contamination, radioactive aging, and/or past contamination of the local mantle by U- and Th-rich (subducted?) crustal material. All three possibilities are consistent with geochemical data on the local volcanics. If so, the constant 3He/ 4He ratio of Campi Flegrei fumaroles during the 1982-1984 crisis could not be taken as indicative of a non-magmatic origin of the events, which would have important implications with regard to potential eruptive hazards in this area. Future He isotopic investigations on the solid products of Campanian volcanoes should help in settling this question.

  6. Three-dimensional velocity structure and hypocenter distribution in the Campi Flegrei caldera, Italy

    NASA Astrophysics Data System (ADS)

    Aster, R. C.; Meyer, R. P.

    1988-06-01

    The Campi Flegrei (Phlegraean Fields) are dominated by a Quaternary explosive calders, about 10 km in diameter. Within the caldera are numerous later eruptive vents, the last of which formed in 1538 A.D. Well documented local elevation changes of ≈ 10 m have occurred in the caldera since Roman times. Recent inflation of the central caldera began in 1968, after over 400 years of subsidence. During this time more than 2 m of localized uplift occurred, predominantly from 1980 through 1985. Microearthquakes associated with this uplift were recorded by a portable three-component digital network deployed by the University of Wisconsin and the Vesuvius Observatory from August 1983 through May 1984. Those data have been used to obtain detailed information about the velocity structure of the caldera. A best-fit homogeneous half-space model was obtained by a systematic search for optimal residual statistics. A residual-based tomographic technique was applied to isolate a low-seismicity, anomalously-high {v p}/{v s} region in the central caldera, roughly coincident with the region of greatest uplift. Finally, P and S arrival times were used to simultaneously relocate 228 earthquakes and obtain a three-dimensional vp and vs model for the caldera. The results of this velocity study, considered along with drillhole findings, composite fault-plane solutions, and the space-time distribution of earthquakes, suggest that the {v p}/{v s} anomaly may represent an incompetent, highly fractured volume, saturated with liquid water. Hypocenter locations indicate a zone of concentrated seismicity north of the point of highest measured uplift. An inward-dipping elliptical hypocenter pattern suggests a ring fault.

  7. Source and dynamics of a volcanic caldera unrest: Campi Flegrei, 1983-84.

    PubMed

    De Siena, Luca; Chiodini, Giovanni; Vilardo, Giuseppe; Del Pezzo, Edoardo; Castellano, Mario; Colombelli, Simona; Tisato, Nicola; Ventura, Guido

    2017-08-14

    Despite their importance for eruption forecasting the causes of seismic rupture processes during caldera unrest are still poorly reconstructed from seismic images. Seismic source locations and waveform attenuation analyses of earthquakes in the Campi Flegrei area (Southern Italy) during the 1983-1984 unrest have revealed a 4-4.5 km deep NW-SE striking aseismic zone of high attenuation offshore Pozzuoli. The lateral features and the principal axis of the attenuation anomaly correspond to the main source of ground uplift during the unrest. Seismic swarms correlate in space and time with fluid injections from a deep hot source, inferred to represent geochemical and temperature variations at Solfatara. These swarms struck a high-attenuation 3-4 km deep reservoir of supercritical fluids under Pozzuoli and migrated towards a shallower aseismic deformation source under Solfatara. The reservoir became aseismic for two months just after the main seismic swarm (April 1, 1984) due to a SE-to-NW directed input from the high-attenuation domain, possibly a dyke emplacement. The unrest ended after fluids migrated from Pozzuoli to the location of the last caldera eruption (Mt. Nuovo, 1538 AD). The results show that the high attenuation domain controls the largest monitored seismic, deformation, and geochemical unrest at the caldera.

  8. Regional earthquakes followed by delayed ground uplifts at Campi Flegrei Caldera, Italy: Arguments for a causal link

    NASA Astrophysics Data System (ADS)

    Lupi, Matteo; Frehner, Marcel; Weis, Philipp; Skelton, Alasdair; Saenger, Erik H.; Tisato, Nicola; Geiger, Sebastian; Chiodini, Giovanni; Driesner, Thomas

    2017-09-01

    Earthquake-triggered volcanic activity promoted by dynamic and static stresses are considered rare and difficult-to-capture geological processes. Calderas are ideal natural laboratories to investigate earthquake-volcano interactions due to their sensitivity to incoming seismic energy. The Campi Flegrei caldera, Italy, is one of the most monitored volcanic systems worldwide. We compare ground elevation time series at Campi Flegrei with earthquake catalogues showing that uplift events at Campi Flegrei are associated with large regional earthquakes. Such association is supported by (yet non-definitive) binomial tests. Over a 70-year time window we identify 14 uplift events, 12 of them were preceded by an earthquake, and for 8 of them the earthquake-to-uplift timespan ranges from immediate responses to 1.2 yr. Such variability in the response delay may be due to the preparedness of the system with faster responses probably occurring in periods during which the Campi Flegrei system was already in a critical state. To investigate the process that may be responsible for the proposed association we simulate the propagation of elastic waves and show that passing body waves impose high dynamic strains at the roof of the magmatic reservoir of the Campi Flegrei at about 7 km depth. This may promote a short-lived embrittlement of the magma reservoir's carapace otherwise marked by a ductile behaviour. Such failure allows magma and exsolved volatiles to be released from the magmatic reservoir. The fluids, namely exsolved volatiles and/or melts, ascend through a nominally plastic zone above the magmatic reservoir. This mechanism and the associated inherent uncertainties require further investigations but the new concept already implies that geological processes triggered by passing seismic waves may become apparent several months after passage of the seismic waves.

  9. Geochemical Clues on the Processes Controlling the 2005-2014 Unrest at Campi Flegrei Caldera, Italy

    NASA Astrophysics Data System (ADS)

    Chiodini, G.; Vandemeulebrouck, J.; Caliro, S.; D'auria, L.; De Martino, P.; Mangiacapra, A.; Petrillo, Z.

    2014-12-01

    The understanding of the mechanism which triggers unrests at active calderas is one of the most problematic issues of modern volcanology. In particular, magmatic intrusion vs. hydrothermal dynamics is one of the central questions to understand the signals of several restless calderas of the Earth, including, for example, Yellowstone, Long Valley, and Campi Flegrei. Here we focus on Campi Flegrei caldera, sited in the densely inhabited metropolitan area of Napoli, where an inflation stage showing an accelerating trend started in 2005 and reached a maximum vertical displacement of about 24 cm in July 2014. Fumarolic compositions compared with ground deformation data suggests that this ten year's accelerating uplift is mainly caused by the overlapping of two processes: (i) short time pulses caused by injection of magmatic fluids into the hydrothermal system, and (ii) a long time process of heating of the rocks. The short pulses are highlighted by comparing the residuals of ground deformation, fitted with an accelerating curve, with the fumarolic CO2/CH4 and He/CH4 ratios which are good indicators of the arrival of magmatic gases into the hydrothermal system. These two independent datasets show an impressive temporal correlation, with the same sequence of five peaks with a delay of ~ 200 days of the geochemical signal with respect to the geodetic one. The heating of the hydrothermal system is inferred by an evident increase in the fumarolic activity and by temperature-pressure gas-geoindicators. The accelerating ground deformation is paralleled in fact by an increase in the fumarolic CO/CO2 ratio and by a general decrease of the CH4/CO2ratio, both being sign of increased equilibration temperatures. Comparing the observed fumarolic compositions with the thermodynamically derived equilibrium values we infer that the heating is caused by the condensation of increasing amounts of steam. According to a recent interpretation of fumarolic inert gas species, which relates

  10. The Monte Nuovo eruption: the only historical event of the Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    di Vito, Mauro Antonio; Arienzo, Ilenia; Buononato, Salvatore; Civetta, Lucia; Carandente, Antonio; D'Antonio, Massimo; di Renzo, Valeria; Orsi, Giovanni

    2010-05-01

    The Monte Nuovo eruption, the last event of the Campi Flegrei caldera, has been reconstructed through geological, volcanological and petrological investigations, and analyses of historical documents. The eruption, lasted one week and characterised by three vents, included three distinct phases. The main vent (MV) was located in the present crater, whereas two minor vents were along the southern (SV) and north-eastern (NEV) slopes of the Monte Nuovo tuff cone. The sequence of deposits has been subdivided in 5 members named A through E. The eruption began on September 29, 1538, at 7 p.m., and its first and main phase, lasted until the night of September 30. This phase generated almost continuous explosions mainly phreatomagmatic, producing pyroclastic density currents (pdćs) and minor short-lived, low eruption columns, which deposited members A and B. Member A, erupted in about 12 hours through the MV, forms the largest part of the cone. Phreatomagmatic explosions at the SV produced mainly pdćs which deposited Member B only in the southern sector of Monte Nuovo. Strombolian explosions at the SV and NEV deposited Member C over a narrow area. This activity was followed by a pause lasted two days. The eruption resumed on October 3 at 4 p.m. and lasted until the next night. This second phase of the eruption was characterized by a discontinuous sequence of low-energy phreatomagmatic and magmatic explosions at the MV, which deposited Member D. On October 6, at 4 p.m. explosive activity resumed and lasted few hours, mainly with low-energy magmatic explosions of a small dome, grown during the preceding two days, which produced Member E. During this phase 24 people died while climbing the slopes of the newly formed cone. The juvenile products of the Monte Nuovo eruption are phenocryst-poor rocks containing alkali feldspars and subordinate clinopyroxene and Fe-Ti oxides. The are light-coloured pumice and dark scoria fragments, and represent the most evolved magma erupted

  11. Electromagnetic imaging of the deep Campi Flegrei caldera structure (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Giulia Di Giuseppe, Maria; Isaia, Roberto; Patella, Domenico; Piochi, Monica; Troiano, Antonio

    2017-04-01

    The Campi Flegrei caldera (CFc) is the most hazardous volcano in Europe. Enormous investigative efforts have been done aimed to share its inner structure and to understand its unrest dynamics, making the CFc one of the main subjects of interest of modern volcanology. Due to the destructive potential and the active geothermal system, the CFc geological structures have been investigated through many different methodologies. A key role belongs to the applied geophysics that allows to gain knowledge about the volcanic setting and consequently to understand the dynamics of this active caldera system. So far, the main CFc structures have been not yet clearly defined. The strong heterogeneity of the territory associated to the composite coastal morphology and the extreme urbanization represent a major obstacle to apply the geophysical techniques. Therefore the geometry and configuration of the CFc plumbing system are still largely undefined, although seismic surveys nowadays detected findings of melt-bearing rocks, at least locally. Here a deep electromagnetic (EM) imaging the CFc is presented. A Magnetotelluric (MT) profile has been carried out across a 12 km-long transect, ideally intersecting the main recent volcano-tectonic structures. The peculiar sensitivity to subsurface fluids and melts, associated with huge electric conductivity contrasts, make the MT particularly well suited to be applied in active volcanic settings. The obtained results highlight the buried structures down to 10 km of depth providing an interpretative key into the overall caldera dynamics. In particular, the deep magmatic source is revealed, as well as the main ascent pathway of magmatic fluids and the related structures which critically contributing to the shallower-level of deformation at CFc.

  12. Fiber-Reinforced Rocks Akin to Roman Concrete Help Explain Ground Deformation at Campi Flegrei Caldera

    NASA Astrophysics Data System (ADS)

    Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

    2016-04-01

    The caldera of Campi Flegrei is one of the active hydrothermal systems of the Mediterranean region experiencing notable unrest episodes in a densely populated area. During the last crisis of 1982-1984, nearly 40,000 people were evacuated for almost two years from the main town of Pozzuoli, the Roman Puteoli, due to the large uplifts (~2 m over two years) and the persistent seismic activity. The evacuation severely hampered the economy and the social make-up of the community, which included the relocation of schools and commercial shops as well as the harbor being rendered useless for docking. Despite the large uplifts, the release of strain appears delayed. Seismicity begins and reaches a magnitude of 4.0 only upon relatively large uplifts (~ 70-80 cm) contrary to what is generally observed for calderas exhibiting much lower deformation levels. Over and above the specific mechanism causing the unrest and the lack of identification of a shallow magmatic reservoir (< 4 km) by seismic data, there is a core question of how the subsurface rocks of Campi Flegrei withstand a large strain and have high strength. We performed a series of direct measurements on deep well cores by combining high-resolution microstructural and mineralogical analyses with the elastic and mechanical properties of well cores from the deep wells drilled in the area right before the unrest of 1982-1984 - San Vito (SV1 and SV2) and Mofete (MF1, MF2, MF5). The rock physics analysis of the well cores provides evidence for the existence of two horizons, above and below the seismogenic area, underlying a natural, coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix made of intertwining filaments of ettringite and tobemorite, resulting from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that

  13. Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

    NASA Astrophysics Data System (ADS)

    Di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni; Rico, Ciro; Scandone, Roberto; Terrasi, Filippo

    2017-04-01

    Defining and understanding the shallow transfer of magma at volcanoes is crucial to forecast eruptions, possibly the ultimate goal of volcanology. This is particularly challenging at felsic calderas experiencing unrest, which typically includes significant changes in seismicity, deformation and degassing rates. Caldera unrest is particularly frequent, affects wide areas and often does not culminate in an eruption. Moreover its evidence is usually complicated by the presence of a hydrothermal system. As a result, forecasting any eruption and vent-opening sites within a caldera is very difficult. The Campi Flegrei caldera (CFc), in the densely inhabited area of Naples (Italy), is commonly considered one of the most dangerous active volcanic systems. CFc is a 12 km wide depression hosting two nested calderas formed during the eruptions of the Campanian Ignimbrite ( 39 ka) and the Neapolitan Yellow Tuff ( 15 ka). In the last 5 ka, resurgence, with uplift >60 m close to the central part of the caldera, was accompanied by volcanism between 4.8 and 3.8 ka. After 3 ka of quiescence, increasing seismicity and uplift preceded the last eruption at Monte Nuovo in 1538 for several decades. The most recent activity culminated in four unrest episodes between 1950-1952, 1969-1972, 1982-1984 and 2005-Present, with a cumulative uplift at Pozzuoli of 4.5 m; the present unrest episode has been interpreted as being magma-driven. These unrest episodes are considered the most evident expression of a longer-term (centuries or more) restless activity. The post-1980 deformation largely results from a magmatic oblate or sill-like source at 4 km depth below Pozzuoli. Despite the restless activity of CFc, the recent unrest episodes did not culminate in eruption, so that any possibility to define the pre-eruptive shallow transfer of magma remains elusive. Indeed, this definition is a crucial step in order to identify and understand pre-eruptive processes, and thus to make any forecast. To fill

  14. The Project Serapis: High Resolution Seismic Imagingof The Campi Flegrei Caldera Structure

    NASA Astrophysics Data System (ADS)

    Zollo, A.; Virieux, J.; Capuano, P.; Chiarabba, C.; de Franco, R.; Makris, J.; Michelini, A.; Musacchio, G.; Serapis Group

    expected NE-SW and SE-NW structural trends and it has been designed to get 2D/3D images of the crustal structure at a regional scale. A denser 2D network of 35 OBSs has been deployed in the bay of Pozzuoli aimed at detecting and modeling reflected/converted waves from 1 the possible shallow to deep discontinuities beneath the Campi Flegrei caldera. The main target of this particular receiver lay-out is the detailed imaging of the magma chamber top, expected at 4-5 km depth, according to temperature measurements in wells and sparse seismic observations. About 5000 shots have been performed dur- ing the SERAPIS experiment, at an average spatial spacing of 125 m, for a total ship travel path of 620 km. All of the seismic lines have been re-sampled at least twice, using a staggered configuration, which results in a smaller source spacing (less than 65m). In the gulf of Pozzuoli the source array had a geometry of a 5x5 km grid, slightly shifted south with respect to the OBS array. Seismic signals produced by air- guns have been well detected up to 50-60 km distance and the whole Campi Flegrei, Ischia and Procida on-land networks have recorded high quality seismograms pro- duced by the gridded source array in the bay of Pozzuoli. Due to the extended and very dense source and receiver arrays used for SERAPIS, this campaign can provide an innovative contribution to the accurate reconstruction of the Campi Flegrei caldera structure and to the definition of its feeding system at depth. *SERAPIS group: Auger Emmanuel, Bernard Marie-Lise, Bobbio Antonella, Bonagura Mariateresa, Cantore Luciana, Convertito Vincenzo, D'Auria Luca, De Matteis Raffaella, Emolo Anto- nio, Festa Gaetano, Gasparini Paolo, Giberti Grazia, Herrero Andre, Improta Luigi, Lancieri Maria Flora, Nielsen Stefan, Nisii Vincenzo, Russo Guido, Satriano Clau- dio, Simini Mariella, Vassallo Maurizio, Bruno Pier Paolo, Buonocunto Ciro, Capello Marco, Del Pezzo Edoardo, Galluzzo Danilo, Gaudiosi Germana, Giuliana Alessio

  15. Improving Eruption Source Parameter characterization for tephra fallout hazard scenarios at Campi Flegrei caldera (Italy)

    NASA Astrophysics Data System (ADS)

    Mele, Daniela; Isaia, Roberto; Sulpizio, Roberto; Macedonio, Giovanni; Costa, Antonio; Fabio, Dioguardi

    2017-04-01

    Tephra fallout associated with renewal of volcanism at the Campi Flegrei caldera is a serious threat to the Neapolitan area. Previous studies reconstructed probability maps of fall deposits of three different eruption scenarios, representative of past activity: a high-magnitude event similar to the ˜4.5 ka Agnano-Monte Spina eruption, a medium-magnitude event, similar to the ˜4.1 ka Astroni 6 eruption, and a low-magnitude event similar to the ˜4.2 ka Averno2 eruption. A semi-analytical model (HAZMAP) was used to estimate the Eruption Source Parameters (ESP), such as total erupted mass, eruption column height, and Total Grain-Size Distributions (TGSD) associated to these eruptions. ESP were obtained by best-fitting field data of proximal and medial outcrops. However, sensitivity studies of the dispersion of fall deposit showed that TGSD, fine-ash mass and particle aggregation processes are the main cause of the uncertainty. Here we integrate the previous works using new field data including samples of medial-distal outcrops to better reconstruct the TGSD of the reference eruptions. Moreover 3D particle shape parameters obtained by microtomographic technics is used to better characterize drag law and hence particle settling velocity. The new data set is used to feed tephra dispersal models in order to produce a series of maps of tephra loading on the ground for the most representative eruptive scenarios accounting for different meteorological data and the eruptive parameters.

  16. Geochemical clues on the origin of the current accelerating deformation of Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Chiodini, Giovanni

    2016-04-01

    An accelerating process of ground deformation is currently affecting the Campi Flegrei caldera. The deformation pattern is here explained with the overlapping of two processes: short time pulses that are caused by injection of magmatic fluids into the hydrothermal system, and a longer time process of heating of the rock. The short pulses were highlighted by comparing fumarolic compositions and ground deformations. The two independent data sets show the same sequence of anomalous peaks with a delay of ˜ 200 days of the geochemical signal with respect to the geodetic signal. This correspondence strongly support the occurrence of episodes of magmatic fluid injection into the hydrothermal system feeding the fumaroles of Solfatara. Seismic swarms, whose frequency is increasing in the time, accompanies each of this episode. The heating of the hydrothermal system, which parallels the long-period accelerating curve, is inferred by temperature-pressure gas geoindicators. Referring to a recent interpretation that relates variations in the fumarolic inert gas species to open system magma degassing, we infer that the heating is caused by an enrichment in water of the magmatic fluids, in addition to an increment in their flux and an increased frequency of the degassing events. A physical numerical model of the injection of magmatic fluids into the hydrothermal system nicely reproduces many of the observed data including the thermal evolution independently inferred from the fumarolic composition.

  17. Investigation of hydrothermal activity at Campi Flegrei caldera using 3D simulations: extension to high temperature processes

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey; Costa, Antonio; Chiodini, Giovanni

    2015-04-01

    Hydrothermal activity at Campi Flegrei caldera is simulated by using the multiphase code MUFITS (www.mufits.imec.msu.ru). We provide a brief description of the simulator covering the mathematical formulation and its applicability at elevated supercritical temperatures. Then we apply, for the first time, the code to hydrothermal systems investigating the Campi Flegrei caldera case. We consider both shallow subcritical regions and deep supercritical regions of the hydrothermal system. We impose sophisticated boundary conditions at the surface to provide a better description of the reservoir interactions with the atmosphere and the sea. Finally we carry out a parametric study and compare the simulation results with gas temperature and composition, gas and heat fluxes, and temperature measurements in the wells of that area. Results of the parametric study show that flow rate, composition, and temperature of the hot gas mixture injected at depth, and the initial geothermal gradient strongly control parameters monitored at Solfatara. Comparisons with observations show a very good match and suggest that the best guesses for the injected hot (~700 C) fluid mass flow rate is about 50-100 kg/s and the initial geothermal gradient is 120 C/km. Of particular interest resulted the comparison between the simulated thermal profiles and those measured in geothermal wells. Keeping in mind the uncertainties due to the heterogeneities of the system, the good match obtained for the wells in the eastern and north sectors of the caldera (located some km far from Solfatara) suggest that the model can reproduce the gross features of the Campi Flegrei hydrothermal system and implicitly support the hypothesis of a single (or major) deep source of magmatic fluid located close to the centre of the caldera. Surprising results were also obtained by comparing simulated and observed (Agnano well) temperature profiles in a zone close to the gas plume: in this case the simulations clearly suggested

  18. The interplay between deformation and volcanic activity: new data from the central sector of the Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Isaia, Roberto; Sabatino, Ciarcia; Enrico, Iannuzzi; Ernesto, Prinzi; D'Assisi, Tramparulo Francesco; Stefano, Vitale

    2016-04-01

    The new excavation of a tunnel in the central sector of the Campi Flegrei caldera allowed us to collect new stratigraphic and structural data shedding light on the volcano-tectonic evolution of the last 10 ka. The analyzed sequences are composed by an alternation of volcanic, lacustrine, fluvial and marine sediments hosting several deformation structures such as faults, sedimentary dykes and fractures. A review of available well log togheter with the new data were used to perform a 3D reconstruction of paleo-surfaces resulted after the main volcanic and deformation episodes. Results show as the paleo-morphology was strictly controlled by faults and fractures that formed meso-scale channels and depressions subsequently filled by tephra and volcanoclastic sediments. The measured structures indicate an extensional deformation accompanying the ground uplift occurred in various stages of the caldera evolution. Stratigraphic relationships between structures and volcanic deposits further constrain the timing of the deformation phases. Presently an unrest phase of the Campi Flegrei caldera is marked by variations of different parameters such as ground deformation activities well recorded by GPS data, topographic leveling and satellite surveys. The results of this study provide further insight into the long term deformation pattern of the caldera and provide a key to interpret the ground deformation scenarios accompanying a possible resumption of volcanism.

  19. Phase relations and volatiles content of the Minopoli2 Campi Flegrei caldera shoshonitic magma

    NASA Astrophysics Data System (ADS)

    Mangiacapra, A.; Rutherford, M.; Civetta, L.

    2009-04-01

    New constraints on pre-eruption conditions of the Minopoli2 shoshonitic magma are provided by experimental studies. The products of this eruption represent the least evolved magma composition erupted in the first epoch of Campi Flegrei caldera activity (10.3-9.5 ka). Recent geochemical investigations (Mangiacapra et al.,2008)* on dissolved volatiles in the Minopoli2 phenocryst-hosted melt inclusions (MIs), revealed a H2O- and CO2-rich shoshonitic magma, stored at two depths (8-9 and 2-3 km) where it experienced both open-system degassing, driven by crystallization, and flushing with a CO2-rich gas phase coming from deeper levels. Phase equilibrium experiments dry and with 3.5wt% H2O have been guided by the dissolved H2O and CO2 in MIs. The phase equilibria of the shoshonite with 3.5 wt% H2O shows that the observed phenocryst assemblage (olivine, Ca-pyroxene, plagioclase and biotite) becomes stable at 1020±15 °C over the pressure range of 40 to 150 MPa and to higher pressures. The experimental data indicate that the shoshonite crystallised the phenocryst assemblage (15 vol%) at a depth of circa 9 Km and 1025 °C; only small degrees of additional crystallization occurred as the magma ascended to a depth of circa 3 km with degassing of some MIs. Sulphur speciation in glassy MIs was determined as ≥ 79% sulphate which is equivalent to a log fO2≥ NNO + 1.5. The low end of the fO2 range is interpreted to represent the pre-eruption magma at depth. The solubility of CO2 and H2O as a function of pressure in the Minopoli2 shoshonite have been experimentally calibrated. These results contribute to the understanding of magma chamber processes and conduit dynamics, relevant parameters for hazard assessment. * Mangiacapra A., R. Moretti, M. Rutherford, L. Civetta, G. Orsi and P. Papale (2008) The deep magmatic system of the Camp Flegrei caldera (Italy). Geophys. Res. Lett., 35, doi: 10.1029/2008GL035550

  20. Geodetic constraints to the source mechanism of the 2011-2013 unrest at Campi Flegrei (Italy) caldera

    NASA Astrophysics Data System (ADS)

    Trasatti, Elisa; Polcari, Marco; Bonafede, Maurizio; Stramondo, Salvatore

    2016-04-01

    Campi Flegrei (Italy) is a nested caldera and together with Vesuvius is one of the Italian GEO Geohazard Supersites (GSNL). The area is characterized by one of the highest volcanic hazard of the world, due to the very high density of inhabitants (1800/km²), the persistent activity of the system and the explosive character of volcanism. A major unrest episode took place in 1982-84, when the town of Pozzuoli, located at the caldera center, was uplifted by 1.80 m. Minor uplifts of few centimeters, seismic swarms and degassing episodes took place in 1989, 2000 and 2004-06. Since 2005 Campi Flegrei is uplifting, reaching a ground velocity of 9 cm/yr in 2012, showing that the caldera is in a critical state on the verge of instability. In this work, we present results from SAR Interferometry and geodetic data modelling at Campi Flegrei in the framework of the EU's FP7 MED-SUV Project. We exploit two COSMO-SkyMed data sets to map the deformation field during 2011-2013. The spatial distributions of the cumulative displacement from COSMO-SkyMed ascending/descending orbits show similar behaviors, confirming the bell-shaped pattern of the deformation at least within the inner rim of the caldera. The resulting data, together with GPS data from the Neapolitan Volcanoes Continuous GPS network (NeVoCGPS) is fitted through a geophysical inversion process using finite element forward models to account for the 3D heterogeneous medium. The best fit model is a north dipping mixed-mode dislocation source lying at ~5 km depth. The driving mechanism is ascribable to magma input into the source of the large 1982-1984 unrest (since similar source characteristics were inferred) that generates initial inflation followed by additional shear slip accompanying the extension of crack tips. The history and the current state of the system indicate that Campi Flegrei is able to erupt again. Constraining the defomation source may have important implications in terms of civil protection and the

  1. A three-dimensional QP imaging of the shallowest subsurface of Campi Flegrei offshore caldera, southern Italy

    NASA Astrophysics Data System (ADS)

    Serlenga, Vincenzo; Lorenzo, Salvatore; Russo, Guido; Amoroso, Ortensia; Garambois, Stephane; Virieux, Jean; Zollo, Aldo

    2016-11-01

    To improve the knowledge of the shallowest subsurface of Campi Flegrei caldera, a 3-D P wave attenuation tomography of the area was performed. We analyzed about 18,000 active seismic traces, which provided a data set of 11,873 Δt* measurements, e.g., the differential travel times to quality factor ratios. These were inverted through an adapted tomographic inversion procedure. The 3-D tomographic images reveal an average QP about 70, interpreted as water-saturated volcanic and marine sediments. An arc-like, low-QP structure at 0.5-1 km depths was interpreted as a densely fractured, fluid-saturated rock volume, well matching the buried rim of Campi Flegrei caldera. The spatial distribution of high- and low-QP bodies in the inner caldera is correlated with low-Vp values and may reflect either the differences in the percentage of fluid saturation of sediments or the presence of vapor state fluids beneath fumarole manifestations.

  2. Geophysical monitoring of the submerged area of the Campi Flegrei caldera (Southern Italy): experiences and perspectives

    NASA Astrophysics Data System (ADS)

    Iannaccone, Giovanni; Guardato, Sergio; De Martino, Prospero; Donnarumma, Gian Paolo; Bobbio, Antonella; Chierici, Francesco; Pignagnoli, Luca; Beranzoli, Laura

    2016-04-01

    The monitoring system of the Campi Flegrei caldera is made up of a dense geophysical network of seismological and geodetic instruments with data acquired and processed at the Monitoring Center of INGV in Naples. As one third of the caldera is covered by the sea, a marine monitoring system has been operating since 2008 in the center of the gulf of Pozzuoli, where the sea depth is about 100 m at ~2.5 km from the coast. The main component of the monitoring system is CUMAS (Cabled Underwater Multidisciplinary Acquisition System), which consists of a sea floor module equipped with geophysical and oceanographic sensors (broad band seismometer, accelerometer, hydrophone, bottom pressure recorder and single point three component water-current meter) and status and control sensors. CUMAS is connected by cable to the top of an elastic beacon buoy equipped with the power supply and data transmission devices. The buoy consists of a float placed below sea level, surrounding and holding a steel pole that supports a turret structure above sea level. The pole, turret and float system are rigidly connected to the ballast on the sea bottom. Thus a GPS installed on the turret can record the vertical sea floor displacement related to the volcanic activity of the area. The GPS has operated since January 2012 with continuous acquisition lasting more than three years and has recorded a cumulative seafloor uplift of about 7-8 cm. The comparison of the pattern of the GPS buoy data with those of the land stations confirms a quasi-symmetrical vertical displacement field of the caldera area. Measurement of vertical sea floor displacement has also been obtained by the analysis of bottom pressure recorder data. These results, in conjunction with the analysis of seismic and hydrophone data, have encouraged us to extend the marine monitoring system with the deployment in the Gulf of Pozzuoli of three new similar systems. We also present preliminary results of the first few months of activity of

  3. Hydrothermal activity and subsurface soil complexity: implication for outgassing processes at Solfatara crater, Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Montanaro, Cristian; Mayer, Klaus; Scheu, Bettina; Isaia, Roberto; Mangiacapra, Annarita; Gresse, Marceau; Vandemeulebrouck, Jean; Moretti, Roberto; Dingwell, Donald B.

    2016-04-01

    The Solfatara area and its fumaroles are the main surface phenomena of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing which in turn leads to a strong alteration of the volcanic products. Moreover the maar-nature of the crater, and its filling by more recent volcanic deposits, resulted in a complex fractured and multilayered cap to the rising gases. As a consequence the hydrothermal alteration differently affects the rocks within the crater, including pyroclastic fallout ash beds, pyroclastic density current deposits, breccias and lavas. The induced changes in both original microstructure and physical and mechanical properties of the rocks control the outgassing behavior. Here, we report results from a measurement survey conducted in July 2015, and aimed to characterize the in-situ physical (temperature, humidity) and mechanical (permeability, strength, stiffness) properties. The survey also included a mapping of the surficial hydrothermal features and their distributions. Chemical analyses and laboratory measurements (porosity, granulometry) of selected samples were additionally performed. Results show that the crater floor area comprises very different kinds of soils, from fine grained, thin laminated deposits around the two bubbling Fangaia mud pools, to crusted hummock formations along the SE and NE border of the crater. Dry and solid alunite-rich deposits are present in the western and southern part. Furthermore we observed evidences of a beginning of crust formation within the central part of the crater. A large range of surface temperatures, from boiling point to ambient temperature, were measured throughout the surveyed area. Outgassing occurs mainly along the crack system, which has also generated the crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and highly porous sulfur-hardened levels, whereas

  4. Comparison between 3D model of Pisciarelli area (Campi Flegrei caldera) through Terrestrial Laser Scanner

    NASA Astrophysics Data System (ADS)

    Caputo, Teresa; Somma, Renato; Marino, Ermanno; Terracciano, Rosario; Troise, Claudia; De Natale, Giuseppe

    2016-04-01

    The volcanic/geothermal area of Pisciarelli is located within Campi Flegrei caldera .This last is a densely populated area, including the Pozzuoli town and bordering the western side of the Naples city, this causes a high vulnerability and consequently a high volcanic risk. In the recent decades this area has experienced minor ground uplift episodes accompanied by low magnitude seismicity and by strong intensification of degassing activity in particular localized at Pisciarelli area. We present the results of the Terrestrial Laser Scanner (TLS), using a Reigl VZ1000®, analysis of Pisciarelli area performed in June 2013 and the comparison with the data acquired later in March 2014. We apply the TLS technique based on Time of Flight (TOF) method in order to define an accurate 3D digital model for detailed analysis of this area performing numerous scans from different points of view in the area. In this ways was ensured a good coverage of the whole investigated area in order to avoid shaded portion due to the high soil degassing activity. Such fact limits the capacity of laser penetration is caused by wavelength near infrared range. For each survey was obtained a Digital Terrain Model (DTM) from the reconstructed data and both were compared. In particular, we have identified two "critical" areas of interest that will be monitored more frequently. These are: 1) in the lower part of the studied area a major fault line that bounding the Agnano caldera moderately NE-dipping; 2) in the upper part of the study area a zone of depletion with its zone of accumulation. The DTM were georeferenced into the UTM-WGS84 reference frame. The aim of this work is to define a procedure to compare between 3D model applied to monitoring of this area. Also to evaluate of volumetric and morphologic changes and to recognizing unstable masses by comparison of 3D data. For this purpose other TLS surveys will be performed in the upcoming in this active volcanic/geothermal area.

  5. Investigation of hydrothermal activity at Campi Flegrei caldera using 3D numerical simulations: Extension to high temperature processes

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey; Costa, Antonio; Chiodini, Giovanni

    2015-06-01

    Hydrothermal activity at Campi Flegrei caldera is simulated by using the multiphase code MUFITS. We first provide a brief description of the simulator covering the mathematical formulation and its applicability at elevated supercritical temperatures. Then we apply, for the first time, the code to hydrothermal systems investigating the Campi Flegrei caldera case. We consider both shallow subcritical regions and deep supercritical regions of the hydrothermal system. We impose sophisticated boundary conditions at the surface to provide a better description of the reservoir interactions with the atmosphere and the sea. Finally we carry out a parametric study and compare the simulation results with gas temperature and composition, gas and heat fluxes, and temperature measurements in the wells of that area. Results of the parametric study show that flow rate, composition, and temperature of the hot gas mixture injected at depth, and the initial geothermal gradient strongly control parameters monitored at Solfatara. The results suggest that the best guesses conditions for the gas mixture injected at 5 km depth correspond to a temperature of ~ 700 °C, a fluid mass flow rate of about 50-100 kg/s, and an initial geothermal gradient of ~ 120 °C/km.

  6. P-SV conversions at a shallow boundary beneath Campi Flegrei caldera (Italy) - evidence for the magma chamber

    SciTech Connect

    Ferrucci, F.; Hirn, A.; De Natale, G.; Virieux, J.; Mirabile, L. Inst. de Physique du Globe, Paris Osservatorio Vesuviano, Naples CNRS, Inst. de Geodynamique, Valbonne Ist. Universitario Navale, Naples )

    1992-10-01

    Seismograms from an active seismic experiment carried out at Campi Flegrei caldera (near Naples, Italy), show a large-amplitude SV-polarized shear wave, following by less than 1.5-s P waves reflected at wide angle from a deep crustal interface. Early arriving SV-polarized waves, with the same delay to direct P waves, are also observed in seismograms from a regional 280 km-deep, magnitude 5.1 earthquake. Such short delays of S to P waves are consistent with a P-SV conversion on transmission occurring at a shallow boundary beneath the receivers. The large amplitude of the converted-SV phase, along with that the P waves are near vertical, requires a boundary separating a very low rigidity layer from the upper caldera fill. The converted phases are interpreted as a seismic marker of a magma chamber. The top of this magma chamber is located slightly deeper than the deepest earthquakes observed during the 1982-1984 unrest of Campi Flegrei. 8 refs.

  7. 3D time dependent thermo-fluid dynamic model of ground deformation at Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Castaldo, R.; Tizzani, P.; Manconi, A.; Manzo, M.; Pepe, S.; Pepe, A.; Lanari, R.

    2012-04-01

    In active volcanic areas deformation signals are generally characterized by non-linear spatial and temporal variations [Tizzani P. et al., 2007]. This behaviour has been revealed in the last two decades by the so-called advanced DInSAR processing algorithms, developed to analyze surface deformation phenomena [Berardino P. et al., 2002; Ferretti C. et al., 2001]. Notwithstanding, most of the inverse modelling attempts to characterize the evolution of the volcanic sources are based on the assumption that the Earth's crust behaves as a homogeneous linear elastic material. However, the behaviour of the upper lithosphere in thermally anomalous regions (as active volcanoes are) might be well described as a non-Newtonian fluid, where some of the material proprieties of the rocks (i.e., apparent viscosities) can change over time [Pinkerton H. et al., 1995]. In this context, we considered the thermal proprieties and mechanical heterogeneities of the upper crust in order to develop a new 3D time dependent thermo-fluid dynamic model of Campi Flegrei (CF) caldera, Southern Italy. More specifically, according to Tizzani P. et al. (2010), we integrated in a FEM environment geophysical information (gravimetric, seismic, and borehole data) available for the considered area and performed two FEM optimization procedures to constrain the 3D distribution of unknown physical parameters (temperature and viscosity distributions) that might help explaining the data observed at surface (geothermal wells and DInSAR measurements). First, we searched for the heat production, the volume source distribution and surface emissivity parameters providing the best-fit of the geothermal profiles data measured at six boreholes [Agip ESGE, 1986], by solving the Fourier heat equation over time (about 40 kys). The 3D thermal field resulting from this optimization was used to calculate the 3D brittle-ductile transition. This analysis revealed the presence of a ductile region, located beneath the centre of

  8. Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera.

    PubMed

    Pappalardo, Lucia; Mastrolorenzo, Giuseppe

    2012-01-01

    In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.

  9. Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera

    PubMed Central

    Pappalardo, Lucia; Mastrolorenzo, Giuseppe

    2012-01-01

    In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area. PMID:23050096

  10. 4D imaging of the source of ground deformation at Campi Flegrei caldera (Italy) during recent unrest episodes

    NASA Astrophysics Data System (ADS)

    D'Auria, L.; Giudicepietro, F.; Martini, M.; Lanari, R.

    2011-12-01

    Campi Flegrei caldera, has been affected in recent decades by three episodes of significant ground uplift. After the last crisis (1982-84), which was accompanied by strong seismicity, the ground has shown a general descending trend, occasionally interrupted by minor uplift episodes, together with low-magnitude volcano-tectonic and long-period seismicity. We assume that the source of minor ground deformations consists in a diffuse volumetric source, related to both thermoelastic and poroelastic strain. This is a reasonable assumption considering that Campi Flegrei are known to host a geothermal reservoir. We have inverted a DInSAR dataset spanning the interval 1995-2008. Results show that the geometry of the source is much more complex than previously recognized and, most important, it shows significant temporal variations, within few months. The deformation source, of the analyzed uplift episodes, starts with a volumetric expansion centered at a depth of about 5 km. The position of this volume is close to the caldera rims. Later the expansion migrates upward, reaching the surface along preferred paths, leading to the Solfatara area, located almost at the center of the caldera. This area is well known for its powerful geothermal emissions. During the upward migration, seismic long-period sources are activated. Their location is consistent with the path identified by the inversion of the DInSAR dataset. We infer, that this dynamics is linked to the injection of hot fluid batches, along the caldera rims and their upward migration, following preferential high permeability paths. Furthermore we have identified an injection episode which has not been previously recognized. The deformation source remains at depth slowly waning in few years. We show how this conceptual framework fits well with the observed geodetic, seismic and geochemical data.

  11. A three-dimensional QP imaging of the shallowest subsurface of Campi Flegrei offshore caldera, southern Italy

    NASA Astrophysics Data System (ADS)

    Serlenga, Vincenzo; de Lorenzo, Salvatore; Russo, Guido; Amoroso, Ortensia; Virieux, Jean; Garambois, Stephane; Zollo, Aldo

    2017-04-01

    We build a three-dimensional attenuation image of the shallowest subsurface of Campi Flegrei caldera, a resurgent caldera located 15 km west of Naples, southern Italy. Extracting tstar (t*) measurements from an active seismic dataset can be achieved by a spectral ratio method which has been intensively used for earthquakes. The applicability of such measurement has to be validated for active seismic datasets which have a narrower frequency band compared to frequency band of quakes. The validation, as well as the robustness, of such extraction for narrow Ricker source wavelet has been checked through many synthetic and realistic tests. These tests allow us to conclude that this measurement is valid as long as 1) short signal time window are chosen to perform the spectral analysis; 2) the effects caused by heterogeneities of the sampled medium on the seismic spectra have to be taken into account in the description of elastic Green's function. Through such a deconvolution strategy, contributions of the fine velocity structure on signal amplitudes have been significantly removed: in case of suspicious behavior of the spectrum ratio, the measurement is disregarded. This procedure, a kind of deconvolution of the phase propagation imprint, is expected to leave nearly untouched the attenuation signature of seismic traces we are interested in. Such refined measurement approach based on the spectral ratio method has been applied to the real active seismic SERAPIS database providing us a reasonable dataset of 11,873 differential t* measurements (dt*). These data are used for imaging anelastic properties of Campi Flegrei caldera through a linearized, iterative, damped attenuation tomography. Based on configuration of sources and receivers, an attenuating volume as large as 13 x 13 x 1.5 km3 has been imaged. The tomography, with a resolution of 1 km in the horizontal directions and 0.5 km in the vertical direction, allowed to image important features whose reliability has been

  12. Disclosing Multiple Magma Degassing Sources Offers Unique Insights of What's Behind the Campi Flegrei Caldera Unrest

    NASA Astrophysics Data System (ADS)

    Moretti, R.; Civetta, L.; Orsi, G.; Arienzo, I.; D'Antonio, M.; Di Renzo, V.

    2013-12-01

    The definition of the structure and evolution of the magmatic system of Campi Flegrei caldera (CFc), Southern Italy, has been a fundamental tool for the assessment of the short-term volcanic hazard. The ensemble of geophysical and petrologic data show that the CFc magmatic system has been -and still is- characterized by two major reservoirs at different depths. From the deep one (around 8 km), less evolved magmas crystallize and degas, supplying fluids and magmas to the shallow (3-4 km) reservoirs. A thorough reconstruction of processes occurring in magma chamber/s prior and/or during the CFc eruptions has shown that magmas entering shallow reservoirs mixed with resident and crystallized batches. Also the 1982-85 unrest episode has been related to a magma intrusion of 2.1 x 10^7 m^3 at 3-4 km depth, on the basis of geophysical data (ground deformation, gravimetry, seismic imaging) and their interpretation. Thermodynamic evaluation of magma properties, at the time of emplacement, suggests for such an intrusion a bulk density of 2.000 kg/m^3 . Such a value testifies the high amount of exsolved volatiles within the system. The available record of geochemical and isotopic data on surface fumaroles, coupled with melt inclusion data, has already shown that dual (deep and shallow) magma degassing from such two reservoirs, as well as their interaction with the hydrothermal system, allows explaining the relevant fluctuations observed at crater fumaroles after the 1982-85 magma intrusion. An important role was played by the rapid crystallization (around 30 years) of the shallow magma, such that in the recent years gas discharges should be fuelled mostly by the deep magma. Such a process is well recorded in the fumarolic gas composition of the last ~10 years, but has to be reconciled with the unrest dynamics which took place after year 2000, characterized by a slow but continuous ground uplift. All geochemical indicators (major species and noble gases) point to three possible

  13. Anatomy of a caldera: seismic velocity and attenuation models of the Campi Flegrei (Italy).

    NASA Astrophysics Data System (ADS)

    Calò, Marco; Tramelli, Anna

    2017-04-01

    Campi Flegrei is an active Caldera marked by strong vertical deformations of the soil called bradyseisms. The mechanisms proposed to explain this phenomenon are essentially three i) the presence of a shallow magmatic chamber that pushes the lid and consequently producing periodic variation of the soil level, ii) a thermic expansion of the geothermal aquifer due to the periodic increase of heat flux coming from a near magmatic chamber or deep fluids or iii) a combination of both phenomena. To solve the paradox, several models have been proposed to describe the nature and the geometry of the bodies responsible of the bradyseisms. Seismological tools allowed a rough description of the main features in terms of seismic velocities and attenuation parameters and till now were not able to resolve the smallest structures (<1.5-2km) located at shallow depth (0-4 km) and believed to be responsible of the soil deformations. Here we show Vp, Vp/Vs and Qp models carried out by applying an enhanced seismic tomography method combining the double difference approach (Zhang and Thurber, 2003) and the Weighted Average Method (Calò et al., 2009, Calò et al., 2011, 2013). The data used are the earthquakes recorded during the largest bradyseism crisis of the 80's. Our method allowed to image seismic velocity and attenuation structures with linear dimension of 0.5-1.2km, resulting in an improvement of the resolving power at least two times of the other published models (e.g. Priolo et al., 2012). The joint interpretation of seismic velocities and attenuation models allowed to discern small anomalous bodies at shallow depth (0.5-2.0 km) marked by relatively low Vp, high Vp/Vs ratio and low Qp values explainable with the presence of shallow geothermal water saturated reservoir from regions with low Vp, low Vp/Vs and low Qp possibly related to the gas saturated part of the reservoir. At deeper depth (2-3.5 km) bodies with high Vp and Vp/Vs and low Qp can be associated with magmatic

  14. A probabilistic spatial-temporal model for vent opening clustering at Campi Flegrei caldera (Italy)

    NASA Astrophysics Data System (ADS)

    Bevilacqua, A.; Isaia, R.; Flandoli, F.; Neri, A.; Quaranta, D.

    2014-12-01

    Campi Flegrei (CF) is a densely urbanized caldera with a very high volcanic risk. Its more recent volcanic activity was characterized in the last 15 kyrs by more than 70 explosive events of variable scale and vent location. The sequence of eruptive events at CF is remarkably inhomogeneous, both in space and time. Eruptions concentred over periods from a few centuries to a few millennia, and were alternated by periods of quiescence lasting up to several millennia. As a consequence, activity has been subdivided into three distinct epochs, i.e. Epoch I, 15 - 9.5 kyrs, Epoch II, 8.6 - 8.2 kyrs, and Epoch III, 4.8 - 3.7 kyrs BP [e.g. Orsi et al., 2004; Smith et al., 2011]. The eruptive record also shows the presence of clusters of events in space-time, i.e. the opening of a new vent in a particular location and at a specific time seems to increase the probability of another vent opening in the nearby area and in the next decades-centuries (self-exciting effect). Probabilistic vent opening mapping conditional the occurrence of a new event and able to account for some of the intrinsic uncertainties affecting the system, has been investigated in some recent studies [e.g. Selva et al. 2011, Bevilacqua et al. 2014, in preparation], but a spatial-temporal model of the sequence of volcanic activity remains an open issue. Hence we have developed a time-space mathematical model that takes into account both the self-exciting behaviour of the system and the significant uncertainty affecting the eruptive record. Based on the past eruptive record of the volcano, the model allows to simulate sequences of future events as well as to better understand the spatial and temporal evolution of the system. In addition, based on the assumption that the last eruptive event occurred in 1538 AD (Monte Nuovo eruption) is the first event of a new epoch of activity, the model can estimate the probability of new vent opening at CF in the next decades.

  15. A 2-D FEM thermal model to simulate water flow in a porous media: Campi Flegrei caldera case study

    NASA Astrophysics Data System (ADS)

    Romano, V.; Tammaro, U.; Capuano, P.

    2012-05-01

    Volcanic and geothermal aspects both exist in many geologically young areas. In these areas the heat transfer process is of fundamental importance, so that the thermal and fluid-dynamic processes characterizing a viscous fluid in a porous medium are very important to understand the complex dynamics of the these areas. The Campi Flegrei caldera, located west of the city of Naples, within the central-southern sector of the large graben of Campanian plain, is a region where both volcanic and geothermal phenomena are present. The upper part of the geothermal system can be considered roughly as a succession of volcanic porous material (tuff) saturated by a mixture formed mainly by water and carbon dioxide. We have implemented a finite elements approach in transient conditions to simulate water flow in a 2-D porous medium to model the changes of temperature in the geothermal system due to magmatic fluid inflow, accounting for a transient phase, not considered in the analytical solutions and fluid compressibility. The thermal model is described by means of conductive/convective equations, in which we propose a thermal source represented by a parabolic shape function to better simulate an increase of temperature in the central part (magma chamber) of a box, simulating the Campi Flegrei caldera and using more recent evaluations, from literature, for the medium's parameters (specific heat capacity, density, thermal conductivity, permeability). A best-fit velocity for the permeant is evaluated by comparing the simulated temperatures with those measured in wells drilled by Agip (Italian Oil Agency) in the 1980s in the framework of geothermal exploration. A few tens of days are enough to reach the thermal steady state, showing the quick response of the system to heat injection. The increase in the pressure due to the heat transport is then used to compute ground deformation, in particular the vertical displacements characteristics of the Campi Flegrei caldera behaviour. The

  16. The active portion of the Campi Flegrei caldera structure imaged by 3-D inversion of gravity data

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; Russo, Guido; Civetta, Lucia; Orsi, Giovanni; D'Antonio, Massimo; Moretti, Roberto

    2013-10-01

    We present an improved density model and a new structural map of the Neapolitan Yellow Tuff caldera, the active portion of the nested Campi Flegrei caldera. The model was built using a new 3-D inversion of the available high-precision gravity data, and a new digital terrain and marine model. The inversion procedure, based on a variable-depth lumped assembling of the subsurface gravity distribution via cell aggregation, gives better defined insights into the internal caldera architecture, that well agree with the available geological, geophysical, and geochemical data. The adopted 3-D gravity method is highly efficient for characterizing the shallow caldera structure (down to 3 km depth) and defining features related to regional or volcano tectonic lineaments and dynamics. In particular, the resulting density distribution highlights a pronounced density low in correspondence of the central portion of the caldera with a detail not available till now. The joint interpretation of the available data suggests a subsurface structural setting that supports a piecemeal collapse of the caldera, and allows the identification of its headwall. Positive gravity anomalies localize dense intrusions (presently covered by late volcanic deposits) along the caldera marginal faults, and the main structural lineaments both bordering the resurgent block and cutting the caldera floor. These results allow us to both refine the current geological-structural framework and propose a new structural map that highlights the caldera boundary and its internal setting. This map is useful to interpret the phenomena occurring during unrest, and to improve both short-term and long-term volcanic hazards assessment.

  17. Retrieving the Stress Field Within the Campi Flegrei Caldera (Southern Italy) Through an Integrated Geodetical and Seismological Approach

    NASA Astrophysics Data System (ADS)

    D'Auria, Luca; Massa, Bruno; Cristiano, Elena; Del Gaudio, Carlo; Giudicepietro, Flora; Ricciardi, Giovanni; Ricco, Ciro

    2015-11-01

    We investigated the Campi Flegrei caldera using a quantitative approach to retrieve the spatial and temporal variations of the stress field. For this aim we applied a joint inversion of geodetic and seismological data to a dataset of 1,100 optical levelling measurements and 222 focal mechanisms, recorded during the bradyseismic crisis of 1982-1984. The inversion of the geodetic dataset alone, shows that the observed ground deformation is compatible with a source consisting of a planar crack, located at the centre of the caldera at a depth of about 2.56 km and a size of about 4 × 4 km. Inversion of focal mechanisms using both analytical and graphical approaches, has shown that the key features of the stress field in the area are: a nearly subvertical σ 1 and a sub-horizontal, roughly NNE-SSW trending σ 3. Unfortunately, the modelling of the stress fields based only upon the retrieved ground deformation source is not able to fully account for the stress pattern delineated by focal mechanism inversion. The introduction of an additional regional background field has been necessary. This field has been determined by minimizing the difference between observed slip vectors for each focal mechanism and the theoretical maximum shear stress deriving from both the volcanic (time-varying) and the regional (constant) field. The latter is responsible for a weak NNE-SSW extension, which is consistent with the field determined for the nearby Mt. Vesuvius volcano. The proposed approach accurately models observations and provides interesting hints to better understand the dynamics of the volcanic unrest and seismogenic processes at Campi Flegrei caldera. This procedure could be applied to other volcanoes experiencing active ground deformation and seismicity.

  18. The Campi Flegrei caldera (Italy): Formation and evolution in interplay with sea-level variations since the Campanian Ignimbrite eruption at 39 ka

    NASA Astrophysics Data System (ADS)

    Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

    2016-11-01

    To date, the origin of the Campi Flegrei caldera is still under debate and may be related to (1) a single caldera collapse associated with the Neapolitan Yellow Tuff (NYT) eruption, (2) two subsequent caldera collapses associated with the NYT and the preceding Campanian Ignimbrite (CI) eruptions forming a nested-caldera complex, or (3) not related to a caldera collapse after all. Here, we study the submerged portion of the caldera, which has favored a marine depositional setting and, thus, represents an ideal location for the reconstruction of its formation history, utilizing multichannel seismic data. Volcanic deposits and edifices were seismically distinguished from sedimentary successions, and the stratigraphy could be refined and extended back to the Campanian Ignimbrite eruption at 39 ka. High-resolution multichannel reflection seismic data revealed the existence of a nested-caldera complex formed during the CI eruption at 39 ka and the more recent NYT eruption at 15 ka. A ring-fault bounding an inner caldera collapse structure was clearly imaged. It appears that this inner ring-fault was initially activated during the CI caldera collapse and later reactivated during the NYT caldera collapse with different amounts of subsidence. The NYT caldera probably formed during an asymmetrical collapse with a maximum subsidence of 75 m in the offshore portion. The vertical displacement related to the CI caldera collapse may be significantly larger. The submerged caldera depression accommodates post-eruption sediments. Within this high-resolution archive, two major unconformities developed at 8.6 ka and 5 ka, when resurgence-related uplift exceeded the rate of sea-level rise concurrent with the emersion of the La Starza terrace. A previously unknown post-collapse submarine volcanic mound located between Nisida Island and Nisida Bank probably formed between 4.8 and 3.7 ka. Also, the Penta Palummo Bank appears to be constructed of at least two monogenetic volcanic edifices

  19. Audiomagnetotellurics-Magnetotelluric (AMT-MT) survey of the Campi Flegrei inner caldera

    NASA Astrophysics Data System (ADS)

    Siniscalchi, Agata; Tripaldi, Simona; Romano, Gerardo; D'Auria, Luca; Improta, Luigi; Petrillo, Zaccaria

    2017-04-01

    In the framework of the EU project MED-SUV, an audiomagnetotellurics-magnetotelluric (AMT-MT) survey in the frequency band 0.1-100kHz was performed in the eastern border of the Campi Flegrei inner caldera comprising the area where seismicity is concentred in the last decade. This survey was aimed to provide new insights on the electrical resistivity structure of the subsoil. Among all the collected MT soundings, twenty-two, on a total of forty-three, were selected along a WSW-ENE alignment that crosses the main fumarole emissions (Solfatara, Pisciarelli and Agnano) and used for 2D regularized inversion. The obtained model is characterized by a quite narrow resistivity range that well matches typical range of enhanced geothermal environment as largely documented in the international literature. In particular focusing on the Solfatara and Pisciarelli districts the resistivity distribution clearly calls to mind the behavior of a high temperature geothermal system with a very conductive cap in the shallower part. Here the presence of gaps in this conductor just in correspondence of the main superficial emissions describes the inflow and outflow pathway of the shallow fluids circulation. A high resistive reservoir appearing at a depth of about 500 m b.s.l.. WithinWithin this region we selected a vertical resistivity profile just in correspondence of a Vp/Vs profile versus depth coming from a passive seismic tomography (Vanorio et al., 2005). The comparison of the two behaviors shows a clear anti-correlation between the two physical parameters (high resistivity and low Vp/Vs) in the depth range 500-1000 m supporting the interpretation that an over-pressurized gas bearing rocks under supercritical conditions constituting the reservoir of the enhanced geothermal system. On the eastern side of this resistive plume up to 2.5 km of depth is present a local relative conductive unit underneath the Pisciarelli area. In the same volume most of the recent (from 2005 up to date

  20. 40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy): Toward a new chronostratigraphic reconstruction of the Holocene volcanic activity

    USGS Publications Warehouse

    Fedele, L.; Insinga, D.D.; Calvert, A.T.; Morra, V.; Perrotta, A.; Scarpati, C.

    2011-01-01

    The Campi Flegrei hosts numerous monogenetic vents inferred to be younger than the 15 ka Neapolitan Yellow Tuff. Sanidine crystals from the three young Campi Flegrei vents of Fondi di Baia, Bacoli and Nisida were dated using 40Ar/39Ar geochronology. These vents, together with several other young edifices, occur roughly along the inner border of the Campi Flegrei caldera, suggesting that the volcanic conduits are controlled by caldera-bounding faults. Plateau ages of ∼9.6 ka (Fondi di Baia), ∼8.6 ka (Bacoli) and ∼3.9 ka (Nisida) indicate eruptive activity during intervals previously interpreted as quiescent. A critical revision, involving calendar age correction of literature 14C data and available 40Ar/39Ar age data, is presented. A new reference chronostratigraphic framework for Holocene Phlegrean activity, which significantly differs from the previously adopted ones, is proposed. This has important implications for understanding the Campi Flegrei eruptive history and, ultimately, for the evaluation of related volcanic risk and hazard, for which the inferred history of its recent activity is generally taken into account.

  1. Study of the 2011-2013 unrest at Campi Flegrei caldera (Italy) through InSAR and 3D modelling

    NASA Astrophysics Data System (ADS)

    Trasatti, Elisa; Polcari, Marco; Bignami, Christian; Bonafede, Maurizio; Buongiorno, Fabrizia; Stramondo, Salvatore

    2014-05-01

    Campi Flegrei is a nested caldera in Italy, at the western edge of the Bay of Naples. Together with Vesuvius and Mt Etna, it is one of the Italian GeoHazard Supersites. The area is characterized by one of the highest volcanic hazard in the world, due to the very high density of inhabitants (1800/km2), the persistent activity of the system and the explosive character of volcanism. A major unrest episode took place in 1982-84, when the town of Pozzuoli, located at the caldera center, was uplifted by 1.80 m (~1 m/yr). Minor uplifts of few cm, seismic swarms and degassing episodes took place in 1989, 2000 and 2004-06. Since 2005 Campi Flegrei is uplifting, reaching a ground velocity of 9 cm/yr in 2012, showing that the caldera is in a critical state on the verge of instability. In the present work we consider InSAR time series of the recent activity (2010-2013) detected by COSMO SkyMed satellite. In particular, the time series show a progressive velocity increase of ground deformation during 2012, while it slowed down in 2013 approaching zero. The cumulative displacement from COSMO SkyMed descending orbit (March 2011 - March 2013) show a semicircular pattern centered in Pozzuoli with a maximum LoS (Line of Sight) displacement of 11 cm and maximum velocity 9 cm/yr reached along the coastline. The spatial distribution of the cumulative displacement from COSMO SkyMed ascending orbit show a similar behavior, confirming the bell-shaped pattern of the deformation at least inside the inner rim of the caldera. The cumulative ascending LoS displacement between March 2013 - September 2013 is 1-2 cm, confirming the stall of the unrest after the first few months of 2013 as observed by GPS. Initially, several source geometries are adopted (sphere, spheroid, sill) to model the cumulative deformation between 2011 and 2013. All the sources are located offshore Pozzuoli at a depth of about 2 km. The sphere and spheroid result to dilate at an annual volume variation rate of the order of

  2. ROCK PHYSICS. Rock physics of fibrous rocks akin to Roman concrete explains uplifts at Campi Flegrei Caldera.

    PubMed

    Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

    2015-08-07

    Uplifts in the Campi Flegrei caldera reach values unsurpassed anywhere in the world (~2 meters). Despite the marked deformation, the release of strain appears delayed. The rock physics analysis of well cores highlights the presence of two horizons, above and below the seismogenic area, underlying a coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix that results from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that characterizing the cementitious pastes in modern and Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture.

  3. Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 2. Pyroclastic density current invasion maps

    NASA Astrophysics Data System (ADS)

    Neri, Augusto; Bevilacqua, Andrea; Esposti Ongaro, Tomaso; Isaia, Roberto; Aspinall, Willy P.; Bisson, Marina; Flandoli, Franco; Baxter, Peter J.; Bertagnini, Antonella; Iannuzzi, Enrico; Orsucci, Simone; Pistolesi, Marco; Rosi, Mauro; Vitale, Stefano

    2015-04-01

    Campi Flegrei (CF) is an example of an active caldera containing densely populated settlements at very high risk of pyroclastic density currents (PDCs). We present here an innovative method for assessing background spatial PDC hazard in a caldera setting with probabilistic invasion maps conditional on the occurrence of an explosive event. The method encompasses the probabilistic assessment of potential vent opening positions, derived in the companion paper, combined with inferences about the spatial density distribution of PDC invasion areas from a simplified flow model, informed by reconstruction of deposits from eruptions in the last 15 ka. The flow model describes the PDC kinematics and accounts for main effects of topography on flow propagation. Structured expert elicitation is used to incorporate certain sources of epistemic uncertainty, and a Monte Carlo approach is adopted to produce a set of probabilistic hazard maps for the whole CF area. Our findings show that, in case of eruption, almost the entire caldera is exposed to invasion with a mean probability of at least 5%, with peaks greater than 50% in some central areas. Some areas outside the caldera are also exposed to this danger, with mean probabilities of invasion of the order of 5-10%. Our analysis suggests that these probability estimates have location-specific uncertainties which can be substantial. The results prove to be robust with respect to alternative elicitation models and allow the influence on hazard mapping of different sources of uncertainty, and of theoretical and numerical assumptions, to be quantified.

  4. Permeability and continuous gradient temperature monitoring of volcanic rocks: new insights from borehole and laboratory analysis at the Campi Flegrei caldera (Southern Italy).

    NASA Astrophysics Data System (ADS)

    Carlino, Stefano; Piochi, Monica; Tramelli, Anna; Troise, Claudia; Mormone, Angela; Montanaro, Cristian; Scheu, Bettina; Klaus, Mayer; Somma, Renato; De Natale, Giuseppe

    2016-04-01

    The pilot borehole recently drilled in the eastern caldera of Campi Flegrei (Southern Italy), during the Campi Flegrei Deep Drill Project (CFDDP) (in the framework of the International Continental Scientific Drilling Program) allowed (i) estimating on-field permeability and coring the crustal rocks for laboratory experiments, and (ii) determining thermal gradient measurements down to ca. 500 m of depth. We report here a first comparative in situ and laboratory tests to evaluate the rock permeability in the very high volcanic risk caldera of Campi Flegrei, in which ground deformations likely occur as the persistent disturbance effect of fluid circulation in the shallower geothermal system. A large amount of petro-physical information derives from outcropping welded tuffs, cores and geophysical logs from previous AGIP's drillings, which are located in the central and western part of the caldera. We discuss the expected scale dependency of rock permeability results in relation with well-stratigraphy and core lithology, texture and mineralogy. The new acquired data improve the database related to physical property of Campi Flegrei rocks, allowing a better constrain for the various fluid-dynamical models performed in the tentative to understand (and forecast) the caldera behavior. We also present the first data on thermal gradient continuously measured through 0 - to 475 m of depth by a fiber optic sensor installed in the CFDDP pilot hole. As regards, we show that the obtained values of permeability, compared with those inferred from eastern sector of the caldera, can explain the different distribution of temperature at depth, as well as the variable amount of vapor phase in the shallow geothermal system. The measured temperatures are consistent with the distribution of volcanism in the last 15 ka.

  5. Crystallization and eruption ages of Breccia Museo (Campi Flegrei caldera, Italy) plutonic clasts and their relation to the Campanian ignimbrite

    NASA Astrophysics Data System (ADS)

    Gebauer, Samantha K.; Schmitt, Axel K.; Pappalardo, Lucia; Stockli, Daniel F.; Lovera, Oscar M.

    2014-01-01

    The Campi Flegrei volcanic district (Naples region, Italy) is a 12-km-wide, restless caldera system that has erupted at least six voluminous ignimbrites during the late Pleistocene, including the >300 km3 Campanian ignimbrite (CI) which originated from the largest known volcanic event of the Mediterranean region. The Breccia Museo (BM), a petrologically heterogeneous and stratigraphically complex volcanic deposit extending over 200 km2 in close proximity to Campi Flegrei, has long remained contentious regarding its age and stratigraphic relation to the CI. Here, we present crystallization and eruption ages for BM plutonic ejecta clasts that were determined via uranium decay series and (U-Th)/He dating of zircon, respectively. Despite mineralogical and textural heterogeneity of these syenitic clasts, their U-Th zircon rim crystallization ages are indistinguishable with an average age of 49.7 ± 2.5 ka (2σ errors; mean square of weighted deviates MSWD = 1.2; n = 34). A subset of these crystals was used to obtain disequilibrium-corrected (U-Th)/He zircon ages which average 41.7 ± 1.8 ka (probability of fit P = 0.54; n = 15). This age closely overlaps with published CI 40Ar/39Ar eruption ages (40.6 ± 0.1 ka) after recalibration to recently revised flux monitor ages. Concordant eruption ages for BM and CI agree with previous chemostratigraphic and paleomagnetic correlations, suggesting their origin from the same eruption. However, they are at variance with recalibrated 40Ar/39Ar ages which have BM postdate CI by 3 ± 1 ka. BM syenites show similar geochemical and Sr-Nd isotopical features of pre-caldera rocks erupted between 58 and 46 ka, but are distinctive from subsequent caldera-forming magmas. Energy-constrained assimilation and fractional crystallization modeling of Nd-Sr isotopic data suggests that pre-caldera magmas formed a carapace of BM-type intrusions in a mid-crust magma chamber (≥8 km depth) shielding the younger CI magma from contamination by

  6. A model for seismicity rates observed during the 1982-1984 unrest at Campi Flegrei Caldera (Italy).

    NASA Astrophysics Data System (ADS)

    Elina Belardinelli, Maria; Bizzarri, Andrea; Ricciardi, Giovanni P.; Berrino, Giovanna

    2010-05-01

    In order to model seismicity during the 1982-1984 unrest at Campi Flegrei caldera (Italy), we compute static stress changes caused by an inflating source in a layered half-space. Stress changes are evaluated on optimally oriented planes for shear failure, assuming a regional deviatoric stress with horizontal extensional axis trending NE-SW. The inflating source is modelled as inferred by previous studies based on the inversion of geodetic data and having the same crustal model here assumed. We found that the area affected by the largest Coulomb stress changes is elliptical and that inverse slip over the source can be discouraged by the assumed regional stress. These results are in agreement with observations concerning seismicity developed during the 1982-1984 unrest at Campi Flegrei. We assume that the temporal evolution of uplift observed by a tide-gauge at Pozzuoli, normalized to the maximum value, was due mainly to time dependent processes occurring at the inflating source. We attribute the same normalized time-dependence to each component of stress change (shear and normal stress changes) averaged in the region interested by the observed seismicity. We then model seismicity rate changes associated to these time-dependent stress changes, by following the approach indicated by Dieterich (1994) on the basis of the rate- and state-dependent rheology of faults. The seismicity rate as a function of time resulting from the present model is in general agreement with observations for the period 1982-1984. According to observations, several peaks of deformation rate history are closely followed by peaks in seismicity rate. In order to model this effect, a prompt response of the fault system is required, allowing to constrain the direct effect on friction (aσ) on the same faults.

  7. Hydrothermal activity at Campi Flegrei caldera: rock mechanical properties and implications for outgassing and possible phreatic eruptions

    NASA Astrophysics Data System (ADS)

    Mayer, K.; Montanaro, C.; Scheu, B.; Isaia, R.; Mangiacapra, A.; Gresse, M.; Vandemeulebrouck, J.; Moretti, R.; Dingwell, D. B.

    2015-12-01

    The Solfatara and Pisciarelli fumaroles are the main surface manifestations of the vigorous hydrothermal activity within the Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing and leads to a strong alteration of the volcanic products in both areas. Consistent with the volcanic history of the area, Solfatara and Pisciarelli are posited as having the highest probability for the opening of new vents, and in particular for possible phreatic activity within the Campi Flegrei system. Hydrothermal alteration deeply affects all the rocks exposed within Solfatara sector, including lava domes, breccias, as well as pyroclastic fallout ash beds and pyroclastic density current deposits. This results in changes of the volcanic rock's original microstructure and of their physical and mechanical properties, which in turn control both the outgassing and their fragmentation behaviors. Here, samples from the wall rocks in the vicinity of the Solfatara and Pisciarelli fumaroles have been subjected to geochemical, physical and mechanical properties characterization. In addition, surficial Solfatara crater floor deposits were characterized and their properties, in particular permeability, were mapped. Results show that hydrothermal alteration increases porosity and permeability of the crater wall samples favoring outgassing, while decreasing the rock strength. At the crater floor the outgassing occurs mainly along the crack system, which has also generated crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and sulfur-hardened levels, whereas their surfacing is hindered by compacted fine-grained, low permeability layers. Decompression experiments were performed to simulate a phreatic eruption at shallow depth. We used crater-wall samples representing the rocks in the proximity of high degassing areas. Changes in the fragmentation behavior and ejection dynamics, depending on the

  8. The Evolution of the Campi Flegrei caldera (Italy): High- and low-frequency multichannel 2.5D seismic surveying for an amphibian IODP/ICDP drilling approach

    NASA Astrophysics Data System (ADS)

    Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

    2016-04-01

    Caldera-forming eruptions are considered as one of the most catastrophic natural events to affect the Earth's surface and human society. The half-submerged Campi Flegrei caldera, located in southern Italy, belongs to the world's most active calderas and, thus, has received particular attention in scientific communities and governmental institutions. Therefore, it has also become subject to a joint approach in the IODP and ICDP programmes. Despite ample research, no scientific consensus regarding the formation history of the Campi Flegrei caldera has been reached yet. So far, it is still under debate whether the Campi Flegrei caldera was formed by only one ignimbritic eruption, namely the Neapolitan Yellow Tuff (NYT) eruption at 15 ka or, if it is a nested-caldera system related to the NYT and the Campanian Ignimbrite (CI) eruption at 39 ka. In the last decades, the Campi Flegrei caldera has been characterized by short-term episodes of unrest involving considerable ground deformation (uplift and subsidence of several meters), seismicity and increased temperature at fumaroles. Furthermore, long-term deformation can be observed in the central part of the caldera with uplift rates of several tens of meters within a few thousand years. Recently, it has been proposed that the long-term deformation may be related to caldera resurgence, while short-term uplift episodes are probably triggered by the injection of magmatic fluids into a shallow hydrothermal system at ~2 km depth. However, both long-term and short term uplift could be interpreted as eruption precursor, thereby posing high-concern for a future eruption, which would expose more than 1.5 million people living in the surroundings of the volcanic district to extreme volcanic risks. During a joint Italian-German research expedition in 2008, a semi-3D grid (100-150 m profile spacing) of high-frequency (up to 1000 Hz) multichannel seismic data were acquired to support both the ongoing onshore ICDP and a proposed

  9. Earthquakes location and stress field inversion for the 1984 seismic crisis at Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Satriano, C.; Capuano, P.; de Matteis, R.; Pasquale, G.; Zollo, A.

    2009-04-01

    he Campi Flegrei (CF) alkali-trakitic caldera is an active volcanic system located 15 km west of the city of Naples, southern Italy, covering an area of about 400 km2. It is located within a NE-SW trending large graben (Campanian Plain) formed, at eastern margin of the Tyrrhenian sea, in the Plio-Pleistocene that is bordered by mostly Mesozoic carbonaceous rocks. CF is the northernmost of a group of Pleistocene volcanoes three of which (Ischia, CF and Vesuvius) have erupted in historical times. CF caldera is characterized by the presence of sparse volcanic craters as the results of several explosive eruptions. Like other calderas, CF periodically experiences significant unrest episodes which involve ground deformations and seismic swarms. Recently, two marked ground uplift took place in the area in 1970-1972 and 1982-1984. The latter, began in the second half of 1982 and was characterized by a total vertical displacement of 1.8 m accompanied by a seismic swarm of more that 10,000 shallow microearthquakes with a maximum duration magnitude of 4.2. A database, recently reconstructed, containing thousands of seismic waveforms collected by a digital network during the last 1984 strong crisis at Campi Flegrei caldera has been used to perform new earthquake locations, focal mechanisms determination and the estimation of the local stress field using a novel 3D P-wave velocity model of the caldera. The 3D P-wave velocity model has been constructed using the results of a recent active/passive seismic tomography inversion and it incorporates the main 3D features of the area, including the buried rim of the caldera, and shows velocity ranging from 1 km/s ca. at the surface to 7 km/s ca. at a greater depth. About 700 earthquakes have been relocated using a probabilistic global search method, determining the best Vp/Vs ratio. The earthquakes are mostly clustered in the caldera centre near the Solfatara crater with hypocenter depth of about 1-4 km inside the volcano

  10. Hydrothermal fluid flow models of Campi Flegrei caldera, Italy constrained by InSAR surface deformation time series observations

    NASA Astrophysics Data System (ADS)

    Lundgren, P.; Lanari, R.; Manzo, M.; Sansosti, E.; Tizzani, P.; Hutnak, M.; Hurwitz, S.

    2008-12-01

    Campi Flegrei caldera, Italy, located along the Bay of Naples, has a long history of significant vertical deformation, with the most recent large uplift (>1.5m) occurring in 1983-1984. Each episode of uplift has been followed by a period of subsidence that decreases in rate with time and may be punctuated by brief episodes of lesser uplift. The large amplitude of the major uplifts that occur without volcanic activity, and the subsequent subsidence has been argued as evidence for hydrothermal amplification of any magmatic source. The later subsidence and its temporal decay have been argued as due to diffusion of the pressurized caldera fill material into the less porous surrounding country rock. We present satellite synthetic aperture radar (SAR) interferometry (InSAR) time series analysis of ERS and Envisat data from the European Space Agency, based on exploiting the Small Baseline Subset (SBAS) approach [Berardino et al., 2002]; this allows us to generate maps of relative surface deformation though time, beginning in 1992 through 2007, that are relevant to both ascending and descending satellite orbits. The general temporal behavior is one of subsidence punctuated by several lesser uplift episodes. The spatial pattern of deformation can be modeled through simple inflation/deflation sources in an elastic halfspace. Given the evidence to suggest that fluids may play a significant role in the temporal deformation of Campi Flegrei, rather than a purely magmatic or magma chamber-based interpretation, we model the temporal and spatial evolution of surface deformation as a hydrothermal fluid flow process. We use the TOUGH2-BIOT2 set of numerical codes [Preuss et al., 1999; Hsieh, 1996], which couple multi-phase (liquid-gas) and multi-component (H2O-CO2) fluid flow in a porous or fractured media with plane strain deformation and fluid flow in a linearly elastic porous medium. We explore parameters related to the depth and temporal history of fluid injection, fluid

  11. Timescales of magma processes occurred prior to recent Campi Flegrei caldera eruptions: first results from diffusion profiles on plagioclase phenocrysts

    NASA Astrophysics Data System (ADS)

    D'Antonio, Massimo; Arienzo, Ilenia; Fedele, Lorenzo; Iovine, Raffaella; Carmine Mazzeo, Fabio; Civetta, Lucia; Orsi, Giovanni; Wörner, Gerhard

    2015-04-01

    Knowledge of the timescales of magma rising and stagnation, as well as mingling/mixing processes occurring in the shallow plumbing system of an active volcano is crucial for volcanic hazard assessment and risk mitigation. Among few recently developed methodologies, high-precision, high spatial resolution analysis of major-, minor- and trace elements on zoned phenocrysts through electron microprobe techniques represents a powerful tool to provide good estimates of timescales of pre-eruptive magma rising, stagnation and/or mingling/mixing processes. To this purpose, volcanic rock samples of trachytic composition representative of the Agnano-Monte Spina eruption (4.7 ka CAL BP) occurred at the Campi Flegrei caldera (southern Italy) have been selected. The investigation has been carried out in the framework of Project V2 - Precursori di Eruzioni, funded by the Italian Dipartimento per la Protezione Civile - Istituto Nazionale di Geofisica e Vulcanologia. The investigated rock samples are pumice fragments from which double-polished, 100 µm thick thin sections have been prepared for analytical purposes. Back-scattered electrons (BSE) images have been acquired at the scanning electron microscope (SEM), in order to identify the plagioclase phenocrysts suitable to be analyzed successively, selected among those that best display their zoning. After a careful observation of the BSE images, major-, minor- and selected trace element contents have been determined through combined energy-dispersive and wavelength-dispersive system electron microprobe analyses (EDS-WDS-EMPA) on transects crossing the growth zones of the selected phenocrysts. This methodology has allowed reconstructing the diffusion profile of some key-elements through the growth zones of the investigated phenocrysts. Successively, the diffusion profiles have been combined with textural features obtained through BSE images in order to obtain diffusion models aimed at estimating the timescales of crystals

  12. Pyroclastic density current hazard maps at Campi Flegrei caldera (Italy): the effects of event scale, vent location and time forecasts.

