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Sample records for earthquake landslide volcanic

  1. The susceptibility analysis of landslides induced by earthquake in Aso volcanic area, Japan, scoping the prediction

    NASA Astrophysics Data System (ADS)

    Kubota, Tetsuya; Takeda, Tsuyoshi

    2017-04-01

    Kumamoto earthquake on April 16th 2016 in Kumamoto prefecture, Kyushu Island, Japan with intense seismic scale of M7.3 (maximum acceleration = 1316 gal in Aso volcanic region) yielded countless instances of landslide and debris flow that induced serious damages and causalities in the area, especially in the Aso volcanic mountain range. Hence, field investigation and numerical slope stability analysis were conducted to delve into the characteristics or the prediction factors of the landslides induced by this earthquake. For the numerical analysis, Finite Element Method (FEM) and CSSDP (Critical Slip Surface analysis by Dynamic Programming theory based on limit equilibrium method) were applied to the landslide slopes with seismic acceleration observed. These numerical analysis methods can automatically detect the landslide slip surface which has minimum Fs (factor of safety). The various results and the information obtained through this investigation and analysis were integrated to predict the landslide susceptible slopes in volcanic area induced by earthquakes and rainfalls of their aftermath, considering geologic-geomorphologic features, geo-technical characteristics of the landslides and vegetation effects on the slope stability. Based on the FEM or CSSDP results, the landslides occurred in this earthquake at the mild gradient slope on the ridge have the safety factor of slope Fs=2.20 approximately (without rainfall nor earthquake, and Fs>=1.0 corresponds to stable slope without landslide) and 1.78 2.10 (with the most severe rainfall in the past) while they have approximately Fs=0.40 with the seismic forces in this earthquake (horizontal direction 818 gal, vertical direction -320 gal respectively, observed in the earthquake). It insists that only in case of earthquakes the landslide in volcanic sediment apt to occur at the mild gradient slopes as well as on the ridges with convex cross section. Consequently, the following results are obtained. 1) At volcanic

  2. Swellable clay minerals in weathering products of volcanic sediments related to landslides by 2016 Kumamoto Earthquake

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Torii, M.

    2016-12-01

    2016 Kumamoto Earthquake triggered numerous landslides in Aso caldera area, Japan and incurred heavy casualties. Landslides occurred not only on steep slopes at the caldera cliffs or the barranco but also on relatively gradual slopes at the side of the central cones in the Aso caldera. The Aso volcano is a volcanic complex with huge caldera formed by catastrophic eruption at approximately 90ka and central cones formed by subsequent activities to recent years. The central cones are volcanic peaks contain various rocks including basaltic, andesitic and rhoyolitic lavas and pyroclastic materials. In this study, we analyzed the samples collected from the bottom surface of landslides occurred at the gradual hillside on the western flank of the Aso central cones. The subsurface geology of the site is Takanoobane rhyolite lava, 51ka, covered by dark silty or pelitic tuffs and black soil strata including Kusasenri pumice layer, 31ka. The bottom plane of the landslides can be seen as flat surfaces at boundaries between units in the Kusasenri pumice or bottom of the Kusasenri pumice on the pelitic tuff with charcoaled plants. The Kusasenri pumice layer is a coarse grained and highly permeable but poorly continuous. X-ray diffraction analysis revealed that the main component of the samples is halloysite (10Å). Halloysite (10Å) is alteration product of fine grained volcanic ash, and swellable clay with interlayer water molecules which bring sticky and deformable characteristics. The landslides caused by 2016 Kumamoto Earthquake occurred without precipitation within a week. Strong earthquake may fluidize swellable clay layers in gradual slopes and triggered heavy landslides.

  3. Characteristics of Volcanic Soils in Landslide during the 2016 Kumamoto Earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Hazarika, H.; Fukuoka, H.; Kokusho, T.; Sumartini, O.; Bhoopendra, D.

    2017-12-01

    There were many seismic subsidence, debris flows, landslides and slope failures, which occurred in Aso area due to the 2016 Kumamoto earthquake, Japan. This research aims to determine the failure mechanism of many mild slopes, and elucidate the strength characteristics of volcanic soils collected from the sites. A series of undrained static and cyclic triaxial tests, ring shear tests and direct shear tests were performed. Also, for further understanding of volcanic soils' material strength, X-ray powder diffraction analysis (XRD), X-ray fluorescence analysis (XRF), and Scanning electron microscope analysis (SEM) were performed. In this paper, preliminary results of the experimental testing program are discussed.

  4. Black swans, power laws, and dragon-kings: Earthquakes, volcanic eruptions, landslides, wildfires, floods, and SOC models

    NASA Astrophysics Data System (ADS)

    Sachs, M. K.; Yoder, M. R.; Turcotte, D. L.; Rundle, J. B.; Malamud, B. D.

    2012-05-01

    Extreme events that change global society have been characterized as black swans. The frequency-size distributions of many natural phenomena are often well approximated by power-law (fractal) distributions. An important question is whether the probability of extreme events can be estimated by extrapolating the power-law distributions. Events that exceed these extrapolations have been characterized as dragon-kings. In this paper we consider extreme events for earthquakes, volcanic eruptions, wildfires, landslides and floods. We also consider the extreme event behavior of three models that exhibit self-organized criticality (SOC): the slider-block, forest-fire, and sand-pile models. Since extrapolations using power-laws are widely used in probabilistic hazard assessment, the occurrence of dragon-king events have important practical implications.

  5. Landslides caused by the M 7.6 Tecomán, Mexico earthquake of January 21, 2003

    Keefer, David K.; Wartman, Joseph; Navarro, Ochoa C.; Rodriguez-Marek, Adrian; Wieczorek, Gerald F.

    2006-01-01

    In contrast to the coastal cordilleras, the volcanic rocks to the north were more susceptible to the occurrence of seismically triggered landslides. The greatest number and concentrations of landslides occurred there, and the landslides were larger than those in the coastal cordilleras, even though this volcanic terrain was farther from the earthquake source. Here, stretches of river bluffs several hundred meters long had been stripped of vegetation and surficial material by coalescing landslides, and several days after the main shock, thousands of small rock falls were still occurring each day, indicating an ongoing hazard. The high susceptibility of volcanic materials to earthquake-generated landslides conforms to findings in other recent earthquakes.

  6. Geological control of earthquake induced landslide in El Salvador

    NASA Astrophysics Data System (ADS)

    Tsige Aga, Meaza

    2010-05-01

    Geological control of earthquake induced landslides in El Salvador. M., Tsige(1), I., Garcia-Flórez(1), R., Mateos(2) (1)Universidad Complutense de Madrid, Facultad de Geología, Madrid, Spain, (meaza@geo.ucm.es) (2)IGME, Mallorca El Salvador is located at one of the most seismically active areas en Central America, and suffered severe damage and loss of life in historical and recent earthquakes, as a consequence of earthquake induced landslides. The most common landslides were shallow disrupted soil-slides on steep slopes and were particularly dense in the central part of the country. Most of them are cited in the recent mechanically weak volcanic pyroclastic deposits known as "Tierra Blanca" and "Tierra Color Café" which are prone to seismic wave amplification and are supposed to have contributed to the triggering of some of the hundreds of landslides related to the 2001 (Mw = 7.6 and Mw = 6.7), seismic events. The earthquakes also triggered numerous deep large scale landslides responsible for the enormous devastation of villages and towns and are the source for the current high seismic hazard as well. Many of these landslides are located at distances more than 50 and 100 km from the focal distance, although some of them occurred at near field. Until now there has been little effort to explain the causes and concentration of the deep large-scale landslides especially their distribution, failure mechanism and post-rapture behavior of the landslide mass (long run-out). It has been done a field investigation of landslides, geological materiales and interpretation of aerial photographs taken before and after the two 2001 (Mw= 7.6 and Mw= 6.7) El Salvador earthquakes. The result of the study showed that most of the large-scale landslides occured as coherent block slides with the sliding surface parallel to a pre-existing fractures and fault planes (La Leona, Barriolera, El Desague, Jiboa landslides). Besides that the pre-existing fractures are weak zones controlling

  7. Landslide Hazards After the 2005 Kashmir Earthquake

    NASA Astrophysics Data System (ADS)

    Bulmer, Mark; Farquhar, Tony; Roshan, Masud; Akhtar, Sadar Saeed; Wahla, Sajjad Karamat

    2007-01-01

    The 8 October 2005 Kashmir earthquake killed 87,300 people and disrupted the lives of several million more. By current estimates, 30,000 still live in camps sited more in accordance with short term expedience than with freedom from risk of natural hazards. In December 2006, the international aid community expressed fears that 50,000 people in Northwest Frontier Province may leave their mountain homes this winter as landslides and avalanches block access roads. As the focus of humanitarian assistance shifts toward restoration of Kashmir's infrastructure, it is important that the persistent hazard of landslides within the earthquake affected region be understood and recognized.

  8. Investigating landslides caused by earthquakes - A historical review

    Keefer, D.K.

    2002-01-01

    Post-earthquake field investigations of landslide occurrence have provided a basis for understanding, evaluating, and mapping the hazard and risk associated with earthquake-induced landslides. This paper traces the historical development of knowledge derived from these investigations. Before 1783, historical accounts of the occurrence of landslides in earthquake are typically so incomplete and vague that conclusions based on these accounts are of limited usefulness. For example, the number of landslides triggered by a given event is almost always greatly underestimated. The first formal, scientific post-earthquake investigation that included systematic documentation of the landslides was undertaken in the Calabria region of Italy after the 1783 earthquake swarm. From then until the mid-twentieth century, the best information on earthquake-induced landslides came from a succession of post-earthquake investigations largely carried out by formal commissions that undertook extensive ground-based field studies. Beginning in the mid-twentieth century, when the use of aerial photography became widespread, comprehensive inventories of landslide occurrence have been made for several earthquakes in the United States, Peru, Guatemala, Italy, El Salvador, Japan, and Taiwan. Techniques have also been developed for performing "retrospective" analyses years or decades after an earthquake that attempt to reconstruct the distribution of landslides triggered by the event. The additional use of Geographic Information System (GIS) processing and digital mapping since about 1989 has greatly facilitated the level of analysis that can applied to mapped distributions of landslides. Beginning in 1984, synthesis of worldwide and national data on earthquake-induced landslides have defined their general characteristics and relations between their occurrence and various geologic and seismic parameters. However, the number of comprehensive post-earthquake studies of landslides is still

  9. Investigating Landslides Caused by Earthquakes A Historical Review

    NASA Astrophysics Data System (ADS)

    Keefer, David K.

    Post-earthquake field investigations of landslide occurrence have provided a basis for understanding, evaluating, and mapping the hazard and risk associated withearthquake-induced landslides. This paper traces thehistorical development of knowledge derived from these investigations. Before 1783, historical accounts of the occurrence of landslides in earthquakes are typically so incomplete and vague that conclusions based on these accounts are of limited usefulness. For example, the number of landslides triggered by a given event is almost always greatly underestimated. The first formal, scientific post-earthquake investigation that included systematic documentation of the landslides was undertaken in the Calabria region of Italy after the 1783 earthquake swarm. From then until the mid-twentieth century, the best information on earthquake-induced landslides came from a succession ofpost-earthquake investigations largely carried out by formal commissions that undertook extensive ground-based field studies. Beginning in the mid-twentieth century, when the use of aerial photography became widespread, comprehensive inventories of landslide occurrence have been made for several earthquakes in the United States, Peru, Guatemala, Italy, El Salvador, Japan, and Taiwan. Techniques have also been developed for performing ``retrospective'' analyses years or decades after an earthquake that attempt to reconstruct the distribution of landslides triggered by the event. The additional use of Geographic Information System (GIS) processing and digital mapping since about 1989 has greatly facilitated the level of analysis that can applied to mapped distributions of landslides. Beginning in 1984, syntheses of worldwide and national data on earthquake-induced landslides have defined their general characteristics and relations between their occurrence and various geologic and seismic parameters. However, the number of comprehensive post-earthquake studies of landslides is still

  10. Map of landslides triggered by the January 12, 2010, Haiti earthquake

    Harp, Edwin L.; Jibson, Randall W.; Schmitt, Robert G.

    2016-04-12

    The magnitude (M) 7.0 Haiti earthquake of January 12, 2010, triggered landslides throughout much of Haiti on the island of Hispaniola in the Caribbean Sea. The epicenter of the quake was located at 18.44°N., 72.57°W. at a depth of 13 kilometers (km) approximately 25 km southwest of the capital, Port-au-Prince. Although estimates vary widely, the most reliable surveys of casualties indicate that the earthquake caused 158,679 fatalities and more than 300,000 injuries. The U.S. Geological Survey compared publicly available satellite imagery acquired both before and after the earthquake and mapped 23,567 landslides that were triggered by the strong shaking. Our mapping from aerial photography and satellite imagery was augmented by field observations.Most of the landslides triggered by the earthquake were south of the Léogâne fault on the footwall and were fairly shallow falls and slides in weathered limestone (2–5 meters [m] thick) and volcanic rock and soil (generally <1 m thick). Landslides extended from the north to the south coasts of the southwestern peninsula (southwest of Port-au-Prince) and almost 60 km to the east and west of the epicenter. The highest concentration of landslides was on the steep limestone slopes of incised river valleys, but large numbers of landslides also occurred on gentler slopes in weathered volcanic rocks. Although some high landslide concentrations did occur near areas of maximum fault slip, the overall distribution of landslides appears to involve complex interactions between geology, topography, and strong shaking with limited spatial correlation between fault slip and landslides.

  11. Connectivity of earthquake-triggered landslides with the fluvial network: Implications for landslide sediment transport after the 2008 Wenchuan earthquake

    NASA Astrophysics Data System (ADS)

    Li, Gen; West, A. Joshua; Densmore, Alexander L.; Hammond, Douglas E.; Jin, Zhangdong; Zhang, Fei; Wang, Jin; Hilton, Robert G.

    2016-04-01

    Evaluating the influence of earthquakes on erosion, landscape evolution, and sediment-related hazards requires understanding fluvial transport of material liberated in earthquake-triggered landslides. The location of landslides relative to river channels is expected to play an important role in postearthquake sediment dynamics. In this study, we assess the position of landslides triggered by the Mw 7.9 Wenchuan earthquake, aiming to understand the relationship between landslides and the fluvial network of the steep Longmen Shan mountain range. Combining a landslide inventory map and geomorphic analysis, we quantify landslide-channel connectivity in terms of the number of landslides, landslide area, and landslide volume estimated from scaling relationships. We observe a strong spatial variability in landslide-channel connectivity, with volumetric connectivity (ξ) ranging from ~20% to ~90% for different catchments. This variability is linked to topographic effects that set local channel densities, seismic effects (including seismogenic faulting) that regulate landslide size, and substrate effects that may influence both channelization and landslide size. Altogether, we estimate that the volume of landslides connected to channels comprises 43 + 9/-7% of the total coseismic landslide volume. Following the Wenchuan earthquake, fine-grained (<~0.25 mm) suspended sediment yield across the Longmen Shan catchments is positively correlated to catchment-wide landslide density, but this correlation is statistically indistinguishable whether or not connectivity is considered. The weaker-than-expected influence of connectivity on suspended sediment yield may be related to mobilization of fine-grained landslide material that resides in hillslope domains, i.e., not directly connected to river channels. In contrast, transport of the coarser fraction (which makes up >90% of the total landslide volume) may be more significantly affected by landslide locations.

  12. Prediction of earthquake-triggered landslide event sizes

    NASA Astrophysics Data System (ADS)

    Braun, Anika; Havenith, Hans-Balder; Schlögel, Romy

    2016-04-01

    Seismically induced landslides are a major environmental effect of earthquakes, which may significantly contribute to related losses. Moreover, in paleoseismology landslide event sizes are an important proxy for the estimation of the intensity and magnitude of past earthquakes and thus allowing us to improve seismic hazard assessment over longer terms. Not only earthquake intensity, but also factors such as the fault characteristics, topography, climatic conditions and the geological environment have a major impact on the intensity and spatial distribution of earthquake induced landslides. We present here a review of factors contributing to earthquake triggered slope failures based on an "event-by-event" classification approach. The objective of this analysis is to enable the short-term prediction of earthquake triggered landslide event sizes in terms of numbers and size of the affected area right after an earthquake event occurred. Five main factors, 'Intensity', 'Fault', 'Topographic energy', 'Climatic conditions' and 'Surface geology' were used to establish a relationship to the number and spatial extend of landslides triggered by an earthquake. The relative weight of these factors was extracted from published data for numerous past earthquakes; topographic inputs were checked in Google Earth and through geographic information systems. Based on well-documented recent earthquakes (e.g. Haiti 2010, Wenchuan 2008) and on older events for which reliable extensive information was available (e.g. Northridge 1994, Loma Prieta 1989, Guatemala 1976, Peru 1970) the combination and relative weight of the factors was calibrated. The calibrated factor combination was then applied to more than 20 earthquake events for which landslide distribution characteristics could be cross-checked. One of our main findings is that the 'Fault' factor, which is based on characteristics of the fault, the surface rupture and its location with respect to mountain areas, has the most important

  13. Analysis of Landslides Triggered by October 2005, Kashmir Earthquake

    PubMed Central

    Mahmood, Irfan; Qureshi, Shahid Nadeem; Tariq, Shahina; Atique, Luqman; Iqbal, Muhammad Farooq

    2015-01-01

    Introduction: The October 2005, Kashmir earthquake main event was triggered along the Balakot-Bagh Fault which runs from Bagh to Balakot, and caused more damages in and around these areas. Major landslides were activated during and after the earthquake inflicting large damages in the area, both in terms of infrastructure and casualties. These landslides were mainly attributed to the minimum threshold of the earthquake, geology of the area, climatologic and geomorphologic conditions, mudflows, widening of the roads without stability assessment, and heavy rainfall after the earthquake. These landslides were mainly rock and debris falls. Hattian Bala rock avalanche was largest landslide associated with the earthquake which completely destroyed a village and blocked the valley creating a lake. Discussion: The present study shows that the fault rupture and fault geometry have direct influence on the distribution of landslides and that along the rupture zone a high frequency band of landslides was triggered. There was an increase in number of landslides due to 2005 earthquake and its aftershocks and that most of earthquakes have occurred along faults, rivers and roads. It is observed that the stability of landslide mass is greatly influenced by amplitude, frequency and duration of earthquake induced ground motion. Most of the slope failures along the roads resulted from the alteration of these slopes during widening of the roads, and seepages during the rainy season immediately after the earthquake. Conclusion: Landslides occurred mostly along weakly cemented and indurated rocks, colluvial sand and cemented soils. It is also worth noting that fissures and ground crack which were induced by main and after shock are still present and they pose a major potential threat for future landslides in case of another earthquake activity or under extreme weather conditions. PMID:26366324

  14. Analysis of Landslides Triggered by October 2005, Kashmir Earthquake.

    PubMed

    Mahmood, Irfan; Qureshi, Shahid Nadeem; Tariq, Shahina; Atique, Luqman; Iqbal, Muhammad Farooq

    2015-08-26

    The October 2005, Kashmir earthquake main event was triggered along the Balakot-Bagh Fault which runs from Bagh to Balakot, and caused more damages in and around these areas. Major landslides were activated during and after the earthquake inflicting large damages in the area, both in terms of infrastructure and casualties. These landslides were mainly attributed to the minimum threshold of the earthquake, geology of the area, climatologic and geomorphologic conditions, mudflows, widening of the roads without stability assessment, and heavy rainfall after the earthquake. These landslides were mainly rock and debris falls. Hattian Bala rock avalanche was largest landslide associated with the earthquake which completely destroyed a village and blocked the valley creating a lake. The present study shows that the fault rupture and fault geometry have direct influence on the distribution of landslides and that along the rupture zone a high frequency band of landslides was triggered. There was an increase in number of landslides due to 2005 earthquake and its aftershocks and that most of earthquakes have occurred along faults, rivers and roads. It is observed that the stability of landslide mass is greatly influenced by amplitude, frequency and duration of earthquake induced ground motion. Most of the slope failures along the roads resulted from the alteration of these slopes during widening of the roads, and seepages during the rainy season immediately after the earthquake.  Landslides occurred mostly along weakly cemented and indurated rocks, colluvial sand and cemented soils. It is also worth noting that fissures and ground crack which were induced by main and after shock are still present and they pose a major potential threat for future landslides in case of another earthquake activity or under extreme weather conditions.

  15. Landslides from the February 4, 1976, Guatemala earthquake

    Harp, Edwin L.; Wilson, Raymond C.; Wieczorek, Gerald F.

    1981-01-01

    The M (Richter magnitude) = 7.5 Guatemala earthquake of February 4, 1976, generated more than 10,000 landslides throughout an area of approximately 16,000 km2. These landslides caused hundreds of fatalities as well as extensive property damage. Landslides disrupted both highways and the railroad system and thus severely hindered early rescue efforts. In Guatemala City, extensive property damage and loss of life were due to ground failure beneath dwellings built too close to the edges of steeply incised canyons. We have recorded the distribution of landslides from this earthquake by mapping individual slides at a scale of 1:50,000 for most of the landslide-affected area, using high-altitude aerial photography. The highest density of landslides was in the highlands west of Guatemala City. The predominant types of earthquake-triggered landslides were rock falls and debris slides of less than 15,000 m3 volume; in addition to these smaller landslides, 11 large landslides had volumes of more than 100,000 m3. Several of these large landslides posed special hazards to people and property from lakes impounded by the landslide debris and from the ensuing floods that occurred upon breaching and rapid erosion of the debris. The regional landslide distribution was observed to depend on five major factors: (1) seismic intensity; (2) lithology: 90 percent of all landslides were within Pleistocene pumice deposits; (3) slope steepness; (4) topographic amplification of seismic ground motion; and (5) regional fractures. The presence of preearthquake landslides had no apparent effect on the landslide distribution, and landslide concentration in the Guatemala City area does not correlate with local seismic-intensity data. The landslide concentration, examined at this scale, appears to be governed mainly by lithologic differences within the pumice deposits, preexisting fractures, and amplification of ground motion by topography-all factors related to site conditions.

  16. Landslides Triggered by the 2015 Gorkha, Nepal Earthquake

    NASA Astrophysics Data System (ADS)

    Xu, C.

    2018-04-01

    The 25 April 2015 Gorkha Mw 7.8 earthquake in central Nepal caused a large number of casualties and serious property losses, and also induced numerous landslides. Based on visual interpretation of high-resolution optical satellite images pre- and post-earthquake and field reconnaissance, we delineated 47,200 coseismic landslides with a total distribution extent more than 35,000 km2, which occupy a total area about 110 km2. On the basis of a scale relationship between landslide area (A) and volume (V), V = 1.3147 × A1.2085, the total volume of the coseismic landslides is estimated to be about 9.64 × 108 m3. Calculation yields that the landslide number density, area density, and volume density are 1.32 km-2, 0.31 %, and 0.027 m, respectively. The spatial distribution of these landslides is consistent with that of the mainshock and aftershocks and the inferred causative fault, indicating the effect of the earthquake energy release on the pattern on coseismic landslides. This study provides a new, more detailed and objective inventory of the landslides triggered by the Gorkha earthquake, which would be significant for further study of genesis of coseismic landslides, hazard assessment and the long-term impact of the slope failure on the geological environment in the earthquake-scarred region.

  17. Combining historical and geomorphological information to investigate earthquake induced landslides

    NASA Astrophysics Data System (ADS)

    Cardinali, M.; Ferrari, G.; Galli, M.; Guidoboni, E.; Guzzetti, F.

    2003-04-01

    Landslides are caused by many different triggers, including earthquakes. In Italy, a detailed new generation catalogue of information on historical earthquakes for the period 461 B.C to 1997 is available (Catalogue of Strong Italian Earthquakes from 461 B.C. to 1997, ING-SGA 2000). The catalogue lists 548 earthquakes and provides information on a total of about 450 mass-movements triggered by 118 seismic events. The information on earthquake-induced landslides listed in the catalogue was obtained through the careful scrutiny of historical documents and chronicles, but was rarely checked in the field. We report on an attempt to combine the available historical information on landslides caused by earthquakes with standard geomorphological techniques, including the interpretation of aerial photographs and field surveys, to better determine the location, type and distribution of seismically induced historical slope failures. We present four examples in the Central Apennines. The first example describes a rock slide triggered by the 1279 April 30 Umbria-Marche Apennines earthquake (Io = IX) at Serravalle, along the Chienti River (Central Italy). The landslide is the oldest known earthquake-induced slope failure in Italy. The second example describes the location of 2 large landslides triggered by the 1584 September 10 earthquake (Io = IX) at San Piero in Bagno, along the Savio River (Northern Italy). The landslides were subsequently largely modified by mass movements occurred on 1855 making the recognition of the original seismically induced failures difficult, if not impossible. In the third example we present the geographical distribution of the available information on landslide events triggered by 8 earthquakes in Central Valnerina, in the period 1703 to 1979. A comparison with the location of landslides triggered by the September-October 1997 Umbria-Marche earthquake sequence is presented. The fourth example describes the geographical distribution of the available

  18. Toward a comprehensive areal model of earthquake-induced landslides

    Miles, S.B.; Keefer, D.K.

    2009-01-01

    This paper provides a review of regional-scale modeling of earthquake-induced landslide hazard with respect to the needs for disaster risk reduction and sustainable development. Based on this review, it sets out important research themes and suggests computing with words (CW), a methodology that includes fuzzy logic systems, as a fruitful modeling methodology for addressing many of these research themes. A range of research, reviewed here, has been conducted applying CW to various aspects of earthquake-induced landslide hazard zonation, but none facilitate comprehensive modeling of all types of earthquake-induced landslides. A new comprehensive areal model of earthquake-induced landslides (CAMEL) is introduced here that was developed using fuzzy logic systems. CAMEL provides an integrated framework for modeling all types of earthquake-induced landslides using geographic information systems. CAMEL is designed to facilitate quantitative and qualitative representation of terrain conditions and knowledge about these conditions on the likely areal concentration of each landslide type. CAMEL is highly modifiable and adaptable; new knowledge can be easily added, while existing knowledge can be changed to better match local knowledge and conditions. As such, CAMEL should not be viewed as a complete alternative to other earthquake-induced landslide models. CAMEL provides an open framework for incorporating other models, such as Newmark's displacement method, together with previously incompatible empirical and local knowledge. ?? 2009 ASCE.

  19. Distant, delayed and ancient earthquake-induced landslides

    NASA Astrophysics Data System (ADS)

    Havenith, Hans-Balder; Torgoev, Almaz; Braun, Anika; Schlögel, Romy; Micu, Mihai

    2016-04-01

    On the basis of a new classification of seismically induced landslides we outline particular effects related to the delayed and distant triggering of landslides. Those cannot be predicted by state-of-the-art methods. First, for about a dozen events the 'predicted' extension of the affected area is clearly underestimated. The most problematic cases are those for which far-distant triggering of landslides had been reported, such as for the 1988 Saguenay earthquake. In Central Asia reports for such cases are known for areas marked by a thick cover of loess. One possible contributing effect could be a low-frequency resonance of the thick soils induced by distant earthquakes, especially those in the Pamir - Hindu Kush seismic region. Such deep focal and high magnitude (>>7) earthquakes are also found in Europe, first of all in the Vrancea region (Romania). For this area and others in Central Asia we computed landslide event sizes related to scenario earthquakes with M>7.5. The second particular and challenging type of triggering is the one delayed with respect to the main earthquake event: case histories have been reported for the Racha earthquake in 1991 when several larger landslides only started moving 2 or 3 days after the main shock. Similar observations were also made after other earthquake events in the U.S., such as after the 1906 San Francisco, the 1949 Tacoma, the 1959 Hebgen Lake and the 1983 Bora Peak earthquakes. Here, we will present a series of detailed examples of (partly monitored) mass movements in Central Asia that mainly developed after earthquakes, some even several weeks after the main shock: e.g. the Tektonik and Kainama landslides triggered in 1992 and 2004, respectively. We believe that the development of the massive failures is a consequence of the opening of tension cracks during the seismic shaking and their filling up with water during precipitations that followed the earthquakes. The third particular aspect analysed here is the use of large

  20. Landslide mobility and connectivity with fluvial networks during earthquakes

    NASA Astrophysics Data System (ADS)

    Clark, M. K.; West, A. J.; Li, G.; Roback, K.; Zekkos, D.

    2016-12-01

    In some tectonically active mountain belts, coseismic landslide events displace sediment volumes equal to long-term erosion rates when averaged over typical seismic cycles. However, the contribution of landsliding to total erosional budgets depends critically on the export of landslide debris, which in turn is thought to depend on connectivity of landslides with fluvial channels and the sediment transport capacity of fluvial systems. From the 2015 Mw7.8 Gorkha event in central Nepal, we present connectivity data based on a mapped inventory of nearly 25,000 landslides and compare these results to those from the 2008 Mw7.9 Wenchuan earthquake in China. Landslide runout length in Nepal scales with landslide volume, and has a strong association with slope, elevation and relief. Connectivity is greatest for larger landslides in the high-relief, high-elevation part of the High Himalaya, suggesting that these slope failures may have the most immediate impact on sediment dynamics and cascading hazards, such as landslide reactivation by monsoon rainfall and outburst floods that pose immediate threat to communities far down stream. Although more rare than landslides at lower elevation, large high-elevation landslides that cause outburst flooding due to failure of landslide dams in the upper reaches of large Himalayan rivers may also enhance river incision downstream. The overall high fluvial connectivity (i.e. high percentage of landslide volumes directly intersecting the stream network) of coseismic landsliding in the Gorkha event suggests coupling between the earthquake cycle and sediment/geochemical budgets of fluvial systems in the steep topography of the Himalaya.

  1. Frequency-area distribution of earthquake-induced landslides

    NASA Astrophysics Data System (ADS)

    Tanyas, H.; Allstadt, K.; Westen, C. J. V.

    2016-12-01

    Discovering the physical explanations behind the power-law distribution of landslides can provide valuable information to quantify triggered landslide events and as a consequence to understand the relation between landslide causes and impacts in terms of environmental settings of landslide affected area. In previous studies, the probability of landslide size was utilized for this quantification and the developed parameter was called a landslide magnitude (mL). The frequency-area distributions (FADs) of several landslide inventories were modelled and theoretical curves were established to identify the mL for any landslide inventory. In the observed landslide inventories, a divergence from the power-law distribution was recognized for the small landslides, referred to as the rollover, and this feature was taken into account in the established model. However, these analyses are based on a relatively limited number of inventories, each with a different triggering mechanism. Existing definition of the mL include some subjectivity, since it is based on a visual comparison between the theoretical curves and the FAD of the medium and large landslides. Additionally, the existed definition of mL introduces uncertainty due to the ambiguity in both the physical explanation of the rollover and its functional form. Here we focus on earthquake-induced landslides (EQIL) and aim to provide a rigorous method to estimate the mL and total landslide area of EQIL. We have gathered 36 EQIL inventories from around the globe. Using these inventories, we have evaluated existing explanations of the rollover and proposed an alternative explanation given the new data. Next, we propose a method to define the EQIL FAD curves, mL and to estimate the total landslide area. We utilize the total landslide areas obtained from inventories to compare them with our estimations and to validate our methodology. The results show that we calculate landslide magnitudes more accurately than previous methods.

  2. Landslides triggered by the 1994 Northridge, California, earthquake

    Harp, E.L.; Jibson, R.W.

    1996-01-01

    The 17 January 1994 Northridge, California, earthquake (Mw, = 6.7) triggered more than 11,000 landslides over an area of about 10,000 km2. Most of the landslides were concentrated in a 1000-km2 area that included the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-nominal-scale aerial photography provided by the U.S. Air Force and taken the morning of the earthquake; these mapped landslides were subsequently digitized and plotted in a GIS-based format. Most of the triggered landslides were shallow (1- to 5-m thick), highly disrupted falls and slides within weakly cemented Tertiary to Pleistocene clastic sediment. Average volumes of these types of landslides were less than 1000 m3, but many had volumes exceeding 100,000 m3. The larger disrupted slides commonly had runout paths of more than 50 m, and a few traveled as far as 200 m from the bases of steep parent slopes. Deeper (>5-m thick) rotational slumps and block slides numbered in the tens to perhaps hundreds, a few of which exceeded 100,000 m3 in volume. Most of these were reactivations of previously existing landslides. The largest single landslide triggered by the earthquake was a rotational slump/block slide having a volume of 8 ?? 106 m3. Analysis of the mapped landslide distribution with respect to variations in (1) landslide susceptibility and (2) strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the Los Angeles area.

  3. Inventory of landslides triggered by the 1994 Northridge, California earthquake

    Harp, Edwin L.; Jibson, Randall W.

    1995-01-01

    The 17 January 1994 Northridge, California, earthquake (M=6.7) triggered more than 11,000 landslides over an area of about 10,000 km?. Most of the landslides were concentrated in a 1,000-km? area that includes the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-scale aerial photography provided by the U.S. Air Force and taken the morning of the earthquake; these were subsequently digitized and plotted in a GIS-based format, as shown on the accompanying maps (which also are accessible via Internet). Most of the triggered landslides were shallow (1-5 m), highly disrupted falls and slides in weakly cemented Tertiary to Pleistocene clastic sediment. Average volumes of these types of landslides were less than 1,000 m?, but many had volumes exceeding 100,000 m?. Many of the larger disrupted slides traveled more than 50 m, and a few moved as far as 200 m from the bases of steep parent slopes. Deeper ( >5 m) rotational slumps and block slides numbered in the hundreds, a few of which exceeded 100,000 m? in volume. The largest triggered landslide was a block slide having a volume of 8X10E06 m?. Triggered landslides damaged or destroyed dozens of homes, blocked roads, and damaged oil-field infrastructure. Analysis of landslide distribution with respect to variations in (1) landslide susceptibility and (2) strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the Los Angeles area.

  4. Urban Landslides Induced by the 2004 Niigata-Chuetsu Earthquake

    NASA Astrophysics Data System (ADS)

    Kamai, T.; Trandafir, A. C.; Sidle, R. C.

    2005-05-01

    Landslides triggered by the Chuetsu earthquake occurred in artificial slopes of some new developments in suburban Nagaoka, the largest city in the affected area. The landslides occurred in hilly terrain of the eastern part of Nagaoka between the alluvial plain and Tertiary folded mountains of Yamakoshi. Although the extent of landslides in urban Nagaoka was small compared with landslides on natural slopes (especially near Yamakoshi), they represent an important case study for urban landslide disasters. Slope instabilities in urban residential areas were classified as: A) landslides in steep embankments; B) landslides in gently sloping artificial valley fills; C) re-activation of old landslides; and D) liquefaction in deep artificial valley fills. All these failures occurred in relatively uniform suburban landscapes, which were significantly modified from the original landforms. Recent destructive earthquakes in Japan caused similar types of slope failures in urban regions, suggesting that lessons from past earthquakes were not implemented. The greatest damage due to type-A failures occurred in the 25-yr old Takamachi residential area, where about 70 of 522 homes were judged to be uninhabitable. Before development, this area was an isolated hill (90 m elevation) with an adjacent terrace (60 m elevation) consisting of gravel, sand, and silt of the lower to middle Pleistocene deposits. Development earthworks removed the hill crest and created a wide plateau (70 m elevation); excavated soil was placed on the perimeter as an embankment. During the earthquake, the embankment slope collapsed, including retaining walls, perimeter road, and homes. The most serious damage occurred in five places around the margin of the plateau corresponding to shallow valley fills (5 to 8 m thick). Earthquake response analyses using an equivalent linear model indicated the amplification of seismic waves at the surface of embankment slopes, and the peak earthquake acceleration exceeded 1 G

  5. A review of the 2005 Kashmir earthquake-induced landslides; from a remote sensing prospective

    NASA Astrophysics Data System (ADS)

    Shafique, Muhammad; van der Meijde, Mark; Khan, M. Asif

    2016-03-01

    The 8th October 2005 Kashmir earthquake, in northern Pakistan has triggered thousands of landslides, which was the second major factor in the destruction of the build-up environment, after earthquake-induced ground shaking. Subsequent to the earthquake, several researchers from home and abroad applied a variety of remote sensing techniques, supported with field observations, to develop inventories of the earthquake-triggered landslides, analyzed their spatial distribution and subsequently developed landslide-susceptibility maps. Earthquake causative fault rupture, geology, anthropogenic activities and remote sensing derived topographic attributes were observed to have major influence on the spatial distribution of landslides. These were subsequently used to develop a landslide susceptibility map, thereby demarcating the areas prone to landsliding. Temporal studies monitoring the earthquake-induced landslides shows that the earthquake-induced landslides are stabilized, contrary to earlier belief, directly after the earthquake. The biggest landslide induced dam, as a result of the massive Hattian Bala landslide, is still posing a threat to the surrounding communities. It is observed that remote sensing data is effectively and efficiently used to assess the landslides triggered by the Kashmir earthquake, however, there is still a need of more research to understand the mechanism of intensity and distribution of landslides; and their continuous monitoring using remote sensing data at a regional scale. This paper, provides an overview of remote sensing and GIS applications, for the Kashmir-earthquake triggered landslides, derived outputs and discusses the lessons learnt, advantages, limitations and recommendations for future research.

  6. How unusual is the long-runout of the earthquake-triggered giant Luanshibao landslide, Tibetan Plateau, China?

    NASA Astrophysics Data System (ADS)

    Guo, Changbao; Zhang, Yongshuang; Montgomery, David R.; Du, Yuben; Zhang, Guangze; Wang, Shifeng

    2016-04-01

    In the Tibetan Plateau, active tectonic deformation triggers frequent earthquakes, and giant landslides associated with active faults produce serious consequences. A study of the characteristics and mechanism of a historical long-runout landslide in Luanshibao (LSB), Tibetan Plateau, China, finds a maximum sliding distance (L) of 3.83 km with an elevation drop (H) of 820 m. The landslide volume (V) was ~ 0.64-0.94 × 108 m3, and it produced a long-runout (H/L = 0.21). Recent surface offset along the sinistral strike-slip Litang-Dewu fault passes through the middle part of the landslide, which initiated on the hanging wall of the fault. Geological mapping, geophysical prospecting, trenching, and 14C dating together indicate that the LSB landslide occurred in jointed granite ca. 1980 ± 30 YBP, probably triggered by a large earthquake. Compilation of volume and runout distance data for this landslide and other previously published data for volcanic and nonvolcanic long-runout landslides yields a composite runout length-volume relation (L = 12.52V0.37) that closely predicts runout of the LSB landslide, although substantial variation is noted in runout length around the central tendency.

  7. Development of Tools for the Rapid Assessment of Landslide Potential in Areas Exposed to Intense Storms, Earthquakes, and Other Triggering Mechanisms

    NASA Astrophysics Data System (ADS)

    Highland, Lynn

    2014-05-01

    Landslides frequently occur in connection with other types of hazardous phenomena such as earthquake or volcanic activity and intense rainstorms. Strong shaking, for example, often triggers extensive landslides in mountainous areas, which can then complicate response and compound socio-economic impacts over shaking losses alone. The U.S. Geological Survey (USGS) is exploring different ways to add secondary hazards to its Prompt Assessment of Global Earthquakes for Response (PAGER) system, which has been developed to deliver rapid earthquake impact and loss assessments following significant global earthquakes. The PAGER team found that about 22 percent of earthquakes with fatalities have deaths due to secondary causes, and the percentage of economic losses they incur has not been widely studied, but is probably significant. The current approach for rapid assessment and reporting of the potential and distribution of secondary earthquake-induced landslides involves empirical models that consider ground acceleration, slope, and rock-strength. A complementary situational awareness tool being developed is a region-specific landslide database for the U.S. The latter will be able to define, in a narrative form, the landslide types (debris flows, rock avalanches, shallow versus deep) that generally occur in each area, along with the type of soils, geology and meteorological effects that could have a bearing on soil saturation, and thus susceptibility. When a seismic event occurs in the U.S. and the PAGER system generates web-based earthquake information, these landslide narratives will simultaneously be made available, which will help in the assessment of the nature of landslides in that particular region. This landslide profile database could also be applied to landslide events that are not triggered by earthquake shaking, in conjunction with National Weather Service Alerts and other landslide/debris-flow alerting systems. Currently, prototypes are being developed for both

  8. Optimized volume models of earthquake-triggered landslides

    PubMed Central

    Xu, Chong; Xu, Xiwei; Shen, Lingling; Yao, Qi; Tan, Xibin; Kang, Wenjun; Ma, Siyuan; Wu, Xiyan; Cai, Juntao; Gao, Mingxing; Li, Kang

    2016-01-01

    In this study, we proposed three optimized models for calculating the total volume of landslides triggered by the 2008 Wenchuan, China Mw 7.9 earthquake. First, we calculated the volume of each deposit of 1,415 landslides triggered by the quake based on pre- and post-quake DEMs in 20 m resolution. The samples were used to fit the conventional landslide “volume-area” power law relationship and the 3 optimized models we proposed, respectively. Two data fitting methods, i.e. log-transformed-based linear and original data-based nonlinear least square, were employed to the 4 models. Results show that original data-based nonlinear least square combining with an optimized model considering length, width, height, lithology, slope, peak ground acceleration, and slope aspect shows the best performance. This model was subsequently applied to the database of landslides triggered by the quake except for two largest ones with known volumes. It indicates that the total volume of the 196,007 landslides is about 1.2 × 1010 m3 in deposit materials and 1 × 1010 m3 in source areas, respectively. The result from the relationship of quake magnitude and entire landslide volume related to individual earthquake is much less than that from this study, which reminds us the necessity to update the power-law relationship. PMID:27404212

  9. Optimized volume models of earthquake-triggered landslides.

    PubMed

    Xu, Chong; Xu, Xiwei; Shen, Lingling; Yao, Qi; Tan, Xibin; Kang, Wenjun; Ma, Siyuan; Wu, Xiyan; Cai, Juntao; Gao, Mingxing; Li, Kang

    2016-07-12

    In this study, we proposed three optimized models for calculating the total volume of landslides triggered by the 2008 Wenchuan, China Mw 7.9 earthquake. First, we calculated the volume of each deposit of 1,415 landslides triggered by the quake based on pre- and post-quake DEMs in 20 m resolution. The samples were used to fit the conventional landslide "volume-area" power law relationship and the 3 optimized models we proposed, respectively. Two data fitting methods, i.e. log-transformed-based linear and original data-based nonlinear least square, were employed to the 4 models. Results show that original data-based nonlinear least square combining with an optimized model considering length, width, height, lithology, slope, peak ground acceleration, and slope aspect shows the best performance. This model was subsequently applied to the database of landslides triggered by the quake except for two largest ones with known volumes. It indicates that the total volume of the 196,007 landslides is about 1.2 × 10(10) m(3) in deposit materials and 1 × 10(10) m(3) in source areas, respectively. The result from the relationship of quake magnitude and entire landslide volume related to individual earthquake is much less than that from this study, which reminds us the necessity to update the power-law relationship.

  10. Preliminary results on earthquake triggered landslides for the Haiti earthquake (January 2010)

    NASA Astrophysics Data System (ADS)

    van Westen, Cees; Gorum, Tolga

    2010-05-01

    This study presents the first results on an analysis of the landslides triggered by the Ms 7.0 Haiti earthquake that occurred on January 12, 2010 in the boundary region of the Pacific Plate and the North American plate. The fault is a left lateral strike slip fault with a clear surface expression. According to the USGS earthquake information the Enriquillo-Plantain Garden fault system has not produced any major earthquake in the last 100 years, and historical earthquakes are known from 1860, 1770, 1761, 1751, 1684, 1673, and 1618, though none of these has been confirmed in the field as associated with this fault. We used high resolution satellite imagery available for the pre and post earthquake situations, which were made freely available for the response and rescue operations. We made an interpretation of all co-seismic landslides in the epicentral area. We conclude that the earthquake mainly triggered landslide in the northern slope of the fault-related valley and in a number of isolated area. The earthquake apparently didn't trigger many visible landslides within the slum areas on the slopes in the southern part of Port-au-Prince and Carrefour. We also used ASTER DEM information to relate the landslide occurrences with DEM derivatives.

  11. Predictability of Landslide Timing From Quasi-Periodic Precursory Earthquakes

    NASA Astrophysics Data System (ADS)

    Bell, Andrew F.

    2018-02-01

    Accelerating rates of geophysical signals are observed before a range of material failure phenomena. They provide insights into the physical processes controlling failure and the basis for failure forecasts. However, examples of accelerating seismicity before landslides are rare, and their behavior and forecasting potential are largely unknown. Here I use a Bayesian methodology to apply a novel gamma point process model to investigate a sequence of quasiperiodic repeating earthquakes preceding a large landslide at Nuugaatsiaq in Greenland in June 2017. The evolution in earthquake rate is best explained by an inverse power law increase with time toward failure, as predicted by material failure theory. However, the commonly accepted power law exponent value of 1.0 is inconsistent with the data. Instead, the mean posterior value of 0.71 indicates a particularly rapid acceleration toward failure and suggests that only relatively short warning times may be possible for similar landslides in future.

  12. Effects of the 2016 Kumamoto earthquakes on the Aso volcanic edifice

    NASA Astrophysics Data System (ADS)

    Tajima, Yasuhisa; Hasenaka, Toshiaki; Torii, Masayuki

    2017-05-01

    Large earthquakes occurred in the central part of Kumamoto Prefecture on April 14-16, 2016, causing severe damage to the northern segment of the Hinagu faults and the eastern segment of the Futagawa faults. Earthquake surface ruptures appeared along these faults and on the Aso volcanic edifice, which in turn generated landslides. We conducted landform change analysis of the central cones of Aso volcano by using satellite and aerial photographs. First, we categorized the topographical changes as surface scarps, arc-shaped cracks, and linear cracks. Field survey indicated that landslides caused the scarps and arc-shaped cracks, whereas faulting caused the linear cracks. We discovered a surface rupture concentration zone (RCZ) formed three ruptures bands with many surface ruptures and landslides extending from the west foot to the center of the Aso volcanic edifice. The magmatic volcanic vents that formed during the past 10,000 years are located along the north margin of the RCZ. Moreover, the distribution and dip of the core of rupture concentration zone correspond with the Nakadake craters. We conclude that a strong relationship exists between the volcanic vents and fault structures in the central cones of Aso volcano.[Figure not available: see fulltext.

  13. Landslides Induced by 2015 Gorkha Earthquake and Their Continuous Evolution Post 2015 and 2016-Monsoon

    NASA Astrophysics Data System (ADS)

    Spear, B.; Haritashya, U. K.; Kargel, J. S.

    2017-12-01

    Gorkha Nepal has been a hot bed of landslide activity since the 7.8 magnitude earthquake that occurred on April 25th 2015. Even though previous studies have mapped and analyzed the landslides that were directly related to the earthquake, this research maps and analyzes the landslides that occurred during monsoon or after monsoon season in 2015 and 2016. Specifically, our objectives included monitoring post-earthquake landslide evolution and reactivation. We also observed landslides which occurred in the steep side slopes of various small rivers and threatened to block the flow of river. Consequently, we used Landsat, Sentinel, ASTER and images available at Google Earth Engine to locate, map, and analyze these landslides. Our preliminary result indicates 5,270 landslides, however 957 of these landslides occurred significantly after the earthquake. Of the 957 landslides, 508 of them occurred during the monsoon season of 2015 and 48 in the 2016 monsoon season. As well as locating and mapping these landslides, we were able to identify that there were 22 landslides blocking rivers and 24 were reactivated. Our result and landslide density maps clearly identifies zones that are prone to landslides. For example, the steepest areas, such as the Helambu or Langtang region, have a very high concentration of landslides since the earthquake. Furthermore, landslides with the largest area were often nearby each other in very steep regions. This research can be used to determine which areas in the Gorkha Nepal region are safe to use and which areas are high risk.

  14. Landslides triggered by the 8 October 2005 Kashmir earthquake

    Owen, L.A.; Kamp, U.; Khattak, G.A.; Harp, E.L.; Keefer, D.K.; Bauer, M.A.

    2008-01-01

    The 8 October 2005 Kashmir earthquake triggered several thousand landslides. These were mainly rock falls and debris falls, although translational rock and debris slides also occurred. In addition, a sturzstrom (debris avalanche) comprising ??? 80??million m3 buried four villages and blocked streams to create two lakes. Although landsliding occurred throughout the region, covering an area of > 7500??km2, the failures were highly concentrated, associated with six geomorphic-geologic-anthropogenic settings, including natural failures in (1) highly fractured carbonate rocks comprising the lowest beds in the hanging wall of the likely earthquake fault; (2) Tertiary siliciclastic rocks along antecedent drainages that traverse the Hazara-Kashmir Syntaxis; (3) steep (> 50??) slopes comprising Precambrian and Lower Paleozoic rocks; (4) very steep (?? 50??) lower slopes of fluvially undercut Quaternary valley fills; and (5) ridges and spur crests. The sixth setting was associated with road construction. Extensive fissuring in many of the valley slopes together with the freshly mobilized landslide debris constitutes a potential hazard in the coming snowmelt and monsoon seasons. This study supports the view that earthquake-triggered landslides are highly concentrated in specific zones associated with the lithology, structure, geomorphology, topography, and human presence. ?? 2007 Elsevier B.V. All rights reserved.

  15. Landslides triggered by the October 8, 2005, Pakistan earthquake and associated landslide-dammed reservoirs

    Harp, Edwin L.; Crone, Anthony J.

    2006-01-01

    The October 8, 2005, Kashmir earthquake (M 7.6) triggered several thousand landslides, mainly rock falls and rock slides, in the epicentral area near the cities of Muzafarrabad and Balakot, Pakistan. Most of these were shallow, coalescing rock slides emanating from highly sheared and deformed limestone and dolomite of the Precambrian Muzafarrabad Formation. The largest landslide triggered by the earthquake is located approximately 32 kilometers southeast of Muzafarrabad in a tributary valley of the Jhelum River. This landslide is a debris avalanche of approximately 80 million cubic meters volume within the Miocene Murree Formation consisting of mixed sandstone, mudstone, shale, and limestone. The avalanche buried the village of Dandbeh and resulted in approximately 1,000 fatalities, according to local residents. The avalanche deposit traveled approximately 1.5 kilometers downslope and 300 meters or more up the opposite slope in the adjacent Karli stream drainage and also extended into the Tang stream drainage where the Tang stream joins the Karli drainage. The landslide mass has impounded two lakes within the blocked drainages. The lake in the Karli drainage was approximately 800 meters long and 20 meters deep as of December 19, 2005. The lake in the Tang drainage was approximately 400 meters long and 10 meters deep as of this same date. Downstream populations are at risk from possible flash flooding when these debris dams are overtopped by the reservoir water. The closest village, Hattian, is 2.8 kilometers downstream at the junction of the Jhelum River and the landslide-dammed Karli tributary. Other populations along the Jhelum River may also be at risk. Pakistan military engineers are preparing to construct a spillway within the landslide deposits to lessen the severity of the flood if the lake in the Karli stream drainage breaches the landslide dam catastrophically.