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Andrea; Neri, Augusto; Esposti Ongaro, Tomaso; Isaia, Roberto; Flandoli, Franco; Bisson, Marina

    2016-04-01

    Today hundreds of thousands people live inside the Campi Flegrei caldera (Italy) and in the adjacent part of the city of Naples making a future eruption of such volcano an event with huge consequences. Very high risks are associated with the occurrence of pyroclastic density currents (PDCs). Mapping of background or long-term PDC hazard in the area is a great challenge due to the unknown eruption time, scale and vent location of the next event as well as the complex dynamics of the flow over the caldera topography. This is additionally complicated by the remarkable epistemic uncertainty on the eruptive record, affecting the time of past events, the location of vents as well as the PDCs areal extent estimates. First probability maps of PDC invasion were produced combining a vent-opening probability map, statistical estimates concerning the eruptive scales and a Cox-type temporal model including self-excitement effects, based on the eruptive record of the last 15 kyr. Maps were produced by using a Monte Carlo approach and adopting a simplified inundation model based on the "box model" integral approximation tested with 2D transient numerical simulations of flow dynamics. In this presentation we illustrate the independent effects of eruption scale, vent location and time of forecast of the next event. Specific focus was given to the remarkable differences between the eastern and western sectors of the caldera and their effects on the hazard maps. The analysis allowed to identify areas with elevated probabilities of flow invasion as a function of the diverse assumptions made. With the quantification of some sources of uncertainty in relation to the system, we were also able to provide mean and percentile maps of PDC hazard levels.

  13. Repeated fluid-transfer episodes as a mechanism for the recent dynamics of Campi Flegrei caldera (1989-2010)

    NASA Astrophysics Data System (ADS)

    D'Auria, L.; Giudicepietro, F.; Aquino, I.; Borriello, G.; Del Gaudio, C.; Lo Bascio, D.; Martini, M.; Ricciardi, G. P.; Ricciolino, P.; Ricco, C.

    2011-04-01

    We have analyzed a multiparametric data set of seismological, geodetic and geochemical data recorded at Campi Flegrei caldera since 1982. We focus here on the period 1989-2010 that followed the last bradyseismic crisis of 1982-1984. Since then, there have been at least five repeated minor episodes of ground uplift accompanied by seismicity. We have reanalyzed old paper and digital seismic data sets dating back to 1982. The paper recordings show evidence of long-period events in January 1982 and March 1989, and we have digitized some of these significant waveforms. Furthermore, the revision of digital seismograms dating back to 1994 shows a significant swarm of long-period events in August 1994. Volcano-tectonic and long-period events hypocenters have been relocated in a three-dimensional velocity model. Statistical analysis of volcano-tectonic seismicity shows many similarities and few differences between 1982-1984 and the following period 1989-2010. Long-period waveforms have been analyzed using spectral analysis, which shows a grouping into three macrofamilies. Similarities in the seismic signature of episodes of minor uplift suggest that they originate from the injection of fluids into the deep part of a geothermal reservoir (about 2.5 km depth) and in its transfer toward a shallower part (about 0.75 km depth). Most of the observed geophysical signals are related to this second phase. The evidence consists of spatial and temporal connections between the ground deformation, long-period and volcano-tectonic seismicity and changes in the geochemical parameters of fumaroles. In this study we focused our analysis on two uplift episodes observed in 2000 and 2006. The joint inversion of Differential Synthetic Aperture Radar (DInSAR) and tiltmeter data show that during these periods the ground deformation was generated by at least two distinct sources located at different depths, with the shallower activated in the later stages of the uplift episodes. Our interpretation

  14. Seismicity associated with the 2004 2006 renewed ground uplift at Campi Flegrei Caldera, Italy

    NASA Astrophysics Data System (ADS)

    Saccorotti, G.; Petrosino, S.; Bianco, F.; Castellano, M.; Galluzzo, D.; La Rocca, M.; Del Pezzo, E.; Zaccarelli, L.; Cusano, P.

    2007-11-01

    Following the significant ground uplift (˜1.8 m) of the 1982-1984 bradyseismic crisis, the recent history of Campi Flegrei volcanic complex (Italy) has been dominated by a subsidence phase. Recent geodetic data demonstrate that the subsidence has terminated, and that positive ground deformation renewed in November 2004, at a low but accelerating rate leading to about 4 cm of uplift by the end of October 2006. As in previous episodes, ground uplift has been accompanied by swarms of micro-earthquakes ( M ≤ 1.4) in three distinct episodes: October 2005, October 2006 and December 2006. Hypocenters of these earthquakes are mainly located beneath the Solfatara Volcano at depths ranging between 0.5 and 4 km. Inversion of S-wave spectra indicates source radius and stress drop on the order of 30-60 m and 10 4-9 × 10 5 Pa, respectively. Fault plane solutions indicate predominantly normal mechanisms. Accompanying the October 2006 swarm, we detected intense long-period (LP) activity for about 1 week. These signals consist of weak, monochromatic oscillations whose spectra exhibit a main peak at frequency ˜0.8 Hz. This peak is common to all the stations of the network, and not present in the noise spectra, suggesting that it is a source effect. About 75% of the detected LPs cluster into three groups of mutually similar events. Adjustment of waveforms using cross-correlation allows for precise alignment and stacking, which enhances signal onsets and permits accurate absolute arrival picks, and thus better absolute as well as relative locations. Locations associated with the three different clusters are very similar, and appear to delineate the SE rim of the Solfatara Volcano at a depth of about 500 m. The most likely source process for the LP events involves the resonance of a fluid-filled, buried cavity. Quality factors of the resonator cluster in a narrow interval around 4, which is consistent with the vibration of a buried cavity filled with a water-vapour mixture at poor

  15. A geochemical and geophysical reappraisal to the significance of the recent unrest at Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Moretti, Roberto; De Natale, Giuseppe; Troise, Claudia

    2017-04-01

    Volcanic unrest at calderas involve complex interaction between magma, hydrothermal fluids and crustal stress and strain. Campi Flegrei caldera (CFc), located in the Naples (Italy) area and characterised by the highest volcanic risk on Earth for the extreme urbanisation, undergoes unrest phenomena involving several meters of uplift and intense shallow micro-seismicity since several decades. Despite unrest episodes display in the last decade only moderate ground deformation and seismicity, current interpretations of geochemical data point to a highly pressurized hydrothermal system. We show that at CFc, the usual assumption of vapour-liquid coexistence in the fumarole plumes leads to largely overestimated hydrothermal pressures and, accordingly, interpretations of elevated unrest. By relaxing unconstrained geochemical assumptions, we infer an alternative model yielding better agreement between geophysical and geochemical observations. The model reconciles discrepancies between what observed 1) for two decades since the 1982-84 large unrest, when shallow magma was supplying heat and fluids to the hydrothermal system, and 2) in the last decade. Compared to the 1980's unrest, the post-2005 phenomena are characterized by much lower aquifers overpressure and magmatic involvement, as indicated by geophysical data and despite large changes in geochemical indicators. Our interpretation points out a model in which shallow sills, intruded during 1969-1984, have completely cooled, so that fumarole emissions are affected now by deeper, CO2-richer, magmatic gases producing a relatively modest heating and overpressure of the hydrothermal system. Our results do have important implications on the short-term eruption hazard assessment and on the best strategies for monitoring and interpreting geochemical data.

  16. Sustainability assessment of geothermal exploitation by numerical modelling: the example of high temperature Mofete geothermal field at Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Carlino, Stefano; Troiano, Antonio; Giulia Di Giuseppe, Maria; Tramelli, Anna; Troise, Claudia; Somma, Renato; De Natale, Giuseppe

    2015-04-01

    The active volcanic area of Campi Flegrei caldera has been the site of many geothermal investigations, since the early XX century. This caldera is characterised by high heat flow, with maximum value > 150 mWm-2, geothermal gradients larger than 200°Ckm-1 and diffuse magmatic gases discharge at the surface. These features encouraged an extensive campaign for geothermal investigation, started in 1939, with many drillings performed at Campanian volcanoes (Campi Flegrei and Ischia) and later at Vesuvius. Several wells aimed to the exploitation of high enthalpy geothermal energy, were drilled in the Campi Flegrei caldera, down to a maximum depth of ~3 km involving mainly two sites (Mofete and S.Vito geothermal fields) located in western and northern sector of caldera respectively. The most interesting site for geothermal exploitation was the Mofete zone, where a number of 4 productive wells were drilled and tested to produce electrical power. Based on data inferred from the productive tests it was established a potential electrical extractable power from Mofete field of at least 10MWe. More recently an empirical evaluation of the whole geothermal potential of the caldera provides a value of more than 1 GWe. The results of AGIP-ENEL exploration at Campi Flegrei highlighted the feasibility of geothermal exploitation. Here, we show for the first time the results of numerical simulations (TOUGH2 code ®) of fluids extraction and reinjection from the Mofete geothermal field, in order to produce at least 5MWe from zero emission power plant (Organic Rankine Cycle type). The simulation is aimed to understand the perturbation of the geothermal reservoir in terms of temperature, pressure change, and possible related seismicity, after different simulated time of exploitation. The modeling is mainly constrained by the data derived from geothermal exploration and productive tests performed since 1979 by AGIP-ENEL Companies. A general assessment of the maximum potential magnitude

  17. The Campi Flegrei Deep Drilling Project (CFDDP): New insight on caldera structure, evolution and hazard implications for the Naples area (Southern Italy)

    NASA Astrophysics Data System (ADS)

    De Natale, Giuseppe; Troise, Claudia; Mark, Darren; Mormone, Angela; Piochi, Monica; Di Vito, Mauro; Isaia, Roberto; Carlino, Stefano; Barra, Diana; Somma, Renato

    2017-04-01

    The 501 m deep hole of the Campi Flegrei Deep Drilling Project, located west of the Naples metropolitan area and inside the Campi Flegrei caldera, gives new insight to reconstruct the volcanotectonic evolution of this highly populated volcano. It is one of the highest risk volcanic areas in the world, but its tectonic structure, eruptive history, and size of the largest eruptions are intensely debated in the literature. New stratigraphic and 40Ar/39Ar geochronological dating allow us to determine, for the first time, the age of intracaldera deposits belonging to the two highest magnitude caldera-forming eruptions (i.e., Campanian Ignimbrite, CI, 39 ka, and Neapolitan Yellow Tuff, NYT, 14.9 ka) and to estimate the amount of collapse. Tuffs from 439 m of depth yield the first 40Ar/39Ar age of ca. 39 ka within the caldera, consistent with the CI. Volcanic rocks from the NYT were, moreover, detected between 250 and 160 m. Our findings highlight: (i) a reduction of the area affected by caldera collapse, which appears to not include the city of Naples; (ii) a small volume of the infilling caldera deposits, particularly for the CI, and (iii) the need for reassessment of the collapse amounts and mechanisms related to larger eruptions. Our results also imply a revaluation of volcanic risk for the eastern caldera area, including the city of Naples. The results of this study point out that large calderas are characterized by complex collapse mechanisms and dynamics, whose understanding needs more robust constraints, which can be obtained from scientific drilling.

  18. The Campi Flegrei Deep Drilling Project (CFDDP): New insight on caldera structure, evolution and hazard implications for the Naples area (Southern Italy)

    NASA Astrophysics Data System (ADS)

    De Natale, Giuseppe; Troise, Claudia; Mark, Darren; Mormone, Angela; Piochi, Monica; Di Vito, Mauro A.; Isaia, Roberto; Carlino, Stefano; Barra, Diana; Somma, Renato

    2016-12-01

    The 501 m deep hole of the Campi Flegrei Deep Drilling Project, located west of the Naples metropolitan area and inside the Campi Flegrei caldera, gives new insight to reconstruct the volcano-tectonic evolution of this highly populated volcano. It is one of the highest risk volcanic areas in the world, but its tectonic structure, eruptive history, and size of the largest eruptions are intensely debated in the literature. New stratigraphic and 40Ar/39Ar geochronological dating allow us to determine, for the first time, the age of intracaldera deposits belonging to the two highest magnitude caldera-forming eruptions (i.e., Campanian Ignimbrite, CI, 39 ka, and Neapolitan Yellow Tuff, NYT, 14.9 ka) and to estimate the amount of collapse. Tuffs from 439 m of depth yield the first 40Ar/39Ar age of ca. 39 ka within the caldera, consistent with the CI. Volcanic rocks from the NYT were, moreover, detected between 250 and 160 m. Our findings highlight: (i) a reduction of the area affected by caldera collapse, which appears to not include the city of Naples; (ii) a small volume of the infilling caldera deposits, particularly for the CI, and (iii) the need for reassessment of the collapse amounts and mechanisms related to larger eruptions. Our results also imply a revaluation of volcanic risk for the eastern caldera area, including the city of Naples. The results of this study point out that large calderas are characterized by complex collapse mechanisms and dynamics, whose understanding needs more robust constraints, which can be obtained from scientific drilling.

  19. A reappraisal of seismic Q evaluated in Campi Flegrei caldera. Receipt for the application to risk analysis

    NASA Astrophysics Data System (ADS)

    Del Pezzo, Edoardo; Bianco, Francesca

    2013-04-01

    The civil defense of Italy and the European community have planned to reformulate the volcanic risk in several volcanic areas of Italy, among which Mt. Vesuvius and Campi Flegrei, by taking into account the possible occurrence of damaging pre- or syn-eruptive seismic events. Necessary to achieve this goal is the detailed knowledge of the local attenuation-distance relations. In the present note, we make a survey of the estimates of seismic quality factor (the inverse is proportional to the attenuation coefficient with distance) reported in literature for the area of Campi Flegrei where many, but sometimes contradictory results have been published on this topic. We try to review these results in order to give indications for their correct use when calculating the attenuation laws for this area.

  20. A geochemical and geophysical reappraisal to the significance of the recent unrest at Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Moretti, Roberto; De Natale, Giuseppe; Troise, Claudia

    2017-03-01

    Volcanic unrest at calderas involves complex interaction between magma, hydrothermal fluids, and crustal stress and strain. Campi Flegrei caldera (CFc), located in the Naples (Italy) area and characterized by the highest volcanic risk on Earth for the extreme urbanization, undergoes unrest phenomena involving several meters of uplift and intense shallow microseismicity since several decades. Despite unrest episodes display in the last decade only moderate ground deformation and seismicity, current interpretations of geochemical data point to a highly pressurized hydrothermal system. We show that at CFc, the usual assumption of vapor-liquid coexistence in the fumarole plumes leads to largely overestimated hydrothermal pressures and, accordingly, interpretations of elevated unrest. By relaxing unconstrained geochemical assumptions, we infer an alternative model yielding better agreement between geophysical and geochemical observations. The model reconciles discrepancies between what observed (1) for two decades since the 1982-1984 large unrest, when shallow magma was supplying heat and fluids to the hydrothermal system, and (2) in the last decade. Compared to the 1980's unrest, the post-2005 phenomena are characterized by much lower aquifers overpressure and magmatic involvement, as indicated by geophysical data and despite large changes in geochemical indicators. Our interpretation points out a model in which shallow sills, intruded during 1969-1984, have completely cooled, so that fumarole emissions are affected now by deeper, CO2-richer, magmatic gases producing the modest heating and overpressure of the hydrothermal system. Our results have important implications on the short-term eruption hazard assessment and on the best strategies for monitoring and interpreting geochemical data.Plain Language Summary<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is one of the most dangerous volcanoes on Earth. Last eruption occurred in 1538 but since decades it</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17.4153D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17.4153D"><span>Hydrothermal fluid venting in the offshore sector of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>: A geochemical, geophysical, and volcanological study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Napoli, R.; Aiuppa, A.; Sulli, A.; Caliro, S.; Chiodini, G.; Acocella, V.; Ciraolo, G.; Di Vito, M. A.; Interbartolo, F.; Nasello, C.; Valenza, M.</p> <p>2016-10-01</p> <p>The ongoing unrest at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc) in southern Italy is prompting exploration of its poorly studied offshore sector. We report on a multidisciplinary investigation of the Secca delle Fumose (SdF), a submarine relief known since antiquity as the largest degassing structure of the offshore sector of CFc. We combined high-resolution morphobathymetric and seismostratigraphic data with onshore geological information to propose that the present-day SdF morphology and structure developed during the initial stages of the last CFc eruption at Monte Nuovo in AD 1538. We suggest that the SdF relief stands on the eastern uplifted border of a N-S-trending graben-like structure formed during the shallow emplacement of the Monte Nuovo feeding dike. We also infer that the high-angle bordering faults that generated the SdF relief now preferentially allow the ascent of hot brines (with an equilibrium temperature of 179°C), thereby sustaining hydrothermal degassing on the seafloor. Systematic vertical seawater profiling shows that hydrothermal seafloor venting generates a sizeable CO2, pH, and temperature anomaly in the overlying seawater column. Data for the seawater vertical profile can be used to estimate the CO2 and energy (heat) outputs from the SdF area at ˜50 tons/d (˜0.53 kg/s) and ˜80 MW, respectively. In view of the cause-effect relationship with the Monte Nuovo eruption, and the substantial gas and energy outputs, we consider that the SdF hydrothermal system needs to be included in monitoring programs of the ongoing CFc unrest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.302..287B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.302..287B"><span>A model for seismicity rates observed during the 1982-1984 unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belardinelli, M. E.; Bizzarri, A.; Berrino, G.; Ricciardi, G. P.</p> <p>2011-02-01</p> <p>We consider the space-time distribution of seismicity during the 1982-1984 unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy) where a correlation between seismicity and rate of ground uplift was suggested. In order to investigate this effect, we present a model based on stress transfer from the deformation source responsible for the unrest to potential faults. We compute static stress changes caused by an inflating source in a layered half-space. Stress changes are evaluated on optimally oriented planes for shear failure, assuming a regional stress with horizontal extensional axis trending NNE-SSW. The inflating source is modeled as inferred by previous studies from inversion of geodetic data with the same crustal model here assumed. The magnitude of the regional stress is constrained by imposing an initial condition of "close to failure" to potential faults. The resulting spatial distribution of stress changes is in agreement with observations. We assume that the temporal evolution of ground displacement, observed by a tide-gauge at Pozzuoli, was due mainly to time dependent processes occurring at the inflating source. We approximate this time dependence in piecewise-linear way and we attribute it to each component of average stress-change in the region interested by the observed seismicity. Then we evaluate the effect of a time dependent stressing rate on seismicity, by following the approach indicated by Dieterich (1994) on the basis of the rate- and state-dependent rheology of faults. The seismicity rate history resulting from our model is in general agreement with data during the period 1982-1984 for reasonable values of unconstrained model-parameters, the initial value of the direct effect of friction and the reference shear stressing rate. In particular, this application shows that a decreasing stressing-rate is effective in damping the seismicity rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1614198M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1614198M"><span>Mineralogical and petrological investigations of rocks cored from depths higher than 440m during the CFDDP drilling activities at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (southern Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mormone, Angela; Piochi, Monica; Balassone, Giuseppina; Carlino, Stefano; Somma, Renato; Troise, Claudia; De Natale, Giuseppe</p> <p>2014-05-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is one of the highest-risk volcanic areas on the Earth and the drilling exploiting activities carried by the Azienda Geologica Italiana Petroli (AGIP) and the Società Anonima Forze Endogene Napoletane (SAFEN) since the '40 have produced the main constrains to the definition of the subsurface structure of the <span class="hlt">caldera</span>. The eastern part of the <span class="hlt">caldera</span> represents among the least known in the area in terms of both volcanic and geothermal evolution. Recently, in the 2012, the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Deep Drilling Project (CFDDP) allowed performing a 506m hole in this sector of the <span class="hlt">caldera</span>, i.e. in the Bagnoli Plain, where the western districts of the Neapolitan city developed. Here, we present the preliminary results from mineralogical, geochemical and petrological investigations of drilling core samples collected at -443 m and -506 m of depths. Scanning electron microscopy (SEM), microanalysis by energy dispersive spectroscopy (EDS) together with investigations by back-scattered electron mode (SEM-BSE), and powder X-Ray diffraction (XRD) allowed: 1) defining the primary sample lithology; 2) examining the features of both primary and secondary minerals; 3) describing the relationships among texture and secondary mineralization. Sr isotope analyses were furthermore performed on separated feldspars. Density measurements were also carried out on the bottom core. The investigated samples are representative of strongly altered, massive pyroclastic tuffs, which made of a chaotic ashy to sandy matrix including low crystalline juvenile scoria and pumice fragments. Textural features of secondary mineralization are consistent with circulation of hydrothermal fluids as the results of a wide geothermal resource in the <span class="hlt">caldera</span>. Comparing the paleo-temperature inferred by authigenic minerals occurrence and the temperature measured at the bottom hole (~60°C) during geophysical logs, we suggest the cooling of the hydrothermal system in the eastern sector of the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011BVol...73..295D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011BVol...73..295D"><span>The Averno 2 fissure eruption: a recent small-size explosive event at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>di Vito, Mauro Antonio; Arienzo, Ilenia; Braia, Giuseppe; Civetta, Lucia; D'Antonio, Massimo; di Renzo, Valeria; Orsi, Giovanni</p> <p>2011-04-01</p> <p>The Averno 2 eruption (3,700 ± 50 a B.P.) was an explosive low-magnitude event characterized by magmatic and phreatomagmatic explosions, generating mainly fall and surge beds, respectively. It occurred in the Western sector of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Campanian Region, South Italy) at the intersection of two active fault systems, oriented NE and NW. The morphologically complex crater area, largely filled by the Averno lake, resulted from vent activation and migration along the NE-trending fault system. The eruption generated a complex sequence of pyroclastic deposits, including pumice fall deposits in the lower portion, and prevailing surge beds in the intermediate-upper portion. The pyroclastic sequence has been studied through stratigraphical, morphostructural and petrological investigations, and subdivided into three members named A through C. Member A was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km. During this phase the eruption reached its climax with a mass discharge rate of 3.2 106 kg/s. Intense fracturing and fault activation favored entry of a significant amount of water into the system, which produced explosions driven by variably efficient water-magma interaction. These explosions generated wet to dry surge deposits that emplaced Member B and C, respectively. Isopachs and isopleths maps, as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a NE oriented, 2 km long fissure. The total volume of magma extruded during the eruption has been estimated at about 0.07 km3 (DRE). The erupted products range in composition from initial, weakly peralkaline alkali-trachyte, to last-emplaced alkali-trachyte. Isotopic data and modeling suggest that mixing occurred during the Averno 2 eruption between a more evolved, less radiogenic stored magma, and a less evolved, more radiogenic magma</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.3356C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3356C"><span>Geochemical data, geophysical signals and physical simulations of the hydrothermal system highlight the beginning of a new volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chiodini, Giovanni; Avino, Rosario; Caliro, Stefano; Mangiacapra, Annarita; De Martino, Prospero; Petrillo, Zaccaria; Cardellini, Carlo</p> <p>2013-04-01</p> <p>The temporal variation of magmatic fluid release at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is investigated using numerical simulations of the hydrothermal system constrained by diffuse CO2 emission data and by the chemical composition of fumarolic vents. The main aim is to understand the recent dynamics of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, where hundreds of thousands of people live in an area subjected since the middle of the 20th century to a long term crisis characterized by several episodes of ground uplift and correspondent seismic swarms (bradyseism). In 1998, the first measurements of diffuse degassing from the Solfatara crater, the most active zone of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, revealed the very intense release of hydrothermal- magmatic CO2 (~1500 t/d) and of thermal energy (~100 MW) highlighting that the expulsion of deep fluids is the main form of energy loss from the entire <span class="hlt">caldera</span> and suggesting an important role of magma degassing during the crisis. The hydrothermal system of Solfatara recently underwent large changes, including compositional variations of fumarolic effluents, compositional homogenization of the fluid released at different vents, changes in the pattern of diffuse degassing, increases in the pressures of the system, and increases in the temperature and in the flow rate of the fumaroles. Furthermore, after 20 yr of subsidence, an uplift period started in 2005. Comparing long-term series of geochemical signals with ground deformation and seismicity, we show that these changes are at least partially caused by repeated injections of magmatic fluid into the hydrothermal system. The frequency of these degassing episodes has increased in the last years, causing pulsed uplift episodes and swarms of low magnitude earthquakes. Modeling of these injection events allowed us to derive synthetic time series of geochemical parameters which well match those independently derived for the fumaroles. Total injected fluid masses in the simulated events are of the same order of magnitude as those emitted</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8318T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8318T"><span>Multiphysics numerical models of resurgent <span class="hlt">calderas</span> ground deformation: The 1982-2010 <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Southern Italy) case studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tizzani, Pietro</p> <p>2013-04-01</p> <p>Ground deformation signals in <span class="hlt">caldera</span> region are the expression of near-surface and/or deep-seated physical processes. As most of the geophysical analysis, the interpretation of the deformation data is usually performed setting up inverse problems, which often use Monte Carlo optimization techniques like the Simulated Annealing and the Genetic Algorithm, in order to constrain the nature of the causative sources at depth. Usually, these methods exploit the problem's solution space by iterating forward analytical models, which consider simplified geometries and homogeneous linear elastic material properties. However, several recent studies have shown that oversimplified forward models may lead to misinterpretations of the retrieved source parameters. To overcome these limitations we consider the Finite Element (FE) method as a powerful numerical tool that allows implementing models with complex geometries, material heterogeneities, as well as time dependent physical processes. For this reason, FE models are a suitable candidate to fill the gap between the accuracy achieved on the observation of ground deformation in volcanic areas and the models used for its interpretation. In this context, we investigate the driving forces responsible of the long-term ground deformation of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (CF) <span class="hlt">caldera</span>, Southern Italy, during the 1982-2010 time interval. To this purpose, we propose a new multiphysics numerical model that takes into account both the mechanical heterogeneities of the crust and the thermal conditions of geothermal system beneath the volcano. We perform a numerical Chain Rule Optimization Procedure (CROP) in a FEM environment, that considers different physical contexts linked along a common evolution line: starting from the thermal proprieties and mechanical heterogeneities of the upper crust, we develop a 3D time dependent thermo-fluid dynamic model of CF <span class="hlt">caldera</span>. More specifically, by carrying out two subsequent optimization procedures based on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816366U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816366U"><span>Probabilistic tsunami hazard assessment related to underwater explosions in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>: Gulfs of Napoli and Pozzuoli (Tyrrhenian Sea, Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ulvrova, Martina; Selva, Jacopo; Paris, Raphael; Brizuela, Beatriz; Costa, Antonio; Grezio, Anita; Lorito, Stefano; Tonini, Roberto</p> <p>2016-04-01</p> <p>Tsunami caused by underwater volcanic explosions are typically characterized by short period waves and greater dispersion compared to tsunami generated by earthquakes, and the impact in the far-field is often limited. However, the effect of dispersion is reduced for underwater explosions occurring in shallow-water environments, as the length-to-depth ratio of the waves rapidly increase, and runup inland can be locally high. This effect was particularly illustrated by the 19 m runup at Karymsky Lake, Kamchatka, in 1996 (Belousov et al., 2010; Ulvrova et al., 2014). Hazards related to underwater volcanic explosions are challenging to evaluate and might be underestimated in some cases. In this study we consider different scenarios of explosions in the offshore part of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Phlegraean Fields) <span class="hlt">caldera</span> in the Pozzuoli - Naples region (Tyrrhenian Sea, Italy). The onshore eruptive history of the <span class="hlt">caldera</span> is well documented (e.g. Orsi et al., 2004), but past and future activity offshore has been rarely discussed. The probability for eruptions in the submarine part of the <span class="hlt">caldera</span> is perhaps low (Selva et al., 2012), but scenarios of tsunamis generated by underwater explosions and their impact in the proximal field (Bay of Pozzuoli) and far field (Bay of Naples) deserve to be considered due to high population density in the adjacent coastal areas. Initial surface displacement is estimated as a function of explosion energy at a given depth. We study 17 different potential vent locations within the Pozzuoli Bay, and 3 different vent radii (200 m, 650 m and 900 m), corresponding to the three representative eruptive scenarios identified in Orsi et al. (2009) and Selva et al. (2010). We then use these sources in a Bayesian Event Tree framework, following the procedure defined in Selva et al. (2010), in order to evaluate a first order Probabilistic Hazard Analysis for this type of tsunami sources for the Gulfs of Napoli and Pozzuoli. Belousov A., Voight B., Belousova M</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917290I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917290I"><span>Multidisciplinary study (CO2 flux, ERT, self-potential, permeability and structural surveys) in Fondi di Baia, Astroni and Agnano volcanoes: insights for the structural architecture of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isaia, Roberto; Carapezza, Maria Luisa; Conti, Eric; Giulia Di Giuseppe, Maria; Lucchetti, Carlo; Prinzi, Ernesto; Ranaldi, Massimo; Tarchini, Luca; Tramparulo, Francesco; Troiano, Antonio; Vitale, Stefano; Cascella, Enrico; Castello, Nicola; Cicatiello, Alessandro; Maiolino, Marco; Puzio, Domenico; Tazza, Lucia; Villani, Roberto</p> <p>2017-04-01</p> <p>Recent volcanism at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> produced more than 70 eruptions in the last 15 ka formed different volcanic edifices. The vent distribution was related to the main volcano-tectonic structure active in the <span class="hlt">caldera</span> along which also concentrated part of the present hydrothermal and fumarolic activity, such as in the Solfatara area. In order to define the role of major faults in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span>, we analyzed some volcanic craters (Fondi di Baia and Astroni) and the Agnano <span class="hlt">caldera</span>, by means of different geochemical and geophysical technics including CO2 flux, electrical resistivity (ERT), self-potential and permeability surveys. We provided some ERT profiles and different maps of geochemical and geophysical features. Major fault planes were identified comparing ERT imaging with alignments of anomalies in maps. The results can improve the knowledge on the present state of these volcanoes actually not fully monitored though included in the area with high probability of future vent opening within the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4538569','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4538569"><span>Magma injection beneath the urban area of Naples: a new mechanism for the 2012–2013 volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>D’Auria, Luca; Pepe, Susi; Castaldo, Raffaele; Giudicepietro, Flora; Macedonio, Giovanni; Ricciolino, Patrizia; Tizzani, Pietro; Casu, Francesco; Lanari, Riccardo; Manzo, Mariarosaria; Martini, Marcello; Sansosti, Eugenio; Zinno, Ivana</p> <p>2015-01-01</p> <p>We found the first evidence, in the last 30 years, of a renewed magmatic activity at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> from January 2012 to June 2013. The ground deformation, observed through satellite interferometry and GPS measurements, have been interpreted as the effect of the intrusion at shallow depth (3090 ± 138 m) of 0.0042 ± 0.0002 km3 of magma within a sill. This interrupts about 28 years of dominant hydrothermal activity and occurs in the context of an unrest phase which began in 2005 and within a more general ground uplift that goes on since 1950. This discovery has implications on the evaluation of the volcanic risk and in the volcanic surveillance of this densely populated area. PMID:26279090</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...513100D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...513100D"><span>Magma injection beneath the urban area of Naples: a new mechanism for the 2012-2013 volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>D'Auria, Luca; Pepe, Susi; Castaldo, Raffaele; Giudicepietro, Flora; Macedonio, Giovanni; Ricciolino, Patrizia; Tizzani, Pietro; Casu, Francesco; Lanari, Riccardo; Manzo, Mariarosaria; Martini, Marcello; Sansosti, Eugenio; Zinno, Ivana</p> <p>2015-08-01</p> <p>We found the first evidence, in the last 30 years, of a renewed magmatic activity at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> from January 2012 to June 2013. The ground deformation, observed through satellite interferometry and GPS measurements, have been interpreted as the effect of the intrusion at shallow depth (3090 ± 138 m) of 0.0042 ± 0.0002 km3 of magma within a sill. This interrupts about 28 years of dominant hydrothermal activity and occurs in the context of an unrest phase which began in 2005 and within a more general ground uplift that goes on since 1950. This discovery has implications on the evaluation of the volcanic risk and in the volcanic surveillance of this densely populated area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26279090','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26279090"><span>Magma injection beneath the urban area of Naples: a new mechanism for the 2012-2013 volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>D'Auria, Luca; Pepe, Susi; Castaldo, Raffaele; Giudicepietro, Flora; Macedonio, Giovanni; Ricciolino, Patrizia; Tizzani, Pietro; Casu, Francesco; Lanari, Riccardo; Manzo, Mariarosaria; Martini, Marcello; Sansosti, Eugenio; Zinno, Ivana</p> <p>2015-08-17</p> <p>We found the first evidence, in the last 30 years, of a renewed magmatic activity at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> from January 2012 to June 2013. The ground deformation, observed through satellite interferometry and GPS measurements, have been interpreted as the effect of the intrusion at shallow depth (3090 ± 138 m) of 0.0042 ± 0.0002 km(3) of magma within a sill. This interrupts about 28 years of dominant hydrothermal activity and occurs in the context of an unrest phase which began in 2005 and within a more general ground uplift that goes on since 1950. This discovery has implications on the evaluation of the volcanic risk and in the volcanic surveillance of this densely populated area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26PSL.272..181A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.272..181A"><span>Simultaneous inversion of deformation and gravity changes in a horizontally layered half-space: Evidences for magma intrusion during the 1982 1984 unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amoruso, A.; Crescentini, L.; Berrino, G.</p> <p>2008-07-01</p> <p>A very large uplift (about 1.8 m) occurred in the period 1982-1984 at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Italy, without culminating in an eruption. A still-standing controversy accompanies the interpretation of deformation and gravity changes recorded during the unrest, which were interpreted to result from the sub-surface magmatic reservoir by some authors and from the hydrothermal system or hybrid sources by others. Here for the first time we take into account crustal layering while inverting leveling, EDM, and gravity data using uniformly-pressurized sources, namely small vertical spheroids and finite horizontal penny-shaped sources. The weight of EDM data in the misfit function is chosen from a trade-off curve in order to balance the compromise between fitting the leveling and the EDM data well. Models using a homogeneous medium cannot give a good simultaneous fit to leveling and EDM deformation data of the 1982-1984 unrest, whereas incorporating a layered structure (determined from seismically derived estimates of the P wave speed for the crust, and not adjusted to improve the fit in any of the inversions) allows a significantly better fit. Also, layering affects the sub-surface mass redistribution effects on gravity changes, and we show that the retrieved intrusion density is in full agreement with densities for highly evolved magmas expected at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> for depths of 3 to 4 km, ruling out hydrothermal fluids as the primary cause of the 1982-1984 unrest. The source of the 1982-1984 CF unrest was probably a shallow (about 3-km deep) penny-shaped magma intrusion fed by a deeper magma chamber; source overpressure was few MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816415N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816415N"><span>MED SUV TASK 6.3 Capacity building and interaction with decision makers: Improving volcanic risk communication through volcanic hazard tools evaluation, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> case study (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nave, Rosella; Isaia, Roberto; Sandri, Laura; Cristiani, Chiara</p> <p>2016-04-01</p> <p>In the communication chain between scientists and decision makers (end users), scientific outputs, as maps, are a fundamental source of information on hazards zoning and the related at risk areas definition. Anyway the relationship between volcanic phenomena, their probability and potential impact can be complex and the geospatial information not easily decoded or understood by not experts even if decision makers. Focusing on volcanic hazard the goal of MED SUV WP6 Task 3 is to improve the communication efficacy of scientific outputs, to contribute in filling the gap between scientists and decision-makers. <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, in Neapolitan area has been chosen as the pilot research area where to apply an evaluation/validation procedure to provide a robust evaluation of the volcanic maps and its validation resulting from end users response. The selected sample involved are decision makers and officials from Campanian Region Civil Protection and municipalities included in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> RED ZONE, the area exposed to risk from to pyroclastic currents hazard. Semi-structured interviews, with a sample of decision makers and civil protection officials have been conducted to acquire both quantitative and qualitative data. The tested maps have been: the official <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> RED ZONE map, three maps produced by overlapping the Red Zone limit on Orthophoto, DTM and Contour map, as well as other maps included a probabilistic one, showing volcanological data used to border the Red Zone. The outcomes' analysis have assessed level of respondents' understanding of content as displayed, and their needs in representing the complex information embedded in volcanic hazard. The final output has been the development of a leaflet as "guidelines" that can support decision makers and officials in understanding volcanic hazard and risk maps, and also in using them as a communication tool in information program for the population at risk. The same evaluation /validation process</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016644','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016644"><span>History of earthquakes and vertical ground movement in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Southern Italy: comparison of precursory events to the A.D. 1538 eruption of Monte Nuovo and of activity since 1968</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dvorak, J.J.; Gasparini, P.</p> <p>1991-01-01</p> <p>The record of felt earthquakes around Naples Bay in southern Italy is probably complete since the mid-15th century. According to this record, intense earthquake swarms originating beneath <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, an explosive <span class="hlt">caldera</span> located along the north coast of Naples Bay, have occurred only twice: (1) before the only historical eruption in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> in 1538; and (2) from mid-1983 to December 1984. Earthquake activity during the earlier period, which began at least a few years, and possibly as many as 30 years, before the 1538 eruption, damaged many buildings in the city of Pozzuoli, located near the center of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. Minor seismic activity, which consisted of only a few felt earthquakes, occurred from 1970 to 1971. The second period of intense earthquake swarms lasted from mid-1983 to 1984, again damaging many buildings in Pozzuoli. Two periods of uplift along the shoreline within <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> have also been noted since the mid-15th century: (1) during the few decades before the 1538 eruption; and (2) as two distinct episodes since 1968. Uplift of a few meters probably occurred a few decades before the 1538 eruption; uplift of as much as 3.0 m has occurred in Pozzuoli since 1968. These similarities strongly suggest that, for the first time in 440 years, the same process that caused intense local earthquake swarms and uplift in the early 1500's and led to an eruption in 1538, has again occurred beneath <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. Though no major seismicity or uplift has occurred since December 1984, because of the large amount of extensional strain accumulated during the past two decades, if a third episode of seismicity and rapid uplift occurs, it may lead to an eruption within several months after the resumption of activity. ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1879D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1879D"><span>Interferometric imaging of the 2011-2013 <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Nakahara, Hisashi; Zaccarelli, Lucia; Sammarco, Carmelo; La Rocca, Mario; Bianco, Francesca</p> <p>2017-04-01</p> <p>After its 1983-84 seismic and deformation crisis, seismologists have recorded very low and clustered seismicity at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy). Hence, noise interferometry imaging has become the only option to image the present volcano logical state of the volcano. Three-component noise data recorded before, during, and after <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> last deformation and geochemical unrest (2011-2013) have thus been processed with up-to-date interferometric imaging workflow based on MSNoise. Noise anisotropy, which strongly affects measurements throughout the <span class="hlt">caldera</span> at all frequencies, has been accounted for by self-correlation measurements and smoothed by phase weighted stacking and phase-match filtering. The final group-velocity maps show strong low-velocity anomalies at the location of the last <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> eruption (1538 A.D.). The main low-velocity anomalies contour Solfatara volcano and follow geomorphological cross-faulting. The comparison with geophysical imaging results obtained during the last seismic unrest at the <span class="hlt">caldera</span> suggest strong changes in the physical properties of the volcano, particularly in the area of major hydrogeological hazard.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V13D2885S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V13D2885S"><span>Timescales of magma residence at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, V. C.; Saunders, K.; Isaia, R.</p> <p>2012-12-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> has produced many large explosive eruptions, including the largest in Europe in the last 200 kyrs. There have been more than 60 violent Strombolian-Vulcanian through to Plinian eruptions in the last 15 kyrs. Recent changes in ground displacement and composition of fumarole fluids indicate the <span class="hlt">caldera</span> is still active and suggest that magma resides in the upper crust (Chiodini et al., 2012). Here we used zoned crystals within the post-15 ka eruption deposits to assess the timescales of upper crustal magma residence at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. We present details of the major and trace element composition of the crystals, and diffusion chronometry results. These data provide detail on the crystallisation timescales and the changing nature of the magmatic system. It is clear that the magmas that fuel the eruptions are assembled in an open system and that upper crustal residence for most of the melt is short. Chiodini, G., Caliro, S., De Martino, P., Avino, R., Gherardi, F. 2012. Early signals of new volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>? Insights from geochemical data and physical simulations. Geology. http://dx.doi.org/10.1130/G33251.1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JVGR..133..171I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JVGR..133..171I"><span>The Astroni volcano: the only example of closely spaced eruptions in the same vent area during the recent history of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isaia, Roberto; D'Antonio, Massimo; Dell'Erba, Francesco; Di Vito, Mauro; Orsi, Giovanni</p> <p>2004-05-01</p> <p>The Astroni volcano formed during the third and most recent epoch of activity (4.8-3.8 ka) of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc). The activity of the volcano was dominated by explosive, mostly phreatomagmatic eruptions, with only subordinate lava effusions. We have grouped the sequence of deposits into seven distinct units, separated by erosional unconformities or very thin paleosols. The units include mostly surge beds, with subordinate strombolian deposits and lavas, and one plinian fallout layer. The total volume of erupted magma is 0.45 km 3 (DRE), while the total mass is 1.12×10 12 kg. The magma feeding the first five eruptions was alkali-trachytic and slightly zoned, while the last two eruptions tapped a magma batch resulting from mixing of the previously extruded alkali-trachytic and a less evolved trachytic magma. The volcano grew at the northwestern edge of the polygonal volcano-tectonic collapse, northwest-southeast elongated, which accompanied the Agnano-Monte Spina eruption (4.1 ka), the largest of the third epoch. Available radiometric dates and stratigraphical data constrain the age of the volcano in the final part of the 4.1-3.8 ka time span. This implies that the seven eruptions followed each other at very short time intervals. This conclusion is also supported by constancy in archaeological facies of findings within the paleosols between variable Astroni units, in the plain north of the <span class="hlt">caldera</span>. The sequence of close eruptions in the same area, although with a slight migration of the vent from northwest to southeast, makes the Astroni volcano peculiar in the recent history of the CFc. Therefore, the definition of its history is very important in order to understand one of the past phenomenologies of the <span class="hlt">caldera</span>, relevant elements to forecast its behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8492S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8492S"><span>Comparison between temperatures pattern from thermal IR time series analisys and deformational pattern from InSAR and GPS data at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Naples, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sansivero, F.; Vilardo, G.; Borgstrom, S.; De Martino, P.; Siniscalchi, V.; Minet, C.; Goel, K.</p> <p>2012-04-01</p> <p>Long-term thermal infrared volcanological monitoring is carried out at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Naples, Italy) by INGV - Osservatorio Vesuviano by acquiring daily infrared images (LWIR) of fumaroles fields since year 2004. The IR monitoring system (TIIMNet -Thermal Infrared Monitoring Network) includes two permanent automatic infrared (IR) stations installed at Solfatara crater and at Pisciarelli area equipped both with a NEC Thermo Tracer TS7302 IR camera with focal plane array (FPA) uncooled microbolometer measuring systems (320x240 pixel). At Solfatara the station is operative since July 2004 and acquires scenes of the SE inner slope of Solfatara where are located the major fumaroles at an average distance of about 300 m from the IR camera. The camera at Pisciarelli is operative since October 2006 and acquires scenes of the outer eastern flank of the Solfatara tuff-cone (average distance of fumaroles is about 130 m), corresponding to an area characterized by heavy water vapor and CO2 emissions. To obtain as much as possible accurate temperature values which can be representative of surface temperatures of fumaroles fields, time series of raw IR scenes has been processed with integrated methodologies. Briefly these methodologies are based on Standard Deviation filtering (as SD represents a quality parameter), background correction of the temperature values and periodicities removal using Matlab tools. The data representation, using an average moving window, show a pattern without evidence of the major seasonal cyclicity, although it still contains minor cyclicity probably due to endogenous factors and, particularly at Pisciarelli, it evidences significant temperature peak values on August 2009 and a gradual increase of temperatures from November 2010 till now. In order to strengthen the significance of data from IR thermal analysis, a comparison with deformational pattern has been carried out using both High-Resolution Spotlight TerraSAR-X data, processed using the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918699M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918699M"><span>The types of unrest occurring at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Southern Italy) since 1982 and the role of magma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moretti, Roberto; De Natale, Giuseppe; Sarno, Federica; Schiavone, Roberto; Troise, Claudia</p> <p>2017-04-01</p> <p>The thermodynamic response of a multiphase (at least biphasic) and multicomponent system that has enough degrees of freedom to respond to variations of external constraints consists in re-equilibrating phase proportions and compositions of dissolved components. For volcanic systems in unrest, such as <span class="hlt">CampiFlegrei</span>, this puts first-order thermal constraints that typically the procedures of geophysical inversion of geodetic and gravimetric data cannot identify.In this study, based on a thermodyamically internally consistent approach to the geochemical data recorded in the last 35 years, we show that: 1) The fumarole-feeding portions of the Solfatara geothermal field have fluid pressures below the lithostatic gradients. Shallow steam condensation occurs certainly in the surroundingsof fumarole emissions, and was attained in few circumstances during the 1982-84 unrest. 2) Inert gases help evaluating the geochemical signature of the deep upcoming gas, not compatible with a magma migrating to shallow depths in recent times. Any magma emplaced at shallow depth should have a volatile content and a size incompatible with geophysical measurements and models on shallow magma emplacement.After exhaustion of the shallow magma emplaced in1982-84, the system is fed by a deep magmatic gas. 3) Gas indicators and the observed increase in magmatic fraction (Y) after year 2000 require a raise in the temperature of the formed hydrothermal vapour and the likely involvement of a supercritical fluid phase. This determines the opening of awindow for magmatic gases at surface, which is however hardly compatible with a magma raising to shallow depths. 4) The unrest style can be related to the P-T-H conditions of the deep hydrothermal vapour. These determine if the pore-filling fluid is a biphasic liquid+vapour. like in 1982-84, when pore overpressures developed under nearly undrained conditions. 5) The nature of the 1982-84 unrest was magmatic, due to the emplacement of a shallow (3-4 km deep</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1882D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1882D"><span>Seismic imaging of the hot source of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Chiodini, Giovanni; Vilardo, Giuseppe; Del Pezzo, Edoardo; Castellano, Mario; Colombelli, Simona; Tisato, Nicola; Ventura, Guido</p> <p>2017-04-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is the site of the largest volcanic eruption in Europe during the past 100,000 years. Here, we propose a novel seismic attenuation and lapse-time source model supported by interdisciplinary data, which image the structures and dynamics active at the <span class="hlt">caldera</span> with enhanced interpretational potential. The deepest anomaly in our model is a 4-5 km deep, NNW-SSE striking, aseismic hot zone offshore the city of Pozzuoli, active during the main seismic and deformation unrest of the <span class="hlt">caldera</span> (1983-84). The hot zone is either a magma sill/fluid reservoir or the high-absorption top of of a molten domain, it feeds a reservoir of supercritical fluids/foams topping at a depth of about 3 km, and produces strong absorption, detected by 2D absorption mapping. Seismic activity, gravimetric anomalies, geomorphology, and geochemical data all confirm that the structure produces time-dependent pulses opening cracks in the generally aseismic western portion of the <span class="hlt">caldera</span>, thus following the pattern of magma transfer active during the last eruption of the <span class="hlt">caldera</span>, and stopping the unrest. After 1984, seismic activity oat <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> has almost stopped due to changes in this deep feeding structure, which, as remote sensing data show, is still active today.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..940C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..940C"><span>3D image of Brittle/Ductile transition in active volcanic area and its implication on seismicity: The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> case study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castaldo, Raffaele; Luca, D'auria; Susi, Pepe; Giuseppe, Solaro; Pietro, Tizzani</p> <p>2015-04-01</p> <p>The thermo-rheology of the rocks is a crucial aspect to understand the mechanical behavior of the crust in young and tectonically active area. As a consequence, several studies have been performed since last decades in order to understand the role of thermic state in the evolution of volcanic environments. In this context, we analyze the upper crust rheology of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> active <span class="hlt">caldera</span> (Southern Italy). Our target is the evaluation of the 3D geometry of the Brittle-Ductile transition beneath the resurgent <span class="hlt">caldera</span>, by integrating the available geological, geochemical, and geophysical data. We first performed a numerical thermal model by using the a priori geological and geophysical information; than we employ the retrieved isothermal distribution to image the rheological stratification of the shallow crust beneath <span class="hlt">caldera</span>. In particular, considering both the thermal proprieties and the mechanical heterogeneities of the upper crust, we performed, in a Finite Element environment, a 3D conductive time dependent thermal model through an numerical of solution of the Fourier equation. The dataset consist in temperature measurements recorded in several deep wells. More specifically, the geothermal gradients were measured in seven deep geothermal boreholes, located in three main distinct areas: Mofete, Licola, and San Vito. In addition, we take into account also the heat flow density map at the <span class="hlt">caldera</span> surface calculated by considering the thermal measurements carried out in 30 shallow water wells. We estimate the isothermal distribution of the crust calibrating two model parameters: the heat production [W], associated to the magma injection episodes in the last 60 kyears within the magma chamber and the heat flow coefficient [W/m2*K] at the external surface. In particular, the optimization procedure has been performed using an exhaustive grid search, to minimize the differences between model and experimental measurements. The achieved results allowed us to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010BVol..tmp..119G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010BVol..tmp..119G"><span>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 uc(ad))</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guidoboni, Emanuela; Ciuccarelli, Cecilia</p> <p>2010-12-01</p> <p>This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36 hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive crisis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011BVol...73..655G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011BVol...73..655G"><span>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 AD)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guidoboni, Emanuela; Ciuccarelli, Cecilia</p> <p>2011-08-01</p> <p>This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36?| hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BVol...79...18I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BVol...79...18I"><span>Timescales of magmatic processes prior to the ˜4.7 ka Agnano-Monte Spina eruption (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Southern Italy) based on diffusion chronometry from sanidine phenocrysts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iovine, Raffaella Silvia; Fedele, Lorenzo; Mazzeo, Fabio Carmine; Arienzo, Ilenia; Cavallo, Andrea; Wörner, Gerhard; Orsi, Giovanni; Civetta, Lucia; D'Antonio, Massimo</p> <p>2017-02-01</p> <p>Barium diffusion chronometry applied to sanidine phenocrysts from the trachytic Agnano-Monte Spina eruption (˜4.7 ka) constrains the time between reactivation and eruption of magma batches in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. Backscattered electron imaging and quantitative electron microprobe measurements on 50 sanidine phenocrysts from representative pumice samples document core-to-rim compositional zoning. We focus on compositional breaks near the crystal rims that record magma mixing processes just prior to eruption. Diffusion times were modeled at a magmatic temperature of 930 °C using profiles based on quantitative BaO point analyses, X-ray scans, and grayscale swath profiles, yielding times ≤60 years between mixing and eruption. Such short timescales are consistent with volcanological and geochronological data that indicate that at least six eruptions occurred in the Agnano-San Vito area during few centuries before the Agnano-Monte Spina eruption. Thus, the short diffusion timescales are similar to time intervals between eruptions. Therefore, the rejuvenation time of magma residing in a shallow reservoir after influx of a new magma batch that triggered the eruption, and thus pre-eruption warning times, may be as short as years to a few decades at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5043S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5043S"><span>Aseismic strain episodes at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarpa, Roberto; Amoruso, Antonella; Bilham, Roger; Di Lieto, Bellina; Errico, Antonio; Linde, Alan; Sacks, Selwyn</p> <p>2014-05-01</p> <p>Since spring 2004 a research project has been developed in Italy to install borehole Sacks-Evertson strainmeters (dilatometers) aimed to improve monitoring systems of the Italian volcanoes. 6 borehole dilatometers have been installed around <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius during 2004-2005 (Scarpa et al., 2007). This small network has been implemented by two arrays of long-baseline water tube tiltmeters installed in underground tunnels since 2008. Relevant strainmeter and tiltmeter data have been collected and analyzed at the instruments installed at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> during the recent unrest episodes. Renewed activity started since 2004-2005, characterized by a quite low rate of vertical vertical displacement, amounting initially to a few cm/year. A long term strain episode occurred during summer 2006, in correspondence to an increase of CO2 emission and displacements measured also by tiltmeters and GPS transducers. This strain episode preceded the seismic activity by few months, as also observed during the 1982 most significant unrest. Other aseismic slip episodes have been recorded in 2009, in correspondence of the renewal of gas emission activity at Solfatara, in 2010, one day before a seismic swarm, and in September 2012, few days before the most significant seismic swarm occurred after the 1982-1984 uplift. The time scale of these phenomena is ranging from some hours to several days, putting further constraints on the origin of ground uplifts at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. Their location is compatible with the source inferred from long term deformation signals, at about 4 km depth beneath Pozzuoli.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712823M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712823M"><span>Mineralogical and sulfur isotopic characterization of the sulfur-bearing mineralization from the active degassing area of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mormone, Angela; Piochi, Monica; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe</p> <p>2015-04-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is a site of persistent hydrothermal circulation and gaseous emissions inside the Pozzuoli town and nearby the city of Napoli (Italy). The solfataric phenomena are associated with episodes of low-magnitude seismicity and vertical ground displacement since Roman times, evolving to the Monte Nuovo eruption in the 1538 AD. Pronounced geochemical anomalies, uplift rates up to 1 m/y and up to ten thousands microearthquakes per year also characterized the four most recent decades of unrest. The degassing phenomena are concentrated within the Solfatara crater, although, since 2006, the hydrothermal activity strongly increased in the Pisciarelli district, i.e. on the north-east slope of the tuff. We investigated sulfur-bearing mineral precipitates sampled from the active fumaroles both within the Solfatara and along the Pisciarelli slope. Mineral assemblage, texture and chemistry were determined for the efflorescence precipitated nearby the fumaroles and along the mud pool by x-ray diffraction, back-scattered electron microscope and electron diffuse microanalysis. δ34S compositions were also determined on separated sulfur-minerals. The new data have been compared with scattered literature data, including few existing for the previous '70 and '80 unrest episodes. Native sulfur and alunite are the main mineral phases that associate with alunogene, and, locally, pickeringite and potassium alum. Sporadically mereiterite, amarillite, and pyrite have been found as neogenesis mineralization along the outcropping rocks. The mud pool is rich in gypsum, potassium alum and pyrite. δ34S values range from -5.48 to 0.0‰, being slightly lower than previous data. The obtained results suggest that the Pisciarelli area is characterized by magmatic-hydrothermal, magmatic-steam and steam-heated environments, developed on a argillitic hydrothermal facies that thickens in correspondence of the degassing area. These environments develop and continuously evolve in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007EOSTr..88..197S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007EOSTr..88..197S"><span>New Borehole Strain System Detects Uplift at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarpa, Roberto; Amoruso, Antonella; Crescentini, Luca; Romano, Pierdomenico; De Cesare, Walter; Martini, Marcello; Scarpato, Giovanni; Linde, Alan T.; Sacks, Selwyn I.</p> <p>2007-05-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Mount Vesuvius are active Italian volcanoes though presently in a quiescent stage. The last eruption of Mount Vesuvius occurred during the spring of 1944. <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> last erupted in 1538 but experienced a subsidence trend from the early 1900s to 1970, which was followed by episodes of ground uplift accompanied by seismic swarms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BVol...79...67P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BVol...79...67P"><span>The Baia-Fondi di Baia eruption at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>: stratigraphy and dynamics of a multi-stage <span class="hlt">caldera</span> reactivation event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pistolesi, Marco; Bertagnini, Antonella; Di Roberto, Alessio; Isaia, Roberto; Vona, Alessandro; Cioni, Raffaello; Giordano, Guido</p> <p>2017-09-01</p> <p>The Baia-Fondi di Baia eruption is one of the sporadic events that have occurred in the western sector of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. It dates back to 9525-9696 bp and opened Epoch 2 of the <span class="hlt">caldera</span> activity after a 1000-year-long period of quiescence. Although relatively small in terms of erupted volume with respect to most of the events of the past 15 ka, the Baia-Fondi di Baia eruption was characterized by a complex series of events, which have led to different interpretations in the literature. We present a detailed stratigraphic study of 40 outcrops in a sector of about 90 km2, coupled with sedimentological (grain size, componentry), physical (density, vesicularity), textural, and compositional analyses of the erupted deposits. Based on these data, we interpret the stratigraphic succession as being related to two distinct eruptive episodes (Baia and Fondi di Baia). These were separated by a short time interval, and each was characterized by different eruptive phases. The Baia eruptive episode started in a shallow-water environment with an explosive vent-opening phase that formed a breccia deposit (Unit I), rapidly followed by alternating fallout activity and dense, pyroclastic density current deposits generation (Unit II). Sedimentological features and pumice textural analyses suggest that deposition of Unit II coincided with the intensity peak of the eruption, with the fallout deposit being characterized by a volume of 0.06 ± 0.008 km3 (corresponding to a total erupted mass of 4.06 ± 0.5 × 1010 kg), a column height of 17 km, and a corresponding mass flow rate of 1.8 × 107 kg s-1. The associated tephra also shows the highest vesicularity (up to 81 vol.%) the highest vesicle number density (1.01 × 108 cm-3) and decompression rate (0.69 MPa s-1). This peak phase waned to turbulent, surge-like activity possibly associated with Vulcanian explosions and characterized by progressively lower intensity, as shown by density/vesicularity and textural properties of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3009D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3009D"><span>Frequency-dependent seismic coda-attenuation imaging of volcanic geomorphology: from debris flows at Mount St. Helens volcano to cross-faulting at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Gabrielli, Simona; Spagnolo, Matteo</p> <p>2017-04-01</p> <p>The stochastic loss of energy measured using the later portion of seismic recordings (coda) can be used to image and monitor geomorphology in volcanoes, once appropriate sensitivity kernels for the application of attenuation tomography have been developed. The use of this advanced seismic method with GIS/InSAR techniques is an unexplored field, which is receiving increasing attention in volcano-seismology. By using this integrated approach we can image structure and monitor dynamics of the debris flow that followed the 1980 explosive eruption of Mount St. Helens (US) volcano at resolution similar to that of remote sensing data, and depths of <20 meters. When the volcano has not erupted, attenuation anomalies are instead spatially correlated with the regions of highest structural complexity and cross faulting. At <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, the results provide a novel perspective on the links between deep fluid migration and surface structures. The implications of the proposed approach on volcano monitoring are evident.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GeoRL..34.9303C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GeoRL..34.9303C"><span>Effects of crustal layering on the inversion of deformation and gravity data in volcanic areas: An application to the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crescentini, L.; Amoruso, A.</p> <p>2007-05-01</p> <p>We study the effects of crustal layering on ground displacements and gravity changes due to a spheroidal expanding source. Soft superficial layers affect the deformation pattern (giving an apparent shallower source if layering is not taken into account), the ratio of horizontal to vertical displacements (biasing the source shape), and the subsurface mass redistribution effects on gravity changes. Retrieved intrusion density is biased toward very low values if the source is modelled as a penny-shaped crack (point and finite) in a homogeneous half-space and the resulting density misestimate can lead to a possibly incorrect assessment of volcanic hazard. As an application, we consider the 1982-1984 <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> unrest. We show that the large discrepancy between densities of spherical and penny-shaped sources, given in the literature and obtained inverting ground displacement and gravity data in a homogeneous half-space, is at least partially a consequence of the homogeneous half-space assumption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210146V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210146V"><span>Physical properties of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> tuff from variable depths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vinciguerra, Sergio; Del Gaudio, Pierdomenico; Iarocci, Alessandro; Mollo, Silvio; Scarlato, Piergiorgio; Freda, Carmela</p> <p>2010-05-01</p> <p>A number of measurements on physical properties of volcanic tuff from different volcanic Italian districts (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Colli Albani, Lago di Vico) has been performed in the recent years. Petrophysical investigations carried out at increasing/decreasing effective pressure (Vinciguerra et al., 2005; 2008) revealed how, within the same lithology, the different degree of lithification and presence of clasts can affect significantly physical property values. Microstructural analyses revealed that the pressurization and depressurization cycles generate inelastic crack damage/pore collapse and permanent reduction of voids space. When cores from boreholes were investigated, significant variations of physical properties have been found even within the same tuff lithologies (Vinciguerra et al., 2008), which significantly influence the modelling of the overall physics and mechanics, as well as the input parameters for ground deformation and seismicity modelling. In this study we analysed the physical properties of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> tuff (12ka) cores from depths down to 100m, which is the most abundant and widely distributed lithology in the <span class="hlt">caldera</span> (Rosi and Sbrana, 1987). CF tuff is a strongly heterogeneous pyroclastic flow material, which include cavities, pumice and crystals of sanidine, pyroxene and biotite (Vanorio et al., 2002; Vinciguerra et al., 2005). Total porosity was measured, after drying samples at 80°C for 24 hours, throughout a helium pycnometer (AccuPyc II 1340, Micromeritics Company) with ±0.01% accuracy. Initial total porosity of 52% was found for cores coming from 30m of depth. Total porosity decreases to 46% , when cores from 100m depth are considered. Bench measurements of P-wave and S-wave velocities carried out in dry conditions are of 1.8 and 1.2 km/s respectively for the 30m depth cores and increase up to 2.1 km/s and 1.35 km/s at depth of 100m. Taken together, the measurements of porosity and seismic velocities of P and S wave velocities revealed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916115B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916115B"><span>Signature of magmatic processes in strainmeter records at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bagagli, Matteo; Montagna, Chiara P.; Papale, Paolo</p> <p>2017-04-01</p> <p>Volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is characterized by episodes of ground deformation, seismicity and enhanced fumarolic activity; whether its origin is purely hydrothermal or magmatic is highly debated. We have analyzed ground deformation patterns in strainmeter records, focusing on a heightened unrest period in late 2006. These data have been compared to synthetic signals obtained from simulations of shallow magma chamber replenishment and mixing at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. Our results show that discrete transients can be identified in the monitoring records, that strongly resemble the synthetics in both time and frequency domains, pointing to a magmatic contribution to the unrest. Together with other recent findings, our results depict a situation whereby periodic arrivals of deep magma feed a shallow intrusion at 3-4 km depth. These results suggest that the analysis of strainmeter records, coupled with advanced numerical simulations of magma dynamics, could lead to new approaches in imaging subsurface dynamic processes in volcanic areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JVGR..299...35M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JVGR..299...35M"><span>Hazard of pyroclastic density currents at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> (Southern Italy) as deduced from the combined use of facies architecture, physical modeling and statistics of the impact parameters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mele, D.; Dioguardi, F.; Dellino, P.; Isaia, R.; Sulpizio, R.; Braia, G.</p> <p>2015-06-01</p> <p>Pyroclastic density currents of the recent eruptions at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> (CFC - Southern Italy) have been studied with the aim of assessing the potential impact of similar events in the future. Eruptions of different scales have been investigated by means of the combined use of facies architecture, laboratory analysis and physical modeling. Both in the small (Averno 2) and intermediate (Astroni) scales, facies analysis indicates that deposits result from the emplacement of pyroclastic density currents like base-surge, formed by multiple closely-timed impulses of phreatomagmatic origin. In the large-scale event (Agnano-Monte Spina), the facies architecture suggests that the currents started as concentrated flows near the vent, as originating from the collapse of a dense eruptive column, and evolved laterally into expanded flows by the propagation of the basal shear current. Laboratory analyses on samples from the main layers of deposits allowed obtaining the input data for the PYFLOW code, which was used for reconstructing the flow dynamic characteristics of the currents. The expected damage is discussed in terms of the probability density function of dynamic pressure and particle volumetric concentration. In this way, the range of potential impact that similar pyroclastic density currents could cause to buildings, infrastructures and population is defined. In the large-scale event, the dynamic pressure ranges from 9.38 to 1.00 kPa (integrating the basal 10 m of the current) at distances of 1.5 and 4.0 km from the vent, respectively. The values are highly influenced by the local topography. In the intermediate-scale event, the dynamic pressure ranges from 2.43 to 0.26 kPa at distances of 1.1 and 1.4 km from the vent, respectively. In the small scale event, the dynamic pressure ranges from 1.49 to 0.39 kPa at distances of 0.5 and 1.1 km from the vent, respectively. The particle volumetric concentration at a height of 2 m within the current is always lower than 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915572D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915572D"><span>Magmatic processes evidenced by borehole dilatometer data at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Lieto, Bellina; Romano, Pierdomenico; Scarpa, Roberto; Orazi, Massimo</p> <p>2017-04-01</p> <p>Since spring 2004 a joint research project (AMRA, UniSa, INGV) has been developed in Italy to install borehole strainmeters aimed at enhanced INGV monitoring systems. Six Sacks-Evertson dilatometers were installed around <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius during 2004-2005, and in 2008 these were supplemented by two arrays of long-baseline underground water tube tiltmeters. Renewed activity started since 2004-2005, characterized by a low rate of vertical displacement, amounting initially to a few cm/year. Recent deformation in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is dominated by aseismic inflation, interrupted by minor transient aseismic reversals in rate. These are typically below the noise level or are poorly sampled by the low sampling frequency of most geodetic techniques, but can be quantified relatively easily using high sensitivity strainmeters and tiltmeters. These instruments provide coherent views of deformation at several different time scales capturing reversals in rate with periods from minutes to months. Monotonic uplift episodes have been recorded with durations of several weeks to a few years. During the summer of 2006 a long term strain episode related to an increase of CO2 emission, evidenced by borehole tiltmeters and continuous GPS sensors, has been observed by the borehole dilatometers array. This strain episode preceded <span class="hlt">caldera</span> microseismic activity by few months, as was also observed during the 1982 period of unrest. Other aseismic slip episodes were recorded in October 2006 and in March 2010, several minutes before the most significant seismic swarms (VT and/or LP events) occurred after the 1982-1984 uplift. The time scale of these transient strain events lasted less than one hour, putting further constraints on the origin of ground uplifts at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. Their locations are compatible with the source inferred from long term deformation signals, at about 4 km depth beneath Pozzuoli. The current array provides us with a glimpse of the potential utility of a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SolED...5.1081H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SolED...5.1081H"><span>The permeability and elastic moduli of tuff from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy: implications for ground deformation modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heap, M. J.; Baud, P.; Meredith, P. G.; Vinciguerra, S.; Reuschlé, T.</p> <p>2013-07-01</p> <p>The accuracy of ground deformation modelling at active volcanoes is a principal requirement in volcanic hazard mitigation. However, the reliability of such models relies on the accuracy of the rock physical property (permeability and elastic moduli) input parameters. Unfortunately, laboratory-derived values on representative rocks are usually rare. To this end we have performed a systematic laboratory study of the influence of pressure and temperature on the permeability and elastic moduli of the two most widespread tuffs from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic district, Italy. Our data show that the water permeability of Neapolitan Yellow Tuff and a tuff from the Campanian Ignimbrite differ by about two orders of magnitude, highlighting the heterogeneous nature of the tuffs at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. As pressure (depth) increases beyond the critical point for inelastic pore collapse (at an effective pressure of 10-15 MPa, or a depth of about 750 m), permeability and porosity decrease significantly, and ultrasonic wave velocities and dynamic elastic moduli increase significantly. Increasing the thermal stressing temperature increases the permeability and decreases the ultrasonic wave velocities and dynamic elastic moduli of the Neapolitan Yellow Tuff; whereas the tuff from the Campanian Ignimbrite remains unaffected. This difference is due the presence of thermally unstable zeolites within the Neapolitan Yellow Tuff. For both rocks we also find, under the same pressure conditions, that the dynamic (calculated from ultrasonic wave velocities) and static (calculated from triaxial stress-strain data) elastic moduli differ significantly. The choice of elastic moduli in ground deformation modelling is therefore an important consideration. While we urge that these new laboratory data should be considered in routine ground deformation modelling, we highlight the heterogeneous nature of the rocks that comprise the <span class="hlt">caldera</span> at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2647P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2647P"><span>Permeability of alkaline magmas: a study from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Polacci, M.; Bouvet de Maissoneuve, C.; Giordano, D.; Piochi, M.; Degruyter, W.; Bachmann, O.; Mancini, L.</p> <p>2012-04-01</p> <p>Knowledge of permeability is of paramount importance for understanding the evolution of magma degassing during pre-, syn- and post-eruptive volcanic processes. Most permeability estimates existing to date refer to magmas of calc-alkaline compositions. We report here the preliminary results of permeability measurements performed on alkali-trachyte products erupted from the Campanian Ignimbrite (CI) and Monte Nuovo (MTN), two explosive eruptions from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (CF), an active, hazardous <span class="hlt">caldera</span> west of Naples, Southern Italy. Darcian (viscous) permeability spans a wide range between 10^-11 and 10^-14 m^2. We observe that the most permeable samples are the scoria clasts from the upper units of MTN; pumice samples from the Breccia Museo facies of CI are instead the least permeable. Non-Darcian (inertial) permeability follows the same trend as Darcian permeability. The first implication of this study is that porosity in alkaline as well as calc-alkaline magmas does not exert a first order control on permeability (e.g. the MTN samples are the most permeable but not the most porous). Second, sample geometry exhibits permeability anisotropy (higher permeability in the direction of vesicle elongation), suggesting stronger degassing in the vertical direction in the conduit. In addition, inertial effects are higher across the sample. As inertial effects are potentially generated by tortuosity (or tortuous vesicle paths), tortuosity is likely higher horizontally than vertically in the conduit. Finally, the measured CF permeability values overlap with those of rhyolitic pumice clasts from the Kos Plateau Tuff (Bouvet de Maisonneuve et al., 2009), together with CI one of the major Quaternary explosive eruptions of the Mediterranean region. This indicates that gas flow is strongly controlled by the geometry of the porous media, which is generated by the bubble dynamics during magma ascent. Therefore, permeability will depend on composition through the rheological properties</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5776C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5776C"><span>A combined morphostructural/fluid migration model of Pisciarelli area (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> - CFc) through structural and integrated Terrestrial Laser Scanner (TLS) and Electrical Resistivity Tomography (ERT) analysis.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caputo, Teresa; Di Giuseppe, Maria Guilia; Troiano, Antonio; Somma, Renato; Isaia, Roberto; Vitale, Stefano; Troise, Claudia; De Natale, Giuseppe</p> <p>2014-05-01</p> <p>The Solfatara-Pisciarelli (S-P) area was characterized by an intense eruptive activity during the last 5 ka and is presently the highly distributed degassing zones inside the CFC, worldwide well-known for its bradyseismic phenomenon. The last two main crises occurred during the 1970-72 and 1982-84, associated with an overall 3.5 m of ground uplift and an elevate rate of low magnitude seismicity. A strong direct relationship has always been observed between the increase of hydrothermal activity in the S-P area and ground uplift of the CFc. More recently starting from the 2005 a new gradual increase of the hydrothermal activity and ground uplift has been observed, with a steep growth of these effects from 2012, accompanied by seismic events with highest magnitude of 1.8. The Pisciarelli area has been the site of a significant morphological changes of its hydrothermal field including new fumarolic vents and a wide enlargement of a mud pool. Monitoring either landscape deformation than fluids migration of the S-P activity can be considered a good indicator of the volcanic dynamics taking place in the whole CFc <span class="hlt">caldera</span>. This study shows a first attempt to integrate multidisciplinary approach including volcanological and structural field surveys and studies such us TLS and ERT signals applied to this highly dynamic areas. A detailed geo-structural survey allow us to characterize the complex pattern of fractures and faults recorded in the volcanic rocks in different times of the polyphasic CFc volcanic history. In order to statistically record data about fault and fracture (i) attitudes and (ii) spacing, the scan line method was applied. The whole planar structure is the locus of the well-known fumaroles and mud pools of Pisciarelli. A first time detailed Digital Terrestrial Model DTM of the area with an accuracy of 5cm obtained through TLS has been integrated combining the ERT of the lower part of the area, characterized by a widespread fumarolic activity and soil</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5080I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5080I"><span>Residence times of alkali feldspar phenocrysts from magma feeding the Agnano-Monte Spina Eruption (4.7 ka), <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Napoli, southern Italy) based on Ba-zonation modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iovine, Raffaella Silvia; Wörner, Gerhard; Carmine Mazzeo, Fabio; Arienzo, Ilenia; Fedele, Lorenzo; Civetta, Lucia; D'Antonio, Massimo; Orsi, Giovanni</p> <p>2016-04-01</p> <p>Timescales governing the development of crustal magma reservoirs are a key for understanding magmatic processes such as ascent, storage and mixing event. An estimate of these timescales can provide important constraints for volcanic hazard assessment of active volcanoes. We studied the Agnano-Monte Spina eruption (A-MS; 4.7 ka; VEI = 4; 0.85 km3 D.R.E. of magma erupted) of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, one of the most dangerous volcanic areas on Earth. The A-MS eruption has been fed by magmas varying from more to less evolved trachyte whose variable 87Sr/86Sr and trace elements features suggest magma mixing between two end-members. Ba zonation profiles of alkali feldspar phenocrysts have been determined through combined energy-dispersive and wavelength-dispersive electron microprobe analyses (EDS-WDS-EMPA). We focused on distinct compositional breaks near the rim of the crystals that likely represent the last mixing event prior to eruption. We always chose the steepest gradients close to the crystal rims, taking into account that any effects related to cutting angles or crystal orientation should give longer apparent diffusion times. Two different approaches were undertaken: (1) a quantitative Ba compositional profiles were measured by point analyses along a short transect crossing growth discontinuities and (2) grey-scale profiles were taken parallel to the acquired point profiles. Assuming that Ba dominates the backscattered electron intensities in sanidines, greyscale gradients can be used as a diffusive tracer. BSE images were processed using the ImageJ® software, in order to extract a numerical greyscale profile. In both cases, each profile was interpolated through a non-linear Boltzmann fit curve with the Mathematica® software. A few traverses done at angles smaller than 90° to the compositional boundary interface were corrected by multiplying the distance values by the sinus of the traverse angle relative to the vertical on the interface. Our preliminary</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912815C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912815C"><span>Monitoring diffuse volcanic degassing during volcanic unrests: the case of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cardellini, Carlo; Chiodini, Giovanni; Avino, Rosario; Bagnato, Emanuela; Caliro, Stefano; Frondini, Francesco; Lelli, Matteo; Rosiello, Angelo</p> <p>2017-04-01</p> <p>Hydrothermal activity at Solfatara of Pozzuoli (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Italy) results on a large area of hot soils, diffuse CO2 degassing and numerous fumaroles, releasing at the surface large amounts of gasses and thermal energy. Solfatara is one of the first sites of the world where the techniques for measuring and interpreting soil CO2 diffuse degassing were developed during 1990's and, more recently, it has become a sort of natural laboratory for testing new types of measurements of the CO2 fluxes from hydrothermal sites. The results of 30 diffuse CO2 flux surveys performed at Solfatara from 1998 to 2016 are presented and discussed. CO2 soil fluxes were measured over an area of about 1.2  1.2 km including the Solfatara crater and the hydrothermal site of Pisciarelli using the accumulation chamber technique. Each survey consisted in a number of CO2 flux measurements varying from 372 to 583 resulting in a total of 13158 measurements. This data set is one of the largest dataset ever made in the world on a single degassing volcanic-hydrothermal system. It is particularly relevant in the frame of volcanological sciences because it was acquired during a long period of unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> and because Solfatara release an amount of CO2 comparable to that released by medium-large volcanic plumes. Statistical and geostatistical elaborations of CO2 flux data allowed to characterise the sources of soil diffuse degassing, to define the extent of the area interested by the release of hydrothermal CO2 (Solfatara DDS) and to quantify the total amount of released CO2. During the last eighteen years relevant variations affected Solfatara degassing, and in particular the "background" CO2 emission , the extent of DDS and the total CO2 output, that may reflect variations in the subterraneous gas plume feeding the Solfatara and Pisciarelli emissions. In fact, the most relevant variations in Solfatara diffuse degassing well correlates with steam condensation and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4479I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4479I"><span>Triple oxygen isotope composition of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magma systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iovine, Raffaella Silvia; Wörner, Gerhard; Pack, Andreas; Sengupta, Sukanya; Carmine Mazzeo, Fabio; Arienzo, Ilenia; D'Antonio, Massimo</p> <p>2017-04-01</p> <p>Sr-O isotope relationships in igneous rocks are a powerful tool to distinguish magma sources and quantify assimilation processes in magmatic rocks. Isotopic (87Sr/86Sr and 18O/16O-17O/16O) data have been acquired on whole rocks and separated minerals (feldspar, Fe-cpx, Mg-cpx, olivine phenocrysts) from pyroclastic products of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic complex (Gulf of Naples, Southern Italy). Oxygen isotope ratios were measured by infrared laser fluorination using a Thermo MAT253 gas source isotope ratio mass spectrometer in dual inlet mode, on ˜2 mg of hand-picked phenocrysts. Variations in triple oxygen isotope ratios (17O/16O, 18O/16O) are expressed as the δ notation relative to VSMOW. Sr isotopic compositions were determined by thermal ionization mass spectrometry after standard cation-exchange methods on separated hand-picked phenocrysts (˜300 mg), and on whole rocks, in case of insufficient sample size to separate crystals. Sr-isotopes in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> minerals range from 0.707305 to 0.707605 and δ18O varies from 6.5 to 8.3‰ . Recalculated δ18Omelt values accordingly show a large range between 7.2 and 8.6‰ . Our data, compared with published δ18O-isotope data from other Italian volcanic centers (Alban Hills, Mts. Ernici, Ischia, Mt. Vesuvius, Aeolian Islands, Tuscany and Sardinia) and from subduction zones worldwide (Kamchatka, Lesser Antilles, Indonesia and Central Andean ignimbrites), show compositions that are very different from typical mantle values. Distinct trends and sources are recognized in our compilation from global data: (1) serpentinized mantle (Kamchatka), (2) sediment-enrichment in the mantle source (Indonesia, Lesser Antilles, Eolian arc), (3) assimilation of old radiogenic continental crust affecting magmas derived from sediment-modified mantle sources (Tuscany, Sardinia), (4) assimilation of lower crustal lithologies (Central Andes, Alban Hills, Mts. Ernici, Ischia). Sr-O-isotope values of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius magmas</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44..718B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44..718B"><span>Signature of magmatic processes in strainmeter records at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bagagli, M.; Montagna, C. P.; Papale, P.; Longo, A.</p> <p>2017-01-01</p> <p>Volcanic unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Southern Italy, is characterized by episodes of ground deformation, seismicity, and enhanced fumarolic activity; whether its origin is purely hydrothermal or magmatic is highly debated. We have identified ground deformation patterns in strainmeter records from a heightened unrest period in late 2006, closely resembling synthetic signals from numerical simulations of shallow magma chamber replenishment and mixing. Together with other recent findings, our results depict a situation whereby periodic arrivals of deep magma feed a shallow intrusion at 3-4 km depth. These results suggest that the analysis of strainmeter records, coupled with advanced numerical simulations of magma dynamics, could lead to new approaches in imaging subsurface dynamic processes in volcanic areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeoJI.182.1073T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeoJI.182.1073T"><span>A detailed study of the site effects in the volcanic area of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> using empirical approaches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tramelli, Anna; Galluzzo, Danilo; Del Pezzo, Edoardo; Di Vito, Mauro A.</p> <p>2010-08-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is a highly populated active <span class="hlt">caldera</span> in the south of Italy. Several hundred thousand people live within this area, which is characterized by seismicity and ground deformation episodes, known as `bradyseism'. For this reason, this area falls into a high-risk category and thus the Italian Civil Defence requires a detailed site-effect estimation. To determine the local amplification of the seismic waves for a high number of sites, we have analysed the seismic recordings of three seismic networks that have been deployed in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area over different time periods. The first network was deployed during the bradyseismic crisis of 1982-1984. We selected 22 of the highest magnitude earthquakes that were recorded during this crisis. An additional 22 seismic events were selected from those recorded by the mobile seismic network that has been in operation in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area since 2006. The third data set comprises noise recorded by 34 seismic stations that were deployed during the active SERAPIS experiment in 2001 September. The generalized inversion technique and the H/V spectral ratio method were applied to the S waves and coda waves of the earthquakes recorded by the first two seismic networks, to determine the site-transfer functions of the recording stations. The seismic noise recorded by the third network was analysed using the Nakamura's technique. The results show that the high topographical and geological heterogeneity of the sites located inside the <span class="hlt">caldera</span> has an important influence on the seismic-wave amplification. Consequently, the site-transfer functions can be different even at sites close to each other. The transfer functions of the sites located outside the <span class="hlt">caldera</span> are much more regular, apparently due to the more regular topography and geology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JVGR..254..118R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JVGR..254..118R"><span>Volcanic risk perception in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ricci, T.; Barberi, F.; Davis, M. S.; Isaia, R.; Nave, R.</p> <p>2013-03-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> which includes part of the city of Naples, is an active volcanic system; its last eruption occurred in 1538 AD. More recently two significant crises occurred between 1969 and 72 and 1982-84 and were accompanied by ground movements (bradyseism) and seismic activity, forcing people of the town of Pozzuoli to be evacuated. Since 1984 development of a volcanic emergency plan has been underway. In 2000 Civil Protection published a risk map which defined the Red Zone, an area highly at risk from pyroclastic flows, which would need to be evacuated before an eruption. The first study to evaluate the volcanic risk perceptions of the people living within the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area was completed in spring 2006, resulting in the largest sample ever studied on this topic except for one on Vesuvio area residents by Barberi et al. (2008). A 46 item questionnaire was distributed to 2000 of the approximately 300,000 residents of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Red Zone, which includes three towns and four neighborhoods within the city of Naples. A total of 1161 questionnaires were returned, for an overall response rate of 58%. Surveys were distributed to junior high and high school students, as well as to adult members of the general population. Results indicated that unlike issues such as crime, traffic, trash, and unemployment, volcanic hazards are not spontaneously mentioned as a major problem facing their community. However, when asked specific questions about volcanic risks, respondents believe that an eruption is likely and could have serious consequences for themselves and their communities and they are quite worried about the threat. Considering the events of 1969-72 and 1982-84, it was not surprising that respondents indicated earthquakes and ground deformations as more serious threats than eruptive phenomena. Of significant importance is that only 17% of the sample knows about the existence of the Emergency Plan, announced in 2001, and 65% said that they have not received</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.G31C..05T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.G31C..05T"><span>Advanced DInSAR analysis at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tiampo, K. F.; Camacho, A. G.; Fernandez, J.; Gonzalez, P. J.; Samsonov, S. V.</p> <p>2015-12-01</p> <p> at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> involve large, extended sources in a layered hydrothermal system whose location is controlled by the <span class="hlt">caldera</span> structure and stratigraphy. The temporal resolution of MSBAS approaches that of GPS daily timeseries, with superior precision and spatial resolution, making it an excellent alternative for volcano monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1513155D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1513155D"><span><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Deep Drilling Project and geothermal activities in Campania Region (Southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Natale, Giuseppe; Troise, Claudia; Troiano, Antonio; Giulia Di Giuseppe, Maria; Mormone, Angela; Carlino, Stefano; Somma, Renato; Tramelli, Anna; Vertechi, Enrico; Sangianantoni, Agata; Piochi, Monica</p> <p>2013-04-01</p> <p>The Campanian volcanic area has a huge geothermal potential (Carlino et al., 2012), similar to the Larderello-Radicondoli-Amiata region, in Tuscany (Italy), which has been the first site in the World exploited for electric production. Recently, the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Deep Drilling Project (CFDDP), sponsored by ICDP and devoted to understand and mitigate the extreme volcanic risk in the area, has also risen new interest for geothermal exploration in several areas of Italy. Following the new Italian regulations which favour and incentivise innovative pilot power plants with zero emission, several geothermal projects have started in the Campania Region, characterized by strict cooperation among large to small industries, Universities and public Research Centers. INGV department of Naples (Osservatorio Vesuviano) has the technical/scientific leadership of such initiatives. Most of such projects are coordinated in the framework of the Regional District for Energy, in which a large part is represented by geothermal resource. Leading geothermal projects in the area include 'FORIO' pilot plant project, aimed to build two small (5 MWe each one) power plants in the Ischia island and two projects aimed to build pilot power plants in the Agnano-Fuorigrotta area in the city of Naples, at the easternmost part of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. One of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> projects, 'SCARFOGLIO', is aimed to build a 5 MWe geothermal power plant in the Agnano area, whereas the 'START' project has the goal to build a tri-generation power plant in the Fuorigrotta area, fed mainly by geothermal source improved by solar termodynamic and bio-mass. Meanwhile such projects enter the field work operational phase, the pilot hole drilling of the CFDDP project, recently completed, represents an important experience for several operational aspects, which should contitute an example to be followed by the next geothermal activities in the area. It has been furthermore a source of valuable data for geothermal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9864C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9864C"><span>Automatic procedure for quasi-real time seismic data processing at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Capuano, Paolo; Ciaramella, Angelo; De Lauro, Enza; De Martino, Salvatore; Falanga, Mariarosaria; Petrosino, Simona</p> <p>2014-05-01</p> <p>The accuracy of automatic procedures for detecting seismic events and locating their sources is influenced by several factors such as errors in picking seismic phases often buried in the high-level ambient noise, network geometry and modelling errors. fundamental objective is the improvement of these procedures by developing accurate algorithms for quasi-real time seismic data processing, easily managed in observatory practice. Recently a robust automatic procedure has been implemented for detecting, onset picking and identifying signal phases in continuous seismic signal with an application at the seismicity recorded at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> (Italy) during the 2006 ground uplift (Ciaramella et al. 2011). An Independent Component Analysis based approach for the Blind Source Separation of convolutive mixtures (CICA) has been adopted to obtain a clear separation of low-energy Long Period events (LPs) from the high-level ambient noise allowing to compile a complete seismic catalogue and better quantify the seismic energy release. In this work, we apply CICA at the seismic signal continuously recorded during the entire 2006 at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. First, we have performed tests on synthetic data in order to improve the reliability and the accuracy of the procedure. The performance test using very noisy synthetic data shows that the method works even in case of very poor quality data characterized by very low signal to noise ratio (SNR). Second, we have improved CICA automatic procedure recovering the information on the amplitudes of the extracted independent components. This is crucial for further analysis, starting from a prompt estimate of magnitude/energy of the highlighted events. Data used for the present analysis were collected by four broadband three-component seismic stations (ASB2, AMS2, TAGG, BGNG) belonging to the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> seismic monitoring network, managed by the 'Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Vesuviano (INGV-OV)' (see for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SolE....5...25H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SolE....5...25H"><span>The permeability and elastic moduli of tuff from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy: implications for ground deformation modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heap, M. J.; Baud, P.; Meredith, P. G.; Vinciguerra, S.; Reuschlé, T.</p> <p>2014-01-01</p> <p>The accuracy of ground deformation modelling at active volcanoes is a principal requirement in volcanic hazard mitigation. However, the reliability of such models relies on the accuracy of the rock physical property (permeability and elastic moduli) input parameters. Unfortunately, laboratory-derived values on representative rocks are usually rare. To this end we have performed a systematic laboratory study on the influence of pressure and temperature on the permeability and elastic moduli of samples from the two most widespread lithified pyroclastic deposits at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic district, Italy. Our data show that the water permeability of Neapolitan Yellow Tuff and a tuff from the Campanian Ignimbrite differ by about 1.5 orders of magnitude. As pressure (depth) increases beyond the critical point for inelastic pore collapse (at an effective pressure of 10-15 MPa, or a depth of about 750 m), permeability and porosity decrease significantly, and ultrasonic wave velocities and dynamic elastic moduli increase significantly. Increasing the thermal stressing temperature increases the permeability and decreases the ultrasonic wave velocities and dynamic elastic moduli of the Neapolitan Yellow Tuff; whereas the tuff from the Campanian Ignimbrite remains unaffected. This difference is due to the presence of thermally unstable zeolites within the Neapolitan Yellow Tuff. For both rocks we also find, under the same pressure conditions, that the dynamic (calculated from ultrasonic wave velocities) and static (calculated from triaxial stress-strain data) elastic moduli differ significantly. The choice of elastic moduli in ground deformation modelling is therefore an important consideration. While we urge that these new laboratory data should be considered in routine ground deformation modelling, we highlight the challenges for ground deformation modelling based on the heterogeneous nature (vertically and laterally) of the rocks that comprise the <span class="hlt">caldera</span> at <span class="hlt">Campi</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ESASP.697E..28M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ESASP.697E..28M"><span>High Resolution Monitoring Of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Naples, Italy) By Exploiting TerraSAR-X Data: An Application Of Solifatara Crater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minet, Christian; Goel, Kanika; Aquino, Ida; Avino, Rosario; Berrino, Giovanna; Caliro, Stefano; Chidini, Giovanni; De Martino, Prospero; Del Gaudio, Carlo; Ricco, Ciro; Siniscalchi, Valeria; Borgsrtom, Sven</p> <p>2012-01-01</p> <p>Geodetic monitoring of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, west of Naples (Italy), is carried out through integrated ground based networks and space-borne Differential InSAR (DInSAR) techniques, exploiting the SAR sensors onboard ERS1-2 (till the end of their lifetime) and ENVISAT satellites. Unfortunately, C-band sensors give no information when dealing with very low deformation rates and very small deforming areas. To overcome these problems, we decided to use TerraSAR-X from DLR, a high resolution SAR sensor operating in the X-band, starting in December 2009. TerraSAR-X Spotlight scenes covering the main part of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> and centred on the Solfatara crater were used for a DInSAR analysis, using DLR’s InSAR software. Starting from this period, many field surveys highlighted a strong fumarolic activity in the Solfatara - Pisciarelli area [1], so geodetic and geochemical observations were strongly increased. Furthermore, the growing stack of High-Resolution Spotlight TerraSAR-X data processed using the Small Baseline Subset Algorithm (SBAS) as described by Berardino at al. [2], allowed getting information for a bigger area and data from ground based networks could be integrated. First results of the SBAS processing and the combination of different observation techniques are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1410553P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1410553P"><span>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>-hosted high-temperature and high-saline geothermal system in the Southern Italy: the implication of the geothermal resource as derived by the present state of the knowledge through 70 years of volcanological, structural, petrolog</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piochi, M.; Di Vito, M. A.; Mormone, A.; De Natale, G.; Tramelli, A.; Troise, C.; Carlino, S.</p> <p>2012-04-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy) hosts a geothermal system characterized by: i) high thermal gradient (temperature up to 420°C at 3050 m b.s.l.), ii) high temperature (up to ~90-150°C at very shallow depth) fumaroles, iii) multiple meteoric to brine (TDS up to 33 g•l-1; temperature up to 95 °C) aquifers and iv) at least 1500 tonnes per day of CO2 emissions. This area is highly urbanized despite the repeated occurrence of ground deformation phenomena accompanied by seismicity with volcano-tectonic and long-period micro-earthquakes. The <span class="hlt">caldera</span> has been widely studied by geologist and geophysicists. In particular, since '40s, the <span class="hlt">caldera</span> has drawn scientific interest for its geothermal capability inducing the companies AGIP (Azienda Geologica Italiana Petroli) and SAFEN (Società Anonima Forze Endogene Napoletane) to drill more than one hundred 80-to-3100 m deep wells. However this experience did not reach the exploitation phase due to technological and communication problems. The geothermal potential (thermal and electric) is evaluated of about 6 GWy. The recent <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Deep Drilling Project [De Natale and Troise, 2011], sponsored by the International Continental Scientific Drilling Program, foresees the realization of medium-to-deep wells in the <span class="hlt">caldera</span> with the ambition of stimulating interest in geothermal energy exploitation and technology development and, in addition of installing downhole monitoring systems. The geological knowledge of the area is the benchmark for the drilling sites selection. We reconstructed a multi-disciplinary conceptual model updated on the basis of the most recent scientific results and findings. In particular, the constrains (the most important are listed in brackets) comes from: i) boreholes (litho-stratigraphy, aquifer location, depth-related temperature), ii) fieldwork (stratigraphy, location of structural fractures and eruption vents), iii) petrology and melt inclusions (pressure and temperature of magma with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1877D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1877D"><span>4D imaging of the seism-geochemical dynamics leading to recent <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Chiodini, Giovanni; Vilardo, Giuseppe; Del Pezzo, Edoardo; Castellano, Mario; Colombelli, Simona; Tisato, Nicola; Ventura, Guido</p> <p>2017-04-01</p> <p>Understanding what produced historical unrests at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> super volcanic <span class="hlt">caldera</span> is key to forecasting eruptions at the volcano in the near future. Here, we present a novel seismic attenuation and 4D lapse-time source model spanning the years 1983-84 and working in parallel with geochemical data and physical simulations. Results reveal a 4-5 km deep, NNW-SSE striking hot zone, either a magma sill or fluid reservoir, offshore the city of Pozzuoli, feeding a reservoir of supercritical fluids/foams topping at a depth of about 3 km. Repeated injections of hot materials from depth in September-October 1983 into the reservoir produce a second fluid phase accumulating under a rock-physics derived caprock, enhancing subsidence. The release of this additional stress after the breaking of the reservoir, on April 1st 1984, leads to the opening of a western, morphologically-defined path, connecting the centre of the <span class="hlt">caldera</span> with the site of its last eruption (1538 AD). The hot zone offshore Pozzuoli is the deepest source of seismic activity, ground deformation, and vertical/lateral fluid migration inducing subsidence detected at the volcano during its major monitored unrest (1983-84). Still active today and related to its last historical eruption, it thus controls unrest and eruptive behaviour of the area of highest volcanic hazard in continental Europe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28754925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28754925"><span>Monitoring diffuse volcanic degassing during volcanic unrests: the case of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cardellini, C; Chiodini, G; Frondini, F; Avino, R; Bagnato, E; Caliro, S; Lelli, M; Rosiello, A</p> <p>2017-07-28</p> <p>In volcanoes with active hydrothermal systems, diffuse CO2 degassing may constitute the primary mode of volcanic degassing. The monitoring of CO2 emissions can provide important clues in understanding the evolution of volcanic activity especially at <span class="hlt">calderas</span> where the interpretation of unrest signals is often complex. Here, we report eighteen years of CO2 fluxes from the soil at Solfatara of Pozzuoli, located in the restless <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. The entire dataset, one of the largest of diffuse CO2 degassing ever produced, is made available for the scientific community. We show that, from 2003 to 2016, the area releasing deep-sourced CO2 tripled its extent. This expansion was accompanied by an increase of the background CO2 flux, over most of the surveyed area (1.4 km(2)), with increased contributions from non-biogenic source. Concurrently, the amount of diffusively released CO2 increased up to values typical of persistently degassing active volcanoes (up to 3000 t d(-1)). These variations are consistent with the increase in the flux of magmatic fluids injected into the hydrothermal system, which cause pressure increase and, in turn, condensation within the vapor plume feeding the Solfatara emission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1374327','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1374327"><span>The thermal regime of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magmatic system reconstructed through 3D numerical simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Di Renzo, Valeria; Wohletz, Kenneth; Civetta, Lucia; Moretti, Roberto; Orsi, Giovanni; Gasparini, Paolo</p> <p>2016-11-11</p> <p>In this paper, we illustrate a quantitative conductive/convective thermal model incorporating a wide range of geophysical, petrological, geological, geochemical and isotopical observations that constrain the thermal evolution and present state of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc) magmatic system. The proposed model has been computed on the basis of the current knowledge of: (1) the volcanic and magmatic history of the volcano over the last 44 ka, (2) its underlying crustal structure, and (3) the physical properties of the erupted magmas. 3D numerical simulations of heat conduction and convection within heterogeneous rock/magma materials with evolving heat sources and boundary conditions that simulate magma rise from a deep (≥ 8 km depth) to shallow (2–6 km) reservoirs, magma chamber formation, magma extrusion, <span class="hlt">caldera</span> collapse, and intra-<span class="hlt">caldera</span> hydrothermal convection, have been carried out. The evolution of the CFc magmatic system through time has been simulated through different steps related to its changes in terms of depth, location and size of magma reservoirs and their replenishment. The thermal modeling results show that both heat conduction and convection have played an important role in the CFc thermal evolution, although with different timing. Finally, the simulated present heat distribution is in agreement with the measured geothermal profiles (Agip, 1987), reproduces the thermal gradient peaks at the CFc margins in correspondence to the anomalies in surface gradients (Corrado et al., 1998), and suggests temperatures of 700 °C at depth of 4 km in the central portion of the <span class="hlt">caldera</span>, in agreement with the estimated temperature for the brittle-ductile transition (Hill, 1992).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1374327-thermal-regime-campi-flegrei-magmatic-system-reconstructed-through-numerical-simulations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1374327-thermal-regime-campi-flegrei-magmatic-system-reconstructed-through-numerical-simulations"><span>The thermal regime of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magmatic system reconstructed through 3D numerical simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Di Renzo, Valeria; Wohletz, Kenneth; Civetta, Lucia; ...