  16. Earthquake induced landslide hazard field observatory in the Avcilar peninsula

    NASA Astrophysics Data System (ADS)

    Bigarre, Pascal; Coccia, Stella; Theoleyre, Fiona; Ergintav, Semih; Özel, Oguz; Yalçinkaya, Esref; Lenti, Luca; Martino, Salvatore; Gamba, Paolo; Zucca, Francesco; Moro, Marco

    2015-04-01

    Earthquake-triggered landslides have an increasing disastrous impact in seismic regions due to the fast growing urbanization and infrastructures. Just considering disasters from the last fifteen years, among which the 1999 Chi-Chi earthquake, the 2008 Wenchuan earthquake, and the 2011 Tohoku earthquake, these events generated tens of thousands of coseismic landslides. Those resulted in amazing death toll and considerable damages, affecting the regional landscape including its hydrological main features. Despite a strong impetus in research during past decades, knowledge on those geohazards is still fragmentary, while databases of high quality observational data are lacking. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. The MARSITE project gathers research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Besides the seismic threat, landslides in Turkey and in this region constitute an important source of loss. The 6th Work Package of MARSITE project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest among which the Cekmece-Avcilar peninsula, located westwards of Istanbul, as a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. A multidisciplinary research program based on pre-existing studies has been designed with objectives and tasks linked to constrain and tackle progressively some challenging issues related to data integration, modeling, monitoring and mapping technologies. Since the start of the project, progress has been marked on several important points as follows. The photogeological interpretation and analysis of ENVISAT-ERS DIn

  17. Reactivation of slow-moving landslides by earthquakes, kinematics measurements and mechanical implications

    NASA Astrophysics Data System (ADS)

    Lacroix, Pascal; Perfettini, Hugo; Berthier, Etienne; Taipe, Edu; Guillier, Bertrand

    2015-04-01

    Major earthquakes in mountainous areas often trigger landslides. The impact of earthquakes on slow-moving landslides is however not well constrained due to few co-seismic measurements of landslide motion. We document the first time-series of a landslide reactivation by an earthquake (Mw6.0, distance 20 km), using continuous GPS measurements over the Maca landslide (Peru). Our survey shows a coseismic response of the landslide of about 2 cm, followed by a relaxation period of 5 weeks during which postseismic slip is three times greater than the coseismic displacement itself. Our results confirm the coseismic activation of landslides and provide the first observation of a post seismic displacement. Finally, a multi-temporal survey using images from the very high resolution Pléiades optical satellite, allowed us to detect 9 active slow-moving landslides over the whole valley. Their pattern of motion show they have been reactivated by the same earthquake. We analyze this small but comprehensive database of landslides reactivated by the earthquake. We find that the landslide motion due to the earthquake is function of the shaking intensity, suggesting a friction at the basal interface dependent on the earthquake solicitation. These various observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction, analogous to the mechanics of creeping tectonic faults.

  18. Landslides and Earthquake Lakes from the Wenchuan, China Earthquake - Can it Happen in the U.S.?

    NASA Astrophysics Data System (ADS)

    Stenner, H.; Cydzik, K.; Hamilton, D.; Cattarossi, A.; Mathieson, E.

    2008-12-01

    The May 12, 2008 M7.9 Wenchuan, China earthquake destroyed five million homes and schools, causing over 87,650 deaths. Landslides, a secondary effect of the shaking, caused much of the devastation. Debris flows buried homes, rock falls crushed cars, and landslides dammed rivers. Blocked roads greatly impeded emergency access, delaying response. Our August 2008 field experience in the affected area reminded us that the western United States faces serious risks posed by earthquake-induced landslides. The topography of the western U.S. is less extreme than that near Wenchuan, but earthquakes may still cause devastating landslides, damming rivers and blocking access to affected areas. After the Wenchuan earthquake, lakes rapidly rose behind landslide dams, threatening millions of lives. One landslide above Beichuan City created Tangjiashan Lake, a massive body of water upstream of Mianyang, an area with 5.2 million people, 30,000 of whom were killed in the quake. Potential failure of the landslide dam put thousands more people at risk from catastrophic flooding. In 1959, the M7.4 Hebgen Lake earthquake in Montana caused a large landslide, which killed 19 people and dammed the Madison River. The Army Corps excavated sluices to keep the dam from failing catastrophically. The Hebgen Lake earthquake ultimately caused 28 deaths, mostly from landslides, but the affected region was sparsely populated. Slopes prone to strong earthquake shaking and landslides in California, Washington, and Oregon have much larger populations at risk. Landslide hazards continue after the earthquake due to the effect strong shaking has on hillslopes, particularly when subjected to subsequent rain. These hazards must be taken into account. Once a landslide blocks a river, rapid and thoughtful action is needed. The Chinese government quickly and safely mitigated landslide dams that posed the greatest risk to people downstream. It took expert geotechnical advice, the speed and resources of the army

  19. Cascading hazards: Understanding triggering relations between wet tropical cyclones, landslides, and earthquakes

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Peng, Z.; Ferrier, K.; Lin, C. H.; Hsu, Y. J.; Shyu, J. B. H.

    2017-12-01

    Earthquakes, landslides, and tropical cyclones are extreme hazards that pose significant threats to human life and property. Some of the couplings between these hazards are well known. For example, sudden, widespread landsliding can be triggered by large earthquakes and by extreme rainfall events like tropical cyclones. Recent studies have also shown that earthquakes can be triggered by erosional unloading over 100-year timescales. In a NASA supported project, titled "Cascading hazards: Understanding triggering relations between wet tropical cyclones, landslides, and earthquake", we study triggering relations between these hazard types. The project focuses on such triggering relations in Taiwan, which is subjected to very wet tropical storms, landslides, and earthquakes. One example for such triggering relations is the 2009 Morakot typhoon, which was the wettest recorded typhoon in Taiwan (2850 mm of rain in 100 hours). The typhoon caused widespread flooding and triggered more than 20,000 landslides, including the devastating Hsiaolin landslide. Six months later, the same area was hit by the 2010 M=6.4 Jiashian earthquake near Kaohsiung city, which added to the infrastructure damage induced by the typhoon and the landslides. Preliminary analysis of temporal relations between main-shock earthquakes and the six wettest typhoons in Taiwan's past 50 years reveals similar temporal relations between M≥5 events and wet typhoons. Future work in the project will include remote sensing analysis of landsliding, seismic and geodetic monitoring of landslides, detection of microseismicity and tremor activities, and mechanical modeling of crustal stress changes due to surface unloading.

  20. Comprehensive Areal Model of Earthquake-Induced Landslides: Technical Specification and User Guide

    Miles, Scott B.; Keefer, David K.

    2007-01-01

    This report describes the complete design of a comprehensive areal model of earthquakeinduced landslides (CAMEL). This report presents the design process, technical specification of CAMEL. It also provides a guide to using the CAMEL source code and template ESRI ArcGIS map document file for applying CAMEL, both of which can be obtained by contacting the authors. CAMEL is a regional-scale model of earthquake-induced landslide hazard developed using fuzzy logic systems. CAMEL currently estimates areal landslide concentration (number of landslides per square kilometer) of six aggregated types of earthquake-induced landslides - three types each for rock and soil.

  1. Classification of Earthquake-triggered Landslide Events - Review of Classical and Particular Cases

    NASA Astrophysics Data System (ADS)

    Braun, A.; Havenith, H. B.; Schlögel, R.

    2016-12-01

    Seismically induced landslides often contribute to a significant degree to the losses related to earthquakes. The identification of possible extends of landslide affected areas can help to target emergency measures when an earthquake occurs or improve the resilience of inhabited areas and critical infrastructure in zones of high seismic hazard. Moreover, landslide event sizes are an important proxy for the estimation of the intensity and magnitude of past earthquakes in paleoseismic studies, allowing us to improve seismic hazard assessment over longer terms. Not only earthquake intensity, but also factors such as the fault characteristics, topography, climatic conditions and the geological environment have a major impact on the intensity and spatial distribution of earthquake induced landslides. Inspired by classical reviews of earthquake induced landslides, e.g. by Keefer or Jibson, we present here a review of factors contributing to earthquake triggered slope failures based on an `event-by-event' classification approach. The objective of this analysis is to enable the short-term prediction of earthquake triggered landslide event sizes in terms of numbers and size of the affected area right after an earthquake event occurred. Five main factors, `Intensity', `Fault', `Topographic energy', `Climatic conditions' and `Surface geology' were used to establish a relationship to the number and spatial extend of landslides triggered by an earthquake. Based on well-documented recent earthquakes (e.g. Haiti 2010, Wenchuan 2008) and on older events for which reliable extensive information was available (e.g. Northridge 1994, Loma Prieta 1989, Guatemala 1976, Peru 1970) the combination and relative weight of the factors was calibrated. The calibrated factor combination was then applied to more than 20 earthquake events for which landslide distribution characteristics could be crosschecked. We present cases where our prediction model performs well and discuss particular cases

  2. Assessment of earthquake-induced landslides hazard in El Salvador after the 2001 earthquakes using macroseismic analysis

    NASA Astrophysics Data System (ADS)

    Esposito, Eliana; Violante, Crescenzo; Giunta, Giuseppe; Ángel Hernández, Miguel

    2016-04-01

    Two strong earthquakes and a number of smaller aftershocks struck El Salvador in the year 2001. The January 13 2001 earthquake, Mw 7.7, occurred along the Cocos plate, 40 km off El Salvador southern coast. It resulted in about 1300 deaths and widespread damage, mainly due to massive landsliding. Two of the largest earthquake-induced landslides, Las Barioleras and Las Colinas (about 2x105 m3) produced major damage to buildings and infrastructures and 500 fatalities. A neighborhood in Santa Tecla, west of San Salvador, was destroyed. The February 13 2001 earthquake, Mw 6.5, occurred 40 km east-southeast of San Salvador. This earthquake caused over 300 fatalities and triggered several landslides over an area of 2,500 km2 mostly in poorly consolidated volcaniclastic deposits. The La Leona landslide (5-7x105 m3) caused 12 fatalities and extensive damage to the Panamerican Highway. Two very large landslides of 1.5 km3 and 12 km3 produced hazardous barrier lakes at Rio El Desague and Rio Jiboa, respectively. More than 16.000 landslides occurred throughout the country after both quakes; most of them occurred in pyroclastic deposits, with a volume less than 1x103m3. The present work aims to define the relationship between the above described earthquake intensity, size and areal distribution of induced landslides, as well as to refine the earthquake intensity in sparsely populated zones by using landslide effects. Landslides triggered by the 2001 seismic sequences provided useful indication for a realistic seismic hazard assessment, providing a basis for understanding, evaluating, and mapping the hazard and risk associated with earthquake-induced landslides.

  3. GIS-based landslide susceptibility mapping for the 2005 Kashmir earthquake region

    NASA Astrophysics Data System (ADS)

    Kamp, Ulrich; Growley, Benjamin J.; Khattak, Ghazanfar A.; Owen, Lewis A.

    2008-11-01

    The Mw 7.6 October 8, 2005 Kashmir earthquake triggered several thousand landslides throughout the Himalaya of northern Pakistan and India. These were concentrated in six different geomorphic-geologic-anthropogenic settings. A spatial database, which included 2252 landslides, was developed and analyzed using ASTER satellite imagery and geographical information system (GIS) technology. A multi-criterion evaluation was applied to determine the significance of event-controlling parameters in triggering the landslides. The parameters included lithology, faults, slope gradient, slope aspect, elevation, land cover, rivers and roads. The results showed four classes of landslide susceptibility. Furthermore, they indicated that lithology had the strongest influence on landsliding, particularly when the rock is highly fractured, such as in shale, slate, clastic sediments, and limestone and dolomite. Moreover, the proximity of the landslides to faults, rivers, and roads was also an important factor in helping to initiate failures. In addition, landslides occurred particularly in moderate elevations on south facing slopes. Shrub land, grassland, and also agricultural land were highly susceptible to failures, while forested slopes had few landslides. One-third of the study area was highly or very highly susceptible to future landsliding and requires immediate mitigation action. The rest of the region had a low or moderate susceptibility to landsliding and remains relatively stable. This study supports the view that (1) earthquake-triggered landslides are concentrated in specific zones associated with event-controlling parameters; and (2) in the western Himalaya deforestation and road construction contributed significantly to landsliding during and shortly after earthquakes.

  4. Controls of earthquake faulting style on near field landslide triggering: The role of coseismic slip

    NASA Astrophysics Data System (ADS)

    Tatard, L.; Grasso, J. R.

    2013-06-01

    compare the spatial distributions of seven databases of landslides triggered by Mw=5.6-7.9 earthquakes, using distances normalized by the earthquake fault length. We show that the normalized landslide distance distributions collapse, i.e., the normalized distance distributions overlap whatever the size of the earthquake, separately for the events associated with dip-slip, buried-faulting earthquakes, and surface-faulting earthquakes. The dip-slip earthquakes triggered landslides at larger normalized distances than the oblique-slip event of Loma Prieta. We further identify that the surface-faulting earthquakes of Wenchuan, Chi-Chi, and Kashmir triggered landslides at normalized distances smaller than the ones expected from their Mw ≥ 7.6 magnitudes. These results support a control of the seismic slip (through amplitude, rake, and surface versus buried slip) on the distances at which landslides are triggered. In terms of coseismic landslide management in mountainous areas, our results allow us to propose distances at which 95 and 75% of landslides will be triggered as a function of the earthquake focal mechanism.

  5. Geophysics of Volcanic Landslide Hazards: The Inside Story

    NASA Astrophysics Data System (ADS)

    Finn, C.; Deszcz-Pan, M.; Bedrosian, P. A.

    2013-05-01

    Flank collapses of volcanoes pose significant potential hazards, including triggering lahars, eruptions, and tsunamis. Significant controls on the stability of volcanoes are the distribution of hydrothermal alteration and the location of groundwater. Groundwater position, abundance, and flow rates within a volcano affect the transmission of fluid pressure and the transport of mass and heat. Interaction of groundwater with acid magmatic gases can lead to hydrothermal alteration that mechanically weakens rocks and makes them prone to failure and flank collapse. Therefore, detecting the presence and volume of hydrothermally altered rocks and shallow ground water is critical for evaluating landslide hazards. High-resolution helicopter magnetic and electromagnetic (HEM) data collected over the rugged, ice-covered Mount Adams, Mount Baker, Mount Rainier, Mount St. Helens (Washington) and Mount Iliamna (Alaska) volcanoes, reveal the distribution of alteration, water and ice thickness essential to evaluating volcanic landslide hazards. These data, combined with geological mapping, other geophysical data and rock property measurements, indicate the presence of appreciable thicknesses (>500 m) of water-saturated hydrothermally altered rock west of the modern summit of Mount Rainier in the Sunset Amphitheater region and in the central core of Mount Adams north of the summit. Water-saturated alteration at Mount Baker is restricted to thinner (<200 m) zones beneath Sherman Crater and the Dorr Fumarole Fields. The HEM data can be used to identify water-saturated fresh volcanic rocks from the surface to the detection limit (~100-200 m) in discreet zones on the summits of Mount Rainier and Mt Adams, in shattered fresh dome rocks under the crater of Mount St. Helens and in the entire summit region at Mount Baker. A 50-100 m thick water saturated layer is imaged within or beneath parts of glaciers on Mount Iliamna. Removal of ice and snow during eruptions and landslide can result in

  6. Analysis of post-earthquake landslide activity and geo-environmental effects

    NASA Astrophysics Data System (ADS)

    Tang, Chenxiao; van Westen, Cees; Jetten, Victor

    2014-05-01

    Large earthquakes can cause huge losses to human society, due to ground shaking, fault rupture and due to the high density of co-seismic landslides that can be triggered in mountainous areas. In areas that have been affected by such large earthquakes, the threat of landslides continues also after the earthquake, as the co-seismic landslides may be reactivated by high intensity rainfall events. Earthquakes create Huge amount of landslide materials remain on the slopes, leading to a high frequency of landslides and debris flows after earthquakes which threaten lives and create great difficulties in post-seismic reconstruction in the earthquake-hit regions. Without critical information such as the frequency and magnitude of landslides after a major earthquake, reconstruction planning and hazard mitigation works appear to be difficult. The area hit by Mw 7.9 Wenchuan earthquake in 2008, Sichuan province, China, shows some typical examples of bad reconstruction planning due to lack of information: huge debris flows destroyed several re-constructed settlements. This research aim to analyze the decay in post-seismic landslide activity in areas that have been hit by a major earthquake. The areas hit by the 2008 Wenchuan earthquake will be taken a study area. The study will analyze the factors that control post-earthquake landslide activity through the quantification of the landslide volume changes well as through numerical simulation of their initiation process, to obtain a better understanding of the potential threat of post-earthquake landslide as a basis for mitigation planning. The research will make use of high-resolution stereo satellite images, UAV and Terrestrial Laser Scanning(TLS) to obtain multi-temporal DEM to monitor the change of loose sediments and post-seismic landslide activities. A debris flow initiation model that incorporates the volume of source materials, vegetation re-growth, and intensity-duration of the triggering precipitation, and that evaluates

  7. Microscopic Evolution of Laboratory Volcanic Hybrid Earthquakes

    PubMed Central

    Ghaffari, H. O.; Griffith, W. A.; Benson, P. M.

    2017-01-01

    Characterizing the interaction between fluids and microscopic defects is one of the long-standing challenges in understanding a broad range of cracking processes, in part because they are so difficult to study experimentally. We address this issue by reexamining records of emitted acoustic phonon events during rock mechanics experiments under wet and dry conditions. The frequency spectrum of these events provides direct information regarding the state of the system. Such events are typically subdivided into high frequency (HF) and low frequency (LF) events, whereas intermediate “Hybrid” events, have HF onsets followed by LF ringing. At a larger scale in volcanic terranes, hybrid events are used empirically to predict eruptions, but their ambiguous physical origin limits their diagnostic use. By studying acoustic phonon emissions from individual microcracking events we show that the onset of a secondary instability–related to the transition from HF to LF–occurs during the fast equilibration phase of the system, leading to sudden increase of fluid pressure in the process zone. As a result of this squeezing process, a secondary instability akin to the LF event occurs. This mechanism is consistent with observations of hybrid earthquakes. PMID:28074878

  8. Chapter C. The Loma Prieta, California, Earthquake of October 17, 1989 - Landslides

    Keefer, David K.

    1998-01-01

    Central California, in the vicinity of San Francisco and Monterey Bays, has a history of fatal and damaging landslides, triggered by heavy rainfall, coastal and stream erosion, construction activity, and earthquakes. The great 1906 San Francisco earthquake (MS=8.2-8.3) generated more than 10,000 landslides throughout an area of 32,000 km2; these landslides killed at least 11 people and caused substantial damage to buildings, roads, railroads, and other civil works. Smaller numbers of landslides, which caused more localized damage, have also been reported from at least 20 other earthquakes that have occurred in the San Francisco Bay-Monterey Bay region since 1838. Conditions that make this region particularly susceptible to landslides include steep and rugged topography, weak rock and soil materials, seasonally heavy rainfall, and active seismicity. Given these conditions and history, it was no surprise that the 1989 Loma Prieta earthquake generated thousands of landslides throughout the region. Landslides caused one fatality and damaged at least 200 residences, numerous roads, and many other structures. Direct damage from landslides probably exceeded $30 million; additional, indirect economic losses were caused by long-term landslide blockage of two major highways and by delays in rebuilding brought about by concern over the potential long-term instability of some earthquake-damaged slopes.

  9. Effect of water content on stability of landslides triggered by earthquakes

    NASA Astrophysics Data System (ADS)

    Beyabanaki, S.; Bagtzoglou, A. C.; Anagnostou, E. N.

    2013-12-01

    Earthquake- triggered landslides are one of the most important natural hazards that often result in serious structural damage and loss of life. They are widely studied by several researchers. However, less attention has been focused on soil water content. Although the effect of water content has been widely studied for rainfall- triggered landslides [1], much less attention has been given to it for stability analysis of earthquake- triggered landslides. We developed a combined hydrology and stability model to investigate effect of soil water content on earthquake-triggered landslides. For this purpose, Bishop's method is used to do the slope stability analysis and Richard's equation is employed to model infiltration. Bishop's method is one the most widely methods used for analyzing stability of slopes [2]. Earthquake acceleration coefficient (EAC) is also considered in the model to analyze the effect of earthquake on slope stability. Also, this model is able to automatically determine geometry of the potential landslide. In this study, slopes with different initial water contents are simulated. First, the simulation is performed in the case of earthquake only with different EACs and water contents. As shown in Fig. 1, initial water content has a significant effect on factor of safety (FS). Greater initial water contents lead to less FS. This impact is more significant when EAC is small. Also, when initial water content is high, landslides can happen even with small earthquake accelerations. Moreover, in this study, effect of water content on geometry of landslides is investigated. For this purpose, different cases of landslides triggered by earthquakes only and both rainfall and earthquake for different initial water contents are simulated. The results show that water content has more significant effect on geometry of landslides triggered by rainfall than those triggered by an earthquake. Finally, effect of water content on landslides triggered by earthquakes

  10. Catastrophic debris flows transformed from landslides in volcanic terrains : mobility, hazard assessment and mitigation strategies

    Scott, Kevin M.; Macias, Jose Luis; Naranjo, Jose Antonio; Rodriguez, Sergio; McGeehin, John P.

    2001-01-01

    Communities in lowlands near volcanoes are vulnerable to significant volcanic flow hazards in addition to those associated directly with eruptions. The largest such risk is from debris flows beginning as volcanic landslides, with the potential to travel over 100 kilometers. Stratovolcanic edifices commonly are hydrothermal aquifers composed of unstable, altered rock forming steep slopes at high altitudes, and the terrain surrounding them is commonly mantled by readily mobilized, weathered airfall and ashflow deposits. We propose that volcano hazard assessments integrate the potential for unanticipated debris flows with, at active volcanoes, the greater but more predictable potential of magmatically triggered flows. This proposal reinforces the already powerful arguments for minimizing populations in potential flow pathways below both active and selected inactive volcanoes. It also addresses the potential for volcano flank collapse to occur with instability early in a magmatic episode, as well as the 'false-alarm problem'-the difficulty in evacuating the potential paths of these large mobile flows. Debris flows that transform from volcanic landslides, characterized by cohesive (muddy) deposits, create risk comparable to that of their syneruptive counterparts of snow and ice-melt origin, which yield noncohesive (granular) deposits, because: (1) Volcano collapses and the failures of airfall- and ashflow-mantled slopes commonly yield highly mobile debris flows as well as debris avalanches with limited runout potential. Runout potential of debris flows may increase several fold as their volumes enlarge beyond volcanoes through bulking (entrainment) of sediment. Through this mechanism, the runouts of even relatively small collapses at Cascade Range volcanoes, in the range of 0.1 to 0.2 cubic kilometers, can extend to populated lowlands. (2) Collapse is caused by a variety of triggers: tectonic and volcanic earthquakes, gravitational failure, hydrovolcanism, and

  11. Earthquakes, Subaerial and Submarine Landslides, Tsunamis and Volcanoes in Aysén Fjord, Chile

    NASA Astrophysics Data System (ADS)

    Lastras, G.; Amblas, D.; Calafat-Frau, A. M.; Canals, M.; Frigola, J.; Hermanns, R. L.; Lafuerza, S.; Longva, O.; Micallef, A.; Sepulveda, S. A.; Vargas Easton, G.; Azpiroz, M.; Bascuñán, I.; Duhart, P.; Iglesias, O.; Kempf, P.; Rayo, X.

    2014-12-01

    The Aysén fjord, 65 km long and east-west oriented, is located at 45.4ºS and 73.2ºW in Chilean Patagonia. It has a maximum water depth of 345 m. It collects the inputs of Aysén, Pescado, Condor and Cuervo rivers, which drain the surrounding Patagonian Andes. The fjord is crossed by the Liquiñe-Ofqui Fault Zone, a seismically active trench parallel intra-arc fault system. On 21 April 2007, an Mw 6.2 earthquake triggered numerous subaerial and submarine landslides along the fjord flanks. Some of the subaerial landslides reached the water mass, generating tsunami-like displacement waves that flooded the adjacent coastlines, withlocal >50 m high run-ups, causing ten fatalities and damage to salmon farms. The research cruise DETSUFA on board BIO Hespérides in March 2013, aiming to characterise the landslides and their effects, mapped with great detail the submerged morphology of the fjord. Multibeam data display deformation structures created by the impact of the landslides in the inner fjord floor. Landslide material descended and accelerated down the highly sloping fjord flanks, and reached the fjord floor at 200 m water depth generating large, 10-m-deep impact depressions. Fjord floor sediment was pushed and piled up in arcuate deformation areas formed by 15-m-high compressional ridges, block fields and a narrow frontal depression. Up to six >1.5 km2 of these structures have been identified. In addition, the cruise mapped the outer fjord floor beyond the Cuervo ridge. This ridge, previously interpreted as a volcanic transverse structure, most probably acted as a limit for grounding ice in the past, as suggested by the presence of a melt-water channel. The fjord smoothens and deepens to more than 330 m forming an enclosed basin, before turning SW across a field of streamlined hills of glacial origin. Three volcanic cones, one of them forming Isla Colorada and the other two totally submerged and previously unknown, have been mapped in the outer fjord. The largest

  12. Regional patterns of earthquake-triggered landslides and their relation to ground motion

    NASA Astrophysics Data System (ADS)

    Meunier, Patrick; Hovius, Niels; Haines, A. John

    2007-10-01

    We have documented patterns of landsliding associated with large earthquakes on three thrust faults: the Northridge earthquake in California, Chi-Chi earthquake in Taiwan, and two earthquakes on the Ramu-Markham fault bounding the Finisterre Mountains of Papua New Guinea. In each case, landslide densities are shown to be greatest in the area of strongest ground acceleration and to decay with distance from the epicenter. In California and Taiwan, the density of co-seismic landslides is linearly and highly correlated with both the vertical and horizontal components of measured peak ground acceleration. Based on this observation, we derive an expression for the spatial variation of landslide density analogous with regional seismic attenuation laws. In its general form, this expression applies to our three examples, and we determine best fit values for individual cases. Our findings open a window on the construction of shake maps from geomorphic observations for earthquakes in non-instrumented regions.

  13. Geomorphology and failure history of the earthquake-induced Farmington Siding landslide complex, Davis County, Utah

    SciT

    Lowe, M.; Harty, K.M.

    1993-04-01

    The Farmington Siding landslide complex covers an area of 19.5 km[sup 2] in central Davis County. First identified and mapped in the 1970s, the feature was classified by previous researchers as a liquefaction-induced lateral spread based on surface geomorphology and exposures on the landslide complex. This was the first landslide in Utah to be attributed to earthquake-induced liquefaction. Geomorphic and geologic evidence indicate that the Farmington Sliding landslide complex likely consists of liquefaction-induced landslides that failed by means of both flow failure and lateral spreading. The landslide complex is located in an area underlain primarily by fine-grained deposits of Pleistocenemore » Lake Bonneville and Holocene Great Salt Lake. Geomorphic features of the landslide complex include main and minor scarps, hummocks, closed depressions, and transverse lineaments. The main scarp consists mostly of a series of arcuate scallops near the left flank of the landslide, but it is a relatively linear, single scarp near the right flank of the landslide. Hummocks and closed depressions are most common near the head region of the landslide complex. Failure of the Farmington Sliding landslide complex has occurred at least twice. The older, distal portion of the landslide complex is cut by the Gilbert shoreline of the Bonneville lake cycle, indicating that landsliding occurred more than 10,000 years ago. In the younger portion of the landslide complex, landsliding has disrupted the Gilbert shoreline. Radiocarbon age estimates from trenches on a hummock near the main scarp of the younger landslide indicate that slope failure occurred sometime between about 2,730 [+-] 370 cal. yr B.P. and 4,530 [+-] 300 cal. yr B.P., possibly during the penultimate or antepenultimate surface-faulting earthquake on the Weber segment of the Wasatch fault zone.« less

  14. Investigating Earthquake-induced Landslides­a Historical Review

    NASA Astrophysics Data System (ADS)

    Keefer, D. K.; Geological Survey, Us; Park, Menlo; Usa, Ca

    Although earthquake-induced landslides have been described in documents for more than 3700 years, accounts from earthquakes before the late eighteenth century are incomplete concerning landslide numbers and vague concerning landslide character- istics. They are thus typically misleading concerning the true abundance of landslides and range of landslide characteristics. Beginning with studies of the 1783 Calabria, Italy earthquake, more complete and precise data concerning the occurrence of land- slides in earthquakes have become available. The historical development of knowl- edge concerning landslides triggered by earthquakes can be divided into several peri- ods. The first period, from 1783 until the first application of aerial photography, was characterized by ground-based studies of earthquake effects, typically carried out by formal scientific commissions. These formal studies typically identified a large, but not necessarily comprehensive, sampling of localities where landslides had occurred. In some, but not all cases, landslide characteristics were also described in enough de- tail that the general range of landslide characteristics could begin to be determined. More recently, some nineteenth to mid-twentieth century earthquakes have been stud- ied using retrospective analyses, in which the landslide occurrences associated with the event are inferred years to decades later, using contemporary accounts, mapping from aerial photographs, statistical studies, and (or) geotechnical analyses. The first use of aerial photographs to map earthquake effects immediately after the event prob- ably occurred in 1948. Since that time, the use of aerial photography has greatly facil- itated the compilation of post-earthquake landslide inventories, although because of the limitations of aerial photography, ground-based field studies continue to be cru- cial in preparing accurate and comprehensive landslide maps. Beginning with a small California earthquake in 1957

  15. Large landslides induced by the 2008 Wenchuan earthquake and their precursory gravitational slope deformation

    NASA Astrophysics Data System (ADS)

    Chigira, Masahiro; Wu, Xiyong; Wang, Gonghui; Uchida, Osamu

    2010-05-01

    2008 Wenchuan earthquake induced numerous large landslides, of which many large landslides had been preceded by gravitational deformation. The deformation could be detected by linear depressions and convex slopes observed on satellite images taken before the earthquake. Ground truth survey after the earthquake also found the gravitational deformation of rocks, which could be predated before the earthquake. The Daguanbao landslide, the largest landslide induced by this earthquake, occurred on a slope of bedded carbonate rocks. The area of the landslide, based on measurements made from the ALOS/PRISM images is 7.353 km2. Its volume is estimated to be 0.837 km3 based on the comparison of the PRISM data and the SRTM DEM. It had an open V-shaped main scarp, of which one linear part was along a high angle fault and the other was approximately parallel to the bedding strike. The upslope edge of the V-shaped main scarp was observed as 2- km long linear depressions along the ridge-top on satellite image before the landslide. This indicates that this slope had been already destabilized and small movement occurred along the bedding planes and along the fault before the event. The Wenchuan earthquake pulled the final trigger of this landslide. The major sliding surface was along the bedding plane, which was observed to dip 35° or slightly gentler. It was warped convex upward and the beds were fractured, which suggests that the beds were slightly buckled before the landslide. This deformation may correspond to the formation of the linear depression. The Tangjiashan landslide in Beichuan, which produced the largest landslide dam during the earthquake, occurred on a dip slope of shale and slate. The geologic structures of the landslide was observed on the side flanks of the landslide, which indicated that the beds had been buckled gravitationally beforehand and the sliding surface was made along the bedding plane and a joint parallel to the slope surface. The buckling

  16. Statiscal analysis of an earthquake-induced landslide distribution - The 1989 Loma Prieta, California event

    Keefer, D.K.

    2000-01-01

    The 1989 Loma Prieta, California earthquake (moment magnitude, M=6.9) generated landslides throughout an area of about 15,000 km2 in central California. Most of these landslides occurred in an area of about 2000 km2 in the mountainous terrain around the epicenter, where they were mapped during field investigations immediately following the earthquake. The distribution of these landslides is investigated statistically, using regression and one-way analysisof variance (ANOVA) techniques to determine how the occurrence of landslides correlates with distance from the earthquake source, slope steepness, and rock type. The landslide concentration (defined as the number of landslide sources per unit area) has a strong inverse correlation with distance from the earthquake source and a strong positive correlation with slope steepness. The landslide concentration differs substantially among the various geologic units in the area. The differences correlate to some degree with differences in lithology and degree of induration, but this correlation is less clear, suggesting a more complex relationship between landslide occurrence and rock properties. ?? 2000 Elsevier Science B.V. All rights reserved.

  17. Failure of a massive earthquake-induced landslide dam in Papua New Guinea

    King, J. P.; Loveday, I. C.; Schuster, R.L.

    1987-01-01

    This article discusses the recent occurrence of a large earthquake-induced landslide that dammed the Bairaman River in the interior of hte island of New Britian, Papua New Guinea, and the subsequent overtopping and failure of this landslide dam. 

  18. Extraordinary distance limits of landslides triggered by the 2011 Mineral, Virginia, earthquake

    Jibson, Randall W.; Harp, Edwin L.

    2012-01-01

    The 23 August 2011 Mineral, Virginia, earthquake (Mw 5.8) was the largest to strike the eastern U.S. since 1897 and was felt over an extraordinarily large area. Although no large landslides occurred, the shaking did trigger many rock and soil falls from steep river banks and natural cliffs in the epicentral area and from steep road cuts along, and northwest of, the Blue Ridge Parkway. We mapped the occurrence of rock falls to determine distance limits that could be compared with those from other documented earthquakes. Studies of previous earthquakes indicated a maximum epicentral distance limit for landsliding of ~60  km for an M 5.8 earthquake; the maximum distance limit for the 2011 earthquake was 245 km, the largest exceedance of the historical limit ever recorded. Likewise, the previous maximum area affected by landslides for this magnitude was 1500  km2; the area affected by landslides in the 2011 earthquake was 33,400  km2. These observations provide physical evidence that attenuation of strong shaking for eastern U.S. earthquakes is significantly lower than for plate‐boundary earthquakes. Also, distance limits parallel to the regional structural trend are greater than those that transect the structure, which suggests anisotropic attenuation related to the regional geologic structure. Peak ground acceleration (PGA) at the landslide distance limits is estimated to have been about 0.02–0.04g.

  19. Very-long-period volcanic earthquakes beneath Mammoth Mountain, California

    Hill, D.P.; Dawson, P.; Johnston, M.J.S.; Pitt, A.M.; Biasi, G.; Smith, K.

    2002-01-01

    Detection of three very-long-period (VLP) volcanic earthquakes beneath Mammoth Mountain emphasizes that magmatic processes continue to be active beneath this young, eastern California volcano. These VLP earthquakes, which occured in October 1996 and July and August 2000, appear as bell-shaped pulses with durations of one to two minutes on a nearby borehole dilatometer and on the displacement seismogram from a nearby broadband seismometer. They are accompanied by rapid-fire sequences of high-frequency (HF) earthquakes and several long- period (LP) volcanic earthquakes. The limited VLP data are consistent with a CLVD source at a depth of ???3 km beneath the summit, which we interpret as resulting from a slug of fluid (CO2- saturated magmatic brine or perhaps basaltic magma) moving into a crack.

  20. Can earthquake fissures predispose hillslopes to landslides? - Evidence from Central and East Asia

    NASA Astrophysics Data System (ADS)

    Sidle, Roy C.; Gomi, Takashi; Rajapbaev, Muslim; Chyngozhoev, Nurstan

    2017-04-01

    Factors affecting earthquake-initiated landslides include earthquake magnitude, focal depth, and seismic wave propagation and attenuation. In contrast to rainfall-initiated landslides, earthquake-induced landslides often occur on convex slopes and near ridgelines. Here we present evidence from Fergana Basin, Kyrgyzstan and Kumamoto, Japan on how fissures developed during earthquakes may promote subsequent initiation of rainfall-triggered landslides. More than 1800 recent major landslides in hilly terrain and soft sediments of the Fergana Basin have been largely attributed to accumulation of heavy rainfall and snowmelt. While no large earthquakes have occurred in the Fergana Basin, smaller earthquakes have generated fissures near ridgelines and on convex slopes. The connection of fissures, developed years or decades before slope failure, with preferential transport of rainwater and runoff into the soil has not been previously investigated. Fissures have been observed to expand with time, particularly during subsequent minor earthquakes, further promoting preferential infiltration. Because the soil mantle does not have large contrasts in permeability that would define a slip plane for landslides, it appears that the position and depth of these fissures may control the location and depth of failures. Zones in the soil where surficial inputs of water are preferentially transported, augment natural subsurface accumulation of antecedent rainfall. Many landslides in the eastern Fergana Basin occur after several months of accumulated precipitation and groundwater has been observed emerging on critical hillside locations (near ridgelines and on convex slopes) prior to slope failure. During the 2016 Kumamoto Earthquake (M 7.3), many landslides were triggered in forest and grassland hillslopes near Mount Aso. All of these earthquakes were shallow (focal depths about 10 km), causing high shaking intensity and ground rupturing. Because soils were relatively dry during these

  1. Landslides triggered by the Minxian-Zhangxian, China, Mw 5.9 earthquake of 22 July 2013

    NASA Astrophysics Data System (ADS)

    Xu, Chong; Xu, Xiwei; Shyu, J. Bruce H.

    2014-05-01

    On July 22, 2013, an earthquake of Ms 6.6 occurred at the junction area of Minxian and Zhangxian counties, Gansu Province, China. This earthquake triggered many landslides of various types, dominated by small-scale soil falls, slides, and topples on loess scarps. There were also some deep-seated landslides, large-scale soil avalanches, and fissure-developing slopes. In this paper, an inventory of landslides triggered by this event is prepared based on field investigations and visual interpretation of high-resolution satellite images. The spatial distribution of the landslides is then analyzed. The inventory indicates that at least 2,330 landslides were triggered by the earthquake. A correlation statistics of the landslides with topographic, geologic, and earthquake factors is performed based on the GIS platform. The results show that the largest number of landslides and the highest landslide density are at 2,400m-2,600m of absolute elevation, and 200m-300m of relative elevation, respectively. The landslide density does not always increase with slope gradient as previously suggested. The slopes most prone to landslides are in S, SW, W, and NW directions. Concave slopes register higher landslide density and larger number of landslides than convex slopes. The largest number of landslides occurs on topographic position with middle slopes, whereas the highest landslide density corresponds to valleys and lower slopes. The underlying bedrocks consisting of conglomerate and sandstone of Lower Paleogene (Eb) register both the largest number of landslides and the highest landslide density value. There is no clear relationship between PGA and the co-seismic landslides. Correlations of landslide number and landslide density with perpendicular- and along-strike distance from the epicenter show an obvious spatial intensifying character of the co-seismic landslides. The spatial pattern of the co-seismic landslides is strongly controlled by a branch of the Lintan-Dangchang fault

  2. Regional Triggering of Volcanic Activity Following Large Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Hill-Butler, Charley; Blackett, Matthew; Wright, Robert

    2015-04-01

    There are numerous reports of a spatial and temporal link between volcanic activity and high magnitude seismic events. In fact, since 1950, all large magnitude earthquakes have been followed by volcanic eruptions in the following year - 1952 Kamchatka M9.2, 1960 Chile M9.5, 1964 Alaska M9.2, 2004 & 2005 Sumatra-Andaman M9.3 & M8.7 and 2011 Japan M9.0. While at a global scale, 56% of all large earthquakes (M≥8.0) in the 21st century were followed by increases in thermal activity. The most significant change in volcanic activity occurred between December 2004 and April 2005 following the M9.1 December 2004 earthquake after which new eruptions were detected at 10 volcanoes and global volcanic flux doubled over 52 days (Hill-Butler et al. 2014). The ability to determine a volcano's activity or 'response', however, has resulted in a number of disparities with <50% of all volcanoes being monitored by ground-based instruments. The advent of satellite remote sensing for volcanology has, therefore, provided researchers with an opportunity to quantify the timing, magnitude and character of volcanic events. Using data acquired from the MODVOLC algorithm, this research examines a globally comparable database of satellite-derived radiant flux alongside USGS NEIC data to identify changes in volcanic activity following an earthquake, February 2000 - December 2012. Using an estimate of background temperature obtained from the MODIS Land Surface Temperature (LST) product (Wright et al. 2014), thermal radiance was converted to radiant flux following the method of Kaufman et al. (1998). The resulting heat flux inventory was then compared to all seismic events (M≥6.0) within 1000 km of each volcano to evaluate if changes in volcanic heat flux correlate with regional earthquakes. This presentation will first identify relationships at the temporal and spatial scale, more complex relationships obtained by machine learning algorithms will then be examined to establish favourable

  3. Landslides triggered by the January 12, 2010 Port-au-Prince, Haiti Mw 7.0 earthquake

    NASA Astrophysics Data System (ADS)

    Xu, Chong

    2014-05-01

    The January 12, 2010 Port-au-Prince, Haiti earthquake (Mw 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate correlations of the occurrence of landslides and its erosion thickness with topographic factors, seismic parameters, and distance from roads. A total of 30,828 landslides triggered by the earthquake cover a total area of 15.736 km2, and the volume of landslide accumulation materials is estimated to be about 30,000,000 m3, and throughout an area more than 3,000 km2. These landslides are of various types, mainly in shallow disrupted landslides and rock falls, and also including coherent deep-seated landslides, shallow disrupted landslides, rock falls, and rock slides. These landslides were delineated using pre- and post-earthquake high-resolutions satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were respectively constructed in order to more intuitive to discover the spatial distribution patterns of the co-seismic landslides. Statistics of size distribution and morphometric parameters of the co-seismic landslides were carried out and were compared with other earthquake events. Four proxies of co-seismic landslides abundances, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate the co-seismic landslides with various landslide controlling parameters. These controlling parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, stratum/lithology, distance from the epicenter, distance from the Enriquillo-Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). Comparing of controls of impact parameters on co-seismic landslides show that slope angle is the strongest impact parameter on co-seismic landslides

  4. Preliminary investigation of some large landslides triggered by the 2008 Wenchuan earthquake, Sichuan Province, China

    Wang, F.; Cheng, Q.; Highland, L.; Miyajima, M.; Wang, Hongfang; Yan, C.

    2009-01-01

    The M s 8.0 Wenchuan earthquake or "Great Sichuan Earthquake" occurred at 14:28 p.m. local time on 12 May 2008 in Sichuan Province, China. Damage by earthquake-induced landslides was an important part of the total earthquake damage. This report presents preliminary observations on the Hongyan Resort slide located southwest of the main epicenter, shallow mountain surface failures in Xuankou village of Yingxiu Town, the Jiufengchun slide near Longmenshan Town, the Hongsong Hydro-power Station slide near Hongbai Town, the Xiaojiaqiao slide in Chaping Town, two landslides in Beichuan County-town which destroyed a large part of the town, and the Donghekou and Shibangou slides in Qingchuan County which formed the second biggest landslide lake formed in this earthquake. The influences of seismic, topographic, geologic, and hydro-geologic conditions are discussed. ?? 2009 Springer-Verlag.

  5. Landslides Triggered by the 12 May 2008, M 7.9 Wenchuan, China Earthquake

    NASA Astrophysics Data System (ADS)

    Harp, E.; Jibson, R.; Godt, J.

    2009-04-01

    The 12 May 2008, M 7.9 Wenchuan earthquake in eastern Sichuan Province of China triggered tens of thousands of rock falls, rock slides, rock avalanches, and deep, complex, landslides. Of the approximately 87,000 deaths caused by the earthquake, more than 20,000 have been attributed to landsides. Numerous villages were buried by large landslides. Air-blasts resulting from the rapid failure and movement of landslides were observed and documented from numerous eye-witness accounts. More than 100 landslide-dammed lakes were created by the earthquake, 33 of which were evaluated to determine if spillway construction was necessary to minimize flooding by future breaching of the landslide dams. Spillways were ultimately constructed on at least 16 landslide dams. Preliminary observations in the field and from satellite imagery indicate that the most common types of landslides were rock falls and rock slides that ranged in size from several hundred cubic meters to several hundred thousand cubic meters in volume. There were hundreds to perhaps as many as one thousand landslides exceeding 1 million cubic meters in volume. The largest landslide identified using Jaxa's Alos/Prism satellite imagery (2.5 m resolution) is nearly 1 billion cubic meters in volume and is located approximately 12 km north-northeast of the city of Hanwang. This landslide appears to have resulted from the failure of a 1.5-km section of ridge crest that now occupies most of the adjacent valley to the northeast; its toe spills over the next ridge crest to the northeast. The satellite imagery of 4 June 2008 shows two small lakes dammed by the slide debris. Within the mountainous areas in the near-field zone of shaking, rock slides dammed chains of lakes in many drainages. Sections of streams 2-3 km long have been completely covered by rock debris as of the 4 June imagery The debris from the triggered landslides is being redistributed rapidly by post-earthquake rainfall. A 100-year rainstorm in September

  6. Distinguishing high surf from volcanic long-period earthquakes

    Lyons, John; Haney, Matt; Fee, David; Paskievitch, John F.

    2014-01-01

    Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12–14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

  7. Correlation between hypocenter depth, antecedent precipitation and earthquake-induced landslide spatial distribution

    NASA Astrophysics Data System (ADS)

    Fukuoka, Hiroshi; Watanabe, Eisuke

    2017-04-01

    Since Keefer published the paper on earthquake magnitude and affected area, maximum epicentral/fault distance of induced landslide distribution in 1984, showing the envelope of plots, a lot of studies on this topic have been conducted. It has been generally supposed that landslides have been triggered by shallow quakes and more landslides are likely to occur with heavy rainfalls immediately before the quake. In order to confirm this, we have collected 22 case records of earthquake-induced landslide distribution in Japan and examined the effect of hypocenter depth and antecedent precipitation. Earthquake magnitude by JMA (Japan Meteorological Agency) of the cases are from 4.5 to 9.0. Analysis on hycpocenter depth showed the deeper quake cause wider distribution. Antecedent precipitation was evaluated using the Soil Water Index (SWI), which was developed by JMA for issuing landslide alert. We could not find meaningful correlation between SWI and the earthquake-induced landslide distribution. Additionally, we found that smaller minimum size of collected landslides results in wider distribution especially between 1,000 to 100,000 m2.

  8. Landslides and dam damage resulting from the Jiuzhaigou earthquake (8 August 2017), Sichuan, China

    PubMed Central

    Wang, Yun-sheng; Luo, Yong-hong; Li, Jia; Zhang, Xin; Shen, Tong

    2018-01-01

    At 21.19 on 8 August 2017, an Ms 7.0 earthquake struck the Jiuzhaigou scenic spot in northwestern Sichuan Province, China. The Jiuzhaigou earthquake is a strike-slip earthquake with a focal depth of 20 km at 33.20° N and 103.82° E, and was caused by two concealed faults. According to emergency investigations and remote sensing interpretations, the Jiuzhaigou earthquake triggered 1780 landslides, damaged one dam (Nuorilang Waterfall) and broke one dam (Huohua Lake). The landslides mainly occurred in the Rize Valley and Shuzheng Valley and in Jiuzhai Paradise. The landslides involved hanging wall and back-slope effects, and the slope angle, slope aspect, seismic faults and valley trend were obviously related to the occurrence of the landslides. Specifically, most of the landslides were shallow landslides, rockfalls and rock avalanches and were small in scale. The failure modes of landslides mainly include wedge rock mass failure, residual deposit failure, relaxed rock mass failure and weathered rock mass failure. The initial low stability of the dam coupled with the topographic effect, back-slope effect and excess pore water pressure led to damage to the Nuorilang Waterfall dam. PMID:29657755

  9. Landslides and dam damage resulting from the Jiuzhaigou earthquake (8 August 2017), Sichuan, China

    NASA Astrophysics Data System (ADS)

    Zhao, Bo; Wang, Yun-sheng; Luo, Yong-hong; Li, Jia; Zhang, Xin; Shen, Tong

    2018-03-01

    At 21.19 on 8 August 2017, an Ms 7.0 earthquake struck the Jiuzhaigou scenic spot in northwestern Sichuan Province, China. The Jiuzhaigou earthquake is a strike-slip earthquake with a focal depth of 20 km at 33.20° N and 103.82° E, and was caused by two concealed faults. According to emergency investigations and remote sensing interpretations, the Jiuzhaigou earthquake triggered 1780 landslides, damaged one dam (Nuorilang Waterfall) and broke one dam (Huohua Lake). The landslides mainly occurred in the Rize Valley and Shuzheng Valley and in Jiuzhai Paradise. The landslides involved hanging wall and back-slope effects, and the slope angle, slope aspect, seismic faults and valley trend were obviously related to the occurrence of the landslides. Specifically, most of the landslides were shallow landslides, rockfalls and rock avalanches and were small in scale. The failure modes of landslides mainly include wedge rock mass failure, residual deposit failure, relaxed rock mass failure and weathered rock mass failure. The initial low stability of the dam coupled with the topographic effect, back-slope effect and excess pore water pressure led to damage to the Nuorilang Waterfall dam.

  10. Landslides and dam damage resulting from the Jiuzhaigou earthquake (8 August 2017), Sichuan, China.

    PubMed

    Zhao, Bo; Wang, Yun-Sheng; Luo, Yong-Hong; Li, Jia; Zhang, Xin; Shen, Tong

    2018-03-01

    At 21.19 on 8 August 2017, an Ms 7.0 earthquake struck the Jiuzhaigou scenic spot in northwestern Sichuan Province, China. The Jiuzhaigou earthquake is a strike-slip earthquake with a focal depth of 20 km at 33.20° N and 103.82° E, and was caused by two concealed faults. According to emergency investigations and remote sensing interpretations, the Jiuzhaigou earthquake triggered 1780 landslides, damaged one dam (Nuorilang Waterfall) and broke one dam (Huohua Lake). The landslides mainly occurred in the Rize Valley and Shuzheng Valley and in Jiuzhai Paradise. The landslides involved hanging wall and back-slope effects, and the slope angle, slope aspect, seismic faults and valley trend were obviously related to the occurrence of the landslides. Specifically, most of the landslides were shallow landslides, rockfalls and rock avalanches and were small in scale. The failure modes of landslides mainly include wedge rock mass failure, residual deposit failure, relaxed rock mass failure and weathered rock mass failure. The initial low stability of the dam coupled with the topographic effect, back-slope effect and excess pore water pressure led to damage to the Nuorilang Waterfall dam.

  11. Steam explosions, earthquakes, and volcanic eruptions -- what's in Yellowstone's future?

    Lowenstern, Jacob B.; Christiansen, Robert L.; Smith, Robert B.; Morgan, Lisa A.; Heasler, Henry

    2005-01-01

    Yellowstone, one of the world?s largest active volcanic systems, has produced several giant volcanic eruptions in the past few million years, as well as many smaller eruptions and steam explosions. Although no eruptions of lava or volcanic ash have occurred for many thousands of years, future eruptions are likely. In the next few hundred years, hazards will most probably be limited to ongoing geyser and hot-spring activity, occasional steam explosions, and moderate to large earthquakes. To better understand Yellowstone?s volcano and earthquake hazards and to help protect the public, the U.S. Geological Survey, the University of Utah, and Yellowstone National Park formed the Yellowstone Volcano Observatory, which continuously monitors activity in the region.

  12. Spatial distribution of landslides triggered from the 2007 Niigata Chuetsu–Oki Japan Earthquake

    Collins, Brian D.; Kayen, Robert E.; Tanaka, Yasuo

    2012-01-01

    Understanding the spatial distribution of earthquake-induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events. The July 16, 2007 Mw 6.6 (MJMA 6.8) Niigata Chuetsu–Oki Japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of Kashiwazaki and provides one such opportunity to evaluate the impacts of an offshore, magnitude 6 + earthquake on a steep coastal region. As part of a larger effort to document all forms of geotechnical damage from this earthquake, we performed landslide inventory mapping throughout the epicentral area and analyzed the resulting data for spatial, seismic-motion, and geologic correlations to describe the pattern of landsliding. Coupled with examination of a third-party, aerial-photo-based landslide inventory, our analyses reveal several areas of high landslide concentration that are not readily explained by either traditional epicentral and fault–plane-distance metrics or by recorded and inferred ground-motions. Whereas average landslide concentrations averaged less than 1 landslide per square kilometer (LS/km2), some areas reached up to 2 LS/km2 in the Nishiyama Hills to the northeast of Kashiwazaki and between 2 and 11 LS/km2 in coastal areas to the north and south of the city. Correlation with seismometer-based and monument overturning back-calculated ground motions suggests that a minimum peak ground acceleration (PGA) of approximately 0.2 g was necessary for landsliding throughout the region, but does not explain the subregional areas of high landslide concentration. However, analysis of topographic slope and the distribution of generally weak, dip-slope, geologic units does sufficiently explain why, on a sub-regional scale, high landslide concentrations occurred where they did. These include: (1) an inland region of steep, dip-slope, anticlinal sedimentary strata with associated fold belt compression and uplift of the anticline and (2

  13. Specific signature of seismic shaking in landslide catalogues: Case of the Chichi earthquake

    NASA Astrophysics Data System (ADS)

    Meunier, Patrick; Rault, Claire; Marc, Odin; Hovius, Niels

    2017-04-01

    The 1999 Chichi earthquake triggered 10 000 landslides in its epicentral area. In addition to coseismic landsliding, directly induced by the shaking, the hillslopes response extended to several years after the main shock, during which landslide susceptibility remained higher than during the pre-seismic period. We attribute this elevated rate to weakening effects caused by the shaking. The characteristics of the coseismic landslide catalogues (clustering, slope and azimuth distribution) bears the signature of the seismic triggering. Extended landslide mapping (1994-2004) allows to track changes in these signatures in order to better interpret them. We present a summary of the change of these signatures through time and space. At the scale of the epicentral area, we show that coseismic landslide clustering did clearly occur along the fault where the shaking is strong. In 3 sub-catchments of the Choshui river, a finer analysis of the landslide time series reveals a mixed signature of both geology and shaking. Pre-quake rain-induced landslides preferentially occurred down slope and along the bedding planes while coseismic landslides locate higher in the landscape, on slopes strongly affected by site effects. However, during the post seismic period, the signature of the shaking is not present while landslide rate remains high, suggesting that weakening effects seemed homogeneously distributed in the landscape.