</p> <p>2016-11-11</p> <p>In this paper, we illustrate a quantitative conductive/convective thermal model incorporating a wide range of geophysical, petrological, geological, geochemical and isotopical observations that constrain the thermal evolution and present state of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc) magmatic system. The proposed model has been computed on the basis of the current knowledge of: (1) the volcanic and magmatic history of the volcano over the last 44 ka, (2) its underlying crustal structure, and (3) the physical properties of the erupted magmas. 3D numerical simulations of heat conduction and convection within heterogeneous rock/magma materials with evolving heat sources and boundary conditions thatmore » simulate magma rise from a deep (≥ 8 km depth) to shallow (2–6 km) reservoirs, magma chamber formation, magma extrusion, <span class="hlt">caldera</span> collapse, and intra-<span class="hlt">caldera</span> hydrothermal convection, have been carried out. The evolution of the CFc magmatic system through time has been simulated through different steps related to its changes in terms of depth, location and size of magma reservoirs and their replenishment. The thermal modeling results show that both heat conduction and convection have played an important role in the CFc thermal evolution, although with different timing. Finally, the simulated present heat distribution is in agreement with the measured geothermal profiles (Agip, 1987), reproduces the thermal gradient peaks at the CFc margins in correspondence to the anomalies in surface gradients (Corrado et al., 1998), and suggests temperatures of 700 °C at depth of 4 km in the central portion of the <span class="hlt">caldera</span>, in agreement with the estimated temperature for the brittle-ductile transition (Hill, 1992).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..328..210D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..328..210D"><span>The thermal regime of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magmatic system reconstructed through 3D numerical simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Renzo, Valeria; Wohletz, Kenneth; Civetta, Lucia; Moretti, Roberto; Orsi, Giovanni; Gasparini, Paolo</p> <p>2016-12-01</p> <p>We illustrate a quantitative conductive/convective thermal model incorporating a wide range of geophysical, petrological, geological, geochemical and isotopical observations that constrain the thermal evolution and present state of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc) magmatic system. The proposed model has been computed on the basis of the current knowledge of: (1) the volcanic and magmatic history of the volcano over the last 44 ka, (2) its underlying crustal structure, and (3) the physical properties of the erupted magmas. 3D numerical simulations of heat conduction and convection within heterogeneous rock/magma materials with evolving heat sources and boundary conditions that simulate magma rise from a deep (≥ 8 km depth) to shallow (2-6 km) reservoirs, magma chamber formation, magma extrusion, <span class="hlt">caldera</span> collapse, and intra-<span class="hlt">caldera</span> hydrothermal convection, have been carried out. The evolution of the CFc magmatic system through time has been simulated through different steps related to its changes in terms of depth, location and size of magma reservoirs and their replenishment. The thermal modeling results show that both heat conduction and convection have played an important role in the CFc thermal evolution, although with different timing. The simulated present heat distribution is in agreement with the measured geothermal profiles (Agip, 1987), reproduces the thermal gradient peaks at the CFc margins in correspondence to the anomalies in surface gradients (Corrado et al., 1998), and suggests temperatures of 700 °C at depth of 4 km in the central portion of the <span class="hlt">caldera</span>, in agreement with the estimated temperature for the brittle-ductile transition (Hill, 1992).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3126V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3126V"><span>The Rock Physics of Fiber-Reinforced Rocks Helps Explain Uplifts at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Volcano-Hydrothermal System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vanorio, T.; Kanitpanyacharoen, W.</p> <p>2015-12-01</p> <p>The <span class="hlt">caldera</span> of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is one of the active volcano-hydrothermal systems of the Mediterranean region experiencing notable unrest episodes in a densely populated area. One peculiar trait characterizes the unrest of this system: the ability of withstanding large uplifts before setting off a swarm of microeartquakes. Therefore, one core question is how the subsurface rocks of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> withstand such a large strain and have high strength. The rock physics analysis of well cores up to 3 km provides evidence for the existence of two horizons, above and below the seismogenic area, underlying a natural, coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The impermeable caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix made of intertwining filaments of ettringite and tobemorite, resulting from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that of the engineering of the Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. The importance of these findings lies not only on the fibrous and compositionally nature of the caprock but also on its possible physicochemical deterioration. Given the P-T-XCO2 conditions regulating the decarbonation reactions, possible influx of new brine into the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> system dilutes the existing CO2, thus triggering further decarbonation reaction. This leads to the formation of additional CO2, methane, and steam. As these gases rise toward the surface, they are halted by the natural concrete-like layer, which would lead to pore pressure increase and subsequent ground deformations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1617010P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1617010P"><span>Permeability of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magmas: examples from the Campanian Ignimbrite and Monte Nuovo eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Polacci, Margherita; Bouvet de Maisonneuve, Caroline; Giordano, Daniele; Piochi, Monica; Mancini, Lucia; Degruyter, Wim; Bachmann, Olivier</p> <p>2014-05-01</p> <p>We performed permeability measurements on trachy-phonolitic pyroclastic products from the Campanian Ignimbrite and Monte Nuovo, two explosive eruptions from the active <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Southern Italy. Viscous (Darcian) permeability spans a wide range between 1.22x10-14 and 9.31x10-11 m2. Inertial (non-Darcian) permeability follows the same trend as viscous permeability: it increases as viscous permeability increases, highlighting the strong direct correlation between these two parameters. We observe that vesicularity does not exert a first order control on permeability: the Monte Nuovo scoria clasts are the most permeable samples but not the most vesicular; pumice clasts from the Campanian Ignimbrite proximal facies, whose vesicularity is comparable with that of Monte Nuovo scoriae, are instead the least permeable. In addition, we find that sample geometry exhibits permeability anisotropy as samples oriented parallel to vesicle elongation are more permeable than those oriented perpendicular. We compare our results with permeability values of volcanic products from effusive and explosive activity, and discuss the role of melt viscosity and crystallinity on magma permeability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813463W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813463W"><span>Sr-O isotope systematics in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magma systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wörner, Gerhard; Iovine, Raffaella; Carmine Mazzeo, Fabio; D'Antonio, Massimo; Arienzo, Ilenia; Civetta, Lucia; Orsi, Giovanni</p> <p>2016-04-01</p> <p> a large range mostly between 7 and 10 ‰ VSMOW, maximum and minimum values reach from ~11 to ~6 ‰ VSMOW. Our data obtained so far show compositions that are very different from typical mantle values and that span a very large range towards heavy δ18O values compared to other magmatic compositions from the Italian Peninsula. We compare our clinopyroxene and olivine data with published clinopyroxene and olivine O-isotope data from other Italian volcanic centers (Alban Hills, Mts. Ernici, Ischia, Mt. Vesuvius, Aeolian Islands, Tuscany and Sardinia) and from subduction zones worldwide (Kamchatka, Lesser Antilles, Indonesia and Central Andean ignimbrites). Distinct trends and sources are recognized: (1) serpentinized mantle (Kamchatka), (2) sediment-enrichment in the mantle source (Indonesia, Vesuvius), (3) magma assimilation by old radiogenic continental crust (Alban Hills, Tuscany, Ischia), (4) assimilation by mafic crust (Andes). Sr-O-isotope values of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius magmas fall on the same vertical trend in Sr-O isotope space that deviates profoundly from all other subduction-related magmas. This indicates that magmas are derived from (a) a mantle source variably modified by pelagic sediments (as for Vesuvius) that were later (b) assimilated by highly δ18O-enriched crustal material that did not further significantly affect the Sr-isotope composition. From Sr-O isotope relations, this crustal signal could be introduced through interaction with Mesozoic limestone and/or low-T altered volcanic material from previous volcanic activity in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030583','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030583"><span>The Breccia Museo formation, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, southern Italy: Geochronology, chemostratigraphy and relationship with the Campanian Ignimbrite eruption</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fedele, L.; Scarpati, C.; Lanphere, M.; Melluso, L.; Morra, V.; Perrotta, A.; Ricci, G.</p> <p>2008-01-01</p> <p>The Breccia Museo is one of the most debated volcanic formations of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic district. The deposit, made up of six distinctive stratigraphic units, has been interpreted by some as the proximal facies of the major <span class="hlt">caldera</span>-forming Campanian Ignimbrite eruption, and by others as the product of several, more recent, independent and localized events. New geochemical and chemostratigraphical data and Ar - Ar age determinations for several units of the Breccia Museo deposits (???39 ka), correlate well with the Campanian Ignimbrite-forming eruption. The chemical zoning of the Breccia Museo deposits is interpreted here to be a consequence of a three-stage event that tapped a vertically zoned trachytic magma chamber. ?? Springer-Verlag 2008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008BVol...70.1189F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008BVol...70.1189F"><span>The Breccia Museo formation, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, southern Italy: geochronology, chemostratigraphy and relationship with the Campanian Ignimbrite eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedele, Lorenzo; Scarpati, Claudio; Lanphere, Marvin; Melluso, Leone; Morra, Vincenzo; Perrotta, Annamaria; Ricci, Gennaro</p> <p>2008-10-01</p> <p>The Breccia Museo is one of the most debated volcanic formations of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic district. The deposit, made up of six distinctive stratigraphic units, has been interpreted by some as the proximal facies of the major <span class="hlt">caldera</span>-forming Campanian Ignimbrite eruption, and by others as the product of several, more recent, independent and localized events. New geochemical and chemostratigraphical data and Ar-Ar age determinations for several units of the Breccia Museo deposits (~39 ka), correlate well with the Campanian Ignimbrite-forming eruption. The chemical zoning of the Breccia Museo deposits is interpreted here to be a consequence of a three-stage event that tapped a vertically zoned trachytic magma chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....12216A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....12216A"><span>Migration of the data from the active seismic experiment Serapis in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic field (southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Auger, E.; Zollo, A.; Judenherc, S.; Satriano, C.</p> <p>2003-04-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is located 15 km west of the city of Naples (southern Italy), and has experienced in 1970-72 and 1982-84 two relevant ground uplift phenomena accompanied by an intense microseismic activity. Its structural features are still debated, as, in particular, the possible depth of the carbonatic basement beneath the <span class="hlt">caldera</span>, the shape of the buried <span class="hlt">caldera</span> rim at sea, the location and geometry of the magmatic feeding system. An active seismic experiment (Serapis) was carried out on September, 2001 to investigate these questions. 5000 airgun shots were performed at sea by the Nadir vessel, a boat operated by the french oceanographic institute Ifremer. 80 OBS were deployed at the sea bottom and 84 stations on land . The sensors were laid out so as to have a dense data mesh at the <span class="hlt">caldera</span>'s center (one OBS every km), and some long distance profiles with one OBS every 5 km. The shot spacing was 125 m. The preliminary analysis shows high quality data, with clear evidence and lateral consistency of reflected arrivals. The migration technique is applied to image the seismic discontinuities in the medium, such as interfaces and diffracting bodies. This poster reminds the methodological principles,and presents the results of the application.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.252..160M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.252..160M"><span>Trace element partitioning between clinopyroxene and trachy-phonolitic melts: A case study from the Campanian Ignimbrite (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mollo, S.; Forni, F.; Bachmann, O.; Blundy, J. D.; De Astis, G.; Scarlato, P.</p> <p>2016-05-01</p> <p>The partitioning of trace elements between crystals and melts provides an important petrogenetic tool for understanding magmatic processes. We present trace element partition coefficients measured between clinopyroxene phenocrysts and trachy-phonolitic magmas at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy), whose late Quaternary volcanism has been characterized by two major <span class="hlt">caldera</span>-forming events (Campanian Ignimbrite at ~ 39 ka, and Neapolitan Yellow Tuff at ~ 15 ka). Our data indicate that the increase of trivalent rare earth elements and yttrium into the crystal lattice M2 site is facilitated by the charge-balancing substitution of Si4 + with Al3 + on the tetrahedral site. Higher concentrations of tetravalent and pentavalent high field strength elements on the M1 site are also measured when the average charge on this site is increased by the substitution of divalent cations by Alvi. In contrast, due to these charge balance requirements, divalent transitional elements become less compatible within the crystal lattice. On the basis of the lattice strain theory, we document that the incorporation of rare earth elements and yttrium in clinopyroxene is influenced by both compositional and physical parameters. Data from this study allow to update existing partitioning equations for rare earth elements in order to construct a self-consistent model for trachy-phonolitic magmas based on the lattice strain theory. The application of this model to natural products from the Campanian Ignimbrite, the largest <span class="hlt">caldera</span>-forming eruption at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, reveals that the complex rare earth element pattern recorded by the eruptive products can be successfully described by the stepwise fractional crystallization of clinopyroxene and feldspar where the clinopyroxene-melt partition coefficient changes progressively as a function of the physicochemical conditions of the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.4194D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.4194D"><span>Chemostratigraphy of Products of The Astroni Activity (4.1-3.8 Ka, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>D'Antonio, M.; Isaia, R.; Bolognesi, L.; Civetta, L.; di Vito, M. A.; Orsi, G.; Tonarini, S.</p> <p></p> <p>The Astroni volcano is a well-preserved tuff-ring in the NE sector of the Neapolitan Yellow Tuff (NYT, 12 ka BP) <span class="hlt">caldera</span>, the youngest of the two major collapses which generated the nested <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (CFc). The volcano has been characterised by a long-lasting activity in the age range 4.1-3.8 ka BP, generating 7 pyroclastic and 2 lava units. Thus the whole rock sequence is subdivided in Units named 1 through 9 upsection. Detailed petrographical, geochemical and isotopic investigations have been carried out on these rocks (pumice and scoria fragments, lavas) which have tex- tures variable from sub-aphyric to highly porphyritic to glomeroporphyritic. The phe- nocrysts are plagioclase, alkali-feldspar, Mg- to Fe-rich zoned clinopyroxene, biotite, opaques and apatite, in order of decreasing abundance. Their abundance is variable along the sequence: lower in Units 1 to 4, higher in Units 5 to 9. The groundmass ranges from hypocrystalline to hyalopilitic in pumice and scoria fragments, to felty in the lavas. The analysed rocks are nepheline normative trachyte to alkali-trachyte. Whole-rock major and trace element contents vary regularly with D.I. (71.5 and 81.0), suggesting fractional crystallization of mineral phases in a magma evolving from tra- chyte to alkali-trachyte. However, whole-rock 87Sr/86Sr values range from 0.70725 to 0.70755. It is noteworthy that the extreme detected values match those of the prod- ucts of the largest <span class="hlt">caldera</span>-forming eruptions: the Campanian Ignimbrite (37 ka) and NYT, respectively. The 87Sr/86Sr ratio is variable with the chemical composition of the products, suggesting open-system evolution process acting in the magma reser- voir feeding the Astroni volcano. Furthermore, the chemostratigraphy of the Astroni sequence shows that activity started with extrusion of more evolved, alkali-trachytic magma (DI about 80-81; 87Sr/86Sr = 0.70755), becoming progressively less differ- entiated and less radiogenic up to emplacement of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.205.1813S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.205.1813S"><span>A strongly heterogeneous hydrothermal area imaged by surface waves: the case of Solfatara, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Serra, Marcello; Festa, Gaetano; Roux, Philippe; Gresse, Marceau; Vandemeulebrouck, Jean; Zollo, Aldo</p> <p>2016-06-01</p> <p>We investigated the shallow structure of the Solfatara, a volcano within the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, southern Italy, using surface waves as a diagnostic tool. We analysed data collected during the RICEN campaign, where a 3-D active seismic experiment was performed on a dense regular grid of 90 m × 115 m using a Vibroseis as the seismic source. After removal of the source time function, we analysed the surface wave contribution to the Green's function. Here, a 1-D approximation can hold for subgrids of 40 m × 40 m. Moreover, we stacked all of the signals in the subgrid according to source-receiver distance bins, despite the absolute location of the source and the receiver, to reduce the small-scale variability in the data. We then analysed the resulting seismic sections in narrow frequency bands between 7 and 25 Hz. We obtained phase and group velocities from a grid search, and a cost function based on the spatial coherence of both the waveforms and their envelopes. We finally jointly inverted the dispersion curves of the phase and group velocities to retrieve a 1-D S-wave model local to the subgrid. Together, the models provided a 3-D description of the S-wave model in the area. We found that the maximum penetration depth is 15 m. In the first 4 m, we can associate the changes in the S-wave field to the temperature gradient, while at greater depths, the seismic images correlate with the resistivity maps, which indicate the water layer close to the Fangaia area and an abrupt variation moving towards the northeast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1213960P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1213960P"><span>The extimated presence of differentiated higly explosive magmas beneath Vesuvius and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>: evidence from geochemical and textural studies.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pappalardo, Lucia; Mastrolorenzo, Giuseppe</p> <p>2010-05-01</p> <p>Highly catastrophic explosive eruptions are supplied by Si-rich magmas, generated at shallower level in crust by the evolution of mantle liquids. The timescale of these evolution processes is a crucial factor, because of its control on the length of volcano repose interval leading to high explosive events. <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Somma-Vesuvius alkaline volcanic systems, located respectively at few kilometers west and east of Neapolitan metropolitan area, produced a variety of eruptions ranging from not explosive lava flows and domes to highly destructive eruptions. Both these high risk volcanoes are in repose time since the last eruption occurred in the 1538 and 1944 BP, respectively. Since that time, the volcanoes experienced fumarolic activity, low level of seismicity with rare earthquakes swarms, as well as two bradyseismic crisis (1969-1972 and 1982-1984) localized in the center of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, that generated a net uplift of 3.5 m around the town of Pozzuoli. A wide low velocity layer interpreted as an extended magmatic body has been detected at 8-10 km depth beneath these volcanoes by seismic data. The capability of this reservoir to erupt explosively again strongly depends on magma differentiation degree, therefore the knowledge of the time lapse necessary at not explosive mafic liquids to differentiate toward explosive magmas is very crucial to predict the size of a possible short-term future eruption in Campanian area. Our petrologic data indicate that a multi-depth supply system was active under the Campanian Plain since 39 ka. Fractional crystallization during magma cooling associated with upward migration of less dense evolved liquids appears to be the prevalent differentiation process. Our results indicate that huge steam exolution occurred during the late stage of trachyte and phonolite crystallization thus accounting for the high Volcanic Explosivity Index (VEI) of eruptions supplied by these melts. Moreover our CSD data on phenocrysts reveal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917156B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917156B"><span>The Vesuvius/<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Supersite: state of the art and future perspectives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borgstrom, Sven; Del Gaudio, Carlo; De Martino, Prospero; Prats-Iraola, Pau; Nannini, Matteo; Vecchioli, Francesco; Minati, Federico; Costantini, Mario; Stramondo, Salvatore; Bignami, Christian; Polcari, Marco; Fabrizia Buongiorno, Maria; Silvestri, Malvina; Pepe, Antonio; Pepe, Susi; Solaro, Giuseppe; Tizzani, Pietro; Siniscalchi, Valeria</p> <p>2017-04-01</p> <p>The Vesuvius/<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Supersite was established in April, 2014 with the aim of improving monitoring and knowledge of one of the areas with the highest volcanic risk worldwide, due to the strong urbanization of the city of Naples and surroundings, lying between two active volcanoes: Vesuvius on the east and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> on the west, this latter with a recorded uplift of about 35 centimeters from 2011 to date. Such deformation suggested to the Italian Civil Protection Department (ICPD) to move from the base (green) alert level to attention (yellow) level in the framework of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> National Emergency Plan. In the first 2014-2016 biennial period, relevant results were carried out by the Supersite Science Team, apart from the outcomes of the ESA-SEOM INSARAP (Sentinel-1 INSAR Performance Study with TOPS data) project. Results are mainly focused on InSAR (S1-A, CSK, TSX) data processing, exploiting both SBAS and PS Interferometry over the Neapolitan volcanoes, with generation of ground deformation time series and comparison between LOS/inverted (E-W, vertical) InSAR and geodetic data, these latter from the INGV-Osservatorio Vesuviano monitoring networks. After the first biennial period, a detailed report on the Supersite activities has been submitted and approved by CEOS for satellite data provision for the next 2016-2018 period. Besides the continuation of the work in progress, future steps will consist in a detailed InSAR study of Vesuvius, mainly in the upper coherent part of the volcano, in order to characterize the area of interest from the engineering geology point of view. Moreover, DLR is planning an airborne campaign with their F-SAR sensor over <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>; the contribution from INGV-OV to this campaign will consist in validating InSAR measurements with continuous GPS (cGPS) data. The campaign will take place around May and then again in 2018. With regard to the societal benefits of the current activities of the Supersite, the main</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.449..259F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.449..259F"><span>The origin of a zoned ignimbrite: Insights into the Campanian Ignimbrite magma chamber (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Forni, Francesca; Bachmann, Olivier; Mollo, Silvio; De Astis, Gianfilippo; Gelman, Sarah E.; Ellis, Ben S.</p> <p>2016-09-01</p> <p><span class="hlt">Caldera</span>-forming eruptions, during which large volumes of magma are explosively evacuated into the atmosphere from shallow crustal reservoirs, are one of the most hazardous natural events on Earth. The Campanian Ignimbrite (CI; <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy) represents a classical example of such events, producing a voluminous pyroclastic sequence of trachytic to phonolitic magma that covered several thousands of squared kilometers in the south-central Italy around 39 ka ago. The CI deposits are known for their remarkable geochemical gradients, attributed to eruption from a vertically zoned magma chamber. We investigate the relationships between such chemical zoning and the crystallinity variations observed within the CI pyroclastic sequence by combining bulk-rock data with detailed analyses of crystals and matrix glass from well-characterized stratigraphic units. Using geothermometers and hygrometers specifically calibrated for alkaline magmas, we reconstruct the reservoir storage conditions, revealing the presence of gradients in temperature and magma water content. In particular, we observe a decrease in crystallinity and temperature and an increase in magma evolution and water content from the bottom to the top of the magma chamber. We interpret these features as the result of protracted fractional crystallization leading to the formation of a cumulate crystal mush at the base of the eruptible reservoir, from which highly evolved, crystal-poor, water-rich and relatively cold melts were separated. The extracted melts, forming a buoyant, easily eruptible cap at the top of the magma chamber, fed the initial phases of the eruption, until <span class="hlt">caldera</span> collapse and eruption of the deeper more crystalline part of the system. This late-erupted, crystal-rich material represents remobilized portions of the cumulate crystal mush, partly melted following hotter recharge. Our interpretation is supported by: 1) the positive bulk-rock Eu anomalies and the high Ba and Sr contents observed in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813456F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813456F"><span>The origin of a zoned ignimbrite: insights into the Campanian Ignimbrite magma chamber (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Forni, Francesca; Bachmann, Olivier; Mollo, Silvio; De Astis, Gianfilippo</p> <p>2016-04-01</p> <p>The Campanian Ignimbrite (CI; <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy), dated at 39 ka, is a widespread pyroclastic sequence emplaced during a cataclysmic <span class="hlt">caldera</span>-forming eruption fed by trachytic to phonolitic magmas. The CI pyroclastic sequence is famous for its remarkable geochemical gradients,attributed to the presence of a vertically zoned magma chamber. Combining bulk-rock data with detailed phenocrysts and matrix glass analyses from well characterized stratigraphic units, we investigate the relatioships between such chemical zoning and the crystallinity variations observed along the CI pyroclastic sequence. Using geothermometers and hygrometers specifically calibrated for alkaline magmas, we reconstruct the reservoir storage conditions, revealing the presence of gradients in temperature and magma water content. In particular, we observe an increase in crystallinity and temperature and a decrease in magma evolution and water content from the bottom to the top of the sequence. We interpret these features as the result of protracted fractional crystallization leading to the formation of a cumulate crystal mush at the base of the eruptible reservoir, from which highly evolved, crystal-poor, water-rich and relatively cold melts were separated. The extracted melts, forming a buoyant, easily eruptible cap at the top of the magma chamber, fed the initial phases of the eruption, until <span class="hlt">caldera</span> collapse and eruption of the deeper, more crystalline part of the system. This late-erupted, crystal-rich material, represents remobilized portions of the cumulate crystal mush, rejuvenated after mafic recharge. Our interpretation is supported by: 1) the bulk-rock positive Eu anomalies and the high Ba and Sr contents observed in the crystal-rich units, implying feldspar accumulation; 2) the positive Eu anomalies in the matrix glass of the crystal-rich units, testifying to the presence of liquid derived from partial melting of low temperature mineral phases within the crystal mush (feldspars and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T41B2125H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T41B2125H"><span>The physical and chemical properties of tuffs from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy): the influence of thermal and stress-induced microcracking</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heap, M. J.; Laumann, A.; Hess, K.; Lavallee, Y.; Dingwell, D. B.; Meredith, P. G.; Orsi, G.</p> <p>2010-12-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy), 6km in diameter, poses great threat to densely-populated region in and surrounding Naples. Uplift, a result of the intrusion of magma, has been systematically recorded since the nineteenth century and indicates three major episodes of uplift, the latter of which continues to this day. Studies have postulated that this uplift is expected to continue for another 80-90 years and possibly increasing the likelihood of eruption. The majority of erupted material at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is in the form of tuff. However, only recently have studies started to investigate how fundamental physical properties of tuff can alter with depth and temperature. Such properties may not only unravel key information on fluid and gas flow as well as seismic activity within the <span class="hlt">caldera</span>, but they are essential parameters for ground deformation modelling and tomography used to monitor magma movement at depth. Here we present a comprehensive experimental dataset on how both the physical and chemical properties of three representative tuffs from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> change with increasing heat-treatment temperature (up to 1000oC). The tuffs are the grey Campanian Ignimbrite (CI), Neapolitan Yellow Tuff (NYT) and Piperno Tuff (PT). Thermal cracking analysis, using a fast-acquisition acoustic emission system, demonstrates that a substantial thermal microcrack population is produced in tuff upon heating to 1000oC and initiates after only a couple of hundred degrees. However, despite this, porosity change with increasing temperature is almost negligible and is most likely to be due to their already impressive initial connected porosity (ranging from 45-55%). Permeability measurements show that CI is two orders of magnitude more permeable than its counterparts (about 1 x10-10 m2 compared to about 1 x 10-12 m2). However, interestingly, CI does not show any increase in permeability with heat-treatment temperature, in contrast to NYT and PT who both show an increase of an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917128P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917128P"><span>Statistical analysis of long term (2006-2016) TIR imagery based on Generalized Extreme Value estimator: an application at Pisciarelli volcanic area (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrillo, Zaccaria; Vilardo, Giuseppe; Sansivero, Fabio; Mangiacapra, Annarita; Caliro, Stefano; Caputo, Teresa</p> <p>2017-04-01</p> <p>Quantifying and monitoring energy budgets at <span class="hlt">calderas</span>, released in terms of heat output during unrest periods, is crucial to understand the state of activity, the system evolution and to draw a possible future eruptive scenario. <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, a restless <span class="hlt">caldera</span> in Southern Italy, during the last years is experiencing clear signs of potential reawakening. Indeed, is now more important then ever to consider, analyse and monitor all the potential precursors, contributing to the <span class="hlt">caldera</span> volcanic hazard assessment. We analysed the continuous long term (2006-2016) TIR images night-time collected at Pisciarelli site. This volcanic area, is located above a critical volume which recently showed an increase and clustering of earthquakes distribution and which shows the most impressive gas discharge (mainly H2O and CO2) at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>. We treated in a statistical way the TIR images, defining an anomaly zone, which we compared to a background area. The pixel distributions, as function of the temperature, showed a generalized extreme value structure. The anomaly area, with a long tail toward high temperature values, showed a positive factor form ( f > 0, Frechet distribution). This value was constantly above zero and kept stable along the whole 2006-2016 period, while the scale factor was estimated with a decreasing trend (variance reduction). Pixels of the background TIR images, in contrast, showed a factor form between zero and a weakly negative value (f = 0 or f < 0) Gumbel or Weibull distribution). We used the location parameter as representative of the temperature distribution (which is very near the average temperature) and analysed its trend as function of time, removing the annual variation using a 365.25 days mobile average.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PEPI..253...48C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PEPI..253...48C"><span>Detailed investigation of Long-Period activity at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> by Convolutive Independent Component Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Capuano, P.; De Lauro, E.; De Martino, S.; Falanga, M.</p> <p>2016-04-01</p> <p>This work is devoted to the analysis of seismic signals continuously recorded at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> (Italy) during the entire year 2006. The radiation pattern associated with the Long-Period energy release is investigated. We adopt an innovative Independent Component Analysis algorithm for convolutive seismic series adapted and improved to give automatic procedures for detecting seismic events often buried in the high-level ambient noise. The extracted waveforms characterized by an improved signal-to-noise ratio allows the recognition of Long-Period precursors, evidencing that the seismic activity accompanying the mini-uplift crisis (in 2006), which climaxed in the three days from 26-28 October, had already started at the beginning of the month of October and lasted until mid of November. Hence, a more complete seismic catalog is then provided which can be used to properly quantify the seismic energy release. To better ground our results, we first check the robustness of the method by comparing it with other blind source separation methods based on higher order statistics; secondly, we reconstruct the radiation patterns of the extracted Long-Period events in order to link the individuated signals directly to the sources. We take advantage from Convolutive Independent Component Analysis that provides basic signals along the three directions of motion so that a direct polarization analysis can be performed with no other filtering procedures. We show that the extracted signals are mainly composed of P waves with radial polarization pointing to the seismic source of the main LP swarm, i.e. a small area in the Solfatara, also in the case of the small-events, that both precede and follow the main activity. From a dynamical point of view, they can be described by two degrees of freedom, indicating a low-level of complexity associated with the vibrations from a superficial hydrothermal system. Our results allow us to move towards a full description of the complexity of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6031D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6031D"><span>Time-lapse integrated geophysical imaging of magmatic injections and fluid-induced fracturing causing <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> 1983-84 Unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Crescentini, Luca; Amoruso, Antonella; Del Pezzo, Edoardo; Castellano, Mario</p> <p>2016-04-01</p> <p>Geophysical precursors measured during Unrest episodes are a primary source of geophysical information to forecast eruptions at the largest and most potentially destructive volcanic <span class="hlt">calderas</span>. Despite their importance and uniqueness, these precursors are also considered difficult to interpret and unrepresentative of larger eruptive events. Here, we show how novel geophysical imaging and monitoring techniques are instead able to represent the dynamic evolution of magmatic- and fluid-induced fracturing during the largest period of Unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Italy (1983-1984). The time-dependent patterns drawn by microseismic locations and deformation, once integrated by 3D attenuation tomography and absorption/scattering mapping, model injections of magma- and fluid-related materials in the form of spatially punctual microseismic bursts at a depth of 3.5 km, west and offshore the city of Pozzuoli. The shallowest four kilometres of the crust work as a deformation-based dipolar system before and after each microseismic shock. Seismicity and deformation contemporaneously focus on the point of injection; patterns then progressively crack the medium directed towards the second focus, a region at depths 1-1.5 km south of Solfatara. A single high-absorption and high-scattering aseismic anomaly marks zones of fluid storage overlying the first dipolar centre. These results provide the first direct geophysical signature of the processes of aseismic fluid release at the top of the basaltic basement, producing pozzolanic activity and recently observed via rock-physics and well-rock experiments. The microseismicity caused by fluids and gasses rises to surface via high-absorption north-east rising paths connecting the two dipolar centres, finally beingq being generally expelled from the maar diatreme Solfatara structure. Geophysical precursors during Unrest depict how volcanic stress was released at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> during its period of highest recorded seismicity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..320..128M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..320..128M"><span>Hydrothermal alteration of surficial rocks at Solfatara (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>): Petrophysical properties and implications for phreatic eruption processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mayer, Klaus; Scheu, Bettina; Montanaro, Cristian; Yilmaz, Tim I.; Isaia, Roberto; Aßbichler, Donjá; Dingwell, Donald B.</p> <p>2016-06-01</p> <p>Solfatara crater is located within the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> to the west of Naples (Italy). It is one of the largest fumarolic manifestations known, and the rocks hosting the hydrothermal system are affected by intense hydrothermal alteration. Alteration can result in changes of degassing behavior, and in the formation of a cap rock thereby increasing the probability of phreatic eruptions. Here, we investigate the effects of alunitic (solfataric) alteration on the mineralogy, the physical properties (porosity, density, permeability) and the mechanical properties (strength) of the rocks involved, as well as its influence on fragmentation and ejection behavior. Our results show that the pristine mineralogy of deposits from the vicinity of the Solfatara cryptodome and from Pisciarelli is almost completely replaced by amorphous silica and alunite. The differences in the degree of alteration among the samples series are reflected in the investigated properties and behavior as well as in the analysis of the experimentally generated particles. Alunitic alteration increases porosity and permeability, whereas it reduces density, elastic wave velocity and strength leading to higher fragmentation and ejection speeds for the sample series examined in this study. Our results also show that alteration results in the generation of a high fraction of fines (particle sizes < 10 μm) during fragmentation, mainly composed of alunite crystals. Due to their potential for inducing chronic disease, dispersion of such material should represent a serious health hazard on a local scale and the evaluation of precautions should be considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2998D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2998D"><span>Space-weighted seismic attenuation mapping of the aseismic source of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> 1983-84 unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Siena, Luca; Amoruso, Antonella; Del Pezzo, Edoardo; Castellano, Mario; Wakeford, Zoë; Crescentini, Luca</p> <p>2017-04-01</p> <p>Coda wave attenuation imaging is able to detect fluid/melt accumulation and ancient magmatic bodies in volcanoes. Here, we use recently-developed space-weighting sensitivity functions to invert for the spatial distributions of multi-frequency coda-wave attenuation (Qc-1), measured during the largest monitored unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (1983-84). The kernels are built based on radiative transfer theory, in a diffusive approximation, and are suited for application in highly heterogeneous materials across scales. We integrate our results with relocalised seismicity using the NonLinLoc search-grid algorithm and results of deformation and gravity inversions using 1D starting models. High-attenuation anomalies are spatially correlated with the regions of highest structural complexities and cross faulting. They characterise deep fluid circulation in and around the aseismic roots of the 1534 AD Mount Nuovo eruption and fluid accumulation in the areas of highest hydrothermal hazard. Just offshore Pozzuoli and at the highest frequency (wavelengths of 150 m), the main cause of ground deformation and seismicity during the unrest is an aseismic low-attenuation circular anomaly, similar in shape and nature to those produced by ancient magmatic reservoirs and active sills at other volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BVol...76..812P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BVol...76..812P"><span>Volcanic CO2 flux measurement at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> by tunable diode laser absorption spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedone, M.; Aiuppa, A.; Giudice, G.; Grassa, F.; Cardellini, C.; Chiodini, G.; Valenza, M.</p> <p>2014-04-01</p> <p>Near-infrared room temperature tunable diode lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross sections of the atmospheric plumes of two major fumarolic fields (Solfatara and Pisciarelli). By using a tomographic post-processing routine, we resolved, for each of the two fields, the contour maps of CO2 mixing ratios in the atmosphere, from the integration of which (and after multiplication by the plumes' transport speeds) the CO2 fluxes were finally obtained. We evaluate a total CO2 output from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> fumaroles of ˜490 Mg/day, in line with independent estimates based on in situ (Multi-GAS) observations. We conclude that TDL technique may enable CO2 flux quantification at other volcanoes worldwide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70178406','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70178406"><span>The Late-Holocene evolution of the Miseno area (south-western <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>) as inferred by stratigraphy, petrochemistry and 40Ar/39Ar geochronology:Chapter 6 in Volcanism in the Campania Plain — Vesuvius, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Ignimbrites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Insinga, Donatella; Calvert, Andrew T.; Lanphere, Marvin A.; Morra, Vincenzo; Perrotta, Annamaria; Sacchi, Marco; Scarpati, Claudio; Saburomaru, James; Fedele, Lorenzo</p> <p>2006-01-01</p> <p>This study on terrestrial and marine successions increases the understanding of the Late-Holocene volcanological and stratigraphical evolution of the south-western part of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>.Stratigraphic data derived from field studies of two major tuff vents located along the coastal zone, namely Porto Miseno and Capo Miseno, clearly indicate that the Porto Miseno tuff ring slightly predates the Capo Miseno tuff cone. 40Ar/39Ar step-heating experiments, carried out on fresh sanidine separates from pumice samples, yielded a plateau age of 5090±140 yr BP for Capo Miseno and 6490±510 yr BP for Porto Miseno vent, thus confirming field observations.The volcanoclastic input derived from this recent and intense eruptive activity played a major role in the inner-shelf stratigraphic evolution of the Porto Miseno Bay deposits that have been drilled up to 40 m depth off the crater rim. The cored succession is characterised by transgressive marine deposits (mostly volcanic sand) with two intercalated peat layers (t1 and t2), dated at 3560±40 yr BP and 7815±55 yr BP (14C), respectively, interbedded with a 1–5 m thick pumice layer (tephra C). Peat layers have been chronostratigraphically correlated with two widespread paleosols onland while petrochemical analyses allowed us to correlate tephra C with the Capo Miseno tuff cone deposits.The results presented in this study imply a Late-Holocene volcanic activity that is also well preserved in the marine record in this sector of the <span class="hlt">caldera</span> where a new chronostratigraphic reconstruction of the eruptive events is required in order to better evaluate the hazard assessment of the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015445','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015445"><span>The <span class="hlt">campi</span> <span class="hlt">flegrei</span> (Italy) geothermal system: A fluid inclusion study of the mofete and San Vito fields</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>de, Vivo B.; Belkin, H.E.; Barbieri, M.; Chelini, W.; Lattanzi, P.; Lima, A.; Tolomeo, L.</p> <p>1989-01-01</p> <p> Vito 3 cores show an approach to fluid/rock Sr equilibrium with a fluid similar to modern ocean water in 87Sr/86Sr ratio. The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic system has evolved undersaturated products, mostly trachyte, and defines a large (??? 12 km) <span class="hlt">caldera</span>. The hydrothermal system developed in this location can be used as an analog for fossil systems in similar trachytic environments. The potential for ore mineralization is expressed by the recognition, from fluid inclusion and drilling data, of ore-forming environments such as boiling and brine stratification. ?? 1989.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JVGR..189..202S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JVGR..189..202S"><span>The relevance of the 1198 eruption of Solfatara in the Phlegraean Fields (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>) as revealed by medieval manuscripts and historical sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scandone, R.; D'Amato, J.; Giacomelli, L.</p> <p>2010-01-01</p> <p>The Phlegraean Fields (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>) <span class="hlt">caldera</span> in Italy had one well-documented eruption during the historical period (1538). Another eruption at Solfatara in 1198 is reported by sixteenth and seventeenth-century scholars, and has been commonly regarded as uncertain. In this paper we first discuss the circumstantial evidence and report of this eruption, then discuss the relevance of drawings made in the thirteenth through the fifteenth century illustrating the Solfatara and the primary literary and historical sources describing the site. We infer that the eruption was at most a minor phreatic explosion and we explore the conditions that may have led to the occurrence of this event and the establishment of a small crater pool subsequently used as a thermal bath from the later Middle Ages onward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JVGR...91..167O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JVGR...91..167O"><span>Correlation of deposits and vent locations of the proximal Campanian Ignimbrite deposits, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, based on natural remanent magnetization and anisotropy of magnetic susceptibility characteristics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ort, Michael H.; Rosi, Mauro; Anderson, Charles D.</p> <p>1999-08-01</p> <p>Correlation of the distal deposits of the Campanian Ignimbrite with their proximal equivalents in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> is complicated by a lack of medial exposures, complex and limited proximal stratigraphic sections, and large lateral facies changes. Paleomagnetic data from 10 sites in and near the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> yield natural remanent magnetizations (NRM) that are statistically indistinguishable from the distal Campanian Ignimbrite. In addition, their virtual geomagnetic pole (VGP) yields a possible correlation with Lac du Bouchet, France, secular variation data that indicate an age of approximately 32,850 14C years. The secular variation curve at this age was only briefly at this VGP, and did not return to it for >10,000 years, so the paleomagnetic correlation of proximal and distal deposits is unique and robust. The date is consistent with 14C dates from the Campanian Ignimbrite, but younger than 39Ar/ 40Ar dates for the same rocks. This suggests that a better correction factor for cosmic flux for this time period is needed to calibrate older 14C dates. Anisotropy of magnetic susceptibility (AMS) data show that the proximal deposits have an oblate (disk-shaped), poorly lineated magnetic fabric. The distal deposits are much better lineated. The difference may be due to chaotic depositional currents in the proximal areas, in which particles were not well aligned. With greater distance of travel, and loss of energy, particles within the flow became aligned and developed stronger AMS lineations. Early eruptions of the Piperno Tuff were from a central vent north of Pozzuoli, whereas later tuffs that underlie the Breccia Museo may have been emplaced by flows associated with ring vents located on the northern and southern <span class="hlt">caldera</span> margins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.7996M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.7996M"><span>Experimental investigations on the explosivity of steam-driven eruptions: A case study of Solfatara volcano (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montanaro, Cristian; Scheu, Bettina; Mayer, Klaus; Orsi, Giovanni; Moretti, Roberto; Isaia, Roberto; Dingwell, Donald B.</p> <p>2016-11-01</p> <p>Steam-driven eruptions, both phreatic and hydrothermal, expel exclusively fragments of non-juvenile rocks disintegrated by the expansion of water as liquid or gas phase. As their violence is related to the magnitude of the decompression work that can be performed by fluid expansion, these eruptions may occur with variable degrees of explosivity. In this study we investigate the influence of liquid fraction and rock petrophysical properties on the steam-driven explosive energy. A series of fine-grained heterogeneous tuffs from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> were investigated for their petrophysical properties. The rapid depressurization of various amounts of liquid water within the rock pore space can yield highly variable fragmentation and ejection behaviors for the investigated tuffs. Our results suggest that the pore liquid fraction controls the stored explosive energy with an increasing liquid fraction within the pore space increasing the explosive energy. Overall, the energy released by steam flashing can be estimated to be 1 order of magnitude higher than for simple (Argon) gas expansion and may produce a higher amount of fine material even under partially saturated conditions. The energy surplus in the presence of steam flashing leads to a faster fragmentation with respect to gas expansion and to higher ejection velocities imparted to the fragmented particles. Moreover, weak and low permeability rocks yield a maximum fine fraction. Using experiments to unravel the energetics of steam-driven eruptions has yielded estimates for several parameters controlling their explosivity. These findings should be considered for both modeling and evaluation of the hazards associated with steam-driven eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011BVol...73..767C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011BVol...73..767C"><span>Assessment of pre-crisis and syn-crisis seismic hazard at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Mt. Vesuvius volcanoes, Campania, southern Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Convertito, Vincenzo; Zollo, Aldo</p> <p>2011-08-01</p> <p>In this study, we address the issue of short-term to medium-term probabilistic seismic hazard analysis for two volcanic areas, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> and Mt. Vesuvius in the Campania region of southern Italy. Two different phases of the volcanic activity are considered. The first, which we term the pre-crisis phase, concerns the present quiescent state of the volcanoes that is characterized by low-to-moderate seismicity. The second phase, syn-crisis, concerns the unrest phase that can potentially lead to eruption. For the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> case study, we analyzed the pattern of seismicity during the 1982-1984 ground uplift episode (bradyseism). For Mt. Vesuvius, two different time-evolutionary models for seismicity were adopted, corresponding to different ways in which the volcano might erupt. We performed a site-specific analysis, linked with the hazard map, to investigate the effects of input parameters, in terms of source geometry, mean activity rate, periods of data collection, and return periods, for the syn-crisis phase. The analysis in the present study of the pre-crisis phase allowed a comparison of the results of probabilistic seismic hazard analysis for the two study areas with those provided in the Italian national hazard map. For the Mt. Vesuvius area in particular, the results show that the hazard can be greater than that reported in the national hazard map when information at a local scale is used. For the syn-crisis phase, the main result is that the data recorded during the early months of the unrest phase are substantially representative of the seismic hazard during the whole duration of the crisis.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16...26P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16...26P"><span>Volcanic CO2 mapping and flux measurements at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> by Tunable Diode Laser absorption Spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedone, Maria; Aiuppa, Alessandro; Giudice, Gaetano; Grassa, Fausto; Chiodini, Giovanni; Valenza, Mariano</p> <p>2014-05-01</p> <p>Near-infrared room-temperature Tunable Diode Lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in Volcanology are still limited to a few examples. Here, we explored the potentiality of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) to measurement of volcanic CO2 flux emissions. Our field tests were conducted at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (near Pozzuoli, Southern Italy), where the GasFinder was used (during three campaigns in October 2012, January 2013 and May 2013) to repeatedly measure the path-integrated concentrations of CO2 along cross-sections of the atmospheric plumes of the two main fumarolic fields in the area (Solfatara and Pisciarelli). By using ad-hoc designed field-set-up and a tomographic post-processing routine, we resolved, for each of the 2 manifestations, the contour maps of CO2 concentrations in their atmospheric plumes, from the integration of which (and after multiplication by the plumes' transport speeds) the CO2 fluxes were finally obtained [1]. The so-calculated fluxes average of 490 tons/day, which agrees well with independent evaluations of Aiuppa et al. (2013) [2] (460 tons/day on average), and support a significant contribution of fumaroles to the total CO2 budget. The cumulative (fumarole [this study] +soil [2]) CO2 output from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is finally evaluated at 1600 tons/day. The application of lasers to volcanic gas studies is still an emerging (though intriguing) research field, and requires more testing and validation experiments. We conclude that TDL technique may valuably assist CO2 flux quantification at a number of volcanic targets worldwide. [1] Pedone M. et al. (2013) Gold2013:abs:5563, Goldschmidt Conference, session 11a. [2] Aiuppa A. et al. (2013) Geochemistry Geophysics Geosystems. doi: 10.1002/ggge.20261. [3] Chiodini G. et al. (2010) Journal of Geophysical Research, Volume 115, B03205. doi:10.1029/2008JB006258.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714510P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714510P"><span>Observatory response to a volcanic crisis: the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> simulation exercise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Papale, Paolo; De Natale, Giuseppe</p> <p>2015-04-01</p> <p>In Febraury 2014 a simulation exercise was conducted at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, in order to test the scientific response capabilities and the effectiveness of communication with Civil Protection authorities. The simulation was organized in the frame of the EU-VUELCO project, and involved the participation of the Osservatorio Vesuviano of INGV (INGV-OV) corroborated by other INGV scientists involved for their specific competencies; and the Italian Civil Protection, which was supported by an expert team formed by selected experts from the Italian academy and by VUELCO scientists from several EU and Latin American countries. The simulation included a previously appointed group of four volcanologists covering a range of expertise in volcano seismology, geodesy, geochemistry, and with experience both on the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> system and on other volcanic systems and crises in the world. The duty of this 'volcano team' was that of producing consistent sets of signals, that were sent to INGV-OV at the beginning of each simulation phase. In turn, the observatory response was that of i) immediately communicate the relevant observations to the Civil Protection; ii) analyze the synthetic signals and observations and extract a consistent picture and interpretation, including the analysis and quantification of uncertainties; iii) organize all the information produced in a bulletin, that was sent to the Civil Protection at the end of each simulation phase and that contained, according to national established agreements, a) the information available, and b) its interpretation including forecasts on the possible medium-short term evolution. The test included four simulation phases and it was blind, as only the volcano team knew the evolution and the final outcome; the volcano team was located at the INGV buildings in Rome, far from INGV-OV in Naples and the Civil Protection Dept. still in Rome, and with no contacts with any of them for the entire duration of the simulation. In this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9613W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9613W"><span>Laboratory experiments and continuous fluid monitoring at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> to understand pressure transients in hydrothermal systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woith, Heiko; Mangiacapra, Annarita; Chiodini, Giovanni; Pilz, Marco; Walter, Thomas</p> <p>2015-04-01</p> <p>The hydrothermal system beneath <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is strongly affected by sub-surface processes as manifested by the existence of a geothermal "plume" below Solfatara (Bruno et al. 2007), associated with formation of new fumaroles and the spatial pattern of exhalation vents. Within the frame of MED-SUV (The MED-SUV project has received funding from the European Union Seventh Framework Programme (FP7) under Grant agreement no 308665), pressure tansients in the hydrothermal system of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> shall be studied using a combination of laboratory experiments and continuous pressure/temperature monitoring at fumaroles, mudpools, hot springs, and geothermal wells. Four groundwater monitoring sites were installed in September 2013: one in the Fangaia mud pool inside Solfatara and three within the geothermal area of Agnano, which is located roughly 3 km to the East of the Solfatara crater. In 2014 additional sensors were installed in Pisciarelli. Autonomous devices are being used to record the water level and water temperature at 10 minute intervals. Records reveal significant changes of the hydrothermal system in September 2013 at the Agnano main spring during the night from 23 to 24 September. Both, the water level and the water temperature dropped significantly, confirmed by visual inspection of the spa operators. The pool of the main spring almost emptied and the flow rate was significantly reduced, implying a profound change in the system. Similar water level drops occurred in the following months. Gas bubbles are likely to play a major role with respect to spatio-temporal variations in shallow fluid systems below Solfatara. Thus, additional to the field measurements we investigate potential bubble-related mechanisms capable to increase fluid pressure. The BubbleLab at GFZ has been setup. We are able to simulate earthquake ground motions with a shaking table, track the size and velocity of rising bubbles via a camera system, and quantify transients with a set of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.G11A1061M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.G11A1061M"><span>A new method to assess long term small sea-bottom vertical displacement in shallow water from bottom pressure sensor: the case of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malservisi, R.; Chierici, F.; Iannaccone, G.; Guardato, S.; Pignagnoli, L.; Locritani, M.; Embriaco, D.; Donnarumma, G. P.; Rodgers, M.; Beranzoli, L.</p> <p>2016-12-01</p> <p>We present a new methodology aimed at assessing long term small vertical seafloor deformation in shallow water environments by using Bottom Pressure Recorder (BPR) measurements jointly with ancillary sea level, water column and barometric data. These measurements are presently acquired only in areas where the amount of vertical deformation is large and in deep water environment, where the noise induced by the sea state and other near surface disturbances is low. We applied the method to the data acquired in 2011 by a BPR deployed at about 96 m depth in the marine sector of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span>, during a quasi-symmetric seafloor uplift episode of a few centimeters amplitude. The method provides an estimation of the vertical uplift of the <span class="hlt">caldera</span> of 2.5 +/- 1.3 cm achieving an unprecedented level of precision in the measurement of the seafloor vertical deformation in shallow water. We reached this result by taking into account the contribution of the BPR instrumental drift and the contribution of the sea water density variations, which can affect the measurement on the order of tens of centimeters. The estimation of the vertical deformation obtained in this way compares favorably with data acquired by a land based GPS station, which is located at the same distance from the area of maximum deformation as the BPR</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.7775C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.7775C"><span>A new method to assess long-term sea-bottom vertical displacement in shallow water using a bottom pressure sensor: Application to <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chierici, Francesco; Iannaccone, Giovanni; Pignagnoli, Luca; Guardato, Sergio; Locritani, Marina; Embriaco, Davide; Donnarumma, Gian Paolo; Rodgers, Mel; Malservisi, Rocco; Beranzoli, Laura</p> <p>2016-11-01</p> <p>We present a new methodology using bottom pressure recorder (BPR) measurements in conjunction with sea level, water column, and barometric data to assess the long-term vertical seafloor deformation to a few centimeters accuracy in shallow water environments. The method helps to remove the apparent vertical displacement on the order of tens of centimeters caused by the BPR instrumental drift and by seawater density variations. We have applied the method to the data acquired in 2011 by a BPR deployed at 96 m depth in the marine sector of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span>, during a seafloor uplift episode of a few centimeters amplitude, lasted for several months. The method detected a vertical uplift of the <span class="hlt">caldera</span> of 2.5 ± 1.3 cm achieving an unprecedented level of precision in the measurement of the submarine vertical deformation in shallow water. The estimated vertical deformation at the BPR also compares favorably with data acquired by a land-based GPS station located at the same distance from the maximum of the modeled deformation field. While BPR measurements are commonly performed in deep waters, where the oceanic noise is relatively low, and in areas with rapid, large-amplitude vertical ground displacement, the proposed method extends the capability of estimating vertical uplifts from BPR time series to shallow waters and to slow deformation processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006Geo....34..937M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006Geo....34..937M"><span>Magma chamber of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> supervolcano at the time of eruption of the Campanian Ignimbrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marianelli, Paola; Sbrana, Alessandro; Proto, Monica</p> <p>2006-11-01</p> <p>A supereruption that occurred in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area, Italy, ca. 39 ka had regional- and global-scale environmental impacts and deposited the Campanian Ignimbrite (CI). We attempt to shed light on critical aspects of the eruption (depth of magma chamber, intensive pre-eruptive magma conditions) and the large-volume magma plumbing system on the basis of information derived from analyzing melt inclusion (MI) data. To achieve these aims, we provide new measurements of homogenization temperatures and values of dissolved H2O within phenocryst-hosted MIs from pumices erupted during different phases of the CI eruption. The MI data indicate that a relatively homogeneous overheated trachytic magma resided within a relatively deep magma chamber. Dissolved water contents in MIs indicate that prior to the eruption the magma chamber underwent radical changes related to differential upward movement of magma. Decompression of the rising trachytic magma caused a decrease in water solubility and crystallization, and trachytic bodies were emplaced at very shallow depths. The proposed eruptive model links portions of the main magma chamber and apophyses with specific eruptive units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016632','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016632"><span>14C age of the "Museum Breccia" (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>) and its relevance for the origin of the Campanian Ignimbrite</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lirer, L.; Rolandi, G.; Rubin, M.</p> <p>1991-01-01</p> <p>Field stratigraphic investigations and AMS 14C dating of carbon particles in paleosols has resulted in a framework of the sequence and age of the pyroclastic products in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area of Southern Italy. The Museum Breccia cannot be the early phase of the Campanian Ignimbrite, as was previously believed, but is from a smaller and later eruption with an age of approximately 17,900 y B.P. This date also precludes its correlation with the Neapolitan Yellow Tuff (12,000 y B.P.). ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3150J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3150J"><span>Authigenic Mineral Cycling in Roman Seawater Concrete with <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Pumiceous Ash Pozzolan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jackson, M. D.; Mulcahy, S. R.; Chen, H.; Li, Q.; Cappelletti, P.; Carraro, C.; Wenk, H. R.</p> <p>2015-12-01</p> <p>Alteration of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> pumiceous ash in Roman concrete harbor structures along the central Italian coast produced zeolite and Ca-silicate minerals that have reinforced cementitious fabrics for >2000 years. X-ray microdiffraction experiments and electron microprobe analyses show that diverse alteration paths produced authigenic phillipsite and Al-tobermorite in the pyroclasts, pores, and cementing matrix of mortars in Romacons drill cores from Portus Cosanus, Portus Neronis, and Baianus Sinus. These minerals have cation exchange capabilities for some radionuclides and heavy metal cations and are candidate sorbents for concrete waste encapsulations. Compositions of phillipsite in certain Portus Cosanus and Portus Neronis pumice clasts are similar to those in the Neapolitan Yellow Tuff. Dissolution of this phillipsite and alkali feldspar produced new, authigenic phillipsite with less Si, greater Al and Ca, Al-tobermorite, and poorly-crystalline binder in pumice vesicles. Conversely, alteration of trachytic glass to clay mineral (nontronite) in a Baianus Sinus tuff clast is associated with new, authigenic phillipsite and Al-tobermorite in the tuff and cementing matrix. The Al-tobermorite has lower Al/(Si+Al) and Ca/(Si+Al) compared to Al-tobermorite in relict lime clasts. These more siliceous crystals, similar to those in hydrothermally-altered basalt, have 11.3 Å d-spacing in [001]. Raman spectra show symmetrical bending of Si-O-Si and Si-O-Al linkages, Si-O and Si-Al symmetrical stretching, and possible Q3 Si and Al tetrahedral peaks that suggest cross-linking of silicate chains-an important factor in cation exchange. The authigenic crystals refine pore space, contribute to binding in interfacial zones, and obstruct microcrack propagation. The well-constrained history of temperature variations and seawater immersion could provide further information for understanding alteration in volcanoclastic deposits and predicting regenerative processes in high performance</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812888C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812888C"><span>Seafloor slow vertical displacement inferred by sea bottom pressure measurements in shallow water: an application to the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic area</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chierici, Francesco; Pignagnoli, Luca; Iannaccone, Giovanni; Guardato, Sergio; Locritani, Marina; Embriaco, Davide; Donnarumma, Gian Paolo; La Rocca, Adriano; Pinto, Salvatore; Beranzoli, Laura</p> <p>2016-04-01</p> <p>The vertical component of sea floor displacement in tectonic or volcanically active areas can be observed using sea bottom pressure recorders. These measurements are usually acquired in areas affected by strong dynamics with large vertical displacement and in deep water, where the noise induced by the sea state is low. Under these conditions the contribution of the variation of sea water density and the contribution of the instrumental drift - a typical feature of the bottom pressure recorders - can be negligible. We have developed a new methodology to monitor vertical sea floor displacement both in areas with small and slow deformation, and in shallow water. We take advantage of bottom pressure recorder data, augmented with ancillary sea level, barometric and water physical parameters measurements. We have applied this method to the data collected by a bottom pressure recorder deployed at 100 m w.d. in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">Caldera</span> as part of CUMAS multiparameter monitoring system. During several months of 2011 we have observed a small uplift episode related to the bradiseismic activity of the area. These observations are compatible with other geodetic data recorded in the region and provide unprecedented measurements of the vertical deformation in the marine area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210531C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210531C"><span>The Italy's D.P.C. - I.N.G.V. Project UNREST: Realization of an integrated method for the definition of the unrest phases at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Civetta, Lucia; Del Pezzo, Edoardo</p> <p>2010-05-01</p> <p>In this poster we present the framework of the Project "UNREST" and the preliminary results obtained in the first 18 months of activity. The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> resurgent <span class="hlt">caldera</span>, where several hundred thousands people live, have been characterized during last decades by several bradiseismic crises which determined the partial evacuation of the population, as for the crises in 1969-72 and 1982-84. Recent studies have revealed a process of unrest which continues since the fifties, and which presents characteristics similar to the several centuries-decades long unrest period which led to the last eruption in AD 1538. In the frame of last INGV-DPC Agreement a method has been developed, which allows accounting of any information and associated uncertainty coming from historical, field, and modelling studies, and from the monitoring network, providing a probability on the state of the volcano and on the occurrence of an eruption. In the present project this method is explored and developed, particularly through the experimentation of methods for the definition of reference parameters and thresholds, and of criteria and procedures to make it an operational tool useful for volcano surveillance and crisis management. The research in the project include the following points: a) Definition of the reference database for the validation of models of pre-eruptive dynamics. The database will include geologic, geophysic, geochemical, hydrological and hystorical data. b) Quantitative analysis of measured signals, and formulation of hypotheses on source mechanisms. c) Definition of a general conceptual model for the magma-rocks-geothermal system at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. d) Physico-mathematical modelling and numerical simulation of the magmatic and geothermal process dynamics, and of the space-time relationships between such dynamics and the geophysical and geochemical signals measured at the surface. e) Definition of the critical parameters for the definition of the different unrest phases, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH32A..08C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH32A..08C"><span>Integrated multi-parameters Probabilistic Seismic Landslide Hazard Analysis (PSLHA): an innovative approach in the active volcano-tectonic area of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caccavale, M.; Matano, F.; Sacchi, M.; Somma, R.; Troise, C.; De Natale, G.</p> <p>2013-12-01</p> <p>The western coastal sector of Campania region (southern Italy) is characterised by the presence of the active volcano-tectonic area of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. This area represents a very particular and interesting case-study for a probabilistic seismic hazard analysis (PSHA). The principal seismic source, related with the <span class="hlt">caldera</span>, is not clearly constrained in the on-shore and off-shore areas. The well-known and monitored phenomenon of bradyseism affecting a large portion of case-study area is not modelled in the standard PSHA approach. From the environmental point of view the presence of very high exposed values in terms of population, buildings, infrastructures and palaces of high archaeological, natural and artistic value, makes this area a strategic natural laboratory to develop new methodologies. Moreover the geomorphological and geo-volcanological features lead to a heterogeneous coastline, made up by both beach and tuff cliffs, rapidly evolving for erosion and landslide (i.e. mainly rock fall and rock slide) phenomena that represent an additional hazard aspect. In the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> the possible occurrence of a moderate/large seismic event represents a serious threat for the inhabitants, for the infrastructures as well as for the environment. In the framework of Italian MON.I.C.A project (sinfrastructural coastlines monitoring) an innovative and dedicated probabilistic methodology has been applied to identify the areas with higher tendency of landslide occurrence due to the seismic effect. Resident population reported the occurrence of some small rock falls along tuff quarry slopes during the main shocks of the 1982-84 bradyseismic events. The PSHA methodology, introduced by Cornell (1968), combines the contributions to the hazard from all potential sources of earthquakes and the average activity rates associated to each seismogenic zone considered. The result of the PSHA is represented by the spatial distribution of a ground-motion (GM) parameter A, such as Peak</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9819T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9819T"><span>Definition of Brittle Ductile Transition of the upper crust beneath the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>-Ischia Volcanic District and its impact on natural seismicity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tizzani, Pietro; Castaldo, Raffaele; De Novellis, Vincenzo; Santilano, Alessandro; Gola, Gianluca; Pepe, Susi; D'Auria, Luca; Solaro, Giuseppe</p> <p>2016-04-01</p> <p>The thermo-rheology behaviour of the rocks is a crucial aspect to understand the mechanical behaviour of the crust of tectonically active area. As a consequence, several studies have been performed since last decades in order to clarify the role of thermic state in the evolution of volcanic areas. In this framework, the knowledge of the Brittle-Ductile transition inside the upper crust may provide insights to verify the roles that some hypothesized mechanisms, such as slab pull, crustal delamination might have played in the evolution of a tectonically active region. The goal of our study was the 3D imaging of the crust rheology beneath the active <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>-Ischia Volcanic District and its impact on natural seismicity. Despite many works have been done on the internal structure of the active volcanoes, the determination of the 3D rheological stratification of the crust below the <span class="hlt">caldera</span> has not yet been tackled. To fill this gap of knowledge, we proposed the definition of 3D geometry of the Brittle-Ductile transition calculated via numerical optimization modelling based on geological, geochemical, and geophysical available data. We first performed a 3D numerical modelling of thermal field by using the a priori geological and geophysical information starting to thermal proprieties and mechanical heterogeneities of the crust beneath the <span class="hlt">caldera</span>. We developed a suitable 3D conductive/convective time-dependent thermal numerical model solving the Fourier equation and further we used the retrieved thermal model to image a 3D rheological stratification of the shallow crust below the volcanic district. Finally we demonstrate the role of the crustal rheology on seismicity cut off and its implication on maximum expected earthquakes magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917805S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917805S"><span>Sensitivity tests and ensemble hazard assessment for tephra fallout at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Selva, Jacopo; Costa, Antonio; De Natale, Giuseppe; Di Vito, Mauro; Isaia, Roberto; Macedonio, Giovanni</p> <p>2017-04-01</p> <p>We present the results of a statistical study on tephra dispersion in the case of reactivation of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcano. We considered the full spectrum of possible eruptions, in terms of size and position of eruptive vents. To represent the spectrum of possible eruptive sizes, four classes of eruptions were considered. Of those only three are explosive (small, medium, and large) and can produce a significant quantity of volcanic ash. Hazard assessments are made through dispersion simulations of ash and lapilli, considering the full variability of winds, eruptive vents, and eruptive sizes. The results are presented in form of four families of hazard curves conditioned to the occurrence of an eruption: 1) small eruptive size from any vent; 2) medium eruptive size from any vent; 3) large eruptive size from any vent; 4) any size from any vent. The epistemic uncertainty (i.e. associated with the level of scientific knowledge of phenomena) on the estimation of hazard curves was quantified making use of alternative scientifically acceptable approaches. The choice of such alternative models is made after a comprehensive sensitivity analysis which considered different weather databases, alternative modelling of the possible opening of eruptive vents, tephra total grain-size distributions (TGSD), relative mass of fine particles, and the effect of aggregation. The results of this sensitivity analyses show that the dominant uncertainty is related to the choice of TGSD, mass of fine ash, and potential effects of ash aggregation. The latter is particularly relevant in case of magma-water interaction during an eruptive phase, when most of the fine ash can form accretionary lapilli that could contribute significantly in increasing the tephra load in the proximal region. Relatively insignificant is the variability induced by the use of different weather databases. The hazard curves, together with the quantification of epistemic uncertainty, were finally calculated through a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V21B2101S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V21B2101S"><span>Magmatic Processes in Monogenetic Eruptions, Procida Island, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy: Geochemical Evidence From Melt Inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Severs, M. J.; Fedele, L.; Esposito, R.; Bodnar, R.; Petrosino, P.; Lima, A.; de Vivo, B.; Shimizu, N.</p> <p>2008-12-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is an active volcanic complex located in the greater Naples area, which has produced more than 50 eruptions over the past 60,000 years. These have ranged from small eruptions such as Monte Nuovo eruption of 1538 CE to extremely large eruptions such as the Campanian Ignimbrite (150-200 DRE; Barbieri et al., 1978). The volcanic field includes the mainland area located to the west of Naples and also the two islands of Ischia and Procida. The volcanic products range from basalts to shoshonitic phonolites and trachytes, with the more evolved magmas being more abundant. Three eruptive units from Procida Island have been studied to observe geochemical trends over time within a small area and to better understand magmatic processes between monogenetic eruptions. Juvenile samples from Pozzo Vecchio, Breccia Museo, and Solchiara were collected to examine the geochemistry of the mineral phases present and melt inclusions (MIs) found within the phenocrysts. Solchiara contained phenocrysts of olivine and clinopyroxene, whereas Breccia Museo and Pozzo Vecchio samples contained clinopyroxene and sanidine as the dominant phenocryst phases. Melt inclusions from Solchiara have narrow compositional ranges in major and trace elements (i.e., CaO, TiO2, Zr, Dy, La) over a large range in SiO2 contents (47 to 55 wt%) while MI from the Breccia Museo have a limited range of SiO2 contents (57 to 61 wt%) with a wider range for major and trace elements (i.e., FeO, Al2O3, CaO, La, Th, Rb). Pozzo Vecchio MI from clinopyroxene and sanidine define different chemical compositions, but petrographic evidence does not suggest a xenocrystic origin for either mineral phase. This suggests that Pozzo Vecchio is the result of magma mixing. Modeling of fractional crystallization of olivine, clinopyroxene, and sanidine are capable of producing most of the trends in major and trace elements between the most primitive samples to the most evolved samples. Volatile concentrations between the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BVol...78...79T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BVol...78...79T"><span>Suitability of energy cone for probabilistic volcanic hazard assessment: validation tests at Somma-Vesuvius and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tierz, Pablo; Sandri, Laura; Costa, Antonio; Zaccarelli, Lucia; Di Vito, Mauro Antonio; Sulpizio, Roberto; Marzocchi, Warner</p> <p>2016-11-01</p> <p>Pyroclastic density currents (PDCs) are gravity-driven hot mixtures of gas and volcanic particles which can propagate at high speed and cover distances up to several tens of kilometers around a given volcano. Therefore, they pose a severe hazard to the surroundings of explosive volcanoes able to produce such phenomena. Despite this threat, probabilistic volcanic hazard assessment (PVHA) of PDCs is still in an early stage of development. PVHA is rooted in the quantification of the large uncertainties (aleatory and epistemic) which characterize volcanic hazard analyses. This quantification typically requires a big dataset of hazard footprints obtained from numerical simulations of the physical process. For PDCs, numerical models range from very sophisticated (not useful for PVHA because of their very long runtimes) to very simple models (criticized because of their highly simplified physics). We present here a systematic and robust validation testing of a simple PDC model, the energy cone (EC), to unravel whether it can be applied to PVHA of PDCs. Using past PDC deposits at Somma-Vesuvius and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy), we assess the ability of EC to capture the values and variability in some relevant variables for hazard assessment, i.e., area of PDC invasion and maximum runout. In terms of area of invasion, the highest Jaccard coefficients range from 0.33 to 0.86 which indicates an equal or better performance compared to other volcanic mass-flow models. The p values for the observed maximum runouts vary from 0.003 to 0.44. Finally, the frequencies of PDC arrival computed from the EC are similar to those determined from the spatial distribution of past PDC deposits, with high PDC-arrival frequencies over an ˜8-km radius from the crater area at Somma-Vesuvius and around the Astroni crater at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. The insights derived from our validation tests seem to indicate that the EC is a suitable candidate to compute PVHA of PDCs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8264T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8264T"><span>Interaction between hydrothermal and magmatic systems: modelling of magmatic gas release and ascent at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Todesco, Micol; Afanasyev, Andrey; Montagna, Chiara Paola; Longo, Antonella</p> <p>2016-04-01</p> <p>We model the perturbation of a hydrothermal system caused by the gas release from sub-surface magma chambers. First, we simulate the evolution of the magmatic system composed by two magma reservoirs: a small and shallow chamber, filled with degassed phonolite, connected to a deeper reservoir of gas-rich shoshonite through a vertical dyke. The fluid-dynamics governing the replenishment of the upper chamber is computed with a 2D code solving conservation equations of mass, momentum and energy for a homogeneous multicomponent, multiphase Newtonian mixture, accounting for exsolution and dissolution of volatiles (H2O+CO2). We then assume that the volatiles that accumulate at the top of the upper chamber, escape from the reservoir and enter a steady state hydrothermal system. The response of the hydrothermal circulation is simulated with two multi-phase, multi-component porous media codes (MUFITS and TOUGH2) that describe the propagation of magmatic volatiles toward the surface. We create a simple model of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> hydrothermal system covering both shallow and deep regions where the temperature exceeds the critical temperature for water. Simulation results suggest that the rate at which volatiles are released from the magma chamber, the permeability distribution and the conditions of the hydrothermal system when degassing takes place can determine very different evolutions: accordingly, carbon dioxide may reach the surface within a time span ranging from weeks to millennia. The simulations indicate also that a single unrest event, associated with volatiles release from the chamber, can result in a periodic behaviour of observable parameters such as gas flux and fumarole composition. Duration of the period is of the order of 10 years, which is comparable with the time span between major unrest events observed at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815633S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815633S"><span>A temporal record of pre-eruptive magmatic volatile contents at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>: Insights from texturally-constrained apatite analyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stock, Michael J.; Isaia, Roberto; Humphreys, Madeleine C. S.; Smith, Victoria C.; Pyle, David M.</p> <p>2016-04-01</p> <p>Apatite is capable of incorporating all major magmatic volatile species (H2O, CO2, S, Cl and F) into its crystal structure. Analysis of apatite volatile contents can be related to parental magma compositions through the application of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994). Once included within phenocrysts, apatite inclusions are isolated from the melt and preserve a temporal record of magmatic volatile contents in the build-up to eruption. In this work, we measured the volatile compositions of apatite inclusions, apatite microphenocrysts and pyroxene-hosted melt inclusions from the Astroni 1 eruption of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy (Stock et al. 2016). These data are coupled with magmatic differentiation models (Gualda et al., 2012), experimental volatile solubility data (Webster et al., 2014) and thermodynamic models of apatite compositional variations (Piccoli and Candela, 1994) to decipher pre-eruptive magmatic processes. We find that apatite halogen/OH ratios decreased through magmatic differentiation, while melt inclusion F and Cl concentrations increased. Melt inclusion H2O contents are constant at ~2.5 wt%. These data are best explained by volatile-undersaturated differentiation over most of the crystallisation history of the Astroni 1 melt, with melt inclusion H2O contents reset at shallow levels during ascent. Given the high diffusivity of volatiles in apatite (Brenan, 1993), the preservation of volatile-undersaturated melt compositions in microphenocrysts suggests that saturation was only achieved 10 - 103 days before eruption. We suggest that late-stage transition into a volatile-saturated state caused an increase in magma chamber overpressure, which ultimately triggered the Astroni 1 eruption. This has major implications for monitoring of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and other similar volcanic systems. Piccoli and Candela, 1994. Am. J. of Sc., 294, 92-135. Stock et al., 2016, Nat. Geosci. Gualda et al., 2012. J. Pet., 53, 875</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4511F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4511F"><span>Real-time quadrupole mass spectrometry of hydrothermal gases from the unstable Pisciarelli fumaroles (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>): trends, challenges and processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedele, Alessandro; Pedone, Maria; Moretti, Roberto; Somma, Renato; Wiersberg, Thomas; Troise, Claudia; De Natale, Giuseppe</p> <p>2017-04-01</p> <p>Volcanic gases sampling and post-collection chemical determination in a laboratory may preclude any real-time continuous monitoring of volcanic activity. In this work we describe the development, and show the advantages, of a system used for the continuous monitoring of fumarolic gases discharges from the Pisciarelli site (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy) based on a commercial quadrupole mass spectrometer (QMS-301). Although numerous technical problems were addressed due to the ephemeral emission point, coupled with the harsh environment, we also report measurements of the chemical composition of the major gas species emitted from the fumarole and a record were obtained for two different periods. The CO2/H2S, H2S/H2, He/CO2 and CH4/CO2 molar ratios were investigated in order to detect magmatic and/or hydrothermal components in the system, while the N2/O2 ratio was adopted to infer other non-volcanic processes, such as air contamination and mixing with polluted surface waters. This methodology provides continuous sampling and thus, more information on short-term gas variations, since direct sampling is often impractical and hazardous. With our method, the geochemical monitoring benefits of the real-time analysis for high sampling rates that can be made comparable to the continuous measurements of geophysical networks. This allows a better understanding of hydrothermal features, particularly of chemical fluctuations occurring on the very short-term, and is fundamental to evaluate the evolution of unrest episodes at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, one of the most hazardous volcanic areas in the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..280..104W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..280..104W"><span>Possible coupling of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius as revealed by InSAR time series, correlation analysis and time dependent modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walter, T. R.; Shirzaei, M.; Manconi, A.; Solaro, G.; Pepe, A.; Manzo, M.; Sansosti, E.</p> <p>2014-06-01</p> <p>Volcanoes are often considered as isolated systems, however, evidences increase that adjacent volcanoes are directly coupled or may be closely related to remote triggers. At the Italian volcanoes <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius, as well as adjacent volcano-tectonic systems, all located in the Campania Volcanic Province with ~ 2 million inhabitants, a new analysis of satellite radar data reveals allied deformation activity. Here we show that during the 16-year records from 1992 to 2008, identified episodes of deformation have occurred in correlation. Albeit differences in the quantity of deformation, the sign, frequency and rate of pressure changes at reservoirs beneath <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius can be very similar, allowing to infer that pressure changes originating from a magmatic or tectonic source external to the shallow volcano magma plumbing systems is a likely cause. Such a fluid-mechanical coupling sheds light on the earlier episodes of correlated eruptions and deformations occurring during the historical roman times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610357S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610357S"><span>Operational short-term Probabilistic Volcanic Hazard Assessment of tephra fallout: an example from the 1982-1984 unrest at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sandri, Laura; Selva, Jacopo; Costa, Antonio; Macedonio, Giovanni; Marzocchi, Warner</p> <p>2014-05-01</p> <p> high eruption "scenario" respectively) and 700 possible vent positions within the CF Neapolitan Yellow Tuff <span class="hlt">caldera</span>. The probabilities related to eruption dynamics, and estimated by BET_EF, are based on the set up of the code obtained specifically for CF during a 6-years long elicitation project, and on the actual monitoring parameters measured during the unrest and published in the literature. We take advantage here of two novel improvements: (i) a time function to describe how the probability of eruption evolves within the time window defined for the forecast, and (ii) the production of hazard curves and their confidence levels, a tool that allows a complete description of PVHA and its uncertainties. The general goal of this study is to show what, and how, pieces of scientific knowledge can be operationally transferred to decision makers, and specifically how this could have been translated in practice during the 1982-84 <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> crisis, if scientists knew what we know today about this volcano.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031123','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031123"><span>Quantitative models for magma degassing and ground deformation (bradyseism) at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy: Implications for future eruptions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bodnar, R.J.; Cannatelli, C.; de Vivo, B.; Lima, A.; Belkin, H.E.; Milia, A.</p> <p>2007-01-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Phlegrean Fields) is an active volcanic center near Naples, Italy. Numerous eruptions have occurred here during the Quaternary, and repeated episodes of slow vertical ground movement (bradyseism) have been documented since Roman times. Here, we present a quantitative model that relates deformation episodes to magma degassing and fracturing at the brittle-ductile transition in a magmatic-hydrothermal enviromnent. The model is consistent with field and laboratory observations and predicts that uplift between 1982 and 1984 was associated with crystallization of ???0.83 km3 of H2O-saturated magma at 6 km depth. During crystallization, ???6.2 ?? 1010 kg of H2O and 7.5 ?? 108 kg of CO2, exsolved from the magma and generated ???7 ?? 1015 J of mechanical (P??V) energy to drive the observed uplift. For comparison, ???1017 J of thermal energy was released during the 18 May 1980 lateral blast at Mount St. Helens. ?? 2007 The Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PEPI..265...92C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PEPI..265...92C"><span>Inferences on the lithospheric structure of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> District (southern Italy) from seismic noise cross-correlation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Costanzo, M. R.; Nunziata, C.</p> <p>2017-04-01</p> <p>Lithospheric VS models are defined in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> District (southern Italy) through the non-linear inversion of the group velocity dispersion curves of fundamental-mode Rayleigh waves extracted from ambient noise cross-correlations between two receivers, and the regional group and phase velocities of the Italian cellular lithospheric model (1° × 1° cells). Four paths are investigated, of which one (ISCHIA-MIS) across two adjoining cells. The distribution of VS shows a pyroclastic covering with VS increasing from 0.3-0.7 km/s to 2.1 km/s. It rests on a lava or carbonate basement, about 5-6 km thick, with VS increasing from 2.1 km/s to 3.1 km/s at about 2 km of depth and rising to ∼0.6 km towards the island of Procida. A metamorphic layer is detected at an average depth of 7.7 km with VS of 3.8-3.9 km/s, about 5 km thick, overlying a low velocity layer (VS of 3.5 km/s) at about 11-12 km of depth. The VS model along the ISCHIA-MIS path, as average of the models obtained by combining local and regional dispersion data of the two adjoining cells, is well consistent with the other paths. The Moho discontinuity is retrieved at about 23 km of depth with VS of 4.2 km/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUSM.V23B..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUSM.V23B..04M"><span>First Volcanological-Probabilistic Pyroclastic Density Current and Fallout Hazard Map for <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Somma Vesuvius Volcanoes.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mastrolorenzo, G.; Pappalardo, L.; Troise, C.; Panizza, A.; de Natale, G.</p> <p>2005-05-01</p> <p>Integrated volcanological-probabilistic approaches has been used in order to simulate pyroclastic density currents and fallout and produce hazard maps for <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Somma Vesuvius areas. On the basis of the analyses of all types of pyroclastic flows, surges, secondary pyroclastic density currents and fallout events occurred in the volcanological history of the two volcanic areas and the evaluation of probability for each type of events, matrixs of input parameters for a numerical simulation have been performed. The multi-dimensional input matrixs include the main controlling parameters of the pyroclasts transport and deposition dispersion, as well as the set of possible eruptive vents used in the simulation program. Probabilistic hazard maps provide of each points of campanian area, the yearly probability to be interested by a given event with a given intensity and resulting demage. Probability of a few events in one thousand years are typical of most areas around the volcanoes whitin a range of ca 10 km, including Neaples. Results provide constrains for the emergency plans in Neapolitan area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B43A0223T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B43A0223T"><span>Degradation Pathways for Geogenic Volatile Organic Compounds (VOCs) in Soil Gases from the Solfatara Crater (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tassi, F.; Venturi, S.; Cabassi, J.; Capecchiacci, F.; Nisi, B., Sr.; Vaselli, O.</p> <p>2014-12-01</p> <p>The chemical composition of volatile organic compounds (VOCs) in soil gases from the Solfatara crater (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy) was analyzed to investigate the effects of biogeochemical processes occurring within the crater soil on gases discharged from the hydrothermal reservoir and released into the atmosphere through diffuse degassing. In this system, two fumarolic vents (namely Bocca Grande and Bocca Nuova) are the preferential pathways for hydrothermal fluid uprising. For our goal, the chemistry of VOCs discharged from these sites were compared to that of soil gases. Our results highlighted that C4-C9 alkanes, alkenes, S-bearing compounds and alkylated aromatics produced at depth were the most prone to degradation processes, such as oxidation-reduction and hydration-dehydration reactions, as well as to microbial activity. Secondary products, which were enriched in sites characterized by low soil gas fluxes, mostly consisted of aldheydes, ketons, esters, ethers, organic acids and, subordinately, alcohols. Benzene, phenol and hydrofluorocarbons (HCFCs) produced at depth were able to transit through the soil almost undisturbed, independently on the emission rate of diffuse degassing. The presence of cyclics was possibly related to an independent low-temperature VOC source, likely within sedimentary formations overlying the hydrothermal reservoir. Chlorofluorocarbons (CFCs) were possibly due to air contamination. This study demonstrated the strict control of biogeochemical processes on the behaviour of hydrothermal VOCs that, at least at a local scale, may have a significant impact on air quality. Laboratory experiments conducted at specific chemical-physical conditions and in presence of different microbial populations may provide useful information for the reconstruction of the degradation pathways controlling fate and behaviour of VOCs in the soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917390B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917390B"><span>Interferometric investigations with the S1 constellation: an application to the Vesuvius/<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic test site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borgstrom, Sven; Del Gaudio, Carlo; De Martino, Prospero; Siniscalchi, Valeria; Prats-Iraola, Pau; Nannini, Matteo; Yague-Martinez, Nestor; Pinheiro, Muriel; Kim, Jun-Su; Vecchioli, Francesco; Minati, Federico; Costantini, Mario; Foumelis, Michael; Desnos, Yves-Louis</p> <p>2017-04-01</p> <p>The contribution focuses on the current status of the ESA study entitled "INSARAP Sentinel-1 Constellation Study" and investigates the interferometric performance of the S1A/S1B units. In particular, we refer to the Vesuvius/<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Southern Italy) volcanic test site, where the continuous inflation (about 35 cm from 2011 to date) and the huge availability of ground-based geodetic data (continuous GPS - cGPS - leveling, tiltmetric, gravimetric, etc.) from the INGV-Osservatorio Vesuviano monitoring networks have allowed to get a clear deformation signal, besides the comparison between S1A/S1B and geodetic data. In this regard, the integration between InSAR and geodetic measurements is crucial for a continuous and extended monitoring of such an active volcanic area, as InSAR investigations allow to get an information on wide areas, whereas permanent networks (e.g., cGPS), allow to provide a continuous information complementing InSAR, which is limited by its revisiting time. Comparisons between S1 constellation data and geodetic measurements, with a particular focus on cGPS, will be presented, exploiting both LOS and inverted (E-W and vertical inversion) InSAR data starting from October, 2014. In addition, as a next step we are planning to model the deformation source of the area by exploiting the S1 time series results. Ultimately, very encouraging results suggest for a continuation of this activity also for the future, showing the great potential of S1 constellation data for monitoring active volcanic areas and, in general, to retrieve a very high quality deformation signal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ESRv...97...44L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ESRv...97...44L"><span>Thermodynamic model for uplift and deflation episodes (bradyseism) associated with magmatic-hydrothermal activity at the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lima, Annamaria; De Vivo, Benedetto; Spera, Frank J.; Bodnar, Robert J.; Milia, Alfonsa; Nunziata, Concettina; Belkin, Harvey E.; Cannatelli, Claudia</p> <p>2009-12-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (CF) is a large volcanic complex located west of the city of Naples, Italy. Repeated episodes of bradyseism (slow vertical ground movement) near the town of Pozzuoli have been documented since Roman times. Bradyseismic events are interpreted as the consequence of aqueous fluid exsolution during magma solidification on a slow timescale (10 3-10 4 yr) superimposed upon a shorter (1-10 yr) timescale for the episodic expulsion of fluid from a deep (~ 3-5 km) lithostatically-pressured low-permeability reservoir to an overlying hydrostatic reservoir. Cycles of inflation and deflation occur during short duration transient events when connectivity is established between deep and shallow hydrothermal reservoirs. The total seismic energy released (4 × 10 13 J) during the 1983-1984 bradyseismic crisis is consistent with the observed volume change (uplift) and consistent with the notion that seismic failure occurs in response to the shear stress release induced by volume change. Fluid transport and concomitant propagation of hydrofractures as fluid expands from lithostatic to hydrostatic pressure during decompression leads to ground surface displacement. Fluid decompression occurs along the fluid isenthalp (Joule-Thompson expansion) during transient periods of reservoir connectivity and leads to mineral precipitation. Each kilogram of fluid precipitates about 3 × 10 - 3 kg of silica along a typical decompression path along the isenthalp. Mineral precipitation modifies the permeability and acts to reseal connection paths thereby isolating lithostatic and hydrostatic reservoirs ending one bradyseism phase and beginning another. Crystallization and exsolution of the magmatic fluid generates ≈ 7 × 10 15 J of mechanical ( PΔ V) energy, and this is sufficient to accomplish the observed uplift at CF. Although magma emplacement is the ultimate origin of bradyseism, fresh recharge of magma is not a prerequisite. Instead, short to intermediate timescale phenomena</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.V43B3160L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V43B3160L"><span>Deployment of a novel field stable isotope analyzer: trials on fumaroles at Solfatara volcano, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leggett, G. A.; Weidmann, D.; Brownsword, R.; Caliro, S.</p> <p>2016-12-01</p> <p>Volcanic degassing is the primary mechanism by which carbon is transferred from Earth's interior to the atmosphere—making extensive monitoring of Earth's volcanoes essential to understanding the planet's total carbon budget. Determining the 13CO2/12CO2 ratio in emissions can reveal if the carbon was mantle or crust derived, allowing researchers to model carbon pathways among Earth's deep reservoirs. The Laser Isotope Ratiometer (LIR) is a new instrument specialized in measuring the ratio of stable isotopes of a given molecule. The current system has been developed and demonstrated for 13C:12C (δ13) analysis in CO2, with high precision (0.3 per mil in 10 seconds), in real time, and in a compact and robust package to allow deployment in-situ. The instrument underpinning architecture includes features such as drifts cancellation techniques and on-board calibration for autonomous operation and enhanced stability and accuracy. The LIR brings simplicity to stable isotope analysis, whether in the field or in a laboratory environment. The instrument's design originated as part of a European Space Agency programme to demonstrate the LIR for application in planetary landers. Overall the design offers compactness, robustness and precision without the need for a skilled operator or consumables and owing to a novel dual laser approach, the system offers far greater stability over a wide temperature range. Supported by an instrumentation grant from the Sloane Foundation Deep Carbon Observatory, a first field deployment of the LIR was conducted at the Solfatara volcano, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, to trial the in situ, real-time measurements of 13CO2/12CO2 ratios in fumaroles. The instrument operated very well in the field and proved to be extremely resilient to dirty samples. A systematic bias of -1 per mil was observed in comparison to the reference measurements made in the laboratory by isotopic ratio mass spectrometry, which was traced back to fractionation in long sampling</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSM.V31A..07A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSM.V31A..07A"><span>Collapse <span class="hlt">calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Diaz, G. J.; Marti, J.</p> <p>2007-05-01</p> <p>A collapse <span class="hlt">caldera</span> is a volcanic explosive structure that forms during the collapse of crustal blocks on top of a shallow magma chamber. During this collapse, a large volume of magma is evacuated, first explosively, in the form of pyroclastic fallouts and pyroclastic flows, and then effusively, as lava domes or flows after collapse. The result is a catastrophic explosive volcanic collapse that forms a depression that could end with different shapes, circular, oval, rectangular, or irregular. Three main types of collapse <span class="hlt">calderas</span> can be defined, 1) summit <span class="hlt">caldera</span>, 2) classic <span class="hlt">caldera</span>, and 3) graben <span class="hlt">caldera</span>. Summit <span class="hlt">calderas</span> are those formed at the top of large volcanoes and are related to relatively small-volume pyroclastic products that include plinian fallouts and ignimbrites, such as Crater Lake, Las Cañadas, and Somma-Vesuvio. Classic <span class="hlt">calderas</span> are semi-circular to irregular-shaped large structures, several km in diameter that are related to relatively large-volume pyroclastic products including pumice fallouts and widespread ignimbrites, such as Long-Valley, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, and Los Humeros. Graben <span class="hlt">calderas</span> are explosive volcano-tectonic collapse structures from which large-volume, ignimbrite-forming eruptions occurred through several vents along the graben walls and the intra-graben block faults causing the collapse of the graben or of a sector of the graben. The main products of graben <span class="hlt">calderas</span> are surge-deposits and large-volume widespread ignimbrite sheets. Pumice fallouts are practically absent. Examples include the Sierra Madre Occidental in Mexico, La Pacana (Andes), Catalan Pyrenees, and perhaps Scafell (United Kingdom). Any of the three <span class="hlt">caldera</span> types mentioned above could have collapsed in three different ways, 1) piston, when the collapse occurs as a single crustal block; 2) trap-door, when collapse occurs unevenly along one side while the opposite side remains with no collapse; 3) piece-meal, when collapse occurs as broken pieces of the crust on top of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JVGR..304..180P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JVGR..304..180P"><span>Native sulfur, sulfates and sulfides from the active <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe</p> <p>2015-10-01</p> <p>We investigated sulfur-bearing minerals from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the <span class="hlt">caldera</span> is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28801635','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28801635"><span>Thermally-assisted Magma Emplacement Explains Restless <span class="hlt">Calderas</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Amoruso, Antonella; Crescentini, Luca; D'Antonio, Massimo; Acocella, Valerio</p> <p>2017-08-11</p> <p>Many <span class="hlt">calderas</span> show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless <span class="hlt">calderas</span>, we interpret deformation data and build thermal models of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, Italy. <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> experienced at least 4 major unrest episodes in the last decades. Our results indicate that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust. Our thermal models show that this repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth ~3 ka before the last eruption. This may explain the persistence of the magmatic sources promoting the restless behaviour of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks. Our model of thermally-assisted unrest may have a wider applicability, possibly explaining also the dynamics of other restless <span class="hlt">calderas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JVGR...59..335P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JVGR...59..335P"><span>The dynamics of the Breccia Museo eruption (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy) and the significance of spatter clasts associated with lithic breccias</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perrotta, Annamaria; Scarpati, Claudio</p> <p>1994-02-01</p> <p>The Breccia Museo Member is a pyroclastic deposit produced during an eruptive event that occurred in the southwestern sector of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> about 20,000 years ago. Two depositional units divided by a co-ignimbrite ash-fall deposit have been recognized. Facies variations in the deposits resulted from the interaction between the flow and paleomorphology, from the relative abundance of the lithic and juvenile components supplied by the source, and from the variations of the flow regime. The Lower Depositional Unit is a pyroclastic flow deposit characterized by a thick, coarse valley facies laterally grading into a thin, layered and fine-grained overbank facies. These different facies are due to the interaction between a density-stratified flow and topography. The more basal, high-concentration part of the flow was deposited along the axis of the paleovalleys (valley facies), whereas the upper, low-concentration part was deposited on the slopes (overbank facies). Vertical variations of the structures observed in the deposits of the Lower Depositional Unit resulted from flow unsteadiness during emplacement and, hence, on the variations of the suspended load fallout from the low-concentration upper part of the flow to the high-concentration boundary layer. The Upper Depositional Unit, made up of the Breccia, Spatter and Upper Pumice Flow Units, consists of horizons of lithic breccias and coarse welded spatter which thicken into the valleys. They are closely related to a gas-pipe-rich ash and pumice flow deposit. The strongly fines-poor character of the breccias and spatter beds is due to a very rapid segregation of the dense and coarse clasts and to the high rates of gas ascent through the hindered-settling zone in the basal part of the flow. After deposition of the majority of the dense and coarse material, the subsequent high-density depositional system came to rest immediately, thus yielding a pyroclastic flow deposit that is closely associated with the breccia. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917637D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917637D"><span>2D and 3D high resolution seismic imaging of shallow Solfatara crater in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy): new insights on deep hydrothermal fluid circulation processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Landro, Grazia; Gammaldi, Sergio; Serlenga, Vincenzo; Amoroso, Ortensia; Russo, Guido; Festa, Gaetano; D'Auria, Luca; Bruno, Pier Paolo; Gresse, Marceau; Vandemeulebrouck, Jean; Zollo, Aldo</p> <p>2017-04-01</p> <p>Seismic tomography can be used to image the spatial variation of rock properties within complex geological media such as volcanoes. Solfatara is a volcano located within the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> still active <span class="hlt">caldera</span>, characterized by periodic episodes of extended, low-rate ground subsidence and uplift called bradyseism accompanied by intense seismic and geochemical activities. In particular, Solfatara is characterized by an impressive magnitude diffuse degassing, which underlines the relevance of fluid and heat transport at the crater and prompted further research to improve the understanding of the hydrothermal system feeding the surface phenomenon. In this line, an active seismic experiment, Repeated Induced Earthquake and Noise (RICEN) (EU Project MEDSUV), was carried out between September 2013 and November 2014 to provide time-varying high-resolution images of the structure of Solfatara. In this study we used the datasets provided by two different acquisition geometries: a) A 2D array cover an area of 90 x 115 m ^ 2 sampled by a regular grid of 240 vertical sensors deployed at the crater surface; b) two 1D orthogonal seismic arrays deployed along NE-SW and NW-SE directions crossing the 400 m crater surface. The arrays are sampled with a regular line of 240 receiver and 116 shots. We present 2D and 3D tomographic high-resolution P-wave velocity images obtained using two different tomographic methods adopting a multiscale strategy. The 3D image of the shallow (30-35 m) central part of Solfatara crater is performed through the iterative, linearized, tomographic inversion of the P-wave first arrival times. 2D P-wave velocity sections (60-70 m) are obtained using a non-linear travel-time tomography method based on the evaluation of a posteriori probability density with a Bayesian approach. The 3D retrieved images integrated with resistivity section and temperature and CO2 flux measurements , define the following characteristics: 1. A depth dependent P-wave velocity layer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5586S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5586S"><span>Continuous thermal infrared monitoring at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius (Italy) by automated data processing: an effective surveillance tool of active volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sansivero, Fabio; Vilardo, Giuseppe</p> <p>2014-05-01</p> <p>The INGV-Osservatorio Vesuviano Thermal Infrared Imagery Monitoring Network (TIIMNet) is made up of IR acquisition stations designed to continuously acquire IR scenes of diffuse degassing areas in the Neapolitan volcanic district. Every station consists of a RMS (Remote Monitoring Station) which manages the shooting functionalities of the IR camera and the connection to the surveillance Centre of INGV-Osservatorio Vesuviano in Naples. The first developed station was equipped with a NEC Thermo Tracer TS7302 IR camera (with 320x240 pixel FPA uncooled microbolometer); a newer one is equipped with a FLIR SC645 IR camera (with 640x480 pixel FPA uncooled microbolometer) and is supported by an in-house developed hardware which manages a fully real-time control of data acquisition and transfer procedures. As a whole, TIIMNet is composed of four permanent stations and three transportable ones. The first permanent NEC Station was installed at Vesuvius on July 2004 and dismissed on May 2007. A new permanent FLIR Station was set up on June 2011 and it acquires IR scenes from the inner SW slope of Vesuvius crater. In the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Pozzuoli, Italy) a permanent NEC Station was operative at Solfatara since September 2004 and it acquired scenes of the major fumaroles area located on the SE inner slope at the intersection of two active, SW-NE and NW-SE main faults. A permanent FLIR Station has been installed at Solfatara on June 2013 and takes IR shots of a significant thermal anomaly on the Northern inner slope of the crater. At Pisciarelli locality, on the Solfatara NE outer slope, a transportable NEC Station was set up on October 2006 and dismissed on September 2013. It was abreast of a permanent FLIR Station on March 2013. Both stations stored IR scenes of the outer eastern flank of the Solfatara tuff-cone characterized by heavy water vapor and CO2 emissions close to an active NW-SE fault. IR scenes are acquired every night by the TIIMNet stations and in real time</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AMT.....9.5721Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AMT.....9.5721Q"><span>2-D tomography of volcanic CO2 from scanning hard-target differential absorption lidar: the case of Solfatara, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Queißer, Manuel; Granieri, Domenico; Burton, Mike</p> <p>2016-11-01</p> <p>Solfatara is part of the active volcanic zone of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy), a densely populated urban area where ground uplift and increasing ground temperature are observed, connected with rising rates of CO2 emission. A major pathway of CO2 release at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> is diffuse soil degassing, and therefore quantifying diffuse CO2 emission rates is of vital interest. Conventional in situ probing of soil gas emissions with accumulation chambers is accurate over a small footprint but requires significant time and effort to cover large areas. An alternative approach is differential absorption lidar, which allows for a fast and spatially integrated measurement. Here, a portable hard-target differential absorption lidar has been used to acquire horizontal 1-D profiles of column-integrated CO2 concentration at the Solfatara crater. To capture heterogenic features in the CO2 distribution, a 2-D tomographic map of the CO2 distribution has been inverted from the 1-D profiles. The scan was performed one-sided, which is unfavorable for the inverse problem. Nonetheless, the result is in agreement with independent measurements and furthermore confirms an area of anomalous CO2 degassing along the eastern edge as well as the center of the Solfatara crater. The method may have important implications for measurements of degassing features that can only be accessed from limited angles, such as airborne sensing of volcanic plumes. CO2 fluxes retrieved from the 2-D map are comparable, but modestly higher than emission rates from previous studies, perhaps reflecting an increase in CO2 flux or a more integrated measurement or both.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995JVGR...68..325M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995JVGR...68..325M"><span>The eruption of the Breccia Museo (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy): Fractional crystallization processes in a shallow, zoned magma chamber and implications for the eruptive dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Melluso, Leone; Morra, Vincenzo; Perrotta, Annamaria; Scarpati, Claudio; Adabbo, Mariarosaria</p> <p>1995-11-01</p> <p>The Breccia Museo Member (BMM) was formed by an explosive eruption that occurred in the SW sector of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> about 20 ka ago. The eruptive sequence consists of the Lower Pumice Flow Unit and the overlying Upper Pumice Flow Unit with its associated lithic Breccia Unit. Interlayered with the Breccia Unit is a welded deposit that mainly consists of spatter clasts (Spatter Unit). The products of this eruption range in composition from trachytic to trachyphonolitic with K 2O decreasing from 9.5 to 7 wt.%; Na 2O correspondingly increases from 2.6 to 7.2 wt.% with increasing differentiation (Nb from 23 to 122 ppm). The phenocrysts are mostly sanidine (Or 88-63) with subordinate plagioclase (An 33-27), clinopyroxene (Ca 47Mg 44Fe 9 to Ca 46Mg 35Fe 19), biotite, titanomagnetite, and apatite. The observed major- and trace-element variations are fully consistent with about 80% fractional crystallization of a sanidine-dominated assemblage starting from the least differentiated trachytes. The compositions of the erupted products are compatible with the progressive tapping of a shallow magma chamber that was thermally and chemically zoned. The incompatible trace elements indicate a slightly different magma composition with respect to trachytes of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> mainland. The geochemical stratigraphy suggests that after an early eruptive phase during which the upper, most differentiated level of the magma chamber was tapped, the sudden collapse of the roof of the reservoir triggered drainage of the remaining magma, which ranged in composition from trachyte to trachyphonolite, and formed the Breccia Unit and the Upper Pumice Flow Unit. The strongly differentiated trachyphonolite composition of the spatter clasts also suggests that they likely originated from the uppermost part of the reservoir soon after the eruption of Lower Pumice Flow Unit and the collapse of the chamber roof. This is in agreement with the eruptive model proposed by Perrotta and Scarpati (1994).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V12B..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V12B..03C"><span>Probing the structure of a <span class="hlt">caldera</span> for geothermal assessment using enhanced passive seismic tomography. The example of the <span class="hlt">Campi</span> Flregrei (Italy).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Calo, M.; Tramelli, A.; Troise, C.; de Natale, G.</p> <p>2015-12-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (southern Italy) is one of the most studied <span class="hlt">calderas</span> of the world due to its geothermal potential that was exploited since Romans' age, and its eruption and seismic risk, affecting a densely populated region. The <span class="hlt">caldera</span> is marked by strong vertical deformations of the soil called bradyseisms, which are often accompanied by seismic crises. In particular the bradyseismic crises of 1982-84 are remembered for the large number of earthquakes that exceeded 16000 events recorded. Seismicity has been used to model the distribution of the elastic parameters with the aim to study the volcano behavior. However, till now seismic velocity models, calculated with standard tomography, failed in resolving small structures (<1.5-2km) located also at shallow depth, which could be responsible of small eruption as the last one that originated the Monte Nuovo monogenic cone in 1538. Here we show Vp and Vp/Vs models carried out by applying an enhanced seismic tomography that uses the Double Difference method (DD, Zhang and Thurber, 2003) complemented with the Weighted Average Model post-processing (WAM, Calò et al., 2009, Calò et al., 2011, 2013). The 3D models obtained with this procedure benefit of the high resolving power due to DD method, which uses both absolute and differential data, and of the improved reliability offered by WAM, which allows to overcome the drawbacks of the standard inversion methods. Our approach allowed to image structures with linear dimension of 0.5-1.2km, resulting in an improvement of the resolving power at least two times of the other published models (e.g. Priolo et al., 2012). Results show small bodies of high Vp and Vp/Vs at shallow depth (2.5-3.5 km) that could be associated either with magmatic intrusions or fluid saturated rocks, probably responsible of unrest episodes. At shallower depth (0.5-2.0 km), the Vp/Vs model is able to discern between water- and gas- bearing regions giving insight on the assessment of the potential of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH21B1514S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH21B1514S"><span>Application of laser scanning and opto-electronic devices for monitoring cliff instability in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> coastal area: the Coroglio case study ( Napoli, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Somma, R.; Caputo, T.; Esposito, G.; Marino, E.; Matano, F.; Carlino, S.; Iuliano, S.; Sacchi, M.; Troise, C.; De Natale, G.</p> <p>2013-12-01</p> <p>This study introduces a Terrestrial Laser Scanning (TLS) application for the landslides monitoring and its experiment in Gulf of Pozzuoli coastal area (Italy). This area is a part of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic district, one of the major volcanic risk zones of the world, with more than 300.000 people and a lot of infrastructures concentrated within it. The cliffs consist of very erodible volcanoclastic lithologies as same as tuffs and ignimbrites, affected by the erosive action of both sea and meteorological agents, very high erosion rate. Furthermore, in this area the bradyseismic phenomenon occurred too, producing differential displacement and fracturing. The Coroglio test site was chosen taking into account cliff's geological and geomorphological properties, as well as aspect, fractures, lithology, and elements at risk located upslope or downslope: The Coroglio site is characterized by lithified upper member of the NYT with stratified, wavy-to-planar alternations of coarse-grained, disorganized, matrix-supported layers, thinly-laminated discontinuous beds and massive, even fine ash layers. The accuracy of the technique used reaches a detailed level in landslide monitoring which allows this methodology to be complementary to the monitoring by setup a geodetic deformation monitoring network. With this aim we have firstly reconstructed a 3D model of the investigated cliff with the use of dedicated softwares and successively analyzed the main lithological, structural and geomorphologic elements related to cliff instability processes. What is possible to confirm after this first study, can be here resumed: (1) These tests were designed to set-up landslide monitoring in highly urbanised areas such as the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>; they are very important sites with a well-established road network, which can be affected by landslide phenomena as occurred in the past causing either traffic interruption and damage to infrastructures insisting along the landslides fronts. (2) In the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V11C2068A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V11C2068A"><span><span class="hlt">Caldera</span> types and collapse styles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Diaz, G. J.</p> <p>2008-12-01</p> <p>Three main types of collapse <span class="hlt">calderas</span> can be defined, 1) summit <span class="hlt">caldera</span>, 2) classic <span class="hlt">caldera</span>, and 3) graben <span class="hlt">caldera</span>. Summit <span class="hlt">calderas</span> are those formed at the top of large volcanoes and are related to relatively small- volume pyroclastic products that include plinian fallouts and ignimbrites, such as Crater Lake, Las Cañadas, and Somma-Vesuvio. Classic <span class="hlt">calderas</span> are semi-circular to irregular-shaped large structures, several km in diameter that are related to relatively large-volume pyroclastic products including pumice fallouts and widespread ignimbrites, such as Long-Valley, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, and Los Humeros. Graben <span class="hlt">calderas</span> are explosive volcano-tectonic collapse structures from which large-volume, ignimbrite-forming eruptions occurred through several vents along the graben walls and the intra-graben block faults causing the collapse of the graben or of a sector of the graben. The main products of graben <span class="hlt">calderas</span> are surge-deposits and large-volume widespread ignimbrite sheets. Pumice fallouts are practically absent. Examples include the Sierra Madre Occidental in Mexico, La Pacana (Andes), Catalan Pyrenees, and perhaps Scafell (United Kingdom). Any of the three <span class="hlt">caldera</span> types mentioned above could have collapsed at least in three different ways, 1) piston, when the collapse occurs as a single crustal block; 2) trap-door, when collapse occurs unevenly along one side while the opposite side remains with no collapse; 3) piece-meal, when collapse occurs as broken pieces of the crust on top of the magma chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8026C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8026C"><span>Modelling of InSAR (LOS) changes by means of 3D extended pressured bodies with free geometry. Application to <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Camacho, Antonio. G.; Fernandez, Jose; Gonzalez, Pablo J.; Berrino, Giovanna</p> <p>2010-05-01</p> <p>InSAR measures can provide information about changes in distance between the ground and the satellite in radar line-of-sight (LOS) direction. Sometimes, as in the case of volcanic activity, the corresponding ground deformations can be modeled by means of pressure and/or mass sources. Usually, point sources and regular prolate or oblate bodies are used as source geometry for deformation. In this communication, we show a new method for non-linear inversion of position and gravity changes as produced by extended bodies with a free geometry. Their structures are described as aggregation of elemental sources with anomalous density and pressure, and they are modeled to fit the whole data and to keep some regularity conditions. A growth process permits to build general geometrical configurations. The method is tested by application to data of gravity and InSAR (LOS data for ascending and descending orbits) for the volcanic area of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy). Results are drawn with respect a structural gravimetric model and compared with previous models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120..812V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120..812V"><span>Long-term TIR imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment: A case study in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vilardo, G.; Sansivero, F.; Chiodini, G.</p> <p>2015-02-01</p> <p>Different procedures were used to analyze a comprehensive time series of nighttime thermal infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal changes in the ground-surface thermal features of an area affected by diffuse degassing. Long-term infrared time series images were processed without taking into account atmospheric conditions and emissivity estimations. The data obtained were compared with the trends of independent geophysical and geochemical parameters, which suggested that long-term temporal variations of the surface maximum temperatures were governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow hydrothermal system are likely to control the short-period thermal oscillations that overlie the long-term thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state, the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal sites obtained by long-term infrared monitoring can provide useful information toward refining physical and conceptual models, as well as improving surveillance of active volcanoes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987BVol...49..381T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987BVol...49..381T"><span>The determination of deep temperatures by means of the CO-CO2-H2-H2O geothermometer: an example using fumaroles in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tedesco, D.; Sabroux, J. C.</p> <p>1987-02-01</p> <p>Chromatographic analyses of fumarolic gases, collected in sampling bottles containing an alkaline solution, have been carried out using a thermal conductivity detector and a flame ionization detector, after catalytic conversion of CO and CH4. The latter method enables the concentration of carbon monoxide to be measured with sufficient accuracy for use in a CO-CO2-H2-H2O geothermometer. Application of this geothermometer to fumaroles in the crater of Solfatara in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, indicates that they are fed from a steam reservoir at 250±15 °C and at 10-36±2atm of oxygen. On the other hand, the CH4-CO2-H2-H2O geothermobarometer seems to re-equilibrate at superficial temperatures and cannot be used for infering thermodynamic conditions at depth. Regular sampling of these fumaroles together with a geothermometric interpretation of the gas analyses provides a means of monitoring, with comparative accuracy, the chemical and thermal evolution of the hydrothermal reservoir below the Solfatara crater. Such monitoring would probably detect an increase in temperature at depth and the injection of magmatic gas into the reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1713169S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713169S"><span>Automatized near-real-time short-term Probabilistic Volcanic Hazard Assessment of tephra dispersion before eruptions: BET_VHst for Vesuvius and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> during recent exercises</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Selva, Jacopo; Costa, Antonio; Sandri, Laura; Rouwet, Dmtri; Tonini, Roberto; Macedonio, Giovanni; Marzocchi, Warner</p> <p>2015-04-01</p> <p>Probabilistic Volcanic Hazard Assessment (PVHA) represents the most complete scientific contribution for planning rational strategies aimed at mitigating the risk posed by volcanic activity at different time scales. The definition of the space-time window for PVHA is related to the kind of risk mitigation actions that are under consideration. Short temporal intervals (days to weeks) are important for short-term risk mitigation actions like the evacuation of a volcanic area. During volcanic unrest episodes or eruptions, it is of primary importance to produce short-term tephra fallout forecast, and frequently update it to account for the rapidly evolving situation. This information is obviously crucial for crisis management, since tephra may heavily affect building stability, public health, transportations and evacuation routes (airports, trains, road traffic) and lifelines (electric power supply). In this study, we propose a methodology named BET_VHst (Selva et al. 2014) for short-term PVHA of volcanic tephra dispersal based on automatic interpretation of measures from the monitoring system and physical models of tephra dispersal from all possible vent positions and eruptive sizes based on frequently updated meteorological forecasts. The large uncertainty at all the steps required for the analysis, both aleatory and epistemic, is treated by means of Bayesian inference and statistical mixing of long- and short-term analyses. The BET_VHst model is here presented through its implementation during two exercises organized for volcanoes in the Neapolitan area: MESIMEX for Mt. Vesuvius, and VUELCO for <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. References Selva J., Costa A., Sandri L., Macedonio G., Marzocchi W. (2014) Probabilistic short-term volcanic hazard in phases of unrest: a case study for tephra fallout, J. Geophys. Res., 119, doi: 10.1002/2014JB011252</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JVGR..233....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JVGR..233....1B"><span>Influence of volcanic gases on the epidermis of Pinus halepensis Mill. in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy: A possible tool for detecting volcanism in present and past floras</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bartiromo, Antonello; Guignard, Gaëtan; Lumaga, Maria Rosaria Barone; Barattolo, Filippo; Chiodini, Giovanni; Avino, Rosario; Guerriero, Giulia; Barale, Georges</p> <p>2012-07-01</p> <p>Cuticle micromorphology together with epidermal and epistomatal wax, in both current- and first-year-old needles of conifer Pinus halepensis (Aleppo pine) trees growing under volcanic gas fumigation was analysed in Pisciarelli area, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy. As a control, current- and first-year-old needles growing far from volcanic gas emission were also sampled. Using a multidisciplinary approach with SEM, TEM and X-ray, volcanic gases were shown to cause degradation on epicuticular and epistomatal waxes. Significant statistical variations of ultrastructural components of the cuticle, with 30 measurements, including total thickness of the cuticle, and details and proportions of all different layers, and use of confidence interval, revealed a high degree of sensitivity of Aleppo pine to this extreme environment. In the present study, non-significant thickness variations of the cell wall plus cuticle among current- and first-year-old needles of both fumigated and non fumigated trees have been found. However, at the ultrastructural level, significant variations in cell wall and total cuticle thickness, especially within the three zones of B1 fibrillar layer, revealed different equilibria for each of the four types of material. Using energy dispersive X-ray microanalysis, no sulphur was found in either cuticle or epidermal cells, but the presence of H2S in the fumarole gas is suspected to cause indirect and/or direct cuticle alterations of wax structure. Ultrastructural characters of plant cuticles related to emission of volcanic gases during the geological past are also discussed. Among these considerations, an identification key enabling distinction between non fumigated and fumigated materials with 9 characters, provides a good tool detecting the influence of volcanism for extant and fossil plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610499T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610499T"><span>The effect of the sea on hazard assessment for tephra fallout at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>: a preliminary approach through the use of pyPHaz, an open tool to analyze and visualize probabilistic hazards</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tonini, Roberto; Sandri, Laura; Costa, Antonio; Selva, Jacopo</p> <p>2014-05-01</p> <p><span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (CF) is a large volcanic field located west of the Gulf of Naples, characterized by a wide and almost circular <span class="hlt">caldera</span> which is partially submerged beneath the Gulf of Pozzuoli. It is known that the magma-water interaction is a key element to determine the character of submarine eruptions and their impact on the surrounding areas, but this phenomenon is still not well understood and it is rarely considered in hazard assessment. The aim of the present work is to present a preliminary study of the effect of the sea on the tephra fall hazard from CF on the municipality of Naples, by introducing a variability in the probability of tephra production according to the eruptive scale (defined on the basis of the erupted volume) and the depth of the opening submerged vents. Four different Probabilistic Volcanic Hazard Assessment (PVHA) models have been defined through the application of the model BET_VH at CF, by accounting for different modeling procedures and assumptions for the submerged part of the <span class="hlt">caldera</span>. In particular, we take into account: 1) the effect of the sea as null, i.e. as if the water were not present; 2) the effect of the sea as a cap that totally blocks the explosivity of eruptions and consequently the tephra production; 3) an ensemble model between the two models described at the previous points 1) and 2); 4) a variable probability of tephra production depending on the depth of the submerged vent. The PVHA models are then input to pyPHaz, a tool developed and designed at INGV to visualize, analyze and merge into ensemble models PVHA's results and, potentially, any other kind of probabilistic hazard assessment, both natural and anthropic, in order to evaluate the importance of considering a variability among subaerial and submerged vents on tephra fallout hazard from CF in Naples. The analysis is preliminary and does not pretend to be exhaustive, but on one hand it represents a starting point for future works; on the other hand, it is a good</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRB..114.3213M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRB..114.3213M"><span>Principles of volcanic risk metrics: Theory and the case study of Mount Vesuvius and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marzocchi, Warner; Woo, Gordon</p> <p>2009-03-01</p> <p>Despite volcanic risk having been defined quantitatively more than 30 years ago, this risk has been managed without being effectively measured. The recent substantial progress in quantifying eruption probability paves the way for a new era of rational science-based volcano risk management, based on what may be termed "volcanic risk metrics" (VRM). In this paper, we propose the basic principles of VRM, based on coupling probabilistic volcanic hazard assessment and eruption forecasting with cost-benefit analysis. The VRM strategy has the potential to rationalize decision making across a broad spectrum of volcanological questions. When should the call for evacuation be made? What early preparations should be made for a volcano crisis? Is it worthwhile waiting longer? What areas should be covered by an emergency plan? During unrest, what areas of a large volcanic field or <span class="hlt">caldera</span> should be evacuated, and when? The VRM strategy has the paramount advantage of providing a set of quantitative and transparent rules that can be established well in advance of a crisis, optimizing and clarifying decision-making procedures. It enables volcanologists to apply all their scientific knowledge and observational information to assist authorities in quantifying the positive and negative risk implications of any decision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..289...26B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..289...26B"><span>First combined flux chamber survey of mercury and CO2 emissions from soil diffuse degassing at Solfatara of Pozzuoli crater, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy): Mapping and quantification of gas release</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bagnato, E.; Barra, M.; Cardellini, C.; Chiodini, G.; Parello, F.; Sprovieri, M.</p> <p>2014-12-01</p> <p>There have been limited studies to date targeting gaseous elemental mercury (GEM) flux from soil emission in enriched volcanic substrates and its relation with CO2 release and tectonic structures. In order to evaluate and understand the processes of soil-air exchanges involved at Solfatara of Pozzuoli volcano, the most active zone of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy), an intensive field measurement survey has been achieved in September 2013 by using high-time resolution techniques. Soil-air exchange fluxes of GEM and CO2 have been measured simultaneously at 116 points, widely distributed within the crater. Quantification of gas flux has been assessed by using field accumulation chamber method in conjunction with a Lumex®-RA 915 + portable mercury vapor analyzer and a LICOR for CO2 determination, respectively. The spatial distribution of GEM and CO2 emissions correlated quite closely with the hydrothermal and geological features of the studied area. The highest GEM fluxes (from 4.04 to 5.9 × 10- 5 g m- 2 d- 1) were encountered close to the southern part of the crater interested by an intense fumarolic activity and along the SE-SW tectonic fracture (1.26 × 10- 6-6.91 × 10- 5 g GEM m- 2 d- 1). Conversely, the lowest values have been detected all along the western rim of the crater, characterized by a weak gas flux and a lush vegetation on a very sealed clay soil, which likely inhibited mercury emission (range: 1.5 × 10- 7-7.18 × 10- 6 g GEM m- 2 d- 1). Results indicate that the GEM exchange between soil and air inside the Solfatara crater is about 2-3 orders of magnitude stronger than that in the background areas (10- 8-10- 7 g m- 2 d- 1). CO2 soil diffuse degassing exhibited an analogous spatial pattern to the GEM fluxes, with emission rates ranging from about 15 to ~ 20,000 g CO2 m- 2 d- 1, from the outermost western zones to the south-eastern sector of the crater. The observed significant correlation between GEM and CO2 suggested that in volcanic system GEM</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1211010M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1211010M"><span>Viscosity of <span class="hlt">Campi</span> Flregrei (Italy) magmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Misiti, Valeria; Vetere, Francesco; Scarlato, Piergiorgio; Behrens, Harald; Mangiacapra, Annarita; Freda, Carmela</p> <p>2010-05-01</p> <p> ν is the viscosity in Pa×s, T the temperature in K, and w is the water content in wt%; a, b, c, d, e, g are the Vogel-Fulcher-Tamman parameters. Each of the two compositions shows its own VTF parameters. Following this equation we can now calculate viscosity values for the two compositions under the condition inferred for <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> magma chambers, i.e., water content from 0.3 to 3 wt%, T=1393K (Mangiacapra et al., 2008). For melt with 0.3 wt% water content we obtain viscosity values (ν in Pas) of 102.68and 102.24 for shoshonite and latite, respectively. At higher water contents of about 3 wt% the viscosity difference decreases to 101.71 (shoshonite) and 101.51 (latite). One important application of these data is the estimate of flow regime and magma rising velocity from deep to shallow reservoirs. Given the inferred magma water contents (0.3 and 3 wt%), temperature (1393K) and depth of deep and shallow reservoirs (9 and 4 km, respectively, Mangiacapra et al., 2008) and assuming a 2 m dyke wide, we have calculated (Lister and Kerry, 1991) a rising time from deep to shallow reservoir in the order of few minutes, 4.4 and 5.9 for a shoshonitic magma with 3 and 0.3 wt% water content, respectively. The same order of magnitude (4.1 and 5.2) has been obtained for latitic magma with similar amount of water. Lister and Kerry (1991) Fluid mechanical models of cracks propagation and their application to magmatic transport and dyke. Journal of Geophysical Research 96, 10049-10077. Mangiacapra A., Moretti, R., Rutherford L., Civetta L., Orsi G., Papale P. (2008) The deep magmatic system of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy). Geophysical Research Letters 35, L21304.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BVol...78...72A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BVol...78...72A"><span>Constraining pre-eruptive magma conditions and unrest timescales during the Monte Nuovo eruption (1538 ad; <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy): integrating textural and CSD results from experimental and natural trachy-phonolites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arzilli, Fabio; Piochi, Monica; Mormone, Angela; Agostini, Claudia; Carroll, Michael R.</p> <p>2016-10-01</p> <p>We present crystallization experiments representing a broad range of growth conditions of alkali feldspar and sodalite in a trachy-phonolite magma composition during later stages of evolution. Our results include (i) textural data and mineral assemblages of synthetic samples; (ii) feldspar nucleation kinetics and growth rate estimates; and (iii) textural data, mineral abundances, and crystal size distribution measurements on samples representative of the Monte Nuovo eruption (1538 ad), the last eruption of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy. Experiments reproduced the texture and feldspar content of natural products indicating that kinetic data can provide insights into processes within the volcanic system shortly before and during this small-magnitude eruption and, particularly, about magma ascent timescale. We suggest that the groundmass crystallization of Monte Nuovo magma started between 4 and 7 km depth (˜100-200 MPa) at a temperature between 825 and 840 °C (close to the liquidus of alkali feldspar). The crystallization kinetics of alkali feldspar and the absence of sodalite in most of the natural samples indicate that magma ascent rate increased in the shallow part of the conduit from about 3 km depth to the quenching level (possibly fragmentation point; ˜30 MPa), during the first phases of the eruption. The crystallization time of the magma requires that it ascended from pre-eruptive storage to the quenching level in several hours to a few days. We also observe that a small decrease in pressure can induce a dramatic increase in crystallinity, with associated rheological changes, leading to changes in the eruption style, and such changes could occur on timescales of hours to several days. The products from the later phases of the Monte Nuovo eruption are more crystalline and contain sodalite in response to the decrease in magma ascent rate, which in turn allowed for more degassing during ascent, resulting in more time spent at very shallow depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70178394','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70178394"><span>Magmatic-hydrothermal fluid interaction and mineralization in alkali-syenite nodules from the Breccia Museo pyroclastic deposit, Naples, Italy: Chapter 7 in Volcanism in the Campania Plain — Vesuvius, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Ignimbrites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fedele, Luca; Tarzia, Maurizio; Belkin, Harvey E.; De Vivo, Benedetto; Lima, Annamaria; Lowenstern, Jacob</p> <p>2007-01-01</p> <p>The Breccia Museo, a pyroclastic flow that crops out in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic complex (Naples, Italy), contains alkali-syenite (trachyte) nodules with enrichment in Cl and incompatible elements (e.g., U, Zr, Th, and rare-earth elements). Zircon was dated at ≈52 ka, by U-Th isotope systematics using a SHRIMP. Scanning electron microscope and electron microprobe analysis of the constituent phases have documented the mineralogical and textural evolution of the nodules of feldspar and mafic accumulations on the magma chamber margins. Detailed electron microprobe data are given for alkali and plagioclase feldspar, salite to ferrosalite clinopyroxene, pargasite, ferrogargasite, magnesio-hastingsite hornblende amphibole, biotite mica, Cl-rich scapolite, and a member (probable davyne-type) of the cancrinite group. Detailed whole rock, major and minor element data are also presented for selected nodules. A wide variety of common and uncommon accessory minerals were identified such as zircon, baddeleyite, zirconolite, pollucite, sodalite, titanite, monazite, cheralite, apatite, titanomagnetite and its alteration products, scheelite, ferberite, uraninite/thorianite, uranpyrochlore, thorite, pyrite, chalcopyrite, and galena. Scanning electron microscope analysis of opened fluid inclusions identified halite, sylvite, anhydrite, tungstates, carbonates, silicates, sulfides, and phosphates; most are probably daughter minerals. Microthermometric determinations on secondary fluid inclusions hosted by alkali feldspar define a temperature regime dominated by hypersaline aqueous fluids. Fluid-inclusion temperature data and mineral-pair geothermometers for coexisting feldspars and hornblende and plagioclase were used to construct a pressure-temperature scenario for the development and evolution of the nodules. We have compared the environment of porphyry copper formation and the petrogenetic environment constructed for the studied nodules. The suite of ore minerals observed in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.3018T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.3018T"><span>3D Imaging of Brittle/Ductile transition of the crust beneath the resurgent <span class="hlt">calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tizzani, P.; Castaldo, R.; Pepe, S.; Solaro, G.</p> <p>2012-04-01</p> <p>Rheology is a crucial factor to understand the mechanical behaviour and evolution of the crust in young and tectonically active belts. The aim of this paper is to investigate the rheological properties of the crust beneath resurgent <span class="hlt">calderas</span> as Long Valley <span class="hlt">caldera</span> (California USA) and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Southern Italy). Through the rheological proprieties of the <span class="hlt">calderas</span> area, we highlight the driving process that determine the cut off of the local seismicity [K. Ito, 1993]. In this context, we consider the thermal proprieties and mechanical heterogeneity of the crust in order to develop a 3D conductive time dependent thermal model of the upper crust beneath the two <span class="hlt">calderas</span>. More specifically we integrate geophysical information (gravimetric, seismic and boreholes data) available for the considered area in FEM environment [Manconi A. et al., 2010]. We performed a numerical solution of Fourier equation to carry out an advance optimization of the real measured data. We produce a set of forward models and propose, in order to analyse and solve the statistical problem, the Monte Carlo optimization procedures as Genetic Algorithm [Manconi A. et al., 2009]. In particular we search for the heat production, the volume source distribution and the surface emissivity parameters that providing the best-fit of the geothermal profiles data measured at boreholes, by solving the non stationary heat flow equation (Campanian Ignimbrite eruption about 40 kyr for <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> and Bishop tuff eruption about 700 kyr for Long Valley <span class="hlt">caldera</span>). The performed thermal fields allow us to obtain the rheological stratification of the crust beneath two resurgent <span class="hlt">calderas</span>; the models suggest that the uprising of a ductile layer which connects the upper mantle to the volcanic feeding system could determine the stress conditions that controlled the distribution of seismicity. In fact, the computed 3D imaging of Brittle/Ductile transition well agrees with the seismic hypocentral distribution</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.8825E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.8825E"><span>Volcano hazards implications of rhyolitic melt or magma at shallow depth under Krafla <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eichelberger, John; Papale, Paolo; Sigmundsson, Freysteinn</p> <p>2014-05-01</p> <p>. Results should be directly applicable to densely populated <span class="hlt">Campi</span> Felgrei, where complementary ICDP drilling is not targeted at a magmatic source, but may reveal similar structures. Solidified magma bodies that did not erupt have been imaged seismically at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> at depths of even less than 2 km. Modeling of convection and mixing processes inside shallow chambers show that such bodies may not be visible during emplacement from seismicity and deformation, and would instead "point" to larger depths even if most of the dynamics are much shallower.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22297973','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22297973"><span>Decadal to monthly timescales of magma transfer and reservoir growth at a <span class="hlt">caldera</span> volcano.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Druitt, T H; Costa, F; Deloule, E; Dungan, M; Scaillet, B</p> <p>2012-02-01</p> <p><span class="hlt">Caldera</span>-forming volcanic eruptions are low-frequency, high-impact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at <span class="hlt">calderas</span> such as Yellowstone, USA, and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' <span class="hlt">caldera</span>-forming eruption of Santorini volcano, Greece, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption. Despite the large volume of erupted magma (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicic magma batches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, <span class="hlt">caldera</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SolE....7..557C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SolE....7..557C"><span>Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coco, A.; Gottsmann, J.; Whitaker, F.; Rust, A.; Currenti, G.; Jasim, A.; Bunney, S.</p> <p>2016-04-01</p> <p>Ground deformation and gravity changes in restless <span class="hlt">calderas</span> during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a <span class="hlt">caldera</span> setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.<p class="p">Informed by constraints available for the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1387C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1387C"><span>Preliminary report, between seismic swarms, the constant cycles of inflation/ deflation in some volcanic <span class="hlt">calderas</span> in the world and the minimum and/or solar maximum years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Casati, Michele</p> <p>2014-05-01</p> <p>The global communication network and GPS satellites have enabled us to monitor for more than a decade, some of the more sensitive, well-known and highly urbanized volcanic areas around the world. The possibility of electromagnetic coupling between the dynamics of the Earth-Sun and major geophysical events is a topic of research. However the majority of researchers are orienting their research in one direction. They are attempting to demonstrate a significant EM coupling between the solar dynamics and terrestrial seismicity ignoring a possible relationship between solar dynamics and the dynamics inherent in volcanic <span class="hlt">calderas</span>. The scientific references are scarce, however, a study conducted by the Vesuvius Observatory of Naples, notes that the seismic activity on the volcano is closely related to changes in solar activity and the Earth's magnetic field. We decided to extend the study to many other volcanic <span class="hlt">calderas</span> in the world in order to generalise the relationship between solar activity and <span class="hlt">caldera</span> activity and/or deformation of the ground. The list of Northern Hemisphere volcanoes examined is as follows: Long Valley, Yellowstone, Three sisters, Kilauea Hawaii, Axial seamount (United States); Augustine ( Alaska), Sakurajima (Japan); Hammarinn, Krisuvik; Askja (Iceland) and <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (Italy). We note that the deformation of volcanoes recorded in GPS logs varies in long, slow geodynamic processes related to the two well-known time periods within the eleven-year cycle of solar magnetic activity: the solar minimum and maximum. We find that the years of minimum (maximum), are coincident with the years in which transition between a phase of deflation (inflation) occurs. Additionally, the seismicity recorded in such areas reaches its peak in the years of solar minimum or maximum. However, the total number and magnitude of seismic events is greater during deep solar minima, than maxima, evidenced by increased seismic activity occurring between 2006 and 2010. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.3397D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3397D"><span>The ICDP-CFDDP Project: Understanding <span class="hlt">caldera</span> dynamics and mitigating the extreme risk of the most urbanised volcano in the World</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Natale, Giuseppe; Troise, Claudia; Carlino, Stefano; Somma, Renato; Piochi, Monica; Di Vito, Mauro; Isaia, Roberto; De Vita, Sandro; Sacchi, Marco; Josè Jurado, Maria; Wiersberg, Thomas; Kueck, Jochem; Molisso, Flavia; Erzinger, Joerge; Kilburn, Christopher R. J.; Gudmundsson, Agust; Burg, Jean Pierre; Zappone, Alba; Hill, David P.</p> <p>2013-04-01</p> <p>The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> Deep Drilling Project (CFDDP) entered the operative phase during the second half of 2012, with the pilot hole drilling. The Project was initiated to address two kinds of problems: 1) purely volcanological, to understand in detail the dynamics of the most explosive and yet mostly unknown volcanism on the Earth with the potential to generate global catastrophes, and 2) to mitigate the highest volcanic risk in the World, namely the one associated with the metropolitan area of Naples where more than 3,000,000 people are exposed to extreme risk. The CFDDP Project offers the only direct means to understand the physics driving the on-going ground uplift affecting the area since at least six centuries, through in situ and laboratory measurements of rock rheology and permeability. In particular, direct investigation at depth by drilling is essential for understanding the extent that shallow magma intrusion is involved in the uplift of 15 to 20 m accumulated over the last centuries. Such a high cumulative uplift corresponds to 1-10 km3 of new magma intruded into the system, depending on details of the model used. Such an erupted volume should be conservatively assumed as the worst scenario for a future eruption. This corresponds to a massive eruption, largest than any other one after the <span class="hlt">caldera</span>-forming Yellow Tuff eruption of 15,000 y BP and not much smaller than that, which would anyway require evacuation of some millions people. An alternative possibility is that the cumulative uplift is mostly due to shallow geothermal perturbations as described in several recent publications. Both possibilities, each with widely differing hazard implications, rely strongly on as yet poorly known conditions at depth beneath the <span class="hlt">caldera</span>. It is thus crucial to discriminate between these two opposing possibilities in order to clarify the worst scenario for a future eruption and to provide an invaluable tool for civil defence at this densely populated area. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ESRv...69....1C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ESRv...69....1C"><span><span class="hlt">Calderas</span> and <span class="hlt">caldera</span> structures: a review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole, J. W.; Milner, D. M.; Spinks, K. D.</p> <p>2005-02-01</p> <p><span class="hlt">Calderas</span> are important features in all volcanic environments and are commonly the sites of geothermal activity and mineralisation. Yet, it is only in the last 25 years that a thorough three-dimensional study of <span class="hlt">calderas</span> has been carried out, utilising studies of eroded <span class="hlt">calderas</span>, geophysical analysis of their structures and analogue modelling of <span class="hlt">caldera</span> formation. As more data has become available on <span class="hlt">calderas</span>, their individuality has become apparent. A distinction between '<span class="hlt">caldera</span>', '<span class="hlt">caldera</span> complex', 'cauldron', and 'ring structure' is necessary, and new definitions are given in this paper. Descriptions of <span class="hlt">calderas</span>, based on dominant composition of eruptives (basaltic, peralkaline, andesitic-dacitic, rhyolitic) can be used, and characteristics of each broad group are given. Styles of eruption may be effusive or explosive, with the former dominant in basaltic <span class="hlt">calderas</span>, and the latter dominant in andesitic-dacitic, rhyolitic and peralkaline <span class="hlt">calderas</span>. Four 'end-member' collapse styles occur—plate or piston, piecemeal, trapdoor, and downsag—but many <span class="hlt">calderas</span> have multiple styles. Features of so-called 'funnel' and 'chaotic' <span class="hlt">calderas</span> proposed in the literature can be explained by other collapse styles and the terms are considered unnecessary. Ground deformation comprises subsidence or collapse (essential characteristics of a <span class="hlt">caldera</span>) and uplifting/doming and fracturing due to tumescence and/or resurgence (frequent, but not essential). Collapse may occur on pre-existing structures, such as regional faults or on faults created during the <span class="hlt">caldera</span> formation, and the shape of the collapse area will be influenced by depth, size and shape of the magma chamber. The final morphology of a <span class="hlt">caldera</span> will depend on how the <span class="hlt">caldera</span> floor breaks up; whether collapse takes place in one event or multiple events, whether vertical movement is spasmodic or continuous throughout the eruptive sequence, and whether blocks subside uniformly or chaotically at one or more collapse centres. A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2010/1173/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2010/1173/"><span><span class="hlt">Caldera</span> demonstration model</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Venezky, Dina; Wessells, Stephen</p> <p>2010-01-01</p> <p>A <span class="hlt">caldera</span> is a large, usually circular volcanic depression formed when magma is withdrawn or erupted from a shallow underground magma reservoir. It is often difficult to visualize how <span class="hlt">calderas</span> form. This simple experiment using flour, a balloon, tubing, and a bicycle pump, provides a helpful visualization for <span class="hlt">caldera</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3540C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3540C"><span>Long time series of soil CO2 degassing measurements at Solfatara of Pozzuoli (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cardellini, Carlo; Chiodini, Giovanni; Rosiello, Angelo; Bagnato, Emanula; Avino, Rosario; Frondini, Francesco; Caliro, Stefano; Beddini, Giulio; Donnini, Marco; Lelli, Matto</p> <p>2016-04-01</p> <p>Since 1998, 28 extensive soil CO2 flux surveys, each including 400-500 measurements by accumulation chamber method, were performed over a large area (about 1.45 km2) covering the Solfatara crater and its surroundings. The statistical analysis of CO2 flux values, coupled with the measurement of the CO2 efflux isotopic composition, allowed to characterize the different CO2 sources feeding soil degassing and to investigate their temporal variability. Using a geostatistical approach the spatial structure of the degassing area, as well as the total amount of released CO2, have been defined. The area is characterized by a well defined diffuse degassing structure interested by the release of deeply derived CO2 (Solfatara DDS), which geometry is strongly controlled by volcanic and tectonic structures. The extension of the Solfatara DDS varied in the time with two major enlargements, the first consisted in its doubling in 2003-2004 and the second in further enlargement of about 30% occurred between 2011 and 2012. Both DDS enlargement mainly interested the area external to the crater in correspondence of the NE-SW fault system of Pisciarelli area. This area is also characterized by a very large increase in fumarolic emissions, in terms of both flow rate and discharge temperatures since 2005. The first event of DDS enlargements was previously correlated with the occurrence in 2000 of a relatively deep seismic swarm, which was interpreted as the indicator of the opening of an easy-ascent pathway for the transfer of magmatic fluids towards the shallower portion of the hydrothermal system; the second enlargement well correlates with the recent unrest phase of the system, characterized by an acceleration of the ground uplift. The amount of released CO2 has been estimated ranging between about 700 t/d and about 1500 t/d (with errors between 9 and 15 %) until the January 2015 when there was an increase up to 2800 t/d. After this maximum emission rate the flux slightly decrease during 2015 reaching again an CO2 output of 1500 t/d at November 2015. The CO2 variations in the last two years seems to follow the trend depicted by ground deformations, with increases of fluxes during the uplift accelerations and decreases of fluxes during the phases of relative "no-uplift". The comparison of the CO2 flux data with the chemical composition of the main fumaroles suggests that the variation of in the DDS extension is correlated to processes of condensation of the vapor plume feeding the Solfatara manifestation accompanied by an overall increase of the temperatures, caused by the arrival of increasing amounts of magmatic fluids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04445.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04445.html"><span>Pavonis Mons <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-03-19</p> <p>Pavonis Mons is the middle of the three large volcanoes on the Tharsis bulge. This image from NASA Mars Odyssey spacecraft covers the edge of the volcano <span class="hlt">caldera</span>. Outside of the <span class="hlt">caldera</span>, numerous lava flows and impact craters can be seen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21159.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21159.html"><span>Crater and <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-11-07</p> <p>This VIS image shows two circular features. The flat floored feature at the top of the image is the summit <span class="hlt">caldera</span> of Elysium Mons and was formed by volcanic activity. The bowl-shaped feature next to the <span class="hlt">caldera</span> is an impact crater. Orbit Number: 65587 Latitude: 24.3248 Longitude: 146.842 Instrument: VIS Captured: 2016-09-26 07:14 http://photojournal.jpl.nasa.gov/catalog/PIA21159</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991JVGR...48....1S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991JVGR...48....1S"><span>The structure of the Campanian Plain and the activity of the Neapolitan volcanoes (Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scandone, Roberto; Bellucci, Francesca; Lirer, Lucio; Rolandi, Giuseppe</p> <p>1991-08-01</p> <p>The central Campanian Plain is dominated by the structural depression of Acerra whose origin is tectonic, but may have been enlarged and further depressed after the eruption of the Campanian Ignimbrite (42-25 ka). The deposits of the Campanian Ignimbrite are possibly the results of multiple eruptions with huge pyroclastic deposits that covered all the Campanian Plain. The more recent activity of Vesuvius, <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Procida occurred on the borders of Acerra depression and resulted from a reactivation of regional faults after the Campanian Ignimbrite cycle. The activity of Vesuvius produced the building of a stratovolcano mostly by effusive and plinian explosive eruptions. The <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> area, on the contrary, was dominated by the eruption of the Neapolitan Yellow Tuff at 12 ka that produced a <span class="hlt">caldera</span> collapse of the Gulf of Pozzuoli. The <span class="hlt">caldera</span> formation controlled the emplacement of the recent activity of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and the new volcanoes were formed only within the <span class="hlt">caldera</span> or along its rim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26ES....3a1001G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26ES....3a1001G"><span>PREFACE: Collapse <span class="hlt">Calderas</span> Workshop</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gottsmann, Jo; Aguirre-Diaz, Gerardo</p> <p>2008-10-01</p> <p><span class="hlt">Caldera</span>-formation is one of the most awe-inspiring and powerful displays of nature's force. Resultant deposits may cover vast areas and significantly alter the immediate topography. Post-collapse activity may include resurgence, unrest, intra-<span class="hlt">caldera</span> volcanism and potentially the start of a new magmatic cycle, perhaps eventually leading to renewed collapse. Since volcanoes and their eruptions are the surface manifestation of magmatic processes, <span class="hlt">calderas</span> provide key insights into the generation and evolution of large-volume silicic magma bodies in the Earth's crust. Despite their potentially ferocious nature, <span class="hlt">calderas</span> play a crucial role in modern society's life. Collapse <span class="hlt">calderas</span> host essential economic deposits and supply power for many via the exploitation of geothermal reservoirs, and thus receive considerable scientific, economic and industrial attention. <span class="hlt">Calderas</span> also attract millions of visitors world-wide with their spectacular scenic displays. To build on the outcomes of the 2005 <span class="hlt">calderas</span> workshop in Tenerife (Spain) and to assess the most recent advances on <span class="hlt">caldera</span> research, a follow-up meeting was proposed to be held in Mexico in 2008. This abstract volume presents contributions to the 2nd <span class="hlt">Calderas</span> Workshop held at Hotel Misión La Muralla, Querétaro, Mexico, 19-25 October 2008. The title of the workshop `Reconstructing the evolution of collapse <span class="hlt">calderas</span>: Magma storage, mobilisation and eruption' set the theme for five days of presentations and discussions, both at the venue as well as during visits to the surrounding <span class="hlt">calderas</span> of Amealco, Amazcala and Huichapan. The multi-disciplinary workshop was attended by more than 40 scientist from North, Central and South America, Europe, Australia and Asia. Contributions covered five thematic topics: geology, geochemistry/petrology, structural analysis/modelling, geophysics, and hazards. The workshop was generously supported by the International Association of Volcanology and the Chemistry of The Earth's Interior</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4009C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4009C"><span><span class="hlt">Calderas</span> and magma reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cashman, Katharine; Giordano, Guido</p> <p>2015-04-01</p> <p>Large <span class="hlt">caldera</span>-forming eruptions have long been a focus of both petrological and volcanological studies; traditionally, both have assumed that eruptible magma is stored within a single long-lived melt body. Over the past decade, however, advances in analytical techniques have provided new views of magma storage regions, many of which provide evidence of multiple melt lenses feeding a single eruption, and/or rapid pre-eruptive assembly of large volumes of melt. These new petrological views of magmatic systems have not yet been fully integrated into volcanological perspectives of <span class="hlt">caldera</span>-forming eruptions. We discuss the implications of syn-eruptive melt extraction from complex, rather than simple, reservoirs and its potential control over eruption size and style, and <span class="hlt">caldera</span> collapse timing and style. Implications extend to monitoring of volcanic unrest and eruption progress under conditions where successive melt lenses may be tapped. We conclude that emerging views of complex magma reservoir configurations provide exciting opportunities for re-examining volcanological concepts of <span class="hlt">caldera</span>-forming systems</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..288...28C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..288...28C"><span><span class="hlt">Calderas</span> and magma reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cashman, Katharine V.; Giordano, Guido</p> <p>2014-11-01</p> <p>Large <span class="hlt">caldera</span>-forming eruptions have long been a focus of both petrological and volcanological studies; petrologists have used the eruptive products to probe conditions of magma storage (and thus processes that drive magma evolution), while volcanologists have used them to study the conditions under which large volumes of magma are transported to, and emplaced on, the Earth's surface. Traditionally, both groups have worked on the assumption that eruptible magma is stored within a single long-lived melt body. Over the past decade, however, advances in analytical techniques have provided new views of magma storage regions, many of which provide evidence of multiple melt lenses feeding a single eruption, and/or rapid pre-eruptive assembly of large volumes of melt. These new petrological views of magmatic systems have not yet been fully integrated into volcanological perspectives of <span class="hlt">caldera</span>-forming eruptions. Here we explore the implications of complex magma reservoir configurations for eruption dynamics and <span class="hlt">caldera</span> formation. We first examine mafic systems, where stacked-sill models have long been invoked but which rarely produce explosive eruptions. An exception is the 2010 eruption of Eyjafjallajökull volcano, Iceland, where seismic and petrologic data show that multiple sills at different depths fed a multi-phase (explosive and effusive) eruption. Extension of this concept to larger mafic <span class="hlt">caldera</span>-forming systems suggests a mechanism to explain many of their unusual features, including their protracted explosivity, spatially variable compositions and pronounced intra-eruptive pauses. We then review studies of more common intermediate and silicic <span class="hlt">caldera</span>-forming systems to examine inferred conditions of magma storage, time scales of melt accumulation, eruption triggers, eruption dynamics and <span class="hlt">caldera</span> collapse. By compiling data from large and small, and crystal-rich and crystal-poor, events, we compare eruptions that are well explained by simple evacuation of a zoned</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA573600','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA573600"><span>Deep Explosive Volcanism on the Gakkel Ridge and Seismological Constraints on Shallow Recharge at TAG Active Mound</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-02-01</p> <p>movements at <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> , J. Geodyn., 32, 487-517, doi:10.1016/S0264-3707(01)00045-X. Deichmann, N. (2006), Local magnitude, a moment revisited...Malin, and E. Shalev (2004), Non-double-couple microearthquakes at Long Valley <span class="hlt">Caldera</span> , California, provide evidence for hydraulic fracturing, J...2009), Numerical models of <span class="hlt">caldera</span> deformation: Effects of multiphase and multicomponent hydrothermal fluid flow, J. Geophys. Res., 114(B04411), doi</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04069&hterms=summit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsummit','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04069&hterms=summit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsummit"><span>Pavonis Mons Summit <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/>This image shows part of the summit <span class="hlt">caldera</span> of Pavonis Mons. Pavonis the middle of three Tharsis volcanos that form a line southeast of Olympus Mons and northwest of Vallis Marineris. On Earth volcanic <span class="hlt">calderas</span> usually form when a massive eruption has emptied out the magma chamber and the 'roof' of the chamber collapses into the resultant space. It is likely that summit <span class="hlt">calderas</span> on Martian volcanoes form in a similar manner.<p/>Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.<p/>NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.<p/></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913169S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913169S"><span>Use of multiple in situ instruments and remote sensed satellite data for calibration tests at Solfatara (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic area)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Silvestri, Malvina; Musacchio, Massimo; Fabrizia Buongiorno, Maria; Doumaz, Fawzi; Andres Diaz, Jorge</p> <p>2017-04-01</p> <p>Monitoring natural hazards such as active volcanoes requires specific instruments to measure many parameters (gas emissions, surface temperatures, surface deformation etc.) to determine the activity level of a volcano. Volcanoes in most cases present difficult and dangerous environment for scientists who need to take in situ measurements. Remote Sensing systems on board of satellite permit to measure a large number of parameters especially during the eruptive events but still show large limits to monitor volcanic precursors and phenomena at local scale (gas species emitted by fumarole or summit craters degassing plumes and surface thermal changes of few degrees) for their specific risk. For such reason unmanned aircraft systems (UAS) mounting a variety of multigas sensors instruments (such as miniature mass spectrometer) or single specie sensors (such as electrochemical and IR sensors) allow a safe monitoring of volcanic activities. With this technology, it is possible to perform monitoring measurements of volcanic activity without risking the lives of scientists and personnel performing analysis during the field campaigns in areas of high volcanic activity and supporting the calibration and validation of satellite data measurements. These systems allowed the acquisition of real-time information such as temperature, pressure, relative humidity, SO2, H2S, CO2 contained in degassing plume and fumaroles, with GPS geolocation. The acquired data are both stored in the sensor and transmitted to a computer for real time viewing information. Information in the form of 3D concentration maps can be returned. The equipment used during the campaigns at Solfatara Volcano (in 2014, 2015 and 2016) was miniaturized instruments allowed measurements conducted either by flying drones over the fumarolic sites and by hand carrying into the fumaroles. We present the results of the field campaign held in different years at the Solfatara of Pozzuoli, near Naples, concerning measurements of CO2, H2S and SO2. The campaigns were carried out in collaboration with the University of Costa Rica and Jet Propulsion Laboratory of the California Institute of Technology (Pasadena, California) and has allowed the acquisition of a number of measures through scientific miniaturized multi-gas, thermal cameras and spectro-radiometer. The acquired measurements have also permitted the calibration and validation of satellite data as ASTER and LANDSAT8 (in collaboration with USGS). We believe that the rapid increasing of technology developments will permit the use UAS to integrate geophysical measurements and contribute to the necessary calibration and validation of current and future satellite missions dedicated to the measurements of surface temperatures and gas emissions in volcanic areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V13C3127C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V13C3127C"><span>Diffuse Soil CO2 Degassing at Solfatara of Pozzuoli (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy): 1998-2015, Sixteen Years of Flux Measurement.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cardellini, C.; Chiodini, G.; Caliro, S.; Quareni, F.; Frondini, F.; Rosiello, A.; Avino, R.; Bagnato, E.</p> <p>2015-12-01</p> <p>Solfatara of Pozzuoli is one of the largest studied volcanic-hydrothermal system of the world releasing a large amount of deeply derived fluids. Since 1998, extensive soil CO2 flux surveys where performed using the accumulation chamber method over a large area (1.45 km2). The statistical analysis of CO2 flux, coupled with the investigation of the CO2 efflux isotopic composition, allowed to characterize the different CO2 sources and to investigate their temporal variability. The geostatistical elaboration of CO2 fluxes allowed to define the spatial structure of the degassing area, as well as the total amount of released CO2, pointing out the presence of a well defined diffuse degassing structure interested by the release of deeply derived CO2 (Solfatara DDS). The extension of the DDS experienced relevant variations with two major enlargements, the first consisted in its doubling in 2003-2004 and the second in further enlargement of about 30% in 2011-2012. These variations mainly occurred external to the crater area in correspondence of a NE-SW fault system (Pisciarelli area). The first event was previously correlated with the occurrence in 2000 of a relatively deep seismic swarm, which was interpreted as the indicator of the opening of an easy-ascent pathway for the transfer of magmatic fluids towards the shallower portion of the hydrothermal system; the second enlargement well correlates with the recent unrest phase of the system, characterized by an acceleration of the ground uplift. The amount of released CO2 has been estimated ranging between about 700 t/d and about 1500 t/d (with errors between 9 and 15 %) until the January 2015 when there was an increase up to 2800 t/d. The CO2 variations in the last two years seems to follow the trend depicted by ground deformations, with increases of fluxes during the uplift accelerations and decreases of fluxes during the phases of relative "no-uplift". The comparison of the CO2 flux data with the chemical composition of the main fumaroles suggests that the variation of in the DDS extension is correlated to processes of condensation of the vapor plume feeding the Solfatara manifestation accompanied by an overall increase of the temperatures, caused by the arrival of increasing amounts of deep fluids, possibly magmatic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..321..149S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..321..149S"><span>Comparative proximal features of the main Plinian deposits (Campanian Ignimbrite and Pomici di Base) of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> and Vesuvius</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarpati, Claudio; Sparice, Domenico; Perrotta, Annamaria</p> <p>2016-07-01</p> <p>The proximal Plinian fall deposits of the Campanian Ignimbrite (CI; 38 ky, Fedele et al., 2008) and Pomici di Base (PdB; 18 ky, Bertagnini et al., 1998) have been investigated in order to understand the contribution of each part of the plume to the proximal sedimentation. Following Houghton et al. (2004b) we consider three main transport regimes: jet phase (producing facies Fb), buoyant region of the plume (producing facies Fa) and direct lateral ejection (producing facies Fc). As well documented in medial locations (Sparks et al., 1992, 1997; Ernst et al., 1996), transport regimes can develop different facies even in proximal locations according to the dynamics of the eruptive column. Our proximal deposits show stratification and diffuse bedding allowing us to introduce two new facies: stratified Fa (sFa) and diffuse bedded Fb (dbFb). These facies retain the transport regime previously proposed for Fa (buoyant plume) and Fb (jet phase) but their lithological features are influenced by near-vent depositional conditions. Lithology and sedimentological data (grain-size, componentry, maximum clasts) suggest that most of the sedimentation occurred mainly from the buoyant plume with simultaneous contribution from the other two different dynamic regimes. Coarse clasts falling from the lower margins of the plume strongly affected the sedimentation of the CI proximal fall deposit with a minor contribution from lithic clasts ballistically emplaced and partial collapses of the plume forming pyroclastic density currents. In contrast, the PdB proximal fall deposit was strongly affected by coarse clasts emplaced directly from the vent through parabolic trajectories, with very little contribution of material emplaced from the lower part of the plume. These differences can be attributed to different vent/conduit processes acting during the eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1713496F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713496F"><span>Monitoring the geothermal fluid using time lapse electrical resistivity tomography: The Pisciarelli fumarolic field test site (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, South Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedele, Alessandro; Giulia Di Giuseppe, Maria; Troiano, Antonio; Somma, Reanto; Caputo, Teresa; Patella, Domenico; Troise, Claudia; De Natale, Giuseppe</p> <p>2015-04-01</p> <p>Pisciarelli area is a fumarolic field subject to very short time morphological changes. A number of critical problems affect this area, i.e. increase of temperature of the fumaroles above the average background temperature, local seismicity and occurrence of fumaroles mixed with jets of boiling water. The presence of a very shallow aquifer seem to have the control on the behavior and composition of the fumaroles. This fumarolic field is still largely unknown regarding geophysical surveys mainly because of its limited space, surrounded on the eastern side by intense urbanization inside the large Agnano crater (Troiano et al. 2014). Currently is mainly affected by geochemical, thermal and seismic monitoring which may not fully explain the behaviour of fluids surface. Many monitoring or time lapse (TL) applications are discussed in literature (e.g., White, 1994; Daily et al., 1995; Barker and Moore, 1998; Ramirez and Daily, 2001; Carter, 2002; Slater et al., 2002; Singha and Gorelick, 2005; Cassiani et al., 2006; Swarzenski et al., 2006; de Franco et al., 2009). However all these experiments are devoted to the use of the ERT for tracer tests or in contaminant hydrology and are characterized by a short monitoring period due to the complexity and problems of long-time instrument maintenance. We propose and present a first approach of a geophysical monitoring by time lapse electrical resistivity in a fumarolic field. The profiles were acquired in January 2013, in January, March, May, July, September and November 2014 respectively. They cross the Pisciarelli area following approximately the NS direction and were characterized by a 2.5 m electrode spacing and maximum penetration depth of about 20 m. and will supply fundamental evidences on the possible seasonal resistivity fluctuations or if the resistivity changes are indicative of an increase in volcanic gases present in the hydrothermal system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03601.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03601.html"><span>Io Tupan <span class="hlt">Caldera</span> in Infrared</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2001-12-10</p> <p>Tupan <span class="hlt">Caldera</span>, a volcanic crater on Jupiter moon Io, has a relatively cool area, possibly an island, in its center, as indicated by infrared imagery from NASA Galileo spacecraft during an Oct. 16, 2001 flyby.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V33C2651S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V33C2651S"><span>A model for <span class="hlt">caldera</span> resurgence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stix, J.; kennedy, B.; Wilcock, J.</p> <p>2011-12-01</p> <p>A key question in volcanology is the driving mechanisms of resurgence at active, recently active, and ancient <span class="hlt">calderas</span>. Valles <span class="hlt">caldera</span> in New Mexico and Lake City <span class="hlt">caldera</span> in Colorado are well-studied resurgent structures which provide two crucial clues for understanding the resurgence process. (1) Within the limits of 40Ar/39Ar dating techniques, resurgence at both <span class="hlt">calderas</span> occurred very quickly after the <span class="hlt">caldera</span>-forming eruptions (tens of thousands of years or less). (2) Immediately before and during resurgence, dacite magma was intruded and/or erupted; this magma is chemically distinct from rhyolite magma erupted from the shallow magma chamber as ignimbrite. These observations demonstrate that resurgence is temporally linked to <span class="hlt">caldera</span> subsidence, with the dacite magma as the driver of resurgence. Recharge of dacite magma occurs as a response to loss of lithostatic load during the <span class="hlt">caldera</span>-forming eruption. Flow of dacite into the shallow magmatic system is facilitated by regional faults which provide pathways for magma ascent. Once the dacite enters the system, it is able to heat and remobilize residual crystal-rich rhyolite remaining in the shallow magma chamber. Surface resurgent uplift is produced by dacite and remobilized rhyolite rising through buoyancy, and by roof blocks sinking partway into the magma chamber. The resurgent deformation caused by magma ascent fractures the chamber roof, increasing its structural permeability and allowing both rhyolite and dacite magma to be intruded and/or erupted together. These same processes facilitate mingling and mixing of the dacite and rhyolite magmas. This sequence of events also promotes the development of magmatic-hydrothermal systems and ore deposits. Injection of dacite magma into the shallow rhyolite magma chamber provides a source of heat and magmatic volatiles, while resurgent deformation and fracturing increase the permeability of the system. These changes allow magmatic volatiles to rise and meteoric fluids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00473.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00473.html"><span>Venus - Sag <span class="hlt">Caldera</span> Sachs Patera</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1996-11-20</p> <p>This image from NASA Magellan spacecraft is of Sachs Patera on Venus, centered at 49 degrees north, 334 degrees east. Defined as a sag-<span class="hlt">caldera</span>, Sachs is an elliptical depression 130 meters (81 feet) in depth, spanning 40 kilometers (25 miles) in width along its longest axis. The morphology implies that a chamber of molten material drained and collapsed, forming a depression surrounded by concentric scarps spaced 2-to-5 kilometers (1.2- to-3 miles) apart. The arc-shaped set of scarps, extending out to the north from the prominent ellipse, is evidence for a separate episode of withdrawal; the small lobe-shaped extension to the southwest may represent an additional event. Solidified lava flows 10-to-25 kilometers (6-to-16 miles) long, give the <span class="hlt">caldera</span> its flower-like appearance. The flows are a lighter tone of gray in the radar data because the lava is blockier in texture and consequently returns more radar waves. Much of the lava, which was evacuated from the chamber, probably traveled to other locations underground, while some of it may have surfaced further south. This is unlike <span class="hlt">calderas</span> on Earth, where a rim of lava builds up in the immediate vicinity of the <span class="hlt">caldera</span>. http://photojournal.jpl.nasa.gov/catalog/PIA00473</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00473&hterms=sag&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsag','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00473&hterms=sag&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsag"><span>Venus - Sag <span class="hlt">Caldera</span> 'Sachs Patera</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>This image of Sachs Patera on Venus is centered at 49 degrees north, 334 degrees east. Defined as a sag-<span class="hlt">caldera</span>, Sachs is an elliptical depression 130 meters (81 feet) in depth, spanning 40 kilometers (25 miles) in width along its longest axis. The morphology implies that a chamber of molten material drained and collapsed, forming a depression surrounded by concentric scarps spaced 2-to-5 kilometers (1.2- to-3 miles) apart. The arc-shaped set of scarps, extending out to the north from the prominent ellipse, is evidence for a separate episode of withdrawal; the small lobe-shaped extension to the southwest may represent an additional event. Solidified lava flows 10-to-25 kilometers (6-to-16 miles) long, give the <span class="hlt">caldera</span> its flower-like appearance. The flows are a lighter tone of gray in the radar data because the lava is blockier in texture and consequently returns more radar waves. Much of the lava, which was evacuated from the chamber, probably traveled to other locations underground, while some of it may have surfaced further south. This is unlike <span class="hlt">calderas</span> on Earth, where a rim of lava builds up in the immediate vicinity of the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EOSTr..92...53A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EOSTr..92...53A"><span>Improving and Facilitating Research on Collapse <span class="hlt">Calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Diaz, Gerardo; Geyer, Adelina; Martí, Joan; Acocella, Valerio</p> <p>2011-02-01</p> <p>Roughly circular depressions known as <span class="hlt">calderas</span> are distinctive features in volcanic areas (see Figure 1). Current views explain a <span class="hlt">caldera</span> as the surface expression of a magma chamber's collapsed roof after magma drains elsewhere. Although not all <span class="hlt">calderas</span> are associated with explosive activity, most major eruptions (i.e., those with a volcanic explosivity index of 5 or higher) develop such collapse <span class="hlt">calderas</span>. <span class="hlt">Calderas</span> are usually associated with magmatic systems that have endured for thousands of years at least. These systems undergo periods of unrest highlighted by ground displacement, seismicity, and gas emissions. As a consequence, <span class="hlt">calderas</span> are some of the most studied volcanic features, particularly for their possible implications for hazard assessment and mitigation. In addition, <span class="hlt">calderas</span> can be associated with geothermal and ore resources and can affect climate through the products they emit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.V14B..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.V14B..03H"><span><span class="hlt">Caldera</span> Ellipticity Through Regional Tectonic Deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holohan, E. P.; Troll, V. R.; Walter, T. R.; van Wyk de Vries, B.; Byrne, P. K.</p> <p>2005-12-01</p> <p>Collapse <span class="hlt">calderas</span> are delimited by reverse ring faults and surrounded by peripheral concentric normal faults. In the simplest scenario, circular magma chambers produce circular <span class="hlt">calderas</span>. Many <span class="hlt">calderas</span> are elliptical in shape, however, particularly those in highly active tectonic settings. Several factors may explain <span class="hlt">caldera</span> ellipticity in such regimes: 1) Initial geometry of magma chamber(s) 2) Distribution and orientation of pre-existing regional faults, and 3) Influence of the regional stress field on <span class="hlt">caldera</span> fault geometries. To better understand relationships between <span class="hlt">caldera</span> morphology, reservoir geometry and regional tectonics, we conducted two analogue experimental series: One series investigated the influence of orthogonal tectonic stresses on <span class="hlt">caldera</span> and chamber shapes. In all cases where tectonic stress was applied across circular chambers (balloons), elliptical <span class="hlt">calderas</span> were produced. Pre-existing basement structures also influenced the shape of <span class="hlt">calderas</span>, either increasing or reducing elongation. Intrusion of silicon gel into tectonically active sand piles showed that silicon gel chambers responded systematically to applied tectonic stress, and that associated <span class="hlt">calderas</span> would be elliptical in shape. A second series examined the effect of strike slip faulting on magma chambers and associated <span class="hlt">calderas</span>. We used sand to simulate brittle crust and cream honey to simulate granitic magma. With a sufficiently high transtensive component, pull-apart-like half grabens formed above the passive honey chamber. Chamber evacuation following strike-slip deformation produced arcuate reverse faults that were again occasionally affected by regional structures. From our results, we identify a number of controls for elliptical <span class="hlt">caldera</span> formation in tectonically active settings, including initial chamber geometry, <span class="hlt">caldera</span> fault distortion, and interaction with pre-existing structures. Our results indicate that the final <span class="hlt">caldera</span> surface expression will be the result of interplay</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-s26-38-056.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-s26-38-056.html"><span>Tambora <span class="hlt">Caldera</span>, Sumbawa Island, Indonesia</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1988-10-03</p> <p>STS026-038-056 (29 Sept. - 3 Oct. 1988) --- Tambora <span class="hlt">Caldera</span>, Sumbawa Island, Indonesia as photographed with a 70mm handheld Hasselblad camera. Tambora is a 6-kilometer-wide and 650-meter-deep <span class="hlt">Caldera</span> formed in 1815 as a result of a huge volcanic eruption. Gases from the eruption were ejected high into Earth's atmosphere and transported around the globe. The atmospheric gases trapped part of the incoming sunglint, resulting in extremely cold weather. In New England, snow fell in June, and freezes occurred throughout the summer of 1816, which became known as "the year without a summer." This photo was shown by the STS-26 astronaut crew during its Oct. 11, l988 post-flight press conference.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5611189','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5611189"><span>New light on <span class="hlt">caldera</span> evolution - Askja, Iceland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, G.C.; Everett, S.P.; Rymer, H.; McGarvie, D.W.; Foster I. )</p> <p>1991-04-01</p> <p>The large multiple-<span class="hlt">caldera</span> volcanic system of Askja, central Iceland, is composed principally of subglacial basaltic hyaloclastite-pillow-lava formations and postglacial basaltic scoria and flows. Traditionally, such <span class="hlt">calderas</span> are believed to be formed by downfaulting and ring-fracture collapse. Whereas this certainly applies to the smaller A.D. 1875 <span class="hlt">caldera</span>, the older main <span class="hlt">caldera</span> may have developed positive relief during subglacial construction of laterally confined hyaloclastite ridges above erupting fractures. This is supported by the evidence of a large negative gravity anomaly that reaches minima over the marginal low-density ridges but which is less negative within the <span class="hlt">caldera</span>, where relatively dense postglacial lavas are believed to cover a more limited hyaloclastite succession beneath the <span class="hlt">caldera</span> floor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JChPh.141c4111C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JChPh.141c4111C"><span>Nonstatistical dynamics on the <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collins, Peter; Kramer, Zeb C.; Carpenter, Barry K.; Ezra, Gregory S.; Wiggins, Stephen</p> <p>2014-07-01</p> <p>We explore both classical and quantum dynamics of a model potential exhibiting a <span class="hlt">caldera</span>: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the "dynamical matching" phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a "stretched" version of the <span class="hlt">caldera</span> model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the <span class="hlt">caldera</span> potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the "dynamical matching" phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22419881','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22419881"><span>Nonstatistical dynamics on the <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collins, Peter; Wiggins, Stephen; Kramer, Zeb C. Ezra, Gregory S.; Carpenter, Barry K.</p> <p>2014-07-21</p> <p>We explore both classical and quantum dynamics of a model potential exhibiting a <span class="hlt">caldera</span>: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the “dynamical matching” phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a “stretched” version of the <span class="hlt">caldera</span> model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the <span class="hlt">caldera</span> potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the “dynamical matching” phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25053305','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25053305"><span>Nonstatistical dynamics on the <span class="hlt">caldera</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Collins, Peter; Kramer, Zeb C; Carpenter, Barry K; Ezra, Gregory S; Wiggins, Stephen</p> <p>2014-07-21</p> <p>We explore both classical and quantum dynamics of a model potential exhibiting a <span class="hlt">caldera</span>: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the "dynamical matching" phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a "stretched" version of the <span class="hlt">caldera</span> model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the <span class="hlt">caldera</span> potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the "dynamical matching" phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7346G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7346G"><span>The worldwide collapse <span class="hlt">caldera</span> database (CCDB): A tool for studying and understanding <span class="hlt">caldera</span> processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geyer, Adelina; Marti, Joan</p> <p>2015-04-01</p> <p>Collapse <span class="hlt">calderas</span> are one of the most important volcanic structures not only because of their hazard implications, but also because of their high geothermal energy potential and their association with mineral deposits of economic interest. In 2008 we presented a new general worldwide Collapse <span class="hlt">Caldera</span> DataBase (CCDB), in order to provide a useful and accessible tool for studying and understanding <span class="hlt">caldera</span> collapse processes. The principal aim of the CCDB is to update the current field based knowledge on <span class="hlt">calderas</span>, merging together the existing databases and complementing them with new examples found in the bibliography, and leaving it open for the incorporation of new data from future studies. Currently, the database includes over 450 documented <span class="hlt">calderas</span> around the world, trying to be representative enough to promote further studies and analyses. We have performed a comprehensive compilation of published field studies of collapse <span class="hlt">calderas</span> including more than 500 references, and their information has been summarized in a database linked to a Geographical Information System (GIS) application. Thus, it is possible to visualize the selected <span class="hlt">calderas</span> on a world map and to filter them according to different features recorded in the database (e.g. age, structure). The information recorded in the CCDB can be grouped in seven main information classes: <span class="hlt">caldera</span> features, properties of the <span class="hlt">caldera</span>-forming deposits, magmatic system, geodynamic setting, pre-<span class="hlt">caldera</span> volcanism,<span class="hlt">caldera</span>-forming eruption sequence and post-<span class="hlt">caldera</span> activity. Additionally, we have added two extra classes. The first records the references consulted for each <span class="hlt">caldera</span>. The second allows users to introduce comments on the <span class="hlt">caldera</span> sample such as possible controversies concerning the <span class="hlt">caldera</span> origin. During the last seven years, the database has been available on-line at http://www.gvb-csic.es/CCDB.htm previous registration. This year, the CCDB webpage will be updated and improved so the database content can be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019313','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019313"><span>Subsidence of ash-flow <span class="hlt">calderas</span>: Relation to <span class="hlt">caldera</span> size and magma-chamber geometry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lipman, P.W.