  14. Specific Signature of Seismic Shaking in Landslide Inventories: Case of the Chichi Earthquake

    NASA Astrophysics Data System (ADS)

    Meunier, P.; Rault, C.; Marc, O.; Hovius, N.

    2017-12-01

    The 1999 Chichi earthquake triggered 10 000 landslides in its epicentral area. In addition to coseismic landsliding, directly induced by the shaking, the hillslopes response extended to several years after the main shock, during which landslide susceptibility remained higher than during the pre-seismic period. We attribute this elevated rate to weakening effects caused by the shaking. The characteristics of the coseismic landslide catalogues (clustering,slope and azimuth distribution) bears the signature of the seismic triggering. Extended landslide mapping (1994-2004) allows to track changes in these signatures in order to better interpret them. We present a summary of the change of these signatures through time and space. At the scale of the epicentral area, we show that coseismic landslide clustering did clearly occur along the fault where the shaking is strong. In 3 sub-catchments of the Choshui river, a finer analysis of the landslide time series reveals a mixed signature of both geology and shaking. Pre-quake rain-induced landslides preferentially occurred down slope and along the bedding planes while coseismic landslides locate higher in the landscape, on slopes strongly affected by site effects. However, during the post seismic period, the signature of the shaking is not present while landslide rate remains high, suggesting that weakening effects seemed homogeneously distributed in the landscape.

  15. Landscape scale prediction of earthquake-induced landsliding based on seismological and geomorphological parameters.

    NASA Astrophysics Data System (ADS)

    Marc, O.; Hovius, N.; Meunier, P.; Rault, C.

    2017-12-01

    In tectonically active areas, earthquakes are an important trigger of landslides with significant impact on hillslopes and river evolutions. However, detailed prediction of landslides locations and properties for a given earthquakes remain difficult.In contrast we propose, landscape scale, analytical prediction of bulk coseismic landsliding, that is total landslide area and volume (Marc et al., 2016a) as well as the regional area within which most landslide must distribute (Marc et al., 2017). The prediction is based on a limited number of seismological (seismic moment, source depth) and geomorphological (landscape steepness, threshold acceleration) parameters, and therefore could be implemented in landscape evolution model aiming at engaging with erosion dynamics at the scale of the seismic cycle. To assess the model we have compiled and normalized estimates of total landslide volume, total landslide area and regional area affected by landslides for 40, 17 and 83 earthquakes, respectively. We have found that low landscape steepness systematically leads to overprediction of the total area and volume of landslides. When this effect is accounted for, the model is able to predict within a factor of 2 the landslide areas and associated volumes for about 70% of the cases in our databases. The prediction of regional area affected do not require a calibration for the landscape steepness and gives a prediction within a factor of 2 for 60% of the database. For 7 out of 10 comprehensive inventories we show that our prediction compares well with the smallest region around the fault containing 95% of the total landslide area. This is a significant improvement on a previously published empirical expression based only on earthquake moment.Some of the outliers seems related to exceptional rock mass strength in the epicentral area or shaking duration and other seismic source complexities ignored by the model. Applications include prediction on the mass balance of earthquakes and

  16. Geological, Geophysical, and Stochastic Factors in Nepal's Gorkha Earthquake-Triggered Landslide Distribution

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Shugar, D. H.; Haritashya, U. K.; Leonard, G. J.; Fielding, E. J.; Hudnut, K. W.; Jibson, R.; Collins, B. D.

    2015-12-01

    On 25 April 2015, a magnitude 7.8 earthquake struck Nepal. Subsequently many large aftershocks shook the region, including one of magnitude 7.3. Much damage and over 4300 landslides were triggered. The landslides were mapped by a volunteer group who self organized to undertake an emergency response to the earthquake disaster. The number of landslides is fewer than expected based on total released seismic energy. This may be because of lack of a surface rupture and possibly also because of high surface-wave attenuation due to rugged surface topography or to the geological and geophysical characteristics of the upper crust. The observed landslides were primarily in the southern half of the Himalaya in areas where the steepest slopes occur and where peak ground accelerations were relatively high. The landslides are also concentrated on the tectonically downdropped block. However, the distribution is complex and varies dramatically from valley to valley. Furthermore, different types of landslides are concentrated in different geologic materials, which suggests local factors control the valley-scale attenuation or amplification of seismic waves or the way wave disturbances couple to the local geologic materials. Across the earthquake-affected zone on the regional scale, wave attenuation and also net downdrop and uplift may also explain as much about the distribution of landslides as slopes and distance from large slips on the fault. We will offer the regional distribution results and some specific case studies to illustrate a set of possible controlling factors.

  17. Prediction of the area affected by earthquake-induced landsliding based on seismological parameters

    NASA Astrophysics Data System (ADS)

    Marc, Odin; Meunier, Patrick; Hovius, Niels

    2017-07-01

    We present an analytical, seismologically consistent expression for the surface area of the region within which most landslides triggered by an earthquake are located (landslide distribution area). This expression is based on scaling laws relating seismic moment, source depth, and focal mechanism with ground shaking and fault rupture length and assumes a globally constant threshold of acceleration for onset of systematic mass wasting. The seismological assumptions are identical to those recently used to propose a seismologically consistent expression for the total volume and area of landslides triggered by an earthquake. To test the accuracy of the model we gathered geophysical information and estimates of the landslide distribution area for 83 earthquakes. To reduce uncertainties and inconsistencies in the estimation of the landslide distribution area, we propose an objective definition based on the shortest distance from the seismic wave emission line containing 95 % of the total landslide area. Without any empirical calibration the model explains 56 % of the variance in our dataset, and predicts 35 to 49 out of 83 cases within a factor of 2, depending on how we account for uncertainties on the seismic source depth. For most cases with comprehensive landslide inventories we show that our prediction compares well with the smallest region around the fault containing 95 % of the total landslide area. Aspects ignored by the model that could explain the residuals include local variations of the threshold of acceleration and processes modulating the surface ground shaking, such as the distribution of seismic energy release on the fault plane, the dynamic stress drop, and rupture directivity. Nevertheless, its simplicity and first-order accuracy suggest that the model can yield plausible and useful estimates of the landslide distribution area in near-real time, with earthquake parameters issued by standard detection routines.

  18. Volcanic conduit migration over a basement landslide at Mount Etna (Italy)

    PubMed Central

    Nicolosi, I.; Caracciolo, F. D'Ajello; Branca, S.; Ventura, G.; Chiappini, M.

    2014-01-01

    The flanks of volcanoes may slide in response to the loading of the edifice on a weak basement, magma push, and/or to tectonic stress. However, examples of stratovolcanoes emplaced on active landslides are lacking and the possible effects on the volcano dynamics unknown. Here, we use aeromagnetic data to construct a three-dimensional model of the clay-rich basement of Etna volcano (Italy). We provide evidence for a large stratovolcano growing on a pre-existing basement landslide and show that the eastern Etna flank, which slides toward the sea irrespective of volcanic activity, moves coherently with the underlying landslide. The filling of the landslide depression by lava flows through time allows the formation of a stiffness barrier, which is responsible for the long-term migration of the magma pathways from the coast to the present-day Etna summit. These unexpected results provide a new interpretation clue on the causes of the volcanic instability processes and of the mechanisms of deflection and migration of volcanic conduits. PMID:24924784

  19. Volcanic conduit migration over a basement landslide at Mount Etna (Italy).

    PubMed

    Nicolosi, I; Caracciolo, F D'Ajello; Branca, S; Ventura, G; Chiappini, M

    2014-06-13

    The flanks of volcanoes may slide in response to the loading of the edifice on a weak basement, magma push, and/or to tectonic stress. However, examples of stratovolcanoes emplaced on active landslides are lacking and the possible effects on the volcano dynamics unknown. Here, we use aeromagnetic data to construct a three-dimensional model of the clay-rich basement of Etna volcano (Italy). We provide evidence for a large stratovolcano growing on a pre-existing basement landslide and show that the eastern Etna flank, which slides toward the sea irrespective of volcanic activity, moves coherently with the underlying landslide. The filling of the landslide depression by lava flows through time allows the formation of a stiffness barrier, which is responsible for the long-term migration of the magma pathways from the coast to the present-day Etna summit. These unexpected results provide a new interpretation clue on the causes of the volcanic instability processes and of the mechanisms of deflection and migration of volcanic conduits.

  20. A seismic landslide susceptibility rating of geologic units based on analysis of characterstics of landslides triggered by the 17 January, 1994 Northridge, California earthquake

    Parise, M.; Jibson, R.W.

    2000-01-01

    One of the most significant effects of the 17 January, 1994 Northridge, California earthquake (M=6.7) was the triggering of thousands of landslides over a broad area. Some of these landslides damaged and destroyed homes and other tructures, blocked roads, disrupted pipelines, and caused other serious damage. Analysis of the distribution and characteristics of these landslides is important in understanding what areas may be susceptible to landsliding in future earthquakes. We analyzed the frequency, distribution, and geometries of triggered landslides in the Santa Susana 7.5??? quadrangle, an area of intense seismic landslide activity near the earthquake epicenter. Landslides occured primarily in young (Late Miocene through Pleistocene) uncemented or very weakly cemented sediment that has been repeatedly folded, faulted, and uplifted in the past 1.5 million years. The most common types of landslide triggered by the earthquake were highly disrupted, shallow falls and slides of rock and debris. Far less numerous were deeper, more coherent slumps and block slides, primarily occuring in more cohesive or competent materials. The landslides in the Santa Susana quadrangle were divided into two samples: single landslides (1502) and landslide complexes (60), which involved multiple coalescing failures of surficial material. We described landslide, morphologies by computing simple morphometric parameters (area, length, width, aspect ratio, slope angle). To quantify and rank the relative susceptibility of each geologic unit to seismic landsliding, we calculated two indices: (1) the susceptibility index, which is the ratio (given as a percentage) of the area covered by landslide sources within a geologic unit to the total outcrop area of that unit: and (2) the frequency index [given in landslides per square kilometer (ls/km2)], which is the total number of landslides within each geologic unit divided by the outcrop area of that unit. Susceptibility categories include very high

  1. Landslide maps and seismic noise: Rockmass weakening caused by shallow earthquakes

    NASA Astrophysics Data System (ADS)

    Uchida, Tara; Marc, Odin; Sens-Schönfelder, Christoph; Sawazaki, Kaoru; Hobiger, Manuel; Hovius, Niels

    2015-04-01

    Some studies have suggested that the shaking and deformation associated with earthquake would result in a temporary increased hillslope erodibility. However very few data have been able to clarify such effect. We present integrated geomorphic data constraining an elevated landslide rate following 4 continental shallow earthquakes, the Mw 6.9 Finisterre (1993), the Mw 7.6 ChiChi (1999), the Mw 6.6 Niigata (2004) and the Mw 6.8 Iwate-Miyagi (2008) earthquakes. We constrained the magnitude, the recovery time and somewhat the mechanism at the source of this higher landslide risk. We provide some evidences excluding aftershocks or rain forcing intensity as possible mechanism and leaving subsurface weakening as the most likely. The landslide data suggest that this ground strength weakening is not limited to the soil cover but also affect the shallow bedrock. Additionally, we used ambient noise autocorrelation techniques to monitor shallow subsurface seismic velocity within the epicentral area of three of those earthquakes. For most stations we observe a velocity drop followed by a recovery processes of several years in fair agreement with the recovery time estimated based on landslide observation. Thus a common processes could alter the strength of the first 10m of soil/rock and simultaneously drive the landslide rate increase and the seismic velocity drop. The ability to firmly demonstrate this link require additional constraints on the seismic signal interpretation but would provide a very useful tool for post-earthquake risk managment.

  2. Possible worst-case tsunami scenarios around the Marmara Sea from combined earthquake and landslide sources

    NASA Astrophysics Data System (ADS)

    Latcharote, Panon; Suppasri, Anawat; Imamura, Fumihiko; Aytore, Betul; Yalciner, Ahmet Cevdet

    2016-12-01

    This study evaluates tsunami hazards in the Marmara Sea from possible worst-case tsunami scenarios that are from submarine earthquakes and landslides. In terms of fault-generated tsunamis, seismic ruptures can propagate along the North Anatolian Fault (NAF), which has produced historical tsunamis in the Marmara Sea. Based on the past studies, which consider fault-generated tsunamis and landslide-generated tsunamis individually, future scenarios are expected to generate tsunamis, and submarine landslides could be triggered by seismic motion. In addition to these past studies, numerical modeling has been applied to tsunami generation and propagation from combined earthquake and landslide sources. In this study, tsunami hazards are evaluated from both individual and combined cases of submarine earthquakes and landslides through numerical tsunami simulations with a grid size of 90 m for bathymetry and topography data for the entire Marmara Sea region and validated with historical observations from the 1509 and 1894 earthquakes. This study implements TUNAMI model with a two-layer model to conduct numerical tsunami simulations, and the numerical results show that the maximum tsunami height could reach 4.0 m along Istanbul shores for a full submarine rupture of the NAF, with a fault slip of 5.0 m in the eastern and western basins of the Marmara Sea. The maximum tsunami height for landslide-generated tsunamis from small, medium, and large of initial landslide volumes (0.15, 0.6, and 1.5 km3, respectively) could reach 3.5, 6.0, and 8.0 m, respectively, along Istanbul shores. Possible tsunamis from submarine landslides could be significantly higher than those from earthquakes, depending on the landslide volume significantly. These combined earthquake and landslide sources only result in higher tsunami amplitudes for small volumes significantly because of amplification within the same tsunami amplitude scale (3.0-4.0 m). Waveforms from all the coasts around the Marmara Sea

  3. Coseismic landsliding associated with the 2015 April 25th Gorkha earthquake, Nepal

    NASA Astrophysics Data System (ADS)

    Clark, Marin; Zekkos, Dimitrios; West, A. Joshua; Gallen, Sean; Roback, Kevin; Chamlagain, Deepak; Athanasopoulos-Zekkos, Adda; Greenwood, William; Bateman, Julie; Partenio, Michael; Li, Gen; Cook, Kristen; Godt, Jonathan; Howat, Ian; Morin, Paul

    2016-04-01

    The characteristics of earthquake-triggered landslides have the potential to inform us about the ground motions during large earthquakes and the rock properties of the near surface environment. From the recent Mw7.8 2015 Gorkha earthquake in Nepal, we use satellite imagery to identify over 20,000 landslides that are associated with the main shock. While most landslides are located on steep hillslopes, we also present field measurements of alluvial terraces that have either failed or remained stable during the earthquake. We show how both hillslope and terrace failures can be used to better understand the earthquake. These local, site-specific surveys and analyses of alluvial terraces can be used to constrain co-seismic peak ground acceleration (PGA) and large landslide inventories can be used to gain insight into regional patterns of strong ground motion. Our regional landslide mapping reveals two principal patterns: (1) landslides are concentrated in the steep Greater Himalaya in the north, with conspicuously fewer landslides in the moderately-steep Lesser Himalaya in the south, and (2) within the Greater Himalaya, landslide density increases from west to east across the rupture area. We have compared our observed map of landslide occurrence to predictions from forward models using hillslope angles, average rock strength, and PGA estimated from ground motion prediction equations (GMPE). The higher concentration of landslides in the Greater Himalaya compared to the Lesser Himalaya can be predicted by the models and explained by the steeper topography of the Greater Himalaya. However, these forward models do not reproduce the east to west variation in observed landslide density, which is lower than model predictions near the epicenter, and greater than model predictions toward the eastern limit of the rupture. From limit equilibrium stability analysis of both failed and stable fluvial terraces, we constrain local PGA values in the eastern region of dense landsliding

  4. Regional analysis of distribution of pre and post 2015 Nepal Earthquake landslides

    NASA Astrophysics Data System (ADS)

    Valagussa, Andrea; Frattini, Paolo; Crosta, Giovanni; Valbuzzi, Elena

    2016-04-01

    A magnitude 7.8 earthquake struck Nepal on April 25, 2015. Three landslide inventories have been prepared in four districts: Dhading (1885 km2), Sindhupalchok (2488 km2), Rasuwa (1522 km2) and Nuwakot (1194 km2), that are located north of Kathmandu. These inventories extend 14 to 138 km SE from the epicenter of the main shock (April 25, 2015), 4.5 to 143 km NW from the epicenter of the main aftershock (May 12, 2015), and 34 to 136 km from the Main Frontal Thrust. The first inventory is a coseismic and post-seismic landslide inventory based on multi-temporal images (Google Earth, Google Crisis maps, Bing maps), and helicopter-based video. The second one is a pre-event shallow landslide inventory. In these two inventories the most abundant landslide types are: debris flows, shallow translational slides, and rockfalls. The third is a deep seated landslide inventory, in which the most represented landslide types are rock avalanches, slumps, rockslides and deep-seated gravitational slope deformations (DSGSD). All the landslides have been mapped as individual polygons. For the analysis we focus our attention on four districts: First we studied how the landslide frequency density changes as a function of topographic parameters (i.e. slope gradient, slope aspect, and elevation). The analyses have been based on the ASTER Global Digital Elevation Model (ASTER GDEM). For coseismic and post-seismic landslides we observed that the mean slope gradient at which the landslide occurs is higher with respect to the two other inventories (50° and 30/40° respectively). The slope aspect of coseismic and post-seismic landslides is also different, with a larger frequency of landslides towards SW, whereas in pre-event landslides the most common slope aspect is SE. This could be related to the direction of the seismic wave. At least the coseismic and post-seismic landslides occur, in mean, at an elevation lower than the pre-event landslides. We also analyzed the relationship between the

  5. Development of a global slope dataset for estimation of landslide occurrence resulting from earthquakes

    Verdin, Kristine L.; Godt, Jonathan W.; Funk, Christopher C.; Pedreros, Diego; Worstell, Bruce; Verdin, James

    2007-01-01

    Landslides resulting from earthquakes can cause widespread loss of life and damage to critical infrastructure. The U.S. Geological Survey (USGS) has developed an alarm system, PAGER (Prompt Assessment of Global Earthquakes for Response), that aims to provide timely information to emergency relief organizations on the impact of earthquakes. Landslides are responsible for many of the damaging effects following large earthquakes in mountainous regions, and thus data defining the topographic relief and slope are critical to the PAGER system. A new global topographic dataset was developed to aid in rapidly estimating landslide potential following large earthquakes. We used the remotely-sensed elevation data collected as part of the Shuttle Radar Topography Mission (SRTM) to generate a slope dataset with nearly global coverage. Slopes from the SRTM data, computed at 3-arc-second resolution, were summarized at 30-arc-second resolution, along with statistics developed to describe the distribution of slope within each 30-arc-second pixel. Because there are many small areas lacking SRTM data and the northern limit of the SRTM mission was lat 60?N., statistical methods referencing other elevation data were used to fill the voids within the dataset and to extrapolate the data north of 60?. The dataset will be used in the PAGER system to rapidly assess the susceptibility of areas to landsliding following large earthquakes.

  6. Environmental impact of the landslides caused by the 12 May 2008, Wenchuan, China earthquake

    Highland, Lynn; Sun, Ping; Edited by Margottini, Claudio; Canuti, Paolo; Sassa, Kyoji

    2013-01-01

    The magnitude 7.9 (Mw) Wenchuan, China, earthquake of May 12, 2008 caused at least 88,000 deaths of which one third are estimated to be due to the more than 56,000 earthquake-induced landslides. The affected area is mountainous, featuring densely-vegetated, steep slopes through which narrowly confined rivers and streams flow. Numerous types of landslides occurred in the area, including rock avalanches, rock falls, translational and rotational slides, lateral spreads and debris flows. Some landslides mobilized hundreds of million cubic meters of material, often resulting in the damming of rivers and streams, impacting river ecosystems and morphology. Through an extensive search of both Chinese- and English-language publications we provide a summary of pertinent research on environmental effects, emphasizing key findings. Environmental effects caused by landslides include the alteration of agriculture, changes to natural ecosystems, changes in river morphology due to landslide dams and other effects such as sedimentation and flooding. Damage by landslides to the giant panda reserve infrastructure and habitat, was severe, threatening the survival of one of the world’s rarest species. The Panda reserves are of national significance to China, and to the vital tourism economy of the region. One of the major impacts to both the natural and built environment is the complete relocation of some human populations and infrastructure to new areas, resulting in the abandonment of towns and other areas that were damaged by the earthquake and landslides. The landslide effects have affected the biodiversity of the affected area, and it has been hypothesized that strict forest preservation measures taken in the years preceding the earthquake resulted in a reduction of the environmental damage to the area.

  7. Landslides triggered by earthquakes in the central Mississippi Valley, Tennessee and Kentucky

    Jibson, Randall W.; Keefer, David K.

    1988-01-01

    We mapped 221 large (more than 200 ft across) landslides of three morphologically distinct types on the bluffs bordering the Mississippi alluvial plain in western Tennessee and Kentucky Old coherent slides (146 landslides, or 66 percent of the total) include translational block slides and single and multiple-block rotational slumps, all of which are covered by mature vegetation and have eroded features; no active analogs exist in the area. Earth flows (51 landslides, or 23 percent of the total) are also largely revegetated and eroded, though a few active earth flows are present on bluffs that have been cleared of vegetation. Young rotational slumps (24 landslides, or 11 percent of the total) form solely along actively eroding near-river bluffs and are the only active or recently active landslides in the area. Two investigations conducted around 1900 indicate that the old coherent slides, in at least part of the area, formed during the 1811-12 earthquakes. The present investigation uses dendrochronology, geomorphology, historic topographic maps, local historical accounts, and comparisons with landslides triggered by other earthquakes to show that most or all of the old coherent slides and earth flows formed during the 1811-12 New Madrid earthquakes. Evidence clearly indicates that the only large, aseismic landslide activity in the area results from fluvial undercutting of near-river bluffs. This erosion of the base of the bluffs triggers slumps that are morphologically distinct from the old slumps on bluffs away from the river. Our conclusions are consistent with the findings of other recent investigations of the same landslides that indicate extensive seismic triggering of coherent slides and earth flows during the 1811-12 New Madrid earthquakes.

  8. Landslide Distribution, Damage and Land Use Interactions During the 2004 Chuetsu Earthquake

    NASA Astrophysics Data System (ADS)

    Sidle, R. C.; Trandafir, A. C.; Kamai, T.

    2005-05-01

    A series of earthquakes struck Niigata Prefecture, Japan, on 23 October 2004 killing about 40 people and injuring about 3000. These earthquakes were characterized by a shallow focal depth (13 km) that generated strong levels of ground motion, resulting in extensive damage and thousands of landslides throughout the region. Most landslides on natural slopes occurred in the regional geological structure consisting of sandy siltstone and thin-bedded alternations of sandstone and siltstone. Earthquakes exacerbate such potential instabilities by the ground motion induced and the enhancement of pore water pressure in wet regoliths. The three strongest earthquakes occurred within a period of less than 40 minutes, and had sequential magnitudes (JMA) of 6.8, 6.3, and 6.5. The highest density of landslides (12/km2) was mapped within a 2.9 km radius of the M6.5 epicenter near Yamakoshi village; about 4 times higher density compared to the other epicenters located to the east and west. This higher density may be a consequence of the cumulative shaking effects associated with the two earlier earthquakes of M6.8 and 6.5, in addition to the topographic and geologic factors controlling the stability of the region. Roads, residential fills, agricultural terraces on hillslopes, and other earthworks increased the susceptibility of sites to slope failure. Numerous earthquake-induced failures in terraces and adjacent hillslopes around rice paddy fields occurred near Yamakoshi village. A housing development in Nagaoka city constructed on an old earthflow suffered from severe damage to fill slopes during the earthquake. Nearly saturated conditions in these deep fills together with poor drainage systems contributed to the landslide damages. Clearly, land use activities in rural and urban areas exacerbated the extent of earthquake-triggered landslides.

  9. A preliminary regional assessment of earthquake-induced landslide susceptibility for Vrancea Seismic Region

    NASA Astrophysics Data System (ADS)

    Micu, Mihai; Balteanu, Dan; Ionescu, Constantin; Havenith, Hans; Radulian, Mircea; van Westen, Cees; Damen, Michiel; Jurchescu, Marta

    2015-04-01

    In seismically-active regions, earthquakes may trigger landslides enhancing the short-to-long term slope denudation and sediment delivery and conditioning the general landscape evolution. Co-seismic slope failures present in general a low frequency - high magnitude pattern which should be addressed accordingly by landslide hazard assessment, with respect to the generally more frequent precipitation-triggered landslides. The Vrancea Seismic Region, corresponding to the curvature sector of the Eastern Romanian Carpathians, represents the most active sub-crustal (focal depth > 50 km) earthquake province of Europe. It represents the main seismic energy source throughout Romania with significant transboundary effects recorded as far as Ukraine and Bulgaria. During the last 300 years, the region featured 14 earthquakes with M>7, among which seven events with magnitude above 7.5 and three between 7.7 and 7.9. Apart from the direct damages, the Vrancea earthquakes are also responsible for causing numerous other geohazards, such as ground fracturing, groundwater level disturbances and possible deep-seated landslide occurrences (rock slumps, rock-block slides, rock falls, rock avalanches). The older deep-seated landslides (assumed to have been) triggered by earthquakes usually affect the entire slope profile. They often formed landslide dams strongly influencing the river morphology and representing potential threats (through flash-floods) in case of lake outburst. Despite the large potential of this research issue, the correlation between the region's seismotectonic context and landslide predisposing factors has not yet been entirely understood. Presently, there is a lack of information provided by the geohazards databases of Vrancea that does not allow us to outline the seismic influence on the triggering of slope failures in this region. We only know that the morphology of numerous large, deep-seated and dormant landslides (which can possibly be reactivated in future

  10. Assessment of tsunami hazard to the U.S. East Coast using relationships between submarine landslides and earthquakes

    ten Brink, Uri S.; Lee, H.J.; Geist, E.L.; Twichell, D.

    2009-01-01

    Submarine landslides along the continental slope of the U.S. Atlantic margin are potential sources for tsunamis along the U.S. East coast. The magnitude of potential tsunamis depends on the volume and location of the landslides, and tsunami frequency depends on their recurrence interval. However, the size and recurrence interval of submarine landslides along the U.S. Atlantic margin is poorly known. Well-studied landslide-generated tsunamis in other parts of the world have been shown to be associated with earthquakes. Because the size distribution and recurrence interval of earthquakes is generally better known than those for submarine landslides, we propose here to estimate the size and recurrence interval of submarine landslides from the size and recurrence interval of earthquakes in the near vicinity of the said landslides. To do so, we calculate maximum expected landslide size for a given earthquake magnitude, use recurrence interval of earthquakes to estimate recurrence interval of landslide, and assume a threshold landslide size that can generate a destructive tsunami. The maximum expected landslide size for a given earthquake magnitude is calculated in 3 ways: by slope stability analysis for catastrophic slope failure on the Atlantic continental margin, by using land-based compilation of maximum observed distance from earthquake to liquefaction, and by using land-based compilation of maximum observed area of earthquake-induced landslides. We find that the calculated distances and failure areas from the slope stability analysis is similar or slightly smaller than the maximum triggering distances and failure areas in subaerial observations. The results from all three methods compare well with the slope failure observations of the Mw = 7.2, 1929 Grand Banks earthquake, the only historical tsunamigenic earthquake along the North American Atlantic margin. The results further suggest that a Mw = 7.5 earthquake (the largest expected earthquake in the eastern U

  11. Impact of landsliding on chemical weathering in the volcanic island of Reunion

    NASA Astrophysics Data System (ADS)

    Gayer, E.; Lucas, A.; Bouchez, J.; Sy, A.; Louvat, P.; Gaillardet, J.; Dosseto, A.; Kuessner, M.; Michon, L.; Yokochi, R.

    2017-12-01

    Tropical precipitation regimes allow for strong erosion that creates dramatic landscapes. Understanding and quantifying erosion processes in tropical volcanic islands is important for both scientific challenges (e.g. regarding their implications for global biogeochemical cycles and their links with climate) and societal matters (e.g. socio-economic and ecosystem damages in highly populated areas). Despite the fact that the link between chemical weathering and physical erosion has long been studied, most research has focused on active mountain ranges. Here we use Reunion Island as a natural laboratory to explore this link in a tectonically inactive environment.In Reunion, estimates show that intense erosion rates are mainly due to stochastic bedrock landsliding. Although landslides affect only a small portion of the landscape they supply rivers with huge amounts of fresh broken rocks and organic matter, which are then available for chemical alteration and for transport. In this study, we measured water chemistry of several streams in Reunion and of landslide seepage water sampled on 2 majors landslides ("Grand Éboulis" and "Mahavel", both > 50 yrs old). Seepage samples from Grand Éboulis show high Total Dissolved Solids (TDS) compared to local streams, in agreement with previous observations showing that landslides promote chemical weathering [1]. However, the low TDS of the Mahavel seep water samples compared to local streams, suggest that the impact of landslides on weathering fluxes may strongly depend on the rate at which landslide debris are transferred downstream and their subsequent residence time in the catchment. In order to calculate such sediment transfer rates in Mahavel, we developed an automated photogrammetric workflow allowing for deriving Digital Elevation Models from historical aerial photos. Using the 30 years of images archived at the Institut Geographique National (5 campaigns), we will be able to delineate the extent of landslide debris, to

  12. Identifying a large landslide with small displacements in a zone of coseismic tectonic deformation; the Villa Del Monte landslide triggered by the 1989 Loma Prieta, California, earthquake

    Keefer, David K.; Harp, Edwin L.; Griggs, Gary B.; Evans, Stephen G.; DeGraff, Jerome V.

    2002-01-01

    The Villa Del Monte landslide was one of 20 large and complex landslides triggered by the 1989 LomaPrieta, California, earthquake in a zone of pervasive coseismicground cracking near the fault rupture. The landslide was approximately 980 m long, 870 m wide, and encompassed an area of approximately 68 ha. Drilling data suggested that movement may have extended to depths as great as 85 m below the ground surface. Even though the landslide moved <1 m, it caused substantial damage to numerous dwellings and other structures, primarily as a result of differential displacements and internal Assuring. Surface cracks, scarps, and compression features delineating the Villa Del Monte landslide were discontinuous, probably because coseismic displacements were small; such discontinuous features were also characteristic of the other large, coseismic landslides in the area, which also moved only short distances during the earthquake. Because features marking landslide boundaries were discontinuous and because other types of coseismic ground cracks were widespread in the area, identification of the landslides required detailed mapping and analysis. Recognition that landslides such as that at Villa Del Monte may occur near earthquake-generating fault ruptures should aid in future hazard evaluations of areas along active faults.

  13. New insights from IODP Expedition 340 offshore Montserrat: First drilling of large volcanic island landslides

    NASA Astrophysics Data System (ADS)

    Talling, Peter; Le Friant, Anne; Ishizuka, Osamu; Watt, Sebastian; Coussens, Maya; Jutzeler, Martin; Wall-Palmer, Deborah; Palmer, Martin; Cassidy, Michael; Kataoka, Kyoko; Endo, Daisuko; McCanta, Molly; Trofimovs, Jessica; Hatfield, Robert; Stinton, Adam; Lebas, Elodie; Boudon, Georges; Expedition 340 Shipboard Science Party, IODP

    2015-04-01

    Montserrat now provides one of the most complete datasets for understanding the character and tempo of hazardous events at volcanic islands. Much of the erupted material ends up offshore, and this offshore record may be easier to date due to intervening hemiplegic sediments between event beds. The offshore dataset includes the first scientific drilling of volcanic island landslides during IODP Expedition 340, together with an unusually comprehensive set of shallow sediment cores and 2-D and 3-D seismic surveys. Most recently in 2013, Remotely Operated Vehicle (ROV) dives mapped and sampled the surface of the main landslide deposits. This contribution aims to provide an overview of key insights from ongoing work on IODP Expedition 340 Sites offshore Montserrat.Key objectives are to understand the composition (and hence source), emplacement mechanism (and hence tsunami generation) of major landslides, together with their frequency and timing relative to volcanic eruption cycles. The most recent major collapse event is Deposit 1, which involved ~1.8 km cubed of material and produced a blocky deposit at ~12-14ka. Deposit 1 appears to have involved not only the volcanic edifice, but also a substantial component of a fringing bioclastic shelf, and material locally incorporated from the underlying seafloor. This information allows us to test how first-order landslide morphology (e.g. blocky or elongate lobes) is related to first-order landslide composition. Preliminary analysis suggests that Deposit 1 occurred shortly before a second major landslide on the SW of the island (Deposit 5). It may have initiated English's Crater, but was not associated with a major change in magma composition. An associated turbidite-stack suggests it was emplaced in multiple stages, separated by at least a few hours and thus reducing the tsunami magnitude. The ROV dives show that mega-blocks in detail comprise smaller-scale breccias, which can travel significant distances without complete

  14. Evolution of earthquake-triggered landslides in the Kashmir Himalaya, northern Pakistan

    Khattak, G.A.; Owen, L.A.; Kamp, U.; Harp, E.L.

    2010-01-01

    The influence of the 08 October 2005 Kashmir earthquake and subsequent snow melt and monsoon rainfall on slope stability was evaluated using repeat photography in the Kashmir Himalaya of northern Pakistan. Sixty-eight landslide-affected locations were selected and photographed in November 2005, May/June 2006, June 2007, and August 2007 to evaluate all potential geomorphic changes. Eighty percent of the locations showed no or very little change, 11% of the locations showed a partial vegetation recovery on the slopes, while 9% showed an increase in the landslide area. All those locations that showed an increase in landsliding were located along rivers and/or roads. The small change in landslide extent is remarkable given that the region experienced one of the heaviest monsoon seasons in the last decade and is counter to earlier predictions of accelerated slope erosion by landsliding in the immediate years following the earthquake. Extensive fissures and ground cracks at many localities, however, still present a potential of future landsliding under wetter conditions. ?? 2009 Elsevier B.V. All rights reserved.

  15. Segmentation and Classification of Nepal Earthquake Induced Landslides Using SENTINEL-1 Product

    NASA Astrophysics Data System (ADS)

    Kunwar, Saket

    2016-06-01

    On April 26, 2015, an earthquake of magnitude 7.8 on the Richter scale occurred, with epicentre at Barpak (28°12'20''N,84°44'19''E), Nepal. Landslides induced due to the earthquake and its aftershock added to the natural disaster claiming more than 9000 lives. Landslides represented as lines that extend from the head scarp to the toe of the deposit were mapped by the staff of the British Geological Survey and is available freely under Open Data Commons Open Database License(ODC-ODbL) license at the Humanitarian Data Exchange Program. This collection of 5578 landslides is used as preliminary ground truth in this study with the aim of producing polygonal delineation of the landslides from the polylines via object oriented segmentation. Texture measures from Sentinel-1a Ground Range Detected (GRD) Amplitude data and eigenvalue-decomposed Single Look Complex (SLC) polarimetry product are stacked for this purpose. This has also enabled the investigation of landslide properties in the H-Alpha plane, while developing a classification mechanism for identifying the occurrence of landslides.

  16. Characteristics of Landslides Triggered by Mw 7.8 2015 Gorkha Earthquake

    NASA Astrophysics Data System (ADS)

    Dhital, Smriti

    The Mw 7.8 Gorkha earthquake struck central Nepal on April 25, 2015 and brought about a huge loss of life and property. The quake was also responsible for the generation of a large number of landslides. They blocked highways, devastated villages, and temporarily dammed some rivers. About 14,670 landslips were triggered off by the main shock and its numerous large aftershocks. Among the detected failures, about 23% had an area greater than 100 m2. Since such failures can directly affect people's life and property, they are considered for further investigation in this study. A comparison of these coseismic landslides with the 29 historical failures reveals that these landslides slightly exceed in number from those expected for the peak ground acceleration observed due to these earthquakes. The landslides seem to be concentrated within the area of the fault rupture surface. About 90% of the detected landslips could be classified as earth falls. The areas having relatively soft rocks, such as slates, shales, schists and phyllites of the Lesser Himalaya, suffered from a greater number of failures. The landslides had a strong correlation with the peak ground acceleration and they also showed a positive correlation with some landslide-susceptible geological formations composing the study area.

  17. Evidences of landslide earthquake triggering due to self-excitation process

    NASA Astrophysics Data System (ADS)

    Bozzano, F.; Lenti, L.; Martino, Salvatore; Paciello, A.; Scarascia Mugnozza, G.

    2011-06-01

    The basin-like setting of stiff bedrock combined with pre-existing landslide masses can contribute to seismic amplifications in a wide frequency range (0-10 Hz) and induce a self-excitation process responsible for earthquake-triggered landsliding. Here, the self-excitation process is proposed to justify the far-field seismic trigger of the Cerda landslide (Sicily, Italy) which was reactivated by the 6th September 2002 Palermo earthquake ( M s = 5.4), about 50 km far from the epicentre. The landslide caused damage to farm houses, roads and aqueducts, close to the village of Cerda, and involved about 40 × 106 m3 of clay shales; the first ground cracks due to the landslide movement formed about 30 min after the main shock. A stress-strain dynamic numerical modelling, performed by FDM code FLAC 5.0, supports the notion that the combination of local geological setting and earthquake frequency content played a fundamental role in the landslide reactivation. Since accelerometric records of the triggering event are not available, dynamic equivalent inputs have been used for the numerical modelling. These inputs can be regarded as representative for the local ground shaking, having a PGA value up to 0.2 m/s2, which is the maximum expected in 475 years, according to the Italian seismic hazard maps. A 2D numerical modelling of the seismic wave propagation in the Cerda landslide area was also performed; it pointed out amplification effects due to both the structural setting of the stiff bedrock (at about 1 Hz) and the pre-existing landslide mass (in the range 3-6 Hz). The frequency peaks of the resulting amplification functions ( A( f)) fit well the H/ V spectral ratios from ambient noise and the H/ H spectral ratios to a reference station from earthquake records, obtained by in situ velocimetric measurements. Moreover, the Fourier spectra of earthquake accelerometric records, whose source and magnitude are consistent with the triggering event, show a main peak at about 1 Hz

  18. Rapid field-based landslide hazard assessment in response to post-earthquake emergency

    NASA Astrophysics Data System (ADS)

    Frattini, Paolo; Gambini, Stefano; Cancelliere, Giorgio

    2016-04-01

    On April 25, 2015 a Mw 7.8 earthquake occurred 80 km to the northwest of Kathmandu (Nepal). The largest aftershock, occurred on May 12, 2015, was the Mw 7.3 Nepal earthquake (SE of Zham, China), 80 km to the east of Kathmandu. . The earthquakes killed ~9000 people and severely damaged a 10,000 sqkm region in Nepal and neighboring countries. Several thousands of landslides have been triggered during the event, causing widespread damages to mountain villages and the evacuation of thousands of people. Rasuwa was one of the most damaged districts. This contribution describes landslide hazard analysis of the Saramthali, Yarsa and Bhorle VDCs (122 km2, Rasuwa district). Hazard is expressed in terms of qualitative classes (low, medium, high), through a simple matrix approach that combines frequency classes and magnitude classes. The hazard analysis is based primarily on the experience gained during a field survey conducted in September 2014. During the survey, local knowledge has been systematically exploited through interviews with local people that have experienced the earthquake and the coseismic landslides. People helped us to recognize fractures and active deformations, and allowed to reconstruct a correct chronicle of landslide events, in order to assign the landslide events to the first shock, the second shock, or the post-earthquake 2015 monsoon. The field experience was complemented with a standard analysis of the relationship between potential controlling factors and the distribution of landslides reported in Kargel et al (2016). This analysis allowed recognizing the most important controlling factor. This information was integrated with the field observations to verify the mapped units and to complete the mapping in area not accessible for field activity. Finally, the work was completed with the analysis and the use of a detailed landslide inventory produced by the University of Milano Bicocca that covers most of the area affected by coseismic landslides in

  19. Presentation and analysis of a worldwide database of earthquake-induced landslide inventories

    Tanyas, Hakan; van Westen, Cees J.; Allstadt, Kate E.; Nowicki Jessee, M. Anna; Gorum, Tolga; Jibson, Randall W.; Godt, Jonathan W.; Sato, Hiroshi P.; Schmitt, Robert G.; Marc, Odin; Hovius, Niels

    2017-01-01

    Earthquake-induced landslide (EQIL) inventories are essential tools to extend our knowledge of the relationship between earthquakes and the landslides they can trigger. Regrettably, such inventories are difficult to generate and therefore scarce, and the available ones differ in terms of their quality and level of completeness. Moreover, access to existing EQIL inventories is currently difficult because there is no centralized database. To address these issues, we compiled EQIL inventories from around the globe based on an extensive literature study. The database contains information on 363 landslide-triggering earthquakes and includes 66 digital landslide inventories. To make these data openly available, we created a repository to host the digital inventories that we have permission to redistribute through the U.S. Geological Survey ScienceBase platform. It can grow over time as more authors contribute their inventories. We analyze the distribution of EQIL events by time period and location, more specifically breaking down the distribution by continent, country, and mountain region. Additionally, we analyze frequency distributions of EQIL characteristics, such as the approximate area affected by landslides, total number of landslides, maximum distance from fault rupture zone, and distance from epicenter when the fault plane location is unknown. For the available digital EQIL inventories, we examine the underlying characteristics of landslide size, topographic slope, roughness, local relief, distance to streams, peak ground acceleration, peak ground velocity, and Modified Mercalli Intensity. Also, we present an evaluation system to help users assess the suitability of the available inventories for different types of EQIL studies and model development.

  20. Presentation and Analysis of a Worldwide Database of Earthquake-Induced Landslide Inventories

    NASA Astrophysics Data System (ADS)

    Tanyaş, Hakan; van Westen, Cees J.; Allstadt, Kate E.; Anna Nowicki Jessee, M.; Görüm, Tolga; Jibson, Randall W.; Godt, Jonathan W.; Sato, Hiroshi P.; Schmitt, Robert G.; Marc, Odin; Hovius, Niels

    2017-10-01

    Earthquake-induced landslide (EQIL) inventories are essential tools to extend our knowledge of the relationship between earthquakes and the landslides they can trigger. Regrettably, such inventories are difficult to generate and therefore scarce, and the available ones differ in terms of their quality and level of completeness. Moreover, access to existing EQIL inventories is currently difficult because there is no centralized database. To address these issues, we compiled EQIL inventories from around the globe based on an extensive literature study. The database contains information on 363 landslide-triggering earthquakes and includes 66 digital landslide inventories. To make these data openly available, we created a repository to host the digital inventories that we have permission to redistribute through the U.S. Geological Survey ScienceBase platform. It can grow over time as more authors contribute their inventories. We analyze the distribution of EQIL events by time period and location, more specifically breaking down the distribution by continent, country, and mountain region. Additionally, we analyze frequency distributions of EQIL characteristics, such as the approximate area affected by landslides, total number of landslides, maximum distance from fault rupture zone, and distance from epicenter when the fault plane location is unknown. For the available digital EQIL inventories, we examine the underlying characteristics of landslide size, topographic slope, roughness, local relief, distance to streams, peak ground acceleration, peak ground velocity, and Modified Mercalli Intensity. Also, we present an evaluation system to help users assess the suitability of the available inventories for different types of EQIL studies and model development.

  1. Detecting and Characterizing Repeating Earthquake Sequences During Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Tepp, G.; Haney, M. M.; Wech, A.

    2017-12-01

    A major challenge in volcano seismology is forecasting eruptions. Repeating earthquake sequences often precede volcanic eruptions or lava dome activity, providing an opportunity for short-term eruption forecasting. Automatic detection of these sequences can lead to timely eruption notification and aid in continuous monitoring of volcanic systems. However, repeating earthquake sequences may also occur after eruptions or along with magma intrusions that do not immediately lead to an eruption. This additional challenge requires a better understanding of the processes involved in producing these sequences to distinguish those that are precursory. Calculation of the inverse moment rate and concepts from the material failure forecast method can lead to such insights. The temporal evolution of the inverse moment rate is observed to differ for precursory and non-precursory sequences, and multiple earthquake sequences may occur concurrently. These observations suggest that sequences may occur in different locations or through different processes. We developed an automated repeating earthquake sequence detector and near real-time alarm to send alerts when an in-progress sequence is identified. Near real-time inverse moment rate measurements can further improve our ability to forecast eruptions by allowing for characterization of sequences. We apply the detector to eruptions of two Alaskan volcanoes: Bogoslof in 2016-2017 and Redoubt Volcano in 2009. The Bogoslof eruption produced almost 40 repeating earthquake sequences between its start in mid-December 2016 and early June 2017, 21 of which preceded an explosive eruption, and 2 sequences in the months before eruptive activity. Three of the sequences occurred after the implementation of the alarm in late March 2017 and successfully triggered alerts. The nearest seismometers to Bogoslof are over 45 km away, requiring a detector that can work with few stations and a relatively low signal-to-noise ratio. During the Redoubt

  2. Rapid Extraction of Landslide and Spatial Distribution Analysis after Jiuzhaigou Ms7.0 Earthquake Based on Uav Images

    NASA Astrophysics Data System (ADS)

    Jiao, Q. S.; Luo, Y.; Shen, W. H.; Li, Q.; Wang, X.

    2018-04-01

    Jiuzhaigou earthquake led to the collapse of the mountains and formed lots of landslides in Jiuzhaigou scenic spot and surrounding roads which caused road blockage and serious ecological damage. Due to the urgency of the rescue, the authors carried unmanned aerial vehicle (UAV) and entered the disaster area as early as August 9 to obtain the aerial images near the epicenter. On the basis of summarizing the earthquake landslides characteristics in aerial images, by using the object-oriented analysis method, landslides image objects were obtained by multi-scale segmentation, and the feature rule set of each level was automatically built by SEaTH (Separability and Thresholds) algorithm to realize the rapid landslide extraction. Compared with visual interpretation, object-oriented automatic landslides extraction method achieved an accuracy of 94.3 %. The spatial distribution of the earthquake landslide had a significant positive correlation with slope and relief and had a negative correlation with the roughness, but no obvious correlation with the aspect. The relationship between the landslide and the aspect was not found and the probable reason may be that the distance between the study area and the seismogenic fault was too far away. This work provided technical support for the earthquake field emergency, earthquake landslide prediction and disaster loss assessment.

  3. Identifying slow-moving landslides using LiDAR DEM and SAR interferometry: An Example of 2006 Meinong Earthquake

    NASA Astrophysics Data System (ADS)

    Chen, R. F.; Lin, C. W.; Hsu, Y. J.; Zhang, L.; Liang, H. Y.

    2017-12-01

    The February 6 Meinong Earthquake of 2016 (ML=6.4; at 23.85ºN, 120.81ºE), with a focal depth of 16.7 km, was triggered by an unknown blind thrust in southern Taiwan. The earthquake not only induced coseismic crustal deformation, but also triggered slow-moving landslides nearby the Longchuan active fault. In this study, high-resolution LiDAR derived DEM of 2010 is used to recognize locations of previous slow-moving landslides according to their topographic signatures, such as main escarpment, trench, double ridge, and crown cracks. Within an area of 4.5 km x 1.8 km along Longchuan fault near the ridge of Longchuan mountain, over 50 sites with landslide signatures are recognized, and three of them are over 10 ha. These earthquake-induced landslide deformations are detected from InSAR (synthetic aperture radar interferometry) images using Advanced Land Observing Satellite ALOS2/Phased-array L band and Sentinel 1 C-band SAR (PALSAR) data taken before and after the earthquake; some significant landslide deformation are even overlapped with areas where previous slow moving landslides were identified on the LiDAR DEM. Additionally, field investigation right after the earthquake in the study area also support that these previously identified landslides reactivated in the earthquake. Although these landslides do not cause serious damage due to their minor displacement in the Meinong Earthquake, the study results prove that LiDAR DEM is a powerful tool to identify and continuously monitor slow-motion landslides for preventing catastrophic failures that may be caused by hazardous earthquake or heavy rainfall.

  4. Evaluation of CAMEL - comprehensive areal model of earthquake-induced landslides

    Miles, S.B.; Keefer, D.K.

    2009-01-01

    A new comprehensive areal model of earthquake-induced landslides (CAMEL) has been developed to assist in planning decisions related to disaster risk reduction. CAMEL provides an integrated framework for modeling all types of earthquake-induced landslides using fuzzy logic systems and geographic information systems. CAMEL is designed to facilitate quantitative and qualitative representation of terrain conditions and knowledge about these conditions on the likely areal concentration of each landslide type. CAMEL has been empirically evaluated with respect to disrupted landslides (Category I) using a case study of the 1989 M = 6.9 Loma Prieta, CA earthquake. In this case, CAMEL performs best in comparison to disrupted slides and falls in soil. For disrupted rock fall and slides, CAMEL's performance was slightly poorer. The model predicted a low occurrence of rock avalanches, when none in fact occurred. A similar comparison with the Loma Prieta case study was also conducted using a simplified Newmark displacement model. The area under the curve method of evaluation was used in order to draw comparisons between both models, revealing improved performance with CAMEL. CAMEL should not however be viewed as a strict alternative to Newmark displacement models. CAMEL can be used to integrate Newmark displacements with other, previously incompatible, types of knowledge. ?? 2008 Elsevier B.V.

  5. GIS-based support vector machine modeling of earthquake-triggered landslide susceptibility in the Jianjiang River watershed, China

    NASA Astrophysics Data System (ADS)

    Xu, Chong; Dai, Fuchu; Xu, Xiwei; Lee, Yuan Hsi

    2012-04-01

    Support vector machine (SVM) modeling is based on statistical learning theory. It involves a training phase with associated input and target output values. In recent years, the method has become increasingly popular. The main purpose of this study is to evaluate the mapping power of SVM modeling in earthquake triggered landslide-susceptibility mapping for a section of the Jianjiang River watershed using a Geographic Information System (GIS) software. The river was affected by the Wenchuan earthquake of May 12, 2008. Visual interpretation of colored aerial photographs of 1-m resolution and extensive field surveys provided a detailed landslide inventory map containing 3147 landslides related to the 2008 Wenchuan earthquake. Elevation, slope angle, slope aspect, distance from seismogenic faults, distance from drainages, and lithology were used as the controlling parameters. For modeling, three groups of positive and negative training samples were used in concert with four different kernel functions. Positive training samples include the centroids of 500 large landslides, those of all 3147 landslides, and 5000 randomly selected points in landslide polygons. Negative training samples include 500, 3147, and 5000 randomly selected points on slopes that remained stable during the Wenchuan earthquake. The four kernel functions are linear, polynomial, radial basis, and sigmoid. In total, 12 cases of landslide susceptibility were mapped. Comparative analyses of landslide-susceptibility probability and area relation curves show that both the polynomial and radial basis functions suitably classified the input data as either landslide positive or negative though the radial basis function was more successful. The 12 generated landslide-susceptibility maps were compared with known landslide centroid locations and landslide polygons to verify the success rate and predictive accuracy of each model. The 12 results were further validated using area-under-curve analysis. Group 3 with

  6. The effect of complex fault rupture on the distribution of landslides triggered by the 12 January 2010, Haiti earthquake

    Harp, Edwin L.; Jibson, Randall W.; Dart, Richard L.; Margottini, Claudio; Canuti, Paolo; Sassa, Kyoji

    2013-01-01

    The MW 7.0, 12 January 2010, Haiti earthquake triggered more than 7,000 landslides in the mountainous terrain south of Port-au-Prince over an area that extends approximately 50 km to the east and west from the epicenter and to the southern coast. Most of the triggered landslides were rock and soil slides from 25°–65° slopes within heavily fractured limestone and deeply weathered basalt and basaltic breccia. Landslide volumes ranged from tens of cubic meters to several thousand cubic meters. Rock slides in limestone typically were 2–5 m thick; slides within soils and weathered basalt typically were less than 1 m thick. Twenty to thirty larger landslides having volumes greater than 10,000 m3 were triggered by the earthquake; these included block slides and rotational slumps in limestone bedrock. Only a few landslides larger than 5,000 m3 occurred in the weathered basalt. The distribution of landslides is asymmetric with respect to the fault source and epicenter. Relatively few landslides were triggered north of the fault source on the hanging wall. The densest landslide concentrations lie south of the fault source and the Enriquillo-Plantain-Garden fault zone on the footwall. Numerous landslides also occurred along the south coast west of Jacmél. This asymmetric distribution of landsliding with respect to the fault source is unusual given the modeled displacement of the fault source as mainly thrust motion to the south on a plane dipping to the north at approximately 55°; landslide concentrations in other documented thrust earthquakes generally have been greatest on the hanging wall. This apparent inconsistency of the landslide distribution with respect to the fault model remains poorly understood given the lack of any strong-motion instruments within Haiti during the earthquake.