</p> <p>1997-01-01</p> <p>Diverse subsidence geometries and collapse processes for ash-flow <span class="hlt">calderas</span> are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary <span class="hlt">calderas</span>, a continuum of geometries and subsidence styles is inferred to exist, in both island-arc and continental settings, between small funnel <span class="hlt">calderas</span> and larger plate (piston) subsidences bounded by arcuate faults. Within most ring-fault <span class="hlt">calderas</span>, the subsided block is variably disrupted, due to differential movement during ash-flow eruptions and postcollapse magmatism, but highly chaotic piecemeal subsidence appears to be uncommon for large-diameter <span class="hlt">calderas</span>. Small-scale downsag structures and accompanying extensional fractures develop along margins of most <span class="hlt">calderas</span> during early stages of subsidence, but downsag is dominant only at <span class="hlt">calderas</span> that have not subsided deeply. <span class="hlt">Calderas</span> that are loci for multicyclic ash-flow eruption and subsidence cycles have the most complex internal structures. Large <span class="hlt">calderas</span> have flared inner topographic walls due to landsliding of unstable slopes, and the resulting slide debris can constitute large proportions of <span class="hlt">caldera</span> fill. Because the slide debris is concentrated near <span class="hlt">caldera</span> walls, models from geophysical data can suggest a funnel geometry, even for large plate-subsidence <span class="hlt">calderas</span> bounded by ring faults. Simple geometric models indicate that many large <span class="hlt">calderas</span> have subsided 3-5 km, greater than the depth of most naturally exposed sections of intracaldera deposits. Many ring-fault platesubsidence <span class="hlt">calderas</span> and intrusive ring complexes have been recognized in the western U.S., Japan, and elsewhere, but no well-documented examples of exposed eroded <span class="hlt">calderas</span> have large-scale funnel geometry or chaotically disrupted <span class="hlt">caldera</span> floors. Reported ignimbrite "shields" in the central Andes, where large-volume ash-flows are inferred to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997BVol...59..198L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997BVol...59..198L"><span>Subsidence of ash-flow <span class="hlt">calderas</span>: relation to <span class="hlt">caldera</span> size and magma-chamber geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lipman, Peter W.</p> <p></p> <p>Diverse subsidence geometries and collapse processes for ash-flow <span class="hlt">calderas</span> are inferred to reflect varying sizes, roof geometries, and depths of the source magma chambers, in combination with prior volcanic and regional tectonic influences. Based largely on a review of features at eroded pre-Quaternary <span class="hlt">calderas</span>, a continuum of geometries and subsidence styles is inferred to exist, in both island-arc and continental settings, between small funnel <span class="hlt">calderas</span> and larger plate (piston) subsidences bounded by arcuate faults. Within most ring-fault <span class="hlt">calderas</span>, the subsided block is variably disrupted, due to differential movement during ash-flow eruptions and postcollapse magmatism, but highly chaotic piecemeal subsidence appears to be uncommon for large-diameter <span class="hlt">calderas</span>. Small-scale downsag structures and accompanying extensional fractures develop along margins of most <span class="hlt">calderas</span> during early stages of subsidence, but downsag is dominant only at <span class="hlt">calderas</span> that have not subsided deeply. <span class="hlt">Calderas</span> that are loci for multicyclic ash-flow eruption and subsidence cycles have the most complex internal structures. Large <span class="hlt">calderas</span> have flared inner topographic walls due to landsliding of unstable slopes, and the resulting slide debris can constitute large proportions of <span class="hlt">caldera</span> fill. Because the slide debris is concentrated near <span class="hlt">caldera</span> walls, models from geophysical data can suggest a funnel geometry, even for large plate-subsidence <span class="hlt">calderas</span> bounded by ring faults. Simple geometric models indicate that many large <span class="hlt">calderas</span> have subsided 3-5km, greater than the depth of most naturally exposed sections of intracaldera deposits. Many ring-fault plate-subsidence <span class="hlt">calderas</span> and intrusive ring complexes have been recognized in the western U.S., Japan, and elsewhere, but no well-documented examples of exposed eroded <span class="hlt">calderas</span> have large-scale funnel geometry or chaotically disrupted <span class="hlt">caldera</span> floors. Reported ignimbrite "shields" in the central Andes, where large-volume ash-flows are inferred to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988EOSTr..69..697G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988EOSTr..69..697G"><span>Third hole planned at Valles <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gardner, Jamie</p> <p></p> <p>Valles <span class="hlt">caldera</span>, N. Mex., is the culmination of more than 13 million years of volcanism in the Jemez volcanic field and is an excellent model for resurgent <span class="hlt">calderas</span> and for the high-temperature geothermal systems found with them. This month one of the biggest diamond drills in the world will start the third research core hole in the <span class="hlt">caldera</span>. Valles <span class="hlt">Caldera</span> 2B will be the tenth core hole in the Department of Energy's Continental Scientific Drilling Program.CSDP drilling in the 1.1-million-year-old <span class="hlt">caldera</span> began in 1984 in the southwest moat zone when the research hole Valles <span class="hlt">Caldera</span> 1 was continuously cored to 856 m. VC-1 intersected a hydrothermal outflow plume from the deep geothermal system. Data indicate multiple episodes of hydrothermal activity in the volcanic field's history, as well as multiple episodes of rhyolite magma generation during evolution of the <span class="hlt">caldera</span>. The June 10, 1988 (vol. 63), issue of Journal of Geophysical Research—Solid Earth and Planets carried a special section on results from VC-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910013685','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910013685"><span>Evolution of the Olympus Mons <span class="hlt">Caldera</span>, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mouginis-Mark, Peter J.; Robinson, Mark S.; Zuber, Maria T.</p> <p>1990-01-01</p> <p>Extensive high-resolution (15 to 20 m/pixel) coverage of Olympus Mons volcano permits the investigation of the sequence of events associated with the evolution of the nested summit <span class="hlt">caldera</span>. The sequence of the intra-<span class="hlt">caldera</span> events is well illustrated by image data collected on orbits 473S and 474S of Viking Orbiter 1. These data cover both the oldest and youngest portions of the <span class="hlt">caldera</span> floor. The chronology inferred from the observations is presented which in turn can be interpreted in terms of the internal structure of the volcano (i.e., magma chamber depth and the existence of dikes).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..324..105F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..324..105F"><span>A chemostratigraphic study of the Campanian Ignimbrite eruption (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy): Insights on magma chamber withdrawal and deposit accumulation as revealed by compositionally zoned stratigraphic and facies framework</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedele, L.; Scarpati, C.; Sparice, D.; Perrotta, A.; Laiena, F.</p> <p>2016-09-01</p> <p>Petrochemical analyses of juvenile samples from twenty stratigraphic sections of the Campanian Ignimbrite medial deposits, located from 30 to 79 km from the vent, are presented here. Sampling has accurately followed a well-defined stratigraphic framework and the new component facies scheme. The Campanian Ignimbrite succession is formed by a basal plinian pumice fall deposit, overlain by a complex architecture of pyroclastic density current deposits emplaced from a single sustained pyroclastic density current through a mechanism of vertical and lateral accretion. The deposit is broadly zoned, from more evolved trachyte at its base to less evolved trachyte at its top, and is similarly less evolved with increasing distance from the area of emission. Irregular chemical trends are locally observed and interpreted to represent only a limited, "patchy" record of the entire vertical geochemical trend. The petrochemical variation observed horizontally was ascribed to changes in the flow dynamics and interaction between the advancing flow and the underlying topography. The results of this study were used to propose a unified volcanological-petrological model for the Campanian Ignimbrite eruption, taking into account the emplacement of both the proximal (i.e., the "Breccia Museo" formation) and medial deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSM.V42B..08T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSM.V42B..08T"><span>Trachyte Obsidian Blocks in the Lag-Breccia of Ignimbrite Campana (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Italy). Additional Experimental Data related to the magma ascent conditions.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trigila, R. C.; Dolfi, D.</p> <p>2007-05-01</p> <p>The Obsidian blocks occurring frequently in the Lag-breccia of the Ignimbrite Campana super-eruption (IC) have been found to mime strictly the magma composition and the phenocrysts assemblage of the main eruptive ash- flow unit, possibly representing a quenched fraction of the magmatic system. To date, in spite of the several investigations on the erupted rocks, conclusive data on the fissural vents location, intracrustal reservoir(s) depth and dissolved volatiles in the melt, are controversial. The obsidian blocks show, typically, millimetric euhedral sanidine phenocrysts (up to 10-12 vol.%) regularly associated with salitic pyroxene, corroded bytownite, euhedral andesine, ulvo-spinel, apatite and biotite (totalling 4-6 vol.%). All these phases, but the bytownite, appear to be in thermodynamic equilibrium with the melt as shown by the equilibrium experiments performed at subliquidus T and confining P(H2O) of 50, 100, and 200 MPa. At 100 and 200 MPa, in particular, the entry order of mineral phases is corresponding to the obsidian one, with near liquidus co-crystallization of pyroxene, plagioclase and ulvospinel. Crystallisation is scarce until the appearance of sanidine(40-60°C below the liquidus), which brings quickly to the complete solidification of the magmatic system. Other experiments at the same P's and T's just above liquidus were performed to determine the H2O solubility in the melt both under equilibrium conditions (respectively 2.6, 4.7, and 6.9 wt.%) and under slow decompression gradients. In these last experiments performed by decreasing the confining P from 100 to 50 MPa with gradients up to 0.02 MPa/s and delay times before quenching from 0 to 12 h, no vesiculation was observed at the SEM scale, despite the amount of dissolved H2O (3.4wt.%) resulted significantly higher than the equilibrium value at the final experimental P. The effect of slow decompression rates at shallow depths keeps the volatiles into the melt enhancing the magma ascent already triggered at higher depths by the increase of the dissolved H2O due to the extensive crystal-liquid fractionation from a parent magma basaltic-trachyandesitic in composition (Fowler et al., J. Petrol., 2007).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5305369','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5305369"><span><span class="hlt">Calderas</span> and mineralization: volcanic geology and mineralization in the Chianti <span class="hlt">caldera</span> complex, Trans-Pecos Texas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Duex, T.W.; Henry, C.D.</p> <p>1981-01-01</p> <p>This report describes preliminary results of an ongoing study of the volcanic stratigraphy, <span class="hlt">caldera</span> activity, and known and potential mineralization of the Chinati Mountains area of Trans-Pecos Texas. Many ore deposits are spatially associated with <span class="hlt">calderas</span> and other volcanic centers. A genetic relationship between <span class="hlt">calderas</span> and base and precious metal mineralization has been proposed by some and denied by others. Steven and others have demonstrated that <span class="hlt">calderas</span> provide an important setting for mineralization in the San Juan volcanic field of Colorado. Mineralization is not found in all <span class="hlt">calderas</span> but is apparently restricted to <span class="hlt">calderas</span> that had complex, postsubsidence igneous activity. A comparison of volcanic setting, volcanic history, <span class="hlt">caldera</span> evolution, and evidence of mineralization in Trans-Pecos to those of the San Juan volcanic field, a major mineral producer, indicates that Trans-Pecos Texas also could be an important mineralized region. The Chianti <span class="hlt">caldera</span> complex in Trans-Pecos Texas contains at least two <span class="hlt">calderas</span> that have had considerable postsubsidence activity and that display large areas of hydrothermal alteration and mineralization. Abundant prospects in Trans-Pecos and numerous producing mines immediately south of the Trans-Pecos volcanic field in Mexico are additional evidence that ore-grade deposits could occur in Texas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EOSTr..92Q..44T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EOSTr..92Q..44T"><span>Research Spotlight: Extraordinary uplift of Yellowstone <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tretkoff, Ernie</p> <p>2011-02-01</p> <p>In Yellowstone National Park, located in Wyoming, Montana, and Idaho, the Yellow­stone <span class="hlt">caldera</span>, which extends about 40 kilometers by 60 kilometers, began in 2004 a period of accelerated uplift, with rates of uplift as high as 7 centimeters per year. From 2006 to 2009 the uplift rate slowed. Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) ground deformation measurements described by Chang et al. show that in the northern <span class="hlt">caldera</span>, uplift decreased from 7 centimeters per year in 2006 to 5 in 2008 and 2 in 2009. In the southwestern portion of the <span class="hlt">caldera</span>, uplift decreased from 4 centimeters per year in 2006 to 2 in 2008 and 0.5 in 2009, demonstrating a spatial pattern of ground motion decrease from southwest to northeast along the <span class="hlt">caldera</span>. (”Geophysical Research Letters, doi:10.1029/2010GL045451, 2010)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V13A0644C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V13A0644C"><span><span class="hlt">Caldera</span> Formation on the Vance Seamounts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clague, D.; Paduan, J.; Cousens, B.; Cornejo, L.; Perfit, M.; Wendt, R.; Stix, J.; Helo, C.</p> <p>2006-12-01</p> <p>The Vance Seamounts are a chain of near-ridge volcanoes located just west of the southern Juan de Fuca Ridge. The six volcanoes are built on ocean crust ranging from 0.78 Ma at the southeastern end to 2.55 Ma in the northwest. Morphologic analysis indicates that the volcanoes were constructed sequentially and get younger to the southeast towards the ridge axis. Like many near-ridge volcanoes, some of the Vance Seamounts have large offset <span class="hlt">calderas</span> that presumably formed above evacuated shallow magma chambers within the upper ocean crust. In summer 2006, we completed 6 dives using MBARI's ROV Tiburon to study the formation of these <span class="hlt">calderas</span>. The floor of each <span class="hlt">caldera</span> consists of flat-lying volcaniclastite, under about 25 cm of pelagic sediment. Some <span class="hlt">caldera</span> floors have mounds of post-<span class="hlt">caldera</span> pillow flows. The <span class="hlt">caldera</span> walls have a lower section covered by talus and an upper section of interbedded massive flows with columnar joints (to 11 m thick) and pillow basalts. The top of each <span class="hlt">caldera</span> wall has a unit of volcanic mudstone to sandstone ranging from 20 cm to 2 m thick. The fine matrix of many of these samples is green hydrothermal clay. The finest siltstone to mudstone samples appear to be layers of massive tan hydrothermal clays. Talus fragments, lava and volcaniclastite outcrops are universally coated and cemented by 1 to 4 cm-thick deposits of hydrothermal Mn-oxide crusts, even on the youngest of the volcanoes. Volcanic particles in the sandstones are mostly dense angular glass, but bubble-wall fragments (limu o Pele) are present and indicate formation during low-energy pyroclastic eruptions. Without the few percent limu o Pele fragments, the glass fragments would resemble those inferred to form by quench granulation. We suggest that quench granulation is actually pyroclastic fragmentation that occurs as coalesced magmatic gas bubbles disrupt the molten lava surface at the vents. Our observations confirm that the more southeasterly offset <span class="hlt">calderas</span> truncated thick</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/wri/1983/4091/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/wri/1983/4091/report.pdf"><span>Hydrology of the Newberry Volcano <span class="hlt">caldera</span>, Oregon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sammel, E.A.; Craig, R.W.</p> <p>1983-01-01</p> <p>Precipitation in the Newberry <span class="hlt">Caldera</span> is very nearly in balance with evaporation, evapotranspiration, and streamflow. Calcium, magnesium, and bicarbonate ions predominate in the more dilute ground and surface water. Thermal waters from springs and wells have concentrations of 900 milligrams per liter or more and are characterized by high concentrations of sodium and sulfate. Attempts to account for the origin of the hot springs on the basis of mixing relations and isotopic analyses were inconclusive; the springs may represent mixtures of thermal and nonthermal water which are altered by gases rising from sources beneath the <span class="hlt">caldera</span> floor. Annual recharge to deep aquifers beneath the <span class="hlt">caldera</span> is probably in the range 2,500 to 6,500 acre-feet. Observations in a Geological Survey drill hole suggest that part of the water may flow to aquifers at depths as much as 1,900 feet beneath the <span class="hlt">caldera</span> floor. Potential recharge to a postulated geothermal reservoir probably is extremely small. (USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/484542','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/484542"><span>Intracaldera volcanism and sedimentation - Creede <span class="hlt">Caldera</span>, Colorado</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heiken, G.; Krier, D.; Snow, M.G.</p> <p>1997-06-01</p> <p>Within the Creede <span class="hlt">caldera</span>, Colorado, many of the answers to its postcaldera volcanic and sedimentary history lie within the sequence of tuffaceous elastic sedimentary rocks and tuffs known as the Creede Formation. The Creede Formation and its interbedded ash deposits were sampled by research coreholes Creede 1 and 2, drilled during the fall of 1991. In an earlier study of the Creede Formation, based on surface outcrops and shallow mining company coreholes, Heiken and Krier concluded that the process of <span class="hlt">caldera</span> structural resurgence was rapid and that a <span class="hlt">caldera</span> lake had developed in an annulus ({open_quotes}moat{close_quotes}) located between the resurgent dome and <span class="hlt">caldera</span> wall. So far we have a picture of intracaldera activity consisting of intermittent hydrovolcanic eruptions within a <span class="hlt">caldera</span> lake for the lower third of the Creede Formation, and both magmatic and hydrovolcanic ash eruptions throughout the top two-thirds. Most of the ash deposits interbedded with the moat sedimentary rocks are extremely fine-grained. Ash fallout into the moat lake and unconsolidated ash eroded from <span class="hlt">caldera</span> walls and the slopes of the resurgent dome were deposited over stream delta distributaries within relatively shallow water in the northwestern moat, and in deeper waters of the northern moat, where the <span class="hlt">caldera</span> was intersected by a graben. Interbedded with ash beds and tuffaceous siltstones are coarse-grained turbidites from adjacent steep slopes and travertine from fissure ridges adjacent to the moat. Sedimentation rates and provenance for elastic sediments are linked to the frequent volcanic activity in and near the <span class="hlt">caldera</span>; nearly all of the Creede Formation sedimentary rocks are tuffaceous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JVGR...85...99F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JVGR...85...99F"><span>Hidden <span class="hlt">calderas</span> evidenced by multisource geophysical data; example of Cappadocian <span class="hlt">Calderas</span>, Central Anatolia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Froger, J.-L.; Lénat, J.-F.; Chorowicz, J.; Le Pennec, J.-L.; Bourdier, J.-L.; Köse, O.; Zimitoglu, O.; Gündogdu, N. M.; Gourgaud, A.</p> <p>1998-10-01</p> <p>The Cappadocian volcanic field in central Anatolia (Turkey) is characterised by a sequence of 10 Neogene ignimbrites. The associated <span class="hlt">calderas</span> have been partly dismantled and buried by subsequent tectonic and sedimentary processes and, therefore, cannot be readily recognized in the field. Recent progress in the understanding of the stratigraphic correlations and flow patterns has identified two main probable source areas for the ignimbrites. Detailed study of these areas, based on gravity surveys, remote sensing data (SPOT and ERS1 images) and digital elevation models (DEM), has provided evidence for two major <span class="hlt">caldera</span> complexes and their relationship to old stratovolcanoes and Neogene tectonics. The older Nevsehir-Acigöl <span class="hlt">caldera</span> complex, located between the towns of Acigöl, Nevsehir and Cardak, is inferred to be the source of the Kavak and Zelve ignimbrites. The Nevsehir-Acigöl <span class="hlt">caldera</span> complex is defined mainly by a -35 mGal circular gravimetry anomaly about 15 km in diameter. The boundaries of this, now buried, <span class="hlt">caldera</span> complex are shown by high gradients on the Bouguer gravity anomaly map. The younger Derinkuyu <span class="hlt">caldera</span> complex, located between the Erdas stratovolcano and the Ciftlik basin, is inferred to be the source of the Sarimaden, Cemilköy, Gördeles and Kizilkaya ignimbrites. It is well-defined by a rectangular (35×23 km) gravity low (-30 mGal) with a positive high (+20 mGal) in the center. Gravity, remote sensing data and the DEM provide evidence that the Erdas stratovolcano, on the northern margin of the Derinkuyu <span class="hlt">caldera</span> complex, represents the remnants of a large stratovolcano partly cut by one or more <span class="hlt">caldera</span> collapses. The positive anomaly within the Derinkuyu <span class="hlt">caldera</span> complex is centered on the 15-km-wide Sahin Kalesi volcanic massif. Field evidence and structural features inferred from the DEM and remote sensing data strongly suggest that this massif is a resurgent doming associated with the Gördeles ignimbrite eruption. High-resolution ERS1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8112M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8112M"><span>Modeling sill intrusion in volcanic <span class="hlt">calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Macedonio, Giovanni; Giudicepietro, Flora; D'Auria, Luca; Martini, Marcello</p> <p>2015-04-01</p> <p>We present a numerical model for describing sill intrusion in volcanic <span class="hlt">calderas</span>. The dynamics of volcanic <span class="hlt">calderas</span> are often subject to long-term unrests, with remarkable ground deformation, seismicity, and geochemical changes, that do not culminate in an eruption. On the contrary, in some cases, unrests with minor geophysical changes are followed, in few months, by an eruption, as in the case of Rabaul <span class="hlt">Caldera</span> in 1994 and Sierra Negra (Galapagos) in 2005. The main common features of <span class="hlt">calderas</span> are the relevant ground deformations with intense uplift episodes, often followed by subsidence. We think that the process of sill intrusion can explain the common features observed on different <span class="hlt">calderas</span>. In our model, the sill, fed by a deeper magma reservoir, intrudes below a horizontal elastic plate, representing the overlying rocks and expands radially. The model is based on the numerical solution of the equation for the elastic plate, coupled with a Navier-Stokes equation for simulating magma intrusion in the viscous regime. The numerical simulations show that during the feeding process, the ground is subject to uplift. When the feeding stops a subsidence occurs in the central zone. For very low flexural rigidity of the elastic plate, the subsidence can occur even during the intrusion of the sill. The stress field produced by the intrusion is mainly concentrated in a circular zone that follows the sill intrusion front.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V33C0678G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V33C0678G"><span>Composite <span class="hlt">Calderas</span>: The Long and Short of it</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gravley, D. M.; Hasegawa, T.; Nakagawa, M.; Wilson, C. J.</p> <p>2006-12-01</p> <p><span class="hlt">Calderas</span> formed in supereruptions are normally linked to a single magma body. However, <span class="hlt">caldera</span> formation, regional tectonics, and multiple magma bodies may interact to form composite structures with complex geometries. The term composite <span class="hlt">caldera</span> is often used without reference as to whether the `composite' is in time or space. Three examples of composite <span class="hlt">caldera</span> styles from New Zealand and Japan show field, geophysical, geochemical and isotopic evidence to suggest that current models for the size, shape and evolution of <span class="hlt">calderas</span> may be too simplistic. In our examples, multiple separate magma bodies distributed in either space or time, or both, may play a significant role in composite <span class="hlt">caldera</span> formation. Multiple, clustered collapse events incremental in time: Akan <span class="hlt">caldera</span> in Hokkaido appears to be a single, rectangular shaped <span class="hlt">caldera</span>. However, the identification of 17 eruptive units spanning >1 Myr suggests that the <span class="hlt">caldera</span> evolved incrementally over time and space. New gravity data shows that the <span class="hlt">caldera</span> is actually a daisy-chain of 3 distinct collapse structures that can be correlated, using lithic componentry, to 3 major geochemical groups in the eruptive products. Multiple, clustered collapse events in a single eruption sequence: Shikotsu <span class="hlt">caldera</span> in Hokkaido was originally thought to have formed following the eruption of a single large zoned magma chamber. However, the <span class="hlt">caldera</span>-related deposits are characterized by several geochemically distinct pumice types that can not have been accommodated in a single magma system. Our studies suggest that the variations in pumice compositions are consistent with multiple distinct magma bodies feeding coeval eruptions from several vent sources within an area that collapsed to form a single <span class="hlt">caldera</span>. Paired <span class="hlt">calderas</span> with linking eruption-related regional faulting: Rotorua and Ohakuri <span class="hlt">calderas</span> in New Zealand are 30 km apart and formed in close succession during a complex but virtually continuous eruption sequence at ca. 240 ka</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...815248M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...815248M"><span>Post-supereruption recovery at Toba <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mucek, Adonara E.; Danišík, Martin; de Silva, Shanaka L.; Schmitt, Axel K.; Pratomo, Indyo; Coble, Matthew A.</p> <p>2017-05-01</p> <p>Large <span class="hlt">calderas</span>, or supervolcanoes, are sites of the most catastrophic and hazardous events on Earth, yet the temporal details of post-supereruption activity, or resurgence, remain largely unknown, limiting our ability to understand how supervolcanoes work and address their hazards. Toba <span class="hlt">Caldera</span>, Indonesia, caused the greatest volcanic catastrophe of the last 100 kyr, climactically erupting ~74 ka. Since the supereruption, Toba has been in a state of resurgence but its magmatic and uplift history has remained unclear. Here we reveal that new 14C, zircon U-Th crystallization and (U-Th)/He ages show resurgence commenced at 69.7+/-4.5 ka and continued until at least ~2.7 ka, progressing westward across the <span class="hlt">caldera</span>, as reflected by post-<span class="hlt">caldera</span> effusive lava eruptions and uplifted lake sediment. The major stratovolcano north of Toba, Sinabung, shows strong geochemical kinship with Toba, and zircons from recent eruption products suggest Toba's climactic magma reservoir extends beneath Sinabung and is being tapped during eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28508876','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28508876"><span>Post-supereruption recovery at Toba <span class="hlt">Caldera</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mucek, Adonara E; Danišík, Martin; de Silva, Shanaka L; Schmitt, Axel K; Pratomo, Indyo; Coble, Matthew A</p> <p>2017-05-16</p> <p>Large <span class="hlt">calderas</span>, or supervolcanoes, are sites of the most catastrophic and hazardous events on Earth, yet the temporal details of post-supereruption activity, or resurgence, remain largely unknown, limiting our ability to understand how supervolcanoes work and address their hazards. Toba <span class="hlt">Caldera</span>, Indonesia, caused the greatest volcanic catastrophe of the last 100 kyr, climactically erupting ∼74 ka. Since the supereruption, Toba has been in a state of resurgence but its magmatic and uplift history has remained unclear. Here we reveal that new (14)C, zircon U-Th crystallization and (U-Th)/He ages show resurgence commenced at 69.7±4.5 ka and continued until at least ∼2.7 ka, progressing westward across the <span class="hlt">caldera</span>, as reflected by post-<span class="hlt">caldera</span> effusive lava eruptions and uplifted lake sediment. The major stratovolcano north of Toba, Sinabung, shows strong geochemical kinship with Toba, and zircons from recent eruption products suggest Toba's climactic magma reservoir extends beneath Sinabung and is being tapped during eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5440807','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5440807"><span>Post-supereruption recovery at Toba <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mucek, Adonara E.; Danišík, Martin; de Silva, Shanaka L.; Schmitt, Axel K.; Pratomo, Indyo; Coble, Matthew A.</p> <p>2017-01-01</p> <p>Large <span class="hlt">calderas</span>, or supervolcanoes, are sites of the most catastrophic and hazardous events on Earth, yet the temporal details of post-supereruption activity, or resurgence, remain largely unknown, limiting our ability to understand how supervolcanoes work and address their hazards. Toba <span class="hlt">Caldera</span>, Indonesia, caused the greatest volcanic catastrophe of the last 100 kyr, climactically erupting ∼74 ka. Since the supereruption, Toba has been in a state of resurgence but its magmatic and uplift history has remained unclear. Here we reveal that new 14C, zircon U–Th crystallization and (U–Th)/He ages show resurgence commenced at 69.7±4.5 ka and continued until at least ∼2.7 ka, progressing westward across the <span class="hlt">caldera</span>, as reflected by post-<span class="hlt">caldera</span> effusive lava eruptions and uplifted lake sediment. The major stratovolcano north of Toba, Sinabung, shows strong geochemical kinship with Toba, and zircons from recent eruption products suggest Toba's climactic magma reservoir extends beneath Sinabung and is being tapped during eruptions. PMID:28508876</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.S11A1138S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.S11A1138S"><span>A Comparison of Historic <span class="hlt">Caldera</span>-Forming Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stix, J.</p> <p>2002-12-01</p> <p>Recent field, experimental, and theoretical studies of <span class="hlt">calderas</span> have advanced our understanding of how <span class="hlt">calderas</span> form. With this in mind, I compare and contrast the styles and mechanisms of <span class="hlt">caldera</span> development for five historic events: Katmai 1912, Kilauea 1924, Fernandina 1968, Pinatubo 1991, and Miyakejima 2000. As well as affording an opportunity to compare felsic and mafic systems, these examples allow us to identify systematic similarities and differences during the process of <span class="hlt">caldera</span> formation. Critical questions include the following. (1) What are durations of <span class="hlt">caldera</span> formation, as well as precursory signals and triggering mechanisms? (2) Why is there frequently a mismatch between <span class="hlt">caldera</span> volumes at the surface and magma volume changes in the subsurface? (3) What are the relative proportions of erupted magma vs. magma which is drained and/or transported laterally in the subsurface? (4) How much magma is displaced, either by eruption or by drainage, before a <span class="hlt">caldera</span> starts forming at the surface? (5) Does <span class="hlt">caldera</span> subsidence occur en masse, incrementally, or somewhere between these two extremes of behavior? (6) Does subsidence of the <span class="hlt">caldera</span> block help magma to be evacuated from the chamber, or is the subsidence process a passive response to magma withdrawal by other means? In addition to addressing the above questions, I will discuss how <span class="hlt">caldera</span> formation influences the development of "open" and "closed" magmatic systems. Finally, I will discuss the problems of scaling, as the historic examples discussed here are 1-3 orders of magnitude smaller than large-scale <span class="hlt">caldera</span>-forming ignimbrite eruptions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018518','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018518"><span>Kulshan <span class="hlt">caldera</span>: A Quaternary subglacial <span class="hlt">caldera</span> in the North Cascades, Washington</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hildreth, W.</p> <p>1996-01-01</p> <p><span class="hlt">Calderas</span> that collapse during large pyroclastic eruptions are anomalously rare in the Cascade arc. Recognition of the early Pleistocene 4.5 ?? 8 km Kulshan <span class="hlt">caldera</span>, filled with rhyodacite ignimbrite at the northeast foot of Mount Baker, brings to only three the Quaternary <span class="hlt">calderas</span> identified in the Cascades. A near-vertical ring fault cut in basement rocks of the North Cascades encloses 30 km2 of intracaldera ignimbrite (and intermixed collapse breccia) >1 km thick but with no floor exposed. The Lake Tapps tephra in the Puget lowland is the correlative fallout; 200 km from the source, it is as thick as 30 cm. Features of the distal ash fall and the intracaldera tuff suggest large-scale phreatomagmatism during an eruption that may have started subglacially. Several advances of the Cordilleran ice sheet subsequently obliterated the topographic rim, removed every vestige of extracaldera ignimbrite and proximal fallout, and stripped any precaldera extrusive rocks - the former existence of which is suggested only by a few silicic intrusions that cut the circumcaldera basement. Although the <span class="hlt">caldera</span> is not structurally resurgent, several early intracaldera rhyodacite lavas intrude and rest directly on ignimbrite or on ashy <span class="hlt">caldera</span>-lake sediments reworked from the eruption products. Subsidence areas, pumice compositions, and volumes of magma erupted (>50 km3) are similar for the Kulshan, Rockland, and Crater Lake (Mazama) events, the three Quaternary <span class="hlt">caldera</span>-forming eruptions now recognized in the Cascades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93X.298S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93X.298S"><span>Italian super-eruption larger than thought</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schultz, Colin</p> <p>2012-07-01</p> <p>Recent research suggested that the super-eruption of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> volcano in southern Italy about 40,000 years ago may have played a part in wiping out, or forcing the migration of, the Neanderthal and modern human populations in the eastern Mediterranean regions that were covered in ash. Now a new modeling study by Costa et al. suggests that this eruption may have been even larger than previously thought. This <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> eruption produced a widespread ash layer known as Campanian Ignimbrite (CI). Using ash thickness measurements collected at 115 sites and a three-dimensional ash dispersal model, the researchers found that the CI super-eruption would have spread 250-300 cubic kilometers of ash across a 3.7-million-square kilometer region—2 to 3 times previous ash volume estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989BVol...52...97H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989BVol...52...97H"><span>The Christmas Mountains <span class="hlt">caldera</span> complex, Trans-Pecos Texas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henry, Christopher D.; Price, Jonathan G.</p> <p>1989-12-01</p> <p>The Christmas Mountains <span class="hlt">caldera</span> complex developed approximately 42 Ma ago over an elliptical (8×5 km) laccolithic dome that formed during emplacement of the <span class="hlt">caldera</span> magma body. Rocks of the <span class="hlt">caldera</span> complex consist of tuffs, lavas, and volcaniclastic deposits, divided into five sequences. Three of the sequences contain major ash-flow tuffs whose eruption led to collapse of four <span class="hlt">calderas</span>, all 1 1.5 km in diameter, over the dome. The oldest <span class="hlt">caldera</span>-related rocks are sparsely porphyritic, rhyolitic, air-fall and ash-flow tuffs that record formation and collapse of a Plinian-type eruption column. Eruption of these tuffs induced collapse of a wedge along the western margin of the dome. A second, more abundantly porphyritic tuff led to collapse of a second <span class="hlt">caldera</span> that partly overlapped the first. The last major eruptions were abundantly porphyritic, peralkaline quartz-trachyte ash-flow tuffs that ponded within two <span class="hlt">calderas</span> over the crest of the dome. The tuffs are interbedded with coarse breccias that resulted from failure of the <span class="hlt">caldera</span> walls. The Christmas Mountains <span class="hlt">caldera</span> complex and two similar structures in Trans-Pecos Texas constitute a newly recognized <span class="hlt">caldera</span> type, here termed a laccocaldera. They differ from more conventional <span class="hlt">calderas</span> by having developed over thin laccolithic magma chambers rather than more deep-seated bodies, by their extreme precaldera doming and by their small size. However, they are similar to other <span class="hlt">calderas</span> in having initial Plinian-type air-fall eruption followed by column collapse and ash-flow generation, multiple cycles of eruption, contemporaneous eruption and collapse, apparent pistonlike subsidence of the <span class="hlt">calderas</span>, and compositional zoning within the magma chamber. Laccocalderas could occur else-where, particularly in alkalic magma belts in areas of undeformed sedimentary rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S53A2810H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S53A2810H"><span>Valles <span class="hlt">Caldera</span>, New Mexico Microearthquakes: Improved Detection and Location with Expanded <span class="hlt">Caldera</span> Station Coverage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>House, L. S.; Roberts, P. M.; Ten Cate, J. A.</p> <p>2016-12-01</p> <p>The Los Alamos Seismic Network (LASN) has operated for 44 years, providing data to locate more than 2,500 earthquakes in north-central New Mexico. Roughly 1-2 earthquakes are detected and located per month within about 150 km of Los Alamos, a total of over 900 from 1973 to present. LASN's primary purpose is to monitor seismicity close to the Los Alamos National Laboratory (LANL) for seismic hazards; monitoring seismicity associated with the nearby Valles <span class="hlt">Caldera</span> is secondary. Until 2010 the network comprised only 7 stations, all near LANL or in the nearby Jemez Mountains. Just one station (PER, installed in 1998) was close enough to Valles <span class="hlt">Caldera</span> to be able to detect microearthquakes located in or near the <span class="hlt">caldera</span>. An initial study of the data from station PER between 1998 and 2002 identified and located 13 events with magnitudes less than 0.5 using the single-station hodogram technique. Those events were all located south of the <span class="hlt">caldera</span> within a few kilometers of PER. Recently, two new digital broadband stations were installed inside the <span class="hlt">caldera</span>, one on a northeastern ring-fracture dome, station CDAB, and the other on a northwestern dome, station SAMT. Also, station PER was upgraded with digital broadband instrumentation. Thus, LASN now can detect and record microearthquakes as small as magnitude -1.5 near the <span class="hlt">caldera</span>, and they can be located using arrival times at multiple stations. Several recent events located near station SAMT on the <span class="hlt">caldera</span>'s ring fracture are the first that have been seen in that area. Additional events were recorded (by all three stations) and located in the area south of the <span class="hlt">caldera</span> where the earlier hodogram-only events were located. These new multi-station event recordings allow a more quantitative assessment of the uncertainties in the initial single-station hodogram locations. Each event is located using multiple arrival times as well as the hodogram method at as many as three stations. Thus, improvements can be made to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ngmdb.usgs.gov/Prodesc/proddesc_70020.htm','USGSPUBS'); return false;" href="http://ngmdb.usgs.gov/Prodesc/proddesc_70020.htm"><span>The Long Valley <span class="hlt">Caldera</span> GIS database</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Battaglia, Maurizio; Williams, M.J.; Venezky, D.Y.; Hill, D.P.; Langbein, J.O.; Farrar, C.D.; Howle, J.F.; Sneed, M.; Segall, P.</p> <p>2003-01-01</p> <p>This database provides an overview of the studies being conducted by the Long Valley Observatory in eastern California from 1975 to 2001. The database includes geologic, monitoring, and topographic datasets related to Long Valley <span class="hlt">caldera</span>. The CD-ROM contains a scan of the original geologic map of the Long Valley region by R. Bailey. Real-time data of the current activity of the <span class="hlt">caldera</span> (including earthquakes, ground deformation and the release of volcanic gas), information about volcanic hazards and the USGS response plan are available online at the Long Valley observatory web page (http://lvo.wr.usgs.gov). If you have any comments or questions about this database, please contact the Scientist in Charge of the Long Valley observatory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982BVol...45...63V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982BVol...45...63V"><span>Geochemistry of Los Humeros <span class="hlt">Caldera</span>, Puebla, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verma, S. P.; Lopez, M.</p> <p>1982-03-01</p> <p>Geochemistry of Pliocene to recent volcanic rocks from Los Humeros <span class="hlt">caldera</span> (19°30' N - 19°50' N and 97°15° W - 97°35' W) in East-Central mexico is described. The volcanic rocks from this area seem to represent both alkali and high-alumina basalt series, or both calcalkaline and high-K calc-alkaline sequences. The available bulk-chemical analyses (23 this study and 18 from unpublished literature) show that the entire sequence of rocks from basalts to rhyolites are present in this area. Different degrees of partial melting of the source region followed by extensive shallow-level crystal differentiation seem to have taken place before most volcanic eruptions. These processes are perhaps the most important mechanisms for magma genesis in Los Humeros <span class="hlt">caldera</span>. Geophysical studies in this area are not sufficient and more detailed geophysical surveys and a better geological interpretation are needed in order to delimit the underlying magma chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/fs/2014/3056/pdf/fs2014-3056.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/fs/2014/3056/pdf/fs2014-3056.pdf"><span>California's restless giant: the Long Valley <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae</p> <p>2014-01-01</p> <p>Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley <span class="hlt">Caldera</span> had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17842285','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17842285"><span>Buried <span class="hlt">caldera</span> of mauna kea volcano, hawaii.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Porter, S C</p> <p>1972-03-31</p> <p>An elliptical <span class="hlt">caldera</span> (2.1 by 2.8 kilometers) at the summit of Mauna Kea volcano is inferred to lie buried beneath hawaiite lava flows and pyroclastic cones at an altitude of approximately 3850 meters. Stratigraphic relationships indicate that hawaiite eruptions began before a pre-Wisconsin period of ice-cap glaciation and that the crest of the mountain attained its present altitude and gross form during a glaciation of probable Early Wisconsin age.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6524236','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6524236"><span>Core lithology, Valles <span class="hlt">caldera</span> No. 1, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gardner, J.N.; Goff, F.; Goff, S.; Maassen, L.; Mathews, K.; Wachs, D.; Wilson, D.</p> <p>1987-04-01</p> <p>Vallas <span class="hlt">caldera</span> No. 1 (VC-1) is the first Continental Scientific Drilling Program research core hole in the Vallas <span class="hlt">caldera</span> and the first continuously cored hole in the region. The hole penetrated 298 m of moat volcanics and <span class="hlt">caldera</span>-fill ignimbrites, 35 m of volcaniclastic breccia, and 523 m of Paleozoic carbonates, sandstones, and shales with over 95% core recovery. The primary research objectives included coring through the youngest rhyolite flow within the <span class="hlt">caldera</span>; obtaining structural and stratigraphic information near the intersection of the ring-fracture zone and the pre-<span class="hlt">caldera</span> Jemez fault zone; and penetrating a high-temperature hydrothermal outflow plume near its source. This report presents a compilation of lithologic and geophysical logs and photographs of core that were collected while drilling VC-1. It is intended to be a reference tool for researchers interested in <span class="hlt">caldera</span> processes and associated geologic phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V33E2833C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V33E2833C"><span><span class="hlt">Caldera</span>-Fill Sediments at Toba <span class="hlt">Caldera</span>, Sumatra, Indonesia: A Field Reconnaissance Report</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chesner, C. A.; Barbee, O. A.; Lesmana, Z.; Nasution, A.</p> <p>2013-12-01</p> <p>The 74 ka Toba <span class="hlt">Caldera</span> in northern Sumatra offers a unique opportunity to study <span class="hlt">caldera</span>-fill sedimentation and its implications on the dynamic post-collapse history of Earth's largest Quaternary resurgent <span class="hlt">caldera</span>. Although the complete 74,000 year sedimentation record is hidden beneath Lake Toba, a significant portion (~20-74 ka) of the post-<span class="hlt">caldera</span> sedimentary sequence has been uplifted above lake level and is exposed on the 45 x 18 km Samosir Island resurgent dome. This extensive sedimentary record, over 100 m thick in places, is exposed by stream incision, and in resurgent dome fault scarps. Reconnaissance mapping and sampling of the sedimentary veneer covering Samosir Island was conducted in 2012-2013 to supplement recent sub-bottom seismic reflection profiling (chirp sonar) of the younger sediments and provide the basis for a more detailed <span class="hlt">caldera</span>-fill sedimentation study at Toba. Our preliminary mapping indicates that distinct lacustrine and fluvial sedimentary sequences occur on Samosir Island. The lacustrine sequence dominates the surface exposures across the island and consists of interbedded clays, silts, sands, and diatomites. Different depositional environments and processes are suggested by regional variations in the componentry (i.e. abundance of diatoms, pumice clasts, reworked lake sediment clasts, rafted pumice blocks, etc.), but no significant ash-beds have been identified. An underlying coarse-grained indurated fluvial sequence is exposed in deeply incised drainages and fault scarps. This sequence consists mostly of coarse oxidized sands in eastern Samosir (approximately in the center of the <span class="hlt">caldera</span>) that thicken and become coarser in western Samosir towards the <span class="hlt">caldera</span> wall, where breccias and debris flows are also common. Blocks and boulders up to several meters in diameter derived from the basement rocks in the western <span class="hlt">caldera</span> walls suggest a wedge of alluvial sediments formed before the lake reached its maximum level. Samples have been</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V31B3028I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31B3028I"><span>Eruptive History of Ikeda <span class="hlt">Caldera</span>, Southern Kyushu, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inakura, H.; Naruo, H.; Okuno, M.; Kobayashi, T.; Tamura, T.</p> <p>2015-12-01</p> <p>Ikeda <span class="hlt">caldera</span> is a small-scale <span class="hlt">caldera</span> (about 4 km in diameter), located in the southern tip of the Satsuma Peninsula, southern Kyushu, Japan. The information on the onset of the <span class="hlt">caldera</span>-forming eruption is gone due to the catastrophic eruption, but Ikeda <span class="hlt">caldera</span> is a relatively small-scale eruption that the information before the eruption may have been conserved. We conducted a geological research to understand the eruptive history of Ikeda <span class="hlt">caldera</span>, including a study of the processes leading to the catastrophic eruption. Pre-<span class="hlt">caldera</span> activity began at about 20 cal kBP by Iwamoto ash and the effusion of Senta lava, which may have similar composition as the <span class="hlt">caldera</span>-forming eruption. The <span class="hlt">caldera</span>-forming eruption began at 6.4 cal kBP with a phreatic explosion that produced the Ikezaki tephra. The phreatic eruption was followed by Osagari scoria, Mizusako scoria and Ikeda pumice plinian eruption. During the climactic stage, Ikeda ignimbrite was erupted and reclaimed the coastal area at that time, and formed the ignimbrite plateau along the coast. Immediately after this event, four maars were formed to the southeast of the <span class="hlt">caldera</span>. Yamagawa maar, which is the largest and is located at the southeastern end of the fissure vent, erupted pumiceous base surge (Yamagawa base surge), but other maars ejected small amount of accidental materials. During the late stage of the Ikeda eruption, phreatomagmatic eruption occurred at the bottom of the <span class="hlt">caldera</span> floor, and erupted the Ikedako ash which covered a wide area. The Central lava dome was generated at the late stage of this eruption. After Ikedako ash deposition, secondary explosion of Ikeda ignimbrite occurred mainly along the coastal area, generating small-scale base surge deposits. About two thousand years after the <span class="hlt">caldera</span>-forming eruption at 4.8 cal kBP, new magmatic activity began on the margin of the <span class="hlt">caldera</span> rim, and generated Nabeshimadake lava dome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JVGR..202..127G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JVGR..202..127G"><span>Glacial influence on <span class="hlt">caldera</span>-forming eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geyer, Adelina; Bindeman, Ilya</p> <p>2011-04-01</p> <p>It has been suggested that deglaciations have influenced volcanism in several areas around the world increasing productivity of mantle melting and eruptions from crustal magma chambers. However, the connection between glaciations and increased volcanism is not straightforward. Investigation of Ar-Ar, U-Pb, and 14C ages of <span class="hlt">caldera</span>-forming eruptions for the past million years in the glaciated arc of Kamchatka has lead to the observation that the majority of large-volume ignimbrites, which are associated with the morphologically preserved <span class="hlt">calderas</span>, correspond in time with "maximum glacial" conditions for the past several glacial cycles. In the field, the main proof is related to the fact that glaciated multi-<span class="hlt">caldera</span> volcanoes hosted thick glacial ice caps. Additional evidence comes from clustering Kamchatka-derived marine ash layers with glacial moraines in DSDP cores. Here we present a set of new results from numerical modelling using the Finite Element Method that investigate how the glacial load dynamic may affect the conditions for ring-fault formation in such glaciated multi-<span class="hlt">caldera</span> volcanoes. Different scenarios were simulated by varying: (1) the thickness and asymmetric distribution of the existing ice cap, (2) the depth and size of the magmatic reservoir responsible for the subsequent collapse event, (3) the thickness and mechanical properties of the roof rock due to the alteration by hydrothermal fluids, (4) the existence of a deeper and wider magmatic reservoir and (5) possible gravitational failure triggered, in part, by subglacial rock mass build up and hydrothermal alteration. The results obtained indicate that: (1) Any ice cap plays against ring fault formation; (2) Asymmetric distribution of ice may favour the initiation of trap-door type collapse <span class="hlt">calderas</span>; (3) Glacial erosion of part of volcanic edifice or interglacial edifice failure may facilitate subsequent ring fault formation; (4) hydrothermal system under an ice cap may lead to a quite effective</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5467724','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5467724"><span><span class="hlt">Caldera</span> processes and magma-hydrothermal systems continental scientific drilling program: thermal regimes, Valles <span class="hlt">caldera</span> research, scientific and management plan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goff, F.; Nielson, D.L.</p> <p>1986-05-01</p> <p>Long-range core-drilling operations and initial scientific investigations are described for four sites in the Valles <span class="hlt">caldera</span>, New Mexico. The plan concentrates on the period 1986 to 1993 and has six primary objectives: (1) study the origin, evolution, physical/chemical dynamics of the vapor-dominated portion of the Valles geothermal system; (2) investigate the characteristics of <span class="hlt">caldera</span> fill and mechanisms of <span class="hlt">caldera</span> collapse and resurgence; (3) determine the physical/chemical conditions in the heat transfer zone between crystallizing plutons and the hydrothermal system; (4) study the mechanism of ore deposition in the <span class="hlt">caldera</span> environment; (5) develop and test high-temperature drilling techniques and logging tools; and (6) evaluate the geothermal resource within a large silicic <span class="hlt">caldera</span>. Core holes VC-2a (500 m) and VC-2b (2000 m) are planned in the Sulphur Springs area; these core holes will probe the vapor-dominated zone, the underlying hot-water-dominated zone, the boiling interface and probable ore deposition between the two zones, and the deep structure and stratigraphy along the western part of the Valles <span class="hlt">caldera</span> fracture zone and resurgent dome. Core hole VC-3 will involve reopening existing well Baca number12 and deepening it from 3.2 km (present total depth) to 5.5 km, this core hole will penetrate the deep-crystallized silicic pluton, investigate conductive heat transfer in that zone, and study the evolution of the central resurgent dome. Core hole VC-4 is designed to penetrate deep into the presumably thick <span class="hlt">caldera</span> fill in eastern Valles <span class="hlt">caldera</span> and examine the relationship between <span class="hlt">caldera</span> formation, sedimentation, tectonics, and volcanism. Core hole VC-5 is to test structure, stratigraphy, and magmatic evolution of pre-Valles <span class="hlt">caldera</span> rocks, their relations to Valles <span class="hlt">caldera</span>, and the influences of regional structure on volcanism and <span class="hlt">caldera</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V51F..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V51F..08H"><span>Yellowstone and Long Valley - A Comparison of Two Restless <span class="hlt">Calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, D. P.; Smith, R. B.</p> <p>2007-12-01</p> <p>Three large, silicic <span class="hlt">calderas</span> in the conterminous United States have explosively erupted volumes > 300 km3 within in the last 2 million years -- Yellowstone <span class="hlt">caldera</span> (Wyoming) Long Valley <span class="hlt">caldera</span> (California) and the Vallez <span class="hlt">caldera</span> (New Mexico) all located in extensional tectonic environments. All have shown varying levels of historic unrest. Pronounced unrest episodes at Yellowstone and Long Valley <span class="hlt">calderas</span> over the past three decades stimulated extensive research on these two closely monitored <span class="hlt">calderas</span>, and we explore some emerging similarities and differences. Yellowstone <span class="hlt">caldera</span> is underlain by a long-lived (> 17 my) upper-mantle hot-spot that has fed a series of <span class="hlt">caldera</span>-forming, extending to the southwest across southern Idaho to central Oregon including three <span class="hlt">caldera</span>-forming eruptions from the Yellowstone <span class="hlt">caldera</span> system in the last 2 my, the most recent at 600,000 ybp. It is marked by relatively low density and low seismic velocities extending to depths of at least 400 km and a regional topographic swell with elevations exceeding 2000 m. The extensive Yellowstone hydrothermal system has a thermal output of 5 GW. The most recent magmatic eruption dated at 70,000 ybp. By comparison, Long Valley <span class="hlt">caldera</span> is underlain by a relatively modest "hot-spot", the locus of which appears to be influenced by a dilatational jog between the dextral Eastern California Shear Zone and the Walker Lane and westward delamination of the dense lithospheric root of the adjacent Sierra Nevada. The Long Valley system has fed multiple eruptions of over the past 4 my and a single <span class="hlt">caldera</span>-forming eruption at 760,000 ybp. It is marked by a limited topographic swell but with the elevation of the <span class="hlt">caldera</span> floor and adjacent basins comparable to the 2000-plus m elevation of the Yellowstone swell. Long Valley <span class="hlt">caldera</span> hydrothermal system has a thermal output of 0.3 GW (including a 40 MW geothermal power plant). The most recent eruptions from the Long Valley <span class="hlt">Caldera</span>- Mono Domes volcanic field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BVol...74.1833K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BVol...74.1833K"><span><span class="hlt">Caldera</span> resurgence during magma replenishment and rejuvenation at Valles and Lake City <span class="hlt">calderas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kennedy, Ben; Wilcock, Jack; Stix, John</p> <p>2012-10-01</p> <p>A key question in volcanology is the driving mechanisms of resurgence at active, recently active, and ancient <span class="hlt">calderas</span>. Valles <span class="hlt">caldera</span> in New Mexico and Lake City <span class="hlt">caldera</span> in Colorado are well-studied resurgent structures which provide three crucial clues for understanding the resurgence process. (1) Within the limits of 40Ar/39Ar dating techniques, resurgence and hydrothermal alteration at both <span class="hlt">calderas</span> occurred very quickly after the <span class="hlt">caldera</span>-forming eruptions (tens of thousands of years or less). (2) Immediately before and during resurgence, dacite magma was intruded and/or erupted into each system; this magma is chemically distinct from rhyolite magma which was resident in each system. (3) At least 1 km of structural uplift occurred along regional and subsidence faults which were closely associated with shallow intrusions or lava domes of dacite magma. These observations demonstrate that resurgence at these two volcanoes is temporally linked to <span class="hlt">caldera</span> subsidence, with the upward migration of dacite magma as the driver of resurgence. Recharge of dacite magma occurs as a response to loss of lithostatic load during the <span class="hlt">caldera</span>-forming eruption. Flow of dacite into the shallow magmatic system is facilitated by regional fault systems which provide pathways for magma ascent. Once the dacite enters the system, it is able to heat, remobilize, and mingle with residual crystal-rich rhyolite remaining in the shallow magma chamber. Dacite and remobilized rhyolite rise buoyantly to form laccoliths by lifting the chamber roof and producing surface resurgent uplift. The resurgent deformation caused by magma ascent fractures the chamber roof, increasing its structural permeability and allowing both rhyolite and dacite magmas to intrude and/or erupt together. This sequence of events also promotes the development of magmatic-hydrothermal systems and ore deposits. Injection of dacite magma into the shallow rhyolite magma chamber provides a source of heat and magmatic volatiles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V23G..04K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V23G..04K"><span>Magma mixing during <span class="hlt">caldera</span> forming eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kennedy, B.; Jellinek, M.; Stix, J.</p> <p>2006-12-01</p> <p>During explosive <span class="hlt">caldera</span>-forming eruptions magma erupts through a ring dyke. Flow is driven, in part, by foundering of a magma chamber roof into underlying buoyant magma. One intriguing and poorly understood characteristic of deposits from <span class="hlt">calderas</span> is that bulk ignimbrite, pumices, and crystals can show complex stratigraphic zonation. We propose that zonation patterns can be explained by different, and temporally evolving subsidence styles, and that the geometry imposed by subsidence can affect flow and cause mixing in the chamber and ring dyke. We use two series of laboratory experiments to investigate aspects of the mixing properties of flow in the chamber and ring dike during <span class="hlt">caldera</span> collapse. In the first series, cylindrical blocks of height, h, and diameter, d, are released into circular analog magma chambers of diameter D and height H, containing buoyant fluids with viscosities that we vary. Subsidence occurs as a result of flow through the annular gap (ring dike) between the block and the wall of the surrounding tank of width, w = D-d. Three dimensionless parameters characterize the nature and evolution of the subsidence, and the resulting flow: A Reynolds number, Re, a tilt number, T = w/h and a subsidence number, S = w/H. Whereas Re indicates the importance of inertia for flow and mixing, T and S are geometric parameters that govern the extent of roof tilting, the spatial variation in w during collapse and the wavelength and structure of fluid motions. On the basis of field observations and theoretical arguments we fix T ≍ 0.14 and characterize subsidence and the corresponding flow over a wide range of Re - S parameter space appropriate to silicic <span class="hlt">caldera</span> systems. Where S < 2 and Re < 103 the roof can rotate or tilt as it sinks and a spectrum of fluid mechanical behavior within the ring dike are observed. The combination of roof rotation and tilting drives unsteady, 3D overturning motions within the ring dike that are inferred to cause extensive mixing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JVGR..194...15P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JVGR..194...15P"><span>The Cerro Aguas Calientes <span class="hlt">caldera</span>, NW Argentina: An example of a tectonically controlled, polygenetic collapse <span class="hlt">caldera</span>, and its regional significance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrinovic, I. A.; Martí, J.; Aguirre-Díaz, G. J.; Guzmán, S.; Geyer, A.; Paz, N. Salado</p> <p>2010-07-01</p> <p>Polygenetic, silicic collapse <span class="hlt">calderas</span> are common in the central Andes. Here we describe in detail the Cerro Aguas Calientes <span class="hlt">caldera</span> in NW Argentina, which comprises two <span class="hlt">caldera</span>-forming episodes that occurred at 17.15 Ma and 10.3 Ma. We analyse the significance of its structural setting, composition, size and the subsidence style of both <span class="hlt">caldera</span> episodes. We find that the <span class="hlt">caldera</span> eruptions had a tectonic trigger. In both cases, an homogeneous dacitic crystal-rich (>60 vol.% of crystals) reservoir of batholithic size became unstable due to the effect of increasing regional transpression, which favoured local dilation through minor strike-slip faults from which ring faults nucleated and permitted <span class="hlt">caldera</span> collapse. Both <span class="hlt">calderas</span> are similar in shape, location and products. The 17.15 Ma <span class="hlt">caldera</span> has an elliptical shape (17 × 14 km) elongated in a N30° trend; both intracaldera and extracaldera ignimbrites covered an area of around 620 km 2 with a minimum volume estimate of 140 km 3 (DRE). The 10.3 Ma episode generated another elliptical <span class="hlt">caldera</span> (19 × 14 km), with the same orientation as the previous one, from which intracaldera and outflow ignimbrites covered a total area of about 1700 km 2, representing a minimum eruption volume of 350 km 3(DRE). In this paper we discuss the significance of the Cerro Aguas Calientes <span class="hlt">caldera</span> in comparison with other well known examples from the central Andes in terms of tectonic setting, eruption mechanisms, and volumes of related ignimbrites. We suggest that our kinematic model is a common volcano-tectonic scenario during the Cenozoic in the Puna and Altiplano, which may be applied to explain the origin of other large <span class="hlt">calderas</span> in the same region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.3131P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.3131P"><span>The Cerro Aguas Calientes <span class="hlt">caldera</span>, NW Argentina: an example of a tectonically controlled, polygenetic, collapse <span class="hlt">caldera</span>, and its regional significance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrinovic, Ivan A.; Martí, Joan; Aguirre-Diaz, Gerardo J.; Guzmán, Silvina R.; Geyer, Adelina; Grosse, Pablo; Salado Paz, Natalia</p> <p>2010-05-01</p> <p>Polygenetic, silicic collapse <span class="hlt">calderas</span> such as Cerro Galán, Pastos Grandes, La Pacana, Vilama, Negra Muerta, Farallón Negro, Cerro Guacha, among others are common in the central Andes. Here we describe in detail the Cerro Aguas Calientes <span class="hlt">caldera</span> in NW Argentina, which comprises two <span class="hlt">caldera</span>-forming episodes occurred at 17.15 Ma and 10.3 Ma, respectively. We analyse the significance of its structural setting, composition, size and the subsidence style of both <span class="hlt">caldera</span> episodes. Our results reveal that the <span class="hlt">caldera</span> eruptions had a tectonic trigger. In both cases, an homogeneous dacitic crystal-rich (>60 vol. % of crystals) reservoir of batholitic size became unstable due to the effect of increasing regional transpression, favouring local dilation throughout minor strike slip faults from which ring faults nucleated and permitted <span class="hlt">caldera</span> collapse. Both episodes are similar in shape, location and products of the resulting <span class="hlt">calderas</span>. The 17.15 Ma <span class="hlt">caldera</span> has an elliptical shape (17 × 14 km) and is elongated in a N30° trend; both intracaldera and extracaldera ignimbrites covered an area of around 620 km2 with a minimum volume estimate of 138 km3 (DRE). The 10.3 Ma episode generated another elliptical <span class="hlt">caldera</span> (19 ×14 km), with the same orientation as the previous one, from which intracaldera and outflow ignimbrites covered a total area of about 1,700 km2, representing a minimum eruption volume of 341 km3 (DRE). In this work we discuss the significance of the Cerro Aguas Calientes <span class="hlt">caldera</span> in comparison with other well known examples from the central Andes in terms of tectonic setting, eruption mechanisms, and volumes of related ignimbrites. We suggest that our kinematic model is a common volcano-tectonic scenario during the Cenozoic in the Puna and Altiplano, which may be applied to explain the origin of other large <span class="hlt">calderas</span> in the same region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/28338','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/28338"><span>Chapter 1. Valles <span class="hlt">Caldera</span> National Preserve land use history</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Kurt F. Anschuetz</p> <p>2007-01-01</p> <p>The land use history of the Valles <span class="hlt">Caldera</span> National Preserve (VCNP) extends back over thousands of years. Few known archaeological properties in the Valles <span class="hlt">Caldera</span> date to the Paleoindian period (10000/9500–5500 B.C.). These finds include the recent discovery, during ongoing archaeological studies (Dr. Bob Parmeter, personal communication, VCNP, Los Alamos, 2005), of...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V31G..03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31G..03T"><span>Setting A Stopwatch for Post-<span class="hlt">Caldera</span> Effusive Rhyolite Eruptions at Yellowstone <span class="hlt">caldera</span>, Wyoming</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Till, C. B.; Vazquez, J. A.; Boyce, J. W.</p> <p>2015-12-01</p> <p>Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at <span class="hlt">calderas</span> with protracted histories of eruption and unrest such as Yellowstone <span class="hlt">caldera</span> (Wyoming), Long Valley <span class="hlt">caldera</span> (California), and Valles <span class="hlt">caldera</span> (New Mexico) in the United States. Although orders of magnitude smaller in volume than rare <span class="hlt">caldera</span>-forming supereruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear, particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses trace element diffusion in sanidine crystals measured at nanometer-scale with NanoSIMS to reveal that rejuvenation of a near-solidus or subsolidus silicic intrusion occurred within ~10 months following a protracted period (220 k.y.) of volcanic repose, and resulted in effusion of ~3 km3 of high-silica rhyolite lava at the onset of Yellowstone's last volcanic interval. In addition we find that the frequently made assumption in geospeedometry of a step-function initial condition can be inaccurate despite petrographic evidence for resorption, and can be addressed by interrogating diffusion time scale concordance between multiple trace elements that are geochemically similar. The results of this study reveal that a sufficiently energetic rejuvenation of Yellowstone's shallow crystal-melt mush and/or hydrothermally altered wall rock could lead to an effusive eruption within months. Fortunately, any significant rejuvenation of the reservoir is likely to be associated with deformation or seismicity and identifiable by geophysical monitoring.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.V43A..04A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.V43A..04A"><span>The graben <span class="hlt">caldera</span> of Guanajuato, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Diaz, G. J.; Tristán-González, M.; Labarthe-Hernández, G.; Marti, J.</p> <p>2013-05-01</p> <p>Guanajuato has been an important gold and silver mineral district of Mexico since the 16th century until Present. Famous mines such as Rayas, La Valenciana and El Cubo, are part of this important mining development. Stratigraphy and structures are well known, and major faults and vein systems are precisely mapped. The series include a Mesozoic metamorphosed volcano-sedimentary sequence interpreted as a tectonically accreted terrane during Early Cretaceous subduction; a >1000 m thick red beds sequence, apparently Eocene and interpreted originally as molasses posterior to K/T Laramide orogeny, but more probably fanglomerates filling a graben formed during mid-Tertiary extension; an Eocene-Miocene volcanic sequence that accumulated in this tectonic basin and the surrounding area, including andesitic lavas, silicic ignimbrites and surge deposits, and rhyolitic domes. Pyroclastic rocks have not been studied with a volcanological approach, with the purpose of understanding the physical volcanic processes that formed them. Randall (1994) suggested a <span class="hlt">caldera</span> source for some of them. Our purpose is to describe the volcanic processes involved in the mid-Tertiary units of Guanajuato. There are dacitic and andesitic lavas that were apparently contemporaneous with deposition of the Red Conglomerate of Guanajuato. The ignimbrites correspond to the Sierra Madre Occidental volcanic province. These units were originated as two main pyroclastic densety currents sequences that formed the Loseros-Bufa and the Calderones formations. The former is rhyolitic and the later andesitic-dacitic. Loseros is composed of a series of thin-bedded to laminated pyroclastic surge deposits in continuous and concordant contact with overlying Bufa massive ignimbrite. Bufa ignimbrite is partly welded, with columnar jointing, completely devitrified, and highly silicified by post-deposition hydrothermalism and/or vapor phase alteration. Co-ignimbrite lithic lag breccias are observed at several sites in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JVGR..111..203A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JVGR..111..203A"><span>The Amazcala <span class="hlt">caldera</span>, Queretaro, Mexico. Geology and geochronology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Díaz, Gerardo J.; López-Martínez, Margarita</p> <p>2001-11-01</p> <p>The Amazcala <span class="hlt">caldera</span> is located 30 km NE of Querétaro City, near Amazcala, state of Querétaro. This <span class="hlt">caldera</span> is the northernmost <span class="hlt">caldera</span> within the central sector of the Mexican Volcanic Belt (MVB). It has a 11×14 km 2 elliptical shape, and was formed 7.3-6.6 Ma ago. All <span class="hlt">caldera</span> products are rhyolites. The oldest <span class="hlt">caldera</span> unit, the Ezequiel Montes pumice (EMP), is a widespread pumice fallout emplaced around 7.3 Ma ago. An isopach map of the EMP shows two dispersal axes, oriented to the SW and SE with respect to the <span class="hlt">caldera</span>. The EMP is 5 m thick 40 km to the SW and 35 km to the SE of the <span class="hlt">caldera</span>. An isopleth map of the EMP shows that pumice fragments increase in size toward the <span class="hlt">caldera</span>, from 1 cm at 40 km to 25 cm near the <span class="hlt">caldera</span> rim. The EMP is a regional stratigraphic marker. The Colón ignimbrite, dated at 7.3±0.5 Ma, is stratigraphically above the EMP. It consists of several ash-flow units interbedded with minor pumice fall lapilli and ash, with a minimum thickness of about 80 m at Colón. The <span class="hlt">caldera</span> rim is occupied by several rhyolite lava domes and flows, some of which extend 10 km from the rim. These domes contain parts of fresh, aphyric obsidian. The last <span class="hlt">caldera</span> event is an intracaldera rhyolitic dome near the NE rim at about 6.6 Ma. The dome is 4×2 km 2 and is elongated in the NE direction. The Amazcala <span class="hlt">caldera</span> is 480 km from the Middle America Trench and represents the farthest inland <span class="hlt">caldera</span> in the central sector of the MVB. Its age of 7.3-6.6 Ma indicates that it is the oldest <span class="hlt">caldera</span> of the MVB so far reported. This confirms the general view that the volcanic activity of the MVB initiated at its northern margin, and then migrated southward in time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JVGR..181..185G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JVGR..181..185G"><span>Stress fields controlling the formation of nested and overlapping <span class="hlt">calderas</span>: Implications for the understanding of <span class="hlt">caldera</span> unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geyer, A.; Martí, J.</p> <p>2009-04-01</p> <p>Commonly, the formation of a collapse <span class="hlt">caldera</span> does not necessarily imply the end of the volcanic activity in the area. In many cases, successive <span class="hlt">calderas</span> may form close to the previous collapse depression or intersecting it leading to overlapping collapse structures. Occasionally, subsequent <span class="hlt">caldera</span> collapses may take place at the interior of the first <span class="hlt">caldera</span> creating nested collapse structures. During the last years several authors have investigated numerically how the stress field around magma chambers may favour the formation of collapse <span class="hlt">calderas</span> assuming that the host rock surrounding the magmatic reservoir behaves as a linear elastic homogeneous medium. The numerical models presented in this work study how a <span class="hlt">caldera</span> collapse may modify the stress field of a volcanic area and hence the conditions for the formation of future collapse <span class="hlt">calderas</span>. Our models take into account the effect of the collapse structure considering it as a mechanical discontinuity. We also investigate the mechanical influence of the intra- and extra-<span class="hlt">caldera</span> deposits on the formation of new <span class="hlt">calderas</span>. All the numerical models are two-dimensional assuming plane strain and considering that the surrounding crust behaves as a linear homogeneous elastic material. The computational domain corresponds to a cross-section of the upper crust (50 × 25 km) and magma chambers are modelled as sill-like cavities located at a certain depth below the Earth's surface. The existing collapse <span class="hlt">caldera</span> depression is 8 km wide and 2.75 km deep, however we consider the <span class="hlt">caldera</span> infill (i.e. intra-<span class="hlt">caldera</span> material) to be 1.25 or 1.75 km thick. We assume as loading conditions an underpressure of 10 MPa imposed at the chamber walls, that is, negative excess pressure in the chamber. In some numerical runs we have considered the existence of a previous ring fault by introducing a thin and elongate vertical weak zone at the <span class="hlt">caldera</span> margins. We find that the stress field around shallow-level magma chambers favouring the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2007/1047/srp/srp072/of2007-1047srp072.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2007/1047/srp/srp072/of2007-1047srp072.pdf"><span>Elongate summit <span class="hlt">calderas</span> as Neogene paleostress indicators in Antarctica</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Paulsen, T.S.; Wilson, T.J.</p> <p>2007-01-01</p> <p>The orientations and ages of elongate summit <span class="hlt">calderas</span> on major polygenetic volcanoes were compiled to document Miocene to Pleistocene Sh (minimum horizontal stress) directions on the western and northern flanks of the West Antarctic rift system. Miocene to Pleistocene summit <span class="hlt">calderas</span> along the western Ross Sea show relatively consistent ENE long axis trends, which are at a high angle to the Transantarctic Mountain Front and parallel to the N77ºE Sh direction at Cape Roberts. The elongation directions of many Miocene to Pleistocene summit <span class="hlt">calderas</span> in Marie Byrd Land parallel the alignment of polygenetic volcanoes in which they occur, except several Pleistocene <span class="hlt">calderas</span> with consistent NNE to NE trends. The overall pattern of elongate <span class="hlt">calderas</span> in Marie Byrd Land is probably due to a combination of structurally controlled orientations and regional stress fields in which Sh is oriented NNE to NE at a moderate to high angle to the trace of the West Antarctic rift system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6098888','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6098888"><span>Land- and resource-use issues at the Valles <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Intemann, P.R.</p> <p>1981-01-01</p> <p>The Valles <span class="hlt">Caldera</span> possesses a wealth of resources from which various private parties as well as the public at large can benefit. Among the most significant of these are the geothermal energy resource and the natural resource. Wildlife, scenic, and recreational resources can be considered components of the natural resource. In addition, Native Americans in the area value the Valles <span class="hlt">Caldera</span> as part of their religion. The use of land in the <span class="hlt">caldera</span> to achieve the full benefits of one resource may adversely affect the value of other resources. Measures can be taken to minimize adverse affects and to maximize the benefits of all the varied resources within the <span class="hlt">caldera</span> as equitably as possible. An understanding of present and potential land and resource uses in the <span class="hlt">Caldera</span>, and who will benefit from these uses, can lead to the formulation of such measures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BVol...78...70C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BVol...78...70C"><span><span class="hlt">Caldera</span> collapse at near-ridge seamounts: an experimental investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coumans, Jason P.; Stix, John</p> <p>2016-10-01</p> <p>Collapse <span class="hlt">calderas</span> are sub-circular volcanic depressions caused by subsidence of the magma reservoir roof during an eruption. Scaled physical models of <span class="hlt">caldera</span> collapse using flat topography have been instrumental in investigating the spatial and temporal development of <span class="hlt">calderas</span>, in particular, two distinctive sets of concentric ring faults, one reverse and one normal. More recent analog studies have investigated the effect of non-flat topography which alters the principle stress trajectories and resulting collapse structure. This work provides the basis for investigating how naturally scaled topographic loads may affect <span class="hlt">caldera</span> collapse in relation to shallow magma reservoirs. The objective of this study is to understand how a near-ridge seamount affects <span class="hlt">caldera</span> collapse from both a central and offset position as the seamount migrates above the magma reservoir as a result of plate motion. We utilize scaled analog models of <span class="hlt">caldera</span> collapse in conjunction with three-dimensional (3D) laser scanning and digital particle image velocimetry (DPIV) to investigate <span class="hlt">caldera</span> collapse dynamics at near-ridge seamounts. Experiments using a seamount cone positioned centrally above the magma reservoir result in (1) increased subsidence along the interior outward-dipping faults and (2) a preference to more symmetric collapse patterns as indicated by the subsidence profile and structure of the <span class="hlt">caldera</span> relative to experiments with an offset cone. When the cone is offset, the collapse is asymmetric and trapdoor in nature, with the center of greatest subsidence displaced away from the region of largest topographic load. For these latter experiments, subsidence is focused where the roof is thinnest along an initial reverse fault, followed by a transition to an antithetic graben structure. The asymmetric collapse in the experiments results in a <span class="hlt">caldera</span> with a tilted profile. Offset <span class="hlt">calderas</span> at near-ridge seamounts are tilted towards the ridge axis, suggesting that they may have collapsed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6386104','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6386104"><span>Seismic imaging of the Medicine Lake <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zucca, J.J.; Evans, J.R.; Kasameyer, P.W.</p> <p>1987-04-01</p> <p>Medicine Lake Volcano, a broad shield volcano about 50 km east of Mount Shasta in northern California, produced rhylotic eruptions as recently as 400 years ago. Because of this recent activity it is of considerable interest to producers of geothermal energy. The USGS and LLNL conducted an active seismic experiment designed to explore the area beneath and around the <span class="hlt">caldera</span>. This experiment had two purposes: To produce high-quality velocity and attenuation images of the young magma body presumed to be the source for the young volcanic features, and to collect a dataset that can be used to develop and test seismic imaging methods that may be useful for understanding other geothermal systems. Eight large explosions were detonated in a 50 km radius circle around the volcano, a distance chosen to produce strong upward traveling signals through the area of interest. The data were inverted using Aki's method to produce three-dimensional velocity and attenuation images of the sub-surface. Preliminary interpretation shows low velocity and attenuation on the flanks of the volcano, and coincident high attenuation values and low velocities (-20%) from 3 to 5 km beneath the center of the <span class="hlt">caldera</span>. This zone may be a region of partial melt which fed the youngest eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26ES....3a2027W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26ES....3a2027W"><span>How piecemeal is your <span class="hlt">caldera</span>? Going beyond modelling to investigate the structural evolution of explosive <span class="hlt">caldera</span> volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Willcox, Chris; Branney, Mike; Carrasco-Núñez, Gerardo</p> <p>2008-10-01</p> <p>Despite a profusion of analogue models relatively little is known about the internal structure and temporal evolution of explosive <span class="hlt">caldera</span> volcanoes. So how can modellers test their predictions given that the internal structures of many young <span class="hlt">calderas</span> are concealed? Mapping ancient exhumed <span class="hlt">calderas</span> has proven advantageous, yet this requires a large investment of time and expertise to constrain the structural evolution in sufficient detail. We aim to investigate the interplay between the structural evolution and eruption style over time at a modern <span class="hlt">caldera</span>. We have selected Los Humeros (Mexico) because it is thought to be an example of a <span class="hlt">caldera</span> with some piecemeal development, and it also has a well-exposed pyroclastic succession and abundant borehole data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.G11A1060I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.G11A1060I"><span>Monitoring Shallow Water Vertical Seafloor Displacement: a Challenge for Seafloor Geodesy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iannaccone, G.; De Martino, P.; Chierici, F.; Pignagnoli, L.; Guardato, S.; Malservisi, R.; Beranzoli, L.; Donnarumma, G. P.</p> <p>2016-12-01</p> <p>Vertical displacement measurement in shallow seafloor poses a unique challenge for geodesy, as neither traditional land geodesy nor classical deep water marine geodesy provide valid techniques for accurate evaluations. Vertical displacement monitoring is of paramount importance in submarine volcanic areas, in marine oil extraction fields, in the study of coseismic ground movements in seismogenic areas. Sea bottom measurement of hydrostatic pressure variations could be the base to measure the vertical ground displacements. Although bottom Pressure Recorders (BPR) are affected by intrinsic limitations such as the signal drift, and shallow water are particularly affected by tides and other oceanographic effects, or rapid and sharp variations of physical properties of the sea water (e.g. temperature and salinity), BPR can be effective tools to evaluate sea bottom vertical deformation. We present unprecedented vertical displacement assessment of the marine sector of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic area (Southern Italy). These new results come from the integration of new GPS buoy, BPR and tide gauges measurements provided by the integrated monitoring system of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>. The multiparametric marine systems are operational since spring 2016 and consist of three geodetic buoys equipped with seafloor multisensor modules. The new data show on-going seafloor uplift of the submerged part of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span> and provide new contributions to the regional deformation assessment. The methodology adopted for the data processing can significantly improve our ability to understand the volcanic process extending our monitoring capabilities offshore.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70073940','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70073940"><span>Central San Juan <span class="hlt">caldera</span> cluster: Regional volcanic framework</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lipman, Peter W.</p> <p>2000-01-01</p> <p>Eruption of at least 8800 km3 of dacitic-rhyolitic magma as 9 major ash-slow sheets (individually 150-5000 km3) was accompanied by recurrent <span class="hlt">caldera</span> subsidence between 28.3 and about 26.5 Ma in the central San Juan Mountains, Colorado. Voluminous andesitic-decitic lavas and breccias were erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the <span class="hlt">calderas</span> during the period of explosive volcanism, making the central San Juan <span class="hlt">caldera</span> cluster an exceptional site for study of <span class="hlt">caldera</span>-related volcanic processes. Exposed <span class="hlt">calderas</span> vary in size from 10 to 75 km in maximum diameter, the largest <span class="hlt">calderas</span> being associated with the most voluminous eruptions. After collapse of the giant La Garita <span class="hlt">caldera</span> during eruption if the Fish Canyon Tuff at 17.6 Ma, seven additional explosive eruptions and <span class="hlt">calderas</span> formed inside the La Garita depression within about 1 m.y. Because of the nested geometry, maximum loci of recurrently overlapping collapse events are inferred to have subsided as much as 10-17 km, far deeper than the roof of the composite subvolcanic batholith defined by gravity data, which represents solidified <span class="hlt">caldera</span>-related magma bodies. Erosional dissection to depths of as much as 1.5 km, although insufficient to reach the subvolcanic batholith, has exposed diverse features of intracaldera ash-flow tuff and interleaved <span class="hlt">caldera</span>-collapse landslide deposits that accumulated to multikilometer thickness within concurrently subsiding <span class="hlt">caldera</span> structures. The <span class="hlt">calderas</span> display a variety of postcollapse resurgent uplift structures, and <span class="hlt">caldera</span>-forming events produced complex fault geometries that localized late mineralization, including the epithermal base- and precious-metal veins of the well-known Creede mining district. Most of the central San Juan <span class="hlt">calderas</span> have been deeply eroded, and their identification is dependent on detailed geologic mapping. In contrast, the primary volcanic morphology of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2185G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2185G"><span>Evolution of deep collapse <span class="hlt">caldera</span>: from structural to gravitational process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geshi, N.; Acocella, V.; Ruch, J.</p> <p>2012-04-01</p> <p>We discuss the evolution of deep-subsiding <span class="hlt">caldera</span> mainly controlled by gravitational process. Progress of <span class="hlt">caldera</span> subsidence increases its subsidence/diameter ratio (S/D ratio). We investigate the surface features of <span class="hlt">calderas</span> undergoing significant subsidence with regard to their diameter. First, we consider the evolution of the 2000 Miyakejima <span class="hlt">caldera</span>, from double-concentric ring faults at earlier collapsing stages, to a gravitational-erosion dominant stage at a mature stage. When the topographic S/D approaches 0.33, the topographic S/D (hereafter S/Dt) becomes significantly different from the structural S/D (hereafter S/Ds), owing to the gravitational erosion on the <span class="hlt">caldera</span> wall and accumulation of the debris on the floor. As collapse progresses, the peripheral block bounded by the inner reverse fault and outer normal fault extends and tilts towards the <span class="hlt">caldera</span> center; it finally collapses towards the <span class="hlt">caldera</span> floor and the double-ring faults disappeares. Subsidence of the <span class="hlt">caldera</span> floor induces the gravitational erosion of the wall. This process increases the topographic diameter and the filling of the floor decreases the topographic depth. Consequently, the S/Dt decreases, while the continuous <span class="hlt">caldera</span> subsidence increases the S/Ds. This evolution finds close similarities with the <span class="hlt">caldera</span> collapses of Krakatau (1883), Katmai (1912), Fernandina (1968), Tolbachik (1975-76), Pinatubo (1991) and Dolomieu (2007). Analogue experiments mimic the observed variation, evolving from a depression controlled by the activity of the double-ring faults to that controlled by the gravitational slumping of the wall and sedimentation at the floor. The transition occurs for S/Dt ~0.34. These results show that the control on the shape of mature <span class="hlt">calderas</span> (S/Ds>0.07) and approaching S/Dt=0.3 passes from a mainly structural to a mainly gravitational type. Both S/Dt and S/Ds are needed to describe the evolution of a collapse and the processes accompanying it. Evaluating the S/Dt and S</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6852453','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6852453"><span>Historical unrest at large <span class="hlt">calderas</span> of the world</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Newhall, C.A.; Dzurisin, D.</p> <p>1989-09-01</p> <p>This is a remarkable reference for researchers interested in volcanic hazards and silicic volcanism. Because of long repose and often obscure shapes and large size <span class="hlt">calderas</span> are a volcanic type less obvious and less well studied. Because they represent potentially highly dangerous and highly explosive volcanos which could have large-scale and even global impact when they erupt, it is very important to understand their behavior. This new volume represents an extensive effort at compiling real observations at earth's <span class="hlt">calderas</span>. The authors manage to incorporate a very impressive list of original references that go far beyond standard volcanological literature and also often extend back many centuries to include the perspective of longer historic time at some <span class="hlt">calderas</span>. If volcanologists are serious about eruption forecasting, they must be willing to dig out and absorb the lessons of historic observations as well as design instruments and make good measurements. There is an initial introductory chapter of 27 pages which attempts to lead the way to interpretation of various patterns of <span class="hlt">caldera</span> unrest, based on synthesis of the various individual cases. The meat of the volumes is in sections on the individual <span class="hlt">calderas</span>, enriched with many maps and figures documenting the <span class="hlt">caldera</span> unrest. A valuable asset of the compilation is its broad scope, which incorporates the activity of related or possibly related cones, domes, solfataras, etc., with the parent ( ) <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRB..118.1778H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRB..118.1778H"><span>Origins of oblique-slip faulting during <span class="hlt">caldera</span> subsidence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holohan, Eoghan P.; Walter, Thomas R.; SchöPfer, Martin P. J.; Walsh, John J.; Wyk de Vries, Benjamin; Troll, Valentin R.</p> <p>2013-04-01</p> <p>Although conventionally described as purely dip-slip, faults at <span class="hlt">caldera</span> volcanoes may have a strike-slip displacement component. Examples occur in the <span class="hlt">calderas</span> of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of <span class="hlt">caldera</span> subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural <span class="hlt">calderas</span>. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the <span class="hlt">caldera</span> center and (2) horizontal translation arising from off-centered or "asymmetric" subsidence. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during <span class="hlt">caldera</span> subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from <span class="hlt">calderas</span>, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V23B3104G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V23B3104G"><span>Stratigraphy of Reforma <span class="hlt">Caldera</span>, Baja California Sur, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García Sánchez, L.; Macias, J. L.; Osorio, L. S.; Pola, A.; Avellán, D. R.; Arce, J. L.; Saucedo, R.; Sánchez, J. M.; García-Tenorio, F.; Cisneros, G.; Reyes-Agustín, G.; Cardona, S.; Jimenez, A.</p> <p>2015-12-01</p> <p>The Reforma <span class="hlt">caldera</span> is located at ~35 km to the northwest of Santa Rosalía in the central part of the Baja California peninsula. It has 10 km in diameter and a maximum height of 1200 masl in the center and between 100 and 500 masl in its slopes. Reforma is within a tectonic zone affected by two fault systems: A NW-SE normal fault system linked to the opening of the Gulf of California, and a NNW-SSE and NW-SE strike-slip fault system associated with an active Riedel system. Reforma was built upon Cretaceous granites that outcrop at the <span class="hlt">caldera</span> center, Miocene to Pliocene volcano-sedimentary rocks of the Comondú group, and Miocene marine sediments of the Santa Rosalía basin. On top of these rocks outcrop at least four submarine to subaerial ignimbrites interbedded with marine fossiliferous beds and the lower Pleistocene deposits associated to the Reforma <span class="hlt">caldera</span>. These deposits are formed by a ignimbrite that shifts to different lithofacies that change gradually their welding, here dubbed basal, transitional, intermediate, and upper (all of then enriched in black fiammes), followed by a pumice-rich, white fiammes, and vitrophyre lithofacies, which are distributed around the 9 km wide <span class="hlt">caldera</span> and have been associated to the <span class="hlt">caldera</span> formation episode. Deposits related to post-<span class="hlt">caldera</span> volcanism are andesite-basaltic lava flows erupted along the <span class="hlt">caldera</span> rim through localized feeding dikes and andesitic and rhyolitic domes, and scoria cinder cones exposed inside and outside the <span class="hlt">caldera</span>. On top of these deposits rest the middle Pleistocene Aguajito <span class="hlt">caldera</span> deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016303','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016303"><span>Recent crustal subsidence at Yellowstone <span class="hlt">Caldera</span>, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dzurisin, D.; Savage, J.C.; Fournier, R.O.</p> <p>1990-01-01</p> <p>Following a period of net uplift at an average rate of 15??1 mm/year from 1923 to 1984, the east-central floor of Yellowstone <span class="hlt">Caldera</span> stopped rising during 1984-1985 and then subsided 25??7 mm during 1985-1986 and an additional 35??7 mm during 1986-1987. The average horizontal strain rates in the northeast part of the <span class="hlt">caldera</span> for the period from 1984 to 1987 were: {Mathematical expression}1 = 0.10 ?? 0.09 ??strain/year oriented N33?? E??9?? and {Mathematical expression}2 = 0.20 ?? 0.09 ??strain/year oriented N57?? W??9?? (extension reckoned positive). A best-fit elastic model of the 1985-1987 vertical and horizontal displacements in the eastern part of the <span class="hlt">caldera</span> suggests deflation of a horizontal tabular body located 10??5 km beneath Le Hardys Rapids, i.e., within a deep hydrothermal system or within an underlying body of partly molten rhyolite. Two end-member models each explain most aspects of historical unrest at Yellowstone, including the recent reversal from uplift to subsidence. Both involve crystallization of an amount of rhyolitic magma that is compatible with the thermal energy requirements of Yellowstone's vigorous hydrothermal system. In the first model, injection of basalt near the base of the rhyolitic system is the primary cause of uplift. Higher in the magmatic system, rhyolite crystallizes and releases all of its magmatic volatiles into the shallow hydrothermal system. Uplift stops and subsidence starts whenever the supply rate of basalt is less than the subsidence rate produced by crystallization of rhyolite and associated fluid loss. In the second model, uplift is caused primarily by pressurization of the deep hydrothermal system by magmatic gas and brine that are released during crystallization of rhyolite and them trapped at lithostatic pressure beneath an impermeable self-sealed zone. Subsidence occurs during episodic hydrofracturing and injection of pore fluid from the deep lithostatic-pressure zone into a shallow hydrostatic-pressure zone</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1246122','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1246122"><span>AmeriFlux US-Vcp Valles <span class="hlt">Caldera</span> Ponderosa Pine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Litvak, Marcy</p> <p>2016-01-01</p> <p>This is the AmeriFlux version of the carbon flux data for the site US-Vcp Valles <span class="hlt">Caldera</span> Ponderosa Pine. Site Description - The Valles <span class="hlt">Caldera</span> Ponderosa Pine site is located in the 1200km2 Jemez River basin of the Jemez Mountains in north-central New Mexico at the southern margin of the Rocky Mountain ecoregion. The Ponderosa Pine forest is the warmest and lowest (below 2700m) zone of the forests in the Valles <span class="hlt">Caldera</span> National Preserve. Its vegetation is composed of a Ponderosa Pine (Pinus Ponderosa) overstory and a Gambel Oak (Quercus gambelii) understory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790030631&hterms=qualitative+observation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dqualitative%2Bobservation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790030631&hterms=qualitative+observation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dqualitative%2Bobservation"><span>Imaging radar observations of Askja <span class="hlt">Caldera</span>, Iceland</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Malin, M. C.; Evans, D.; Elachi, C.</p> <p>1978-01-01</p> <p>A 'blind' test involving interpretation of computer-enhanced like- and cross-polarized radar images is used to evaluate the surface roughness of Askja <span class="hlt">Caldera</span>, a large volcanic complex in central Iceland. The 'blind' test differs from earlier analyses of radar observations in that computer-processes images and both qualitative and quantitative analyses are used. Attention is given to photogeologic examination and subsequent survey-type field observations, along with aerial photography during the field trip. The results indicate that the 'blind' test of radar interpretation of the Askja volcanic area can be considered suitable within the framework of limitations of radar data considered explicitly from the onset. The limitations of the radar techniques can be eliminated by using oblique-viewing conditions to remove geometric distortions and slope effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790030631&hterms=Iceland&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DIceland','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790030631&hterms=Iceland&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DIceland"><span>Imaging radar observations of Askja <span class="hlt">Caldera</span>, Iceland</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Malin, M. C.; Evans, D.; Elachi, C.</p> <p>1978-01-01</p> <p>A 'blind' test involving interpretation of computer-enhanced like- and cross-polarized radar images is used to evaluate the surface roughness of Askja <span class="hlt">Caldera</span>, a large volcanic complex in central Iceland. The 'blind' test differs from earlier analyses of radar observations in that computer-processes images and both qualitative and quantitative analyses are used. Attention is given to photogeologic examination and subsequent survey-type field observations, along with aerial photography during the field trip. The results indicate that the 'blind' test of radar interpretation of the Askja volcanic area can be considered suitable within the framework of limitations of radar data considered explicitly from the onset. The limitations of the radar techniques can be eliminated by using oblique-viewing conditions to remove geometric distortions and slope effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4961867','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4961867"><span>Magma storage in a strike-slip <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Saxby, J.; Gottsmann, J.; Cashman, K.; Gutiérrez, E.</p> <p>2016-01-01</p> <p>Silicic <span class="hlt">calderas</span> form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in <span class="hlt">caldera</span>-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango <span class="hlt">caldera</span>, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the <span class="hlt">caldera</span> is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions. PMID:27447932</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...712295S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...712295S"><span>Magma storage in a strike-slip <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saxby, J.; Gottsmann, J.; Cashman, K.; Gutiérrez, E.</p> <p>2016-07-01</p> <p>Silicic <span class="hlt">calderas</span> form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in <span class="hlt">caldera</span>-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango <span class="hlt">caldera</span>, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the <span class="hlt">caldera</span> is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27447932','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27447932"><span>Magma storage in a strike-slip <span class="hlt">caldera</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saxby, J; Gottsmann, J; Cashman, K; Gutiérrez, E</p> <p>2016-07-22</p> <p>Silicic <span class="hlt">calderas</span> form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in <span class="hlt">caldera</span>-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango <span class="hlt">caldera</span>, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the <span class="hlt">caldera</span> is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/104424','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/104424"><span>Intracaldera volcanism and sedimentation-Creede <span class="hlt">caldera</span>, Colorado</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heiken, G.; Krier, D.; Snow, M.G.; McCormick, T.</p> <p>1994-12-31</p> <p>Within the Creede <span class="hlt">caldera</span>, Colorado, many of the answers to its postcaldera volcanic and sedimentary history lie within the sequence of tuffaceous clastic sedimentary rocks and tuffs known as the Creede Formation. The Creede Formation and its interbedded ash deposits were sampled by research coreholes Creede 1 and 2, drilled during the fall of 1991. In an earlier study of the Creede Formation, based on surface outcrops and shallow mining company coreholes, Heiken and Krier (1987) concluded that the process of <span class="hlt">caldera</span> structural resurgence was rapid and that a <span class="hlt">caldera</span> lake had developed in an annulus (``moat``) located between the resurgent dome and <span class="hlt">caldera</span> wall. So far we have a picture of intracaldera activity consisting of intermittent hydrovoleanic eruptions within a <span class="hlt">caldera</span> lake for the lower third of the Creede Formation, and both magmatic and hydrovolcanic ash eruptions throughout the top two-thirds. Most of the ash deposits interbedded with the moat sedimentary rocks are extremely fine-grained. Ash fallout into the moat lake and unconsolidated ash eroded from <span class="hlt">caldera</span> walls and the slopes of the resurgent dome were deposited over stream delta distributaries within relatively shallow water in the northwestern moat, and in deeper waters of the northern moat, where the <span class="hlt">caldera</span> was intersected by a graben. Interbedded with ash beds and tuffaceous siltstones are coarse-grained turbidites from adjacent steep slopes and travertine from fissure ridges adjacent to the moat. Sedimentation rates and provenance for clastic sediments are linked to the frequent volcanic activity in and near the <span class="hlt">caldera</span>; nearly all of the Creede Formation sedimentary rocks are tuffaceous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780025702','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780025702"><span>Radar observations of a volcanic terrain: Askja <span class="hlt">Caldera</span>, Iceland</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evans, D. L.</p> <p>1978-01-01</p> <p>Surface roughness spectra of nine radar backscatter units in the Askja <span class="hlt">caldera</span> region of Iceland were predicted from computer-enhanced like- and cross-polarized radar images. A field survey of the <span class="hlt">caldera</span> was then undertaken to check the accuracy of the preliminary analysis. There was good agreement between predicted surface roughness of backscatter units and surface roughness observed in the field. In some cases, variations in surface roughness could be correlated with previously mapped geologic units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6051142','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6051142"><span>Gravity and fault structures, Long Valley <span class="hlt">caldera</span>, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carle, S.F.; Goldstein, N.E.</p> <p>1987-07-01</p> <p>The main and catastrophic phase of eruption in Long Valley occurred 0.73 m.y. ago with the eruption of over 600 km/sup 3/ of rhyolitic magma. Subsequent collapse of the roof rocks produced a <span class="hlt">caldera</span> which is now elliptical in shape, 32 km east-west by 17 km north-south. The <span class="hlt">caldera</span>, like other large Quarternary silicic ash-flow volcanoes that have been studied by various workers, has a nearly coincident Bouguer gravity low. Earlier interpretations of the gravity anomaly have attributed the entire anomaly to lower density rocks filling the collapsed structure. However, on the basis of many additional gravity stations and supporting subsurface data from several new holes, a much more complex and accurate picture has emerged of <span class="hlt">caldera</span> structure. From a three-dimensional inversion of the residual Bouguer gravity data we can resolve discontinuities that seem to correlate with extensions of pre-<span class="hlt">caldera</span> faults into the <span class="hlt">caldera</span> and faults associated with the ring fracture. Some of these faults are believed related to the present-day hydrothermal upflow zone and the zone of youngest volcanic activity within the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS058-73-024&hterms=cities+Italian&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcities%2BItalian','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS058-73-024&hterms=cities+Italian&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcities%2BItalian"><span>Mt. Vesuvius and Naples, Italy as seen from STS-58</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1993-01-01</p> <p>The ancient eruption of Vesuvius (the volcanoe near the center of the frame) destroyed the town of Pompeii located on the southeast flank. But the larger town of Naples, between Vesuvius (to the south) and the large, circular, lake-filled <span class="hlt">caldera</span> of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (to the west) is also close to volcanic hazards. In this view, Naples is the gray urban area with substantial coastal development just northwest of Vesuvius. Other landmarks marking the Italian coast include the small island of Capri, just off the west-pointing peninsula, and the city of Salerno on the coast just south of the same peninsula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=STS058-73-024&hterms=Pompeii&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPompeii','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=STS058-73-024&hterms=Pompeii&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPompeii"><span>Mt. Vesuvius and Naples, Italy as seen from STS-58</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1993-01-01</p> <p>The ancient eruption of Vesuvius (the volcanoe near the center of the frame) destroyed the town of Pompeii located on the southeast flank. But the larger town of Naples, between Vesuvius (to the south) and the large, circular, lake-filled <span class="hlt">caldera</span> of <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> (to the west) is also close to volcanic hazards. In this view, Naples is the gray urban area with substantial coastal development just northwest of Vesuvius. Other landmarks marking the Italian coast include the small island of Capri, just off the west-pointing peninsula, and the city of Salerno on the coast just south of the same peninsula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V13C2376W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V13C2376W"><span>Can the structure of an explosive <span class="hlt">caldera</span> affect eruptive behaviour?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Willcox, C. P.; Branney, M.; Carrasco-Nuñez, G.; Barford, D.</p> <p>2010-12-01</p> <p>Explosive <span class="hlt">caldera</span> volcanoes cause catastrophic events at the Earth’s surface, yet we know little about how their internal structures evolve with time, and whether this can affect both differentiation and eruptive behaviour. Distinguishing how structural evolution impacts upon eruption behaviour and periodicity is challenging because the resolution of eruption frequencies can be difficult at ancient exhumed <span class="hlt">calderas</span>, whereas at young volcanoes, most of the <span class="hlt">caldera</span> floor faults and associated conduits are hidden. Some exhumed <span class="hlt">calderas</span> reveal <span class="hlt">caldera</span> floor faults and conduits; some of these apparently underwent a single collapse event that was piecemeal, i.e. fragmentation into several, variously subsided fault-blocks (e.g. Scafell <span class="hlt">caldera</span>, UK). In contrast, the present study tests whether some <span class="hlt">caldera</span> volcanoes may become more intensely fractured with time as a result of successive distinct <span class="hlt">caldera</span>-collapse eruptions (“multi-cyclic calderas”). It has been proposed that this scenario could lead to an increase in eruption frequency, with smaller eruptions over time. Magma leakage through the increasingly fractured volcano might also lead to less evolved compositions with time due to shorter residence times. We have returned to the volcano where this hypothesis was formulated, the ~ 20 km diameter, hydrothermally active Los Humeros <span class="hlt">caldera</span> in eastern central México. We aim to see how well the structural evolution of this modern <span class="hlt">caldera</span> can be reconstructed, and whether changes in structure affected the styles and periodicity of large explosive eruptions. How a <span class="hlt">caldera</span> evolves structurally could have important implications for predicting future catastrophic eruptions. Detailed structural mapping (e.g. of fault scarps, vent positions, and tilted strata), documentation of draping and cross-cutting field relations, together with logging, optical and SEM petrography, XRF major and trace element geochemistry and new 40Ar-39Ar and radiocarbon dating of the pyroclastic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.6053N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.6053N"><span>Submarine Volcanic Morphology of Santorini <span class="hlt">Caldera</span>, Greece</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nomikou, P.; Croff Bell, K.; Carey, S.; Bejelou, K.; Parks, M.; Antoniou, V.</p> <p>2012-04-01</p> <p>Santorini volcanic group form the central part of the modern Aegean volcanic arc, developed within the Hellenic arc and trench system, because of the ongoing subduction of the African plate beneath the European margin throughout Cenozoic. It comprises three distinct volcanic structures occurring along a NE-SW direction: Christianna form the southwestern part of the group, Santorini occupies the middle part and Koloumbo volcanic rift zone extends towards the northeastern part. The geology of the Santorini volcano has been described by a large number of researchers with petrological as well as geochronological data. The offshore area of the Santorini volcanic field has only recently been investigated with emphasis mainly inside the Santorini <span class="hlt">caldera</span> and the submarine volcano of Kolumbo. In September 2011, cruise NA-014 on the E/V Nautilus carried out new surveys on the submarine volcanism of the study area, investigating the seafloor morphology with high-definition video imaging. Submarine hydrothermal vents were found on the seafloor of the northern basin of the Santorini <span class="hlt">caldera</span> with no evidence of high temperature fluid discharges or massive sulphide formations, but only low temperature seeps characterized by meter-high mounds of bacteria-rich sediment. This vent field is located in line with the normal fault system of the Kolumbo rift, and also near the margin of a shallow intrusion that occurs within the sediments of the North Basin. Push cores have been collected and they will provide insights for their geochemical characteristics and their relationship to the active vents of the Kolumbo underwater volcano. Similar vent mounds occur in the South Basin, at shallow depths around the islets of Nea and Palaia Kameni. ROV exploration at the northern slopes of Nea Kameni revealed a fascinating underwater landscape of lava flows, lava spines and fractured lava blocks that have been formed as a result of 1707-1711 and 1925-1928 AD eruptions. A hummocky topography at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00485&hterms=sag&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsag','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00485&hterms=sag&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsag"><span>Venus - A Large Elongated <span class="hlt">Caldera</span> 'Sacajawea Patera</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>This Magellan image reveals Sacajawea Patera, a large, elongate <span class="hlt">caldera</span> located in Western Ishtar Terra on the smooth plateau of Lakshmi Planum. The image is centered at 64.5 degrees North latitude and 337 degrees East longitude. It is approximately 420 kilometers (252 miles) wide at the base. Sacajawea is a depression approximately 1-2 kilometers (0.6-1.2 miles) deep and 120 x 215 kilometers (74 x 133 miles) in diameter; it is elongate in a southwest-northeast direction. The depression is bounded by a zone of circumferential curvilinear structures interpreted to be graben and fault scarps. These structures are spaced 0.5-4 kilometers (0.3-2.5 miles) apart, are 0.6-4.0 kilometers (0.4-2.5 miles) in width and up to 100 kilometers (62 miles) in length. Extending up to approximately 140 kilometers (87 miles) in length from the southeast of the patera is a system of linear structures thought to represent a flanking rift zone along which the lateral injection and eruption of magma may have occurred. A shield edifice 12 kilometers (7 miles) in diameter with a prominent central pit lies along the trend of one of these features. The impact crater Zlata, approximately 6 kilometers (4 miles) in diameter is located within the zone of graben to the northwest of the patera. Few flow features are observed in association with Sacajawea, possibly due to age and state of degradation of the flows. Mottled bright deposits 4-20 kilometers (2.5-12 miles) in width are located near the periphery and in the center of the patera floor within local topographic lows. Diffuse patches of dark material approximately 40 kilometers (25 miles) in width are observed southwest of the patera, superposed on portions of the surrounding graben. The formation of Sacajawea is thought to be related to the drainage and collapse of a large magma chamber. Gravitational relaxation may have caused the resultant <span class="hlt">caldera</span> to sag, producing the numerous faults and graben that circumscribe the patera. Regions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26ES....3a2008N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26ES....3a2008N"><span>Geology and structure of the Malpaso <span class="hlt">caldera</span> and El Ocote ignimbrite, Aguascalientes, Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nieto-Obregón, Jorge; Aguirre-Díaz, Gerardo</p> <p>2008-10-01</p> <p>A new <span class="hlt">caldera</span>, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso <span class="hlt">caldera</span> is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the <span class="hlt">caldera</span> collapse. Due to these characteristics it as a graben <span class="hlt">caldera</span>. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this <span class="hlt">caldera</span>, as well as a description of the main <span class="hlt">caldera</span> product, the high-grade El Ocote ignimbrite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033639','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033639"><span>Kaguyak dome field and its Holocene <span class="hlt">caldera</span>, Alaska Peninsula</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fierstein, J.; Hildreth, W.</p> <p>2008-01-01</p> <p>Kaguyak <span class="hlt">Caldera</span> lies in a remote corner of Katmai National Park, 375??km SW of Anchorage, Alaska. The 2.5-by-3-km <span class="hlt">caldera</span> collapsed ~ 5.8 ?? 0.2??ka (14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80??km southwest. Postcaldera events include filling the 150-m-deep <span class="hlt">caldera</span> lake, emplacement of two intracaldera domes (61.5-64.5% SiO2), and phreatic ejection of lakefloor sediments onto the <span class="hlt">caldera</span> rim. CO2 and H2S bubble up through the lake, weakly but widely. Geochemical analyses (n = 148), including pre-and post-<span class="hlt">caldera</span> lavas (53-74% SiO2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60??ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200??years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep <span class="hlt">caldera</span> wall, which beheads gullies incised into the breccia deposit prior to <span class="hlt">caldera</span> formation. They were probably shed by a large lava dome extruding where the lake is today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..177..340F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..177..340F"><span>Kaguyak dome field and its Holocene <span class="hlt">caldera</span>, Alaska Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fierstein, Judy; Hildreth, Wes</p> <p>2008-10-01</p> <p>Kaguyak <span class="hlt">Caldera</span> lies in a remote corner of Katmai National Park, 375 km SW of Anchorage, Alaska. The 2.5-by-3-km <span class="hlt">caldera</span> collapsed ~ 5.8 ± 0.2 ka ( 14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO 2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80 km southwest. Postcaldera events include filling the 150-m-deep <span class="hlt">caldera</span> lake, emplacement of two intracaldera domes (61.5-64.5% SiO 2), and phreatic ejection of lakefloor sediments onto the <span class="hlt">caldera</span> rim. CO 2 and H 2S bubble up through the lake, weakly but widely. Geochemical analyses ( n = 148), including pre-and post-<span class="hlt">caldera</span> lavas (53-74% SiO 2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60 ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200 years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO 2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep <span class="hlt">caldera</span> wall, which beheads gullies incised into the breccia deposit prior to <span class="hlt">caldera</span> formation. They were probably shed by a large lava dome extruding where the lake is today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/60620','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/60620"><span>Post-Silent Canyon <span class="hlt">caldera</span> structural setting for Pahute Mesa</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Warren, R.G.; Byers, F.M. Jr.; Orkild, P.P.</p> <p>1985-12-31</p> <p>At Pahute Mesa, Nevada Test Site, the Silent Canyon <span class="hlt">caldera</span> of about 14 Ma age is almost completely concealed beneath ash-flow tuffs of the 11.5 Ma old Rainier Mesa Member of the Timber Mountain Tuff. Structures unequivocally related to the <span class="hlt">caldera</span> are not observed in the Rainier Mesa Member. Structure contours on top of Rainier Mesa Member at Pahute Mesa define a series of elongate, fault-bounded blocks. Between the East Boxcar and Almendro Faults these blocks tilt eastward away from westward-dipping normal faults and elsewhere they also have a strong northward component of dip, away from Timber Mountain <span class="hlt">caldera</span>. Episodic movement along these faults controlled thicknesses of members of Paintbrush Tuff (13.3 - 12.7 Ma) and tuffs and lavas of Area 20 (14 - 13.3 Ma), which have steeper eastward and northward components of dip than the overlying Rainier Mesa Member and also thicken eastward within each structural block. Fault blocks north of Timber Mountain <span class="hlt">caldera</span> on Pahute Mesa are very similar to blocks described at Yucca mountain south of the <span class="hlt">caldera</span>, and probably were generated by regional Basin and Range extension and four episodes of <span class="hlt">caldera</span>-forming volcanism at Timber Mountain. Faults bounding these blocks on Pahute Mesa formed during early episodes of <span class="hlt">caldera</span>-forming volcanism at Timber Mountain and reactivated during later episodes, so that fault displacements and bedding plane attitudes increase with age. Because these faults have episodic activity, even a relatively small post-Rainier Mesa displacement may define the location of important displacement within underlying units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V51B4739M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V51B4739M"><span>Towards a General Model for Volcanic <span class="hlt">Caldera</span> Dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Macedonio, G.; Giudicepietro, F.; D'auria, L.; Martini, M.</p> <p>2014-12-01</p> <p>Volcanic <span class="hlt">calderas</span> often show a behavior different from that of other volcanoes. In <span class="hlt">caldera</span> complexes, it is not unusual to record long-term unrests, with remarkable ground deformation, seismicity, and geochemical changes, that do not culminate in an eruption. On the contrary, in certain cases, an unrest accompanied by minor geophysical changes can be followed in few months by an eruption, as in the case of Rabaul <span class="hlt">Caldera</span> in 1994. Those behaviors are not simple to interpret. The dramatic advances in volcano monitoring over the last years has allowed us to record the dynamic phenomena of several <span class="hlt">calderas</span> with great detail. This, highlighted characteristics that are typical of a single <span class="hlt">caldera</span>, but also some features common to several <span class="hlt">calderas</span>. The main common features are remarkable ground deformation with intense uplift episodes, that are often followed by subsidence. The ground deformations are generally characterized by strong horizontal components. The seismicity is almost always in swarms and has a spatial distribution that often shows seismic gaps. Moreover, <span class="hlt">calderas</span> are the largest geothermal systems in the world. We think that a process of sill intrusion can explain the common features highlighted by many observations carried out on different <span class="hlt">calderas</span>. We developed a dynamic model of sill intrusion in a shallow volcanic environment. In our model, the sill, fed by a deeper magma reservoir, intrudes below a horizontal elastic plate, representing the overlying rocks, and expands with axisymmetric geometry. The model is based on the numerical solution of the equation for the elastic plate, coupled with a Navier-Stokes equation for simulating the dynamics of the sill intrusion. We performed a number of simulations, with the objective of showing the main features of the model. In the experiments, when the feeding process stops, the vertical movement reverses its trend and the area of maximum uplift undergoes subsidence. Under certain conditions the subsidence can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982JHyd...56..119G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982JHyd...56..119G"><span>Valles <span class="hlt">Caldera</span> geothermal systems, New Mexico, U.S.A.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goff, Fraser; Grigsby, Charles O.</p> <p>1982-03-01</p> <p>Valles <span class="hlt">Caldera</span> is part of a Quaternary silicic volcano in northern New Mexico that possesses enormous geothermal potential. The <span class="hlt">caldera</span> has formed at the intersection of the volcanically active Jemez lineament and the tectonically active Rio Grande rift. Volcanic rocks of the Jemez Mountains overlie Paleozoic—Mesozoic sediments, and Precambrian granitic basement. Although the regional heat flow along the Rio Grande rift is ~2.7 HFU , convective heat flow within the <span class="hlt">caldera</span> exceeds 10 HFU. A moderately saline hotwater geothermal system ( T > 260° C, Cl ⋍ 3000 mg/ l) has been tapped in fractured <span class="hlt">caldera</span>-fill ignimbrites at depths of 1800 m. Surface geothermal phenomena include central fumaroles and acid-sulfate springs surrounded by dilute thermal meteoric hot springs. Derivative hot springs from the deep geothermal reservoir issue along the Jemez fault zone, 10 km southwest of the <span class="hlt">caldera</span>. Present geothermal projects are: (1) proposed construction of an initial 50-MW el power plant utilizing the known geothermal reservoir; (2) research and development of the prototype hot dry rock (HDR) geothermal system that circulates surface water through deep Precambrian basement (˜5MW th); (3) exploration for deep hot fluids in adjacent basin-fill sediments of the Rio Grande rift; and (4) shallow exploration drilling for hot fluids along the Jemez fault zone. 1 HFU (heat flow unit) = 1 μcal. s -2 cm -2 = 41.67 mW m -2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6069691','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6069691"><span>Science guide for the Long Valley <span class="hlt">Caldera</span> deep hole</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rundle, J.B.; Eichelberger, J.C.</p> <p>1989-05-01</p> <p>The Magma Energy Program of the US Department of Energy, Geothermal Technology Division, is planning to begin drilling a deep (6 km) exploration well in Long Valley <span class="hlt">Caldera</span>, California, in September 1988. The location of the well is in the central part of the <span class="hlt">caldera</span>, coincident with a large number of shallow (5-7 km) geophysical anomalies identified through many independent investigations. Results from the hole will permit the following: direct investigation of the geophysical anomalies interpreted to be magma; investigation of the patterns and conditions of deep fluid circulation and heat transport below the <span class="hlt">caldera</span> floor; determination of the amount of collapse and subsequent resurgence of the central portion of Long Valley <span class="hlt">caldera</span>; and determination of the intrusion history of the central plutonic complex beneath the <span class="hlt">caldera</span>, and establishment of the relationship of intrusive to eruptive events. The hole will thus provide a stringent test of the hypothesis that magma is still present within the central plutonic complex. If the interpretation of geophysical anomalies is confirmed, the hole will provide the first observations of the environment near a large silicic magma chamber. 80 refs., 7 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/50495','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/50495"><span>Is the Valles <span class="hlt">caldera</span> entering a new cycle of activity?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wolff, J.A.; Gardner, J.N.</p> <p>1995-05-01</p> <p>The Valles <span class="hlt">caldera</span> formed during two major rhyolitic ignimbrite eruptive episodes (the Bandelier Tuff) at 1.61 and 1.22 Ma, after some 12 m.y. of activity in the Jemez Mountains volcanic field, New Mexico. Several subsequent eruptions between 1.22 and 0.52 Ma produced dominantly high-silica rhyolite lava domes and tephras within the <span class="hlt">caldera</span>. These were followed by a dormancy of 0.46 m.y. prior to the most recent intracaldera activity, the longest hiatus since the inception of the Bandelier magma system at approximately 1.8 Ma. The youngest volcanic activity at approximately 60 ka produced the SW moat rhyolites, a series of lavas and tuffs that display abundant petrologic evidence of being newly generated melts. Petrographic textures conform closely to published predictions for silicic magmas generated by intrusion of basaltic magma into continental crust. The Valles <span class="hlt">caldera</span> may currently be the site of renewed silicic magma generation, induced by intrusion of mafic magma at depth. Recent seismic investigations revealed the presence of a large low-velocity anomaly in the lower crust beneath the <span class="hlt">caldera</span>. The generally aseismic character of the <span class="hlt">caldera</span>, despite abundant regional seismicity, may be attributed to a heated crustal column, the local effect of 13 m.y. of magmatism and emplacement of mid-crustal plutons. 24 refs., 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/894723','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/894723"><span>Continental Scientific Drilling Program: Valles <span class="hlt">Caldera</span>, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1993-01-01</p> <p>The U.S. Continental Scientific Drilling Program attempts to develop a better understanding of the geologic and hydrologic mechanisms within the continental crust, under the auspices of an interagency group comprising the US Department of Energy, the National Science Foundation, and the U.S. Geological Survey. Ten years of research and drilling in the Valles <span class="hlt">caldera</span> of northern New Mexico has provided a new understanding of volcanism and geothermal systems within a large <span class="hlt">caldera</span>. Situated at the intersection of the Rio Grande rift and the Jemez volcanic lineament, the Valles <span class="hlt">caldera</span> and Toledo <span class="hlt">calderas</span> were formed during two massive eruptions 1.1 and 1.5 M a that vented approximately 300 to 400 km{sup 3} of high-silica rhyolitic tephra. The research at the Valles/Toledo <span class="hlt">caldera</span> has provided more than 3000 m of corehole samples, which are stored in a repository in Grand Junction, Colorado, and are accessible to the public. This research has also helped support theories of mineral deposition within hydrothermal systems-hot water circulating through breccias, leaching elements from the rocks, and later depositing veins of economically valuable materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029443','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029443"><span>Unrest in Long Valley <span class="hlt">Caldera</span>, California, 1978-2004</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hill, David P.; ,</p> <p>2006-01-01</p> <p>Long Valley <span class="hlt">Caldera</span> and the Mono-Inyo Domes volcanic field in eastern California lie in a left-stepping offset along the eastern escarpment of the Sierra Nevada, at the northern end of the Owens Valley and the western margin of the Basin and Range Province. Over the last 4 Ma, this volcanic field has produced multiple volcanic eruptions, including the <span class="hlt">caldera</span>-forming eruption at 760 000 a BP and the recent Mono-Inyo Domes eruptions 500–660 a BP and 250 a BP. Beginning in the late 1970s, the <span class="hlt">caldera</span> entered a sustained period of unrest that persisted through the end of the century without culminating in an eruption. The unrest has included recurring earthquake swarms; tumescence of the resurgent dome by nearly 80 cm; the onset of diffuse magmatic carbon dioxide emissions around the flanks of Mammoth Mountain on the southwest margin of the <span class="hlt">caldera</span>; and other indicators of magma transport at mid- to upper-crustal depths. Although we have made substantial progress in understanding the processes driving this unrest, many key questions remain, including the distribution, size, and relation between magma bodies within the mid-to-upper crust beneath the <span class="hlt">caldera</span>, Mammoth Mountain, and the Inyo Mono volcanic chain, and how these magma bodies are connected to the roots of the magmatic system in the lower crust or upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/243986','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/243986"><span>A geophysical-geological transect of the Silent Canyon <span class="hlt">caldera</span> complex, Pahute Mesa, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferguson, J.F.; Cogbill, A.H.; Warren, R.G.</p> <p>1994-03-10</p> <p>Revision of lithological logs for boreholes penetrating the volcanic center at Pahute Mesa, Neveda, has led to a thorough review of the volcanic stratigraphy and geologic structure. The authors have combined this review with a compilation of old and newly acquired gravity and seismic travel time data, producing a unified interpretation along a northwest to southeast profile. The analysis supports a new interpretation of the Silent Canyon <span class="hlt">caldera</span> complex. The <span class="hlt">caldera</span> is found to be more asymmetric than previously suggested, with the southeastern boundary formed by linear, high-angle normal faults and a more gently sloping northwestern boundary. The total thickness of volcanic units within the <span class="hlt">caldera</span> complex does not appear to exceed 5 km. The shallow structure at Pahute Mesa could have a profound effect on the seismic response for regional and teleseismic signals from this nuclear test site. The Silent Canyon <span class="hlt">caldera</span> complex is actually a set of nested <span class="hlt">calderas</span> first filled by thick (>1 km) postcaldera lavas and subsequently buried by outflow sheets of the Timber Mountain <span class="hlt">caldera</span> to the south. Thick, postcaldera lavas filled a half-graben structure formed west of the West Greeley fault, dropping the tops of the youngest <span class="hlt">caldera</span>-forming units to depths in excess of 2 km. Therefore the western boundary of the <span class="hlt">caldera</span> complex is poorly defined. East of the West Greeley fault, two overlapping <span class="hlt">calderas</span> are defined, and stratigraphic data suggest the presence of even older <span class="hlt">calderas</span>. The youngest <span class="hlt">caldera</span>, the calc-alkaline Area 20 <span class="hlt">caldera</span>, is well defined from drill hole data. The Area 20 <span class="hlt">caldera</span> overlaps the 13.6 Ma peralkaline Grouse Canyon <span class="hlt">caldera</span>, which is less well defined, but apparently collapsed in trap-door style along the Almendro fault. For both these <span class="hlt">calderas</span>, collapse continued after the main <span class="hlt">caldera</span>-forming eruption, concurrent with the accumulation of thick (>1 km) lavas within the peripheral collapse zones. 67 refs., 13 figs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6997858','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6997858"><span>Ash-flow eruptive megabreccias of the Manhattan and Mount Jefferson <span class="hlt">calderas</span>, Nye County, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shawe, D.R.; Snyder, D.B.</p> <p>1988-01-01</p> <p>A detailed field study of ash-flow megabreccias associated with the Manhattan and Mount Jefferson <span class="hlt">calderas</span> shows that megaclasts were brecciated in sub-<span class="hlt">caldera</span> level before incorporation in ash flows. This evidence in addition to the presence of some clast lithologies that are nowhere recognized in <span class="hlt">caldera</span> walls and the occurrence of some megabreccia units as outflow suggest an origin by eruption rather than by collapse of <span class="hlt">caldera</span> walls. Geophysical investigations and a mathematical analysis are presented in the paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5165076','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5165076"><span>Core log: Valles <span class="hlt">caldera</span> No. 2A, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Starguist, V.L.</p> <p>1988-01-01</p> <p>Scientific core hole VC-2A was drilled into the western ring-fracture zone at Sulphur Springs in the Valles <span class="hlt">caldera</span>, New Mexico. VC-2A, the second scientific core hole in the <span class="hlt">caldera</span>, was cored through a faulted and brecciated sequence of intracauldron tuffs and volcaniclastic rocks to a depth of 528 m. As of November 1, 1986, the unequilibrated bottom-hole temperature was 212/degree/C. The rocks penetrated are intensely altered and host sub-ore grade stockwork molybdenite mineralization between 25 and 125 m. This report contains a detailed core log to aid researchers in their studies of the Valles <span class="hlt">caldera</span> magma hydrothermal system. 3 refs., 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3628075','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3628075"><span>Carbonatite ring-complexes explained by <span class="hlt">caldera</span>-style volcanism</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R.; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria</p> <p>2013-01-01</p> <p>Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by <span class="hlt">caldera</span>-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. <span class="hlt">Caldera</span> subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic <span class="hlt">calderas</span>. PMID:23591904</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015215','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015215"><span>The hydrothermal system of the Calabozos <span class="hlt">caldera</span>, central Chilean Andes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grunder, A.L.; Thompson, J.M.; Hildreth, W.</p> <p>1987-01-01</p> <p>Active thermal springs associated with the late Pleistocene Calabozos <span class="hlt">caldera</span> complex occur in two groups: the Colorado group which issues along structures related to <span class="hlt">caldera</span> collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ???400 ppm Cl at ???250??C by dilution with ???50% of cold meteoric water. The thermal springs in the most deeply eroded part of the <span class="hlt">caldera</span> were derived from the same parent water by boiling. The hydrothermal system has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos hydrothermal system would be an attractive geothermal prospect were its location not so remote. ?? 1987.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JVGR...32..287G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JVGR...32..287G"><span>The hydrothermal system of the Calabozos <span class="hlt">caldera</span>, central Chilean Andes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grunder, Anita L.; Thompson, J. Michael; Hildreth, W.</p> <p>1987-07-01</p> <p>Active thermal springs associated with the late Pleistocene Calabozos <span class="hlt">caldera</span> complex occur in two groups: the Colorado group which issues along structures related to <span class="hlt">caldera</span> collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ˜400 ppm Cl at ˜250°C by dilution with ≥50% of cold meteoric water. The thermal springs in the most deeply eroded part of the <span class="hlt">caldera</span> were derived from the same parent water by boiling. The hydrothermal system has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos hydrothermal system would be an attractive geothermal prospect were its location not so remote.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23591904','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23591904"><span>Carbonatite ring-complexes explained by <span class="hlt">caldera</span>-style volcanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria</p> <p>2013-01-01</p> <p>Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by <span class="hlt">caldera</span>-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. <span class="hlt">Caldera</span> subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic <span class="hlt">calderas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V33C2766J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V33C2766J"><span>Stable Isotopes of Tilted Ignimbrite <span class="hlt">Calderas</span> in Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, D. A.; Watts, K. E.; Hofstra, A. H.; Colgan, J. P.; Henry, C.; Bindeman, I. N.</p> <p>2013-12-01</p> <p>Mid-Tertiary <span class="hlt">calderas</span> are exceptionally well exposed in tilted fault blocks of the northern Great Basin, facilitating detailed evolutionary models of their magmatic-hydrothermal systems. The 29.4 Ma Job Canyon <span class="hlt">caldera</span>, the oldest of 3 overlapping <span class="hlt">calderas</span> in the Stillwater Range, west-central Nevada, is tilted ~90° exposing a 10-km-thick section of the crust. Large parts of the >7 km-diameter <span class="hlt">caldera</span> system, including >2 km thickness of intracaldera rhyolitic tuff, lower parts of an ~2 km thick sequence of post-<span class="hlt">caldera</span> intermediate lavas, and the upper 500 m of the resurgent granodioritic IXL pluton, were pervasively altered to propylitic, argillic, and sericitic assemblages. Sparse quartz×calcite veins cut the tuff. δ18O values of altered whole rock samples range from +4.8 to -9.1‰ but are mostly -6 to -9‰ at paleodepths >2 km. Calculated magmatic δ18O and δD values range from +6.4 to 8.2‰ and ~-70‰, respectively. Calculated fluid compositions using temperatures from fluid inclusions and mineral assemblages are δ18OH2O=-9.5 to -15‰ and δDH2O=-125 to -135‰ (chlorite) and -70 to -80‰ (epidote). Chlorite-whole rock data suggest fluids that were derived from moderately 18O-exchanged meteoric water. Fault blocks in north-central Nevada expose a >5 km upper crustal cross section through the 12-17 x 20 km, 34 Ma Caetano <span class="hlt">caldera</span>, including >3 km thickness intracaldera rhyolitic Caetano Tuff. Asymmetric <span class="hlt">caldera</span> subsidence left a depression >1 km deep partly filled with a lake. Magma resurgence and emplacement of shallow granite porphyry plutons drove a hydrothermal system that altered >120 km2 of the <span class="hlt">caldera</span> to depths >1.5 km. Alteration was focused in an early granite porphyry intrusion and surrounding upper Caetano Tuff and lacustrine sediments. Early pervasive quartz-kaolinite-pyrite alteration grades outward and downward into more restricted quartz-illite/smectite-pyrite alteration. Hematite, quartz, and barite veins and hydrothermal breccias cut</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001BVol...63..191W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001BVol...63..191W"><span>Formation of <span class="hlt">caldera</span> periphery faults: an experimental study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walter, Thomas R.; Troll, Valentin R.</p> <p>2001-06-01</p> <p>Changing stresses in multi-stage <span class="hlt">caldera</span> volcanoes were simulated in scaled analogue experiments aiming to reconstruct the mechanism(s) associated with <span class="hlt">caldera</span> formation and the corresponding zones of structural weakness. We evaluate characteristic structures resulting from doming (chamber inflation), evacuation collapse (chamber deflation) and cyclic resurgence (inflation and deflation), and we analyse the consequential fault patterns and their statistical relationship to morphology and geometry. Doming results in radial fractures and subordinate concentric reverse faults which propagate divergently from the chamber upwards with increasing dilation. The structural dome so produced is characterised bysteepening in the periphery, whereas the broadening apex subsides. Pure evacuation causes the chamber roof to collapse along adjacent bell-shaped reverse faults. The distribution of concentric faults is influenced by the initial edifice morphology; steep and irregular initial flanks result in a tilted or chaotic <span class="hlt">caldera</span> floor. The third set of experiments focused on the structural interaction of cyclic inflation and subsequent moderate deflation. Following doming, <span class="hlt">caldera</span> subsidence produces concentric faults that characteristically crosscut radial cracks of the dome. The flanks of the edifice relax, resulting in discontinuous circumferential faults that outline a structural network of radial and concentric faults; the latter form locally uplifted and tiltedwedges (half-grabens) that grade into horst-and-graben structures. This superimposed fault pattern also extends inside the <span class="hlt">caldera</span>. We suggest that major pressure deviations in magma chamber(s) are reflected in the fault arrangement dissecting the volcanoflanks and may be used as a first-order indication of the processes and mechanisms involved in <span class="hlt">caldera</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B43A0219C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B43A0219C"><span>Real-time measurements of Hg0 and H2S at La Solfatara Crater (<span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, Southern Italy) and Mt. Amiata volcano (Siena, Central Italy): a new geochemical approach to estimate the distribution of air contaminants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cabassi, J.; Calabrese, S.; Tassi, F.; Venturi, S.; Capecchiacci, F.; Di Lonardo, C.; D'Alessandro, W.; Vaselli, O.</p> <p>2014-12-01</p> <p>The emission of Hg and H2S from natural and anthropogenic sources may have a great environmental impact in urban areas as well as in the surroundings of active and passive degassing volcanoes. Mercury is present in the atmosphere mainly in its elemental form (Hg0~98 %), which has a relatively high volatility, low solubility and chemical inertness. Hydrogen sulfide, one of the most abundant gas species in volcanic fluids, is highly poisoning and corrosive. In this study, an innovative real-time method for the measurements of Hg0 and H2S concentrations in air was carried out at La Solfatara Crater, a hydrothermally altered tuff-cone nested in the town of Pozzuoli (Southern Italy), and at Mt. Amiata volcano (Central Italy), where a world-class Hg mining district abandoned in the seventies and a presently-exploited geothermal field for the production of electrical energy occur. The main aims were (i) to test this new methodological approach and (ii) to investigate Hg0 and H2S concentrations and the chemical-physical parameters regulating their spatial distribution in polluted areas. A portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) was used in combination with a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i) to measure Hg0 and H2S, respectively. The instruments were synchronized and set at high-frequency acquisition (10 sec and 1 min, respectively). Measurements were carried out along pathways (up to 12 km long) at an average speed of <10 km/h and coupled with GPS data and meteorological parameters. In selected sites, passive samplers were positioned to determine the time-integrated Hg0 and H2S concentrations to be compared with the real-time measurements. The results indicate that this approach is highly efficient and effective in providing reliable and reproducible Hg0 and H2S concentrations and can be used to identify and characterize gas emitters in different environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V13C2364Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V13C2364Z"><span>Magmatic evolution of the Ilopango <span class="hlt">Caldera</span>, El Salvador, Central America</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zezin, D.; Mann, C. P.; Hernández, W.; Stix, J.</p> <p>2010-12-01</p> <p>The Ilopango <span class="hlt">caldera</span> (16 x 13 km) is an active, long-lived magmatic system, erupting voluminous amounts of pyroclastic material numerous times over the course of its evolution. The <span class="hlt">caldera</span> is presently water filled and the most recent activity is a dome growth event in 1880. Established age constraints from extracaldera pyroclastic sequences, indicate <span class="hlt">caldera</span> forming events occur ~ every 10,000 years over the last 40,000 years. The most recent pyroclastic eruption (TBJ) is constrained to A.D. 429 erupting 70 km3 DRE of pyroclastic material. We combine major element and trace element chemistry with 40Ar/39Ar age constraints of the intracaldera domes and intracaldera pyroclastic deposits to extent the <span class="hlt">caldera</span> history. The intracaldera domes are andesitic to rhyolitic in composition (57 - 76 wt. % SiO2), some with basaltic enclaves (54 wt. % SiO2) and pyroclastic units observed inside the <span class="hlt">caldera</span> (San Agustín Pumice Breccia) are dacitic to rhyolitic in composition (69 -75 wt. % SiO2). Formation of an intracaldera andesitic dome at 359±7.9 ka provides a minimum age of <span class="hlt">caldera</span> formation and extends the <span class="hlt">caldera</span> history back ~ 320 ka years. The variable composition of the intracaldera domes, the presence of mafic enclaves in the dome lavas, mafic clasts in the TB4 plinian fall, mafic banding in the TB3 and TB2, attest to the obvious involvement of a more mafic magma The highly evolved compositions of the pyroclastic units and the volume of erupted material, point towards a large evolving magma reservoir at depth. The mafic magma may replenish the subsurface reservoir and act as a catalyst for volcanic eruption. The presence of an intracaldera lake, the regularity with which the volcano erupts and the presence of a more mafic magma are the ingredients for a catastrophic disaster. The Ilopango <span class="hlt">caldera</span>, located 10 km to the east of the capital city of San Salvador (~ 1.5 million people) poses a threat both locally and globally as demonstrated 1600 years ago as it</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5704977','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5704977"><span>Workshop on recent research in the Valles <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heiken, G.</p> <p>1985-02-01</p> <p>Over the last 5 years, there has been increased interest in the geology of the Jemez Mountains volcanic field, New Mexico. Of special interest is the Toledo-Valles <span class="hlt">caldera</span> complex, which is targeted for research coring as part of the Continental Scientific Drilling Program. The general topics covered in this workshop were (1) hydrothermal systems and rock-water interactions, (2) volcanology and structural framework of the Jemez volcanic field, (3) determining the presence or absence of melt below the Valles <span class="hlt">caldera</span>, and (4) deep coring and drilling technology. Separate abstracts were prepared for each presentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1246121','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1246121"><span>AmeriFlux US-Vcm Valles <span class="hlt">Caldera</span> Mixed Conifer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Litvak, Marcy</p> <p>2016-01-01</p> <p>This is the AmeriFlux version of the carbon flux data for the site US-Vcm Valles <span class="hlt">Caldera</span> Mixed Conifer. Site Description - The Valles <span class="hlt">Caldera</span> Mixed Conifer site is located in the 1200 km2 Jemez River basin in north-central New Mexico. Common to elevations ranging from 3040 to 2740 m in the region, the mixed conifer stand, within the entirety of the tower footprint in all directions, provides an excellent setting for studying the seasonal interaction between snow and vegetation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210148D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210148D"><span>Towards Time-Scaling of Mixing for the Campanian Ignimbrite: Systemic Variation in Sr-Isotopic Composition from Mixing Experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Campos, Cristina; Civetta, Lucia; Perugini, Diego; Dingwell, Donald B.</p> <p>2010-05-01</p> <p>Eruptions in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, the most dangerous volcanic setting in Europe, are thought to be triggered by short-term pre-eruptive mixing of trachytic to trachydacitic resident and new basaltic, trachyandesitic (=shoshonitic) magma, in shallow magma chambers (e. g. Arienzo et al, 2008, Bull. Volcanol.). Previous geochemical and volcanological data on the Campanian Ignimbrite, (>150 km3, 39 Ma), in <span class="hlt">Campi</span> <span class="hlt">Flegrei</span>, point towards a layered reservoir, which evolved from the replenishment of the magma chamber with shoshonitic magma and short-term pre-eruptive mixing between a trachytic and a phonolitic trachytic magma. With the purpose to experimentally study the mobility and homogenization of Rb-Sr isotopes in this system, we performed mixing experiments using natural phonolitic trachytic (end-member A - S. Nicola type) and trachytic (end-member B - Mondragone-type) samples, representing the two end-members involved in the origin of the Campanian Ignimbrite. Resultant glasses from a time series, ranging from 1-hour up to 1-week, under constant flow velocity (0.5 rotations per minute; after De Campos et al., 2008. Chem. Geol.), have been analysed with respect to the Rb- and Sr-systematics. Our results reveal a progressive homogenization of the contrasting Sr-isotopes towards a hybrid value. With increasing experimental duration a clear decrease in the standard deviation of isotopic ratios has been observed, reflecting progressive isotopic homogenization. Our results also support the effectiveness of mixing in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> reservoirs, in liquidus, under high temperature, before the onset of fractional crystallization. Since different eruptive events from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> can be well characterized by means of isotopic composition, the main goal for the present study will be to use experimental data and numerical modeling in order to estimate time scales of mixing associated with the eruption of the Campanian Ignimbrite, and then compare them to the several</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JVGR..147...39C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JVGR..147...39C"><span>Application of the Gauss theorem to the study of silicic <span class="hlt">calderas</span>: The <span class="hlt">calderas</span> of La Primavera, Los Azufres, and Los Humeros (Mexico)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campos-Enríquez, J. O.; Domínguez-Méndez, F.; Lozada-Zumaeta, M.; Morales-Rodríguez, H. F.; Andaverde-Arredondo, J. A.</p> <p>2005-10-01</p> <p>We explored applications (including limitations) of Gauss's theorem to the study of silicic <span class="hlt">calderas</span>. First it enables us to determine the mass deficiency from <span class="hlt">calderas</span>. Mass deficiency itself has also other potential applications. It enables to make qualitative comparisons between <span class="hlt">calderas</span>. We can use the mass deficiency to test, in a quick way and as a preliminary step to a formal gravity inversion, for the feasibility of <span class="hlt">caldera</span> types of simple geometry (i.e., piston subsidence and funnel models). This application can be done in a straightforward way, once the mass deficiency has been determined. For this purpose the mass deficiency is converted to the volume of material missing at the <span class="hlt">caldera</span>. Subsequently, for example, this volume and the respective <span class="hlt">caldera</span> diameter enable us to estimate the height of the cylinder fitting the piston subsidence model. If the obtained parameters are congruent with the known geology and geophysical information then the model may be considered further in the inversion of the gravity data for the detailed structure. Other simple models (i.e., the funnel model) can also be analyzed in this way. In particular, when working with a piston subsidence <span class="hlt">caldera</span> type, the Gauss theorem enables us to estimate the <span class="hlt">caldera</span> collapse (very difficult to obtain based on geologic information alone). These possible uses of Gauss's theorem are illustrated with the <span class="hlt">calderas</span> of La Primavera, Los Azufres, and Los Humeros <span class="hlt">caldera</span> (Mexico). The obtained mass deficiency from these <span class="hlt">calderas</span> follow the linear mass deficiency-diameter trend observed for other <span class="hlt">calderas</span>. In particular, because of their diameters and mass deficiencies, La Primavera and Krakatau <span class="hlt">calderas</span> can be considered equiparable. This comparison is of the most importance considering that La Primavera is located in the neighbourhood of a metropolis (Guadalajara City). Since geophysical studies have already established a piston subsidence model for these <span class="hlt">calderas</span>, we assessed Gauss's theorem</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3020833','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3020833"><span>Comparison of Premier <span class="hlt">CAMPY</span> Enzyme Immunoassay (EIA), ProSpecT Campylobacter EIA, and ImmunoCard STAT! <span class="hlt">CAMPY</span> Tests with Culture for Laboratory Diagnosis of Campylobacter Enteric Infections ▿ †</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Granato, Paul A.; Chen, Li; Holiday, Iris; Rawling, Russell A.; Novak-Weekley, Susan M.; Quinlan, Tammy; Musser, Kimberlee A.</p> <p>2010-01-01</p> <p>Campylobacter enteritis is a food-borne or waterborne illness caused almost exclusively by Campylobacter jejuni and, to a lesser extent, by Campylobacter coli. These organisms produce indistinguishable clinical diseases and together represent the second most common cause of bacterial diarrhea in the United States and the leading cause of enteric infection throughout the world. The conventional approach to the laboratory diagnosis of Campylobacter enteritis is based on the recovery of the organism from a stool specimen, which requires the use of a specialized medium incubated at 42°C for several days in an artificially created microaerophilic environment. Recently, several commercially available enzyme immunoassays (EIAs) have been developed for the direct detection of C. jejuni and C. coli in stool specimens. This study compared conventional culture with three EIA methods, the Premier <span class="hlt">CAMPY</span> EIA (Meridian Bioscience, Cincinnati, OH), the ProSpecT Campylobacter EIA (Remel, Lenexa, KS), and the ImmunoCard STAT! <span class="hlt">CAMPY</span> test (Meridian Bioscience, Cincinnati, OH), for the detection of C. jejuni and C. coli in 485 patient stool samples. Discordant results were arbitrated by using an in-house, real-time PCR assay that was developed and validated by a public health reference laboratory. Following analyses of the discrepant specimens by PCR, the sensitivity and specificity of both the Premier <span class="hlt">CAMPY</span> and ProSpecT Campylobacter EIAs were 99.3% and 98%, respectively, while the ImmunoCard STAT! <span class="hlt">CAMPY</span> test had a sensitivity of 98.5% and a specificity of 98.2%. By use of the PCR test as the reference standard, culture detected 127 of 135 Campylobacter-positive stool specimens, yielding a sensitivity of 94.1%. These results showed that the three EIAs evaluated in this study provide a rapid and reliable alternative for the laboratory diagnosis of enteric infections with C. jejuni and C. coli and that conventional culture may no longer be recognized as the “gold standard” for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013962','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013962"><span>RELATIONSHIP OF THE CORTEZ <span class="hlt">CALDERA</span> TO THE CORTEZ DISSEMINATED GOLD DEPOSIT, NEVADA.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rytuba, James J.; Madrid, Raul J.; McKee, E.H.</p> <p>1984-01-01</p> <p>The Cortez <span class="hlt">caldera</span> is an oval structure ten km in diameter formed by <span class="hlt">caldera</span> collapse and is located in the northern part of the Toiyabe Range, central Nevada. The Cortez gold deposit, a carbonate-hosted disseminated gold deposit, is located three km northeast of the northern margin of the Cortez <span class="hlt">caldera</span>. Dike within the Cortez gold deposit have a similar age and composition as the Caetano Tuff and strike N 30-40 degree W, subparallel to the <span class="hlt">caldera</span> margin and dip up to 45 degree toward the <span class="hlt">caldera</span>. Remnants of the outflow facies of the Caetano Tuff near the Cortez deposit indicate that the deposit formed near the Oligocene paleosurface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019704','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019704"><span>Igneous evolution of a complex laccolith-<span class="hlt">caldera</span>, the Solitario, Trans-Pecos Texas: Implications for <span class="hlt">calderas</span> and subjacent plutons</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Henry, C.D.; Kunk, M.J.; Muehlberger, W.R.; McIntosh, W.C.</p> <p>1997-01-01</p> <p>The Solitario is a large, combination laccolith and <span class="hlt">caldera</span> (herein termed "laccocaldera"), with a 16-km-diameter dome over which developed a 6 x 2 km <span class="hlt">caldera</span>. This laccocaldera underwent a complex sequence of predoming sill, laccolith, and dike intrusion and concurrent volcanism; doming with emplacement of a main laccolith; ash-flow eruption and <span class="hlt">caldera</span> collapse; intracaldera sedimentation and volcanism; and late intrusion. Detailed geologic mapping and 40Ar/39Ar dating reveal that the Solitario evolved over an interval of approximately 1 m.y. in three distinct pulses at 36.0, 35.4, and 35.0 Ma. The size, duration, and episodicity of Solitario magmatism are more typical of large ash-flow <span class="hlt">calderas</span> than of most previously described laccoliths. Small volumes of magma intruded as abundant rhyolitic to trachytic sills and small laccoliths and extruded as lavas and tuffs during the first pulse at 36.0 Ma. Emplacement of the main laccolith, doming, ash-flow eruption, and <span class="hlt">caldera</span> collapse occurred at 35.4 Ma during the most voluminous pulse. A complex sequence of debris-flow and debris-avalanche deposits, megabreccia, trachyte lava, and minor ash-flow tuff subsequently filled the <span class="hlt">caldera</span>. The final magmatic pulse at 35.0 Ma consisted of several small laccoliths or stocks and numerous dikes in <span class="hlt">caldera</span> fill and along the ring fracture. Solitario rocks appear to be part of a broadly cogenetic, metaluminous suite. Peralkaline rhyolite lava domes were emplaced north and west of the Solitario at approximately 35.4 Ma, contemporaneous with laccolith emplacement and the main pulse in the Solitario. The spatial and temporal relation along with sparse geochemical data suggest that the peralkaline rhyolites are crustal melts related to the magmatic-thermal flux represented by the main pulse of Solitario magmatism. Current models of laccolith emplacement and evolution suggest a continuum from initial sill emplacement through growth of the main laccolith. Although the Solitario</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012573','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012573"><span>Lithium in the McDermitt <span class="hlt">caldera</span>, Nevada and Oregon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Glanzman, R.K.; McCarthy, J.H.; Rytuba, J.J.</p> <p>1978-01-01</p> <p>Anomalously high concentrations of lithium in fluviatile-lacustrine sediments near McDermitt, Nevada, may constitute a potential resource. These sediments are associated with a <span class="hlt">caldera</span> about 45 km in diameter that is a result of volcanic activity, subsidence and sedimentation chiefly of Miocene age. The sediments originally were vitroclastic and now consist chiefly of authigenic zeolites, clay minerals, feldspar and quartz. Calcite occurs as thin beds, nodules and cement Gypsum is presnt but sparse. Most of the clay beds in the <span class="hlt">caldera</span> contain 0.01-0.1% Li and have well above the average Li concentration for continental clays (0.006%) (Ronov et al.1). Individual smectitic clay samples from the western and southern part of the <span class="hlt">caldera</span> contain as much as 0.65% Li and are associated with analcime and K-feldspar. Two beds, each 0.6m thick, contain 0.35% Li. Clay samples from the northern part of the <span class="hlt">caldera</span> contain as much as 0.36% Li, and are associated with clinoptilolite and erionite. The clay beds are thinner in the north; in one section a bed 0.3 m thick contains 0.36% Li, and in another section a bed 0.1 m thick contains 0.30% Li. Lithium is probably derived from volcanic material and then incorporated into the clay beds during alteration. ?? 1978.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021417','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021417"><span>Three-dimensional velocity structure of the Kilauea <span class="hlt">caldera</span>, Hawaii</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dawson, P.B.; Chouet, B.A.; Okubo, P.G.; Villasenor, A.; Benz, H.M.</p> <p>1999-01-01</p> <p>High-resolution velocity models (0.5 km resolution) of the Kilauea <span class="hlt">caldera</span> region are obtained by the tomographic inversion of both P- and S-waye arrival times. Data are from the permanent Hawaiian Volcano Observatory (HVO) seismic network, a broadband seismic network, and a temporary array of stations centered on the southern boundary of the <span class="hlt">caldera</span>. A low-velocity P-wave anomaly is imaged centered on the southeastern edge of the <span class="hlt">caldera</span>, with a velocity contrast of about 10% and a volume of 27 km3. The VP/VS model mimics the spatial extent of the P-wave anomaly, but is partitioned into two discrete anomalous volumes centered on the southern boundary of the <span class="hlt">caldera</span> and on the upper east rift of the volcano. The corresponding Poisson's ratio in these zones is high (?? = 0.25-0.32) which is consistent with a densely-cracked, hot volume which may contain partial melt. The large-scale features of the models are consistent with results obtained from an earlier, larger-scale (2 km resolution) tomographic image of Kilauea Volcano based on HVO network data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1985/0370/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1985/0370/report.pdf"><span>The Salma <span class="hlt">Caldera</span> complex, northeastern Arabian Shield, Kingdom of Saudi Arabia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kellogg, K.S.</p> <p>1985-01-01</p> <p>The upper Proterozoic Salma <span class="hlt">caldera</span> is genetically part of an elongate alkali granitic massif, Jabal Salma. Comenditic ash-flow tuffs, the oldest recognized rocks of the <span class="hlt">caldera</span> complex, were erupted during <span class="hlt">caldera</span> collapse associated with the rapid evacuation of the upper, mildly peralkaline part of a zoned magma reservoir. Within the tuff sequence, a massive, lithic-rich intracaldera tuff containing megabreccia blocks is overlain by a layered ash-flow sequence. Later peralkaline granite intruded the <span class="hlt">caldera</span> ring fracture zone. Metaluminous to peraluminous magma rose beneath the <span class="hlt">caldera</span> approximately 580 Ma ago and solidified as biotite alkali-feldspar granite, syenogranite, and granophyre. No apparent structural doming of the exposed volcanic rocks along the east side of the <span class="hlt">caldera</span> took place, and post- emplacement deformation and metamorphism of the <span class="hlt">caldera</span> are minimal.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V53A2750B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V53A2750B"><span>Magmas and reservoirs beneath the Rabaul <span class="hlt">caldera</span> (Papua New Guinea)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouvet de Maisonneuve, C.; Costa Rodriguez, F.; Huber, C.</p> <p>2013-12-01</p> <p>The area of Rabaul (Papua New Guinea) consists of at least seven - possibly nine - nested-<span class="hlt">calderas</span> that have formed over the past 200 ky. The last <span class="hlt">caldera</span>-forming eruption occurred 1400 y BP, and produced about 10 km3 of crystal-poor, two-pyroxene dacite. Since then, five effusive and explosive eruptive episodes have occurred from volcanic centres along the <span class="hlt">caldera</span> rim. The most recent of these was preceded by decade-long unrest (starting in 1971) until the simultaneous eruption of Vulcan and Tavurvur, two vents on opposite sides of the <span class="hlt">caldera</span> in 1994. Most eruptive products are andesitic in composition and show clear signs of mixing/mingling between a basalt and a high-K2O dacite. The hybridization is in the form of banded pumices, quenched mafic enclaves, and hybrid bulk rock compositions. In addition, the 1400 y BP <span class="hlt">caldera</span>-related products show the presence of a third mixing component; a low-K2O rhyodacitic melt or magma. Geochemical modeling considering major and trace elements and volatile contents shows that the high-K2O dacitic magma can be generated by fractional crystallization of the basaltic magma at shallow depths (~7 km, 200 MPa) and under relatively dry conditions (≤3 wt% H2O). The low-K2O rhyodacitic melt can either be explained by extended crystallization at low temperatures (e.g. in the presence of Sanidine) or the presence of an additional, unrelated magma. Our working model is therefore that basalts ascend to shallow crustal levels before intruding a main silicic reservoir beneath the Rabaul <span class="hlt">caldera</span>. Storage depths and temperatures estimated from volatile contents, mineral-melt equilibria and rock densities suggest that basalts ascend from ~20 km (~600 MPa) to ~7 km (200 MPa) and cool from ~1150-1100°C before intruding a dacitic magma reservoir at ~950°C. Depending on the state of the reservoir and the volumes of basalt injected, the replenishing magma may either trigger an eruption or cool and crystallize. We use evidence from major and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V32D1020A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V32D1020A"><span><span class="hlt">Calderas</span> of the Central Sector of the Mexican Volcanic Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre-Diaz, G. J.</p> <p>2001-12-01</p> <p>The central sector of the Mexican Volcanic Belt (MVB) (-99 to -103, Long W) has the largest number of <span class="hlt">calderas</span> so far identified in this province. The <span class="hlt">calderas</span> (with their age range in Ma, and distance to the Middle America Trench in km, in parenthesis) are: Amazcala (7-6, 480), Apaseo (7-6, 440), Huichapan (5-4, 420), Agustinos (5-4, 400), Amealco (5-4, 400), Macua (4-3, 410), Muerta (?, 380), Catedral (6-5, 370), Azufres (4.5-0.03, 370 -Pradal & Robin, 1994), and Zitácuaro (12-0.5, 320 -Capra et al., 1997). Most <span class="hlt">calderas</span> completed their activity in about 1 Ma, but Azufres and Zitácuaro had longer lives, mostly as post-<span class="hlt">caldera</span> lava domes and associated pyroclastic flows. Amazcala is rhyolitic, peraluminous-peralkaline, and 10x14 km in diameter. Apaseo is a 11x14 km center that started as andesitic-dacitic and ended rhyolitic and mildly peraluminous; Huichapan started with dacitic ignimbrites and ended with a major rhyolitic ignimbrite; Agustinos is a > 6 km open semi-circle structure that erupted first an andesitic ignimbrite and then a rhyolitic one; Amealco is 10 km in size and erupted a succession of three ignimbrites with mingled glasses with compositions from trachyandesite to rhyolite; Macua is a summit crater structure, 3x5 km, that erupted an unwelded rhyolitic ignimbrite; Muerta is a sector collapse <span class="hlt">caldera</span>, 4x5 km, associated to lithics-rich ignimbrite eruptions; next to Mexico-City is Catedral, a 9x6 km in diameter <span class="hlt">caldera</span> with silicic ignimbrites and rim and central lava domes, some of which erupted block-and-ash flows; Azufres has being a matter of debate, but according to Padral and Robin (1994), is a long-lived structure, about 20 km in diameter, with the major <span class="hlt">caldera</span> eruption at 4.5-3.4 Ma, and repeated dome and pyroclastic flow activity until 26 Ka ago; Zitácuaro (Capra et al., 1997) is another long-lived center, with eruptive cycles at 12 Ma (the <span class="hlt">caldera</span>-forming event), 5 Ma and 0.5 Ma (mostly domes and associated pyroclastic flows). Most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991JVGR...47..183Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991JVGR...47..183Y"><span>Structure of La Primavera <span class="hlt">caldera</span>, Jalisco, Mexico, deduced from gravity anomalies and drilling results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yokoyama, I.; Mena, M.</p> <p>1991-07-01</p> <p>Previous studies of La Primavera <span class="hlt">caldera</span> have mostly been based on surface geology and topography. Since 1980, many wells, exploring for geothermal energy, have reached depths of about 2 to 3 km at the center of the <span class="hlt">caldera</span>. The results of the drillings, together with those of the gravity surveys, provide information about the subsurface structure of the <span class="hlt">caldera</span>, and shed light on its formation. The drilling results and gravity anomalies at La Primavera <span class="hlt">caldera</span> and San Marcos, located at about 40 km distance from the <span class="hlt">caldera</span>, suggest that regional gravity anomalies can be interpreted in terms of depths of the granitic basements: the basement beneath La Primavera <span class="hlt">caldera</span> is about 3 km deep and consists of roughly the same horizon as that beneath San Marcos. The drilling results within the <span class="hlt">caldera</span> reveal that the depth of the <span class="hlt">caldera</span> fills ranges from 0.3 to 1 km at the drilling sites. The andesite basement, about 1 km deep, remains approximately horizontal, and the granitic basement has a depth of about 3 km. The surface topographies, such as the postcaldera domes, scarcely disturb the subsurface strata. The local gravity anomalies show two lows within the <span class="hlt">caldera</span> reflecting the configuration of <span class="hlt">caldera</span> bottom, two funnel-shaped depressions, one of which corresponds to a vent of the Tala tuff deduced from geological observations. The mass deficiency within the <span class="hlt">caldera</span> estimated from the gravity anomaly, satisfies the general relationship that the mass deficiency is proportional to the <span class="hlt">caldera</span> diameter cubed. This means that <span class="hlt">caldera</span> structure is three-dimensional: the larger the diameter, the deeper the funnel-shape. At present this argument may be limited to funnel-shaped <span class="hlt">calderas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JGR....99.4323F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JGR....99.4323F"><span>A geophysical-geological transect of the Silent Canyon <span class="hlt">caldera</span> complex, Pahute Mesa, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferguson, John F.; Cogbill, Allen H.; Warren, Richard G.</p> <p>1994-03-01</p> <p>Revision of lithological logs for boreholes penetrating the volcanic center at Pahute Mesa, Nevada, has led to a thorough review of the volcanic stratigraphy and geologic structure. We have combined this review with a compilation of old and newly acquired gravity and seismic travel time data, producing a unified interpretation along a northwest to sutheast profile. The analysis supports a new interpretation of the Silent Canyon <span class="hlt">caldera</span> complex. The <span class="hlt">caldera</span> is found to be more asymmetric than previously suggested, with the southeastern boundary formed by linear, high-angle normal faultsand a more gently sloping northwestern boundary. The total thickness of volcanic units within the <span class="hlt">caldera</span> complex does not appear to exceed 5 km. The shallow structure at Pahute Mesa could have a profound effect on the seismic response for regional and teleseismic signals from this nuclear test site. The Silent Canyon <span class="hlt">caldera</span> complex is actually a set of nested <span class="hlt">calderas</span> first filled by thick (greater than 1 km) postcaldera lavas and subsequently buried by outflow sheets of the Timber Mountain <span class="hlt">caldera</span> to the south. Thick, postcaldera lavas filled a half-graben structure formed west of the West Greeley fault, dropping the tops of the youngest <span class="hlt">caldera</span>-forming units to depths in excess of 2 km. Therefore the western boundary of the <span class="hlt">caldera</span> complex is poorly defined. East of the West Greeley fault, two overlapping <span class="hlt">calderas</span> are defined, and stratigraphic data suggest the presence of even older <span class="hlt">calderas</span>. The youngest <span class="hlt">caldera</span>, the calc-alkaline Area 20 <span class="hlt">caldera</span>, is well defined from drill hole data. The Area 20 <span class="hlt">caldera</span> overlaps the 13.6 Ma peralkaline Grouse Canyon <span class="hlt">caldera</span>, which is less well defined, but apparently collapsed in trap-door style along the Almendro fault. For both these <span class="hlt">calderas</span>, collapse continued after the main <span class="hlt">caldera</span>-forming eruption, concurrent with the accumulation of thick (greater than 1 km) lavas within the peripheral collapse zones. The geophysical interpretation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JGR....9011253K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGR....9011253K"><span>Root zone of the Late Proterozoic Salma <span class="hlt">Caldera</span>, northeastern Arabian Shield, Kingdom of Saudi Arabia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kellogg, Karl S.</p> <p>1985-11-01</p> <p>The eroded root of the late Proterozoic Salma <span class="hlt">caldera</span> crops out in a striking, roughly elliptical feature, about 27 km long and 22 km wide, near the northeastern edge of the Arabian Shield. The <span class="hlt">caldera</span> is genetically part of an elongate alkalic granitic massif (Jabal Salma) that extends 35 km from the <span class="hlt">caldera</span> to the southwest. Comenditic ash flow tuff and lava(?) of the <span class="hlt">caldera</span> fill, probably more than 1 km thick, are the oldest recognized rocks of the <span class="hlt">caldera</span> complex. These rocks were erupted during <span class="hlt">caldera</span> collapse associated with the rapid evacuation of the upper, mildly peralkalic part of a zoned magma reservoir. Within the <span class="hlt">caldera</span> fill, a massive, lithic-rich intracaldera rhyolite, probably a lava in excess of 1 km thick, is overlain by a layered ash flow sequence. Numerous megabreccia blocks, probably derived from the <span class="hlt">caldera</span> wall, occur in the massive rhyolite. Open folds in the layered volcanic rocks may be due to high-temperature slumping of the rocks toward the center of the <span class="hlt">caldera</span> following collapse. Later peralkalic granite that intruded the <span class="hlt">caldera</span> ring fracture zone occurs in an arcuate pattern outside the area of exposed <span class="hlt">caldera</span> fill. After <span class="hlt">caldera</span> collapse, metaluminous to peraluminous magma rose beneath the <span class="hlt">caldera</span> at approximately 580 Ma and solidified as biotite alkali granite, rim syenogranite, and late, high-level granophyre. Rare earth element abundances indicate that the layered rhyolite tuff, peralkalic granite, and granophyre are chemically more evolved than the biotite alkali granite and rim syenogranite. The granophyre intruded the <span class="hlt">caldera</span> fill as a dome-shaped body composed of numerous sheetlike masses. Granophyric texture resulted from rapid pressure release and quenching accompanying the intrusion of each sheet. Maximum penetration of the granophyre into overlying rocks occurred in the central region and along the west side of the <span class="hlt">caldera</span>, where the <span class="hlt">caldera</span> fill volcanic rocks have been removed by erosion. No apparent structural</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70187322','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70187322"><span>The volcanic, sedimentologic, and paleolimnologic history of the Crater Lake <span class="hlt">caldera</span> floor, Oregon:Evidence for small <span class="hlt">caldera</span> evolution</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nelson, C. Hans; Bacon, Charles R.; Robinson, Stephen W.; Adam, David P.; Bradbury, J. Platt; Barber, John H.; Schwartz, Deborah; Vagenas, Ginger</p> <p>1994-01-01</p> <p>Apparent phreatic explosion craters, <span class="hlt">caldera</span>-floor volcanic cones, and geothermal features outline a ring fracture zone along which Mount Mazama collapsed to form the Crater Lake <span class="hlt">caldera</span> during its climactic eruption about 6,850 yr B.P. Within a few years, subaerial deposits infilled the phreatic craters and then formed a thick wedge (10-20 m) of mass flow deposits shed from <span class="hlt">caldera</span> walls. Intense volcanic activity (phreatic explosions, subaerial flows, and hydrothermal venting) occurred during this early postcaldera stage, and a central platform of subaerial andesite flows and scoria formed on the <span class="hlt">caldera</span> floor.Radiocarbon ages suggest that deposition of Iacustrine hemipelagic sediment began on the central platform about 150 yr after the <span class="hlt">caldera</span> collapse. This is the minimum time to fill the lake halfway with water and cover the platform assuming present hydrologic conditions of precipitation and evaporation but with negligible leakage of lake water. Wizard Island formed during the final part of the 300-yr lake-filling period as shown by its (1) upper subaerial lava flows from 0 to -70 m below present water level and lower subaqueous lava flows from -70 to -500 m and by (2) lacustrine turbidite sand derived from Wizard Island that was deposited on the central platform about 350 yr after the <span class="hlt">caldera</span> collapse. Pollen stratigraphy indicates that the warm and dry climate of middle Holocene time correlates with the early lake deposits. Diatom stratigraphy also suggests a more thermally stratified and phosphate-rich environment associated respectively with this climate and greater hydrothermal activity during the early lake history.Apparent coarse-grained and thick-bedded turbidites of the early lake beds were deposited throughout northwest, southwest, and eastern basins during the time that volcanic and seismic activity formed the subaqueous Wizard Island, Merriam Cone, and rhyodacite dome. The last known postcaldera volcanic activity produced a subaqueous rhyodacite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6020332','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6020332"><span>Subsurface structure of Valles <span class="hlt">Caldera</span>; a resurgent cauldron in northern New Mexico. [Abstract only</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goff, F.</p> <p>1983-03-01</p> <p>Valles <span class="hlt">Caldera</span> is a 1.1 My old silicic cauldron lying at the intersection of the Rio Grande rift and northeast-trending Jemez Lineament. Geothermal exploration in the <span class="hlt">caldera</span> region during the last 10 years provides subsurface data which refine our knowledge of deep <span class="hlt">caldera</span> structure, but raise some questions concerning current models of resurgent cauldrons. For example, a detailed gravity investigation using 730 stations (Segar, 1974) shows a circular negative gravity anomaly centered over the <span class="hlt">caldera</span> (as expected) but also indicates a strong northeast-trending grain of fault blocks in pre-<span class="hlt">caldera</span> rocks, that are generally down-faulted to the southeast toward the Rift. Gravity data do not define a diapir structure beneath the resurgent dome attributable to tumescent magma; instead of a northeast-trending horst underlies the Redondo Peak segment of the dome. Interpretation of stratigraphy from many geothermal wells suggests that the <span class="hlt">caldera</span> and resurgent dome are floored by untilted fault blocks (Hulen and Nielson, 1982). In addition, drilling to Precambrian basement and depths of 3.2 km has not encountered a large intrusive rhyolite that might logically produce tumescence of the dome. The new data indicate that the subsurface structural configuration of Valles <span class="hlt">Caldera</span> is controlled by pre-<span class="hlt">caldera</span> tectonics and that a more complicated mechanism is required to explain the resurgent dome standing high inside the <span class="hlt">caldera</span>. A refined mechanism of resurgence might be one result of CSDP drilling at Valles <span class="hlt">Caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.V72A1299S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.V72A1299S"><span>Geochemistry of hydrothermal plume in the Suiyo Seamount <span class="hlt">Caldera</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shitashima, K.; Maeda, Y.</p> <p>2002-12-01</p> <p>Chemical compounds of the hot basalt origin are discharged into the deep ocean via hydrothermal plume by the deep-sea hydrothermal activity. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the hydrothermal plume are important to comprehend the oceanic geochemical cycles. Recently, it has been clarified that the variation of hydrothermal activity is greatly controlled in the tidal current. Not only geochemical observation but also physical observation, such as water current measurement, are necessary for the understanding of the deep-sea hydrothermal systems including the behavior of hydrothermal plume. In order to observe the diffusion process of hydrothermal plumes, sampling and chemical mapping of the hydrothermal plume and measurement of water current were carried out at the Suiyo Seamount <span class="hlt">Caldera</span> during research cruises under the ?Archaean Park? project funded by MEXT. The three-dimensional acoustic current meters were moored at the height of 13m and 125m above the bottom in the Suiyo Seamount <span class="hlt">Caldera</span>. At the 13m height, average water current speed and current direction were 10.46 cm/second and 228.1 degrees, respectively, and maximum water current speed was over 40.46 cm/second. On the other hand, average water current speed and current direction at the 125m height were 3.87 cm/second and 57.8 degrees, respectively. The strong water current of the southwest direction in 24 hours periods existed near bottom of the <span class="hlt">caldera</span>. In addition, downward current and water temperature depreciation were observed, when there was the strong current in 24 hours periods. These results suggest that the low-temperature ocean water around the Suiyo Seamount flows toward the bottom of <span class="hlt">caldera</span> periodically. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles and the in-situ pH sensor were installed on the ROV or manned submersible. The hydrothermal plume</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2016/5120/sir20165120.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2016/5120/sir20165120.pdf"><span>Long Valley <span class="hlt">Caldera</span> Lake and reincision of Owens River Gorge</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hildreth, Wes; Fierstein, Judy</p> <p>2016-12-16</p> <p>Owens River Gorge, today rimmed exclusively in 767-ka Bishop Tuff, was first cut during the Neogene through a ridge of Triassic granodiorite to a depth as great as its present-day floor and was then filled to its rim by a small basaltic shield at 3.3 Ma. The gorge-filling basalt, 200 m thick, blocked a 5-km-long reach of the upper gorge, diverting the Owens River southward around the shield into Rock Creek where another 200-m-deep gorge was cut through the same basement ridge. Much later, during Marine Isotope Stage (MIS) 22 (~900–866 ka), a piedmont glacier buried the diversion and deposited a thick sheet of Sherwin Till atop the basalt on both sides of the original gorge, showing that the basalt-filled reach had not, by then, been reexcavated. At 767 ka, eruption of the Bishop Tuff blanketed the landscape with welded ignimbrite, deeply covering the till, basalt, and granodiorite and completely filling all additional reaches of both Rock Creek canyon and Owens River Gorge. The ignimbrite rests directly on the basalt and till along the walls of Owens Gorge, but nowhere was it inset against either, showing that the basalt-blocked reach had still not been reexcavated. Subsidence of Long Valley <span class="hlt">Caldera</span> at 767 ka produced a steep-walled depression at least 700 m deeper than the precaldera floor of Owens Gorge, which was beheaded at the caldera’s southeast rim. <span class="hlt">Caldera</span> collapse reoriented proximal drainages that had formerly joined east-flowing Owens River, abruptly reversing flow westward into the <span class="hlt">caldera</span>. It took 600,000 years of sedimentation in the 26-km-long, usually shallow, <span class="hlt">caldera</span> lake to fill the deep basin and raise lake level to its threshold for overflow. Not until then did reestablishment of Owens River Gorge begin, by incision of the gorge-filling ignimbrite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6676327','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6676327"><span>Geology and eruptive mechanisms of Masaya <span class="hlt">Caldera</span> Complex, Nicaragua</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Williams, S.N.</p> <p>1983-01-01</p> <p>Results of detailed geologic field mapping and analysis of eruptive mechanisms at Masaya <span class="hlt">Caldera</span> Complex, Nicaragua are presented. Eruptions began at least 50,000 and possibly 460,000 y.b.p. The Las Sierras Formation, regarded as Plio-Pleistocene in age, forms the local basement. A central vent of group or vents in the developing Masaya volcanic complex produced diverse deposits, all of basaltic composition. Eruption of a pyroclastic flow-surge sequence at 2250-6500 y.b.p. culminated in wholesale collapse of a <span class="hlt">caldera</span> with a volume of 15.3 km/sup 3/. The bulk volume of the ignimbrite is 2.2-3.4 kkm/sup 3/ and the surge deposit is 4.9-5.5 km/sup 3/. Pre-historic lava production rates of 1.9-5.5 x 10/sup 6/ m/sup 3//year are similar to rates at other volcanoes but 26-76 times greater than the historic rate of production. The average lava effusion rate of 32 m/sup 3//sec during the 1772 eruption is at least an order of magnitude greater than observed effusion rates at other Central American volcanoes, and helps explain the unusual shield-like morphology of the volcano. Pyroclastic eruptions of several types have played an important role in the evolution of the volcano. Fissure-type eruptions, unknown elsewhere in Central America, have created numerous ash and scoria deposits. Two widespread scoria-fall deposits, locally known as the Fontana Lapilli an San Judas Formation, are the first documented plinian airfall deposts of basaltic composition. The Masaya-type <span class="hlt">caldera</span> is redefined as a <span class="hlt">caldera</span> associated with voluminous explosive eruptions of much less than 100 km/sup 3/ of mafic magma from a summit vent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17778631','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17778631"><span>Outward-dipping ring-fault structure at rabaul <span class="hlt">caldera</span> as shown by earthquake locations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mori, J; McKee, C</p> <p>1987-01-09</p> <p>The locations of a large number of earthquakes recorded at Rabaul <span class="hlt">caldera</span> in Papua New Guinea from late 1983 to mid-1985 have produced a picture of this active <span class="hlt">caldera</span>'s structural boundary. The earthquake epicenters form an elliptical annulus about 10 kilometers long by 4 kilometers wide, centered in the southern part of the Rabaul volcanic complex. A set of events with well-constrained depth determinations shows a ring-fault structure that extends from the surface to a depth of about 4 kilometers and slopes steeply outward from the center of the <span class="hlt">caldera</span>. This is the first geophysical data set that clearly outlines the orientation of an active <span class="hlt">caldera</span>'s bounding faults. This orientation, however, conflicts with the configuration of many other <span class="hlt">calderas</span> and is not in keeping with currently preferred models of <span class="hlt">caldera</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5767793','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5767793"><span>Faulting history of the Long Valley <span class="hlt">caldera</span>, eastern California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Foster, J.G. . School of Natural Science)</p> <p>1993-03-01</p> <p>The faulting history that produced the Sierra Nevada Range can be seen, in part, on the eastern contact of the Sierra Nevada Block with the Owens Valley Block. By surveying a series of remnant lake shore lines in the Long Valley <span class="hlt">Caldera</span> of eastern California, the deformation and faulting history of the area can be inferred. These beaches are ideal for studying the faulting history of the area as their location is so near the contact of the two plates. The <span class="hlt">caldera</span> sits on the Owens Valley Block just east of the major fault which separates it from the Sierra Nevada Block. It encompasses a ten mile by twenty mile area, which was filled with a lake after its creation some 730,000 years ago. Over time, the lake slowly lowered due to erosion of its sill, successive upward tilting of the Sierra Nevada Block, and consequent downward tilting of the Owens Valley Block. These changes in the attitude of the <span class="hlt">caldera</span> floor and the beaches of the lake left the successive, non-parallel shore lines that have now been surveyed, mapped, and dated relative to each other. Together with the regional structures and history of the area, the remnant deformed shore lines can be used to develop a picture of the faulting history of the area and its relation to the rising of the Sierra Nevada Mountains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16511491','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16511491"><span>Uplift, thermal unrest and magma intrusion at Yellowstone <span class="hlt">caldera</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wicks, Charles W; Thatcher, Wayne; Dzurisin, Daniel; Svarc, Jerry</p> <p>2006-03-02</p> <p>The Yellowstone <span class="hlt">caldera</span>, in the western United States, formed approximately 640,000 years ago when an explosive eruption ejected approximately 1,000 km3 of material. It is the youngest of a series of large <span class="hlt">calderas</span> that formed during sequential cataclysmic eruptions that began approximately 16 million years ago in eastern Oregon and northern Nevada. The Yellowstone <span class="hlt">caldera</span> was largely buried by rhyolite lava flows during eruptions that occurred from approximately 150,000 to approximately 70,000 years ago. Since the last eruption, Yellowstone has remained restless, with high seismicity, continuing uplift/subsidence episodes with movements of approximately 70 cm historically to several metres since the Pleistocene epoch, and intense hydrothermal activity. Here we present observations of a new mode of surface deformation in Yellowstone, based on radar interferometry observations from the European Space Agency ERS-2 satellite. We infer that the observed pattern of uplift and subsidence results from variations in the movement of molten basalt into and out of the Yellowstone volcanic system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V53C2637L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V53C2637L"><span>Long Period Tremor At Sierra Negra <span class="hlt">Caldera</span>, Galapagos</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lees, J. M.; Ebinger, C. J.; Ruiz, M. C.</p> <p>2011-12-01</p> <p>Galapagos <span class="hlt">caldera</span> have exhibited extremely high amplitude, short time-scale surface deformations as observed in high spatial resolution InSAR along the 7 active volcanoes archipelago, and high temporal resolution GPS on Sierra Negra. A temporary array of 16 seismic stations was installed to monitor the seismic behavior on a regional scale. Several stations were deployed in and around the <span class="hlt">caldera</span> to understand the seismic response of the modeled sill below the current lava surface. Occasional bursts of low frequency (5s) tremor have been recorded on several stations in the <span class="hlt">caldera</span> and rim zone. The tremor clearly rises above background microseismic noise with an ovate, or Gaussian, envelope. Frequency analysis shows that the tremor exhibits frequency gliding, from slightly below 5s to slightly above, over a time span of several minutes. We presume these transient tremor episodes have a fluid dynamic origin, either hydrothermal or magmatic. The oscillatory bursts differ significantly from tremor observed at other, more silicic, volcanoes where explosions and degassing prevail. We place these events within the volcanological context afforded by seismic, geodetic, and gas emission studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030222','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030222"><span>Uplift, thermal unrest and magma intrusion at Yellowstone <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wicks, Charles W.; Thatcher, Wayne; Dzurisin, Daniel; Svarc, Jerry</p> <p>2006-01-01</p> <p>The Yellowstone <span class="hlt">caldera</span>, in the western United States, formed 640,000 years ago when an explosive eruption ejected 1,000 km3 of material1. It is the youngest of a series of large <span class="hlt">calderas</span> that formed during sequential cataclysmic eruptions that began 16 million years ago in eastern Oregon and northern Nevada. The Yellowstone <span class="hlt">caldera</span> was largely buried by rhyolite lava flows during eruptions that occurred from 150,000 to 70,000 years ago1. Since the last eruption, Yellowstone has remained restless, with high seismicity, continuing uplift/subsidence episodes with movements of 70 cm historically2 to several metres since the Pleistocene epoch3, and intense hydrothermal activity. Here we present observations of a new mode of surface deformation in Yellowstone, based on radar interferometry observations from the European Space Agency ERS-2 satellite. We infer that the observed pattern of uplift and subsidence results from variations in the movement of molten basalt into and out of the Yellowstone volcanic system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013199','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013199"><span>On the formation of <span class="hlt">calderas</span> during ignimbrite eruptions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Druitt, T.H.; Sparks, R.S.J.</p> <p>1984-01-01</p> <p>Many large <span class="hlt">calderas</span> result from the eruption of substantial volumes (tens or hundreds of km3) of silicic pyroclastics. Such events often begin with an airfall phase and progress to the generation of voluminous ignimbrites1-3. We propose here that many such eruptions involve two well-defined stages, based on a simple analysis of magma chamber pressure variations during an eruption. The first stage begins when an overpressured magma chamber fractures the country rock and forms a conduit to the surface. The chamber pressure decreases rapidly to values less than lithostatic pressure. We show that only small to moderate volumes of magma, representing a small fraction of the total chamber, can be erupted during this stage. In the second stage, <span class="hlt">caldera</span> collapse results from a further decrease in magma pressure, which causes the chamber roof to fracture catastrophically and deform. Subsidence of the roof attempts to re-establish lithostatic pressures within the chamber and can drive substantial volumes of magma to the surface. Geological relationships in pyroclastic deposits associated with large <span class="hlt">caldera</span> eruptions provide independent evidence for this model. ?? 1984 Nature Publishing Group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6564207','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6564207"><span>Preliminary Hot Dry Rock geothermal evaluation of Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gambill, D.T.</p> <p>1981-03-01</p> <p>Long Valley <span class="hlt">Caldera</span>, formed during the catastrophic eruption of the Bishop Tuff 0.7 Myr ago, straddles the border between the Sierra Nevada and the Basin and Range tectonic provinces in eastern California. The <span class="hlt">caldera</span> contains rhyolitic to basaltic flows, tuffs, and domes from 3.2 Myr to 450 yr old. Sierra Nevada frontal faults intersect the northwest and southeast parts of the <span class="hlt">caldera</span>. The dominant feature within the <span class="hlt">caldera</span> is a resurgent dome in the west-central section, which formed between about 0.7 and 0.5 Myr b.p. Teleseismic data indicate a low P-wave velocity zone below the western part of the <span class="hlt">caldera</span>, indicating a magma chamber between 7 and 25 km depth. This conclusion is supported by gravity data. Heat flow just west of the <span class="hlt">caldera</span> is 3.75 HFU. Just east of the <span class="hlt">caldera</span>, measured heat flow is about 2 HFU. However, a deep well on the eastern edge of the resurgent dome has a gradient of 38/sup 0/C/km from 0.66 to 1.2 km suggesting that the magma chamber, which produced Long Valley, is largely crystallized below the resurgent dome. The high heat flow beneath the western <span class="hlt">caldera</span> may be a manifestation of shallow silicic magma associated with the recent Inyo Craters. These data indicate a smaller magma source may lie below the western <span class="hlt">caldera</span>. The resurgent dome and the area just west of the <span class="hlt">caldera</span> are cited for additional Hot Dry Rock prospection. The higher temperature gradient and lack of <span class="hlt">caldera</span> fill beyond the west margin of the <span class="hlt">caldera</span> combine to make this area promising for future HDR evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6500217','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6500217"><span>A core hole in the southwestern moat of the Long Valley <span class="hlt">caldera</span>: Early results</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wollenberg, H.A.; Sorey, M.L.; Farrar, C.D.; White, A.F.; Flexser, S.; Bartel, L.C.</p> <p>1986-12-01</p> <p>A continuously cored hole penetrated 715m into the southwestern moat of the Long Valley <span class="hlt">caldera</span>. Temperatures in the post-<span class="hlt">caldera</span> deposits increase rapidly with depth over the upper 335m to 202/sup 0/C, then remain nearly isothermal into the Bishop Tuff to the bottom of the hole. The depth to the Bishop is the shallowest, and the temperatures observed are among the highest in holes drilled in the <span class="hlt">caldera</span>. The hole identifies a potential geothermal resource for the community of Mammoth Lakes, constrains the position of the principal heat source for the <span class="hlt">caldera</span>'s hydrothermal system, and serves as access for monitoring changes in water level, temperatures, and fluid chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JVGR..245...21U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JVGR..245...21U"><span>Volcanological evolution and <span class="hlt">caldera</span> forming eruptions of Mt. Nemrut (Eastern Turkey)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ulusoy, İnan; Çubukçu, H. Evren; Aydar, Erkan; Labazuy, Philippe; Ersoy, Orkun; Şen, Erdal; Gourgaud, Alain</p> <p>2012-11-01</p> <p>Mt. Nemrut volcano, situated at the west of Lake Van, is one of the historically active volcanoes of the Eastern Anatolia. It has an 8.5 × 7 km diameter summit <span class="hlt">caldera</span>. Volcanic activity of Mt. Nemrut started ~ 1 Ma ago; the most recent eruptions were in 1441, 1597 and 1692 A.D. Among the Eastern Anatolian volcanoes, Mt. Nemrut is the most hazardous volcano for its vicinity. Present day volcanic activity is represented by intra-<span class="hlt">caldera</span> hydrothermal and fumarolic output and low-level volcano-seismic events. Geological evolution and chronostratigraphy of the volcano is subdivided in three stages: pre-<span class="hlt">caldera</span>, syn-<span class="hlt">caldera</span> and post-<span class="hlt">caldera</span> stages. Pre-<span class="hlt">caldera</span> products are dominated by felsic lava flows and domes. Trachytic Nemrut and Kantaşı pyroclastics represent the <span class="hlt">caldera</span> forming activity, of which sequences are composed of fallout units and ignimbrite flows. Both Nemrut and Kantaşı ignimbrite units are low-aspect ratio ignimbrites, they are generally densely welded and present columnar jointed outcrops locally. Extent of Nemrut ignimbrite (volume: 32.6 km3) is greater than the Kantaşı ignimbrite (volume: 3.8 km3). Post-<span class="hlt">caldera</span> activity of the volcano is marked by peralkaline rhyolitic (comendite) intra-<span class="hlt">caldera</span> lava flows and explosive hydrovolcanic activities. Historical activity of the volcano is represented by bimodal basaltic-rhyolitic effusive activity along Nemrut rift zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9974388','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9974388"><span>A kuroko-type polymetallic sulfide deposit in a submarine silicic <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iizasa; Fiske; Ishizuka; Yuasa; Hashimoto; Ishibashi; Naka; Horii; Fujiwara; Imai; Koyama</p> <p>1999-02-12</p> <p>Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine <span class="hlt">caldera</span>. The sulfide body is located on the <span class="hlt">caldera</span> floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front <span class="hlt">caldera</span> raises the possibility that the numerous unexplored submarine silicic <span class="hlt">calderas</span> elsewhere might have similar deposits.