  7. Export Time of Earthquake-Derived Landslides in Active Mountain Ranges

    NASA Astrophysics Data System (ADS)

    Croissant, T.; Lague, D.; Steer, P.; Davy, P.

    2016-12-01

    In active mountain ranges, large earthquakes (Mw > 5-6) trigger numerous landslides that impact river dynamics. These landslides bring local and sudden sediment deposits which are eroded and transported along the river network, causing downstream changes in river geometry, transport capacity and erosion efficiency. The progressive removal of landslide materials has implications for downstream hazards management and for landscape dynamics at the timescale of the seismic cycle. Although the export time of suspended sediments from landslides triggered by large-magnitude earthquakes has been extensively studied, the processes and time scales associated to bedload transport remains poorly studied. Here, we study the sediment export of large landslides with the 2D morphodynamic model, Eros. This model combines: (i) an hydrodynamic model, (ii) a sediment transport and deposition model and (iii) a lateral erosion model. Eros is particularly well suited for this issue as it accounts for the complex retro-actions between sediment transport and fluvial geometry for rivers submitted to external forcings such as abrupt sediment supply increase. Using a simplified synthetic topography we systematically study the influence of pulse volume (Vs) and channel transport capacity (QT) on the export time of landslides. The range of simulated river behavior includes landslide vertical incision, its subsequent removal by lateral erosion and the river morphology modifications induced by downstream sediment propagation. The morphodynamic adaptation of the river increases its transport capacity along the channel and tends to accelerate the landslide evacuation. Our results highlight two regimes: (i) the export time is linearly related to Vs/QT when the sediment pulse introduced in the river does not affect significantly the river hydrodynamic (low Vs/QT) and (ii) the export time is a non-linear function of Vs/QT when the pulse undergoes significant morphodynamic modifications during its

  8. Comparison of Structurally Controlled Landslide Hazard Simulation to the Co-seismic Landslides Caused by the M 7.2 2013 Bohol Earthquake.

    NASA Astrophysics Data System (ADS)

    Galang, J. A. M. B.; Eco, R. C.; Lagmay, A. M. A.

    2014-12-01

    The M_w 7.2 October 15, 2013 Bohol earthquake is one of the more destructive earthquake to hit the Philippines in the 21st century. The epicenter was located in Sagbayan municipality, central Bohol and was generated by a previously unmapped reverse fault called the "Inabanga Fault". The earthquake resulted in 209 fatalities and over 57 million USD worth of damages. The earthquake generated co-seismic landslides most of which were related to fault structures. Unlike rainfall induced landslides, the trigger for co-seismic landslides happen without warning. Preparations for this type of landslides rely heavily on the identification of fracture-related slope instability. To mitigate the impacts of co-seismic landslide hazards, morpho-structural orientations of discontinuity sets were mapped using remote sensing techniques with the aid of a Digital Terrain Model (DTM) obtained in 2012. The DTM used is an IFSAR derived image with a 5-meter pixel resolution and approximately 0.5 meter vertical accuracy. Coltop 3D software was then used to identify similar structures including measurement of their dip and dip directions. The chosen discontinuity sets were then keyed into Matterocking software to identify potential rock slide zones due to planar or wedged discontinuities. After identifying the structurally-controlled unstable slopes, the rock mass propagation extent of the possible rock slides was simulated using Conefall. Separately, a manually derived landslide inventory has been performed using post-earthquake satellite images and LIDAR. The results were compared to the landslide inventory which identified at least 873 landslides. Out of the 873 landslides identified through the inventory, 786 or 90% intersect the simulated structural-controlled landslide hazard areas of Bohol. The results show the potential of this method to identify co-seismic landslide hazard areas for disaster mitigation. Along with computer methods to simulate shallow landslides, and debris flow

  9. Gradual decay of elevated landslide rates after a large earthquake in the Finisterre Mountains, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Hovius, N.; Marc, O.

    2013-12-01

    Large earthquakes can cause widespread mass wasting and landslide rates can stay high after a seismic event. The rate of decay of seismically enhanced mass wasting determines the total erosional effect of an earthquake. It is also an important term in the post-seismic redevelopment of epicentral areas. Using a time series of Landsat images spanning 1990-2010, we have determined the evolution of landslide rates in the western Finisterre Mountains, Papua New Guinea. There, two earthquakes with Mw 6.7and 6.9 occurred at depth of about 20 km on the range-bounding Ramu-Markam fault in 1993. These earthquakes triggered landslides with a total volume of about 0.15 km3. Landslide rates were up to four orders of magnitude higher after the earthquakes than in preceding years, decaying to background values over a period of 2-3 years. Due to this short decay time, seismically induced landslides added only 5% to the volume of co-seismic landslides. This contrasts with another well-documented example, the 1999 Chi-Chi earthquake in Taiwan, where post-seismic landsliding may have increased the total eroded volume by a factor 3-5. In the Finisterre case, landslide rates may have been slightly less than normal for up to a decade after the decay period, but this effect is partially obscured by the impact of a smaller earthquake in 1997. Regardless, the rate of decay of landslide incidence was unrelated to both the seismic moment release in aftershocks and local precipitation. A control on this decay rate has not yet been identified.

  10. Typhoon-driven landsliding induces earthquakes: example of the 2009 Morakot typhoon

    NASA Astrophysics Data System (ADS)

    Steer, Philippe; Jeandet, Louise; Cubas, Nadaya; Marc, Odin; Meunier, Patrick; Hovius, Niels; Simoes, Martine; Cattin, Rodolphe; Shyu, J. Bruce H.; Liang, Wen-Tzong; Theunissen, Thomas; Chiang, Shou-Hao

    2017-04-01

    Extreme rainfall events can trigger numerous landslides in mountainous areas and a prolonged increase of river sediment load. The resulting mass transfer at the Earth surface in turn induces stress changes at depth, which could be sufficient to trigger shallow earthquakes. The 2009 Morakot typhoon represents a good case study as it delivered 3 m of precipitation in 3 days and caused some of the most intense erosion ever recorded. Analysis of seismicity time-series before and after the Morakot typhoon reveals a systematic increase of shallow (i.e. 0-15 km of depth) earthquake frequency in the vicinity of the areas displaying a high spatial density of landslides. This step-like increase in frequency lasts for at least 2-3 years and does not follow an Omori-type aftershock sequence. Rather, it is associated to a step change of the Gutenberg-Richter b-value of the earthquake catalog. Both changes occurred in mountainous areas of southwest Taiwan, where typhoon Morakot caused extensive landsliding. These spatial and temporal correlations strongly suggest a causal relationship between the Morakot-triggered landslides and the increase of earthquake frequency and their associated b-value. We propose that the progressive removal of landslide materials from the steep mountain landscape by river sediment transport acts as an approximately constant increase of the stress rate with respect to pre-typhoon conditions, and that this in turn causes a step-wise increase in earthquake frequency. To test this hypothesis, we investigate the response of a rate-and-state fault to stress changes using a 2-D continuum elasto-dynamic model. Consistent with the results of Ader et al. (2013), our preliminary results show a step-like increase of earthquake frequency in response to a step-like decrease of the fault normal stress. We also investigate the sensitivity of the amplitude and time-scale of the earthquake frequency increase to the amplitude of the normal stress change and to

  11. Impact of Landslides Induced by Earthquake on Hydrologic Response in a Mountainous Catchment

    NASA Astrophysics Data System (ADS)

    Qian, Q.; Su, D.; Ran, Q.

    2013-12-01

    The changes of the underlying surface conditions (topography, vegetation cover rate, etc.), which were caused by the numerous landslides in the Wenchuan earthquake, may influence the hydrologic response and then change the flash flood or other kinds of the disaster risk in the affected areas. The Jianpinggou catchment, located in Sichuan China, is selected as the study area for this paper. It is a steep-slope mountainous catchment, flash flood is the main disaster, and sometimes causes the debris flow. The distribution of the landslides in this catchment is obtained from the remote sensing image data. The changes of topography are obtained from the comparisons among the different periods of digital elevation models (DEMs). A physical-based model, the Integrated Hydrology Model (InHM), is used to simulate the hydrologic response before and after the landslide, respectively. The influence of the underlying surface conditions is then discussed based on the output data, such as the hydrograph, distributed water depth and local runoff. The study leads to the following generalized conclusions: 1) the impact of the landslides on hydrologic response does exist, and the greater the proportion of surface flow in the total runoff is, the greater the impact will be; 2) the peak flow from the outlet increased after the landslide, but the shape of the hydrograph has little change; 3) the effect of the landslides on the local runoff is relatively obvious, and this elevates the local flash floods risk; 4) the difference of hydrologic responses between the two periods (before and after the landslide occurring) becomes larger with the increasing rainfall, with a threshold of rapid growth at the rainfall frequencies of once in every 50 years, but there is a limit. The improved understanding of the impact of landslides on the hydrologic response in Jianpinggou catchment provides valuable theoretical support for the storm flood forecast.

  12. Application and evaluation of a rapid response earthquake-triggered landslide model to the 25 April 2015 Mw 7.8 Gorkha earthquake, Nepal

    Gallen, Sean F.; Clark, Marin K.; Godt, Jonathan W.; Roback, Kevin; Niemi, Nathan A

    2017-01-01

    The 25 April 2015 Mw 7.8 Gorkha earthquake produced strong ground motions across an approximately 250 km by 100 km swath in central Nepal. To assist disaster response activities, we modified an existing earthquake-triggered landslide model based on a Newmark sliding block analysis to estimate the extent and intensity of landsliding and landslide dam hazard. Landslide hazard maps were produced using Shuttle Radar Topography Mission (SRTM) digital topography, peak ground acceleration (PGA) information from the U.S. Geological Survey (USGS) ShakeMap program, and assumptions about the regional rock strength based on end-member values from previous studies. The instrumental record of seismicity in Nepal is poor, so PGA estimates were based on empirical Ground Motion Prediction Equations (GMPEs) constrained by teleseismic data and felt reports. We demonstrate a non-linear dependence of modeled landsliding on aggregate rock strength, where the number of landslides decreases exponentially with increasing rock strength. Model estimates are less sensitive to PGA at steep slopes (> 60°) compared to moderate slopes (30–60°). We compare forward model results to an inventory of landslides triggered by the Gorkha earthquake. We show that moderate rock strength inputs over estimate landsliding in regions beyond the main slip patch, which may in part be related to poorly constrained PGA estimates for this event at far distances from the source area. Directly above the main slip patch, however, the moderate strength model accurately estimates the total number of landslides within the resolution of the model (landslides ≥ 0.0162 km2; observed n = 2214, modeled n = 2987), but the pattern of landsliding differs from observations. This discrepancy is likely due to the unaccounted for effects of variable material strength and local topographic amplification of strong ground motion, as well as other simplifying assumptions about source characteristics and their

  13. Landslides and the Fault Surface Ruptures during the 2008 Wengchuan Earthquake, Sichuan, China

    NASA Astrophysics Data System (ADS)

    Chigira, M.; Xiyong, Wu; Takashi, Inokuchi; Gonghui, Wang

    2009-04-01

    2008 Sichuan earthquake with a magnitude of Mw 7.9 induced numerous mass movements around the fault surface ruptures of which maximum separations we observed were 3.6 m vertical and 1.5 m horizontal (right lateral). In order to clarify the distribution of these landslides and to characterize them, we interpreted satellite images and made field investigation for 3 weeks by using these images. We used satellite ALOS images taken by the sensors AVNIR II with a resolution of 10 m and PRISM with a resolution of 2.5 m, both of which were taken on 4th in June. We also used satellite images of before and after the earthquake provided by Google Earth. The affected area was mountainous areas with elevations from 1000 m to 4500 m on the west of the Sichuan Basin. Ridges and valleys are generally trending NE parallel to the trends of the geologic structures, while large rivers, such as the Minjiang River, and the Fujiang River are flowing from the north or northwest to the south or southeast, crossing these trends. The NE-trending Longmenshan fault zone runs along the boundary between the mountains and the Sichuan basin (He and Tsukuda, 2003), of which Yinghsiuwan-Beichuan fault was the main fault that generated the 2008 earthquake (Xu, 2008). The basement rocks of the mountainous areas range from Precambrian to Cretaceous in age. They are basaltic rocks, granite, phyllite, dolostone, limestone, alternating beds of sandstone and shale, etc. (Geologic map of China). Landslide distribution areas were mainly of two types: One was the area along the fault that generated this earthquake, and another was along the steep slopes of inner valleys along the Minjian River. Landslides were concentrated on the hanging wall of the earthquake fault, which appeared for more than 180 km along the Longmenshan fault zone. The distribution area of landslides was wider around the middle and the southwest parts of the surface rupture trace and became narrower to the northeast. The directions of the

  14. Dilution of 10Be in detrital quartz by earthquake-induced landslides: Implications for determining denudation rates and potential to provide insights into landslide sediment dynamics

    NASA Astrophysics Data System (ADS)

    West, A. Joshua; Hetzel, Ralf; Li, Gen; Jin, Zhangdong; Zhang, Fei; Hilton, Robert G.; Densmore, Alexander L.

    2014-06-01

    The concentration of 10Be in detrital quartz (10Beqtz) from river sediments is now widely used to quantify catchment-wide denudation rates but may also be sensitive to inputs from bedrock landslides that deliver sediment with low 10Beqtz. Major landslide-triggering events can provide large amounts of low-concentration material to rivers in mountain catchments, but changes in river sediment 10Beqtz due to such events have not yet been measured directly. Here we examine the impact of widespread landslides triggered by the 2008 Wenchuan earthquake on 10Beqtz in sediment samples from the Min Jiang river basin, in Sichuan, China. Landslide deposit material associated with the Wenchuan earthquake has consistently lower 10Beqtz than in river sediment prior to the earthquake. River sediment 10Beqtz decreased significantly following the earthquake downstream of areas of high coseismic landslide occurrence (i.e., with greater than ∼0.3% of the upstream catchment area affected by landslides), because of input of the 10Be-depleted landslide material, but showed no systematic changes where landslide occurrence was low. Changes in river sediment 10Beqtz concentration were largest in small first-order catchments but were still significant in large river basins with areas of 104-105 km. Spatial and temporal variability in river sediment 10Beqtz has important implications for inferring representative denudation rates in tectonically active, landslide-dominated environments, even in large basins. Although the dilution of 10Beqtz in river sediment by landslide inputs may complicate interpretation of denudation rates, it also may provide a possible opportunity to track the transport of landslide sediment. The associated uncertainties are large, but in the Wenchuan case, calculations based on 10Be mixing proportions suggest that river sediment fluxes in the 2-3 years following the earthquake increased by a similar order of magnitude in the 0.25-1 mm and the <0.25 mm size fractions

  15. Susceptibility assessment of earthquake-triggered landslides in El Salvador using logistic regression

    NASA Astrophysics Data System (ADS)

    García-Rodríguez, M. J.; Malpica, J. A.; Benito, B.; Díaz, M.

    2008-03-01

    This work has evaluated the probability of earthquake-triggered landslide occurrence in the whole of El Salvador, with a Geographic Information System (GIS) and a logistic regression model. Slope gradient, elevation, aspect, mean annual precipitation, lithology, land use, and terrain roughness are the predictor variables used to determine the dependent variable of occurrence or non-occurrence of landslides within an individual grid cell. The results illustrate the importance of terrain roughness and soil type as key factors within the model — using only these two variables the analysis returned a significance level of 89.4%. The results obtained from the model within the GIS were then used to produce a map of relative landslide susceptibility.

  16. Comparison of the Structurally Controlled Landslides Numerical Model Results to the M 7.2 2013 Bohol Earthquake Co-seismic Landslides

    NASA Astrophysics Data System (ADS)

    Macario Galang, Jan Albert; Narod Eco, Rodrigo; Mahar Francisco Lagmay, Alfredo

    2015-04-01

    The M 7.2 October 15, 2013 Bohol earthquake is the most destructive earthquake to hit the Philippines since 2012. The epicenter was located in Sagbayan municipality, central Bohol and was generated by a previously unmapped reverse fault called the "Inabanga Fault". Its name, taken after the barangay (village) where the fault is best exposed and was first seen. The earthquake resulted in 209 fatalities and over 57 billion USD worth of damages. The earthquake generated co-seismic landslides most of which were related to fault structures. Unlike rainfall induced landslides, the trigger for co-seismic landslides happen without warning. Preparedness against this type of landslide therefore, relies heavily on the identification of fracture-related unstable slopes. To mitigate the impacts of co-seismic landslide hazards, morpho-structural orientations or discontinuity sets were mapped in the field with the aid of a 2012 IFSAR Digital Terrain Model (DTM) with 5-meter pixel resolution and < 0.5 meter vertical accuracy. Coltop 3D software was then used to identify similar structures including measurement of their dip and dip directions. The chosen discontinuity sets were then keyed into Matterocking software to identify potential rock slide zones due to planar or wedged discontinuities. After identifying the structurally-controlled unstable slopes, the rock mass propagation extent of the possible rock slides was simulated using Conefall. The results were compared to a post-earthquake landslide inventory of 456 landslides. Out the total number of landslides identified from post-earthquake high-resolution imagery, 366 or 80% intersect the structural-controlled hazard areas of Bohol. The results show the potential of this method to identify co-seismic landslide hazard areas for disaster mitigation. Along with computer methods to simulate shallow landslides, and debris flow paths, located structurally-controlled unstable zones can be used to mark unsafe areas for settlement. The

  17. The Geometric Characteristics and Initiation Mechanisms of the Earthquake- Triggered Daguangbao Landslide

    NASA Astrophysics Data System (ADS)

    Dong, J. J.; Tsao, C. C.; Yang, C. M.; Wu, W. J.; Lee, C. T.; Lin, M. L.; Zhang, W. F.; Pei, X. J.; Wang, G. H.; Huang, R.

    2014-12-01

    Recently, catastrophic landslides are getting considerable attentions not only from natural hazard but also from geo-material science. In the past century, the Daguangbao (DGB) landslide which triggered by the Wenchuan earthquake is one of the largest earthquake- triggered landslides. Our main goal is to characterize the geometry of DGB landslide to better determine the initiation mechanisms. Based on the remote sensing images analysis and field investigation, we proposed an atypical wedge model of DGB landslide compose of a folded strata and a zigzag stepping-out joint system, which outcropped at the south and north of the landslide site, respectively. The intersection line of wedge is curved, counterclockwise rotated and daylighted, which fit the pre- and post- position of the mining tent with 1.9 km displacements. The volume of sliding mass was evaluated to 10.51×108 m3 by the atypical wedge model. The identified slip zone of DGB landslide consists of the breccia and gouge layers in the dolomite strata. The rotary-shear tests were performed with the intact dolomite rocks near the slip zone and the gouges in the slip zone to determine the strength of slip surface. The peak and the steady-state friction coefficient of the tested dry dolomite discontinuities, wet gouges are 0.52~0.96, 0.73~0.86 and 0.1~0.57, 0.16~0.63, respectively. Although the result of static wedge stability analysis shows that the slope is quite stable (F.S. = 4), but the result of pseudo-static wedge stability analysis with seismic coefficient will trigger the gigantic wedge by the Wenchuan earthquake. Moreover, the friction coefficient of the tested gouges after long slip displacements as shear velocity exceeds 1.3 m/s will lower than 0.25 (=tan(14°); the intersection line plunged 14°). Therefore, the gigantic wedge can be accelerated by the inertial force and keep moving rapidly with long run-out. According to the calculations of simple one dimensional particle motion model, DGB landslide

  18. Landslides and vegetation cover in the 2005 North Pakistan earthquake: a GIS and statistical quantitative approach

    NASA Astrophysics Data System (ADS)

    Peduzzi, P.

    2010-04-01

    The growing concern for loss of services once provided by natural ecosystems is getting increasing attention. However, the accelerating rate of natural resources destruction calls for rapid and global action. With often very limited budgets, environmental agencies and NGOs need cost-efficient ways to quickly convince decision-makers that sound management of natural resources can help to protect human lives and their welfare. The methodology described in this paper, is based on geospatial and statistical analysis, involving simple Geographical Information System (GIS) and remote sensing algorithms. It is based on free or very low-cost data. It aims to scientifically assess the potential role of vegetation in mitigating landslides triggered by earthquakes by normalising for other factors such as slopes and distance from active fault. The methodology was applied to the 2005 North Pakistan/India earthquake which generated a large number of victims and hundreds of landslides. The study shows that if slopes and proximity from active fault are the main susceptibility factors for post landslides triggered by earthquakes in this area, the results clearly revealed that areas covered by denser vegetation suffered less and smaller landslides than areas with thinner (or devoid of) vegetation cover. Short distance from roads/trails and rivers also proved to be pertinent factors in increasing landslides susceptibility. This project is a component of a wider initiative involving the Global Resource Information Database Europe from the United Nations Environment Programme, the International Union for Conservation of Nature, the Institute of Geomatics and Risk Analysis from the University of Lausanne and the "institut universitaire d'études du développement" from the University of Geneva.

  19. Relation of landslides triggered by the Kiholo Bay earthquake to modeled ground motion

    Harp, Edwin L.; Hartzell, Stephen H.; Jibson, Randall W.; Ramirez-Guzman, L.; Schmitt, Robert G.

    2014-01-01

    The 2006 Kiholo Bay, Hawaii, earthquake triggered high concentrations of rock falls and slides in the steep canyons of the Kohala Mountains along the north coast of Hawaii. Within these mountains and canyons a complex distribution of landslides was triggered by the earthquake shaking. In parts of the area, landslides were preferentially located on east‐facing slopes, whereas in other parts of the canyons no systematic pattern prevailed with respect to slope aspect or vertical position on the slopes. The geology within the canyons is homogeneous, so we hypothesize that the variable landslide distribution is the result of localized variation in ground shaking; therefore, we used a state‐of‐the‐art, high‐resolution ground‐motion simulation model to see if it could reproduce the landslide‐distribution patterns. We used a 3D finite‐element analysis to model earthquake shaking using a 10 m digital elevation model and slip on a finite‐fault model constructed from teleseismic records of the mainshock. Ground velocity time histories were calculated up to a frequency of 5 Hz. Dynamic shear strain also was calculated and compared with the landslide distribution. Results were mixed for the velocity simulations, with some areas showing correlation of landslide locations with peak modeled ground motions but many other areas showing no such correlation. Results were much improved for the comparison with dynamic shear strain. This suggests that (1) rock falls and slides are possibly triggered by higher frequency ground motions (velocities) than those in our simulations, (2) the ground‐motion velocity model needs more refinement, or (3) dynamic shear strain may be a more fundamental measurement of the decoupling process of slope materials during seismic shaking.

  20. Structural controls on the large landslides triggered by the 14 November 2016, MW 7.8 Earthquake, Kaikoura, New Zealand

    NASA Astrophysics Data System (ADS)

    Massey, Chris

    2017-04-01

    The Kaikoura earthquake generated tens of thousands of landslides over a total area of about 10,000 km2, with the majority concentrated in a smaller area of about 3,500 km2. A noteworthy aspect of this event is the large number of landslides that occurred on the steep coastal cliffs south of Ward and extending to Oaro, north of Christchurch, which led to the closure of state highway routes. Another noteworthy feature of this earthquake is the large number (more than 190) of valley blocking landslides it generated. This was partly due to the presence of steep and confined slopes in areas of strong ground shaking. The largest valley blocking landslide has an approximate volume of 12(±2) M m3 and the debris travelled about 2.7 km down slope forming a dam on the Hapuku River. Given the sparse population in the vicinity of the landslides, only a few homes were impacted and there were no recorded deaths due to landslides. However, the long-term stability of cracked slopes and landslide "dams" from future strong earthquakes and significant rain events are an ongoing concern to central and local government agencies responsible for rebuilding homes and infrastructure. A particular concern is the potential for debris floods to affect downstream residences and infrastructure should some of the landslide dams breach catastrophically. The mapped landslide distribution reflects the complexity of the earthquake rupture—at least 13 faults ruptured to the ground surface or sea floor. The majority of landslides occurred in two geological and geotechnically distinct materials: Neogene sedimentary rocks (sandstones, limestones and siltstones) where first-time and reactivated rock-slides were the dominant landslide type, and Torlesse "basement" rocks (greywacke sandstones and argillite) where first-time rock and debris avalanches dominated. The largest landslides triggered by the earthquake are located either on or adjacent to faults that ruptured to the ground surface and so they

  1. Are landslides in the New Madrid Seismic Zone the result of the 1811-1812 earthquake sequence or multiple prehistoric earthquakes?

    NASA Astrophysics Data System (ADS)

    Gold, Ryan; Williams, Robert; Jibson, Randall

    2014-05-01

    Previous research indicates that deep translational and rotational landslides along the bluffs east of the Mississippi River in western Tennessee were triggered by the M7-8 1811-1812 New Madrid earthquake sequence. Analysis of recently acquired airborne LiDAR data suggests the possibility of multiple generations of landslides, possibly triggered by older, similar magnitude earthquake sequences, which paleoliquifaction studies show occurred circa 1450 and about 900 A.D. Using these LiDAR data, we have remapped recent landslides along two sections of the bluffs: a northern section near Reelfoot Lake and a southern section near Meeman-Shelby State Park (20 km north of Memphis, Tennessee). The bare-earth, digital-elevation models derived from these LiDAR data have a resolution of 0.5 m and reveal valuable details of topography given the region's dense forest canopy. Our mapping confirms much of the previous landslide mapping, refutes a few previously mapped landslides, and reveals new, undetected landslides. Importantly, we observe that the landslide deposits in the Reelfoot region are characterized by rotated blocks with sharp uphill-facing scarps and steep headwall scarps, indicating youthful, relatively recent movement. In comparison, landslide deposits near Meeman-Shelby are muted in appearance, with headwall scarps and rotated blocks that are extensively dissected by gullies, indicating they might be an older generation of landslides. Because of these differences in morphology, we hypothesize that the landslides near Reelfoot Lake were triggered by the 1811-1812 earthquake sequence and that landslides near Meeman-Shelby resulted from shaking associated with earlier earthquake sequences. To test this hypothesis, we will evaluate differences in bluff height, local geology, vegetation, and proximity to known seismic sources. Furthermore, planned fieldwork will help evaluate whether the observed landslide displacements occurred in single earthquakes or if they might

  2. Causes of unusual distribution of coseismic landslides triggered by the Mw 6.1 2014 Ludian, Yunnan, China earthquake

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-li; Liu, Chun-guo; Wang, Ming-ming; Zhou, Qing

    2018-06-01

    The Mw 6.1 2014 Ludian, Yunnan, China earthquake triggered numerous coseismic landslides that do not appear to be associated with any previously known seismogenic fault. Traditional models of triggering for seismically generated landslides do not provide a reasonable explanation for the landslide pattern observed here. Here the Newmark method is applied to a grid to calculate the minimum accelerations required for slope failures throughout the affected region. The results demonstrate that for much of the study area, the distribution of failure prone slopes is similar to the actual pattern of coseismic landslides, however there are some areas where the model predicts considerably fewer failures than occurred. We suggest that this is a result of the complex source faults that generated the Ludian earthquake, which produced a half-conjugate rupture on nearly EW- and NNW trending faults at depth. The rupture directed much of its seismic moment southeast of the epicenter, increasing ground shaking and the number of resulting landslides.

  3. Landslides triggered by the 12 January 2010 Mw 7.0 Port-au-Prince, Haiti, earthquake: visual interpretation, inventory compiling and spatial distribution statistical analysis

    NASA Astrophysics Data System (ADS)

    Xu, C.; Shyu, J. B. H.; Xu, X.-W.

    2014-02-01

    The 12 January 2010 Port-au-Prince, Haiti, earthquake (Mw 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate the correlations of the occurrence of landslides and their erosion thicknesses with topographic factors, seismic parameters, and their distance from roads. A total of 30 828 landslides triggered by the earthquake covered a total area of 15.736 km2, distributed in an area more than 3000 km2, and the volume of landslide accumulation materials is estimated to be about 29 700 000 m3. These landslides are of various types, mostly belonging to shallow disrupted landslides and rock falls, but also include coherent deep-seated landslides and rock slides. These landslides were delineated using pre- and post-earthquake high-resolutions satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were constructed in order to analyze the spatial distribution patterns of co-seismic landslides. Statistics of size distribution and morphometric parameters of co-seismic landslides were carried out and were compared with other earthquake events in the world. Four proxies of co-seismic landslide abundance, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate co-seismic landslides with various landslide controlling parameters. These controlling parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, lithology, distance from the epicenter, distance from the Enriquillo-Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). A comparison of these impact parameters on co-seismic landslides shows that slope angle is the strongest impact parameter on co-seismic landslide occurrence. Our co-seismic landslide inventory is much more

  4. Vegetation recovery patterns assessment at landslides caused by catastrophic earthquake: a case study in central Taiwan.

    PubMed

    Chou, Wen-Chieh; Lin, Wen-Tzu; Lin, Chao-Yuan

    2009-05-01

    The catastrophic earthquake, 7.3 on the Richter scale, occurred on September 21, 1999 in Central Taiwan. Much of standing vegetation on slopes was eliminated and massive, scattered landslides were induced at the Jou-Jou Mountain area of the Wu-Chi basin in Nantou County. We evaluated three methods for assessing landslide hazard and vegetation recovery conditions. (1) Self-organizing map (SOM) neural network coupled with fuzzy technique was used to quickly extract the landslide. (2) The NDVI-based vegetation recovery index derived from multi-temporal SPOT satellite images was used to evaluate vegetation recovery rate in the denudation sites. (3) The spatial distribution index (SDI) based on land-cover topographic location was employed to analyze vegetation recovery patterns, including the invading, surviving and mixed patterns at the Jou-Jou Mountain area. On September 27, 1999, there were 849.20 ha of landslide area extracted using the self-organizing map and fuzzy technique combined model. After six years of natural vegetation succession, the landslide has gradually restored, and vegetation recovery rate reached up to 86%. On-site observation shows that many native pioneer plants have invaded onto the denudation sites even if disturbed by several typhoons. Two native surviving plants, Arundo formosana Hack and Pinus taiwanensis Hayata, play a vital role in natural vegetation succession in this area, especially for the sites on ridgeline and steep slopes.

  5. Possible Dual Earthquake-Landslide Source of the 13 November 2016 Kaikoura, New Zealand Tsunami

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, Mohammad; Satake, Kenji

    2017-10-01

    A complicated earthquake ( M w 7.8) in terms of rupture mechanism occurred in the NE coast of South Island, New Zealand, on 13 November 2016 (UTC) in a complex tectonic setting comprising a transition strike-slip zone between two subduction zones. The earthquake generated a moderate tsunami with zero-to-crest amplitude of 257 cm at the near-field tide gauge station of Kaikoura. Spectral analysis of the tsunami observations showed dual peaks at 3.6-5.7 and 5.7-56 min, which we attribute to the potential landslide and earthquake sources of the tsunami, respectively. Tsunami simulations showed that a source model with slip on an offshore plate-interface fault reproduces the near-field tsunami observation in terms of amplitude, but fails in terms of tsunami period. On the other hand, a source model without offshore slip fails to reproduce the first peak, but the later phases are reproduced well in terms of both amplitude and period. It can be inferred that an offshore source is necessary to be involved, but it needs to be smaller in size than the plate interface slip, which most likely points to a confined submarine landslide source, consistent with the dual-peak tsunami spectrum. We estimated the dimension of the potential submarine landslide at 8-10 km.

  6. SLAMMER: Seismic LAndslide Movement Modeled using Earthquake Records

    Jibson, Randall W.; Rathje, Ellen M.; Jibson, Matthew W.; Lee, Yong W.

    2013-01-01

    This program is designed to facilitate conducting sliding-block analysis (also called permanent-deformation analysis) of slopes in order to estimate slope behavior during earthquakes. The program allows selection from among more than 2,100 strong-motion records from 28 earthquakes and allows users to add their own records to the collection. Any number of earthquake records can be selected using a search interface that selects records based on desired properties. Sliding-block analyses, using any combination of rigid-block (Newmark), decoupled, and fully coupled methods, are then conducted on the selected group of records, and results are compiled in both graphical and tabular form. Simplified methods for conducting each type of analysis are also included.

  7. Volcanic tremor and local earthquakes at Copahue volcanic complex, Southern Andes, Argentina

    NASA Astrophysics Data System (ADS)

    Ibáñez, J. M.; Del Pezzo, E.; Bengoa, C.; Caselli, A.; Badi, G.; Almendros, J.

    2008-07-01

    In the present paper we describe the results of a seismic field survey carried out at Copahue Volcano, Southern Andes, Argentina, using a small-aperture, dense seismic antenna. Copahue Volcano is an active volcano that exhibited a few phreatic eruptions in the last 20 years. The aim of this experiment was to record and classify the background seismic activity of this volcanic area, and locate the sources of local earthquakes and volcanic tremor. Data consist of several volcano-tectonic (VT) earthquakes, and many samples of back-ground seismic noise. We use both ordinary spectral, and multi-spectral techniques to measure the spectral content, and an array technique [Zero Lag Cross Correlation technique] to measure the back-azimuth and apparent slowness of the signals propagating across the array. We locate VT earthquakes using a procedure based on the estimate of slowness vector components and S-P time. VT events are located mainly along the border of the Caviahue caldera lake, positioned at the South-East of Copahue volcano, in a depth interval of 1-3 km below the surface. The background noise shows the presence of many transients with high correlation among the array stations in the frequency band centered at 2.5 Hz. These transients are superimposed to an uncorrelated background seismic signal. Array solutions for these transients show a predominant slowness vector pointing to the exploited geothermal field of "Las Maquinitas" and "Copahue Village", located about 6 km north of the array site. We interpret this coherent signal as a tremor generated by the activity of the geothermal field.

  8. The size, distribution, and mobility of landslides caused by the 2015 Mw7.8 Gorkha earthquake, Nepal

    NASA Astrophysics Data System (ADS)

    Roback, Kevin; Clark, Marin K.; West, A. Joshua; Zekkos, Dimitrios; Li, Gen; Gallen, Sean F.; Chamlagain, Deepak; Godt, Jonathan W.

    2018-01-01

    Coseismic landslides pose immediate and prolonged hazards to mountainous communities, and provide a rare opportunity to study the effect of large earthquakes on erosion and sediment budgets. By mapping landslides using high-resolution satellite imagery, we find that the 25 April 2015 Mw7.8 Gorkha earthquake and aftershock sequence produced at least 25,000 landslides throughout the steep Himalayan Mountains in central Nepal. Despite early reports claiming lower than expected landslide activity, our results show that the total number, area, and volume of landslides associated with the Gorkha event are consistent with expectations, when compared to prior landslide-triggering earthquakes around the world. The extent of landsliding mimics the extent of fault rupture along the east-west trace of the Main Himalayan Thrust and increases eastward following the progression of rupture. In this event, maximum modeled Peak Ground Acceleration (PGA) and the steepest topographic slopes of the High Himalaya are not spatially coincident, so it is not surprising that landslide density correlates neither with PGA nor steepest slopes on their own. Instead, we find that the highest landslide density is located at the confluence of steep slopes, high mean annual precipitation, and proximity to the deepest part of the fault rupture from which 0.5-2 Hz seismic energy originated. We suggest that landslide density was determined by a combination of earthquake source characteristics, slope distributions, and the influence of precipitation on rock strength via weathering and changes in vegetation cover. Determining the relative contribution of each factor will require further modeling and better constrained seismic parameters, both of which are likely to be developed in the coming few years as post-event studies evolve. Landslide mobility, in terms of the ratio of runout distance to fall height, is comparable to small volume landslides in other settings, and landslide volume-runout scaling is

  9. The size, distribution, and mobility of landslides caused by the 2015 Mw7.8 Gorkha earthquake, Nepal

    Roback, Kevin; Clark, Marin K.; West, A. Joshua; Zekkos, Dimitrios; Li, Gen; Gallen, Sean F.; Chamlagain, Deepak; Godt, Jonathan W.

    2018-01-01

    Coseismic landslides pose immediate and prolonged hazards to mountainous communities, and provide a rare opportunity to study the effect of large earthquakes on erosion and sediment budgets. By mapping landslides using high-resolution satellite imagery, we find that the 25 April 2015 Mw7.8 Gorkha earthquake and aftershock sequence produced at least 25,000 landslides throughout the steep Himalayan Mountains in central Nepal. Despite early reports claiming lower than expected landslide activity, our results show that the total number, area, and volume of landslides associated with the Gorkha event are consistent with expectations, when compared to prior landslide-triggering earthquakes around the world. The extent of landsliding mimics the extent of fault rupture along the east-west trace of the Main Himalayan Thrust and increases eastward following the progression of rupture. In this event, maximum modeled Peak Ground Acceleration (PGA) and the steepest topographic slopes of the High Himalaya are not spatially coincident, so it is not surprising that landslide density correlates neither with PGA nor steepest slopes on their own. Instead, we find that the highest landslide density is located at the confluence of steep slopes, high mean annual precipitation, and proximity to the deepest part of the fault rupture from which 0.5–2 Hz seismic energy originated. We suggest that landslide density was determined by a combination of earthquake source characteristics, slope distributions, and the influence of precipitation on rock strength via weathering and changes in vegetation cover. Determining the relative contribution of each factor will require further modeling and better constrained seismic parameters, both of which are likely to be developed in the coming few years as post-event studies evolve. Landslide mobility, in terms of the ratio of runout distance to fall height, is comparable to small volume landslides in other settings, and landslide volume-runout scaling

  10. Export of earthquake-triggered landslides in active mountain ranges: insights from 2D morphodynamic modelling.

    NASA Astrophysics Data System (ADS)

    Croissant, Thomas; Lague, Dimitri; Davy, Philippe; Steer, Philippe

    2016-04-01

    In active mountain ranges, large earthquakes (Mw > 5-6) trigger numerous landslides that impact river dynamics. These landslides bring local and sudden sediment piles that will be eroded and transported along the river network causing downstream changes in river geometry, transport capacity and erosion efficiency. The progressive removal of landslide materials has implications for downstream hazards management and also for understanding landscape dynamics at the timescale of the seismic cycle. The export time of landslide-derived sediments after large-magnitude earthquakes has been studied from suspended load measurements but a full understanding of the total process, including the coupling between sediment transfer and channel geometry change, still remains an issue. Note that the transport of small sediment pulses has been studied in the context of river restoration, but the magnitude of sediment pulses generated by landslides may make the problem different. Here, we study the export of large volumes (>106 m3) of sediments with the 2D hydro-morphodynamic model, Eros. This model uses a new hydrodynamic module that resolves a reduced form of the Saint-Venant equations with a particle method. It is coupled with a sediment transport and lateral and vertical erosion model. Eros accounts for the complex retroactions between sediment transport and fluvial geometry, with a stochastic description of the floods experienced by the river. Moreover, it is able to reproduce several features deemed necessary to study the evacuation of large sediment pulses, such as river regime modification (single-thread to multi-thread), river avulsion and aggradation, floods and bank erosion. Using a synthetic and simple topography we first present how granulometry, landslide volume and geometry, channel slope and flood frequency influence 1) the dominance of pulse advection vs. diffusion during its evacuation, 2) the pulse export time and 3) the remaining volume of sediment in the catchment

  11. The kinematics and initiation mechanisms of the earthquake-triggered Daguangbao landslide

    NASA Astrophysics Data System (ADS)

    Yang, Che-Ming; Cheng, Hui-Yun; Tsao, Chia-Che; Wu, Wen-Jie; Dong, Jia-Jyun; Lee, Chyi-Tyi; Lin, Ming-Lang; Zhang, Wei-Fong; Pei, Xiang-Jun; Wang, Gong-Hui; Huang, Run-Qiu

    2015-04-01

    The Daguangbao (DGB) landslide is one of the largest earthquake-triggered landslides induced by the 2008 Wenchuan earthquake in the world over the past century. Based on remote sensing images, topography analysis and field investigation, this landslide was speculated a gigantic atypical wedge failure with the folded bedding plane and a zigzag stepping-out joint system, which outcropped at the south and north, respectively. With the inferred failure surfaces, the volume of the DGB landslide is about 1,051 Mm3. The frequently adopted Rigid Wedge Method (RWM), which assumed zero shear stress on the sliding surface along the vectors perpendicular to the intersection line when evaluating the wedge stability, could not be valid for this super large DGB wedge. Under an assumption that the shear strength is fully mobilized on the sliding surface along the vectors perpendicular to the intersection line, this study proposed to use a Maximum Shear Stress Method (MSSM) to calculate the factor of safety (FOS) of the DGB wedge. Based on the assumptions of the two methods, the FOS of the RWM and MSSM are the upper and lower bounds for the wedge stability analysis. Based on the rotary shear tests, the averaged friction coefficients of the representative materials of the two sliding surfaces are 0.79 (bedding parallel fault gauges) and 0.71 (dolomite joints). Without external force, the FOSs of the DGB landslide are 4.14 and 2.51 by the RWM and MSSM, respectively. Restate, the wedge is stable before the 2008 Wenchuan earthquake. However, DGB landslide can be triggered at 35.7 sec based on the ground acceleration records of strong motion station MZQP during the 2008 Wenchuan earthquake and the pseudo-static stability analysis incorporated into MSSM (Acceleration: EW=0.272g, NS=0.152g, Vertical=0.244g). Moreover, using the friction coefficient of the representative materials under large shear displacement under shear velocity of 1.3 m/s (0.16 for bedding parallel fault gouges and 0

  12. Earthquake induced landslide hazard: a multidisciplinary field observatory in the Marmara SUPERSITE

    NASA Astrophysics Data System (ADS)

    Bigarré, Pascal

    2014-05-01

    Earthquake-triggered landslides have an increasing disastrous impact in seismic regions due to the fast growing urbanization and infrastructures. Just considering disasters from the last fifteen years, among which the 1999 Chi-Chi earthquake, the 2008 Wenchuan earthquake, and the 2011 Tohoku earthquake, these events generated tens of thousands of coseismic landslides. Those resulted in amazing death toll and considerable damages, affecting the regional landscape including its hydrological main features. Despite a strong impetus in research during past decades, knowledge on those geohazards is still fragmentary, while databases of high quality observational data are lacking. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. As one of the three SUPERSITE concept FP7 projects dealing with long term high level monitoring of major natural hazards at the European level, the MARSITE project gathers research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Besides the seismic threat, landslides in Turkey and in this region constitute an important source of loss. The 1999 Earthquake caused extensive landslides while tsunami effects were observed during the post-event surveys in several places along the coasts of the Izmit bay. The 6th Work Package of MARSITE project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest. First, the Cekmece-Avcilar peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake

  13. Landslides triggered by the 12 January 2010 Port-au-Prince, Haiti, Mw = 7.0 earthquake: visual interpretation, inventory compiling, and spatial distribution statistical analysis

    NASA Astrophysics Data System (ADS)

    Xu, C.; Shyu, J. B. H.; Xu, X.

    2014-07-01

    The 12 January 2010 Port-au-Prince, Haiti, earthquake (Mw= 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate the correlations of the occurrence of landslides and the thicknesses of their erosion with topographic, geologic, and seismic parameters. A total of 30 828 landslides triggered by the earthquake covered a total area of 15.736 km2, distributed in an area more than 3000 km2, and the volume of landslide accumulation materials is estimated to be about 29 700 000 m3. These landslides are of various types, mostly belonging to shallow disrupted landslides and rock falls, but also include coherent deep-seated landslides and rock slides. These landslides were delineated using pre- and post-earthquake high-resolution satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were constructed in order to analyze the spatial distribution patterns of co-seismic landslides. Statistics of size distribution and morphometric parameters of co-seismic landslides were carried out and were compared with other earthquake events in the world. Four proxies of co-seismic landslide abundance, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate co-seismic landslides with various environmental parameters. These parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, lithology, distance from the epicenter, distance from the Enriquillo-Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). A comparison of these impact parameters on co-seismic landslides shows that slope angle is the strongest impact parameter on co-seismic landslide occurrence. Our co-seismic landslide inventory is much more detailed than other inventories in several

  14. Landslide!

    ERIC Educational Resources Information Center

    Hall-Wallace, Michelle; Mitchell, Carl

    1996-01-01

    Presents a unit that focuses on landslides and integrates earth science, physics, chemistry, and math. Includes activities to investigate porosity, permeability, cohesion, saturation, and gravity. (JRH)

  15. Geological Investigation and analysis in response to Earthquake Induced Landslide in West Sumatra

    NASA Astrophysics Data System (ADS)

    Karnawati, D.; Wilopo, W.; Salahudin, S.; Sudarno, I.; Burton, P.

    2009-12-01

    Substantial socio-economical loss occurred in response to the September 30. 2009 West Sumatra Earthquake with magnitude of 7.6. Damage of houses and engineered structures mostly occurred at the low land of alluvium sediments due to the ground amplification, whilst at the high land of mountain slopes several villages were buried by massive debris of rocks and soils. It was recorded that 1115 people died due to this disasters. Series of geological investigation was carried out by Geological Engineering Department of Gadjah Mada University, with the purpose to support the rehabilitation program. Based on this preliminary investigation it was identified that most of the house and engineered structural damages at the alluvial deposits mainly due to by the poor quality of such houses and engineered structures, which poorly resist the ground amplification, instead of due to the control of geological conditions. On the other hand, the existence and distribution of structural geology (faults and joints) at the mountaineous regions are significant in controlling the distribution of landslides, with the types of rock falls, debris flows and debris falls. Despite the landslide susceptibility mapping conducted by Geological Survey of Indonesia, more detailed investigation is required to be carried out in the region surrounding Maninjau Lake, in order to provide safer places for village relocation. Accordingly Gadjah Mada University in collaboration with the local university (Andalas University) as well as with the local Government of Agam Regency and the Geological Survey of Indonesia, serve the mission for conducting rather more detailed geological and landslide investigation. It is also crucial that the investigation (survey and mapping) on the social perception and expectation of local people living in this landslide susceptible area should also be carried out, to support the mitigation effort of any future potential earthquake induced landslides.

  16. Scenario-Based Tsunami Hazard Assessment from Earthquake and Landslide Sources for Eastern Sicily, Italy

    NASA Astrophysics Data System (ADS)

    Tinti, S.; Armigliato, A.; Pagnoni, G.; Paparo, M. A.; Zaniboni, F.

    2016-12-01

    Eastern Sicily was theatre of the most damaging tsunamis that ever struck Italy, such as the 11 January 1693 and the 28 December 1908 tsunamis. Tectonic studies and paleotsunami investigations extended historical records of tsunami occurrence back of several thousands of years. Tsunami sources relevant for eastern Sicily are both local and remote, the latter being located in the Ionian Greece and in the Western Hellenic Arc. Here in 365 A.D. a large earthquake generated a tsunami that was seen in the whole eastern and central Mediterranean including the Sicilian coasts. The objective of this study is the evaluation of tsunami hazard along the coast of eastern Sicily, central Mediterranean, Italy via a scenario-based technique, which has been preferred to the PTHA approach because, when dealing with tsunamis induced by landslides, uncertainties are usually so large to undermine the PTHA results. Tsunamis of earthquake and landslide origin are taken into account for the entire coast of Sicily, from the Messina to the Siracusa provinces. Landslides are essentially local sources and can occur underwater along the unstable flanks of the Messina Straits or along the steep slopes of the Hyblaean-Malta escarpment. The method is based on a two-step procedure. After a preliminary step where very many earthquake and landslide sources are taken into account and tsunamis are computed on a low-resolution grid, the worst-case scenarios are selected and tsunamis are simulated on a finer-resolution grid allowing for a better calculation of coastal wave height and tsunami penetration. The final result of our study is given in the form of aggregate fields computed from individual scenarios. Also interesting is the contribution of the various tsunami sources in different localities along the coast. It is found that the places with the highest level of hazard are the low lands of La Playa south of Catania and of the Bay of Augusta, which is in agreement also with historical

  17. Analysis of landslide hazard area in Ludian earthquake based on Random Forests

    NASA Astrophysics Data System (ADS)

    Xie, J.-C.; Liu, R.; Li, H.-W.; Lai, Z.-L.

    2015-04-01

    With the development of machine learning theory, more and more algorithms are evaluated for seismic landslides. After the Ludian earthquake, the research team combine with the special geological structure in Ludian area and the seismic filed exploration results, selecting SLOPE(PODU); River distance(HL); Fault distance(DC); Seismic Intensity(LD) and Digital Elevation Model(DEM), the normalized difference vegetation index(NDVI) which based on remote sensing images as evaluation factors. But the relationships among these factors are fuzzy, there also exists heavy noise and high-dimensional, we introduce the random forest algorithm to tolerate these difficulties and get the evaluation result of Ludian landslide areas, in order to verify the accuracy of the result, using the ROC graphs for the result evaluation standard, AUC covers an area of 0.918, meanwhile, the random forest's generalization error rate decreases with the increase of the classification tree to the ideal 0.08 by using Out Of Bag(OOB) Estimation. Studying the final landslides inversion results, paper comes to a statistical conclusion that near 80% of the whole landslides and dilapidations are in areas with high susceptibility and moderate susceptibility, showing the forecast results are reasonable and adopted.

  18. Methodologies for the assessment of earthquake-triggered landslides hazard. A comparison of Logistic Regression and Artificial Neural Network models.

    NASA Astrophysics Data System (ADS)

    García-Rodríguez, M. J.; Malpica, J. A.; Benito, B.

    2009-04-01

    In recent years, interest in landslide hazard assessment studies has increased substantially. They are appropriate for evaluation and mitigation plan development in landslide-prone areas. There are several techniques available for landslide hazard research at a regional scale. Generally, they can be classified in two groups: qualitative and quantitative methods. Most of qualitative methods tend to be subjective, since they depend on expert opinions and represent hazard levels in descriptive terms. On the other hand, quantitative methods are objective and they are commonly used due to the correlation between the instability factors and the location of the landslides. Within this group, statistical approaches and new heuristic techniques based on artificial intelligence (artificial neural network (ANN), fuzzy logic, etc.) provide rigorous analysis to assess landslide hazard over large regions. However, they depend on qualitative and quantitative data, scale, types of movements and characteristic factors used. We analysed and compared an approach for assessing earthquake-triggered landslides hazard using logistic regression (LR) and artificial neural networks (ANN) with a back-propagation learning algorithm. One application has been developed in El Salvador, a country of Central America where the earthquake-triggered landslides are usual phenomena. In a first phase, we analysed the susceptibility and hazard associated to the seismic scenario of the 2001 January 13th earthquake. We calibrated the models using data from the landslide inventory for this scenario. These analyses require input variables representing physical parameters to contribute to the initiation of slope instability, for example, slope gradient, elevation, aspect, mean annual precipitation, lithology, land use, and terrain roughness, while the occurrence or non-occurrence of landslides is considered as dependent variable. The results of the landslide susceptibility analysis are checked using landslide

  19. Landslides

    2003-04-02

    The slumping of materials in the walls of this impact crater imaged by NASA Mars Odyssey spacecraft illustrates the continued erosion of the Martian surface. Small fans of debris as well as larger landslides are observed throughout the image.