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9774269','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9774269"><span>Migration of fluids beneath yellowstone <span class="hlt">caldera</span> inferred from satellite radar interferometry</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wicks; Thatcher; Dzurisin</p> <p>1998-10-16</p> <p>Satellite interferometric synthetic aperture radar is uniquely suited to monitoring year-to-year deformation of the entire Yellowstone <span class="hlt">caldera</span> (about 3000 square kilometers). Sequential interferograms indicate that subsidence within the <span class="hlt">caldera</span> migrated from one resurgent dome to the other between August 1992 and August 1995. Between August 1995 and September 1996, the <span class="hlt">caldera</span> region near the northeast dome began to inflate, and accompanying surface uplift migrated to the southwest dome between September 1996 and June 1997. These deformation data are consistent with hydrothermal or magmatic fluid migration into and out of two sill-like bodies that are about 8 kilometers directly beneath the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999BVol...61..174K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999BVol...61..174K"><span>Erosion <span class="hlt">calderas</span>: origins, processes, structural and climatic control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karátson, Dávid; Thouret, Jean-Claude; Moriya, Ichio; Lomoschitz, Alejandro</p> <p></p> <p>The origin and development of erosion-modified, erosion-transformed, and erosion-induced depressions in volcanic terrains are reviewed and systematized. A proposed classification, addressing terminology issues, considers structural, geomorphic, and climatic factors that contribute to the topographic modification of summit or flank depressions on volcanoes. Breaching of a closed crater or <span class="hlt">caldera</span> generated by volcanic or non-volcanic processes results in an outlet valley. Under climates with up to 2000-2500mm annual rainfall, craters, and <span class="hlt">calderas</span> are commonly drained by a single outlet. The outlet valley can maintain its dominant downcutting position because it quickly enlarges its drainage basin by capturing the area of the primary depression. Multi-drained volcanic depressions can form if special factors, e.g., high-rate geological processes, such as faulting or glaciation, suppress fluvial erosion. Normal (fluvial) erosion-modified volcanic depressions the circular rim of which is derived from the original rim are termed erosion craters or erosion <span class="hlt">calderas</span>, depending on the pre-existing depression. The resulting landform should be classed as an erosion-induced volcanic depression if the degradation of a cluster of craters produces a single-drained, irregular-shaped basin, or if flank erosion results in a quasi-closed depression. Under humid climates, craters and <span class="hlt">calderas</span> degrade at a faster rate. Mostly at subtropical and tropical ocean-island and island-arc volcanoes, their erosion results in so-called amphitheater valleys that develop under heavy rainfall (> 2500mm/year), rainstorms, and high-elevation differences. Structural and lithological control, and groundwater in ocean islands, may in turn preform and guide development of high-energy valleys through rockfalls, landsliding, mudflows, and mass wasting. Given the intense erosion, amphitheater valleys are able to breach a primary depression from several directions and degrade the summit region at a high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V13G2694M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V13G2694M"><span>Relating seismic swarms and deformation in Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montgomery-Brown, E. K.; Ellsworth, W. L.; Hill, D. P.; Shelly, D. R.; Langbein, J. O.; Lisowski, M.; Llenos, A. L.</p> <p>2013-12-01</p> <p>Earthquake swarm activity in the South Moat Seismic Zone (SMSZ) in Long Valley <span class="hlt">caldera</span> began increasing following the onset of slow inflation of the resurgent dome in 2011. From 1980 through 1999 the <span class="hlt">caldera</span> produced recurring earthquake swarms in the SMSZ accompanied by an 80-cm uplift of the resurgent dome. Since 2000, the <span class="hlt">caldera</span> has been quieter than from 1980 to 1999, but it experienced a gradual 7-cm uplift episode in 2002-2003 and currently the <span class="hlt">caldera</span> has been gradually uplifting since 2011 at less than half of the peak uplift velocity observed in the late 1990's. Two of the recent swarms in October/November of 2012 and March 2013 have been accompanied by small deformation transients during which <span class="hlt">caldera</span> uplift paused for about a week despite otherwise steady inflation. To better understand this recent activity, we cross correlate seismic velocity waveforms from individual events recorded by the Long Valley seismic network to identify similar clusters (families) of earthquakes and analyze their temporal recurrence. Then, we use representative waveforms from each family as templates to search the continuous waveforms from the deep borehole seismometers in the Long Valley Exploratory Well (MDH1) for repeating, yet smaller, earthquakes. MDH1 consists of two three-component instruments, located 2592 m and 2263 m below ground level, that provide 6 channels with very low background noise relative to surface seismometers. The cross correlations identify about 25 times more earthquakes with most magnitudes ranging from -1 to +0.5, determined from an empirical relationship between catalog magnitude and observed amplitude on MDH1. We apply an ETAS model to the augmented catalog to detect subtle changes in background earthquake rates that might suggest a change in stressing rate. For comparison with the change in seismicity rates, a geodetically determined stress change is estimated from a simple model of the continuous GPS data. We model the uplift from 2011 to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ngmdb.usgs.gov/Prodesc/proddesc_85260.htm','USGSPUBS'); return false;" href="http://ngmdb.usgs.gov/Prodesc/proddesc_85260.htm"><span>Geologic Map of Mount Mazama and Crater Lake <span class="hlt">Caldera</span>, Oregon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bacon, Charles R.</p> <p>2008-01-01</p> <p>Crater Lake partly fills one of the most spectacular <span class="hlt">calderas</span> of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse <span class="hlt">caldera</span>. Because of excellent preservation and access, Mount Mazama, Crater Lake <span class="hlt">caldera</span>, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the <span class="hlt">caldera</span> wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP51C1103R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP51C1103R"><span>Geophysical expression of <span class="hlt">caldera</span> related volcanism, structures and mineralization in the McDermitt volcanic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rytuba, J. J.; Blakely, R. J.; Moring, B.; Miller, R.</p> <p>2013-12-01</p> <p>The High Rock, Lake Owyhee, and McDermitt volcanic fields, consisting of regionally extensive ash flow tuffs and associated <span class="hlt">calderas</span>, developed in NW Nevada and SE Oregon following eruption of the ca. 16.7 Ma Steens flood basalt. The first ash flow, the Tuff of Oregon Canyon, erupted from the McDermitt volcanic field at 16.5Ma. It is chemically zoned from peralkaline rhyolite to dacite with trace element ratios that distinguish it from other ash flow tuffs. The source <span class="hlt">caldera</span>, based on tuff distribution, thickness, and size of lithic fragments, is in the area in which the McDermitt <span class="hlt">caldera</span> (16.3 Ma) subsequently formed. Gravity and magnetic anomalies are associated with some but not all of the <span class="hlt">calderas</span>. The White Horse <span class="hlt">caldera</span> (15.6 Ma), the youngest <span class="hlt">caldera</span> in the McDermitt volcanic field has the best geophysical expression, with both aeromagnetic and gravity lows coinciding with the <span class="hlt">caldera</span>. Detailed aeromagnetic and gravity surveys of the McDermitt <span class="hlt">caldera</span>, combined with geology and radiometric surveys, provides insight into the complexities of <span class="hlt">caldera</span> collapse, resurgence, post collapse volcanism, and hydrothermal mineralization. The McDermitt <span class="hlt">caldera</span> is among the most mineralized <span class="hlt">calderas</span> in the world, whereas other <span class="hlt">calderas</span> in these three Mid Miocene volcanic fields do not contain important hydrothermal ore deposits, despite having similar age and chemistry. The McDermitt <span class="hlt">caldera</span> is host to Hg, U, and Li deposits and potentially significant resources of Ga, Sb, and REE. The geophysical data indicate that post-<span class="hlt">caldera</span> collapse intrusions were important in formation of the hydrothermal systems. An aeromagnetic low along the E <span class="hlt">caldera</span> margin reflects an intrusion at a depth of 2 km associated with the near-surface McDermitt-hot-spring-type Hg-Sb deposit, and the deeper level, high-sulfidation Ga-REE occurrence. The Li deposits on the W side of the <span class="hlt">caldera</span> are associated with a series of low amplitude, small diameter aeromagnetic anomalies that form a continuous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913980D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913980D"><span>Decoding micro-structural damage related to <span class="hlt">caldera</span> collapse at Santorini Volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drymoni, Kyriaki; Browning, John; Gudmundsson, Agust; Mitchell, Thomas</p> <p>2017-04-01</p> <p>Deformation in damage zones, as micro fracture density, can be estimated at a given distance from a fault as a function of fault displacement, based on empirical relationships derived from detailed quantitative field studies of natural faults that cut through low porosity, crystalline rocks in strike-slip tectonic environments. For the first time, we attempt to apply the same method to study the characteristics of a damage zone generated by <span class="hlt">caldera</span> collapse along a bounding circumferential ring-fault. We have undertaken a field campaign at Santorini Volcano, Greece, and mapped sections of a dyke swarm in the northern <span class="hlt">caldera</span> wall. The dykes, associated lavas, and eruptive units are partially cut by a series of historic <span class="hlt">caldera</span> collapses. The dykes represent elastic inclusions in an otherwise heterogeneous and complex edifice which makes up the Santorini Volcano. To study <span class="hlt">caldera</span>-related damage we sampled dykes at varying distance from the inferred <span class="hlt">caldera</span> fault. The collected samples were cut into several different orientations to map micro-fracture density and orientation with relation to the strike of the historic <span class="hlt">caldera</span> faults. In addition, benchtop ultrasonic wave velocity measurements were made on all samples. Preliminary fracture analysis of plagioclase crystals and velocity data suggests relationship between proximity to the fault and micro-fracture density. We also find a mechanical anisotropy control which may relate to the orientation of fractures generated by historic <span class="hlt">caldera</span> collapses on Santorini. An analysis of the anisotropy and micro-fractures may help to identify the mechanism of <span class="hlt">caldera</span> faulting at Santorini (e.g. near-surface tension fractures and normal faulting or reverse faulting). In addition to our micro-structural study, we will investigate the presence of hydrothermal/chemical alteration within the inferred <span class="hlt">caldera</span> damage zone. Our aim is to set up numerical models to investigate stress distribution within the dykes and host rock during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.nbmg.unr.edu/dox/dox.htm','USGSPUBS'); return false;" href="http://www.nbmg.unr.edu/dox/dox.htm"><span>Geologic map of the Caetano <span class="hlt">caldera</span>, Lander and Eureka counties, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Colgan, Joseph P.; Henry, Christopher D.; John, David A.</p> <p>2011-01-01</p> <p>The Eocene (34 Ma) Caetano <span class="hlt">caldera</span> in north-central Nevada offers an exceptional opportunity to study the physical and petrogenetic evolution of a large (20 km by 10–18 km pre-extensional dimensions) silicic magma chamber, from precursor magmatism to <span class="hlt">caldera</span> collapse and intrusion of resurgent plutons. <span class="hlt">Caldera</span>-related rocks shown on this map include two units of crystal-rich intracaldera tuff totaling over 4 km thickness, <span class="hlt">caldera</span> collapse breccias, tuff dikes that fed the eruption, hydrothermally altered post-eruption rocks, and two generations of resurgent granitic intrusions (John et al., 2008). The map also depicts middle Miocene (about 16–12 Ma) normal faults and synextensional basins that accommodated >100 percent extension and tilted the <span class="hlt">caldera</span> into a series of ~40° east-dipping blocks, producing exceptional 3-D exposures of the <span class="hlt">caldera</span> interior (Colgan et al., 2008). This 1:75,000-scale map is a compilation of published maps and extensive new mapping by the authors (fig. 1), and supersedes a preliminary 1:100,000-scale map published by Colgan et al. (2008) and John et al. (2008). New mapping focused on the margins of the Caetano <span class="hlt">caldera</span>, the distribution and lithology of rocks within the <span class="hlt">caldera</span>, and on the Miocene normal faults and sedimentary basins that record Neogene extensional faulting. The definition of geologic units and their distribution within the <span class="hlt">caldera</span> is based entirely on new mapping, except in the northern Toiyabe Range, where mapping by Gilluly and Gates (1965) was modified with new field observations. The distribution of pre-Cenozoic rocks outside the <span class="hlt">caldera</span> was largely compiled from existing sources with minor modifications, with the exception of the northeastern <span class="hlt">caldera</span> margin (west of the Cortez Hills Mine), which was remapped in the course of this work and published as a stand-alone 1:6000-scale map (Moore and Henry, 2010).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JVGR..136...71U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JVGR..136...71U"><span>Volcanic and deformation history of the Bodrum resurgent <span class="hlt">caldera</span> system (southwestern Turkey)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ulusoy, I.; Cubukcu, E.; Aydar, E.; Labazuy, P.; Gourgaud, A.; Vincent, P. M.</p> <p>2004-08-01</p> <p>The volcanic rocks of the Bodrum Peninsula, in SW Turkey and NE of the Hellenic Arc, outcrop over an area of 138 km 2. A monzonitic intrusion is exposed in the western part of the peninsula. Upper Miocene volcanism is represented by high-K (HK)-andesitic, andesitic lava flows and pillows, sparse HK-andesitic and dacitic lava domes and associated block-and-ash flows. A HK-andesitic ignimbrite sequence with two stratigraphic units is associated with the collapse of a complex <span class="hlt">caldera</span> system. Breccias, formed as a result of slumping of the <span class="hlt">caldera</span> walls are observed inside the <span class="hlt">caldera</span>. Post-<span class="hlt">caldera</span> activity is represented by HK-andesitic, HK-basaltic andesitic lava flows, domes and associated block-and-ash flows. Numerous dykes, HK-andesitic and shoshonitic in composition cut all volcanic units. The structure of the Bodrum <span class="hlt">caldera</span> was investigated using SPOT image, digital elevation model (DEM), aerial photographs as well as field data. The Bodrum <span class="hlt">caldera</span> is a NE-SW-elongated, semi-elliptical, deeply eroded <span class="hlt">caldera</span> with dimensions of 18.7×7.7 km. It is partly submerged in the SW part. The complex <span class="hlt">caldera</span> system can be described in terms of two structural domains. The collapse of the Dagbelen domain is interpreted as a piston type subsidence, while the Karakaya domain represents a piecemeal collapse. Both domains exhibit two separate resurgence events. The elongation of the <span class="hlt">caldera</span> may be related to pre-existing regional tectonic structures. The <span class="hlt">caldera</span> is also affected and cut by late stage faults related to regional extensional events. Moreover, pre-<span class="hlt">caldera</span> volcanism is dispersed and cannot be related to a pre-existing stratovolcano. Bodrum volcanism is therefore interpreted as a complex ignimbritic shield volcano.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5858768','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5858768"><span>Satellites images, digitized topography, and the recognition of the Xela <span class="hlt">Caldera</span>, Quezaltenango Valley, Guatemala</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Foley, D. . Dept. of Earth Sciences); McEwen, A.; Duffield, W. ); Heiken, G. )</p> <p>1992-01-01</p> <p>The authors propose, based on reconnaissance geology studies and interpretation of landforms as depicted by Landsat Thematic Mapper (TM) images combined with digitized topography, that the Quezaltenango basin of Guatemala is part of a <span class="hlt">caldera</span>. The Quezaltenango basin is an elliptical depression, about 12 by 25 km and about 500 m deep. The proposed Xela <span class="hlt">Caldera</span> extends beyond the basin more than 10 km to the north. The geomorphological features of the area that are typical of a geologically young large-scale <span class="hlt">caldera</span> include bounding walls that have steep interior and gentle exterior slopes; broad flat areas at the base of the walls; at least one large block, about 3 by 12 km, that only partly floundered as the <span class="hlt">caldera</span> collapsed; resurgence of a younger volcanic dome, flow and small-scale <span class="hlt">caldera</span> complex (last active in 1818); younger volcanoes located along the structural margin of the major <span class="hlt">caldera</span> (one of which is currently active) lobate features on the <span class="hlt">caldera</span> margins that may indicate a multiple sequence of eruptions; and an active, high-temperature geothermal system. The valley is coincident with a gravity low. Extensive ash-flow tuff sheets that have no identified source are located north of the <span class="hlt">caldera</span>, and may be the outflow deposits. The Xela <span class="hlt">caldera</span> is similar in size to the Atitlan <span class="hlt">caldera</span>, which lies about 50 km southeast of Quezaltenango. The Xela <span class="hlt">Caldera</span>, if confirmed by future studies, may contain undiscovered geothermal resources, may present a significant geologic hazard to the more than 400,000 people who occupy the Quezaltenango valley, and may be a new member of the list of magmatic systems that have the capability to change global climate for several years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/ds/523/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/ds/523/"><span>Temperature data from wells in Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Farrar, Christopher; DeAngelo, Jacob; Williams, Colin; Grubb, Frederick; Hurwitz, Shaul</p> <p>2010-01-01</p> <p>The 30-by-20-km Long Valley <span class="hlt">Caldera</span> (LVC) in eastern California (fig.1) formed at 0.76 Ma in a cataclysmic eruption that resulted in the deposition of 600 km? of Bishop Tuff outside the <span class="hlt">caldera</span> rim (Bailey, 1989). By approximately 0.6 Ma, uplift of the central part of the <span class="hlt">caldera</span> floor and eruption of rhyolitic lava formed the resurgent dome. The most recent eruptive activity in the area occurred approximately 600 yr ago along the Mono-Inyo craters volcanic chain (Bailey, 2004; Hildreth, 2004). LVC hosts an active hydrothermal system that includes hot springs, fumaroles, mineral deposits, and an active geothermal well field and power plant at Casa Diablo along the southwestern boundary of the resurgent dome (Sorey and Lewis, 1976; Sorey and others, 1978; Sorey and others, 1991). Electric power generation began in 1985 with about 10 Mwe net capacity and was expanded to about 40 Mwe (net) in 1991 (Campbell, 2000; Suemnicht and others, 2007). Plans for further expansion are focused mainly on targets in the <span class="hlt">caldera?s</span> western moat (Sass and Priest, 2002) where the most recent volcanic activity has occurred (Hildreth, 2004). LVC has been the site of extensive research on geothermal resources and volcanic hazards (Bailey and others, 1976; Muffler and Williams, 1976; Miller and others, 1982; Hill and others 2002). The first geothermal exploratory drilling was done in the shallow (< 200 m deep) hydrothermal system at Casa Diablo in the 1960?s (McNitt, 1963). Many more boreholes were drilled throughout the <span class="hlt">caldera</span> in the 1970?s and 1980?s by private industry for geothermal exploration and by the U.S. Geological Survey (USGS) and Sandia National Laboratory for volcanic and geothermal research and exploration. Temperature logs were obtained in some of these wells during or immediately following drilling, before thermal equilibration was complete. Most of the temperature logs, however, were obtained weeks, months, or years after well completion and are representative of dynamic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR51B2709M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR51B2709M"><span>The effect of geothermal fluid composition in lime-pozzolan reactions on elastic and transport properties.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacFarlane, J.; Vanorio, T.</p> <p>2016-12-01</p> <p>Calcium-Silicate-Hydrates (C-S-H) are a complex family of hydrates known to form within hyper-alkaline geothermal systems as well as concrete. Within both environments the formation of C-S-H can be linked to the lime-pozzolan reaction. Pozzolan's defined as a siliceous or alumino-siliceous material, which in itself possesses little or no cementing property, but in the presence of moisture chemically reacts with calcium hydroxide at ordinary temperatures to form cementitious compounds. C-S-H fibers have been discovered in a low permeability, caprock layer beneath the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> <span class="hlt">caldera</span>, as well as within ancient Roman concrete made using volcanic ash and fluids from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> region over 2000 years ago. By replicating the recipe for Roman concrete, fibrous minerals have been formed in laboratory experiments and imaged using a scanning electron microscope. The formation of C-S-H within concrete has been shown to depend on the mineral ions present, among other factors. Here, we report on how the geothermal fluid composition effects the elastic and transport properties of laboratory samples. Samples were made using the same volcanic ash as the Romans, called Pozzolana, slaked lime and geothermal fluid. Two geothermal fluids from the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> region were compared, as well as deionized water as a control. Preliminary results have shown changes in both the elastic and transport properties between sample sets made with geothermal fluid and the control. These changes are attributed to the structure of the C-S-H that forms in the lime-pozzolan reaction. Understanding how the geothermal fluid composition controls the properties of this reaction has implications for the understanding of both geothermal systems and concrete engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T43B3005E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T43B3005E"><span>Elastic and Transport Properties of Steam-Cured Pozzolanic-Lime Rock Composites Upon CO2 Injection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Emery, D. E.; Vanorio, T.</p> <p>2015-12-01</p> <p>Understanding the relationship between pozzolanic ash-lime reactions and the rock physics properties of the resulting rock microstructure is important for monitoring unrest conditions in volcanic-hydrothermal systems as well as devising concrete with enhanced performance. The recent discovery in the depths of the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> volcanic-hydrothermal systems of a natural process forming a fiber-reinforced, concrete-like rock with enhanced elastic and strength properties calls for further research to investigate the physico-chemical conditions contributing to undermine or enhance the properties of the subsurface rocks of volcanic-hydrothermal systems and, in turn, build upon those processes that the ancient Romans unwittingly exploited to create their famous concrete. To study this, we prepared 8 samples by mixing the pozzolana volcanic ash, slaked lime, aggregates of Neapolitan Yellow tuff, and seawater from <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> in the same ratios as the ancient Romans. Each sample contained a lime-to-pozzolana ratio of 1:2 by weight and a water-to-binder (pozzolana plus lime) ratio of 0.4 by weight. Neapolitan Yellow tuff made up 20% of the weight of the mixture. To mimic the conditions of the <span class="hlt">caldera</span>, we used mineral seawater from a well in the <span class="hlt">Campi</span> <span class="hlt">Flegrei</span> region rich in sulfate, bicarbonate, calcium, potassium, and magnesium ions. The samples were cured under steam conditions as well. We measured baseline properties of porosity, permeability, and the acoustic velocity through the samples in order to calculate the bulk, shear, and Young's modulus. Subsequently, half of the samples were injected with CO2- rich aqueous solution and the changes in their microstructure and physical properties measured. Our findings show how a steam- and sulfur-alkaline- rich environment affects both transport and elastic properties of the samples and how they may change in response to microstructural changes due to potential chemical instabilities such as possible new flux of CO2 into a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.P41A0227G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.P41A0227G"><span>Implications of a <span class="hlt">Caldera</span> Origin of the Lunar Crater Copernicus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Green, J.</p> <p>2007-12-01</p> <p>The forthcoming renaissance in lunar exploration will focus on many objectives such as Copernicus. Copernicus appears to be a <span class="hlt">caldera</span> for at least 8 reasons. If a <span class="hlt">caldera</span> we see (1) transient activity (2) no overturned impact flap at the crater margins (3) internal sinuous leveed lava flow channels (4) a lava covered floor (5) terraces of different ages (6) multiple central volcanoes, one showing a directed volcanic blast (7) olivine-rich komatiitic lavas on central volcanoes and (8) magmatic inflation/deflation on <span class="hlt">caldera</span> flanks localizing craterlets and extinct fumaroles in "loop" patterns. Regarding (6), directed volcanic blasts can remove a segment of the volcano wall as evidenced in terrestrial analogs at Mt. St. Helens and Bezymianny. Impact mechanisms to produce this feature in Copernicus are contrived. For (7) Clementine spectral data show a high olivine content of the central mountains on Copernicus which I interpret as forsteritic spinifex mineralization in komatiitic lavas and not as impact rebound of olivine-rich deep seated rocks. (8) MacDonald (1956) documented loop patterns on the flank of Halemaumau in Hawaii defining arcuate fractures localizing fumaroles and craterlets. Inflation/deflation of subjacent magma bodies are interpreted as the cause for these loops. Inflation/deflation mechanisms on <span class="hlt">caldera</span> flanks are common around terrestrial <span class="hlt">calderas</span>. "Loop" patterns on the flank of Copernicus localizing "gouge" craterlets have been interpreted as ballistic features resulting from the meteorite impact of this crater. Questioned is the logic of a linear N26E trending array of fragments within Copernicus to serve as a source of ballistic projectiles to form the loops localizing conjugate craterlets. The fused craterlet axes on the lunar loops do not point back to a presumed impact center in Copernicus. The axes are oriented parallel to a regional northwest (N35-60W) fracture zone. Implications for an endogenic origin of Copernicus would involve</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V34B..05B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V34B..05B"><span>Thermal history of <span class="hlt">caldera</span>-forming magmatic systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bradshaw, R. W.; Kent, A. J.; Cooper, K. M.; Huber, C.</p> <p>2015-12-01</p> <p>Large, <span class="hlt">caldera</span>-forming silicic eruptions require the assembly and storage of a large volume of magma, and are though to result from either (1) rare high magma flux events needed to maintain melt-rich (eruptible) magma for extended timescales, or (2) magma accumulation at lower magma fluxes, storage for extended timescales as low temperature crystal mushes and rapid rejuvenation prior to eruption. The thermal history of these magmas prior to eruption thus provides an important clue into the processes that lead to eruption, but has been difficult to quantify. However in-situ measurement of Sr and other trace elements in plagioclase, coupled with diffusion models, can be used to constrain the time magmas spend at different temperatures. Progressive differentiation of plagioclase from a silicic magma produces plagioclase with lower Sr at low An—producing a positive correlation between Sr and An, which is the opposite of what is predicted by equilibrium partitioning. Forward modeling of the temperature-dependent diffusion of Sr from this initial disequilibrium condition toward equilibrium concentrations, based on partitioning relationships of An and Sr, gives an estimate of the time individual crystals spend at specific temperatures. Preliminary high spatial resolution LA-ICP-MS analysis of Sr in plagioclase from five <span class="hlt">caldera</span>-forming eruptions show overall positive correlations of Sr and An, suggesting that little diffusive re-equilibration has occurred. Thus, over the lifetime that these magmas reside in the upper crust (>10 k.y.) they likely spend less than a few thousand years at temperatures above 750 °C (the approximate temperature of rheological lockup). These results suggest that the magmas that feed many large <span class="hlt">caldera</span>-forming eruptions are kept in cold storage for long timescales, and that rapid rejuvenation of mush occurs without extended thermal conditioning prior to eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V43B3129B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V43B3129B"><span>Magnetotelluric Investigation of Melt Storage Beneath Okmok <span class="hlt">Caldera</span>, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bennington, N. L.; Bedrosian, P.; Key, K.; Zelenak, G.</p> <p>2015-12-01</p> <p>Alaska accounts for nearly 99% of the seismic moment release within the US. Much of this is associated with the Aleutian volcanic arc, the most tectonically active region in North America, and an ideal location for studying arc magmatism. Okmok is an active volcano located in the central Aleutian arc, defined by a pair of nested, 10 km diameter <span class="hlt">calderas</span>. The subdued topography of Okmok, relative to other Aleutian volcanoes, improves access and permits dense sampling within the <span class="hlt">caldera</span> closer to the underlying magmatic system. Okmok volcano was selected as the site of study for this project due to frequent volcanic activity and the presence of a crustal magma reservoir as inferred from previous coarse resolution seismic studies. In June-July 2015, we carried out an amphibious geophysical field deployment at Okmok. Onshore work in and around the volcano included collection of an array of magnetotelluric (MT) stations and installation of a temporary, year-long seismic array. A ring of 3D offshore MT deployments made around the island augments the onshore array. An additional 2D tectonic-scale profile spans the trench, volcanic arc, and backarc. This new geophysical data will be used to gain a greater understanding of Aleutian arc melt generation, migration, and storage beneath an active <span class="hlt">caldera</span>. We present results from the analysis of the newly collected amphibious 3D MT data. This data will be used to model the distribution and migration of melt within Okmok's crustal magma reservoir. Initial processing of the data shows strong MT signal levels, in particular from a geomagnetic storm that occurred from June 21-23, 2015. A companion abstract discussing the 2D tectonic scale MT profile, which constrains the mantle and deep crust beneath Okmok volcano, is discussed by Zelenak et al.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNS31A1662G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNS31A1662G"><span>Aeromagnetic Study of Tke Huichapan <span class="hlt">Caldera</span>; Central Volcanic Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez, T.; Martin, A.; Alfaro, G.; Oyarzabal, E.</p> <p>2013-12-01</p> <p>Analysis of the aeromagnetic anomalies over the central sector of the Mexican Volcanic Belt sheds new light on the structure of the Huichapan <span class="hlt">Caldera</span>. This volcanic center located 100 Km to the north- northwest of Mexico City is approximately 10 km in diameter and related to an ignimbrite sequence. Milan et al, (1993) and. Aguirre-Diaz and Lopez-Martinez (2009) mapped Huichapan area and described the geology and petrology of the erupted products in the region. Aguirre-Diaz and Lopez-Martinez (2009) suggest the idea of two overlapping <span class="hlt">calderas</span> related to an ignimbrite sequence. The analyzed region is a rectangular area, approximately from 20.25 N to 20.42 N and between 99.42 W and 99.6 W. The total field aeromagnetic data was obtained with a Geometrics G-803 proton magnetometer at a flight altitude of 300 m above ground level. For the analysis of the anomalies, the data was further smoothed to construct a 1 km regularly spaced grid. The anomaly map was compared with the surface geology and larger anomalies were correlated with major volcanic features. Since our main interest was in mapping the subsurface intrusive and volcanic bodies, the total field magnetic anomalies were reduced to the pole by using the double integral Fourier method. The reduced to the pole anomaly map results in a simplified pattern of isolated positive and negative anomalies, which show an improved correlation with all major volcanic structures. For the analysis and interpretation of the anomalies, the reduced to the pole anomalies were continued upward at various reference levels. These operations result in smoothing of the anomaly field by the filtering of high frequency anomalies that may be related to shallow sources. Two profiles were selected that cross the major anomalies on the Huichapan <span class="hlt">Caldera</span>. The Talwani algorithm for 2-D polygonal bodies has been used for calculating the theoretical anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.431..287C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.431..287C"><span>How <span class="hlt">caldera</span> collapse shapes the shallow emplacement and transfer of magma in active volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corbi, F.; Rivalta, E.; Pinel, V.; Maccaferri, F.; Bagnardi, M.; Acocella, V.</p> <p>2015-12-01</p> <p><span class="hlt">Calderas</span> are topographic depressions formed by the collapse of a partly drained magma reservoir. At volcanic edifices with <span class="hlt">calderas</span>, eruptive fissures can circumscribe the outer <span class="hlt">caldera</span> rim, be oriented radially and/or align with the regional tectonic stress field. Constraining the mechanisms that govern this spatial arrangement is fundamental to understand the dynamics of shallow magma storage and transport and evaluate volcanic hazard. Here we show with numerical models that the previously unappreciated unloading effect of <span class="hlt">caldera</span> formation may contribute significantly to the stress budget of a volcano. We first test this hypothesis against the ideal case of Fernandina, Galápagos, where previous models only partly explained the peculiar pattern of circumferential and radial eruptive fissures and the geometry of the intrusions determined by inverting the deformation data. We show that by taking into account the decompression due to the <span class="hlt">caldera</span> formation, the modeled edifice stress field is consistent with all the observations. We then develop a general model for the stress state at volcanic edifices with <span class="hlt">calderas</span> based on the competition of <span class="hlt">caldera</span> decompression, magma buoyancy forces and tectonic stresses. These factors control: 1) the shallow accumulation of magma in stacked sills, consistently with observations; 2) the conditions for the development of circumferential and/or radial eruptive fissures, as observed on active volcanoes. This top-down control exerted by changes in the distribution of mass at the surface allows better understanding of how shallow magma is transferred at active <span class="hlt">calderas</span>, contributing to forecasting the location and type of opening fissures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.G31C..03A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.G31C..03A"><span>An overview of recent (1988 to 2014) <span class="hlt">caldera</span> unrest: knowledge and perspectives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Acocella, V.</p> <p>2015-12-01</p> <p><span class="hlt">Calderas</span> are among the most active and dangerous volcanoes. <span class="hlt">Caldera</span> unrest is defined by enhanced seismicity, gravity changes, surface deformation and degassing. Although much <span class="hlt">caldera</span> unrest does not lead to an eruption, every eruption is preceded by an unrest episode. Therefore, the proper description of unrest and the forecast of its possible outcome is a timely and challenging task. Here we review the best known unrest at <span class="hlt">calderas</span> from 1988 to 2014, building on previous work and propose an updated database. Where established, the root cause for unrest is always magmatic; none was purely hydrothermal or tectonic. An interpretive classification of unrest invokes two spectra - compositional (mafic to felsic) and the state of magma conduits feeding from the magma reservoir(s) to the surface (from fully plugged, through semi-plugged, to open). Magma and gas in open conduits can rise and erupt freely; magma in semi-plugged conduits erupts less frequently, yet still allows some gas to escape; plugged conduits allow neither magma nor gas to escape. Unrest in mafic <span class="hlt">calderas</span> is subtler, less pronounced and repeated, especially with open systems, ensuring the continuous, aseismic and moderate release of magma. Plugged felsic <span class="hlt">calderas</span> erupt infrequently, anticipated by isolated, short and seismically active unrest. Semi-plugged felsic <span class="hlt">calderas</span> also erupt infrequently and are restless over decades or centuries, with uplift, seismicity and degassing and, on the longer-term, resurgence, suggesting repeated stalled intrusions. Finally, the expected advances in better understanding <span class="hlt">caldera</span> unrest are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026179','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026179"><span>Deformation of the Aniakchak <span class="hlt">Caldera</span>, Alaska, mapped by InSAR</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kwoun, Oh-Ig; Lu, Zhiming</p> <p>2004-01-01</p> <p>The deformation of Aniakchak volcano is investigated using 19 ERS-1 / 2 interferometric synthetic aperture radar (InSAR) data from 1992 through 2002. InSAR images from the different time intervals reveal that the10-km-wide <span class="hlt">caldera</span> has been subsiding during the time of investigation. The pattern of subsidence does not following the pyroclastic flows from the last eruption of the <span class="hlt">caldera</span> in 1931. The maximum subsidence is near the center of the <span class="hlt">caldera</span>, with a rate of up to 13 mm/yr. Deformation outside the <span class="hlt">caldera</span> is insignificant. Least squares inversion of the multi-temporal deformation maps indicates that the subsidence rate has been relatively constant. Field observations have identified numerous fumaroles inside the <span class="hlt">caldera</span>. In 1973, temperatures of 80??C were measured at a depth of 15 cm in loose volcanic rubble adjacent to the small cinder cone (about 1.5 km northeast of the vent of the 1931 eruption), whereas springs near a <span class="hlt">caldera</span> lake had a temperature of 25??C in July 1993. Therefore, we suggest the observed subsidence at Aniakchak <span class="hlt">caldera</span> is most likely caused by the reduction of pore fluid pressure of a hydrothermal system located a few kilometers beneath the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70187035','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70187035"><span>An ignimbrite <span class="hlt">caldera</span> from the bottom up: Exhumed floor and fill of the resurgent Bonanza <span class="hlt">caldera</span>, Southern Rocky Mountain volcanic field, Colorado</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lipman, Peter W.; Zimmerer, Matthew J.; McIntosh, William C.</p> <p>2015-01-01</p> <p>Among large ignimbrites, the Bonanza Tuff and its source <span class="hlt">caldera</span> in the Southern Rocky Mountain volcanic field display diverse depositional and structural features that provide special insights concerning eruptive processes and <span class="hlt">caldera</span> development. In contrast to the nested loci for successive ignimbrite eruptions at many large multicyclic <span class="hlt">calderas</span> elsewhere, Bonanza <span class="hlt">caldera</span> is an areally isolated structure that formed in response to a single ignimbrite eruption. The adjacent Marshall <span class="hlt">caldera</span>, the nonresurgent lava-filled source for the 33.9-Ma Thorn Ranch Tuff, is the immediate precursor for Bonanza, but projected structural boundaries of two <span class="hlt">calderas</span> are largely or entirely separate even though the western topographic rim of Bonanza impinges on the older <span class="hlt">caldera</span>. Bonanza, source of a compositionally complex regional ignimbrite sheet erupted at 33.12 ± 0.03 Ma, is a much larger <span class="hlt">caldera</span> system than previously recognized. It is a subequant structure ∼20 km in diameter that subsided at least 3.5 km during explosive eruption of ∼1000 km3 of magma, then resurgently domed its floor a similar distance vertically. Among its features: (1) varied exposure levels of an intact <span class="hlt">caldera</span> due to rugged present-day topography—from Paleozoic and Precambrian basement rocks that are intruded by resurgent plutons, upward through precaldera volcanic floor, to a single thickly ponded intracaldera ignimbrite (Bonanza Tuff), interleaved landslide breccia, and overlying postcollapse lavas; (2) large compositional gradients in the Bonanza ignimbrite (silicic andesite to rhyolite ignimbrite; 60%–76% SiO2); (3) multiple alternations of mafic and silicic zones within a single ignimbrite, rather than simple upward gradation to more mafic compositions; (4) compositional contrasts between outflow sectors of the ignimbrite (mainly crystal-poor rhyolite to east, crystal-rich dacite to west); (5) similarly large compositional diversity among postcollapse <span class="hlt">caldera</span>-fill lavas and resurgent</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013362','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013362"><span>The Loma Seca tuff and the Calabozos <span class="hlt">caldera</span>: a major ash-flow and <span class="hlt">caldera</span> complex in the southern Andes of central Chile.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hildreth, W.; Grunder, A.L.; Drake, Robert E.</p> <p>1984-01-01</p> <p>A composite ring-structure <span class="hlt">caldera</span> of Late Pleistocene age, 26 X 14km in size, has been discovered and mapped near the Andean crest in central Chile (35o 30'S). Rhyolitic to dacitic zoned ashflow sheets, each representing 150-300 km3 of magma, were erupted 0.8, 0.3 and 0.15 m.y. ago; the youngest of the associated collapses was closely followed by resurgent doming of the <span class="hlt">caldera</span> floor and the development of a longitudinal graben. Post-<span class="hlt">caldera</span> eruption of dacite and andesite have persisted into Holocene time and active hot springs are abundant along <span class="hlt">caldera</span>-marginal and resurgent fault systems, suggesting a significant geothermal energy resource. The ash-flow magmatism has been no less important in this segment of the glaciated S Andes than in the arid central Andes and may well be accounted for by the existence of thicker crust in both regions.- L.H.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022809','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022809"><span>Dilational processes accompanying earthquakes in the Long Valley <span class="hlt">Caldera</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dreger, Douglas S.; Tkalcic, Hrvoje; Johnston, M.</p> <p>2000-01-01</p> <p>Regional distance seismic moment tensor determinations and broadband waveforms of moment magnitude 4.6 to 4.9 earthquakes from a November 1997 Long Valley <span class="hlt">Caldera</span> swarm, during an inflation episode, display evidence of anomalous seismic radiation characterized by non-double couple (NDC) moment tensors with significant volumetric components. Observed coseismic dilation suggests that hydrothermal or magmatic processes are directly triggering some of the seismicity in the region. Similarity in the NDC solutions implies a common source process, and the anomalous events may have been triggered by net fault-normal stress reduction due to high-pressure fluid injection or pressurization of fluid-saturated faults due to magmatic heating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V44A..03J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V44A..03J"><span>Analogue of <span class="hlt">Caldera</span> Dynamics: the Controlled Salt Cavern Collapse</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jousset, P. G.; Rohmer, J.</p> <p>2012-12-01</p> <p><span class="hlt">Caldera</span> collapse (or pit-crater) dynamics are inferred from geological observations and laboratory experiments. Here, we present an analogue of <span class="hlt">caldera</span> collapse at field scale and possible analogy with large scale <span class="hlt">caldera</span> dynamics. Through an original exploitation technique in sedimentary environment, a salt layer is emptied, leaving a brine-filled cavern, which eventually collapses after overburden falls into the cavern. Such a collapse was monitored in East France by many instruments (including GPS, extensometers, geophones, broadband seismological sensors, tiltmeter, gravity meter, … ), which allowed us to describe mechanisms of the collapse. Micro-seismicity is a good indicator of spatio-temporal evolution of physical properties of rocks prior to catastrophic events like volcanic eruptions or landslides and may be triggered by a number of causes including dynamic characteristics of processes in play or/and external forces. We show evidence of triggered micro-seismicity observed in the vicinity of this underground salt cavern prone to collapse by a remote M~7.2 earthquake, which occurred ~12000 kilometres away. High-dynamic broadband records reveal the strong time-correlation between a dramatic change in the rate of local high-frequency micro-seismicity and the passage of low-frequency seismic waves, including body, Love and Rayleigh surface waves. Pressure was lowered in the cavern by pumping operations of brine out of the cavern. We demonstrate the near critical state of the cavern before the collapse by means of 2D axisymmetric elastic finite-element simulations. Stress oscillations due to the seismic waves may have exceeded the strength required for the rupture of the complex media made of brine and rock triggering micro-earthquakes and leading to damage of the overburden and eventually collapse of the salt cavern. The increment of stress necessary for the failure of a Dolomite layer is of the same order or magnitude as the maximum dynamic stress magnitude</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015922','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015922"><span>Magmatic unrest at Long Valley <span class="hlt">Caldera</span>, California, 1980-1990</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bailey, R.A.; Hill, D.P.</p> <p>1990-01-01</p> <p>On May 25, 1980, the resort town of Mammoth Lakes, California, was shaken by a remarkable 48-hour-long earthquake sequence that included four M=6, two M=5 and 300 M=3 quakes. The nature of the precursory seismicity plus the unusual character of the May 25-27 sequence itself suggested that it was not typical of tectonic earthquakes in the region. Discovery of 25 cm of domical uplift centred on the resurgent dome within Long Valley <span class="hlt">caldera</span> strongly implied that this activity was accompanied, if not caused, by influex of magma into the Long Valley magma chamber. -Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMGP53A0777G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMGP53A0777G"><span>Aeromagnetic Study of the Amealco <span class="hlt">Caldera</span>, Central Mexican Volcanic Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gonzalez, T.; Salas, J.; Yamamoto, J.</p> <p>2008-12-01</p> <p>Analysis of the aeromagnetic anomalies over the central sector of the Mexican Volcanic Belt sheds new light on the structure of Amealco <span class="hlt">Caldera</span>. This volcanic center located NW of Mexico City is approximately 10 km in diameter,is partially cut by a regional fault (Epitafio Huerta fault). Aguirre-Diaz (1993, 1996) has mapping the Amealco area and described the geology and petrology of the erupted products. This <span class="hlt">Caldera</span> was formed by a large eruption which produced an ignimbrite which covers the area. The Amealco tuff is the most important volcanic unit because of its volume and distribution. After the emplacement of the central lava dome, volcanism persisted for more than a million years in the periphery and in the <span class="hlt">Caldera</span> rim. This activity forms the Garabato dome and the Comal Scoria cone. The analyzed region is a rectangular area, approximately from 20o N to 20o 15´ N and between 100o W and 100o 20' W. The total field aeromagnetic data was obtained with a Geometrics G-803 proton magnetometer at a flight altitude of 300 m above ground level. For the analysis of the anomalies, the data was further smoothed to construct a 2 km regularly spaced grid. The anomaly map was compared with the surface geology and larger anomalies were correlated with major volcanic features. Since our main interest was in mapping the subsurface intrusive and volcanic bodies, the total field magnetic anomalies were reduced to the pole by using the double integral Fourier method. The reduced to the pole anomaly map results in a simplified pattern of isolated positive and negative anomalies, which show an improved correlation with all major volcanic structures. For the analysis and interpretation of the anomalies, the reduced to the pole anomalies were continued upward at various reference levels. These operations result in smoothing of the anomaly field by the filtering of high frequency anomalies that may be related to shallow sources. Two profiles were selected that cross the major</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27237112','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27237112"><span>Campylobacter in broiler slaughter samples assessed by direct count on mCCDA and <span class="hlt">Campy</span>-Cefex agar.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gonsalves, Camila Cristina; Borsoi, Anderlise; Perdoncini, Gustavo; Rodrigues, Laura Beatriz; do Nascimento, Vladimir Pinheiro</p> <p>2016-01-01</p> <p>Campylobacter spp. cause foodborne illnesses in humans primarily through the consumption of contaminated chicken. The aim of this study was to evaluate the United States Department of Agriculture's (USDA) recommended methodology, protocol MLG 41.02, for the isolation, identification and direct plate counting of Campylobacter jejuni and C. coli samples from the broiler slaughtering process. A plating method using both mCCDA and <span class="hlt">Campy</span>-Cefex agars is recommended to recover Campylobacter cells. It is also possible to use this method in different matrices (cloacal swabs and water samples). Cloacal swabs, samples from pre-chiller and post-chiller carcasses and samples of pre-chiller, chiller and direct supply water were collected each week for four weeks from the same flock at a slaughterhouse located in an abattoir in southern Brazil. Samples were analyzed to directly count Campylobacter spp., and the results showed a high frequency of Campylobacter spp. on <span class="hlt">Campy</span>-Cefex agar. For the isolated species, 72% were identified as Campylobacter jejuni and 38% as Campylobacter coli. It was possible to count Campylobacter jejuni and Campylobacter coli from different samples, including the water supply samples, using the two-agar method. These results suggest that slaughterhouses can use direct counting methods with both agars and different matrices as a monitoring tool to assess the presence of Campylobacter bacteria in their products. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7149R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7149R"><span>Post-<span class="hlt">caldera</span> faulting of the Late Quaternary Menengai <span class="hlt">caldera</span>, Central Kenya Rift (0.20°S, 36.07°E)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riedl, Simon; Melnick, Daniel; Mibei, Geoffrey K.; Njue, Lucy; Strecker, Manfred R.</p> <p>2015-04-01</p> <p>A structural geological analysis of young <span class="hlt">caldera</span> volcanoes is necessary to characterize their volcanic activity, assess their geothermal potential, and decipher the spatio-temporal relationships of faults on a larger tectonic scale. Menengai <span class="hlt">caldera</span> is one of several major Quaternary trachytic <span class="hlt">caldera</span> volcanoes that are aligned along the volcano-tectonic axis of the Kenya Rift, the archetypal active magmatic rift and nascent plate boundary between the Nubia and Somalia plates. The <span class="hlt">caldera</span> covers an area of approximately 80 km² and is among the youngest and also largest <span class="hlt">calderas</span> in the East African Rift, situated close to Nakuru - a densely populated urban area. There is an increasing interest in <span class="hlt">caldera</span> volcanoes in the Kenya Rift, because these are sites of relatively young volcanic and tectonic activity, and they are considered important sites for geothermal exploration and future use for the generation of geothermal power. Previous studies of Menengai showed that the <span class="hlt">caldera</span> collapsed in a multi-event, multiple-block style, possibly as early as 29 ka. In an attempt to characterize the youngest tectonic activity along the volcano-tectonic axis in the transition between the Central and Northern Kenya rifts we first used a high-resolution digital surface model, which we derived by structure-from-motion from an unmanned aerial vehicle campaign. This enabled us to identify previously unrecognized normal faults, associated dyke intrusions and volcanic eruptive centers, and transfer faults with strike-slip kinematics in the <span class="hlt">caldera</span> interior and its vicinity. In a second step we verified these structures at outcrop scale, assessed their relationship with known stratigraphic horizons and dated units, and performed detailed fault measurements, which we subsequently used for fault-kinematic analysis. The most important structures that we mapped are a series of north-northeast striking normal faults, which cross-cut both the <span class="hlt">caldera</span> walls and early Holocene lake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....2580G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....2580G"><span>Structural controls on diffuse degassing in the Las Cañadas <span class="hlt">caldera</span>, Tenerife, Canary Islands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galindo, I.; Soriano, C.; Martí, J.; Pérez, N.</p> <p>2003-04-01</p> <p>The Las Cañadas <span class="hlt">caldera</span> is an elliptical depression located in the central part of the Tenerife Island. The active Teide stratovolcano stands in the centre of the depression, which is limited to the south by the <span class="hlt">caldera</span> wall, up to 500 m high above the <span class="hlt">caldera</span> floor. Mapping most of the <span class="hlt">caldera</span> wall at 1:5000 has provided new insights on its stratigraphy, structure, and geological evolution. Three major ENE-WSW normal faults have been mapped on the <span class="hlt">caldera</span> wall in the area comprised between El Llano de Ucanca and Los Azulejos, where an intense hydrothermal alteration affects the lower stratigraphic levels of the <span class="hlt">caldera</span> wall. Hydrothermal alteration is rather distinctive in this area, showing bluish to greenish colours. Most of the phonolitic cone sheets and radial dykes of the <span class="hlt">caldera</span> wall do not show distinctive hydrothermal features, as do show the phonolitic pyroclastic rocks and lavas of the lower parts of the <span class="hlt">caldera</span> wall. This suggests the main episodes of dyke intrusion in the Las Cañadas <span class="hlt">caldera</span> postdate hydrothermal alteration. ENE-WSW normal faults involve dyke swarms and rocks of the upper stratigraphic levels of the <span class="hlt">caldera</span> wall, and show displacements of up to 100 m. Unfortunately the upper possible age of these faults is poorly constrained since no contact relationship has been observed between fault planes and the rocks of the uppermost stratigraphic levels of the <span class="hlt">caldera</span> wall. The rocks of the <span class="hlt">caldera</span> wall adjacent to the faults are intensely fractured at the macro and mesoscale. In addition to field mapping, a soil gas survey was carried out at the <span class="hlt">caldera</span> depression. Soil CO2 efflux and H2 concentration were measured reaching values of 12 gm-2d-1 and 4 ppmV, respectively. Spatial distribution of these species showed that positive anomalies coincide with the surface expression of the three major faults and their adjacent intensely fractured zone. The high CO2 and H2 values and their coincidence with major normal faults suggests that degassing in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27980204','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27980204"><span>Seismic constraints on <span class="hlt">caldera</span> dynamics from the 2015 Axial Seamount eruption.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilcock, William S D; Tolstoy, Maya; Waldhauser, Felix; Garcia, Charles; Tan, Yen Joe; Bohnenstiehl, DelWayne R; Caplan-Auerbach, Jacqueline; Dziak, Robert P; Arnulf, Adrien F; Mann, M Everett</p> <p>2016-12-16</p> <p>Seismic observations in volcanically active <span class="hlt">calderas</span> are challenging. A new cabled observatory atop Axial Seamount on the Juan de Fuca ridge allows unprecedented real-time monitoring of a submarine <span class="hlt">caldera</span>. Beginning on 24 April 2015, the seismic network captured an eruption that culminated in explosive acoustic signals where lava erupted on the seafloor. Extensive seismic activity preceding the eruption shows that inflation is accommodated by the reactivation of an outward-dipping <span class="hlt">caldera</span> ring fault, with strong tidal triggering indicating a critically stressed system. The ring fault accommodated deflation during the eruption and provided a pathway for a dike that propagated south and north beneath the <span class="hlt">caldera</span>'s east wall. Once north of the <span class="hlt">caldera</span>, the eruption stepped westward, and a dike propagated along the extensional north rift. Copyright © 2016, American Association for the Advancement of Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2014/1222/pdf/ofr2014-1222_report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2014/1222/pdf/ofr2014-1222_report.pdf"><span>Long Valley <span class="hlt">Caldera</span> 2003 through 2014: overview of low level unrest in the past decade</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wilkinson, Stuart K.; Hill, David P.; Langbein, John O.; Lisowski, Michael; Mangan, Margaret T.</p> <p>2014-01-01</p> <p>Long Valley <span class="hlt">Caldera</span> is located in California along the eastern escarpment of the Sierra Nevada Range. The <span class="hlt">caldera</span> formed about 760,000 years ago as the eruption of 600 km3 of rhyolite magma (Bishop Tuff) resulted in collapse of the partially evacuated magma chamber. Resurgent doming in the central part of the <span class="hlt">caldera</span> occurred shortly afterwards, and the most recent eruptions inside the <span class="hlt">caldera</span> occurred about 50,000 years ago. The <span class="hlt">caldera</span> remains thermally active, with many hot springs and fumaroles, and has had significant deformation and seismicity since at least 1978. Periods of intense unrest in the 1980s to early 2000s are well documented in the literature (Hill and others, 2002; Ewert and others, 2010). In this poster, we extend the timeline forward, documenting seismicity and deformation over the past decade.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EOSTr..91....1W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EOSTr..91....1W"><span><span class="hlt">Calderas</span> Bottom-to-Top: An Online Seminar and Field Trip</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilcock, Jack; Longpré, Marc-Antoine; de Moor, J. Maarten; Ross, Jake; Zimmerer, Matt</p> <p>2010-01-01</p> <p><span class="hlt">Caldera</span>-related processes have deep implications in Earth science and are important to the general public. To the geologist, <span class="hlt">calderas</span> are surface manifestations of large magma reservoirs and the source of some of the largest eruptions on Earth. For society, these volcanoes represent not only an extreme volcanic hazard but also a potential source of abundant geothermal energy and metal ore deposits. During February-April 2009, an innovative, online course entitled “<span class="hlt">Calderas</span>: Bottom-to-top” was offered across several universities to students interested in investigating <span class="hlt">caldera</span>-forming processes associated with “supervolcanoes.” Supervolcanoes have the ability to spew hundreds to thousands of cubic kilometers of material from large magma chambers pooled in the Earth's crust. A <span class="hlt">caldera</span>-forming eruption results from overpressurization of the chamber and leads to formation of large depressions, tens of kilometers in diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JVGR...59...47G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JVGR...59...47G"><span>Preliminary geologic studies of Sierra El Aguajito (Baja California, Mexico): a resurgent-type <span class="hlt">caldera</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garduño-Monroy, V. H.; Vargas-Ledezma, H.; Campos-Enriquez, J. O.</p> <p>1993-12-01</p> <p>Geologic field studies conducted in the Quaternary volcanic field of Tres Virgenes (State of Baja California Sur, Mexico) revealed the existence of a resurgent <span class="hlt">caldera</span>. The <span class="hlt">caldera</span>'s eruptive products, the Aguajito sequence, overlie the products of the nearby Reforma <span class="hlt">caldera</span> (Reforma sequence) whose youngest products have already been dated as Quaternary. The rim of the Aguajito <span class="hlt">caldera</span> is inferred by the existence of an arcuate alignment of rhyolitic domes. The mean diameter of this subcircular feature is 10 km. The volume of its mapped acidic products is a minimum of 10 km 3. Several horizons within the sequence contain shells. K/Ar dates of the ignimbrites and domes of El Aguajito formation confirm that the unit are Pleistocene. The detailed stratigraphy also shows the evolution of a marine regression partly related to the <span class="hlt">caldera</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5130305','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5130305"><span>The Twin Peaks <span class="hlt">caldera</span>: A window into the emplacement and evolution of a <span class="hlt">Caldera</span>-filling ignimbrite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jellinek, A.M.; Geist, D. . Dept. of Geology)</p> <p>1993-04-01</p> <p>The Twin Peaks <span class="hlt">caldera</span>, about 13 km west of Challis, Idaho, is an elliptical Valles-sized <span class="hlt">caldera</span> with dimensions of 20 x 14 km. The tuff of Challis Creek (TCR) is largely a <span class="hlt">caldera</span>-fill ignimbrite sequence that was emplaced about 45 Ma during the last stages of the Eocene Challis volcanic episode. Post-volcanic block faulting and erosion have deeply-dissected the TCR section resulting in over 1,200 meters of vertical exposure. This feature has provided a rare opportunity to both describe intracaldera-fill cooling facies and explore the pre-, syn-, and post-emplacement mechanisms controlling their development. Hardyman (1983) delineated two major intracaldera cooling units on the basis of rock texture, degree of welding, crystallinity, and pumice color relative to the matrix. In this study these two cooling units have been expanded to include one simple cooling unit, T0 (at least 140 m thick), and two compound units, T1 (140--670 m thick) and T2 (at least 800 m thick), with three and eight distinct facies respectively. The cooling units and their associated facies are defined on the basis of field observations of: (1) macroscopic textures and degree of welding, (2) weathering color, (3) matrix color, crystallinity, and lithic content, and, (4) pumice crystallinity, flattening, and color relative to the matrix. Petrographic observations of: (1) mineral assemblages and styles of phenocryst fragmentation, (2) alignment of glass shards and their relative, compaction and contortion around phenocrysts, and (3) the extent of compaction and contortion and crystallinity of collapsed pumice structures have further refined facies determinations. A preliminary model for the T2 compound cooling unit suggests that the development of the eight T2 facies can be explained by post-emplacement collapse of pore space combined with the exsolution of volatiles followed by further compaction and welding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5940237','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5940237"><span>Intracaldera volcanic activity, Toledo <span class="hlt">caldera</span> and embayment, Jemez Mountains, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heiken, G.; Goff, F.; Stix, J.; Shafiqullah, M.; Garcia, S.; Hagan, R.</p> <p>1986-02-10</p> <p>The Toledo <span class="hlt">caldera</span> was formed at 1.47 +- 0.06 Ma during the catastrophic eruption of the lower member, Bandelier Tuff. The <span class="hlt">caldera</span> was obscured at 1.12 +- 0.03 Ma during eruption of the equally voluminous upper member of the Bandelier Tuff that led to formation of the Valles <span class="hlt">caldera</span>. Earlier workers interpreted a 9-km-diameter embayment, located NE of the Valles <span class="hlt">caldera</span> (Toledo embayment), to be a remnant of the Toledo <span class="hlt">caldera</span>. Drill hole data and new K-Ar dates of Toledo intracaldera domes redefine the position of Toledo <span class="hlt">caldera</span>, nearly coincident with and of the same dimensions as the younger Valles <span class="hlt">caldera</span>. the Toledo embayment may be of tectonic origin or a small Tschicoma volcanic center <span class="hlt">caldera</span>. This interpretation is consistent with distribution of the lower member of the Bandelier Tuff and with several other field and drilling-related observations. Explosive activity associated with Cerro Toledo Rhyolite domes is recorded in tuff deposits located between the lower and upper members of the Bandelier Tuff on the northeast flank of the Jemez Mountains. Recorded in the tuff deposits are seven cycles of explosive activity. Most cycles consists of phreatomagmatic tuffs that grade upward into Plinian pumice beds. A separate deposit, of the same age and consisting of pyroclastic surges and flows, is associated with Rabbit Mountain, located on the southeast rim of the Valles-Toledo <span class="hlt">caldera</span> complex. These are the surface expression of what may be a thicker, more voluminous intracaldera tuff sequence. The combined deposits of the lower and upper members of the Bandelier Tuff, Toledo and Valles intracaldera sediments, tuffs, and dome lavas form what we interpret to be a wedge-shaped <span class="hlt">caldera</span> fill. This sequence is confirmed by deep drill holes and gravity surveys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817005T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817005T"><span>A multidisciplinary study of the 2014-2015 Bárðarbunga <span class="hlt">caldera</span> collapse, Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tumi Gudmundsson, Magnus; Jonsdóttir, Kristin; Hooper, Andy; Holohan, Eoghan; Halldorsson, Saemundur</p> <p>2016-04-01</p> <p>The collapse of the ice-filled Bárðarbunga <span class="hlt">caldera</span> in central Iceland occurred in autumn and winter, when weather was highly unsettled and conditions for monitoring in many ways difficult. Nevertheless several detailed time series could be obtained on the collapse and to a degree the associated flood-basalt eruption in Holuhraun. This was achieved through applying an array of sensors, that were ground, air and satellite based, partly made possible through the EU-funded FUTUREVOLC supersite project. This slow <span class="hlt">caldera</span> collapse lasted six months, ending in February 2015. The array of sensors used, coupled with the long duration of the event, allowed unprecedented detail in observing a <span class="hlt">caldera</span> collapse. The deciphering of the course of events required the use of aircraft altimeter surveys of the ice surface, seismic and GPS monitoring, the installation of a GPS station on the glacier surface in the centre of the <span class="hlt">caldera</span> that continuously recorded the subsidence. Full Stokes 3-D modelling of the 700-800 m thick ice in the <span class="hlt">caldera</span>, constrained by observations, was applied to remove the component of ice deformation that had a minor effect on the measured subsidence. The maximum subsidence of the subglacial <span class="hlt">caldera</span> floor was about 65 meters. The combined interpretation of geochemical geobarometers, subsidence geometry with GPS and InSAR deformation signals, seismicity and distinct element deformation modelling of the subsidence provided unprecedented detail of the process and mechanism of <span class="hlt">caldera</span> collapse. The collapse involved the re-activation of pre-existing ring faults, and was initiated a few days after magma started to drain from underneath the <span class="hlt">caldera</span> towards the eventual eruption site in Holuhraun, 45 km to the northeast. The <span class="hlt">caldera</span> collapse was slow and gradual, and the flow rate from underneath the <span class="hlt">caldera</span> correlates well with the lava flow rate in Holuhraun, both in terms of total volume and variations in time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..659B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..659B"><span>A tectonic model of the Askja <span class="hlt">caldera</span> system based on FEM analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Browning, John; Gudmundsson, Agust; Thordarson, Thorvaldur</p> <p>2015-04-01</p> <p>The Askja volcanic system lies on the boundary between the Eurasian and North American tectonic plates and is an example of a multiple <span class="hlt">caldera</span> formed in an extensional regime. Askja is composed of at least three <span class="hlt">calderas</span>, the last of which formed during an explosive eruption in A.D. 1875. The <span class="hlt">caldera</span> floor has been subsiding almost continuously since 1983; total subsidence in this period is around 1.1 metres. Perhaps surprisingly, there has been no slip or movement on the <span class="hlt">caldera</span> bounding ring-faults during this subsidence period. Various models have been proposed to explain this unusual signal. Previous models suggest two magma sources, one shallow at around 3 km depth and one much larger at around 16 km depth. In this model, subsidence is caused by depressurisation in both sources as a result of cooling contraction and crystallisation. In other models subsidence results from magma being squeezed out of the shallow chamber laterally; or somehow draining back into a deep seated reservoir. In this study we examine the contribution of regional extension and structural discontinuities to the current subsidence of Askja <span class="hlt">caldera</span>. Using a finite element numerical analysis, we ascertain the state of stresses at Askja <span class="hlt">caldera</span> over time based on several different magma body geometries. We calculate surface displacements expected from extension around a shallow magma body, and place these findings in the context of Icelandic <span class="hlt">calderas</span>. In addition we investigate the likely stress effects of the Askja <span class="hlt">caldera</span> on the associated part of the Northern Volcanic Zone. The proposed model seeks to understand the volcano-tectonic conditions at Askja during <span class="hlt">caldera</span> formation, as well as during rifting episodes. The models presented will be useful in assessing likely future rifting events and fissure swarm activity in Askja <span class="hlt">caldera</span>, and neighbouring volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..174..269U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..174..269U"><span>Structure of the Nemrut <span class="hlt">caldera</span> (Eastern Anatolia, Turkey) and associated hydrothermal fluid circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ulusoy, İnan; Labazuy, Philippe; Aydar, Erkan; Ersoy, Orkun; Çubukçu, Evren</p> <p>2008-07-01</p> <p>Plio-Quaternary volcanism played an important role in the present physical state of Eastern Anatolia. Mount Nemrut, situated to the west of Lake Van is one of the main volcanic centers in the region, with a spectacular summit <span class="hlt">caldera</span> 8.5 × 7 km in diameter. The most recent eruptions of the volcano were in 1441, 1597 and 1692. Nemrut Lake covers the western half of the <span class="hlt">caldera</span>; it is a deep, half-bowl-shaped lake with a maximum depth of 176 m. Numerous eruption centers are exposed within the <span class="hlt">caldera</span> as a consequence of magma-water interaction. Current activity of Nemrut <span class="hlt">caldera</span> is revealed as hot springs, fumaroles and a small, hot lake. Self-potential and bathymetric surveys carried out in the <span class="hlt">caldera</span> were used to characterize the structure of the <span class="hlt">caldera</span> and the associated hydrothermal fluid circulation. In addition, analyses based on digital elevation models and satellite imagery were used to improve our knowledge about the structure of the <span class="hlt">caldera</span>. According to SP results, the flanks of the volcano represent "the hydrogeologic zone", whereas the intra-<span class="hlt">caldera</span> region is an "active hydrothermal area" where the fluid circulation is controlled by structural discontinuities. There is also a northern fissure zone which exhibits hydrothermal signatures. Nemrut <span class="hlt">caldera</span> collapsed piecemeal, with three main blocks. Stress controlling the collapse mechanism seems to be highly affected by the regional neotectonic regime. In addition to the historical activity, current hydrothermal and hydrogeologic conditions in the <span class="hlt">caldera</span>, in which there is a large lake and shallow water table, increase the risk of the quiescent volcano.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70160102','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70160102"><span>Renewed inflation of Long Valley <span class="hlt">Caldera</span>, California (2011 to 2014)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Montgomery-Brown, Emily; Wicks, Chuck; Cervelli, Peter F.; Langbein, John O.; Svarc, Jerry L.; Shelly, David R.; Hill, David P.; Lisowski, Michael</p> <p>2015-01-01</p> <p>Slow inflation began at Long Valley <span class="hlt">Caldera</span> in late 2011, coinciding with renewed swarm seismicity. Ongoing deformation is concentrated within the <span class="hlt">caldera</span>. We analyze this deformation using a combination of GPS and InSAR (TerraSAR-X) data processed with a persistent scatterer technique. The extension rate of the dome-crossing baseline during this episode (CA99 to KRAC) is 1 cm/yr, similar to past inflation episodes (1990–1995 and 2002–2003), and about a tenth of the peak rate observed during the 1997 unrest. The current deformation is well modeled by the inflation of a prolate spheroidal magma reservoir ∼7 km beneath the resurgent dome, with a volume change of ∼6 × 106 m3/yr from 2011.7 through the end of 2014. The current data cannot resolve a second source, which was required to model the 1997 episode. This source appears to be in the same region as previous inflation episodes, suggesting a persistent reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025513','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025513"><span>Summary of recent research in Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sorey, M.L.; McConnell, V.S.; Roeloffs, E.</p> <p>2003-01-01</p> <p>Since 1978, volcanic unrest in the form of earthquakes and ground deformation has persisted in the Long Valley <span class="hlt">caldera</span> and adjacent parts of the Sierra Nevada. The papers in this special volume focus on periods of accelerated seismicity and deformation in 1980, 1983, 1989-1990, and 1997-1998 to delineate relations between geologic, tectonic, and hydrologic processes. The results distinguish between earthquake sequences that result from relaxation of existing stress accumulation through brittle failure and those in which brittle failure is driven by active intrusion. They also indicate that in addition to a relatively shallow (7-10-km) source beneath the resurgent dome, there exists a deeper (???15-km) source beneath the south moat. Analysis of microgravimety and deformation data indicates that the composition of the shallower source may involve a combination of silicic magma and hydrothermal fluid. Pressure and temperature fluctuations in wells have accompanied periods of crustal unrest, and additional pressure and temperature changes accompanying ongoing geothermal power production have resulted in land subsidence. The completion in 1998 of a 3000-m-deep drill hole on the resurgent dome has provided useful information on present and past periods of circulation of water at temperatures of 100-200??C within the crystalline basement rocks that underlie the post-<span class="hlt">caldera</span> volcanics. The well is now being converted to a permanent geophysical monitoring station. ?? 2003 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5127204','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5127204"><span>Origin of Hot Creek Canyon, Long Valley <span class="hlt">caldera</span>, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maloney, N.J. . Dept. of Geological Sciences)</p> <p>1993-04-01</p> <p>Hot Creek has eroded a canyon some thirty meters deep across the Hot Creek rhyolite flows located in the southeastern moat of Long Valley <span class="hlt">Caldera</span>. Maloney (1987) showed that the canyon formed by headward erosion resulting from spring sapping along hydrothermally altered fractures in the rhyolite, and the capture of Mammoth Creek. This analysis ignored the continuing uplift of the central resurgent dome. Reid (1992) concluded that the downward erosion of the canyon must have kept pace with the uplift. Long Valley Lake occupied the <span class="hlt">caldera</span> until 100,000 to 50,000 years before present. The elevation of the shoreline, determined by trigonometric leveling, is 2,166 m where the creek enters the canyon and 2,148 m on the downstream side of the rhyolite. The slope of the strand line is about equal to the stream gradient. The hill was lower and the stream gradient less at the time of stream capture. Rotational uplift increased the stream gradient which increased the rate of downward erosion and formed the V-shaped canyon</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70155954','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70155954"><span>Months between rejuvenation and volcanic eruption at Yellowstone <span class="hlt">caldera</span>, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W</p> <p>2015-01-01</p> <p>Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at <span class="hlt">calderas</span> with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare <span class="hlt">caldera</span>-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6644089','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6644089"><span>Highly evolved rhyolitic glass compositions from the Toba <span class="hlt">Caldera</span>, Sumatra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chesner, C.A.</p> <p>1985-01-01</p> <p>The quartz latite to rhyolitic ash flow tuffs erupted form the Toba <span class="hlt">Caldera</span>, perhaps the largest <span class="hlt">caldera</span> on earth (100 by 30 kms), provide the unique opportunity to study a highly differentiated liquid in equilibrium with numerous mineral phases. Not only are the rocks very crystal rich (30-50%), but at present a minimum of 15 co-existing mineral phases have been identified. Both whole-rock and glass analyses were made by XRF techniques providing data on both major and trace elements. Whole rock chemistry of individual pumices from the youngest eruption at Toba (75,000 years ago), are suggestive of the eruption of two magma compositions across a boundary layer in the magma chamber. Glass chemistry of the pumices also show two distinct liquid compositions. The more silicic pumices, which have the most evolved glass compositions, are similar to the whole rock chemistry of the few aplitic pumices and cognate granitic xenoliths that were collected. This highly evolved composition resulted from the removal of up to 15 mineral phases and may be a fractionation buffered, univariant composition. The glasses from the less silicic pumices are similar to the whole rock chemistry of the more silicic pumice, thus falling nicely on a fractionation trend towards the univariant composition for these rocks. This set of glass compositions allows an independent test for the origin of distal ashes thought to have erupted from Toba and deposited in Malaysia, the Indian Ocean, and as far away as India.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6355890','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6355890"><span>Radon in groundwater of the Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Flexser, S.; Wollenberg, H.A.; Smith, A.R.</p> <p>1987-04-01</p> <p>In the Long Valley <span class="hlt">caldera</span>, an area of recently (approx.550 y) active volcanism and current seismic activity, /sup 222/Rn concentrations in hot, warm, and cold spring waters have been measured since 1982. Rn contents of the waters correlate inversely with temperature and specific conductance, with high concentrations (1500 to 2500 pCi/l) occurring in dilute cold springs on the margins of the <span class="hlt">caldera</span>, and low concentrations (12 to 25 pCi/l) in hot to boiling springs. Rn correlates only slightly with the uranium contents of the wide range of rocks which host the hydrological system feeding the springs. These environmental effects on the radon record may mask responses to small or distant seismic, volcanic, or crustal deformation events. To date, anomalous changes in water-borne Rn have been observed in connection with at least one earthquake, which occurred close to the monitoring site. This continuing study points out that an understanding of the geological setting, its associated hydrological system, and environmental influences is necessary to properly evaluate concentrations and changes in groundwater radioactivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/1044a/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1044a/report.pdf"><span>The hydrothermal system of Long Valley <span class="hlt">Caldera</span>, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sorey, M.L.; Lewis, Robert Edward; Olmsted, F.H.</p> <p>1978-01-01</p> <p>Long Valley <span class="hlt">caldera</span>, an elliptical depression covering 450 km 2 on the eastern front of the Sierra Nevada in east-central California, contains a hot-water convection system with numerous hot springs and measured and estimated aquifer temperatures at depths of 180?C to 280?C. In this study we have synthesized the results of previous geologic, geophysical, geochemical, and hydrologic investigations of the Long Valley area to develop a generalized conceptual and mathematical model which describes the gross features of heat and fluid flow in the hydrothermal system. Cenozoic volcanism in the Long Valley region began about 3.2 m.y. (million years) ago and has continued intermittently until the present time. The major event that resulted in the formation of the Long Valley <span class="hlt">caldera</span> took place about 0.7 m.y. ago with the eruption of 600 km 3 or more of Bishop Tuff of Pleistocene age, a rhyolitic ash flow, and subsequent collapse of the roof of the magma chamber along one or more steeply inclined ring fractures. Subsequent intracaldera volcanism and uplift of the west-central part of the <span class="hlt">caldera</span> floor formed a subcircular resurgent dome about 10 km in diameter surrounded by a moat containing rhyolitic, rhyodacitic, and basaltic rocks ranging in age from 0.5 to 0.05 m.y. On the basis of gravity and seismic studies, we estimate an aver- age thickness of fill of 2.4 km above the precaldera granitic and metamorphic basement rocks. A continuous layer of densely welded Bishop Tuff overlies the basement rocks, with an average thickness of 1.4 km; the fill above the welded Bishop Tuff consists of intercalated volcanic flows and tuffs and fluvial and lacustrine deposits. Assuming the average grain density of the fill is between 2.45 and 2.65 g/cm 3 , we calculate the average bulk porosity of the total fill as from 0.11 to 0.21. Comparison of published values of porosity of the welded Bishop Tuff exposed southeast of the <span class="hlt">caldera</span> with calculated values indicates average bulk porosity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916559G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916559G"><span>Sill intrusion in volcanic <span class="hlt">calderas</span>: implications for vent opening probability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giudicepietro, Flora; Macedonio, Giovanni; Martini, Marcello; D'Auria, Luca</p> <p>2017-04-01</p> <p><span class="hlt">Calderas</span> show peculiar behaviors with remarkable dynamic processes, which do not often culminate in eruptions. Observations and studies conducted in recent decades have shown that the most common cause of unrest in the <span class="hlt">calderas</span> is due to magma intrusion; in particular, the intrusion of sills at shallow depths. Monogenic cones, with large areal dispersion, are quite common in the <span class="hlt">calderas</span>, suggesting that the susceptibility analysis based on geological features, is not strictly suitable for estimating the vent opening probability in <span class="hlt">calderas</span>. In general, the opening of a new eruptive vent can be regarded as a rock failure process. The stress field in the rocks that surrounds and tops the magmatic reservoirs plays an important role in causing the rock failure and creating the path that magma can follow towards the surface. In this conceptual framework, we approach the problem of getting clues about the probability of vent opening in volcanic <span class="hlt">calderas</span> through the study of the stress field produced by the intrusion of magma, in particular, by the intrusion of a sill. We simulate the intrusion of a sill free to expand radially, with shape and dimensions which vary with time. The intrusion process is controlled by the elastic response of the rock plate above the sill, which bends because of the intrusion, and by gravity, that drives the magma towards the zones where the thickness of the sill is smaller. We calculated the stress field in the plate rock above the sill. We found that at the bottom of the rock plate above the sill the maximum intensity of tensile stress is concentrated at the front of the sill and spreads radially with it, over time. For this reason, we think that the front of the spreading sill is prone to open for eruptive vents. Even in the central area of the sill the intensity of stress is relatively high, but at the base of the rock plate stress is compressive. Under isothermal conditions, the stress soon reaches its maximum value (time interval</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V13B2832C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V13B2832C"><span>A New Model for Episodic <span class="hlt">Caldera</span> Deformation at Yellowstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cervelli, P. F.; Gervais, S. M.; Lowenstern, J. B.; Wicks, C. W.</p> <p>2012-12-01</p> <p>For nearly 90 years, geodetic measurements at Yellowstone have shown recurring episodes of uplift and subsidence confined mostly to the <span class="hlt">caldera</span> but also extending into the Norris Geyser Basin. The most recent such episode began in late 2004 with the onset of <span class="hlt">caldera</span>-wide uplift that continued for about 5 years before switching to subsidence in late 2009. The physical mechanism driving the deformation is unknown, though several researchers have proposed kinematic models that can reproduce the observed data. The "Lake" earthquake swarm, which occurred in the northern part of Yellowstone Lake from December 2008 through January 2009, provides a new constraint on <span class="hlt">caldera</span> deformation models. The timing of the swarm correlates with an abrupt change in local deformation, which preceded the gradual transition from uplift to subsidence in late 2009. Thus, <span class="hlt">caldera</span> deformation, at least in the vicinity of Yellowstone Lake, consists of two (or more) distinct parts, implying the existence of two (or more) distinct deformation sources. This fresh information leads us to propose a new kinematic model for deformation at Yellowstone, which we develop from the last 15 years of continuous GPS and InSAR data. Our new model consists of three deformation sources: (1) a cauldron block source that is subject to a constant displacement at its base while its surrounding ring fault remains locked; (2) a pressurizing (or depressurizing) spherical cavity near the Norris Geyser Basin, which is known to deform separately from the <span class="hlt">caldera</span>; and (3) a pressurizing (or depressurizing) spherical cavity at the Sour Creek Dome, which we infer from the abrupt change in deformation rate after the Lake Swarm. We use the GPS and InSAR data from the period of strongest signal, summer 2005 through summer 2007, to optimize the geometry of the three sources: the locations and depths of the spherical cavity, and the perimeter of the cauldron block. We then, while holding their geometry fixed, estimate the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5573384','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5573384"><span>History and results of VC-1, the first CSDP corehole in Valles <span class="hlt">caldera</span>, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goff, F.; Rowley, J.; Gardner, J.N.; Hawkins, W.; Goff, S.; Pisto, L.; Polk, G.</p> <p>1985-01-01</p> <p>Valles <span class="hlt">Caldera</span> No. 1 (VC-1) is the first Continental Scientific Drilling Program (CSDP) corehole drilled in the Valles <span class="hlt">caldera</span> and the first continuously cored hole in the <span class="hlt">caldera</span> region. The objectives of VC-1 were to penetrate a hydrothermal outflow plume near its source, to obtain structural and stratigraphic information near the intersection of the ring-fracture zone and the pre-<span class="hlt">caldera</span> Jemez fault zone, and to core the youngest volcanic unit inside the <span class="hlt">caldera</span> (Banco Bonito obsidian, 0.13 Ma). VC-1 penetrates 298 m of moat volcanics and <span class="hlt">caldera</span>-fill ignimbrites, 35 m of pre-<span class="hlt">caldera</span> volcaniclastic breccia, and 523 m of Paleozoic carbonates, sandstones and shales, with over 95% core recovery. Hydrothermal alterations are concentrated in sheared, brecciated and fractured zones from the volcaniclastic breccia to total depth with both the intensity and rank of alterations increasing with depth. Alterations consist primarily of clays, calcite, pyrite, quartz, and chlorite, but chalcopyrite has been identified as high as 518 m and molybdenite has been identified in a fractured zone at 847 m. Thermal aquifers were penetrated at various intervals from about 510 m on down. 11 refs., 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1335788','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1335788"><span>Changes in magma storage conditions following <span class="hlt">caldera</span> collapse at Okataina Volcanic Center, New Zealand</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rubin, Allison; Cooper, Kari M.; Leever, Marissa; Wimpenny, Josh; Deering, Chad; Rooney, Tyrone; Gravley, Darren; Yin, Qing-zhu</p> <p>2015-12-15</p> <p>Large silicic volcanic centers produce both small rhyolitic eruptions and catastrophic <span class="hlt">caldera</span>-forming eruptions. Although changes in trace element and isotopic compositions within eruptions following <span class="hlt">caldera</span> collapse have been observed at rhyolitic volcanic centers such as Yellowstone and Long Valley, much still remains unknown about the ways in which magma reservoirs are affected by <span class="hlt">caldera</span> collapse. We present <sup>238</sup>U–<sup>230</sup>Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanic Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka <span class="hlt">caldera</span>-forming Rotoiti eruption. Our data indicate that (1) mixing of magmas derived from crustal melts and mantle melts takes place within the shallow reservoir; (2) while the basic processes of melt generation likely did not change significantly between pre- and post-<span class="hlt">caldera</span> rhyolites, post-<span class="hlt">caldera</span> zircons show increased trace element and isotopic heterogeneity that suggests a decrease in the degree of interconnectedness of the liquid within the reservoir following collapse; and (3) post-<span class="hlt">caldera</span> eruptions from different vents indicate different storage times of the amalgamated melt prior to eruption. Furthermore, these data further suggest that the timescales needed to generate large volumes of eruptible melt may depend on the timescales needed to increase interconnectedness and achieve widespread homogenization throughout the reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1335788-changes-magma-storage-conditions-following-caldera-collapse-okataina-volcanic-center-new-zealand','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1335788-changes-magma-storage-conditions-following-caldera-collapse-okataina-volcanic-center-new-zealand"><span>Changes in magma storage conditions following <span class="hlt">caldera</span> collapse at Okataina Volcanic Center, New Zealand</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Rubin, Allison; Cooper, Kari M.; Leever, Marissa; ...</p> <p>2015-12-15</p> <p>Large silicic volcanic centers produce both small rhyolitic eruptions and catastrophic <span class="hlt">caldera</span>-forming eruptions. Although changes in trace element and isotopic compositions within eruptions following <span class="hlt">caldera</span> collapse have been observed at rhyolitic volcanic centers such as Yellowstone and Long Valley, much still remains unknown about the ways in which magma reservoirs are affected by <span class="hlt">caldera</span> collapse. We present 238U–230Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanic Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka <span class="hlt">caldera</span>-formingmore » Rotoiti eruption. Our data indicate that (1) mixing of magmas derived from crustal melts and mantle melts takes place within the shallow reservoir; (2) while the basic processes of melt generation likely did not change significantly between pre- and post-<span class="hlt">caldera</span> rhyolites, post-<span class="hlt">caldera</span> zircons show increased trace element and isotopic heterogeneity that suggests a decrease in the degree of interconnectedness of the liquid within the reservoir following collapse; and (3) post-<span class="hlt">caldera</span> eruptions from different vents indicate different storage times of the amalgamated melt prior to eruption. Furthermore, these data further suggest that the timescales needed to generate large volumes of eruptible melt may depend on the timescales needed to increase interconnectedness and achieve widespread homogenization throughout the reservoir.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5266066','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5266066"><span>Lithologic descriptions and temperature profiles of five wells in the southwestern Valles <span class="hlt">caldera</span> region, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shevenell, L.; Goff, F.; Miles, D.; Waibel, A.; Swanberg, C.</p> <p>1988-01-01</p> <p>The subsurface stratigraphy and temperature profiles of the southern and western Valles <span class="hlt">caldera</span> region have been well constrained with the use of data from the VC-1, AET-4, WC 23-4, PC-1 and PC-2 wells. Data from these wells indicate that thermal gradients west of the <span class="hlt">caldera</span> margin are between 110 and 140)degrees)C/km, with a maximum gradient occurring in the bottom of PC-1 equal to 240)degrees)C/km as a result of thermal fluid flow. Gradients within the <span class="hlt">caldera</span> reach a maximum of 350)degrees)C/km, while the maximum thermal gradient measured southwest of the <span class="hlt">caldera</span> in the thermal outflow plume is 140)degrees)C/km. The five wells exhibit high thermal gradients (>60)deghrees)C/km) resulting from high conductive heat flow associated with the Rio Grande rift and volcanism in the Valles <span class="hlt">caldera</span>, as well as high convective heat flow associated with circulating geothermal fluids. Gamma logs run in four of the five wells appear to be of limited use for stratigraphic correlations in the <span class="hlt">caldera</span> region. However, stratigraphic and temperature data from the five wells provide information about the structure and thermal regime of the southern and western Valles <span class="hlt">caldera</span> region. 29 refs., 9 figs. 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoMP..171....4R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoMP..171....4R"><span>Changes in magma storage conditions following <span class="hlt">caldera</span> collapse at Okataina Volcanic Center, New Zealand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rubin, Allison; Cooper, Kari M.; Leever, Marissa; Wimpenny, Josh; Deering, Chad; Rooney, Tyrone; Gravley, Darren; Yin, Qing-zhu</p> <p>2016-01-01</p> <p>Large silicic volcanic centers produce both small rhyolitic eruptions and catastrophic <span class="hlt">caldera</span>-forming eruptions. Although changes in trace element and isotopic compositions within eruptions following <span class="hlt">caldera</span> collapse have been observed at rhyolitic volcanic centers such as Yellowstone and Long Valley, much still remains unknown about the ways in which magma reservoirs are affected by <span class="hlt">caldera</span> collapse. We present 238U-230Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanic Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka <span class="hlt">caldera</span>-forming Rotoiti eruption. Our data indicate that (1) mixing of magmas derived from crustal melts and mantle melts takes place within the shallow reservoir; (2) while the basic processes of melt generation likely did not change significantly between pre- and post-<span class="hlt">caldera</span> rhyolites, post-<span class="hlt">caldera</span> zircons show increased trace element and isotopic heterogeneity that suggests a decrease in the degree of interconnectedness of the liquid within the reservoir following collapse; and (3) post-<span class="hlt">caldera</span> eruptions from different vents indicate different storage times of the amalgamated melt prior to eruption. These data further suggest that the timescales needed to generate large volumes of eruptible melt may depend on the timescales needed to increase interconnectedness and achieve widespread homogenization throughout the reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015005','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015005"><span>A Sr-isotopic comparison between thermal waters, rocks, and hydrothermal calcites, Long Valley <span class="hlt">caldera</span>, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Goff, F.; Wollenberg, H.A.; Brookins, D.C.; Kistler, R.W.</p> <p>1991-01-01</p> <p>The 87Sr/86Sr values of thermal waters and hydrothermal calcites of the Long Valley <span class="hlt">caldera</span> geothermal system are more radiogenic than those of young intracaldera volcanic rocks. Five thermal waters display 87Sr/86Sr of 0.7081-0.7078 but show systematically lighter values from west to east in the direction of lateral flow. We believe the decrease in ratio from west to east signifies increased interaction of deeply circulating thermal water with relatively fresh volcanic rocks filling the <span class="hlt">caldera</span> depression. All types of pre-, syn-, and post-<span class="hlt">caldera</span> volcanic rocks in the west and central <span class="hlt">caldera</span> have (87Sr/86Sr)m between about 0.7060 and 0.7072 and values for Sierra Nevada granodiorites adjacent to the <span class="hlt">caldera</span> are similar. Sierran pre-intrusive metavolcanic and metasedimentary rocks can have considerably higher Sr-isotope ratios (0.7061-0.7246 and 0.7090-0.7250, respectively). Hydrothermally altered volcanic rocks inside the <span class="hlt">caldera</span> have (87Sr/86Sr)m slightly heavier than their fresh volcanic equivalents and hydrothermal calcites (0.7068-0.7105) occupy a midrange of values between the volcanic/plutonic rocks and the Sierran metamorphic rocks. These data indicate that the Long Valley geothermal reservoir is first equilibrated in a basement complex that contains at least some metasedimentary rocks. Reequilibration of Sr-isotope ratios to lower values occurs in thermal waters as convecting geothermal fluids flow through the isotopically lighter volcanic rocks of the <span class="hlt">caldera</span> fill. ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.V11C2797C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V11C2797C"><span>Geology and Geochemistry of the 25.0 Ma Underdown <span class="hlt">Caldera</span> Tuffs and tuff of Clipper Gap, Western Nevada Volcanic Field <span class="hlt">caldera</span> belt, north-central Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cousens, B.; Klausen, K. B.; Henry, C.</p> <p>2016-12-01</p> <p>The 25.0 Ma Underdown <span class="hlt">Caldera</span> of the Shoshone Mountains near Austin, Nevada, is part of the Ignimbrite Flare-up suite of <span class="hlt">calderas</span> in north-central Nevada. Our goal is to characterize the geochemistry and geochronology of the tuffs, determine magma sources, and contrast Underdown with nearby contemporaneous <span class="hlt">caldera</span> suites. The <span class="hlt">caldera</span> is contained within a single, mildly west-tilted fault block (Bonham, 1970). The basement rocks are altered intermediate volcanic rocks, rarely intruded by rhyolite veins. The lowermost <span class="hlt">caldera</span> unit, exposed only on the east side of the fault block, is the sparsely qtz-feld-phyric Underdown Tuff, a high-silica rhyolite (Bonham, 1970) that is columnar-jointed, densely welded, commonly includes aphyric pumice, but locally includes porphyritic pumice. Stretched pumice, flow folds, and foliations that reach nearly vertical demonstrate significant rheomorphism. A densely-welded porphyritic tuff is also present along the southeast side of the exposed <span class="hlt">caldera</span>, and may be either blocks of an older tuff or a porphyritic phase of the Underdown Tuff. Correlative outflow, the tuff of Clipper Gap, emplaced east of the <span class="hlt">caldera</span>, is petrographically similar with the same two pumice types. Overlying the Underdown Tuff is the Bonita Canyon Formation, which is moderately welded, commonly lithic- and pumice-rich with minor biotite, quartz and feldspar crystals, and contains reworked lenses; megabreccia of intermediate volcanic rocks and abundantly porphyritic tuff are common. This formation may be an upper part of the Underdown Tuff. On the west side of the Shoshone Mountains, the Bonita Canyon units are overlain by a more porphyritic, variably pumiceous, commonly vitrophyric, and densely welded tuff. At 24.7 Ma, this tuff is petrographically similar to and may be a younger part of the 25.2 Ma tuff of Arc Dome exposed to the east in the Toiyabe Range. Ongoing dating and geochemical analyses will constrain the timing and relationships between the tuffs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5207064','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5207064"><span>Oligocene volcanism and multiple <span class="hlt">caldera</span> formation in the Chinati Mountains, Presidio County, Texas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cepeda, J.C.; Henry, C.D.</p> <p>1983-01-01</p> <p>The Chinati Mountains <span class="hlt">caldera</span>, which lies in Trans-Pecos Texas in the southern Basin and Range Province, was formed by eruption of the