  20. Assessment of existing and potential landslide hazards resulting from the April 25, 2015 Gorkha, Nepal earthquake sequence

    Collins, Brian D.; Jibson, Randall W.

    2015-07-28

    This report provides a detailed account of assessments performed in May and June 2015 and focuses on valley-blocking landslides because they have the potential to pose considerable hazard to many villages in Nepal. First, we provide a seismological background of Nepal and then detail the methods used for both external and in-country data collection and interpretation. Our results consist of an overview of landsliding extent, a characterization of all valley-blocking landslides identified during our work, and a description of video resources that provide high resolution coverage of approximately 1,000 kilometers (km) of river valleys and surrounding terrain affected by the Gorkha earthquake sequence. This is followed by a description of site-specific landslide-hazard assessments conducted while in Nepal and includes detailed descriptions of five noteworthy case studies. Finally, we assess the expectation for additional landslide hazards during the 2015 summer monsoon season.

  1. A relation to predict the failure of materials and potential application to volcanic eruptions and landslides

    PubMed Central

    Hao, Shengwang; Liu, Chao; Lu, Chunsheng; Elsworth, Derek

    2016-01-01

    A theoretical explanation of a time-to-failure relation is presented, with this relationship then used to describe the failure of materials. This provides the potential to predict timing (tf − t) immediately before failure by extrapolating the trajectory as it asymptotes to zero with no need to fit unknown exponents as previously proposed in critical power law behaviors. This generalized relation is verified by comparison with approaches to criticality for volcanic eruptions and creep failure. A new relation based on changes with stress is proposed as an alternative expression of Voight’s relation, which is widely used to describe the accelerating precursory signals before material failure and broadly applied to volcanic eruptions, landslides and other phenomena. The new generalized relation reduces to Voight’s relation if stress is limited to increase at a constant rate with time. This implies that the time-derivatives in Voight’s analysis may be a subset of a more general expression connecting stress derivatives, and thus provides a potential method for forecasting these events. PMID:27306851

  2. Prodigious submarine landslides during the inception and early growth of volcanic islands.

    PubMed

    Hunt, James E; Jarvis, Ian

    2017-12-12

    Volcanic island inception applies large stresses as the ocean crust domes in response to magma ascension and is loaded by eruption of lavas. There is currently limited information on when volcanic islands are initiated on the seafloor, and no information regarding the seafloor instabilities island inception may cause. The deep sea Madeira Abyssal Plain contains a 43 million year history of turbidites among which many originate from mass movements in the Canary Islands. Here, we investigate the composition and timing of a distinctive group of turbidites that we suggest represent a new unique record of large-volume submarine landslides triggered during the inception, submarine shield growth, and final subaerial emergence of the Canary Islands. These slides are predominantly multi-stage and yet represent among the largest mass movements on the Earth's surface up to three or more-times larger than subaerial Canary Islands flank collapses. Thus whilst these deposits provide invaluable information on ocean island geodynamics they also represent a significant, and as yet unaccounted, marine geohazard.

  3. A relation to predict the failure of materials and potential application to volcanic eruptions and landslides.

    PubMed

    Hao, Shengwang; Liu, Chao; Lu, Chunsheng; Elsworth, Derek

    2016-06-16

    A theoretical explanation of a time-to-failure relation is presented, with this relationship then used to describe the failure of materials. This provides the potential to predict timing (tf - t) immediately before failure by extrapolating the trajectory as it asymptotes to zero with no need to fit unknown exponents as previously proposed in critical power law behaviors. This generalized relation is verified by comparison with approaches to criticality for volcanic eruptions and creep failure. A new relation based on changes with stress is proposed as an alternative expression of Voight's relation, which is widely used to describe the accelerating precursory signals before material failure and broadly applied to volcanic eruptions, landslides and other phenomena. The new generalized relation reduces to Voight's relation if stress is limited to increase at a constant rate with time. This implies that the time-derivatives in Voight's analysis may be a subset of a more general expression connecting stress derivatives, and thus provides a potential method for forecasting these events.

  4. A landslide susceptibility prediction on a sample slope in Kathmandu Nepal associated with the 2015's Gorkha Earthquake

    NASA Astrophysics Data System (ADS)

    Kubota, Tetsuya; Prasad Paudel, Prem

    2016-04-01

    In 2013, some landslides induced by heavy rainfalls occurred in southern part of Kathmandu, Nepal which is located southern suburb of Kathmandu, the capital. These landslide slopes hit by the strong Gorkha Earthquake in April 2015 and seemed to destabilize again. Hereby, to clarify their susceptibility of landslide in the earthquake, one of these landslide slopes was analyzed its slope stability by CSSDP (Critical Slip Surface analysis by Dynamic Programming based on limit equilibrium method, especially Janbu method) against slope failure with various seismic acceleration observed around Kathmandu in the Gorkha Earthquake. The CSSDP can detect the landslide slip surface which has minimum Fs (factor of safety) automatically using dynamic programming theory. The geology in this area mainly consists of fragile schist and it is prone to landslide occurrence. Field survey was conducted to obtain topological data such as ground surface and slip surface cross section. Soil parameters obtained by geotechnical tests with field sampling were applied. Consequently, the slope has distinctive characteristics followings in terms of slope stability: (1) With heavy rainfall, it collapsed and had a factor of safety Fs <1.0 (0.654 or more). (2) With seismic acceleration of 0.15G (147gal) observed around Kathmandu, it has Fs=1.34. (3) With possible local seismic acceleration of 0.35G (343gal) estimated at Kathmandu, it has Fs=0.989. If it were very shallow landslide and covered with cedars, it could have Fs =1.055 due to root reinforcement effect to the soil strength. (4) Without seismic acceleration and with no rainfall condition, it has Fs=1.75. These results can explain the real landslide occurrence in this area with the maximum seismic acceleration estimated as 0.15G in the vicinity of Kathmandu by the Gorkha Earthquake. Therefore, these results indicate landslide susceptibility of the slopes in this area with strong earthquake. In this situation, it is possible to predict

  5. Landslides triggered by the 14 November 2016 Mw 7.8 Kaikōura Earthquake, New Zealand

    Massey, C.; Townsend, D.; Rathje, Ellen M.; Allstadt, Kate E.; Lukovic, B.; Kaneko, Yoshihiro; Bradley, Brendon A.; Wartman, J.; Jibson, Randall W.; Petley, D. N.; Horspool, Nick; Hamling, I.; Carey, J.; Cox, S.; Davidson, John; Dellow, S.; Godt, Jonathan W.; Holden, Christopher; Jones, Katherine D.; Kaiser, Anna E.; Little, M.; Lyndsell, B.; McColl, S.; Morgenstern, R.; Rengers, Francis K.; Rhoades, D.; Rosser, B.; Strong, D.; Singeisen, C.; Villeneuve, M.

    2018-01-01

    The 14 November 2016 Mw">MwMw 7.8 Kaikōura earthquake generated more than 10,000 landslides over a total area of about 10,000  km2">10,000  km210,000  km2, with the majority concentrated in a smaller area of about 3600  km2">3600  km23600  km2. The largest landslide triggered by the earthquake had an approximate volume of 20(±2)  M m3">20(±2)  M m320(±2)  M m3, with a runout distance of about 2.7 km, forming a dam on the Hapuku River. In this article, we present version 1.0 of the landslide inventory we have created for this event. We use the inventory presented in this article to identify and discuss some of the controls on the spatial distribution of landslides triggered by the Kaikōura earthquake. Our main findings are (1) the number of medium to large landslides (source area ≥10,000  m2">≥10,000  m2≥10,000  m2) triggered by the Kaikōura earthquake is smaller than for similar‐sized landslides triggered by similar magnitude earthquakes in New Zealand; (2) seven of the largest eight landslides (from 5 to 20  M m3">20  M m320  M m3) occurred on faults that ruptured to the surface during the earthquake; (3) the average landslide density within 200 m of a mapped surface fault rupture is three times that at a distance of 2500 m or more from a mapped surface fault rupture; (4) the “distance to fault” predictor variable, when used as a proxy for ground‐motion intensity, and when combined with slope angle, geology, and elevation variables, has more power in predicting landslide probability than the modeled peak ground acceleration or peak ground velocity; and (5) for the same slope angles, the coastal slopes have landslide point densities that are an order of magnitude greater than those in similar materials on the inland slopes, but their source areas are significantly smaller.

  6. Assessment of earthquake-triggered landslide susceptibility in El Salvador based on an Artificial Neural Network model

    NASA Astrophysics Data System (ADS)

    García-Rodríguez, M. J.; Malpica, J. A.

    2010-06-01

    This paper presents an approach for assessing earthquake-triggered landslide susceptibility using artificial neural networks (ANNs). The computational method used for the training process is a back-propagation learning algorithm. It is applied to El Salvador, one of the most seismically active regions in Central America, where the last severe destructive earthquakes occurred on 13 January 2001 (Mw 7.7) and 13 February 2001 (Mw 6.6). The first one triggered more than 600 landslides (including the most tragic, Las Colinas landslide) and killed at least 844 people. The ANN is designed and programmed to develop landslide susceptibility analysis techniques at a regional scale. This approach uses an inventory of landslides and different parameters of slope instability: slope gradient, elevation, aspect, mean annual precipitation, lithology, land use, and terrain roughness. The information obtained from ANN is then used by a Geographic Information System (GIS) to map the landslide susceptibility. In a previous work, a Logistic Regression (LR) was analysed with the same parameters considered in the ANN as independent variables and the occurrence or non-occurrence of landslides as dependent variables. As a result, the logistic approach determined the importance of terrain roughness and soil type as key factors within the model. The results of the landslide susceptibility analysis with ANN are checked using landslide location data. These results show a high concordance between the landslide inventory and the high susceptibility estimated zone. Finally, a comparative analysis of the ANN and LR models are made. The advantages and disadvantages of both approaches are discussed using Receiver Operating Characteristic (ROC) curves.

  7. Large-scale mapping of landslides in the epicentral area Loma Prieta earthquake of October 17, 1989, Santa Cruz County

    SciT

    Spittler, T.E.; Sydnor, R.H.; Manson, M.W.

    1990-01-01

    The Loma Prieta earthquake of October 17, 1989 triggered landslides throughout the Santa Cruz Mountains in central California. The California Department of Conservation, Division of Mines and Geology (DMG) responded to a request for assistance from the County of Santa Cruz, Office of Emergency Services to evaluate the geologic hazard from major reactivated large landslides. DMG prepared a set of geologic maps showing the landslide features that resulted from the October 17 earthquake. The principal purpose of large-scale mapping of these landslides is: (1) to provide county officials with regional landslide information that can be used for timely recovery ofmore » damaged areas; (2) to identify disturbed ground which is potentially vulnerable to landslide movement during winter rains; (3) to provide county planning officials with timely geologic information that will be used for effective land-use decisions; (4) to document regional landslide features that may not otherwise be available for individual site reconstruction permits and for future development.« less

  8. Identifying Alteration and Water on MT. Baker, WA with Geophysics: Implications for Volcanic Landslide Hazards

    NASA Astrophysics Data System (ADS)

    Finn, C.; Deszcz-Pan, M.; Bedrosian, P.; Minsley, B. J.

    2016-12-01

    Helicopter magnetic and electromagnetic (HEM) data, along with rock property measurements, local ground-based gravity, time domain electromagnetic (TEM) and nuclear magnetic resonance (NMR) data help identify alteration and water-saturated zones on Mount Baker, Washington. Hydrothermally altered rocks, particularly if water-saturated, can weaken volcanic edifices, increasing the potential for catastrophic sector collapses that can lead to far traveled and destructive debris flows. At Mount Baker volcano, collapses of hydrothermally altered rocks from the edifice have generated numerous debris flows that constitute their greatest volcanic hazards. Critical to quantifying this hazard is knowledge of the three-dimensional distribution of pervasively altered rock, shallow groundwater and ice that plays an important role in transforming debris avalanches to far traveled lahars. The helicopter geophysical data, combined with geological mapping and rock property measurements, indicate the presence of localized zones of less than 100 m thickness of water-saturated hydrothermally altered rock beneath Sherman Crater and the Dorr Fumarole Fields at Mt. Baker. New stochastic inversions of the HEM data indicate variations in resistivity in inferred perched aquifers—distinguishing between fresh and saline waters, possibly indicating the influence of nearby alteration and/or hydrothermal systems on water quality. The new stochastic results better resolve ice thickness than previous inversions, and also provide important estimates of uncertainty on ice thickness and other parameters. New gravity data will help constrain the thickness of the ice and alteration. Nuclear magnetic resonance data indicate that the hydrothermal clays contain 50% water with no evidence for water beneath the ice. The HEM data identify water-saturated fresh volcanic rocks from the surface to the detection limit ( 100 m) over the entire summit of Mt. Baker. Localized time domain EM soundings indicate that

  9. Earthquake and submarine landslide tsunamis: how can we tell the difference? (Invited)

    NASA Astrophysics Data System (ADS)

    Tappin, D. R.; Grilli, S. T.; Harris, J.; Geller, R. J.; Masterlark, T.; Kirby, J. T.; Ma, G.; Shi, F.

    2013-12-01

    Several major recent events have shown the tsunami hazard from submarine mass failures (SMF), i.e., submarine landslides. In 1992 a small earthquake triggered landslide generated a tsunami over 25 meters high on Flores Island. In 1998 another small, earthquake-triggered, sediment slump-generated tsunami up to 15 meters high devastated the local coast of Papua New Guinea killing 2,200 people. It was this event that led to the recognition of the importance of marine geophysical data in mapping the architecture of seabed sediment failures that could be then used in modeling and validating the tsunami generating mechanism. Seabed mapping of the 2004 Indian Ocean earthquake rupture zone demonstrated, however, that large, if not great, earthquakes do not necessarily cause major seabed failures, but that along some convergent margins frequent earthquakes result in smaller sediment failures that are not tsunamigenic. Older events, such as Messina, 1908, Makran, 1945, Alaska, 1946, and Java, 2006, all have the characteristics of SMF tsunamis, but for these a SMF source has not been proven. When the 2011 tsunami struck Japan, it was generally assumed that it was directly generated by the earthquake. The earthquake has some unusual characteristics, such as a shallow rupture that is somewhat slow, but is not a 'tsunami earthquake.' A number of simulations of the tsunami based on an earthquake source have been published, but in general the best results are obtained by adjusting fault rupture models with tsunami wave gauge or other data so, to the extent that they can model the recorded tsunami data, this demonstrates self-consistency rather than validation. Here we consider some of the existing source models of the 2011 Japan event and present new tsunami simulations based on a combination of an earthquake source and an SMF mapped from offshore data. We show that the multi-source tsunami agrees well with available tide gauge data and field observations and the wave data from

  10. A review of mechanisms and modelling procedures for landslide tsunamis

    NASA Astrophysics Data System (ADS)

    Løvholt, Finn; Harbitz, Carl B.; Glimsdal, Sylfest

    2017-04-01

    Landslides, including volcano flank collapses or volcanically induced flows, constitute the second-most important cause of tsunamis after earthquakes. Compared to earthquakes, landslides are more diverse with respect to how they generation tsunamis. Here, we give an overview over the main tsunami generation mechanisms for landslide tsunamis. In the presentation, a mix of results using analytical models, numerical models, laboratory experiments, and case studies are used to illustrate the diversity, but also to point out some common characteristics. Different numerical modelling techniques for the landslide evolution, and the tsunami generation and propagation, as well as the effect of frequency dispersion, are also briefly discussed. Basic tsunami generation mechanisms for different types of landslides, including large submarine translational landslide, to impulsive submarine slumps, and violent subaerial landslides and volcano flank collapses, are reviewed. The importance of the landslide kinematics is given attention, including the interplay between landslide acceleration, landslide velocity to depth ratio (Froude number) and dimensions. Using numerical simulations, we demonstrate how landslide deformation and retrogressive failure development influence tsunamigenesis. Generation mechanisms for subaerial landslides, are reviewed by means of scaling relations from laboratory experiments and numerical modelling. Finally, it is demonstrated how the different degree of complexity in the landslide tsunamigenesis needs to be reflected by increased sophistication in numerical models.

  11. Distribution and features of landslides induced by the 2008 Wengchuan Earthquake, Sichuan, China

    NASA Astrophysics Data System (ADS)

    Chigira, M.; Xiyong, W.; Inokuchi, T.; Gonghui, W.

    2009-04-01

    2008 Sichuan earthquake with a magnitude of Mw 7.9 induced numerous mass movements around the fault surface ruptures of which maximum separations we observed were 3.6 m vertical and 1.5 m horizontal (right lateral). The affected area was mountainous areas with elevations from 1000 m to 4500 m on the west of the Sichuan Basin. The NE-trending Longmenshan fault zone runs along the boundary between the mountains on the west and the Sichuan basin (He and Tsukuda, 2003), of which Yinghsiuwan-Beichuan fault was the main fault that generated the 2008 earthquake (Xu, 2008). The basement rocks of the mountainous areas range from Precambrian to Cretaceous in age. They are basaltic rocks, granite, phyllite, dolostone, limestone, alternating beds of sandstone and shale, etc. There were several types of landslides ranging from small, shallow rockslide, rockfall, debris slide, deep rockslide, and debris flows. Shallow rockslide, rock fall, and debris slide were most common and occurred on convex slopes or ridge tops. When we approached the epicentral area, first appearing landslides were of this type and the most conspicuous was a failure of isolated ridge-tops, where earthquake shaking would be amplified. As for rock types, slopes of granitic rocks, hornfels, and carbonate rocks failed in wide areas to the most. They are generally hard and their fragments apparently collided and repelled to each other and detached from the slopes. Alternating beds of sandstone and mudstone failed on many slopes near the fault ruptures, including Yinghsiuwan near the epicenter. Many rockfalls occurred on cliffs, which had taluses on their feet. The fallen rocks tumbled down and mostly stopped within the talus surfaces, which is quite reasonable because taluses generally develop by this kind of processes. Many rockslides occurred on slopes of carbonate rocks, in which dolostone or dolomitic limestone prevails. Deep-seated rockslide occurred on outfacing slopes and shallow rockslide and rockfall

  12. Landslide!

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-486, 17 September 2003

    This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part of a deposit created by a landslide off the wall of a crater near 12.3oN, 21.3oW. The crater wall is not shown; it is several kilometers to the left of this picture. The debris that slid from the crater wall came from the left/upper left (northwest) and moved toward the lower right (southeast). The crater floor onto which the debris was deposited has more small meteor craters on it than does the landslide material; this indicates that there was a considerable interval between the time when the crater floor formed, and when the landslide occurred. This picture covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  13. Instrumental shaking thresholds for seismically induced landslides and preliminary report on landslides triggered by the October 17, 1989, Loma Prieta, California earthquake

    Harp, E.L.

    1993-01-01

    The generation of seismically induced landslide depends on the characteristics of shaking as well as mechanical properties of geologic materials. A very important parameter in the study of seismically induced landslide is the intensity based on a strong-motion accelerogram: it is defined as Arias intensity and is proportional to the duration of the shaking record as well as the amplitude. Having a theoretical relationship between Arias intensity, magnitude and distance it is possible to predict how far away from the seismic source landslides are likely to occur for a given magnitude earthquake. Field investigations have established that the threshold level of Arias intensity depends also on site effects, particularly the fracture characteristics of the outcrops present. -from Author

  14. Possible multihazard events (tsunamis, earthquakes, landslides) expected on the North Bulgarian Black sea coast

    NASA Astrophysics Data System (ADS)

    Ranguelov, B.; Gospodinopv, D.

    2009-04-01

    Earthquakes The area is famous with its seismic regime. The region usually shows non regular behavior of the strong events occurrence. There are episodes of activation and between them long periods of seismic quiescence. The most important one is at the I-st century BC when according to the chronicler Strabo, the ancient Greek colony "Bisone sank in the waters of the sea". The seismic source is known as Shabla-Kaliakra zone with the best documented seismic event of 31st March 1901. This event had a magnitude of 7.2 (estimated by the macroseismic transformation formula) with a source depth of about 10-20 km. The epicenter was located in the aquatory of the sea. The observed macroseismic intensity on the land reached the maximum value of X degree MSK. This event produced a number of secondary effects - landslides, rockfalls, subsidence, extensive destruction of the houses located around and tsunami (up to 3 meters height observed at Balchik port. This event is selected as referent one. Tsunamis Such earthquakes (magnitude greater then 7.0) almost always trigger tsunamis. They could be generated by the earthquake rupture process, or more frequently by the secondary triggered phenomena - landslides (submarine or surface) and/or other geodynamic phenomena - rock falls, degradation of gas hydrates, etc. the most famous water level change is described by Strabo - related to the great catastrophe. The area shows also some other expressions about tsunamis - the last one - a non seismic tsunami at 7th May, 2007 with maximum observed amplitudes of about 3 meters water level changes. Landslides The area on the north Bulgarian Black Sea coast is covered by many active landslides. They have different size, depth and activation time. Most of them are located near the coast line thus presenting huge danger about the beaches, tourist infrastructure, population and historical heritage. The most famous landslide (subsidence) is related with the I-st century BC seismic event, when a

  15. Modelling low-frequency volcanic earthquakes in a viscoelastic medium with topography

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Neuberg, Jürgen; Jolly, Arthur

    2004-11-01

    Magma properties are fundamental to explain the volcanic eruption style as well as the generation and propagation of seismic waves. This study focusses on magma properties and rheology and their impact on low-frequency volcanic earthquakes. We investigate the effects of anelasticity and topography on the amplitudes and spectra of synthetic low-frequency earthquakes. Using a 2-D finite-difference scheme, we model the propagation of seismic energy initiated in a fluid-filled conduit embedded in a homogeneous viscoelastic medium with topography. We model intrinsic attenuation by linear viscoelastic theory and we show that volcanic media can be approximated by a standard linear solid (SLS) for seismic frequencies above 2 Hz. Results demonstrate that attenuation modifies both amplitudes and dispersive characteristics of low-frequency earthquakes. Low frequency volcanic earthquakes are dispersive by nature; however, if attenuation is introduced, their dispersion characteristics will be altered. The topography modifies the amplitudes, depending on the position of the seismographs at the surface. This study shows that we need to take into account attenuation and topography to interpret correctly observed low-frequency volcanic earthquakes. It also suggests that the rheological properties of magmas may be constrained by the analysis of low-frequency seismograms.

  16. Landslides and liquefaction triggered by the M 7.9 denali fault earthquake of 3 November 2002

    Harp, E.L.; Jibson, R.W.; Kayen, R.E.; Keefer, D.K.; Sherrod, B.L.; Carver, G.A.; Collins, B.D.; Moss, R.E.S.; Sitar, N.

    2003-01-01

    The moment magnitude (M) 7.9 Denali Fault earthquake in Alaska of 3 November 2002 triggered an unusual pattern of landslides and liquefaction effects. The landslides were primarily rock falls and rock slides that ranged in volume from a few cubic meters to the 40 million-cubic-meter rock avalanche that covered much of the McGinnis Glacier. Landslides were concentrated in a narrow zone ???30 km wide that straddled the fault rupture zone over its entire 300 km length. Large rock avalanches all clustered at the western end of the rupture zone where acceleration levels are reported to have been the highest. Liquefaction effects, consisting of sand blows, lateral spreads, and settlement, were widespread within susceptible alluvial deposits extending from Fairbanks eastward several hundred kilometers. The liquefaction effects displayed a pattern of increasing concentration and severity from west to east and extended well beyond the zone of landslides, which is unusual. The contrasting patterns formed by the distributions of landslides and liquefaction effects initially seemed to be inconsistent; however, preliminary analyses of strong-motion records from the earthquake offer a possible explanation for the unusual ground-failure patterns that are related to three subevents that have been discerned from the earthquake records.

  17. Evidence for earthquake triggering of large landslides in coastal Oregon, USA

    Schulz, W.H.; Galloway, S.L.; Higgins, J.D.

    2012-01-01

    Landslides are ubiquitous along the Oregon coast. Many are large, deep slides in sedimentary rock and are dormant or active only during the rainy season. Morphology, observed movement rates, and total movement suggest that many are at least several hundreds of years old. The offshore Cascadia subduction zone produces great earthquakes every 300–500 years that generate tsunami that inundate the coast within minutes. Many slides and slide-prone areas underlie tsunami evacuation and emergency response routes. We evaluated the likelihood of existing and future large rockslides being triggered by pore-water pressure increase or earthquake-induced ground motion using field observations and modeling of three typical slides. Monitoring for 2–9 years indicated that the rockslides reactivate when pore pressures exceed readily identifiable levels. Measurements of total movement and observed movement rates suggest that two of the rockslides are 296–336 years old (the third could not be dated). The most recent great Cascadia earthquake was M 9.0 and occurred during January 1700, while regional climatological conditions have been stable for at least the past 600 years. Hence, the estimated ages of the slides support earthquake ground motion as their triggering mechanism. Limit-equilibrium slope-stability modeling suggests that increased pore-water pressures could not trigger formation of the observed slides, even when accompanied by progressive strength loss. Modeling suggests that ground accelerations comparable to those recorded at geologically similar sites during the M 9.0, 11 March 2011 Japan Trench subduction-zone earthquake would trigger formation of the rockslides. Displacement modeling following the Newmark approach suggests that the rockslides would move only centimeters upon coseismic formation; however, coseismic reactivation of existing rockslides would involve meters of displacement. Our findings provide better understanding of the dynamic coastal bluff

  18. Co-seismic landslide topographic analysis based on multi-temporal DEM-A case study of the Wenchuan earthquake.

    PubMed

    Ren, Zhikun; Zhang, Zhuqi; Dai, Fuchu; Yin, Jinhui; Zhang, Huiping

    2013-01-01

    Hillslope instability has been thought to be one of the most important factors for landslide susceptibility. In this study, we apply geomorphic analysis using multi-temporal DEM data and shake intensity analysis to evaluate the topographic characteristics of the landslide areas. There are many geomorphologic analysis methods such as roughness, slope aspect, which are also as useful as slope analysis. The analyses indicate that most of the co-seismic landslides occurred in regions with roughness, hillslope and slope aspect of >1.2, >30, and between 90 and 270, respectively. However, the intersection regions from the above three methods are more accurate than that derived by applying single topographic analysis method. The ground motion data indicates that the co-seismic landslides mainly occurred on the hanging wall side of Longmen Shan Thrust Belt within the up-down and horizontal peak ground acceleration (PGA) contour of 150 PGA and 200 gal, respectively. The comparisons of pre- and post-earthquake DEM data indicate that the medium roughness and slope increased, the roughest and steepest regions decreased after the Wenchuan earthquake. However, slope aspects did not even change. Our results indicate that co-seismic landslides mainly occurred at specific regions of high roughness, southward and steep sloping areas under strong ground motion. Co-seismic landslides significantly modified the local topography, especially the hillslope and roughness. The roughest relief and steepest slope are significantly smoothed; however, the medium relief and slope become rougher and steeper, respectively.

  19. Landslide!

    2017-05-12

    This image from NASA Mars Reconnaissance Orbiter shows a fresh well-preserved landslide scarp and rocky deposit off the edge of a streamlined mesa in Simud Valles, a giant outflow channel carved by ancient floods. A stereo anaglyph is available at https://photojournal.jpl.nasa.gov/catalog/PIA21633

  20. Landslide

    2014-08-26

    This image from NASA 2001 Mars Odyssey spacecraft shows a landslide deposit within a complex crater note the ejecta to the top and bottom of the image. There is a smaller complex crater on the ejecta to the north of the larger crater.

  1. Rock falls landslides in Abruzzo (Central Italy) after recent earthquakes: morphostructural control

    NASA Astrophysics Data System (ADS)

    Piacentini, T.; Miccadei, E.; Di Michele, R.; Esposito, G.

    2012-04-01

    Recent earthquakes show that damages due to collateral effects could, in some cases exceed the economic and social losses directly connected to the seismic shaking. The earthquake heavily damaged urban areas and villages and induced several coseismic deformations and geomorphologic effects, including different types of instability such as: rock falls, debris falls, sink holes, ground collapses, liquefaction, etc. Among the effects induced by the seismic energy release, landslides are one of the most significant in terms of hazard and related risk, owing to the occurrence of exposed elements. This work analyzes the geomorphological effects, and particularly the rock falls, which occurred in the L'Aquila area during and immediately after the April 2009 earthquake. The analysis is focused mainly on the rock fall distribution related to the local morphostructural setting. Rock falls occurred mostly on calcareous bedrock slopes or on scarps developed on conglomerates and breccias of Quaternary continental deposits. Geological and geomorphological surveys have outlined different types of rock falls on different morpho-structural settings, which can be summarized as follow: 1)rock falls on calcareous faulted homoclinal ridges; 2)rock falls on calcareous rock slopes of karst landforms; 3)rock falls on structural scarps on conglomerates and breccias of Quaternary continental deposits. The first type of rockfall occurred particularly along main gorges carved on calcareous rocks and characterised by very steep fault slopes and structural slopes (i.e. San Venanzio Gorges, along the Aterno river). In these cases already unstable slopes due to lithological and structural control were triggered as rockfalls also at high distance from the epicentre area. These elements provide useful indications both at local scale, for seismic microzonation studies and seismic risk prevention, and at regional scale, for updating studies and inventory of landslides.

  2. Preliminary results on landslides triggered by the Mw 7.8 Kaikoura earthquake of 14 November 2016 in northeast South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Gorum, Tolga; Yildirim, Cengiz

    2017-04-01

    This study presents the first results on analysis of the landslides triggered by the Mw 7.8 Kaikoura earthquake that occurred on November 14, 2016 in the region between the Hikurangi subduction system of the North Island and the oblique collisional regime of the South Island (Alpine Fault). The earthquake ruptured several faults that expand into two different tectonic domains which are compose of the strike-slip Marlborough fault system and the compressional North Canterbury Fault Zone. Here we present the preliminary mapping results of the distribution of landslides triggered by the earthquake. An extensive landslide interpretation was carried out using sets of optical high resolution satellite images (e.g. Sentinel-2 and Göktürk-2) for both the pre- and post-earthquake situation. The landslides were identified and mapped as polygons using multi-temporal visual image interpretation based on satellite imagery and morphological elements of landslide diagnostic indicators. Nearly 8,500 individual landslides with different sizes and types were mapped. The distribution pattern of the mapped coseismic landslides shows that the slope failures are highly concentrated along the ruptured faults and side slopes of the structurally controlled major rivers such as Hapuku and Clarence Rivers that drain the northeastern slopes of the region. Our spatial analysis of landslide occurrences with ground acceleration, lithology, slope, topographic relief and surface deformation indicated extensive control of steep slope and high topographic relief on landslides with ground acceleration as the trigger. We show that spatial distribution of slope failures shows decreasing frequency away from the earthquake faults up to 25 km towards east, and abundance of landslides spatially coincides with the coseismic fault geometries and aftershock distributions. We conclude that combined effect of complex rupture dynamics and topography primarily control the distribution pattern of the landslides

  3. Exploring Interactions Between Subduction Zone Earthquakes and Volcanic Activity in the South Central Alaskan Subduction Zone

    NASA Astrophysics Data System (ADS)

    Lanagan, K. M.; Richardson, E.

    2012-12-01

    Although great earthquakes such as the recent moment-magnitude (M) 9 Tohoku-Oki earthquake have been shown to trigger remote seismicity in volcanoes, the extent to which subduction zone earthquakes can trigger shallow seismic swarms at volcanoes is largely unexplored. Unknowns in this relationship include the upper limit of distance, the lower limit of magnitude, the upper time limit between events, and the effects of rupture directivity. We searched the Advanced National Seismic System earthquake catalog from 1989 - 2011 for correlations in space and time between M > 5.0 earthquakes in the south central Alaskan subduction zone (between 58.5°N and 62.5°N, and 150.7°W and 154.7°W) and volcanic activity at Mt. Redoubt, Mt. Iliamna, and Mt. Spurr volcanoes. There are 48 earthquakes M > 5 in this catalog; five of these are M > 6. The depths of the 48 M>5 events range from 49km to 220km, and they are all between 100km and 350km of the three volcanoes. Preliminary analysis of our catalog shows that four of the five M > 6 earthquakes are followed by a volcanic earthquake swarm at either Redoubt or Spurr within 100 days, and three of them are followed by a volcanic earthquake swarm within a month. None of these events correlated in space and time with swarms at Mt. Iliamna. We are also searching for swarms and moderate earthquakes occurring in time windows far removed from each other. The likeliest case of remotely triggered seismicity in our search area to date occurred on January 24 2009, when a magnitude 5.8 earthquake beneath the Kenai Peninsula at 59.4°N, 152.8°W, and 95km depth was immediately followed by an increase of volcanic activity at Mt. Redoubt approximately 153km away. The first swarm began on Jan 25 2009. On Jan 30 2009, volcanologists at the Alaskan Volcano observatory determined the increased volcanic seismicity was indicative of an impending eruption. Mt. Redoubt erupted on March 15 2009. Proposed mechanisms for triggering of volcanoes by

  4. Space geodetic tools provide early warnings for earthquakes and volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Aoki, Yosuke

    2017-04-01

    Development of space geodetic techniques such as Global Navigation Satellite System and Synthetic Aperture Radar in last few decades allows us to monitor deformation of Earth's surface in unprecedented spatial and temporal resolution. These observations, combined with fast data transmission and quick data processing, enable us to quickly detect and locate earthquakes and volcanic eruptions and assess potential hazards such as strong earthquake shaking, tsunamis, and volcanic eruptions. These techniques thus are key parts of early warning systems, help identify some hazards before a cataclysmic event, and improve the response to the consequent damage.

  5. Coupling of Sentinel-1, Sentinel-2 and ALOS-2 to assess coseismic deformation and earthquake-induced landslides following 26 June, 2016 earthquake in Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Vajedian, Sanaz; Motagh, Mahdi; Wetzel, Hans-Ulrich; Teshebaeva, Kanayim

    2017-04-01

    The active deformation in Kyrgyzstan results from the collision between Indian and Asia tectonic plates at a rate of 29 ± 1 mm/yr. This collision is accommodated by deformation on prominent faults, which can be ruptured coseismically and trigger other hazards like landslides. Many earthquake and earthquake-induced landslides in Kyrgyzstan occur in mountainous areas, where limited accessibility makes ground-based measurements for the assessment of their impact a challenging task. In this context, remote sensing measurements are extraordinary useful as they improve our knowledge about coseismic rupture process and provide information on other types of hazards that are triggered during and/or after the earthquakes. This investigation aims to use L-band ALOS/PALSAR, C-band Sentinel-1, Sentinel-2 data to evaluate fault slip model and coseismic-induced landslides related to 26 June 2016 Sary-Tash earthquake, southwest Kyrgyzstan. First we implement three methods to measure coseismic surface motion using radar data including Interferometric SAR (InSAR) analysis, SAR tracking technique and multiple aperture InSAR (MAI), followed by using Genetic Algorithm (GA) to invert the final displacement field to infer combination of orientation, location and slip on rectangular uniform slip fault plane. Slip distribution analysis is done by applying Tikhonov regularization to solve the constrained least-square method with Laplacian smoothing approach. The estimated coseismic slip model suggests a nearly W-E thrusting fault ruptured during the earthquake event in which the main rupture occurred at a depth between 11 and 14 km. Second, the local phase shifts related to landslides are inferred by detailed analysis pre-seismic, coseismic and postseismic C-band and L-band interferograms and the results are compared with the interpretations derived from Sentinel-2 data acquired before and after the earthquake.

  6. Analysis of the effects of geological and geomorphological factors on earthquake triggered landslides using artificial neural networks (ANN)

    NASA Astrophysics Data System (ADS)

    Kawabata, D.; Bandibas, J.

    2007-12-01

    The occurrence of landslide is the result of the interaction of complex and diverse environmental factors. The geomorphic and geologic features, rock types and vegetative cover are important base factors of landslide occurrence. However, determining the relationship between these factors and landslide occurrence is very difficult using conventional mathematical analysis. The use of an advanced computing technique for this kind of analysis is very important. Artificial neural network (ANN) has recently been included in the list of analytical tools for a wide range of applications in the natural sciences research fields. One of the advantages of using ANN for pattern recognition is that it can handle data at any measurement scale ranging from nominal, ordinal to linear and ratio, and any form of data distribution (Wang et al., 1995). In addition, it can easily handle qualitative variables making it widely used in integrated analysis of spatial data from multiple sources for predicting and classification. This study focuses on the definition of the relationship between geological factors and landslide occurrence using artificial neural networks. The study also focuses on the effect of the DTMs (e.g. ASTER DTM, ALSM, digitized from paper map and digital photogrammetric measurement data). The main aim of the study is to generate landslide susceptibility index map using the defined relationship using ANN. Landslide data in the Chuetsu region were used in this research. The 2004 earthquake triggered many landslides in the region. The initial results of the study showed that ANN is more accurate in defining the relationship between geological and geomorphological factors and landslide occurrence. It also determined the best combination of geological and geomorphological factors that is directly related to landslide occurrence.

  7. Landslides triggered by the 2002 Denali fault, Alaska, earthquake and the inferred nature of the strong shaking

    Jibson, R.W.; Harp, E.L.; Schulz, W.; Keefer, D.K.

    2004-01-01

    The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15 ?? 106 m3. The pattern of landsliding was unusual; the number of slides was less than expected for an earthquake of this magnitude, and the landslides were concentrated in a narrow zone 30-km wide that straddled the fault rupture over its entire 300-km length. The large rock avalanches all clustered along the western third of the rupture zone where acceleration levels and ground-shaking frequencies are thought to have been the highest. Inferences about near-field strong shaking characteristics drawn from the interpretation of the landslide distribution are consistent with results of recent inversion modeling that indicate high-frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east. ?? 2004, Earthquake Engineering Research Institute.

  8. Landslides, forest fires, and earthquakes: examples of self-organized critical behavior

    NASA Astrophysics Data System (ADS)

    Turcotte, Donald L.; Malamud, Bruce D.

    2004-09-01

    Per Bak conceived self-organized criticality as an explanation for the behavior of the sandpile model. Subsequently, many cellular automata models were found to exhibit similar behavior. Two examples are the forest-fire and slider-block models. Each of these models can be associated with a serious natural hazard: the sandpile model with landslides, the forest-fire model with actual forest fires, and the slider-block model with earthquakes. We examine the noncumulative frequency-area statistics for each natural hazard, and show that each has a robust power-law (fractal) distribution. We propose an inverse-cascade model as a general explanation for the power-law frequency-area statistics of the three cellular-automata models and their ‘associated’ natural hazards.

  9. Structures of Xishan village landslide in Li County, Sichuan, China, inferred from high-frequency receiver functions of local earthquakes

    NASA Astrophysics Data System (ADS)

    Wei, Z.; Chu, R.

    2017-12-01

    Teleseismic receiver function methods are widely used to study the deep structural information beneath the seismic station. However, teleseismic waveforms are difficult to extract the high-frequency receiver function, which are insufficient to constrain the shallow structure because of the inelastic attenuation effect of the earth. In this study, using the local earthquake waveforms collected from 3 broadband stations deployed on the Xishan village landslide in Li County in Sichuan Province, we used the high-frequency receiver function method to study the shallow structure beneath the landslide. We developed the Vp-k (Vp/Vs) staking method of receiver functions, and combined with the H-k stacking and waveform inversion methods of receiver functions to invert the landslide's thickness, S-wave velocity and average Vp/Vs ratio beneath these stations, and compared the thickness with the borehole results. Our results show small-scale lateral variety of velocity structure, a 78-143m/s lower S-wave velocity in the bottom layer and 2.4-3.1 Vp/Vs ratio in the landslide. The observed high Vp/Vs ratio and low S-wave velocity in the bottom layer of the landslide are consistent with low electrical resistivity and water-rich in the bottom layer, suggesting a weak shear strength and potential danger zone in landslide h1. Our study suggest that the local earthquake receiver function can obtain the shallow velocity structural information and supply some seismic constrains for the landslide catastrophe mitigation.

  10. The January 2006 Volcanic-Tectonic Earthquake Swarm at Mount Martin, Alaska

    Dixon, James P.; Power, John A.

    2009-01-01

    On January 8, 2006, a swarm of volcanic-tectonic earthquakes began beneath Mount Martin at the southern end of the Katmai volcanic cluster. This was the first recorded swarm at Mount Martin since continuous seismic monitoring began in 1996. The number of located earthquakes increased during the next four days, reaching a peak on January 11. For the next two days, the seismic activity decreased, and on January 14, the number of events increased to twice the previous day's total. Following this increase in activity, seismicity declined, returning to background levels by the end of the month. The Alaska Volcano Observatory located 860 earthquakes near Mount Martin during January 2006. No additional signs of volcanic unrest were noted in association with this earthquake swarm. The earthquakes in the Mount Martin swarm, relocated using the double difference technique, formed an elongated cluster dipping to the southwest. Focal mechanisms beneath Mount Martin show a mix of normal, thrust, and strike-slip solutions, with normal focal mechanisms dominating. For earthquakes more than 1 km from Mount Martin, all focal mechanisms showed normal faulting. The calculated b-value for the Mount Martin swarm is 0.98 and showed no significant change before, during, or after the swarm. The triggering mechanism for the Mount Martin swarm is unknown. The time-history of earthquake occurrence is indicative of a volcanic cause; however, there were no low-frequency events or observations, such as increased steaming associated with the swarm. During the swarm, there was no change in the b-value, and the distribution and type of focal mechanisms were similar to those in the period before the anomalous activity. The short duration of the swarm, the similarity in observed focal mechanisms, and the lack of additional signs of unrest suggest this swarm did not result from a large influx of magma within the shallow crust beneath Mount Martin.

  11. Engineering-geological model of the landslide of Güevejar (S Spain) reactivated by historical earthquakes

    NASA Astrophysics Data System (ADS)

    Delgado, José; García-Tortosa, Francisco J.; Garrido, Jesús; Giner, José; Lenti, Luca; López-Casado, Carlos; Martino, Salvatore; Peláez, José A.; Sanz de Galdeano, Carlos; Soler, Juan L.

    2015-04-01

    Landslides are a common ground effect induced by earthquakes of moderate to large magnitude. Most of them correspond to first-time instabilities induced by the seismic event, being the reactivation of pre-existing landslides less frequent in practice. The landslide of Güevejar (Granada province, S Spain) represents a case study of landslide that was reactivated, at least, two times by far field earthquakes: the Mw 8.7, 1755, Lisbon earthquake (with estimated epicentral distance of 680 km), and the Mw 6.5, 1884, Andalucia event (estimated epicentral distance of 45 km), but not by near field events of moderate magnitude (Mw < 6.0 and epicentral distances lower than 25 km). To study the seismic response of this landslide, a study has been conducted to elaborate an engineering-geological model. For this purpose, field work done included the elaboration of a detailed geological map (1:1000) of the landslide and surrounding areas, drilling of deep boreholes (80 m deep), down-hole measurement of both P and S wave velocities in the boreholes drilled, piezometric control of water table, MASW and ReMi profiles for determining the underlying structure of the sites tested (soil profile stratigraphy and the corresponding S-wave velocity of each soil level) and undisturbed sampling of the materials affected by the landslide. These samples were then tested in laboratory according to standard procedures for determination of both static (among which soil density, soil classification and shear strength) and dynamic properties (degradation curves for shear modulus and damping ratio with shear strain) of the landslide-involved materials. The model proposed corresponds to a complex landslide that combines a rototranslational mechanism with an earth-flow at its toe, which is characterized by a deep (> 50 m) sliding surface. The engineering-geological model constitutes the first step in an ongoing research devoted to understand how it could be reactivated during far field events. The

  12. A large landslide in volcanic rock: failure processes, geometry and propagation

    NASA Astrophysics Data System (ADS)

    Putu Krishna Wijaya, I.; Zangerl, Christian; Straka, Wolfgang; Mergili, Martin; Prasad Pudasaini, Shiva; Arifianti, Yukni

    2017-04-01

    The Jemblung landslide in Banjarnegara, Indonesia was one of the most destructive landslides in the country since 2006. This landslide caused at least 90 deaths while more than 1300 people were evacuated to safer areas. Concerning the failure mechanisms and type of material, the event can be characterized as a complex landslide (earth slide to earth flow). It originated in volcaniclastic soil/rock, i.e. andesites and lapilli-tuffs of varying degrees of weathering that lie above tuffaceous sandstones, conglomerates, as well as an alternation of shale and brown coal layers. Unmanned aerial vehicle (UAV) data from a secondary database are processed by using photogrammetric software to obtain an overview of the landslide geometry before and after the failure event. Stratigraphic field data and geoelectrical measurements are compared and correlated to build a geological-geometrical model and to estimate the volume of the landslide. Petrographical and XRD analysis are conducted to explain the mineral composition of parent rock and its weathering products. Rainfall as well as seismologic data are collected to study potential trigger and failure mechanisms. The geological-geometrical model of the landslide, digital terrain models of the process area and geotechnical soil properties are combined to model the initial sliding process by applying limit-equilibrium software products. Furthermore, the landslide propagation is simulated with the novel, GIS-based, two-phase mass flow modelling tool r.avaflow in order to improve the understanding of the dynamics of the Jemblung landslide.

  13. Identifying Water on Mt. Baker and Mt. St. Helens, WA with Geophysics: Implications for Volcanic Landslide Hazards

    NASA Astrophysics Data System (ADS)

    Finn, C.; Bedrosian, P.; Wisniewski, M.; Deszcz-Pan, M.

    2015-12-01

    Groundwater position, abundance, and flow rates within a volcano affect the transmission of fluid pressure, transport of mass and heat and formation of mechanically weak hydrothermal alteration influencing the stability of volcanoes. In addition, eruptions can shatter volcanic rocks, weakening the edifice. Helicopter magnetic and electromagnetic (HEM) data collected over Mt. Baker and Mt. St. Helens volcanoes reveal the distribution of water, shattered volcanic rocks and hydrothermal alteration essential to evaluating volcanic landslide hazards. These data, combined with geological mapping and rock property measurements, indicate the presence of localized <100 m thick zones of water-saturated hydrothermally altered rock beneath Sherman Crater and the Dorr Fumarole Fields at Mt. Baker. Nuclear magnetic resonance data indicate that the hydrothermal clays contain ~50% bound water with no evidence for free water ponded beneath the ice. The HEM data suggest water-saturated fresh volcanic rocks from the surface to the detection limit (~100 m) over the entire summit of Mt. Baker (below the ice). A 50-100 m thick high resistivity layer (>1500 ohm-m) corresponding to domes, debris avalanche, volcanic rocks and glaciers mantles the crater at Mt. St. Helens. Shallow low resistivity layers corresponding to fresh, cold water and hot brines are observed below the high resistivity surface in EM data. Shallow ground water mainly concentrates in shattered dome material in the crater of Mt. St. Helens. Aeromagnetic data indicate the location of basalts sandwiched between debris avalanche deposits and shattered dome material. The combination of the EM and magnetic data help map the location of the shattered dome material that is considered to be the failure surface for the 1980 debris avalanche. The EM data image the regional groundwater table near the base of the volcano. The geophysical identification of groundwater and weak layers constrain landslide hazards assessments.

  14. Glacier quakes mimicking volcanic earthquakes: The challenge of monitoring ice-clad volcanoes and some solutions

    NASA Astrophysics Data System (ADS)

    Allstadt, K.; Carmichael, J. D.; Malone, S. D.; Bodin, P.; Vidale, J. E.; Moran, S. C.

    2012-12-01

    Swarms of repeating earthquakes at volcanoes are often a sign of volcanic unrest. However, glaciers also can generate repeating seismic signals, so detecting unrest at glacier-covered volcanoes can be a challenge. We have found that multi-day swarms of shallow, low-frequency, repeating earthquakes occur regularly at Mount Rainier, a heavily glaciated stratovolcano in Washington, but that most swarms had escaped recognition until recently. Typically such earthquakes were too small to be routinely detected by the seismic network and were often buried in the noise on visual records, making the few swarms that had been detected seem more unusual and significant at the time they were identified. Our comprehensive search for repeating earthquakes through the past 10 years of continuous seismic data uncovered more than 30 distinct swarms of low-frequency earthquakes at Rainier, each consisting of hundreds to thousands of events. We found that these swarms locate high on the glacier-covered edifice, occur almost exclusively between late fall and early spring, and that their onset coincides with heavy snowfalls. We interpret the correlation with snowfall to indicate a seismically observable glacial response to snow loading. Efforts are underway to confirm this by monitoring glacier motion before and after a major snowfall event using ground based radar interferometry. Clearly, if the earthquakes in these swarms reflect a glacial source, then they are not directly related to volcanic activity. However, from an operational perspective they make volcano monitoring difficult because they closely resemble earthquakes that often precede and accompany volcanic eruptions. Because we now have a better sense of the background level of such swarms and know that their occurrence is seasonal and correlated with snowfall, it will now be easier to recognize if future swarms at Rainier are unusual and possibly related to volcanic activity. To methodically monitor for such unusual activity

  15. Landslide

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02160 Landslide

    This large landslide is located within Ganges Chasma.

    Image information: VIS instrument. Latitude -7.6N, Longitude 315.8E. 17 meter/pixel resolution.

    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.

    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.

  16. Landslide

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03582 Landslide

    This landslide occurred in Coprates Chasma.

    Image information: VIS instrument. Latitude 12.6S, Longitude 296.9E. 17 meter/pixel resolution.

    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.

    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.

  17. Modelling low-frequency volcanic earthquakes in a viscoelastic medium with topography

    NASA Astrophysics Data System (ADS)

    Jousset, P.; Neuberg, J.

    2003-04-01

    Magma properties are fundamental to explain the volcanic eruption style as well as the generation and propagation of seismic waves. This study focusses on rheological magma properties and their impact on low-frequency volcanic earthquakes. We investigate the effects of anelasticity and topography on the amplitudes and spectra of synthetic low-frequency earthquakes. Using a 2D finite difference scheme, we model the propagation of seismic energy initiated in a fluid-filled conduit embedded in a 2D homogeneous viscoelastic medium with topography. Topography is introduced by using a mapping procedure that stretches the computational rectangular grid into a grid which follows the topography. We model intrinsic attenuation by linear viscoelastic theory and we show that volcanic media can be approximated by a standard linear solid for seismic frequencies (i.e., above 2 Hz). Results demonstrate that attenuation modifies both amplitude and dispersive characteristics of low-frequency earthquakes. Low-frequency events are dispersive by nature; however, if attenuation is introduced, their dispersion characteristics will be altered. The topography modifies the amplitudes, depending on the position of seismographs at the surface. This study shows that we need to take into account attenuation and topography to interpret correctly observed low-frequency volcanic earthquakes. It also suggests that the rheological properties of magmas may be constrained by the analysis of low-frequency seismograms.

  18. Numerical simulation of the submarine landslides and tsunami occurred at Port Valdez, AK during 1964 Alaska Earthquake with Landslide-HySEA model

    NASA Astrophysics Data System (ADS)

    González-Vida, Jose M.; Ortega, Sergio; Macías, Jorge; Castro, Manuel J.; Escalante, Cipriano

    2017-04-01

    This is a benchmark problem recently proposed in the framework of the Landslide Tsunami Model Benchmarking Workshop organized by the NTHMP (National tsunami Hazard mitigation program -USA-) at Galveston (USA). The benchmark is based on the historical event which occurred at Port Valdez, AK during the Alaska Earthquake of March 27, 1964. The great disaster during the Mw9.2 Alaska Earthquake happened in the dock and harbour area of Port Valdez, where a massive submarine landslide generated a tsunami, inundating the waterfront up to two blocks inland. Then, a second wave crossed the waterfront 10-15 minutes after the first wave, carrying a large amount of the debris. It has been described as a violent surging wave only slightly smaller than the first. It is believed that the second wave which flooded the waterfront was originated at the other side of the Port Valdez near the Shoup Bay moraine. The benchmark consists in simulating with the (GPU based) Landslide-HySEA model the extent of inundation for two slide events, based on before and after bathymetry data, eye-witness observations of the event, and observed runup distribution. First, both landslides have been simulated separately, studying time series of the water waves at determined locations, runups at different areas and the extent of inundation around the first two blocks inland of Port Valdez. Then, the two landslides are triggered at the same time and the joint effect is studied. Obtained results are satisfactory and they agree with the existing observations. References Castro, M. J., Fernández-Nieto, E. D., González-Vida, J. M., Parés, C. (2011). Numerical Treatment of the Loss of Hyperbolicity of the Two-Layer Shallow-Water System. Journal of Scientific Computing, 48(1):16-40. Fernández, E.H., Bouchut, F., Bresh, D., Castro, M.J. and, Mangeney, A. (2008). A new Savage-Hutter type model for submarine avalanches and generated tsunami. J. Comp. Phys., 227: 7720-7754. Fernández-Nieto, E.D., Castro, M

  19. Evaluation of Tsunami Hazards in Kuwait from Possible Earthquake and Landslide Sources considering Effect of Natural Tide

    NASA Astrophysics Data System (ADS)

    Latcharote, P.

    2016-12-01

    Kuwait is one of the most important oil producers to the world and most of population and many vital facilities are located along the coasts. However, even with low or unknown tsunami risk, it is important to investigate tsunami hazards in this country to ensure safety of life and sustain the global economy. This study aimed to evaluate tsunami hazards along the coastal areas of Kuwait from both earthquake and landslide sources using numerical modeling. Tsunami generation and propagation was simulated using the two-layer model and the TUNAMI model. Four cases of earthquake scenarios are expected to generate tsunami along the Makran Subduction Zone (MSZ) based on historical events and worst cases possible to simulate tsunami propagation to the coastal areas of the Arabian Gulf. Case 1 (Mw 8.3) and Case 2 (Mw 8.3) are the replication of the 1945 Makran earthquake, whereas Case 3 (Mw 8.6) and Case 4 (Mw 9.0) are the worst-case scenarios. Tsunami numerical simulation was modelled with mesh size 30 arc-second using bathymetry and topography data from GEBCO. Preliminary results suggested that tsunamis generated by Case 1 and Case 2 will impose very small effects to Kuwait (< 0.1 m) while Case 3 and Case 4 can generate maximum tsunami amplitude up to 0.3 m to 1.0 m after 12 hours from the earthquake. In addition, this study considered tsunamis generated by landslide along the opposite Iranian coast of Kuwait bay. To preliminarily assess tsunami hazards, coastal landslides were assumed occurred at the volume of 1.0-2.0 km3 at three possible locations from their topographic features. The preliminary results revealed that tsunami generated by coastal landslides could impose a significant tsunami impact to Kuwait having maximum tsunami amplitude at the Falika Island in front of Kuwait bay and Azzour power and desalination plant about 0.5 m- 1.1 m depending on landslide volume and energy dissipation. Future works will include more accuracy of tsunami numerical simulation with

  20. Quantitative risk assessment of landslides triggered by earthquakes and rainfall based on direct costs of urban buildings

    NASA Astrophysics Data System (ADS)

    Vega, Johnny Alexander; Hidalgo, Cesar Augusto

    2016-11-01

    This paper outlines a framework for risk assessment of landslides triggered by earthquakes and rainfall in urban buildings in the city of Medellín - Colombia, applying a model that uses a geographic information system (GIS). We applied a computer model that includes topographic, geological, geotechnical and hydrological features of the study area to assess landslide hazards using the Newmark's pseudo-static method, together with a probabilistic approach based on the first order and second moment method (FOSM). The physical vulnerability assessment of buildings was conducted using structural fragility indexes, as well as the definition of damage level of buildings via decision trees and using Medellin's cadastral inventory data. The probability of occurrence of a landslide was calculated assuming that an earthquake produces horizontal ground acceleration (Ah) and considering the uncertainty of the geotechnical parameters and the soil saturation conditions of the ground. The probability of occurrence was multiplied by the structural fragility index values and by the replacement value of structures. The model implemented aims to quantify the risk caused by this kind of disaster in an area of the city of Medellín based on different values of Ah and an analysis of the damage costs of this disaster to buildings under different scenarios and structural conditions. Currently, 62% of ;Valle de Aburra; where the study area is located is under very low condition of landslide hazard and 38% is under low condition. If all buildings in the study area fulfilled the requirements of the Colombian building code, the costs of a landslide would be reduced 63% compared with the current condition. An earthquake with a return period of 475 years was used in this analysis according to the seismic microzonation study in 2002.

  1. Interpretation of earthquake-induced landslides triggered by the 12 May 2008, M7.9 Wenchuan earthquake in the Beichuan area, Sichuan Province, China using satellite imagery and Google Earth

    Sato, H.P.; Harp, E.L.

    2009-01-01

    The 12 May 2008 M7.9 Wenchuan earthquake in the People's Republic of China represented a unique opportunity for the international community to use commonly available GIS (Geographic Information System) tools, like Google Earth (GE), to rapidly evaluate and assess landslide hazards triggered by the destructive earthquake and its aftershocks. In order to map earthquake-triggered landslides, we provide details on the applicability and limitations of publicly available 3-day-post- and pre-earthquake imagery provided by GE from the FORMOSAT-2 (formerly ROCSAT-2; Republic of China Satellite 2). We interpreted landslides on the 8-m-resolution FORMOSAT-2 image by GE; as a result, 257 large landslides were mapped with the highest concentration along the Beichuan fault. An estimated density of 0.3 landslides/km2 represents a minimum bound on density given the resolution of available imagery; higher resolution data would have identified more landslides. This is a preliminary study, and further study is needed to understand the landslide characteristics in detail. Although it is best to obtain landslide locations and measurements from satellite imagery having high resolution, it was found that GE is an effective and rapid reconnaissance tool. ?? 2009 Springer-Verlag.

  2. Composite mechanism of the Büyükçekmece (Turkey) landslide as conditioning factor for earthquake-induced mobility

    NASA Astrophysics Data System (ADS)

    Martino, S.; Lenti, L.; Bourdeau, C.

    2018-05-01

    Earthquake-induced displacements of landslides are significantly conditioned by their 1D and 2D interactions with seismic waves, as currently proven by several studies. Nevertheless, the role of a more complex geological setting, responsible for a heterogeneous composition of the landslide mass, can significantly influence these phenomena. The heterogeneity can also depend on multiple phases of the landslide activity, responsible for dislodging the whole landslide mass into submasses, each one delimited by secondary scarps and characterized by individual mobility. Hence, in the framework of the European project "MARSite - Marmara Supersite: new directions in seismic hazard assessment through focused Earth observation in the Marmara Supersite", the Büyükçekmece landslide, located approximately 30 km W of Istanbul (Turkey), was considered as a case study. This landslide involves a large mass of approximately 140 million cubic metres, composed of silty clays, tuffs and sands ascribable to Cenozoic geological formations. The landslide is characterized by multiple phases of activity with a composite rototranslational mechanism, which created seven submasses delimited by secondary scarps. The scheme of water circulation in the landslide slope, based on piezometer data as well as on a geological survey, accounts for two flow nets: the first, shallower flow net is located in superficial sandy deposits, outcropping in the dislodged landslide submasses; the second, deeper flow net is located in the main sliding surface. A slope stability analysis following a global limit equilibrium approach provided a distribution of the pseudostatic coefficient vs. pore water pressure. The results show that the stability of the landslide submasses increases moving downslope, and reactivations are expected in the case of earthquakes with a return period between 475 and 2475 yr, according to the local seismic hazard. Dynamic numerical modelling was also performed using the stress

  3. Assessment of landslide hazards resulting from the February 13, 2001, El Salvador earthquake; a report to the government of El Salvador and the U. S. Agency for International Development

    Baum, Rex L.; Crone, Anthony J.; Escobar, Demetreo; Harp, Edwin L.; Major, Jon J.; Martinez, Mauricio; Pullinger, Carlos; Smith, Mark E.

    2001-01-01

    On February 13, 2001, a magnitude 6.5 earthquake occurred about 40 km eastsoutheast of the capital city of San Salvador in central El Salvador and triggered thousands of landslides in the area east of Lago de Ilopango. The landslides are concentrated in a 2,500-km2 area and are particularly abundant in areas underlain by thick deposits of poorly consolidated, late Pleistocene and Holocene Tierra Blanca rhyolitic tephras that were erupted from Ilopango caldera. Drainages in the tephra deposits are deeply incised, and steep valley walls failed during the strong shaking. Many drainages are clogged with landslide debris that locally buries the adjacent valley floor. The fine grain-size of the tephra facilitates its easy mobilization by rainfall runoff. The potential for remobilizing the landslide debris as debris flows and in floods is significant as this sediment is transported through the drainage systems during the upcoming rainy season. In addition to thousands of shallow failures, two very large landslides occurred that blocked the Rio El Desague and the Rio Jiboa. The Rio El Desague landslide has an estimated volume of 1.5 million m3, and the Rio Jiboa landslide has an estimated volume of 12 million m3. Field studies indicate that catastrophic draining of the Rio El Desague landslide-dammed lake would pose a minimal flooding hazard, whereas catastrophic draining of the Rio Jiboa lake would pose a serious hazard and warrants immediate action. Construction of a spillway across part of the dam could moderate the impact of catastrophic lake draining and the associated flood. Two major slope failures on the northern side of Volcan San Vicente occurred in the upper reaches of Quebrada Del Muerto and the Quebrada El Blanco. The landslide debris in the Quebrada Del Muerto consists dominantly of blocks of well-lithified andesite, whereas the debris in the Quebrada El Blanco consists of poorly consolidated pyroclastic sediment. The large blocks of lithified rock in

  4. Earthquake dynamics. Mapping pressurized volcanic fluids from induced crustal seismic velocity drops.

    PubMed

    Brenguier, F; Campillo, M; Takeda, T; Aoki, Y; Shapiro, N M; Briand, X; Emoto, K; Miyake, H

    2014-07-04

    Volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth. Here, we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations. We used records of seismic noise from the Japanese Hi-net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude (M(w)) 9.0 Tohoku-Oki earthquake. We interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves. We suggest, therefore, that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems. Copyright © 2014, American Association for the Advancement of Science.

  5. Experimental research on the dam-break mechanisms of the Jiadanwan landslide dam triggered by the Wenchuan earthquake in China.

    PubMed

    Xu, Fu-gang; Yang, Xing-guo; Zhou, Jia-wen; Hao, Ming-hui

    2013-01-01

    Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation.

  6. Experimental Research on the Dam-Break Mechanisms of the Jiadanwan Landslide Dam Triggered by the Wenchuan Earthquake in China

    PubMed Central

    Xu, Fu-gang; Yang, Xing-guo; Hao, Ming-hui

    2013-01-01

    Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation. PMID:23844387

  7. The importance of earthquake-induced landslides to long-term slope erosion and slope-failure hazards in seismically active regions

    Keefer, D.K.

    1994-01-01

    This paper describes a general method for determining the amount of earthquake-induced landsliding that occurs in a seismically active region over time; this determination can be used as a quantitative measure of the long-term hazard from seismically triggered landslides as well as a measure of the importance of this process to regional slope-erosion rates and landscape evolution. The method uses data from historical earthquakes to relate total volume of landslide material dislodged by an earthquake to the magnitude, M, and seismic moment, M0, of the earthquake. From worldwide data, a linear-regression relation between landslide volume, V, and M0 is determined as: V = M0/1018.9(?? 0.13), where V is measured in m3 and M0 is in dyn-cm. To determine the amount of earthquake-generated landsliding over time, this relation is combined with data on seismic-moment release for a particular region, which may be derived from either earthquake-history or fault-slip data. The form of the M0-V relation allows the rate of production of earthquake-induced landslides over time to be determined from total rate of seismic-moment release without regard to the distribution of individual events, thus simplifying and generalizing the determination. Application of the method to twelve seismically active regions, with areas ranging from 13,275 to 2,308,000 km2, shows that erosion rates from earthquake-induced landslides vary significantly from region to region. Of the regions studied, the highest rates were determined for the island of Hawaii, New Zealand, western New Guinea, and the San Francisco Bay region of California. Significantly lower rates were determined for Iran, Tibet, the Sierra Nevada-Great Basin region of California, and central Japan (for the time period from 715 AD to the present). Intermediate rates were determined for Peru, southern California, onshore California, Turkey, and central Japan (for the time period from 1586 AD to the present). To determine the relative, long

  8. Response of the Laprak Landslide to the 2015 Nepal Earthquake and Implications for the Utility of Simple Infinite Slope Models in Regional Landslide Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Haneberg, W. C.; Gurung, N.

    2016-12-01

    The village of Laprak, located in the Gorkha District of western Nepal, was built on a large colluvium landslide about 10 km from the epicenter of the 25 April 2015 M 7.8 Nepal earthquake. Recent episodic movement began during a wet period in 1999 and continued in at least 2002, 2006, and 2007, destroying 24 homes, removing 23 hectares of land from agricultural production, and claiming 1 life. Reconnaissance mapping, soil sampling and testing, and slope stability analyses undertaken before the 2015 earthquake suggested that the hillside should be stable under dry conditions, unstable to marginally stable under static wet conditions, and wholly unstable under wet seismic conditions. Most of the buildings in Laprak, which were predominantly of dry fitted stone masonry, were destroyed by Intensity IX shaking during the 2015 earthquake. Interpretation of remotely sensed imagery and published photographs shows new landslide features; hence, some downslope movement occurred but the landslide did not mobilize into a long run-out flow. Monte Carlo simulations based upon a pseudostatic infinite slope model and constrained by reasonable distributions of soil shear strength, pore pressure, and slope angle from earlier work and seismic coefficients based upon the observed Intensity IX shaking (and inferred PGA) yield high probabilities of failure for steep portions of the slope above and below the village but moderate probabilities of failure for the more gentle portion of the slope upon which most of the village was constructed. In retrospect, the seismic coefficient selected for the pre-earthquake analysis proved to be remarkably prescient. Similar results were obtained using a first-order, second-moment (FOSM) approach that is convenient for GIS based regional analyses. Predictions of permanent displacement made using a variety of published empirical formulae based upon sliding block analyses range from about 10 cm to about 200 cm, also broadly consistent with the observed

  9. Landslides

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The slumping of materials in the walls of this impact crater illustrate the continued erosion of the martian surface. Small fans of debris as well as larger landslides are observed throughout the THEMIS image.

    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.

    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.

    Image information: VIS instrument. Latitude 40.9, Longitude 120.5 East (239.5 West). 19 meter/pixel resolution.

  10. Experimental Evidence of Volcanic Earthquakes Induced by Different Fluid Types

    NASA Astrophysics Data System (ADS)

    Clarke, J. A.; Adam, L.; Sarout, J.; van Wijk, K.; Dautriat, J. D.; Kennedy, B.

    2017-12-01

    Low Frequency volcanic seismicity has long been associated with resonance in fluid-filled cracks or conduits driven by pressure perturbations at depth. In volcano monitoring, fluid movement, fracturing and the conduit geometry are interpreted based on field observations, laboratory experiments, and numerical models. Fluids in a volcanic environment include gasses, brine and magmas with different viscosities. Magma viscosity is a key influence on eruptive behaviour. For example, increasing magma viscosity is known to favour explosive eruptions. How different fluids affect volcano seismicity is not well understood. Here, we explore the effects of fluid type on volcano seismic signals. Frequency content in the signal, frequency of the events, source mechanism and quality factor are studied. We simulate volcano tectonic (fracturing) and volcano seismic (fluid movement) signatures in a controlled laboratory environment using a range of rock samples, fluid types and pressure conditions. The viscosity of the fluids spans six orders of magnitude, representing realistic volcanic fluids. Microseismicity is generated by venting pressurised fluids through pre-generated fracture networks in cylindrical rock core samples and detected by an array of 18 ultrasonic transducers. We fracture samples of two lithologies: 1) low porosity impermeable granite samples and 2) a permeable volcanic ash tuff sample. Permeability and porosity in the granites are due to a fracture network, while in the tuff a high porosity matrix ( 40 %) and a fracture network interact. The fluids used are nitrogen gas, water, and mixtures of water and glycerol. We generate and detect a myriad of seismic event types, some of which resemble well-known families of volcano-tectonic, low-frequency, hybrid and tremor-type seismicity. Samples with fluids of lower density and viscosity generate a higher number of seismic events. We will present an integrated analysis of the event types, frequency content, source

  11. Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan

    PubMed Central

    Satake, Kenji

    2018-01-01

    Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [Mw (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non–double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of Mzx, Mzy, and M{tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved. PMID:29740604

  12. Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan.

    PubMed

    Fukao, Yoshio; Sandanbata, Osamu; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime; Watada, Shingo; Satake, Kenji

    2018-04-01

    Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [ M w (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non-double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of M zx , M zy , and M {tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved.

  13. The Ust'-Kamchatsk "Tsunami Earthquake" of 13 April 1923: A Slow Event and a Probable Landslide

    NASA Astrophysics Data System (ADS)

    Salaree, A.; Okal, E.

    2016-12-01

    Among the "tsunami earthquakes" having generated a larger tsunami than expected from their seismic magnitudes, the large aftershock of the great Kamchatka earthquake of 1923 remains an intriguing puzzle since waves reaching 11 m were reported by Troshin & Diagilev (1926), in the vicinity of the mouth of the Kamchatka River near the coastal settlement of Ust'-Kamchatsk. Our relocation attempts based on ISS-listed travel times would put the earthquake epicenter in Ozernoye Bay, North of the Kamchatka Peninsula, suggesting that it was triggered by stress transfer beyond the plate junction at the Kamchatka corner. Mantle magnitudes obtained from Golitsyn records at De Bilt suggest a long-period moment of 2-3 times 1027 dyn*cm, with a strong increase of moment with period, suggestive of a slow source. However, tsunami simulations based on resulting models of the earthquake source, both North and South of the Kamchatka Peninsula, fail to account for the reported run-up values. On the other hand, the model of an underwater landslide, which would have been triggered by the earthquake, can explain the general amplitude and distribution of reported run-up. This model is supported by the presence of steep bathymetry offshore of Ust'-Kamchatsk, near the area of discharge of the Kamchatka River, and the abundance of subaerial landslides along the nearby coasts of the Kamchatka Peninsula. While the scarcity of scientific data for this ancient earthquake, and of historical reports in a sparsely populated area, keep this interpretation tentative, this study contributes to improving our knowledge of the challenging family of "tsunami earthquakes".

  14. The Influence of Increasing Rain and Earthquake Activities on Landslide Slope Stability in Forest Areas

    NASA Astrophysics Data System (ADS)

    Kubota, T.; Aditian, A.

    2014-12-01

    Deriving the analysis of rainfall data in various mountainous locations, increase in rainfall that is deemed to be induced by the global climate change is obvious in Kyushu district, western Japan. On this point of view, its long term impact on the forest slope stability is analyzed with field investigation and numerical simulation such as finite element method (FEM). On the other hand, the influence of earthquake such as cracks on the slope due to seismic vibration was also analyzed with FEM. In this case, the slope stability analysis to obtain the factor of safety "Fs" is conducted. Here, in case of the Fs > 1.0, the slope is stable. In addition, the slope stabilizing effect of the forest mainly due to the roots strength is evaluated on some unstable slopes. Simultaneously, a holistic estimation over landslide groups is conducted by comparing "Fs" on forest slopes with non- forest slopes. Therefore, the following conclusions are obtained: 1) Comparing the Fs without increased rainfall from the previous decade and the one with actual rainfall, the former case is 1.04 ~1.06 times more stable than the latter. 2) On the other hand, the forest slopes are estimated to be up to approximately 1.5 to 2.5 times more stable than the slope without forest. Therefore, the slope stabilizing effect by the forest is much higher than the increasing rainfall influence i.e. the climate change effect. These results imply that an appropriate forest existence is important under the climate change condition to prevent forest slope degradation. 3) Comparing with the destabilization of the slope by seismic activities (vibration) due to the reduction of soil strength and "cracks = slope deformation" (8~9 % to 30% reduction in Fs even after an earthquake of 490gal), the influence of the long term rainfall increase on slopes (such as 1% decrease in Fs) is relatively small in the study area.

  15. Effects of gravel on infiltration, runoff, and sediment yield in landslide deposit slope in Wenchuan earthquake area, China.

    PubMed

    Li, Tianyang; He, Binghui; Chen, Zhanpeng; Zhang, Yi; Liang, Chuan; Wang, Renxin

    2016-06-01

    Amounts of landslide deposits were triggered by the Wenchuan earthquake with magnitude 8.0 on May 12, 2008. The landslide deposits were composed of soil and rock fragments, which play important roles in hydrological and erosion processes in the steep slope of landslide deposits. The mixtures of soil and gravels are common in the top layers of landslide deposits, and its processes are obviously different with the soil without gravels. Based on the data of field investigation, a series of simulated scouring flow experiments with four proportion of gravel (0, 25, 33.3, and 50 %) and three scouring flow rates (4, 8, 12 L/min) under two steep slopes (67.5, 72.7 %) were conducted sequentially to know the effects of proportion of gravel on infiltration capacity, runoff generation, and sediment production in the steep slope of landslide deposit. Results indicated that gravel had promoted or reduced effects on infiltration capacity which could affect further the cumulative runoff volume and cumulative sediment mass increase or decrease. The cumulative infiltration volume in 25 % proportion of gravel was less than those in 0, 33.3, and 50 % proportion of gravel. The cumulative runoff volume was in an order of 25 > 0 > 33.3 > 50 % while cumulative sediment mass ranked as 25 > 33.3 > 0 > 50 % with different proportions of gravel. A significant power relationship was found between scouring time and cumulative runoff volume as well as cumulative sediment mass. The relationship between average soil and water loss rate and proportion of gravel was able to express by quadratic function, with a high degree of reliability. The results have important implications for soil and water conservation and modeling in landslide deposit but also provide useful information for the similar conditions.

  16. Do submarine landslides and turbidites provide a faithful record of large magnitude earthquakes in the Western Mediterranean?

    NASA Astrophysics Data System (ADS)

    Clare, Michael

    2016-04-01

    Large earthquakes and associated tsunamis pose a potential risk to coastal communities. Earthquakes may trigger submarine landslides that mix with surrounding water to produce turbidity currents. Recent studies offshore Algeria have shown that earthquake-triggered turbidity currents can break important communication cables. If large earthquakes reliably trigger landslides and turbidity currents, then their deposits can be used as a long-term record to understand temporal trends in earthquake activity. It is important to understand in which settings this approach can be applied. We provide some suggestions for future Mediterranean palaeoseismic studies, based on learnings from three sites. Two long piston cores from the Balearic Abyssal Plain provide long-term (<150 ka) records of large volume turbidites. The frequency distribution form of turbidite recurrence indicates a constant hazard rate through time and is similar to the Poisson distribution attributed to large earthquake recurrence on a regional basis. Turbidite thickness varies in response to sea level, which is attributed to proximity and availability of sediment. While mean turbidite recurrence is similar to the seismogenic El Asnam fault in Algeria, geochemical analysis reveals not all turbidites were sourced from the Algerian margin. The basin plain record is instead an amalgamation of flows from Algeria, Sardinia, and river fed systems further to the north, many of which were not earthquake-triggered. Thus, such distal basin plain settings are not ideal sites for turbidite palaoeseimology. Boxcores from the eastern Algerian slope reveal a thin silty turbidite dated to ~700 ya. Given its similar appearance across a widespread area and correlative age, the turbidite is inferred to have been earthquake-triggered. More recent earthquakes that have affected the Algerian slope are not recorded, however. Unlike the central and western Algerian slopes, the eastern part lacks canyons and had limited sediment

  17. Landslides triggered by an earthquake and heavy rainfalls at Aso volcano, Japan, detected by UAS and SfM-MVS photogrammetry

    NASA Astrophysics Data System (ADS)

    Saito, Hitoshi; Uchiyama, Shoichiro; Hayakawa, Yuichi S.; Obanawa, Hiroyuki

    2018-12-01

    Unmanned aerial systems (UASs) and structure-from-motion multi-view stereo (SfM-MVS) photogrammetry have attracted a tremendous amount of interest for use in the creation of high-definition topographic data for geoscientific studies. By using these techniques, this study examined the topographic characteristics of coseismic landslides triggered by the 2016 Kumamoto earthquake (Mw 7.1) in the Sensuikyo area (1.0 km2) at Aso volcano, Japan. The study area has frequently experienced rainfall-induced landslide events, such as those in 1990, 2001, and 2012. We obtained orthorectified images and digital surface models (DSMs) with a spatial resolution of 0.06 m before and after the 2016 Kumamoto earthquake. By using these high-definition images and DSMs, we detected a total of 54 coseismic landslides with volumes of 9.1-3994.6 m3. These landslides, many of which initiated near topographic ridges, were typically located on upside hillslopes of previous rainfall-induced landslide scars that formed in 2012. This result suggests that the topographic effect on seismic waves, i.e., amplification of ground acceleration, was important for coseismic landslide initiation in the study area. The average depth of the coseismic landslides was 1.5 m, which is deeper than the depth of the rainfall-induced landslides prior to these. The total sediment production of the coseismic landslides reached 2.5 × 104 m3/km2, which is of the same order as the sediment production triggered by the previous single heavy rainfall event. This result indicates that the effects of the 2016 Kumamoto earthquake in terms of sediment production and topographic changes were similar to those of the rainfall-induced landslide event in the study area.

  18. Initiation and runaway process of Tsaoling landslide, triggered by the 1999 Taiwan Chi-Chi earthquake, as studied by high-velocity friction experiments (Invited)

    NASA Astrophysics Data System (ADS)

    Togo, T.; Shimamoto, T.; Dong, J.; Lee, C.

    2013-12-01

    High-velocity friction experiments in the last two decades have demonstrated dramatic weakening of simulated faults at seismic slip rates on the order of 1 m/s (e.g., Di Toro et al., 2011, Nature). Similar experiments revealed very low friction of landslide materials (0.05-0.2 in friction coefficient) that can cause catastrophic landslides with velocity exceeding even 10 m/s (e.g., Miyamoto et al. (2009) on the 1999 Tsaoling landslide in Taiwan; Yano et al. (2009) on the 1999 Jiufengershan landslide in Taiwan,; Ferri et al. (2010, 2011) on the 1963 Vaiont landslide in Italy; Kuo et al. (2011) on the 2009 Hsiaolin landslide in Taiwan). Those studies strongly suggest that there are common processes operative in fault zones and along slip surfaces of catastrophic landslides along bedding planes, fractures or joints. As for catastrophic landslides triggered by an earthquake, an important issue to be addressed is how a landslide initiates during seismic ground motion. Thus we have studied the initiation and runaway process of the Tsaoling landslide by idealizing the initial landslide movement during seismic ground motion as an oscillating accelerating/decelerating motion. Tsaoling landslide is the largest landslide among those triggered by the Chi-Chi earthquake with its volume of about 130 Mm3. The landslide took place along very planar bedding planes of the porous Pliocene sedimentary rocks (mostly siltstone and sandstone), with a dip angle of 14 degree. A seismic record at a station about 500 m away from the landslide and a witness of a survivor who slid on top of the landslide mass indicate that the average speed of the landslide reached 20~40 m/s. A simple analysis of sliding block indicates that the kinetic friction has to be 0.05~0.15 to produce such a high-velocity. Moreover, Tang et al. (2009, Eng. Geol.) analyzed landslide motion with the discrete element method and showed that the landslide mass must have slid nearly as an intact mass, without much

  19. Modelling the Time Dependence of Frequency Content of Long-period Volcanic Earthquakes

    NASA Astrophysics Data System (ADS)

    Jousset, P.; Neuberg, J. W.

    2001-12-01

    Broad-band seismic networks provide a powerfull tool for the observation and analysis of volcanic earthquakes. The amplitude spectrogram allows us to follow the frequency content of these signals with time. Observed amplitude spectrograms of long-period volcanic earthquakes display distinct spectral lines sometimes varying by several Hertz over time spans of minutes to hours. We first present several examples associated with various phases of volcanic activity at Soufrière Hills volcano, Montserrat. Then, we present and discuss two mechanisms to explain such frequency changes in the spectrograms: (i) change of physical properties within the magma and, (ii) change in the triggering frequency of repeated sources within the conduit. We use 2D and 3D finite-difference modelling methods to compute the propagation of seismic waves in simplified volcanic structures: (i) we model the gliding spectral lines by introducing continuously changing magma properties during the wavefield computation; (ii) we explore the resulting pressure distribution within the conduit and its potential role in triggering further events. We obtain constraints on both amplitude and time-scales for changes of magma properties that are required to model gliding lines in amplitude spectrograms.

  20. Advancements in near real time mapping of earthquake and rainfall induced landslides in the Avcilar Peninsula, Marmara Region

    NASA Astrophysics Data System (ADS)

    Coccia, Stella

    2014-05-01

    Stella COCCIA (1), Fiona THEOLEYRE (1), Pascal BIGARRE(1) , Semih ERGINTAV(2), Oguz OZEL(3) and Serdar ÖZALAYBEY(4) (1) National Institute of Industrial Environment and Risks (INERIS) Nancy, France, (2) Kandilli Observatory and Earthquake Research Institute (KOERI), Istanbul, Turkey, (3) Istanbul University (IU), Istanbul, Turkey, (4) TUBITAK MAM, Istanbul, Turkey The European Project MARsite (http://marsite.eu/), started in 2012 and leaded by the KOERI, aims to improve seismic risk evaluation and preparedness to face the next dreadful large event expected for the next three decades. MARsite is thus expected to move a "step forward" the most advanced monitoring technologies, and offering promising open databases to the worldwide scientific community in the frame of other European environmental large-scale infrastructures, such as EPOS (http://www.epos-eu.org/ ). Among the 11 work packages (WP), the main aim of the WP6 is to study seismically-induced landslide hazard, by using and improving observing and monitoring systems in geological, hydrogeotechnical and seismic onshore and offshore areas. One of the WP6 specific study area is the Avcilar Peninsula, situated between Kucukcekmece and Buyukcekmece Lakes in the north-west of the region of Marmara. There, more than 400 landslides are located. According to geological and geotechnical investigations and studies, soil movements of this area are related to underground water and pore pressure changes, seismic forces arising after earthquakes and decreasing sliding strength in fissured and heavily consolidated clays. The WP6 includes various tasks and one of these works on a methodology to develop a dynamic system to create combined earthquake and rainfall induced landslides hazard maps at near real time and automatically. This innovative system could be used to improve the prevention strategy as well as in disaster management and relief operations. Base on literature review a dynamic GIS platform is used to combine

  1. Analysis on Two Typical Landslide Hazard Phenomena in The Wenchuan Earthquake by Field Investigations and Shaking Table Tests.

    PubMed

    Yang, Changwei; Zhang, Jianjing; Liu, Feicheng; Bi, Junwei; Jun, Zhang

    2015-08-06

    Based on our field investigations of landslide hazards in the Wenchuan earthquake, some findings can be reported: (1) the multi-aspect terrain facing empty isolated mountains and thin ridges reacted intensely to the earthquake and was seriously damaged; (2) the slope angles of most landslides was larger than 45°. Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes. The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°. The amplification along the slope strike direction is basically consistent, and the step is smooth.

  2. Analysis on Two Typical Landslide Hazard Phenomena in The Wenchuan Earthquake by Field Investigations and Shaking Table Tests

    PubMed Central

    Yang, Changwei; Zhang, Jianjing; Liu, Feicheng; Bi, Junwei; Jun, Zhang

    2015-01-01

    Based on our field investigations of landslide hazards in the Wenchuan earthquake, some findings can be reported: (1) the multi-aspect terrain facing empty isolated mountains and thin ridges reacted intensely to the earthquake and was seriously damaged; (2) the slope angles of most landslides was larger than 45°. Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes. The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°. The amplification along the slope strike direction is basically consistent, and the step is smooth. PMID:26258785

  3. Observations and recommendations regarding landslide hazards related to the January 13, 2001 M-7.6 El Salvador earthquake

    Jibson, Randall W.; Crone, Anthony J.

    2001-01-01

    The January 13, 2001 earthquake (M-7.6) off the coast of El Salvador triggered widespread damaging landslides in many parts of the El Salvador. In the aftermath of the earthquake, the Salvadoran government requested technical assistance through the U.S. Agency for International Development (USAID); USAID, in turn, requested help from technical experts in landslide hazards from the U.S. Geological Survey. In response to that request, we arrived in El Salvador on January 31, 2001 and worked with USAID personnel and Salvadoran agency counterparts in visiting landslide sites and evaluating present and potential hazards. A preliminary, unofficial report was prepared at the end of our trip (February 9) to provide immediate information and assistance to interested agencies and parties. The current report is an updated and somewhat expanded version of that unofficial report. Because of the brief nature of this report, conclusions and recommendations contained herein should be considered tentative and may be revised in the future.

  4. The role of the 2008 Mw 7.9 Wenchuan earthquake in topographic evolution: seismically induced landslides and the associated isostatic response

    NASA Astrophysics Data System (ADS)

    Ren, Z.; Zhang, Z.; Zhang, H.; Zheng, W.; Zhang, P. Z.

    2017-12-01

    The widely held understanding that reverse-faulting earthquakes play an important role in building mountains has been challenged by recent studies suggesting that co-seismic landslides of the 2008 Mw 7.9 Wenchuan earthquake led to a net co-seismic lowering of surface height. We use precise estimates of co-seismic landslide volumes to calculate the long-term isostatic response to landsliding during the 2008 Wenchuan earthquake. The total isostatic respond volume is 2.0 km3 which did not change much associated with thickness of Te, however, the distribution of the rebound changes associated with thickness of Te. The total co-seismic mass change could be 1.8 km3. The maximum isostatic response due to Wenchuan earthquake may have been as high as 0.9 meters in the highest Pengguan massif of the central Longmen Shan. We also find that the average net uplift is 0.16 meters within the total landslide region due to the Wenchuan earthquake. Our findings suggest that the local topographic evolution of the middle Longmen Shan region is closely related to repeated tectonic events such as the 2008 Wenchuan Earthquake.

  5. The Pliocene Horcón Formation, Central Chile: a case study of earthquake-induced landslide susceptibility

    NASA Astrophysics Data System (ADS)

    Valdivia, D.; Elgueta, S.; Hodgkin, A.; Marquardt, C.; del Valle, F.; Yáñez Morroni, G.

    2017-12-01

    Stability slope analysis is typically focused on modeling using cohesion and friction angle parameters but in earthquake-induced landslides, susceptibility is correlated more to lithological and stratigraphic parameters. In sedimentary deposits whose cohesion and diagenesis are very low, the risk of landslides increases. The Horcón Formation, which crops out continuously along cliffs in Central Chile between 32.5° and 33°S, is a Miocene-Pliocene well preserved, horizontally stratified unit composed of marine strata which overlies Paleozoic-Mesozoic igneous basement. During the Quaternary, the sequence was tectonically uplifted 80 meters and covered by unconsolidated eolian deposits. Given that Seismotectonic and Barrier-Asperity models suggest the occurrence of a forthcoming megathrust earthquake in a segment which includes this area, the Horcón Formation constitutes a good case study to characterize the susceptibility of this type of sediment for mass movements triggered by earthquakes. Field mapping, stratigraphic and sedimentological studies, including petrographic analyses to determine lithological composition and paragenesis of diagenetic events, have been carried out along with limited gravimetric profiling and CPTU drill tests. High resolution digital elevation modeling has also been applied. This work has led to the recognition of a shallow marine lithofacies association composed of weakly lithified fossiliferous and bioturbated medium to fine grained litharenite, mudstone, and fine conglomerate. The low grade of diagenesis in the sedimentary deposits was in response to a short period of burial and a subsequent accelerated uplift evidenced along the coast of Chile during the Quaternary. We have generated a predictive model of landslide susceptibility for the Horcón Formation and for the overlying Quaternary eolian deposits incorporating variables such as composition and diagenesis of lithofacies, slope, structures, weathering and landcover. The model

  6. The 2007 Nazko, British Columbia, earthquake sequence: Injection of magma deep in the crust beneath the Anahim volcanic belt

    Cassidy, J.F.; Balfour, N.; Hickson, C.; Kao, H.; White, Rickie; Caplan-Auerbach, J.; Mazzotti, S.; Rogers, Gary C.; Al-Khoubbi, I.; Bird, A.L.; Esteban, L.; Kelman, M.; Hutchinson, J.; McCormack, D.

    2011-01-01

    On 9 October 2007, an unusual sequence of earthquakes began in central British Columbia about 20 km west of the Nazko cone, the most recent (circa 7200 yr) volcanic center in the Anahim volcanic belt. Within 25 hr, eight earthquakes of magnitude 2.3-2.9 occurred in a region where no earthquakes had previously been recorded. During the next three weeks, more than 800 microearthquakes were located (and many more detected), most at a depth of 25-31 km and within a radius of about 5 km. After about two months, almost all activity ceased. The clear P- and S-wave arrivals indicated that these were high-frequency (volcanic-tectonic) earthquakes and the b value of 1.9 that we calculated is anomalous for crustal earthquakes but consistent with volcanic-related events. Analysis of receiver functions at a station immediately above the seismicity indicated a Moho near 30 km depth. Precise relocation of the seismicity using a double-difference method suggested a horizontal migration at the rate of about 0:5 km=d, with almost all events within the lowermost crust. Neither harmonic tremor nor long-period events were observed; however, some spasmodic bursts were recorded and determined to be colocated with the earthquake hypocenters. These observations are all very similar to a deep earthquake sequence recorded beneath Lake Tahoe, California, in 2003-2004. Based on these remarkable similarities, we interpret the Nazko sequence as an indication of an injection of magma into the lower crust beneath the Anahim volcanic belt. This magma injection fractures rock, producing high-frequency, volcanic-tectonic earthquakes and spasmodic bursts.

  7. An Account of Preliminary Landslide Damage and Losses Resulting from the February 28, 2001, Nisqually, Washington, Earthquake

    Highland, Lynn M.

    2003-01-01

    The February 28, 2001, Nisqually, Washington, earthquake (Mw = 6.8) damaged an area of the northwestern United States that previously experienced two major historical earthquakes, in 1949 and in 1965. Preliminary estimates of direct monetary losses from damage due to earthquake-induced landslides is approximately $34.3 million. However, this figure does not include costs from damages to the elevated portion of the Alaskan Way Viaduct, a major highway through downtown Seattle, Washington that will be repaired or rebuilt, depending on the future decision of local and state authorities. There is much debate as to the cause of the damage to this viaduct with evaluations of cause ranging from earthquake shaking and liquefaction to lateral spreading to a combination of these effects. If the viaduct is included in the costs, the losses increase to $500+ million (if it is repaired) or to more than $1+ billion (if it is replaced). Preliminary estimate of losses due to all causes of earthquake damage is approximately $2 billion, which includes temporary repairs to the Alaskan Way Viaduct. These preliminary dollar figures will no doubt increase when plans and decisions regarding the Viaduct are completed.

  8. On Correlational Properties for Volcanic Earthquakes Associated with Asamayama (Japan), 1983-2005

    SciT

    Reyment, Richard A.

    To a first approximation, earthquakes directly associated with volcanic activity may be studied as point-stochastic processes. The earthquakes associated with B-type (movements located at 1 km or shallower) eruptive activity in the caldera of Asamayama differ in correlational properties from concurrent deep-seated seismic activity (A-type, located deeper than approximately 1 km). A-type activity occurs either in the form of independently distributed intervals between events or as dependently distributed intervals which are most appropriately analysed in contiguous sub-samples ('windows'). The cross correlations between the magnitudes of A-type earthquakes and depth of events for three periods from 1983 to 2005 may bemore » of significance for interpreting aspects of the volcanic history of Asamayama. The lag-1 serial correlation coefficient for the A-type sequence from 1983 to 1990 is not significantly different from zero. In the case of the sets for 1991-2002 and 2003-2005, the coefficients are small but not zero. The difference is in part, at least, probably due to the well-known confounding effect of trending as opposed to true serial correlation between successive events. The serial correlation coefficient for the B-type crater sequence is not significant. The novel aspect of the present study concerns the relationship between depth of A-type earth movements and magnitude of associated shocks.« less

  9. Water and soil loss from landslide deposits as a function of gravel content in the Wenchuan earthquake area, China, revealed by artificial rainfall simulations.

    PubMed

    Gan, Fengling; He, Binghui; Wang, Tao

    2018-01-01

    A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China.

  10. Water and soil loss from landslide deposits as a function of gravel content in the Wenchuan earthquake area, China, revealed by artificial rainfall simulations

    PubMed Central

    Gan, Fengling; Wang, Tao

    2018-01-01

    A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China. PMID:29723279

  11. Tsunami Source Modeling of the 2015 Volcanic Tsunami Earthquake near Torishima, South of Japan

    NASA Astrophysics Data System (ADS)

    Sandanbata, O.; Watada, S.; Satake, K.; Fukao, Y.; Sugioka, H.; Ito, A.; Shiobara, H.

    2017-12-01

    the physical mechanism of the 2015 Torishima earthquake. First, the estimated large uplift within Smith Caldera implies the earthquake may be related to some volcanic activity of the caldera. Secondly, the modeled ring of subsidence surrounding the caldera suggests that the process may have included notable subsidence, at least on the northeastern side out of the caldera.

  12. Integrating landslide and liquefaction hazard and loss estimates with existing USGS real-time earthquake information products

    Allstadt, Kate E.; Thompson, Eric M.; Hearne, Mike; Nowicki Jessee, M. Anna; Zhu, J.; Wald, David J.; Tanyas, Hakan

    2017-01-01

    The U.S. Geological Survey (USGS) has made significant progress toward the rapid estimation of shaking and shakingrelated losses through their Did You Feel It? (DYFI), ShakeMap, ShakeCast, and PAGER products. However, quantitative estimates of the extent and severity of secondary hazards (e.g., landsliding, liquefaction) are not currently included in scenarios and real-time post-earthquake products despite their significant contributions to hazard and losses for many events worldwide. We are currently running parallel global statistical models for landslides and liquefaction developed with our collaborators in testing mode, but much work remains in order to operationalize these systems. We are expanding our efforts in this area by not only improving the existing statistical models, but also by (1) exploring more sophisticated, physics-based models where feasible; (2) incorporating uncertainties; and (3) identifying and undertaking research and product development to provide useful landslide and liquefaction estimates and their uncertainties. Although our existing models use standard predictor variables that are accessible globally or regionally, including peak ground motions, topographic slope, and distance to water bodies, we continue to explore readily available proxies for rock and soil strength as well as other susceptibility terms. This work is based on the foundation of an expanding, openly available, case-history database we are compiling along with historical ShakeMaps for each event. The expected outcome of our efforts is a robust set of real-time secondary hazards products that meet the needs of a wide variety of earthquake information users. We describe the available datasets and models, developments currently underway, and anticipated products. 

  13. Residual shear strength variability as a primary control on movement of landslides reactivated by earthquake-induced ground motion: Implications for coastal Oregon, U.S.

    Schulz, William H.; Wang, Gonghui

    2014-01-01

    Most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition. Residual shear strength often varies during rapid displacement, but the response of residual shear zones to seismic loading is largely unknown. We used a ring shear apparatus to perform simulated seismic loading tests, constant displacement rate tests, and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coseismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coseismic failure. The landslides we studied represent many along the Oregon, U.S., coast. Seismic loading tests resulted in (1) catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and (2) limited to unbounded displacement when stresses represented those for hypothetical dormant landslides, suggesting that coseismic landslide reactivation may be significant during future great earthquakes occurring near the Oregon Coast. Constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0.001 cm s−1 or greater. Dynamic shear resistance estimated from shear strength models correlated well with stresses observed during seismic loading tests, indicating that displacement rate and amount primarily controlled failure characteristics. We developed a stress-based approach to estimate coseismic landslide displacement that utilizes the variable shear strength model. The approach produced results that compared favorably to observations made during seismic loading tests, indicating its utility for application to landslides.

  14. Period doubling and other nonlinear phenomena in volcanic earthquakes and tremor

    Julian, B.R.

    2000-01-01

    Evidence of subharmonic period-doubling cascades has recently been recognized in seismograms of volcanic tremor from several volcanoes. This phenomenon occurs only in nonlinear systems, and is the commonest route by which such systems change from periodic to chaotic behavior. It is predicted to occur in a model of volcanic tremor excitation by flow-induced vibration, and it might well also occur in other volcano-seismic source process. If the possibility of period doubling is not taken into account in interpreting spectra of tremor and long-period earthquakes, then low-frequency "sub-harmonic" oscillations may be mis-identified as normal modes of a linear acoustic resonator, leading to errors of an order of magnitude or more in inferred magma-body dimensions. This example illustrates the importance of nonlinear phenomena in attempts to understand volcano-seismic phenomena physically. Linear systems are fundamentally incapable of causing earthquakes or exciting tremor, so nonlinearity is essential to any theory of volcano-seismic phenomena. Nonlinear processes are in many respects qualitatively different from linear ones. A few of their characteristics that might be relevant in volcanoes include the possibility: (1) that damping might increase, rather than decrease, oscillation frequencies; and (2) that these frequencies might be functions of the amplitude of oscillation, so that temporal variations in spectral peak frequencies might not be manifestations of changes of conditions within the magmatic system.

  15. The 2016 Kumamoto-Oita earthquake sequence: aftershock seismicity gap and dynamic triggering in volcanic areas

    NASA Astrophysics Data System (ADS)

    Uchide, Takahiko; Horikawa, Haruo; Nakai, Misato; Matsushita, Reiken; Shigematsu, Norio; Ando, Ryosuke; Imanishi, Kazutoshi

    2016-11-01

    The 2016 Kumamoto-Oita earthquake sequence involving three large events ( M w ≥ 6) in the central Kyushu Island, southwest Japan, activated seismicities in two volcanic areas with unusual and puzzling spatial gaps after the largest earthquake ( M w 7.0) of April 16, 2016. We attempt to reveal the seismic process during the sequence by following seismological data analyses. Our hypocenter relocation result implies that the large events ruptured different faults of a complex fault system. A slip inversion analysis of the largest event indicates a large slip in the seismicity gap (Aso gap) in the caldera of Mt. Aso, which probably released accumulated stress and resulted in little aftershock production. We identified that the largest event dynamically triggered a mid-M6 event at Yufuin (80 km northeast of the epicenter), which is consistent with existence of the 20-km long zone where seismicity was activated and surface offset was observed. These findings will help us study the contribution of the identified complexity in fault geometries and the geotherm in the volcanic areas to the revealed seismic process and consequently improve our understanding of the seismo-volcano tectonics.[Figure not available: see fulltext.

  16. Influence of surface-normal ground acceleration on the initiation of the Jih-Feng-Erh-Shan landslide during the 1999 Chi-Chi, Taiwan, earthquake

    Huang, C.-C.; Lee, Y.-H.; Liu, Huaibao P.; Keefer, D.K.; Jibson, R.W.

    2001-01-01

    The 1999 Chi-Chi, Taiwan, earthquake triggered numerous landslides throughout a large area in the Central Range, to the east, southeast, and south of the fault rupture. Among them are two large rock avalanches, at Tsaoling and at Jih-Feng-Erh-Shan. At Jih-Feng-Erh-Shan, the entire thickness (30-50 m) of the Miocene Changhukeng Shale over an area of 1 km2 slid down its bedding plane for a distance of about 1 km. Initial movement of the landslide was nearly purely translational. We investigate the effect of surface-normal acceleration on the initiation of the Jih-Feng-Erh-Shan landslide using a block slide model. We show that this acceleration, currently not considered by dynamic slope-stability analysis methods, significantly influences the initiation of the landslide.

  17. Assessing the likelihood of volcanic eruption through analysis of volcanotectonic earthquake fault plane solutions

    NASA Astrophysics Data System (ADS)

    Roman, D. C.; Neuberg, J.; Luckett, R. R.

    2006-08-01

    Episodes of volcanic unrest do not always lead to an eruption. Many of the commonly monitored signals of volcanic unrest, including surface deformation and increased degassing, can reflect perturbations to a deeper magma storage system, and may persist for years without accompanying eruptive activity. Signals of volcanic unrest can also persist following the end of an eruption. Furthermore, the most reliable eruption precursor, the occurrence of low-frequency seismicity, appears to reflect very shallow processes and typically precedes eruptions by only hours to days. Thus, the identification of measurable and unambiguous indicators that are sensitive to changes in the mid-level conduit system during an intermediate stage of magma ascent is of critical importance to the field of volcano monitoring. Here, using data from the ongoing eruption of the Soufrière Hills Volcano, Montserrat, we show that ˜90° changes in the orientation of double-couple fault-plane solutions for high-frequency 'volcanotectonic' (VT) earthquakes reflect pressurization of the mid-level conduit system prior to eruption and may precede the onset of eruptive episodes by weeks to months. Our results demonstrate that, once the characteristic stress field response to magma ascent at a given volcano is established, a relatively simple analysis of VT fault-plane solutions may be used to make intermediate-term assessments of the likelihood of future eruptive activity.

  18. Earthquake and Volcanic Hazard Mitigation and Capacity Building in Sub-Saharan Africa

    NASA Astrophysics Data System (ADS)

    Ayele, A.

    2012-04-01

    The East African Rift System (EARS) is a classic example of active continental rifting, and a natural laboratory setting to study initiation and early stage evolution of continental rifts. The EARS is at different stages of development that varies from relatively matured rift (16 mm/yr) in the Afar to a weakly extended Okavango Delta in the south with predicted opening velocity < 3 mm/yr. Recent studies in the region helped researchers to highlight the length and timescales of magmatism and faulting, the partitioning of strain between faulting and magmatism, and their implications for the development of along-axis segmentation. Although the human resource and instrument coverage is sparse in the continent, our understanding of rift processes and deep structure has improved in the last decade after the advent of space geodesy and broadband seismology. The recent major earthquakes, volcanic eruptions and mega dike intrusions that occurred along the EARS attracted several earth scientist teams across the globe. However, most African countries traversed by the rift do not have the full capacity to monitor and mitigate earthquake and volcanic hazards. Few monitoring facilities exist in some countries, and the data acquisition is rarely available in real-time for mitigation purpose. Many sub-Saharan Africa governments are currently focused on achieving the millennium development goals with massive infrastructure development scheme and urbanization while impending natural hazards of such nature are severely overlooked. Collaborations with overseas researchers and other joint efforts by the international community are opportunities to be used by African institutions to best utilize limited resources and to mitigate earthquake and volcano hazards.

  19. Landslides and mass wasting offshore Sumatra - results from the Sumatra Earthquake HMS Scott survey January-February 2005

    NASA Astrophysics Data System (ADS)

    Tappin, D. R.; Henstock, T.; McNeill, L.; Grilli, S.; Biscontin, G.; Watts, P.

    2005-12-01

    Earthquakes are a commonly cited mechanism for triggering submarine landslides that have the potential to generate damaging tsunamis (e.g. Papua New Guinea 1998). Notwithstanding, the Indian Ocean earthquake of December 26th 2005 has been cited as the cause of both far field and local tsunami runups that have been measured at over 35 metres on the west coast of Sumatra. On the basis of present modelling this seems to be the case. However, if earthquakes are such a common trigger for landslides then the magnitude 9.3 earthquake of December 26th might be expected to have caused numerous seabed failures within the area of rupture that may have contributed to local tsunami runup. This contribution discusses the seabed morphology offshore of Sumatra acquired during the survey carried out by HMS Scott in January and February 2005. Utilising a unique high resolution 12 kHz, 361-beam hull-mounted Sass IV sonar, over 40,000 square kilometres of seabed were mapped. The objective was to identify seabed movements that were the result of the earthquake and to identify submarine slope failures that may have contributed to the tsunami. This paper reports on the results of the survey using Fledermaus imaging software. The area mapped is an accretionary complex formed as the two plates have converged over the past 40 million years. From the data several seabed failure mechanisms of different ages have been identified. Along the plate margin in the west of the survey area the deformation front comprises a series of young thrust folds up to 1000m in elevation and tens of kilometres in length. In places the seaward faces of these folds have failed cohesively and slumped blocks 100's of metres high and up to several kilometres long have been displaced up to 13 kilometres onto the inner trench floor. At other locations older episodes of failure are identified by the presence of displaced slumped blocks located on the crests of the folds; the slumps thus predating uplift. Where young

  20. Impact of sea-level rise on earthquake and landslide triggering offshore the Alentejo margin (SW Iberia)

    NASA Astrophysics Data System (ADS)

    Neves, M. C.; Roque, C.; Luttrell, K. M.; Vázquez, J. T.; Alonso, B.

    2016-12-01

    Earthquakes and submarine landslides are recurrent and widespread manifestations of fault activity offshore SW Iberia. The present work tests the effects of sea-level rise on offshore fault systems using Coulomb stress change calculations across the Alentejo margin. Large-scale faults capable of generating large earthquakes and tsunamis in the region, especially NE-SW trending thrusts and WNW-ESE trending dextral strike-slip faults imaged at basement depths, are either blocked or unaffected by flexural effects related to sea-level changes. Large-magnitude earthquakes occurring along these structures may, therefore, be less frequent during periods of sea-level rise. In contrast, sea-level rise promotes shallow fault ruptures within the sedimentary sequence along the continental slope and upper rise within distances of <100 km from the coast. The results suggest that the occurrence of continental slope failures may either increase (if triggered by shallow fault ruptures) or decrease (if triggered by deep fault ruptures) as a result of sea-level rise. Moreover, observations of slope failures affecting the area of the Sines contourite drift highlight the role of sediment properties as preconditioning factors in this region.

  1. New contributions to the debate on the cause of the January 11th, 1693 tsunami in eastern Sicily (Italy): earthquake or offshore landslide source (or may be both)?

    NASA Astrophysics Data System (ADS)

    Armigliato, A.; Tinti, S.; Zaniboni, F.; Pagnoni, G.; Argnani, A.

    2007-12-01

    Eastern Sicily is among the most exposed regions in Italy and in the whole Mediterranean to tsunami hazard and risk. The historical tsunamis recorded here were generally associated to moderate-to-large magnitude earthquakes. The largest tsunami documented in the area occurred on January 11th, 1693. It followed the highest-magnitude earthquake (7.4) of the Italian seismic history. The tsunami, whose first significant motion was a retreat along the entire eastern Sicily coastline, produced the most devastating effects at Augusta (15 meters run-up) and Catania, being relevant at Siracusa and Messina too. A lively debate exists on whether the earthquake was the only source of the tsunami, or other causes (such as submarine landslides, possibly triggered by the earthquake) contributed to the tsunami generation. In the framework of the EC funded project TRANSFER, we investigate both hypotheses, starting from suitable onshore and offshore faults as well as from offshore landslide bodies, and hence simulating numerically the ensuing tsunami and comparing the results with the available historical information. We base on the results obtained during recent offshore surveys, in particular the multichannel seismic survey MESC2001, carried out in year 2001 on board the R/V Urania of the Italian National Council of Researches (CNR), which mapped both active normal faults and a number of possible landslide bodies along the Hyblaean-Malta escarpment, the most prominent tectonic structure found just few kilometres offshore eastern Sicily. From the modelling point of view, the initial condition for the earthquake- generated tsunamis coincides with the vertical coseismic deformation of the seafloor. Instead, the landslide motion is simulated through the Lagrangian block model UBO-BLOCK2, developed at the University of Bologna. Finally, the finite-element code UBO-TSUFE, implemented by the same research team, is used to simulate the tsunami generation and propagation. The main

  2. Modelling the time-dependent frequency content of low-frequency volcanic earthquakes

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Neuberg, Jürgen; Sturton, Susan

    2003-11-01

    Low-frequency volcanic earthquakes and tremor have been observed on seismic networks at a number of volcanoes, including Soufrière Hills volcano on Montserrat. Single events have well known characteristics, including a long duration (several seconds) and harmonic spectral peaks (0.2-5 Hz). They are commonly observed in swarms, and can be highly repetitive both in waveforms and amplitude spectra. As the time delay between them decreases, they merge into tremor, often preceding critical volcanic events like dome collapses or explosions. Observed amplitude spectrograms of long-period volcanic earthquake swarms may display gliding lines which reflect a time dependence in the frequency content. Using a magma-filled dyke embedded in a solid homogeneous half-space as a simplified volcanic structure, we employ a 2D finite-difference method to compute the propagation of seismic waves in the conduit and its vicinity. We successfully replicate the seismic wave field of a single low-frequency event, as well as the occurrence of events in swarms, their highly repetitive characteristics, and the time dependence of their spectral content. We use our model to demonstrate that there are two modes of conduit resonance, leading to two types of interface waves which are recorded at the free surface as surface waves. We also demonstrate that reflections from the top and the bottom of a conduit act as secondary sources that are recorded at the surface as repetitive low-frequency events with similar waveforms. We further expand our modelling to account for gradients in physical properties across the magma-solid interface. We also expand it to account for time dependence of magma properties, which we implement by changing physical properties within the conduit during numerical computation of wave propagation. We use our expanded model to investigate the amplitude and time scales required for modelling gliding lines, and show that changes in magma properties, particularly changes in the

  3. Earthquake-triggered landslides along the Hyblean-Malta Escarpment (off Augusta, eastern Sicily, Italy) - assessment of the related tsunamigenic potential

    NASA Astrophysics Data System (ADS)

    Ausilia Paparo, Maria; Armigliato, Alberto; Pagnoni, Gianluca; Zaniboni, Filippo; Tinti, Stefano

    2017-02-01

    Eastern Sicily is affected by earthquakes and tsunamis of local and remote origin, which is known through numerous historical chronicles. Recent studies have put emphasis on the role of submarine landslides as the direct cause of the main local tsunamis, envisaging that earthquakes (in 1693 and 1908) did produce a tsunami, but also that they triggered mass failures that were able to generate an even larger tsunami. The debate is still open, and though no general consensus has been found among scientists so far, this research had the merit to attract attention on possible generation of tsunamis by landslides off Sicily. In this paper we investigate the tsunami potential of mass failures along one sector of the Hyblean-Malta Escarpment (HME). facing Augusta. The HME is the main offshore geological structure of the region running almost parallel to the coast, off eastern Sicily. Here, bottom morphology and slope steepness favour soil failures. In our work we study slope stability under seismic load along a number of HME transects by using the Minimun Lithostatic Deviation (MLD) method, which is based on the limit-equilibrium theory. The main goal is to identify sectors of the HME that could be unstable under the effect of realistic earthquakes. We estimate the possible landslide volume and use it as input for numerical codes to simulate the landslide motion and the consequent tsunami. This is an important step for the assessment of the tsunami hazard in eastern Sicily and for local tsunami mitigation policies. It is also important in view of tsunami warning system since it can help to identify the minimum earthquake magnitude capable of triggering destructive tsunamis induced by landslides, and therefore to set up appropriate knowledge-based criteria to launch alert to the population.

  4. A shallow crustal earthquake doublet from the Trans-Mexican volcanic belt (Central Mexico)

    NASA Astrophysics Data System (ADS)

    Quintanar, L.; Rodríguez-González, M.; Campos-Enríquez, O.

    2003-04-01

    The trans-Mexican volcanic belt is an active volcanic arc related to subduction along the Middle America trench and characterized by shallow seismicity and synvolcanic to postvolcanic extensional arc-parallel faulting. The Mezquital graben is a major intra-arc basin of the central trans-Mexican volcanic belt. A doublet of moderate shallow shocks occurred in March and October 1976 in the region of this graben. These earthquakes were recorded by the Mexican National Seismological network, in particular by the Bosch-Omori seismograph (T_0 = 18 s) at the Tacubaya Observatory in Mexico City. We have carefully relocated the two main shocks and their major aftershocks by reading the original records and using a modified crustal velocity model for this region. A difference of ˜50 km is observed between the locations reported by the Mexican Seismological Service and those obtained in this study, which are additionally supported by the damage distribution of these earthquakes. A first motion analysis, based on regional and teleseismic records, defines for the March and October shocks normal fault mechanisms, characterized by E-W striking fault planes, which coincides with the orientation of the master faults of the Mezquital graben. After calculating the instrumental response, the source parameters were obtained from the Bosch-Omori seismograph records by body-wave modeling. For the March earthquake, we estimate a seismic moment of 4.5×1023 dyne-cm (equivalent to M_w=5.0) and a stress drop of 0.7 MPa assuming a circular rupture model (radius = 3 km). Given the poor quality of the Bosch-Omori record for the October earthquake, we used the comparison, between both events, of long-period (T=20 sec) teleseismic records at 2 stations to obtain its corresponding source parameters. By assuming a similar stress drop as for the March event, we obtain a M_0 of 5.6×1023 dyne-cm and M_w = 5.1 with a rupture length of 6.5 km. According to gravity data, the regional E-W faults are

  5. Multidisciplinary approach for the characterization of landslides in volcanic areas - a case study from the Palma Sola-Chiconquiaco Mountain Range, Mexico

    NASA Astrophysics Data System (ADS)

    Wilde, Martina; Rodríguez Elizarrarás, Sergio R.; Morales Barrera, Wendy V.; Schwindt, Daniel; Bücker, Matthias; Flores Orozco, Adrián; García García, Emilio; Pita de la Paz, Carlos; Terhorst, Birgit

    2017-04-01

    The Palma Sola-Chiconquiaco mountain range, situated in the State of Veracruz, Mexico, is highly susceptible to landslides, which is evidenced by the high frequency of landslide events of different sizes. The study area is located near the Gulf of Mexico coastline in the eastern sector of the Trans Mexican Volcanic Belt. There, landslide triggers are intense rainfalls related to tropical storms and hurricanes. Steeper slopes are commonly affected by rockfalls, whereas moderate slopes, covered by massive slope deposits, are affected by shallow as well as deep seated landslides. Some of the landslides in the slope deposits reach dimensions of more than 1000 m in length and depths of over 30 m. The heterogeneous parent material as well as older slide masses hamper the detailed characterization of the involved materials. Therefore, in this study, a multidisciplinary approach is applied that integrates geomorphological, geological, and geophysical data. The aim is the reconstruction of process dynamics by analyzing the geomorphological situation and subsurface conditions before and after the event. The focus lies on the identification of past landslide areas, which represent areas with high susceptibility for the reactivation of old slide masses. Furthermore, the analysis of digital terrain models, generated before the landslide event, indicate initial movements like extension cracks, which are located close to the current scarp area. In order to characterize the subsurface of slide masses geophysical investigations are applied. The geophysical survey consists of a total of nine profiles covering relevant key features of the large affected area. Along these profiles, electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) data were collected. Both, electrical and seismic images reveal a sharp contrast between relatively loose and dry material of the slide mass (high resistivities and low seismic velocities) and the former land surface that is

  6. Landslides density map of S. Miguel Island, Azores archipelago

    NASA Astrophysics Data System (ADS)

    Valadão, P.; Gaspar, J. L.; Queiroz, G.; Ferreira, T.

    The Azores archipelago is located in the Atlantic Ocean and is composed of nine volcanic islands. S. Miguel, the largest one, is formed by three active, E-W trending, trachytic central volcanoes with caldera (Sete Cidades, Fogo and Furnas). Chains of basaltic cinder cones link those major volcanic structures. An inactive trachytic central volcano (Povoação) and an old basaltic volcanic complex (Nordeste) comprise the easternmost part of the island. Since the settlement of the island early in the 15th century, several destructive landslides triggered by catastrophic rainfall episodes, earthquakes and volcanic eruptions occurred in different areas of S. Miguel. One unique event killed thousands of people in 1522. Houses and bridges were destroyed, roads were cut, communications, water and energy supply systems became frequently disrupted and areas of fertile land were often buried by mud. Based on (1) historical documents, (2) aerial photographs and (3) field observations, landslide sites were plotted on a topographic map, in order to establish a landslide density map for the island. Data obtained showed that landslide hazard is higher on (1) the main central volcanoes where the thickness of unconsolidated pyroclastic deposits is considerable high and (2) the old basaltic volcanic complex, marked by deep gullies developed on thick sequences of lava flows. In these areas, caldera walls, fault scarps, steep valley margins and sea cliffs are potentially hazardous.

  7. Uncertainties for seismic moment tensors and applications to nuclear explosions, volcanic events, and earthquakes

    NASA Astrophysics Data System (ADS)

    Tape, C.; Alvizuri, C. R.; Silwal, V.; Tape, W.

    2017-12-01

    When considered as a point source, a seismic source can be characterized in terms of its origin time, hypocenter, moment tensor, and source time function. The seismologist's task is to estimate these parameters--and their uncertainties--from three-component ground motion recorded at irregularly spaced stations. We will focus on one portion of this problem: the estimation of the moment tensor and its uncertainties. With magnitude estimated separately, we are left with five parameters describing the normalized moment tensor. A lune of normalized eigenvalue triples can be used to visualize the two parameters (lune longitude and lune latitude) describing the source type, while the conventional strike, dip, and rake angles can be used to characterize the orientation. Slight modifications of these five parameters lead to a uniform parameterization of moment tensors--uniform in the sense that equal volumes in the coordinate domain of the parameterization correspond to equal volumes of moment tensors. For a moment tensor m that we have inferred from seismic data for an earthquake, we define P(V) to be the probability that the true moment tensor for the earthquake lies in the neighborhood of m that has fractional volume V. The average value of P(V) is then a measure of our confidence in our inference of m. The calculation of P(V) requires knowing both the probability P(w) and the fractional volume V(w) of the set of moment tensors within a given angular radius w of m. We apply this approach to several different data sets, including nuclear explosions from the Nevada Test Site, volcanic events from Uturuncu (Bolivia), and earthquakes. Several challenges remain: choosing an appropriate misfit function, handling time shifts between data and synthetic waveforms, and extending the uncertainty estimation to include more source parameters (e.g., hypocenter and source time function).

  8. Polarization anisotropy for monitoring seismogenic and volcanic zones- application to Mount Fuji at the time of the 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Saade, Maria; Montagner, Jean-Paul; Araragi, Kohtaro; Roux, Philippe; Brenguier, Florent

    2017-04-01

    In active regions (seismogenic and volcanic zones), the polarization of surface waves is mainly related to seismic anisotropy. It can be derived by using seismic interferometry. We use continuous data recorded in the area around Mount Fuji, covering the year 2011 in which the Tohoku-Oki earthquake, Japan (Mw=9.0) occurred. Previously, seismic velocity measurements done using cross-correlations of seismic noise, revealed that the Tohoku-Oki earthquake also affected the velocity structure of volcanic zones such as the Mount Fuji area (Brenguier et al. 2014). In fact, seismic velocity dropped by 0.1% in the shallow depth (<10km) underneath the area of Mount Fuji due to the high sensitivity of the volcanic crust and the presence of pressurized fluids in the volcanic fissures. Results of this study show that the orientation of seismic anisotropy has significantly changed at the time of the earthquake inducing strong and rapid deviations of the horizontal polarization of surface waves. These changes might be due to a change in the alignment of cracks when subject to a co-seismic stress perturbation.

  9. Coping with volcanic hazards; a global perspective

    Tilling, R.I.

    1990-01-01

    Compared to some other natural hazards-such as floods, storms, earthquakes, landslides- volcanic hazards strike infrequently. However, in populated areas , even very small eruptions can wreak havoc and cause widespread devastation. For example, the 13 November 1985 eruption of Nevado del Ruiz in Colombia ejected only about 3 percent of the volume of ash produced during the 18 May 1980 eruption of Mount St. Helens. Yet, the mudflows triggered by this tiny eruption killed more than 25,000 people.

  10. Investigation of landslide potential parameters on Zonguldak-Ereğli Highway and adverse effects of landslides in the region.

    PubMed

    Can, Eray

    2014-04-01

    Landslides are natural phenomena in the same class of natural disasters as earthquakes, floods, hurricanes, erosion, and volcanic eruptions that adversely affect human lives and property. Owing to their widespread occurrence, landslides are easily visible and able to be partially understood by people witnessing them. Nevertheless, to comprehend the detail of their formation and determine their potential, it is necessary to undertake geodetic, geological, and geophysical measurements in regions prone to landslides. By analyzing these measurements, it is possible to better ascertain those regions predisposed to landslides and thus provide the means to prevent loss of life and property. The city of Zonguldak, situated in the Western Black Sea region of Turkey, has a high occurrence of landslides owing to its harsh topography with rugged and steep slopes and rainfall in almost every season. Furthermore, the diurnal temperature ranging up to 10 °C in all seasons, especially in winter, plays a crucial role in rock disintegration in this region. Other factors damage ground composition and trigger landslides, such as underground mining operations, road construction that collapses rocky hills using explosives, and excavation works in steep terrain for building construction. This study gives a detailed account of the causes and adverse effects of landslides and their parameters through examples of landslide occurrences in the region, together with the results and analyses of two periods of geodetic measurements conducted on the Zonguldak-Ereğli Highway in Ilıksu district.

  11. Landslide database dominated by rainfall triggered events

    NASA Astrophysics Data System (ADS)

    Devoli, G.; Strauch, W.; Álvarez, A.

    2009-04-01

    A digital landslide database has been created for Nicaragua to provide the scientific community and national authorities with a tool for landslide hazard assessment. Valuable information on landslide events has been obtained from a great variety of sources. On the basis of the data stored in the database, preliminary analyses performed at national scale aimed to characterize landslides in terms of spatial and temporal distribution, types of slope movements, triggering mechanisms, number of casualties and damage to infrastructure. A total of about 17000 events spatially distributed in mountainous and volcanic terrains have been collected in the database. The events are temporally distributed between 1826 and 2003, but a large number of the records (62% of the total number) occurred during the disastrous Hurricane Mitch in October 1998. The results showed that debris flows are the most common types of landslides recorded in the database (66% of the total amount), but other types, including rockfalls and slides, have also been identified. Rainfall, also associated with tropical cyclones, is the most frequent triggering mechanism of landslides in Nicaragua, but also seismic and volcanic activities are important triggers or, especially, the combination of one of them with rainfall. Rainfall has caused all types of failures, but debris flows and translational shallow slides are more frequent types. Earthquakes have most frequently triggered rockfalls and slides, while volcanic eruptions rockfalls and debris flows. Landslides triggered by rainfall were limited in time to the wet season that lasts from May to October and an increase in the number of events is observed during the months of September and October, which is in accord with the period of the rainy season in the Pacific and Northern and Central regions and when the country has the highest probability of being impacted by hurricanes. Both Atlantic and Pacific tropical cyclones have triggered landslides. At the

  12. Correlations of volcanic ash texture with explosion earthquakes from vulcanian eruptions at Sakurajima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Miwa, T.; Toramaru, A.; Iguchi, M.

    2009-07-01

    We compare the texture of volcanic ash with the maximum amplitude of explosion earthquakes ( Aeq) for vulcanian eruptions from Sakurajima volcano. We analyze the volcanic ash emitted by 17 vulcanian eruptions from 1974 to 1987. Using a stereoscopic microscope, we classify the glassy particles into smooth surface particles (S-type particles) and non-smooth surface particles (NS-type particles) according to their surface conditions—gloss or non-gloss appearance—as an indicator of the freshness of the particles. S-type particles are further classified into V-type particles (those including vesicles) and NV-type particles (those without vesicles) by means of examinations under a polarized microscopic of polished thin sections. Cross-correlated examinations against seismological data show that: 1) the number fraction of S-type particles (S-fraction) has a positive correlation with Aeq, 2) the number ratio of NV-type particles to V-type particles (the N/V number ratio) has a positive correlation with Aeq, and 3) for explosions accompanied with BL-type earthquake swarms, the N/V number ratio has a negative correlation with the duration of the BL-Swarms. BL-Swarms refer to the phenomenon of numerous BL-type earthquakes occurring within a few days, prior to an increase in explosive activity [Kamo, K., 1978. Some phenomena before the summit crater eruptions at Sakura-zima volcano. Bull. Volcanol. Soc. Japan., 23, 53-64]. The positive correlation between the N/V number ratio and Aeq could indicate that a large amount of separated gas from fresh magma results in a large Aeq. Plagioclase microlite textual analysis of NV-type particles from five explosive events without BL-Swarms shows that the plagioclase microlite number density (MND) and the L/ W (length/width) ratio have a positive correlation with Aeq. A comparison between textural data (MND, L/ W ratio, crystallinity) and the result of a decompression-induced crystallization experiment [Couch, S., Sparks, R

  13. Complex landslides in the Trans-Mexican Volcanic Belt - a case study in the State of Veracruz

    NASA Astrophysics Data System (ADS)

    Wilde, M.; Terhorst, B.; Schwindt, D.; Rodriguez Elizarrarás, S. R.; Morales Barrera, W. V.; Bücker, M.; Flores Orozco, A.; García García, E.; Pita de la Paz, C.

    2017-12-01

    The State of Veracruz (Mexico) is a region which is highly affected by landslides, therefore detailed studies on triggering factors and process dynamics of landslides are required. Profound insights are essential for further hazard assessments and compilation of susceptibility maps. Exemplary landslide sites were investigated in order to determine characteristic features of specific regions. In the Chiconquiaco Mountain Range numerous damaging landslide events occurred in the year of 2013 and our case study corresponds to a deep-seated landslide originating from this slide-intensive year. The main scientific aspects are placed on the reconstruction of the landslides geometry and its process dynamics. Therefore, surface and subsurface analysis form the base of a multimethodological approach. In order to perform surface analysis, aerial photographs were collected by an unmanned aerial vehicle (UAV) aiming at the generation of a 3D model with the Structure from Motion (SfM) work routine. Ground control points (GCP) were used to ensure the geometric accuracy of the model. The obtained DEM of the 2013 slide mass as well as an elevation model representing the topographic situation before the event (year 2011) were used to detect surface changes. The data enabled determination of the most affected areas as well as areas characterized by secondary movements. Furthermore, the volume of the slide mass could be calculated. Geophysical methods, as electrical resistivity tomography (ERT) as well as seismic refraction tomography (SRT), were applied for subsurface analysis. Differences in subsurface composition, respectively density, allowed for separation of the slide mass and the underlying unit. Most relevant for our studies is the detection of an earlier landslide leading to the assumption that the 2013 landslide event corresponds to a reactivation process. This multimethodological approach enables a far-reaching visualization of complex landslides and strongly supports the

  14. Alarm systems detect volcanic tremor and earthquake swarms during Redoubt eruption, 2009

    NASA Astrophysics Data System (ADS)

    Thompson, G.; West, M. E.

    2009-12-01

    We ran two alarm algorithms on real-time data from Redoubt volcano during the 2009 crisis. The first algorithm was designed to detect escalations in continuous seismicity (tremor). This is implemented within an application called IceWeb which computes reduced displacement, and produces plots of reduced displacement and spectrograms linked to the Alaska Volcano Observatory internal webpage every 10 minutes. Reduced displacement is a measure of the amplitude of volcanic tremor, and is computed by applying a geometrical spreading correction to a displacement seismogram. When the reduced displacement at multiple stations exceeds pre-defined thresholds and there has been a factor of 3 increase in reduced displacement over the previous hour, a tremor alarm is declared. The second algorithm was to designed to detect earthquake swarms. The mean and median event rates are computed every 5 minutes based on the last hour of data from a real-time event catalog. By comparing these with thresholds, three swarm alarm conditions can be declared: a new swarm, an escalation in a swarm, and the end of a swarm. The end of swarm alarm is important as it may mark a transition from swarm to continuous tremor. Alarms from both systems were dispatched using a generic alarm management system which implements a call-down list, allowing observatory scientists to be called in sequence until someone acknowledged the alarm via a confirmation web page. The results of this simple approach are encouraging. The tremor alarm algorithm detected 26 of the 27 explosive eruptions that occurred from 23 March - 4 April. The swarm alarm algorithm detected all five of the main volcanic earthquake swarm episodes which occurred during the Redoubt crisis on 26-27 February, 21-23 March, 26 March, 2-4 April and 3-7 May. The end-of-swarm alarms on 23 March and 4 April were particularly helpful as they were caused by transitions from swarm to tremor shortly preceding explosive eruptions; transitions which were

  15. Estimation of full moment tensors, including uncertainties, for earthquakes, volcanic events, and nuclear explosions

    NASA Astrophysics Data System (ADS)

    Alvizuri, Celso R.

    We present a catalog of full seismic moment tensors for 63 events from Uturuncu volcano in Bolivia. The events were recorded during 2011-2012 in the PLUTONS seismic array of 24 broadband stations. Most events had magnitudes between 0.5 and 2.0 and did not generate discernible surface waves; the largest event was Mw 2.8. For each event we computed the misfit between observed and synthetic waveforms, and we used first-motion polarity measurements to reduce the number of possible solutions. Each moment tensor solution was obtained using a grid search over the six-dimensional space of moment tensors. For each event we show the misfit function in eigenvalue space, represented by a lune. We identify three subsets of the catalog: (1) 6 isotropic events, (2) 5 tensional crack events, and (3) a swarm of 14 events southeast of the volcanic center that appear to be double couples. The occurrence of positively isotropic events is consistent with other published results from volcanic and geothermal regions. Several of these previous results, as well as our results, cannot be interpreted within the context of either an oblique opening crack or a crack-plus-double-couple model. Proper characterization of uncertainties for full moment tensors is critical for distinguishing among physical models of source processes. A seismic moment tensor is a 3x3 symmetric matrix that provides a compact representation of a seismic source. We develop an algorithm to estimate moment tensors and their uncertainties from observed seismic data. For a given event, the algorithm performs a grid search over the six-dimensional space of moment tensors by generating synthetic waveforms for each moment tensor and then evaluating a misfit function between the observed and synthetic waveforms. 'The' moment tensor M0 for the event is then the moment tensor with minimum misfit. To describe the uncertainty associated with M0, we first convert the misfit function to a probability function. The uncertainty, or

  16. Subduction of the Pacific Plate Beneath the Kamchatka: Volcanism and Tectonic Earthquakes

    NASA Astrophysics Data System (ADS)

    Gordeev, E. I.

    2008-12-01

    The results of studying subduction process of the Pacific plate beneath the Kamchatka and related processes are described. The focal mechanism solutions estimated from Centroid Moment Tensor (CMT) catalog and sequence of the largest earthquakes occurred in Kamchatka were used to asses velocity of subducted slab. The boundary of contact for subducted slab is determined at a depth of 30-70 km, and is considered as a plane at azimuth 217° and with a dip angle of 25°. The rate of subduction estimated from CMT mechanisms yields V=0.9 cm/yr for southern zone (south of Shipunsky Cape), and V=1.4 cm/yr for central zone (from Shipunsky Cape to Kronotsky Cape). The largest coupled consistent earthquakes recorded from 1737 were used for analysis. The results show, that for the southern area V=6.6 - 7.1 cm yr (two couples), and for the central part V=6.6 cm yr. The estimated value of velocity for the creep part of subducted slab is about 5 to 15 per cent of the bulk velocity. The Pacific plate subducts at a rate of 8 cm yr. Series of GPS observations conducted from 1997 up to 2007 were used to estimate the rate at which Kamchatka is deformed under the effect of the subducted slab (along-slab direction). The average values of rate and velocity variations versus the average rate were estimated response to permanent GPS station PETR. It was shown that the motion at BKI (Bering) regardless KlU (Klyuchi) is uneven: variations of velocity reach up to 30 per cent (at average running window of 1 year). There are about 28 active volcanoes in Kamchatka that provide intensive volcanic activity in this region. The volcanoes produce about 16-17% of magmatic rocks erupted by all volcanoes in the Earth. Over the past 5 years, eruptions of Sheveluch, Klyuchevskoy, Bezymianny, Karymsky, and Mutnovsky volcanoes have occurred. Although many of these volcanoes are in sparsely populated areas, they lie adjacent to the heavily North Pacific air routes between North America, Europe and Asia. The

  17. The 10 April 2014 Nicaraguan Crustal Earthquake: Evidence of Complex Deformation of the Central American Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Suárez, Gerardo; Muñoz, Angélica; Farraz, Isaac A.; Talavera, Emilio; Tenorio, Virginia; Novelo-Casanova, David A.; Sánchez, Antonio

    2016-10-01

    On 10 April 2014, an M w 6.1 earthquake struck central Nicaragua. The main event and the aftershocks were clearly recorded by the Nicaraguan national seismic network and other regional seismic stations. These crustal earthquakes were strongly felt in central Nicaragua but caused relatively little damage. This is in sharp contrast to the destructive effects of the 1972 earthquake in the capital city of Managua. The differences in damage stem from the fact that the 1972 earthquake occurred on a fault beneath the city; in contrast, the 2014 event lies offshore, under Lake Managua. The distribution of aftershocks of the 2014 event shows two clusters of seismic activity. In the northwestern part of Lake Managua, an alignment of aftershocks suggests a northwest to southeast striking fault, parallel to the volcanic arc. The source mechanism agrees with this right-lateral, strike-slip motion on a plane with the same orientation as the aftershock sequence. For an earthquake of this magnitude, seismic scaling relations between fault length and magnitude predict a sub-surface fault length of approximately 16 km. This length is in good agreement with the extent of the fault defined by the aftershock sequence. A second cluster of aftershocks beneath Apoyeque volcano occurred simultaneously, but spatially separated from the first. There is no clear alignment of the epicenters in this cluster. Nevertheless, the decay of the number of earthquakes beneath Apoyeque as a function of time shows the typical behavior of an aftershock sequence and not of a volcanic swarm. The northeast-southwest striking Tiscapa/Ciudad Jardín and Estadio faults that broke during the 1972 and 1931 Managua earthquakes are orthogonal to the fault where the 10 April earthquake occurred. These orthogonal faults in close geographic proximity show that Central Nicaragua is being deformed in a complex tectonic setting. The Nicaraguan forearc sliver, between the trench and the volcanic arc, moves to the

  18. Recent seismicity of the southwestern Ethiopian rift and implication for earthquake and volcanic risk

    NASA Astrophysics Data System (ADS)

    Ayele, Atalay

    2014-05-01

    The southwestern part of the Ethiopian rift is one of the most seismically and volcanically active tectonic units in East Africa. Notable seismic events have occurred in 2010 and 2011 in Hosanna and Yirgalem, respectively. The main shock of the Hosanna event occurred on December 19, 2010 with magnitude 5.2 mb and was located 15-20 km northwest of the town. It caused significant damage on several buildings in Hosanna and the shaking was felt from Mizan town in the south as far as Addis Ababa in the north. Damages on buildings were sever in walls facing east and west which is sub-parallel to the extension direction of the main Ethiopian rift. Patients rushed out unconsciously from hospitals in Hosanna but luckily no damage on human life was reported. It was also strongly felt in Jimma town and students from Jimma University accommodated at higher floors of the residence buildings were terrified and rushing down where it caused injuries of over 26 students during that event. The seismic activity continued for over a year. The Yirgalem earthquake occurred on March 19, 2011 with magnitude 5.1 mb close to a highly populated area near Yirgalem town and it was widely felt in the area but there was no significant damage except demolishing of loosely plastered walls. The feeling of the residents was complicated by their perception on the famous Tohuku earthquake of March 11, 2011 that occurred a week before and the associated disaster which was widely televised all over the world. Seismologists and geophysicists from Addis Ababa University had to go to the site to make presentations and make some outreach campaigns that saved thousands of residents from fleeing the area. These recent seismic activities in the highly populated main Ethiopian rift were a warning call both for the construction industry and decision makers to create awareness so as to save human life and property from eminent earthquake disasters. This recent seismic activity in southwestern Ethiopia sheds light

  19. Numerical Modeling of Earthquake-Induced Landslide Using an Improved Discontinuous Deformation Analysis Considering Dynamic Friction Degradation of Joints

    NASA Astrophysics Data System (ADS)

    Huang, Da; Song, Yixiang; Cen, Duofeng; Fu, Guoyang

    2016-12-01

    Discontinuous deformation analysis (DDA) as an efficient technique has been extensively applied in the dynamic simulation of discontinuous rock mass. In the original DDA (ODDA), the Mohr-Coulomb failure criterion is employed as the judgment principle of failure between contact blocks, and the friction coefficient is assumed to be constant in the whole calculation process. However, it has been confirmed by a host of shear tests that the dynamic friction of rock joints degrades. Therefore, the friction coefficient should be gradually reduced during the numerical simulation of an earthquake-induced rockslide. In this paper, based on the experimental results of cyclic shear tests on limestone joints, exponential regression formulas are fitted for dynamic friction degradation, which is a function of the relative velocity, the amplitude of cyclic shear displacement and the number of its cycles between blocks with an edge-to-edge contact. Then, an improved DDA (IDDA) is developed by implementing the fitting regression formulas and a modified removing technique of joint cohesion, in which the cohesion is removed once the `sliding' or `open' state between blocks appears for the first time, into the ODDA. The IDDA is first validated by comparing with the theoretical solutions of the kinematic behaviors of a sliding block on an inclined plane under dynamic loading. Then, the program is applied to model the Donghekou landslide triggered by the 2008 Wenchuan earthquake in China. The simulation results demonstrate that the dynamic friction degradation of joints has great influences on the runout and velocity of sliding mass. Moreover, the friction coefficient possesses higher impact than the cohesion of joints on the kinematic behaviors of the sliding mass.

  20. Credible occurrence probabilities for extreme geophysical events: earthquakes, volcanic eruptions, magnetic storms

    Love, Jeffrey J.

    2012-01-01

    Statistical analysis is made of rare, extreme geophysical events recorded in historical data -- counting the number of events $k$ with sizes that exceed chosen thresholds during specific durations of time $\\tau$. Under transformations that stabilize data and model-parameter variances, the most likely Poisson-event occurrence rate, $k/\\tau$, applies for frequentist inference and, also, for Bayesian inference with a Jeffreys prior that ensures posterior invariance under changes of variables. Frequentist confidence intervals and Bayesian (Jeffreys) credibility intervals are approximately the same and easy to calculate: $(1/\\tau)[(\\sqrt{k} - z/2)^{2},(\\sqrt{k} + z/2)^{2}]$, where $z$ is a parameter that specifies the width, $z=1$ ($z=2$) corresponding to $1\\sigma$, $68.3\\%$ ($2\\sigma$, $95.4\\%$). If only a few events have been observed, as is usually the case for extreme events, then these "error-bar" intervals might be considered to be relatively wide. From historical records, we estimate most likely long-term occurrence rates, 10-yr occurrence probabilities, and intervals of frequentist confidence and Bayesian credibility for large earthquakes, explosive volcanic eruptions, and magnetic storms.

  1. A Possible Explanation for the Absence of Large Tsunami Following the Earthquake of March 28, 2005 in the Northern Sumatra: No Major Submarine Landslide

    NASA Astrophysics Data System (ADS)

    Lee, S.-M.

    2005-05-01

    In just over three months, two large earthquakes (magnitudes Mw = 9.0 and 8.7), separated only by a few hundred kilometers in epicenter distance, shook the fore-arc region of the northern Sumatra. According to preliminary reports released by USGS (http://neic.usgs.gov), the seismic moment tensor solutions of the two events match quite well, suggesting that the movement of fault blocks that triggered them was similar. Yet the two earthquakes had drastically different consequence: the December 2004 earthquake triggered a catastrophic tsunami whereas the March 2005 earthquake did not. This difference raises an important question that the December 2004 tsunami was not actually triggered by the faulting itself but by submarine landslide. Earthquake-triggered submarine landslides can sometimes be overlooked as the direct cause of major tsunamis because their location often coincides with the fault rupture zones, but are known to be an important source especially along the active margins with high sedimentation rate. Scientists suspect that a similar event happened on July 17, 1998, when a magnitude 7.0 earthquake triggered by low-angle thrust fault caused a submarine slumping, which in turn generated the tsunami that devastated the coastal region in NW Papua New Guinea, killing more than 2000 human lives. If this was the case in Sumatra, it explains why a major tsunami did not occur following the March 2005 earthquake. A large amount of the sediment deposited along the continental margin by the erosion of high mountain ranges of Sumatra had already slid down the continental slope during the earthquake on December 26, 2004, and therefore not much volume of sediment was left to slide down and generate another major tsunami. The submarine topography may have also been a factor as the area around the epicenter of March 2005 earthquake has a longer extent of steep down-slope section compared to that of December 2004. In addition, the region around December 2004 earthquake has

  2. Submarine landslides

    Hampton, M.A.; Lee, H.J.; Locat, J.

    1996-01-01

    Landslides are common on inclined areas of the seafloor, particularly in environments where weak geologic materials such as rapidly deposited, finegrained sediment or fractured rock are subjected to strong environmental stresses such as earthquakes, large storm waves, and high internal pore pressures. Submarine landslides can involve huge amounts of material and can move great distances: slide volumes as large as 20,000 km3 and runout distances in excess of 140 km have been reported. They occur at locations where the downslope component of stress exceeds the resisting stress, causing movement along one or several concave to planar rupture surfaces. Some recent slides that originated nearshore and retrogressed back across the shoreline were conspicuous by their direct impact on human life and activities. Most known slides, however, occurred far from land in prehistoric time and were discovered by noting distinct to subtle characteristics, such as headwall scarps and displaced sediment or rock masses, on acoustic-reflection profiles and side-scan sonar images. Submarine landslides can be analyzed using the same mechanics principles as are used for occurrences on land. However, some loading mechanisms are unique, for example, storm waves, and some, such as earthquakes, can have greater impact. The potential for limited-deformation landslides to transform into sediment flows that can travel exceedingly long distances is related to the density of the slope-forming material and the amount of shear strength that is lost when the slope fails.

  3. Faulting within the Mount St. Helens conduit and implications for volcanic earthquakes

    Pallister, John S.; Cashman, Katharine V.; Hagstrum, Jonathan T.; Beeler, Nicholas M.; Moran, Seth C.; Denlinger, Roger P.

    2013-01-01

    The 2004–2008 eruption of Mount St. Helens produced seven dacite spines mantled by cataclastic fault rocks, comprising an outer fault core and an inner damage zone. These fault rocks provide remarkable insights into the mechanical processes that accompany extrusion of degassed magma, insights that are useful in forecasting dome-forming eruptions. The outermost part of the fault core consists of finely comminuted fault gouge that is host to 1- to 3-mm-thick layers of extremely fine-grained slickenside-bearing ultracataclasite. Interior to the fault core, there is an ∼2-m-thick damage zone composed of cataclastic breccia and sheared dacite, and interior to the damage zone, there is massive to flow-banded dacite lava of the spine interior. Structures and microtextures indicate entirely brittle deformation, including rock breakage, tensional dilation, shearing, grain flow, and microfaulting, as well as gas and fluid migration through intergranular pores and fractures in the damage zone. Slickenside lineations and consistent orientations of Riedel shears indicate upward shear of the extruding spines against adjacent conduit wall rocks.Paleomagnetic directions, demagnetization paths, oxide mineralogy, and petrology indicate that cataclasis took place within dacite in a solidified steeply dipping volcanic conduit at temperatures above 500 °C. Low water content of matrix glass is consistent with brittle behavior at these relatively high temperatures, and the presence of tridymite indicates solidification depths of <1 km. Cataclasis was coincident with the eruption’s seismogenic zone at <1.5 km.More than a million small and low-frequency “drumbeat” earthquakes with coda magnitudes (Md) <2.0 and frequencies <5 Hz occurred during the 2004–2008 eruption. Our field data provide a means with which to estimate slip-patch dimensions for shear planes and to compare these with estimates of slip patches based on seismic moments and shear moduli for dacite rock and

  4. Landslides caused by the Klamath Falls, Oregon, earthquakes of September 20, 1993

    Keefer, D.K.; Schuster, R.L.

    1993-01-01

    In the Klamath Falls area, the most numerous earthquake-induced rock falls were along the east-to southeast-facing flank of a ridge immediately south and west of Howard Bay (locality 1 on the accompanying map), 18 km east-southeast of the epicenter of the magntiude 6.0 shock at 10:45 p.m. This ridge is more than 240 m high and has slopes steeper than 45° in places. The upper part of the ridge is composed of material from basaltic lava flows, an the lower slopes are covered with colluvium and talus deposits containing abundant boulders. 

  5. Earthquake swarm in the non-volcanic area north of Harrat Lunayyir, western Saudi Arabia: observations and imaging

    NASA Astrophysics Data System (ADS)

    Youssof, M.; Mai, P. M.; Parisi, L.; Tang, Z.; Zahran, H. M.; El-Hadidy, S. Y.; Al-Raddadi, W.; Sami, M.; El-Hadidy, M. S. Y.

    2017-12-01

    We report on an unusual earthquake swarm in a non-volcanic area of western Saudi Arabia. Since March 2017, hundreds of earthquakes were recorded, reaching magnitude Ml 3.7, which occurred within a very narrowly defined rock volume. The seismicity is shallow, mostly between 4 to 8 km depths, with some events reaching as deep as 16 km. One set of events aligns into a well-defined horizontal tube of 2 km height, 1 km width, and 4-5 km E-W extent. Other event clusters exist, but are less well-defined. The focal mechanism solutions of the largest earthquakes indicate normal faulting, which agree with the regional stress field. The earthquake swarm occurs 75 km NW of Harrat Lunayyir. However, the area of interest doesn't seem to be associated with the well-known volcanic area of Harrat Lunayyir, which experienced a magmatic dike intrusion in 2009 with intense seismic activity (including a surface rupturing Mw 5.7 earthquake). Furthermore, the study area is characterized by a complex shear system, which host gold mineralization. Therefore, the exact origin of the swarm sequence is enigmatic as it's the first of its kind in this region. By using continuous seismological data recorded by the Saudi Geological Survey (SGS) that operates three permanent seismic stations and a temporary network of 11 broadband sensors, we analyze the seismic patterns in space and time. For the verified detected events, we assemble the body wave arrival times that are inverted for the velocity structures along with events hypocenters to investigate possible causes of this swarm sequence, that is, whether the activity is of tectonic- or hydro-thermal origin.

  6. New imaging of submarine landslides from the 1964 earthquake near Whittier, Alaska, and a comparison to failures in other Alaskan fjords

    Haeussler, Peter J.; Parsons, Thomas E.; Finlayson, David P.; Hart, Patrick J.; Chaytor, Jason D.; Ryan, Holly F; Lee, Homa J.; Labay, Keith A.; Peterson, Andrew; Liberty, Lee

    2014-01-01

    The 1964 Alaska M w 9.2 earthquake triggered numerous submarine slope failures in fjords of southern Alaska. These failures generated local tsunamis, such as at Whittier, where they inundated the town within 4 min of the beginning of shaking. Run-up was up to 32 m, with 13 casualties. We collected new multibeam bathymetry and high-resolution sparker seismic data in Passage Canal, and we examined bathymetry changes before and after the earthquake. The data reveal the debris flow deposit from the 1964 landslides, which covers the western 5 km of the fjord bottom. Individual blocks in the flow are up to 145-m wide and 25-m tall. Bathymetry changes show the mass transfer deposits originated from the fjord head and Whittier Creek deltas and had a volume of about 42 million m3. The 1964 deposit has an average thickness of ∼5.4 m. Beyond the debris flow, the failures likely deposited a ∼4.6-m thick megaturbidite in a distal basin. We have studied the 1964 submarine landslides in three fjords. All involved failure of the fjord-head delta. All failures eroded basin-floor sediments and incorporated them as they travelled. All the failures deposited blocks, but their size and travel distances varied greatly. We find a correlation between maximum block size and maximum tsunami run-up regardless of the volume of the slides. Lastly, the fjord’s margins were influenced by increased supply of glacial sediments during the little ice age, which along with a long interseismic interval (∼900 years) may have caused the 1964 earthquake to produce particularly numerous and large submarine landslides.

  7. Fault reactivation due to the M7.6 Nicoya earthquake at the Turrialba-Irazú volcanic complex, Costa Rica: Effects of dynamic stress triggering

    NASA Astrophysics Data System (ADS)

    Lupi, M.; Fuchs, Florian; Pacheco, Javier F.

    2014-06-01

    The M7.6 Nicoya earthquake struck at the interface between the Cocos plate and the Caribbean plate on 5 September 2012 inducing a ground acceleration of 0.5 m s-2 at the Irazú-Turrialba volcanic complex. We use data from six seismic stations deployed around and atop the Irazú-Turrialba volcanic complex to show the increase of local seismic activity after the M7.6 Nicoya earthquake. The response consists in more than 300 locatable earthquakes occurring in swarm sequences along a fault system that intersects the Irazú-Turrialba volcanic complex. In addition, we point out that major aftershocks are followed by increases of seismic activity in the same region. The weak static stress variation imposed by the main slip of the Nicoya earthquake at the Irazú-Turrialba volcanic complex suggests a dynamic triggering mechanism. We expand this concept suggesting that this behavior may be similar to the one observed in the Chilean and Japanese volcanic arcs during the M8.8 2010 Maule, Chile, and M9.0 2011 Tohoku, Japan, earthquakes. Finally, we highlight that the combined action of dynamic stress and short-lived coseismic relaxation may trigger seismic activity in geological systems in near-critical conditions.

  8. Innovative Techniques for Teaching about Landslides and Triggered Landslide Events

    NASA Astrophysics Data System (ADS)

    Taylor, F. E.; Malamud, B. D.

    2014-12-01

    When we think of a landslide (mass wasting), both the public and scientists often envisage an individual movement of earth material down a slope. Yet, landslides often occur not as individuals, but as parts of a triggered landslide event. This is where a trigger (e.g., an earthquake or heavy rainfall) results in up to tens of thousands of landslides in a region in the minutes to days after the trigger. In this paper, we will present ideas for innovative demonstrations, teaching practicals and projects, ranging from low-cost low-tech to more advanced digital methods, to communicate the ideas of landslides and triggered landslide events to the public and students. This paper is aimed at those in secondary school/university education and the public sector looking for examples to interest and inform their respective audiences about landslides, triggered landslide events, and the importance and implications of considering landslides not just as individuals, but as populations.

  9. Earthquakes

    MedlinePlus

    ... Search Term(s): Main Content Home Be Informed Earthquakes Earthquakes An earthquake is the sudden, rapid shaking of the earth, ... by the breaking and shifting of underground rock. Earthquakes can cause buildings to collapse and cause heavy ...

  10. Imaging the Eastern Trans-Mexican Volcanic Belt and the Veracruz Basin with Ambient Seismic noise and Earthquake Body Waves

    NASA Astrophysics Data System (ADS)

    Castillo, J.; Clayton, R. W.

    2017-12-01

    The Trans-Mexican Volcanic Belt (TMVB) is a prominent and enigmatic feature of the subduction system in Mexico. Its volcanic style diversity and oblique orientation to the trench are explained by the large along-strike variations in the subduction parameters of the Rivera and Cocos plates. However, the abrupt termination of the TMVB on its eastern end with the Pico de Orizaba volcano is puzzling as the current slab model suggests that the transition of the Cocos flat-slab geometry to normal subduction is smooth through this region. There is evidence that suggests that a tear in the slab might be developing, but it is unclear how this feature can support the unusually large topographic gradient that connects the volcanic high peaks with the Veracruz basin just south of the volcanic front. To provide further insight into the transition anatomy of this portion of the slab, and its relation with surface topography, we present a detailed and unified model of the structure of the crust and uppermost mantle built from fundamental-mode Rayleigh and Love surface waves, and high-quality arrival-time data of regional and teleseismic earthquakes. The anisotropic behavior of the subsurface of this region and its relation with present and past flow of material is also quantified and integrated into the model to explain the tectonic evolution of this area.

  11. Combined effects of tectonic and landslide-generated Tsunami Runup at Seward, Alaska during the Mw 9.2 1964 earthquake

    Suleimani, E.; Nicolsky, D.J.; Haeussler, Peter J.; Hansen, R.

    2011-01-01

    We apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of Resurrection Bay and the town of Seward by the 1964 Alaska tsunami. Seward was hit by both tectonic and landslide-generated tsunami waves during the Mw 9.2 1964 mega thrust earthquake. The earthquake triggered a series of submarine mass failures around the fjord, which resulted in land sliding of part of the coastline into the water, along with the loss of the port facilities. These submarine mass failures generated local waves in the bay within 5 min of the beginning of strong ground motion. Recent studies estimate the total volume of underwater slide material that moved in Resurrection Bay to be about 211 million m3 (Haeussler et al. in Submarine mass movements and their consequences, pp 269-278, 2007). The first tectonic tsunami wave arrived in Resurrection Bay about 30 min after the main shock and was about the same height as the local landslide-generated waves. Our previous numerical study, which focused only on the local land slide generated waves in Resurrection Bay, demonstrated that they were produced by a number of different slope failures, and estimated relative contributions of different submarine slide complexes into tsunami amplitudes (Suleimani et al. in Pure Appl Geophys 166:131-152, 2009). This work extends the previous study by calculating tsunami inundation in Resurrection Bay caused by the combined impact of landslide-generated waves and the tectonic tsunami, and comparing the composite inundation area with observations. To simulate landslide tsunami runup in Seward, we use a viscous slide model of Jiang and LeBlond (J Phys Oceanogr 24(3):559-572, 1994) coupled with nonlinear shallow water equations. The input data set includes a high resolution multibeam bathymetry and LIDAR topography grid of Resurrection Bay, and an initial thickness of slide material based on pre- and post-earthquake bathymetry difference maps. For

  12. Tharsis Landslide

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The landslide in the VIS image occurs in the Tharsis region of Mars, just north of Hebes Chasma. The volcanic flows forming the lower surface in the image have a platy texture. The landslide is younger than the volcanic flow, as the landslide sits on top of the flow surface.

    Image information: VIS instrument. Latitude 5, Longitude 282.4 East (77.6 West). 19 meter/pixel resolution.

    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.

    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.

  13. Volcanic soils and landslides: a case study of the island of Ischia (southern Italy) and its relationship with other Campania events

    NASA Astrophysics Data System (ADS)

    Vingiani, S.; Mele, G.; De Mascellis, R.; Terribile, F.; Basile, A.

    2015-06-01

    An integrated investigation was carried out on the volcanic soils involved in the landslide phenomena that occurred in 2006 at Mt. Vezzi on the island of Ischia (southern Italy). Chemical (soil pH, organic carbon content, exchangeable cations and cation exchange capacity, electrical conductivity, Na adsorption ratio and Al, Fe and Si forms), physical (particle and pore size distribution, pore structure), hydrological (soil water retention, saturated and unsaturated hydraulic conductivity), mineralogical and micromorphological analyses were carried out for three soil profiles selected in two of the main head scarps. The studied soils showed a substantial abrupt discontinuity in all the studied properties at the interface with a buried fine ash layer (namely, the 2C horizon), that was only marginally involved in the sliding surface of the landslide phenomena. When compared to the overlying horizons, 2C showed (i) fine grey ash that is almost pumice free, with the silt content increasing by 20 %; (ii) ks values 1 order of magnitude lower; (iii) a pore distribution concentrated into small (15-30 μm modal class) pores characterised by a very low percolation threshold (approximately 15-25 μm); (iv) the presence of expandable clay minerals; and (v) increasing Na content in the exchange complex. Most of these properties indicated that 2C was a lower permeability horizon compared to the overlying ones. Nevertheless, it was possible to assume this interface to be an impeding layer to vertical water fluxes only by the identification of a thin (6.5 mm) finely stratified ash layer, on top of 2C, and of the hydromorphic features (e.g. Fe / Mn concretions) within and on top of the layer. Although Mt. Vezzi's soil environment has many properties in common with those of other Campania debris-mudflows (e.g. high gradient, north-facing slope, similar forestry, and volcanic origin of the parent material), the results of this study suggest a more complex relationship between soil

  14. Surficial Seismology: Landslides, Glaciers, and Volcanoes in the Pacific Northwest through a Seismic Lens

    NASA Astrophysics Data System (ADS)

    Allstadt, Kate

    The following work is focused on the use of both traditional and novel seismological tools, combined with concepts from other disciplines, to investigate shallow seismic sources and hazards. The study area is the dynamic landscape of the Pacific Northwest and its wide-ranging earthquake, landslide, glacier, and volcano-related hazards. The first chapter focuses on landsliding triggered by earthquakes, with a shallow crustal earthquake in Seattle as a case study. The study demonstrates that utilizing broadband synthetic seismograms and rigorously incorporating 3D basin amplification, 1D site effects, and fault directivity, allows for a more complete assessment of regional seismically induced landslide hazard. The study shows that the hazard is severe for Seattle, and provides a framework for future probabilistic maps and near real-time hazard assessment. The second chapter focuses on landslides that generate seismic waves and how these signals can be harnessed to better understand landslide dynamics. This is demonstrated using two contrasting Pacific Northwest landslides. The 2010 Mount Meager, BC, landslide generated strong long period waves. New full waveform inversion methods reveal the time history of forces the landslide exerted on the earth that is used to quantify event dynamics. Despite having a similar volume (˜107 m3), The 2009 Nile Valley, WA, landslide did not generate observable long period motions because of its smaller accelerations, but pulses of higher frequency waves were valuable in piecing together the complex sequence of events. The final chapter details the difficulties of monitoring glacier-clad volcanoes. The focus is on small, repeating, low-frequency earthquakes at Mount Rainier that resemble volcanic earthquakes. However, based on this investigation, they are actually glacial in origin: most likely stick-slip sliding of glaciers triggered by snow loading. Identification of the source offers a view of basal glacier processes, discriminates

  15. Short-term volcano-tectonic earthquake forecasts based on a moving mean recurrence time algorithm: the El Hierro seismo-volcanic crisis experience

    NASA Astrophysics Data System (ADS)

    García, Alicia; De la Cruz-Reyna, Servando; Marrero, José M.; Ortiz, Ramón

    2016-05-01

    Under certain conditions, volcano-tectonic (VT) earthquakes may pose significant hazards to people living in or near active volcanic regions, especially on volcanic islands; however, hazard arising from VT activity caused by localized volcanic sources is rarely addressed in the literature. The evolution of VT earthquakes resulting from a magmatic intrusion shows some orderly behaviour that may allow the occurrence and magnitude of major events to be forecast. Thus governmental decision makers can be supplied with warnings of the increased probability of larger-magnitude earthquakes on the short-term timescale. We present here a methodology for forecasting the occurrence of large-magnitude VT events during volcanic crises; it is based on a mean recurrence time (MRT) algorithm that translates the Gutenberg-Richter distribution parameter fluctuations into time windows of increased probability of a major VT earthquake. The MRT forecasting algorithm was developed after observing a repetitive pattern in the seismic swarm episodes occurring between July and November 2011 at El Hierro (Canary Islands). From then on, this methodology has been applied to the consecutive seismic crises registered at El Hierro, achieving a high success rate in the real-time forecasting, within 10-day time windows, of volcano-tectonic earthquakes.

  16. Seismic tomography of Basse-Terre volcanic island, Guadeloupe, Lesser Antilles, using earthquake travel times and noise correlations

    NASA Astrophysics Data System (ADS)

    Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Massin, Frédérick; Stehly, Laurent

    2015-04-01

    We image the volcanic island of Basse-Terre, Guadeloupe, Lesser Antilles, using both earthquake travel times and noise correlations. (1) A new earthquake catalog was recently compiled for the Lesser Antilles by the CDSA/OVSG/IPGP (Massin et al., EGU General Assembly 2014) and allows us to perform classical travel time tomography to obtain smooth 3D body wave velocity models. The geometrical configuration of the volcanic arc controls the resolution of the model in our zone of interest. (2) Surface wave tomography using noise correlations was successfully applied to volcanoes (Brenguier et al., Geophys. Res. Lett. 2007). We use seismic noise recorded at 16 broad-band stations and 9 short-period stations from Basse-Terre over a period of six years (2007-2012). For each station pair, we extract a dispersion curve from the noise correlation to get surface wave velocity models. The inversion of the dispersion curves produces a 3D S-wave velocity model of the island. The spatial distribution of seismic stations accross the island is highly heterogeneous, leading to higher resolution near the dome of the Soufrière of Guadeloupe volcano. Resulting velocity models are compared with densities obtained by 3D inversion of gravimetric data (Barnoud et al., AGU Fall Meeting 2013). Further work should include simultaneous inversion of seismic and gravimetric datasets to overcome resolution limitations.

  17. Earthquake mechanism and seafloor deformation for tsunami generation

    Geist, Eric L.; Oglesby, David D.; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

    2014-01-01

    Tsunamis are generated in the ocean by rapidly displacing the entire water column over a significant area. The potential energy resulting from this disturbance is balanced with the kinetic energy of the waves during propagation. Only a handful of submarine geologic phenomena can generate tsunamis: large-magnitude earthquakes, large landslides, and volcanic processes. Asteroid and subaerial landslide impacts can generate tsunami waves from above the water. Earthquakes are by far the most common generator of tsunamis. Generally, earthquakes greater than magnitude (M) 6.5–7 can generate tsunamis if they occur beneath an ocean and if they result in predominantly vertical displacement. One of the greatest uncertainties in both deterministic and probabilistic hazard assessments of tsunamis is computing seafloor deformation for earthquakes of a given magnitude.

  18. Landslide seismic magnitude

    NASA Astrophysics Data System (ADS)

    Lin, C. H.; Jan, J. C.; Pu, H. C.; Tu, Y.; Chen, C. C.; Wu, Y. M.

    2015-11-01

    Landslides have become one of the most deadly natural disasters on earth, not only due to a significant increase in extreme climate change caused by global warming, but also rapid economic development in topographic relief areas. How to detect landslides using a real-time system has become an important question for reducing possible landslide impacts on human society. However, traditional detection of landslides, either through direct surveys in the field or remote sensing images obtained via aircraft or satellites, is highly time consuming. Here we analyze very long period seismic signals (20-50 s) generated by large landslides such as Typhoon Morakot, which passed though Taiwan in August 2009. In addition to successfully locating 109 large landslides, we define landslide seismic magnitude based on an empirical formula: Lm = log ⁡ (A) + 0.55 log ⁡ (Δ) + 2.44, where A is the maximum displacement (μm) recorded at one seismic station and Δ is its distance (km) from the landslide. We conclude that both the location and seismic magnitude of large landslides can be rapidly estimated from broadband seismic networks for both academic and applied purposes, similar to earthquake monitoring. We suggest a real-time algorithm be set up for routine monitoring of landslides in places where they pose a frequent threat.

  19. Evaluation of the evolving stress field of the Yellowstone volcanic plateau, 1988 to 2010, from earthquake first-motion inversions

    NASA Astrophysics Data System (ADS)

    Russo, E.; Waite, G. P.; Tibaldi, A.

    2017-03-01

    Although the last rhyolite eruption occurred around 70 ka ago, the silicic Yellowstone volcanic field is still considered active due to high hydrothermal and seismic activity and possible recent magma intrusions. Geodetic measurements document complex deformation patterns in crustal strain and seismic activity likewise reveal spatial and temporal variations in the stress field. We use earthquake data recorded between 1988 and 2010 to investigate these variations and their possible causes in more detail. Earthquake relocations and a set of 369 well-constrained, double-couple, focal mechanism solutions were computed. Events were grouped according to location and time to investigate trends in faulting. The majority of the events have normal-faulting solutions, subordinate strike-slip kinematics, and very rarely, reverse motions. The dominant direction of extension throughout the 0.64 Ma Yellowstone caldera is nearly ENE, consistent with the perpendicular direction of alignments of volcanic vents within the caldera, but our study also reveals spatial and temporal variations. Stress-field solutions for different areas and time periods were calculated from earthquake focal mechanism inversion. A well-resolved rotation of σ3 was found, from NNE-SSW near the Hebgen Lake fault zone, to ENE-WSW near Norris Junction. In particular, the σ3 direction changed throughout the years around Norris Geyser Basin, from being ENE-WSW, as calculated in the study by Waite and Smith (2004), to NNE-SSW, while the other σ3 directions are mostly unchanged over time. The presence of ;chocolate tablet; structures, with two sets of nearly perpendicular normal faults, was identified in many stages of the deformation history both in the Norris Geyser Basin area and inside the caldera.

  20. Earthquakes and Volcanic Processes at San Miguel Volcano, El Salvador, Determined from a Small, Temporary Seismic Network

    NASA Astrophysics Data System (ADS)

    Hernandez, S.; Schiek, C. G.; Zeiler, C. P.; Velasco, A. A.; Hurtado, J. M.

    2008-12-01

    The San Miguel volcano lies within the Central American volcanic chain in eastern El Salvador. The volcano has experienced at least 29 eruptions with Volcano Explosivity Index (VEI) of 2. Since 1970, however, eruptions have decreased in intensity to an average of VEI 1, with the most recent eruption occurring in 2002. Eruptions at San Miguel volcano consist mostly of central vent and phreatic eruptions. A critical challenge related to the explosive nature of this volcano is to understand the relationships between precursory surface deformation, earthquake activity, and volcanic activity. In this project, we seek to determine sub-surface structures within and near the volcano, relate the local deformation to these structures, and better understand the hazard that the volcano presents in the region. To accomplish these goals, we deployed a six station, broadband seismic network around San Miguel volcano in collaboration with researchers from Servicio Nacional de Estudios Territoriales (SNET). This network operated continuously from 23 March 2007 to 15 January 2008 and had a high data recovery rate. The data were processed to determine earthquake locations, magnitudes, and, for some of the larger events, focal mechanisms. We obtained high precision locations using a double-difference approach and identified at least 25 events near the volcano. Ongoing analysis will seek to identify earthquake types (e.g., long period, tectonic, and hybrid events) that occurred in the vicinity of San Miguel volcano. These results will be combined with radar interferometric measurements of surface deformation in order to determine the relationship between surface and subsurface processes at the volcano.

  1. Earthquakes

    MedlinePlus

    An earthquake happens when two blocks of the earth suddenly slip past one another. Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a populated area, it may cause ...

  2. Landslide inventories: The essential part of seismic landslide hazard analyses

    Harp, E.L.; Keefer, D.K.; Sato, H.P.; Yagi, H.

    2011-01-01

    A detailed and accurate landslide inventory is an essential part of seismic landslide hazard analysis. An ideal inventory would cover the entire area affected by an earthquake and include all of the landslides that are possible to detect down to sizes of 1-5. m in length. The landslides must also be located accurately and mapped as polygons depicting their true shapes. Such mapped landslide distributions can then be used to perform seismic landslide hazard analysis and other quantitative analyses. Detailed inventory maps of landslide triggered by earthquakes began in the early 1960s with the use of aerial photography. In recent years, advances in technology have resulted in the accessibility of satellite imagery with sufficiently high resolution to identify and map all but the smallest of landslides triggered by a seismic event. With this ability to view any area of the globe, we can acquire imagery for any earthquake that triggers significant numbers of landslides. However, a common problem of incomplete coverage of the full distributions of landslides has emerged along with the advent of high resolution satellite imagery. ?? 2010.

  3. On the occurrence of fatal landslides in 2008

    NASA Astrophysics Data System (ADS)

    Petley, D.

    2009-04-01

    This paper represents the latest in an annual review of fatal landslide events worldwide, based upon the Durham Fatal Landslide Database. Landslide events were inevitably dominated by the occurrence of the 12th May Wenchuan Earthquake in Sichuan Province of China, which triggered very extensive landsliding. Whilst it will be very difficult to estimate the true impact of this event in terms of landslides, the Chinese authorities estimate that about 29,000 people were killed by landslides, with several thousand more losing their lives whilst trapped in rubble due to the inability of rescuers to pass through landslide affected areas. Considerable work is needed to understand the reasons for the intensity of the landslide processes. Elsewhere the number of fatal landslides recorded totalled 405 worldwide. These caused 3526 fatalities, giving a total for the year of about 32,526 people. To put this into context, according to the CRED EM-DAT database the recorded number of fatalities from volcanic eruptions in the period 2000 to 2008 inclusive is 221! The distribution of fatal landslides followed the familiar patterns observed in previous years, with distinct clusters in Central China, along the southern edge of the Himalayas, in the Caribbean, in Central America, western S. America, along the western edge of the Philippine Sea plate and in Indonesia, plus a scattering elsewhere. The temporal distribution shows strong seasonality, with the peak occurring during the northern hemisphere summer. Unusually however, the peak month was September (usually it is in July), and there were large numbers of landslide events right through to November. The November landslide clusters occurred in SE. Asia and in Central / S. America, reflecting very heavy rains in these regions at that time. The reasons for this are not clear at present, although may be linked to weakening La Nina conditions that have prevailed through much of the year. An analysis is made of the relationship between

  4. Complex Non-volcanic Tremor in Guerrero Mexico Triggered by the 2010 Mw 8.8 Chilean Earthquake

    NASA Astrophysics Data System (ADS)

    Zigone, D.; Campillo, M.; Husker, A. L.; Kostoglodov, V.; Payero, J. S.; Frank, W.; Shapiro, N. M.; Voisin, C.; Cougoulat, G.; Cotte, N.

    2010-12-01

    In this study we analyze the tremors triggered in Guerrero region (Mexico) by the 2010 magnitude 8.8 Chilean Earthquake using mini-seismic array data from the French-Mexican G-GAP project and broadband data from the Servicio Sismologico Nacional of Mexico. The strong dynamic shaking by the earthquake produced the first observed triggered non-volcanic tremors (NVT) in Mexico so far with at least 3 different types of tremors at different time scales. There was a slow slip event (SSE) occurring at the time of the earthquake, which may have increased the probability of tremor triggering in the region. The first type of observed triggered tremors occurred during the S waves, Love waves and Rayleigh waves as already reported in other subductions zones and continental faults (Miyazawa and Mori, 2005, 2006; Rubinstein et al., 2007; Gomberg et al., 2008; Peng et al, 2009…). The greatest amount of energy and duration accompanies the long-period Rayleigh waves, with smaller bursts during the S and Love waves. For this particular tremor we observed the dispersion of Rayleigh waves in the envelopes of triggered tremors, which indicates a very strong modulation of the source by the passing surface wave. An unexpected short-term tremor occurred approximately one hour later of the arrival of the surface waves on the coastal stations. The NVT has only been previously observed at distances > 100 km inland. It also has a shorter frequency range (3-6 Hz) than other NVT (1-10 Hz) observed in the region. Finally, we observed a significant increase of so-called ambient tremor activity with higher intensity than all triggered NVT during the days after the earthquake. This study adds new types of tremors to the lexicon of triggered NVT observed in the world.

  5. Earthquakes.

    ERIC Educational Resources Information Center

    Pakiser, Louis C.

    One of a series of general interest publications on science topics, the booklet provides those interested in earthquakes with an introduction to the subject. Following a section presenting an historical look at the world's major earthquakes, the booklet discusses earthquake-prone geographic areas, the nature and workings of earthquakes, earthquake…

  6. Earthquakes.

    ERIC Educational Resources Information Center

    Walter, Edward J.

    1977-01-01

    Presents an analysis of the causes of earthquakes. Topics discussed include (1) geological and seismological factors that determine the effect of a particular earthquake on a given structure; (2) description of some large earthquakes such as the San Francisco quake; and (3) prediction of earthquakes. (HM)

  7. Earthquakes and submarine volcanism in the Northeast Pacific: Exploration in the time domain based on 21-years of hydroacoustic monitoring

    NASA Astrophysics Data System (ADS)

    Hammond, S. R.; Dziak, R. P.; Fox, C. G.

    2012-12-01

    Monitoring of regional seismic activity in the Northeast Pacific has been accomplished for the past 21 years using US Navy's Sound Surveillance System (SOSUS) hydrophone arrays. Seafloor seismic activity in this region occurs along the spreading center and transform boundaries between the Juan de Fuca, Pacific and North American plates. During the time span, from 1991 through 2011, nearly 50,000 earthquakes were detected and located. The majority of these events were associated with these tectonic boundaries but sections of several plate boundaries were largely aseismic during the this time span. While most of the earthquakes were associated with geological structures revealed in bathymetric maps of the region, there were also less easily explained intraplate events including a swarm of events within the interior of the southern portion of the Juan de Fuca plate. The location and sequential timing of events on portions of the plate boundaries also suggests ordered patterns of stress release. Among the most scientifically significant outcomes of acoustic monitoring was the discovery that deep seafloor magmatic activity can be accompanied by intense (> 1000 events/day) earthquake swarms. The first swarm detected by SOSUS, in 1993, was confirmed to have been associated with an extrusive volcanic eruption which occurred along a segment of the Juan de Fuca spreading center. Notably, this was the first deep spreading center eruption detected, located, and studied while it was active. Subsequently, two more swarms were confirmed to have been associated with volcanic eruptions, one on the Gorda spreading center in 1996 and the other at Axial volcano in 1998. One characteristic of these swarm events is migration of their earthquake locations 10s of km along the ridge axis tracking the movement of magma down-rift. The most rapid magma propagation events have been shown to be associated with seafloor eruptions and dramatic, transient changes in hydrothermal circulation as

  8. Venus - Landslide in Navka Region

    1996-03-14

    NASA Magellan spacecraft observed remnant landslide deposits apparently resulting from the collapse of volcanic structures. This radar image is centered in the southwestern Navka Region of Venus. http://photojournal.jpl.nasa.gov/catalog/PIA00262

  9. Increased degassing from the Southern Central American Volcanic Arc in response to crustal stress change following the 2012 Nicoya earthquake?

    NASA Astrophysics Data System (ADS)

    de Moor, M. J.; Kern, C.; Fischer, T. P.; Avard, G.; Aiuppa, A.; Protti, M.; Muller, C.; Alvarez, J.; Saballos, J. A.; Galle, B.

    2016-12-01

    The aim of this work is to provide an updated assessment of SO2 and CO2 fluxes from the Southern Central America Volcanic Arc (SCAVA) for the period 2015-2016. We present over 300 new ground-based remote sensing sulfur dioxide flux measurements (DOAS traverses) conducted at 10 volcanoes in Costa Rica and Nicaragua, representing the most comprehensive assessment of volcanic gas flux at SCAVA to date. The data were filtered to exclude measurements directly associated with eruptive activity. The SO2 flux from this 500km section of arc is thus conservatively estimated at 4622 ± 1586 tons/day (unfiltered average of the data yields 6114 ± 1956 tons/day SO2). Our best estimate is about double that of any previous estimations (data from 1972-2013). We attribute this increase in part to our more complete assessment of the arc, as previous studies considered fluxes from only 5 to 7 of the SCAVA volcanoes. Additionally,a greater number of SCAVA volcanoes have had eruptions in 2015-2016 than in any two-year period since 1980. A possible explanation for increased degassing and volcanic activity is a change in crustal stress regime following the 2012 Nicoya earthquake (Mw = 7.8). GPS data show that the SCAVA has experienced a dramatic change from compression to extension, potentially opening conduits for volatiles and magmas to rise from the mantle and lower crustal regions. The dominant contributors to volcanic degassing at SCAVA are Masaya and Turrialba volcanoes, which show average passive degassing SO2 fluxes of 1984 ± 890 T/d and 1672 ± 925 T/d respectively during 2015-2016. High-quality MultiGAS time series datasets for both of these volcanoes provide robust measurements of CO2/SO2 values associated with SO2 flux measurement at these volcanoes. Based on these data we estimate the CO2 flux from Masaya at 5487 ± 1800 T/d and from Turrialba at 4873 ± 2053 T/d. Combining our arc SO2 flux data with gas composition data for the other volcanoes as well as estimations of

  10. Lithospheric flexure under the Hawaiian volcanic load: Internal stresses and a broken plate revealed by earthquakes

    NASA Astrophysics Data System (ADS)

    Klein, Fred W.

    2016-04-01

    Several lines of earthquake evidence indicate that the lithospheric plate is broken under the load of the island of Hawai`i, where the geometry of the lithosphere is circular with a central depression. The plate bends concave downward surrounding a stress-free hole, rather than bending concave upward as with past assumptions. Earthquake focal mechanisms show that the center of load stress and the weak hole is between the summits of Mauna Loa and Mauna Kea where the load is greatest. The earthquake gap at 21 km depth coincides with the predicted neutral plane of flexure where horizontal stress changes sign. Focal mechanism P axes below the neutral plane display a striking radial pattern pointing to the stress center. Earthquakes above the neutral plane in the north part of the island have opposite stress patterns; T axes tend to be radial. The M6.2 Honomu and M6.7 Kiholo main shocks (both at 39 km depth) are below the neutral plane and show radial compression, and the M6.0 Kiholo aftershock above the neutral plane has tangential compression. Earthquakes deeper than 20 km define a donut of seismicity around the stress center where flexural bending is a maximum. The hole is interpreted as the soft center where the lithospheric plate is broken. Kilauea's deep conduit is seismically active because it is in the ring of maximum bending. A simplified two-dimensional stress model for a bending slab with a load at one end yields stress orientations that agree with earthquake stress axes and radial P axes below the neutral plane. A previous inversion of deep Hawaiian focal mechanisms found a circular solution around the stress center that agrees with the model. For horizontal faults, the shear stress within the bending slab matches the slip in the deep Kilauea seismic zone and enhances outward slip of active flanks.

  11. Detection of the 2015 Gorkha earthquake-induced landslide surface deformation in Kathmandu using InSAR images from PALSAR-2 data

    NASA Astrophysics Data System (ADS)

    Sato, Hiroshi P.; Une, Hiroshi

    2016-03-01

    Previous studies reported that the 2015 Gorkha earthquake (Mw 7.8), which occurred in Nepal, triggered landslides in mountainous areas. In Kathmandu, earthquake-induced land subsidence was identified by interpreting local phase changes in interferograms produced from Advanced Land Observing Satellite-2/Phased Array type L-band Synthetic Aperture Radar-2 data. However, the associated ground deformation was not discussed in detail. We studied line-of-sight (LoS) changes from InSAR images in the SE area of Tribhuvan International Airport, Kathmandu. To obtain the change in LoS caused only by local, short-wavelength surface deformation, we subtracted the change in LoS attributed to coseismic deformation from the original change in LoS. The resulting change in LoS showed that the river terrace was driven to the bottom of the river valley. We also studied the changes in LoS in both ascending and descending InSAR images of the area along the Bishnumati River and performed 2.5D analysis. Removing the effect of coseismic deformation revealed east-west and up-down components of local surface deformation, indicating that the river terrace deformed eastward and subsided on the western riverbank of the river. On the east riverbank, the river terrace deformed westward and subsided. However, in the southern part of the river basin, the river terrace deformed westward and was uplifted. The deformation data and field survey results indicate that local surface deformation in these two areas was not caused by land subsidence but by a landslide (specifically, lateral spread).

  12. Waveform classification of volcanic low-frequency earthquake swarms and its implication at Soufrière Hills Volcano, Montserrat

    NASA Astrophysics Data System (ADS)

    Green, David N.; Neuberg, Jürgen

    2006-05-01

    Low-frequency volcanic earthquakes are indicators of magma transport and activity within shallow conduit systems. At a number of volcanoes, these events exhibit a high degree of waveform similarity providing a criterion for classification. Using cross-correlation techniques to quantify the degree of similarity, we develop a method to sort events into families containing comparable waveforms. Events within a family have been triggered within one small source volume from which the seismic wave has then travelled along an identical path to the receiver. This method was applied to a series of 16 low-frequency earthquake swarms, well correlated with cyclic deformation recorded by tiltmeters, at Soufrière Hills Volcano, Montserrat, in June 1997. Nine waveform groups were identified containing more than 45 events each. The families are repeated across swarms with only small changes in waveform, indicating that the seismic source location is stable with time. The low-frequency seismic swarms begin prior to the point at which inflation starts to decelerate, suggesting that the seismicity indicates or even initiates a depressurisation process. A major dome collapse occurred within the time window considered, removing the top 100 m of the dome. This event caused activity within some families to pause for several cycles before reappearing. This shows that the collapse did not permanently disrupt the source mechanism or the path of the seismic waves.

  13. Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management (G-EVER) project and a next-generation real-time volcano hazard assessment system

    NASA Astrophysics Data System (ADS)

    Takarada, S.

    2012-12-01

    The first Workshop of Asia-Pacific Region Global Earthquake and Volcanic Eruption Risk Management (G-EVER1) was held in Tsukuba, Ibaraki Prefecture, Japan from February 23 to 24, 2012. The workshop focused on the formulation of strategies to reduce the risks of disasters worldwide caused by the occurrence of earthquakes, tsunamis, and volcanic eruptions. More than 150 participants attended the workshop. During the workshop, the G-EVER1 accord was approved by the participants. The Accord consists of 10 recommendations like enhancing collaboration, sharing of resources, and making information about the risks of earthquakes and volcanic eruptions freely available and understandable. The G-EVER Hub website (http://g-ever.org) was established to promote the exchange of information and knowledge among the Asia-Pacific countries. Several G-EVER Working Groups and Task Forces were proposed. One of the working groups was tasked to make the next-generation real-time volcano hazard assessment system. The next-generation volcano hazard assessment system is useful for volcanic eruption prediction, risk assessment, and evacuation at various eruption stages. The assessment system is planned to be developed based on volcanic eruption scenario datasets, volcanic eruption database, and numerical simulations. Defining volcanic eruption scenarios based on precursor phenomena leading up to major eruptions of active volcanoes is quite important for the future prediction of volcanic eruptions. Compiling volcanic eruption scenarios after a major eruption is also important. A high quality volcanic eruption database, which contains compilations of eruption dates, volumes, and styles, is important for the next-generation volcano hazard assessment system. The volcanic eruption database is developed based on past eruption results, which only represent a subset of possible future scenarios. Hence, different distributions from the previous deposits are mainly observed due to the differences in

  14. A Bootstrap-Based Probabilistic Optimization Method to Explore and Efficiently Converge in Solution Spaces of Earthquake Source Parameter Estimation Problems: Application to Volcanic and Tectonic Earthquakes

    NASA Astrophysics Data System (ADS)

    Dahm, T.; Heimann, S.; Isken, M.; Vasyura-Bathke, H.; Kühn, D.; Sudhaus, H.; Kriegerowski, M.; Daout, S.; Steinberg, A.; Cesca, S.

    2017-12-01

    Seismic source and moment tensor waveform inversion is often ill-posed or non-unique if station coverage is poor or signals are weak. Therefore, the interpretation of moment tensors can become difficult, if not the full model space is explored, including all its trade-offs and uncertainties. This is especially true for non-double couple components of weak or shallow earthquakes, as for instance found in volcanic, geothermal or mining environments.We developed a bootstrap-based probabilistic optimization scheme (Grond), which is based on pre-calculated Greens function full waveform databases (e.g. fomosto tool, doi.org/10.5880/GFZ.2.1.2017.001). Grond is able to efficiently explore the full model space, the trade-offs and the uncertainties of source parameters. The program is highly flexible with respect to the adaption to specific problems, the design of objective functions, and the diversity of empirical datasets.It uses an integrated, robust waveform data processing based on a newly developed Python toolbox for seismology (Pyrocko, see Heimann et al., 2017, http://doi.org/10.5880/GFZ.2.1.2017.001), and allows for visual inspection of many aspects of the optimization problem. Grond has been applied to the CMT moment tensor inversion using W-phases, to nuclear explosions in Korea, to meteorite atmospheric explosions, to volcano-tectonic events during caldera collapse and to intra-plate volcanic and tectonic crustal events.Grond can be used to optimize simultaneously seismological waveforms, amplitude spectra and static displacements of geodetic data as InSAR and GPS (e.g. KITE, Isken et al., 2017, http://doi.org/10.5880/GFZ.2.1.2017.002). We present examples of Grond optimizations to demonstrate the advantage of a full exploration of source parameter uncertainties for interpretation.

  15. Landslide-dammed lake at Tangjiashan, Sichuan province, China (triggered by the Wenchuan Earthquake, May 12, 2008): Risk assessment, mitigation strategy, and lessons learned

    Cui, P.; Dang, C.; Zhuang, J.; You, Y.; Chen, X.; Scott, K.M.

    2012-01-01

    Landslides and rock avalanches triggered by the 2008 Wenchuan Earthquake produced 257 landslide dams, mainly situated along the eastern boundary of the Qinghai-Tibet Plateau where rivers descend approximately 3,000 m into the Sichuan Basin. The largest of these dams blocked the Tongkou River (a tributary of the Fujiang River) at Tangjiashan. The blockage, consisting of 2. 04 ?? 10 7 m 3 of landslide debris, impounded a lake with a projected maximum volume of 3. 15 ?? 10 8 m 3, potentially inundating 8. 92 km 2 of terrain. Its creation during the rainy season and the possibility of an uncontrolled release posed a serious, impending threat to at least 1. 3 million people downstream that could add substantially to the total of 69,200 individuals directly killed by the earthquake. Risk assessment of the blockage indicated that it was unlikely to collapse suddenly, and that eventual overtopping could be mitigated by notching the structure in order to create an engineered breach and achieve safe drainage of the lake. In addition to the installation of monitoring and warning instrumentation, for emergency planning we estimated several outburst scenarios equivalent to 20, 25, 33, and 50% of the dam failing suddenly, creating, respectively, 3. 35, 3. 84, 4. 22, and 4. 65 km 2 of flooded area, and overbank water depths of 4. 6, 5. 1, 5. 7, and 6. 2 m, respectively, in Mianyang, the second largest city in Sichuan Province, 48 km downstream from the blockage. Based on these scenarios, recommendations and plans for excavating a sluiceway, draining the lake, and downstream evacuation were proposed and later were implemented successfully, with the blockage breached by overtopping on June 10, less than a month after dam emplacement. The peak discharge of the release only slightly exceeded the flood of record at Mianyang City. No lives were lost, and significant property damage was avoided. Post-breaching evaluation reveals how future similar mitigation can be improved. Although

  16. Lithospheric flexure under the Hawaiian volcanic load: Internal stresses and a broken plate revealed by earthquakes

    Klein, Fred W.

    2016-01-01

    Several lines of earthquake evidence indicate that the lithospheric plate is broken under the load of the island of Hawai`i, where the geometry of the lithosphere is circular with a central depression. The plate bends concave downward surrounding a stress-free hole, rather than bending concave upward as with past assumptions. Earthquake focal mechanisms show that the center of load stress and the weak hole is between the summits of Mauna Loa and Mauna Kea where the load is greatest. The earthquake gap at 21 km depth coincides with the predicted neutral plane of flexure where horizontal stress changes sign. Focal mechanism P axes below the neutral plane display a striking radial pattern pointing to the stress center. Earthquakes above the neutral plane in the north part of the island have opposite stress patterns; T axes tend to be radial. The M6.2 Honomu and M6.7 Kiholo main shocks (both at 39 km depth) are below the neutral plane and show radial compression, and the M6.0 Kiholo aftershock above the neutral plane has tangential compression. Earthquakes deeper than 20 km define a donut of seismicity around the stress center where flexural bending is a maximum. The hole is interpreted as the soft center where the lithospheric plate is broken. Kilauea's deep conduit is seismically active because it is in the ring of maximum bending. A simplified two-dimensional stress model for a bending slab with a load at one end yields stress orientations that agree with earthquake stress axes and radial P axes below the neutral plane. A previous inversion of deep Hawaiian focal mechanisms found a circular solution around the stress center that agrees with the model. For horizontal faults, the shear stress within the bending slab matches the slip in the deep Kilauea seismic zone and enhances outward slip of active flanks.

  17. Perception of flood and landslide risk in Italy: a preliminary analysis

    NASA Astrophysics Data System (ADS)

    Salvati, P.; Bianchi, C.; Fiorucci, F.; Giostrella, P.; Marchesini, I.; Guzzetti, F.

    2014-05-01

    Inundations and landslides are widespread phenomena in Italy, where they cause severe damage and pose a threat to the population. Little is known on the perception of the population of landslides and floods. This is surprising, as an accurate perception is important for the successful implementation of many risk reduction or adaptation strategies. In an attempt to fill this gap, we have conducted two national surveys to measure the perception of landslide and flood risk of the population of Italy. The surveys were executed in 2012 and 2013, performing for each survey approximately 3100 computer assisted telephone interviews. The samples of the interviewees were statistically representative for a national scale quantitative assessment. The interviewees were asked questions designed to obtain information on their: (i) perception of natural, environmental, and technological risks, (ii) direct experience or general knowledge on the occurrence of landslides and floods in their municipality, (iii) perception of the possible threat posed by landslides and floods to their safety, (iv) general knowledge on the number of victims caused by landslides or floods, and on (v) the factors that they considered important to control landslide and flood risks in Italy. The surveys revealed that the population of Italy fears technological risks more than natural risks. Of the natural risks, earthquakes were considered more dangerous than floods, landslides, and volcanic eruptions. Examination of the temporal and geographical distribution of the responses revealed that the occurrence of recent damaging events influenced risk perception locally, and that the perception persisted longer for earthquakes and decreased more rapidly for landslides and floods. We justify the differentiation with the diverse consequences of the risks. The interviewees considered inappropriate land management the main cause of landslide and flood risk, followed by illegal construction, abandonment of the

  18. The Springdale, Utah, landslide: An extraordinary event

    Jibson, R.W.; Harp, E.L.

    1996-01-01

    The most dramatic geologic effect of the M-5.7 St. George, Utah earthquake of 2 September 1992 was the triggering of the 14,000,000-m3 Springdale, Utah landslide. The roughly 10 m of landslide movement destroyed three houses, threatened several condominiums, disrupted utility lines, and temporarily closed the southwest entrance to Zion National Park. The seismic triggering of this landslide is puzzling because its distance from the earthquake epicenter, 44 km, is much greater than the farthest distance (18 km) at which similar landslides have been triggered in worldwide earthquakes of the same magnitude. Other Colorado Plateau earthquakes also have produced landslides far beyond worldwide distance limits, which suggests that regional variations in ground-shaking attenuation may require different landslide-triggering distance limits for different seismotectonic regions. Slope stability analysis and historical records of landslide movement suggest that the Springdale landslide was only slightly above limit-equilibrium conditions at the time of the earthquake. Dynamic stability analysis using Newmark's permanent-displacement method indicates coseismic landslide displacement of only 1-8 cm; this rather modest displacement probably induced enough deformation in the montmorillonitic clays along the failure surface to reduce shear strength and destabilize the slide, which continued to move for several hours after the earthquake.

  19. Investigation of giant mass movements in the Lesser Caucasus and assessment of the spatial relationship between landslides and major fault zones and volcanoes

    NASA Astrophysics Data System (ADS)

    Ofélia Matossian, Alice; Mreyen, Anne-Sophie; Karakhanian, Arkady; Havenith, Hans-Balder

    2017-04-01

    Two landslides of assumed seismic origin in the vicinity of Garni, Armenia, were investigated during a geophysical field campaign in September 2016. On the basis of geophysical prospecting (microseismic ambient noise measurements, i.e. H/V method), the thickness of the landslide deposits has been estimated and a trigger scenario model was developed. The original trigger of those landslides is not known - but one major reactivation by an earthquake in 1679 has been proved (see below). Additionally, the spatial distribution of landslides was analysed with respect to the location of major fault zones and volcanic areas. For that, a spatial analysis with GIS has been carried out on the basis of two landslide catalogues. The catalogue that was generated during this work covers the areas of including the Pambak-Sevan-Syunik and the Garni Faults as well as several volcanic areas. These NW-SE faults are mainly marked dextral strike-slip movements locally combined with reverse mechanisms. Along these fault zones strong historical earthquakes occurred, as for example one major event in 1139 (M 7.5 - 7.7). The 1679 Garni earthquake caused widespread destruction and also reactivated landslides located near the Garni Fault, including the two investigated landslides. According to historical sources, the event reached a magnitude of M=5.5-7 with an intensity between VIII and X. The volcanic areas on the other hand include the NNW-SSE-oriented Ghegham and the NW-SE Vardeniss ridges. Some of the ridges' volcanoes erupted during the Holocene, i.e. 2090 ± 70 BP for the Ghegham ridge. Nowadays, more than 80% of Armenia is covered by Quaternary volcanic formations or friable deposits which are favourable to the formation of landslides. Nevertheless, our first analysis showed that the faults have a stronger influence on landslide distribution than the volcanoes. This is also due to the indirect fact that many volcanic areas are marked by more gentle slopes than the valleys hosting the

  20. California's Vulnerability to Volcanic Hazards: What's at Risk?

    NASA Astrophysics Data System (ADS)

    Mangan, M.; Wood, N. J.; Dinitz, L.

    2015-12-01

    California is a leader in comprehensive planning for devastating earthquakes, landslides, floods, and tsunamis. Far less attention, however, has focused on the potentially devastating impact of volcanic eruptions, despite the fact that they occur in the State about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have occurred in the past 1,000 years—most recently in northern California (Lassen Peak 1914 to 1917)—and future volcanic eruptions are inevitable. The likelihood of renewed volcanism in California is about one in a few hundred to one in a few thousand annually. Eight young volcanoes, ranked as Moderate to Very High Threat [1] are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— causing earthquakes, toxic gas emissions, hydrothermal activity, and (or) ground deformation. Understanding the hazards and identifying what is at risk are the first steps in building community resilience to volcanic disasters. This study, prepared in collaboration with the State of California Governor's Office of Emergency Management and the California Geological Survey, provides a broad perspective on the State's exposure to volcano hazards by integrating mapped volcano hazard zones with geospatial data on at-risk populations, infrastructure, and resources. The study reveals that ~ 16 million acres fall within California's volcano hazard zones, along with ~ 190 thousand permanent and 22 million transitory populations. Additionally, far-field disruption to key water delivery systems, agriculture, utilities, and air traffic is likely. Further site- and sector-specific analyses will lead to improved hazard mitigation efforts and more effective disaster response and recovery. [1] "Volcanic Threat and Monitoring Capabilities

  1. Megathrust Earthquake Swarms Contemporaneous to Slow Slip and Non-Volcanic Tremor in Southern Mexico, Detected and Analyzed through a Template Matching Approach

    NASA Astrophysics Data System (ADS)

    Holtkamp, S.; Brudzinski, M. R.; Cabral-Cano, E.; Arciniega-Ceballos, A.

    2012-12-01

    An outstanding question in geophysics is the degree to which the newly discovered types of slow fault slip are related to their destructive cousin - the earthquake. Here, we utilize a local network along the Oaxacan segment of the Middle American subduction zone to investigate the potential relationship between slow slip, non-volcanic tremor (NVT), and earthquakes along the subduction megathrust. We have developed a multi-station "template matching" waveform cross correlation technique which is able to detect and locate events several orders of magnitude smaller than would be possible using more traditional techniques. Also, our template matching procedure is capable of consistently locate events which occur during periods of increased background activity (e.g., during productive NVT, loud cultural noise, or after larger earthquakes) because the multi-station detector is finely tuned to events with similar hypocentral location and focal mechanism. The local network in the Oaxaca region allows us to focus on documented megathrust earthquake swarms, which we focus on because slow slip is hypothesized to be the cause for earthquake swarms in some tectonic environments. We identify a productive earthquake swarm in July 2006 (~600 similar earthquakes detected), which occurred during a week-long episode of productive tremor and slow slip. Families of events in this sequence were also active during larger and longer slow slip events, which provides a potential link between slow slip in the transition zone and earthquakes at the downdip end of the seismogenic portion of the megathrust. Because template matching techniques only detect similar signals, detected waveforms can be stacked together to produce higher signal to noise ratios or cross correlated against each other to produce precise relative phase arrival times. We are using the refined signals to look for evidence of expansion or propagation of hypocenters during these earthquake swarms, which could be used as a

  2. Landslides of Palestinian Region

    NASA Astrophysics Data System (ADS)

    Alwahsh, H.

    2013-12-01

    Natural disasters are extreme sudden events caused by environmental and natural actors that take away the lives of many thousands of people each year and damage large amount of properties. They strike anywhere on earth, often without any warning. A risk maps of natural disaster are very useful to identify the places that might be adversely affected in the event of natural disaster. The earthquakes are one of natural disaster that have the greatest hazards and will cause loss of life and properties due to damaging the structures of building, dams, bridges. In addition, it will affect local geology and soil conditions. The site effects play an important role in earthquake risk because of its amplification or damping simulation. Another parameter in developing risk map is landslide, which is also one of the most important topics in site effect hazards. Palestine region has been suffering landslide hazards because of the topographical and geological conditions of this region. Most Palestine consists of mountainous area, which has great steep slopes and the type of soil is mainly grayish to yellowish silty clay (Marl Soil). Due to the above mentioned factors many landslides have been occurred from Negev south to the northern borders of Palestine. An example of huge and destruction landslide in a Palestine authority is the landslide in the White Mountain area in the city of Nablus, which occurred in 1997. The geotechnical and geophysical investigation as well as slope stability analysis should be considered in making landslide maps that are necessary to develop risk levels of the natural disaster. Landslides occurred in slopes that are created naturally or by human beings. Failure of soil mass occurs, and hence landslide of soil mass happen due to sliding of soil mass along a plane or curved surface. In general, the slopes become unstable when the shear stresses (driving force) generated in the soil mass exceed the available shearing resistance on the rupture surface

  3. Venus - Landslide Deposits

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Magellan spacecraft has observed remnant landslide deposits apparently resulting from the collapse of volcanic structures. This image, centered at 45.2 degrees south latitude, 201.4 degrees east longitude, shows a collapse deposit 70 kilometers (43 miles) across. The bright, highly textured deposit near the center of the image probably consists of huge blocks of fractured volcanic rock, many as large as several hundred meters across. A remnant of the volcano itself, about 20 kilometers (12.4 miles) across, is seen at the center of the image. The distorted radar appearance of the volcano is a result of extremely steep slopes on the 'scars' from which the landslide material originated. A field of numerous small volcanic domes can be seen in the northern half of the image. The bright irregular lineaments trending to the north-northwest are ridges caused by regional tectonic deformation of the upper layers of the Venusian crust.

  4. The Hungtsaiping landslide:A kinematic model based on morphology

    NASA Astrophysics Data System (ADS)

    Huang, W.-K.; Chu, H.-K.; Lo, C.-M.; Lin, M.-L.

    2012-04-01

    A large and deep-seated landslide at Hungtsaiping was triggered by the 7.3 magnitude 1999 Chi-Chi earthquake. Extensive site investigations of the landslide were conducted including field reconnaissance, geophysical exploration, borehole logs, and laboratory experiments. Thick colluvium was found around the landslide area and indicated the occurrence of a large ancient landslide. This study presents the catastrophic landslide event which occurred during the Chi-Chi earthquake. The mechanism of the 1999 landslide which cannot be revealed by the underground exploration data alone, is clarified. This research include investigations of the landslide kinematic process and the deposition geometry. A 3D discrete element method (program), PFC3D, was used to model the kinematic process that led to the landslide. The proposed procedure enables a rational and efficient way to simulate the landslide dynamic process. Key word: Hungtsaiping catastrophic landslide, kinematic process, deposition geometry, discrete element method

  5. Volcanic Eruption Forecasts From Accelerating Rates of Drumbeat Long-Period Earthquakes

    NASA Astrophysics Data System (ADS)

    Bell, Andrew F.; Naylor, Mark; Hernandez, Stephen; Main, Ian G.; Gaunt, H. Elizabeth; Mothes, Patricia; Ruiz, Mario

    2018-02-01

    Accelerating rates of quasiperiodic "drumbeat" long-period earthquakes (LPs) are commonly reported before eruptions at andesite and dacite volcanoes, and promise insights into the nature of fundamental preeruptive processes and improved eruption forecasts. Here we apply a new Bayesian Markov chain Monte Carlo gamma point process methodology to investigate an exceptionally well-developed sequence of drumbeat LPs preceding a recent large vulcanian explosion at Tungurahua volcano, Ecuador. For more than 24 hr, LP rates increased according to the inverse power law trend predicted by material failure theory, and with a retrospectively forecast failure time that agrees with the eruption onset within error. LPs resulted from repeated activation of a single characteristic source driven by accelerating loading, rather than a distributed failure process, showing that similar precursory trends can emerge from quite different underlying physics. Nevertheless, such sequences have clear potential for improving forecasts of eruptions at Tungurahua and analogous volcanoes.

  6. The 3D Elevation Program—Landslide recognition, hazard assessment, and mitigation support

    Lukas, Vicki; Carswell, Jr., William J.

    2017-01-27

    The U.S. Geological Survey (USGS) Landslide Hazards Program conducts landslide hazard assessments, pursues landslide investigations and forecasts, provides technical assistance to respond to landslide emergencies, and engages in outreach. All of these activities benefit from the availability of high-resolution, three-dimensional (3D) elevation information in the form of light detection and ranging (lidar) data and interferometric synthetic aperture radar (IfSAR) data. Research on landslide processes addresses critical questions of where and when landslides are likely to occur as well as their size, speed, and effects. This understanding informs the development of methods and tools for hazard assessment and situational awareness used to guide efforts to avoid or mitigate landslide impacts. Such research is essential for the USGS to provide improved information on landslide potential associated with severe storms, earthquakes, volcanic activity, coastal wave erosion, and wildfire burn areas.Decisionmakers in government and the private sector increasingly depend on information the USGS provides before, during, and following disasters so that communities can live, work, travel, and build safely. The USGS 3D Elevation Program (3DEP) provides the programmatic infrastructure to generate and supply lidar-derived superior terrain data to address landslide applications and a wide range of other urgent needs nationwide. By providing data to users, 3DEP reduces users’ costs and risks and allows them to concentrate on their mission objectives. 3DEP includes (1) data acquisition partnerships that leverage funding, (2) contracts with experienced private mapping firms, (3) technical expertise, lidar data standards, and specifications, and (4) most important, public access to high-quality 3D elevation data.

  7. A methodology to track temporal dynamics and rainfall thresholds of landslide processes in the East African Rift

    NASA Astrophysics Data System (ADS)

    Monsieurs, Elise; Jacobs, Liesbet; Kervyn, François; Kirschbaum, Dalia; d'Oreye, Nicolas; Derauw, Dominique; Kervyn, Matthieu; Nobile, Adriano; Trefois, Philippe; Dewitte, Olivier

    2015-04-01

    The East African rift valley is a major tectonic feature that shapes Central Africa and defines linear-shaped lowlands between highland ranges due to the action of geologic faults associated to earthquakes and volcanism. The region of interest, covering the Virunga Volcanic Province in eastern DRC, western Rwanda and Burundi, and southwest Uganda, is threatened by a rare combination of several types of geohazards, while it is also one of the most densely populated region of Africa. These geohazards can globally be classified as seismic, volcanic and landslide hazards. Landslides, include a wide range of ground movements, such as rock falls, deep failure of slopes and shallow debris flows. Landslides are possibly the most important geohazard in terms of recurring impact on the populations, causing fatalities every year and resulting in structural and functional damage to infrastructure and private properties, as well as serious disruptions of the organization of societies. Many landslides are observed each year in the whole region, and their occurrence is clearly linked to complex topographic, lithologic and vegetation signatures coupled with heavy rainfall events, which is the main triggering factor. The source mechanisms underlying landslide triggering and dynamics in the region of interest are still poorly understood, even though in recent years, some progress has been made towards appropriate data collection. Taking into account difficulties of field accessibility, we present a methodology to study landslide processes by multi-scale and multi-sensor remote sensing data from very high to low resolution (Pléiades, TRMM, CosmoSkyMed, Sentinel). The research will address the evolution over time of such data combined with other earth observations (seismic ground based networks, catalogues, rain gauge networks, GPS surveying, field observations) to detect and study landslide occurrence, dynamics and evolution. This research aims to get insights into the rainfall

  8. Interactive Teaching about Landslides and Triggered Landslide Events

    NASA Astrophysics Data System (ADS)

    Taylor, Faith E.; Malamud, Bruce D.

    2015-04-01

    When we think of a landslide (mass wasting), both the public and scientists often envisage an individual movement of earth material down a slope. Yet, landslides often occur not as individuals, but as parts of a triggered landslide event. This is where a trigger (e.g., an earthquake or heavy rainfall) results in up to tens of thousands of landslides in a region in the minutes to days after the trigger. The sum of the impacts of these landslides may be greater than individual parts. This interactive Prezi poster will present ideas for innovative demonstrations, teaching practicals and projects, ranging from low-cost low-tech to more advanced digital methods, to communicate the ideas of landslides and triggered landslide events to the public and students. We will give live hands-on demonstrations and welcome discussions with other scientists to share ideas and best practices. This paper is aimed at those in secondary school/university education and the public sector looking for examples to interest and inform their respective audiences about landslides, triggered landslide events, and the importance and implications of considering landslides not just as individuals, but as populations.

  9. 2015 Volcanic Tsunami Earthquake near Torishima Island: Array analysis of ocean bottom pressure gauge records

    NASA Astrophysics Data System (ADS)

    Fukao, Y.; Sugioka, H.; Ito, A.; Shiobara, H.; Sandanbata, O.; Watada, S.; Satake, K.

    2016-12-01

    An array of ocean bottom pressure gauges was deployed off east of Aogashima island of the Izu-Bonin arc from May 2014 to May 2015. The array consists of 10 ocean bottom pressure gauges using ParoScientific quartz resonators which can measure absolute water pressure at 7000m depth with nano-resolution. The array configures equilateral triangles with minimum and maximum lengths of 10 and 30km. This array recorded seismic and tsunami waves from the CLVD-type earthquake (M5.7) of May 02, 2015, that occurred near Torishima Island 100 km distant from the array. Comparison with records of ordinary thrust earthquakes with similar magnitudes at similar distances indicates that this event generated anomalously large tsunamis relative to seismic waves. We made an array analysis for the phase speed, propagating azimuth and travel time of tsunami wave in a frequency range 1-10 mHz, where the dispersion effect is significant. The results show excellent agreements with the frequency-dependent ray-tracing calculations. The tsunami trace apparently starts with positive onset (pressure increase) and reaches a maximum amplitude of about 200Pa (≈2cm in tsunami height). A closer inspection, however, shows a preceding negative small pulse (Fig. 1), suggesting that the seafloor deformation at the tsunami source consists of a central large uplift and a peripheral small depression. This mode of deformation is qualitatively consistent with a finite CLVD source uniformly shortened laterally and uniformly stretched vertically without volume change. The detection of weak initial motions is indebted to the array deployment of sensitive pressure gauges far away from coastal regions. The bandpass-filtered waveform is drastically different between the lower and higher frequency ranges. The waveform is single-peaked in the lower frequency range (<5 mHz) but is ringing in the higher frequency range (>5 mHz), corresponding to the tsunami spectrum that consists of the broad primary peak around 3.5 m

  10. Estimation of full moment tensors, including uncertainties, for earthquakes, volcanic events, and nuclear explosions

    NASA Astrophysics Data System (ADS)

    Alvizuri, Celso; Silwal, Vipul; Krischer, Lion; Tape, Carl

    2017-04-01

    A seismic moment tensor is a 3 × 3 symmetric matrix that provides a compact representation of seismic events within Earth's crust. We develop an algorithm to estimate moment tensors and their uncertainties from observed seismic data. For a given event, the algorithm performs a grid search over the six-dimensional space of moment tensors by generating synthetic waveforms at each grid point and then evaluating a misfit function between the observed and synthetic waveforms. 'The' moment tensor M for the event is then the moment tensor with minimum misfit. To describe the uncertainty associated with M, we first convert the misfit function to a probability function. The uncertainty, or rather the confidence, is then given by the 'confidence curve' P(V ), where P(V ) is the probability that the true moment tensor for the event lies within the neighborhood of M that has fractional volume V . The area under the confidence curve provides a single, abbreviated 'confidence parameter' for M. We apply the method to data from events in different regions and tectonic settings: small (Mw < 2.5) events at Uturuncu volcano in Bolivia, moderate (Mw > 4) earthquakes in the southern Alaska subduction zone, and natural and man-made events at the Nevada Test Site. Moment tensor uncertainties allow us to better discriminate among moment tensor source types and to assign physical processes to the events.

  11. Landslides - Cause and effect

    Radbruch-Hall, D. H.; Varnes, D.J.

    1976-01-01

    Landslides can cause seismic disturbances; landslides can also result from seismic disturbances, and earthquake-induced slides have caused loss of life in many countries. Slides can cause disastrous flooding, particularly when landslide dams across streams are breached, and flooding may trigger slides. Slope movement in general is a major process of the geologic environment that places constraints on engineering development. In order to understand and foresee both the causes and effects of slope movement, studies must be made on a regional scale, at individual sites, and in the laboratory. Areal studies - some embracing entire countries - have shown that certain geologic conditions on slopes facilitate landsliding; these conditions include intensely sheared rocks; poorly consolidated, fine-grained clastic rocks; hard fractured rocks underlain by less resistant rocks; or loose accumulations of fine-grained surface debris. Field investigations as well as mathematical- and physical-model studies are increasing our understanding of the mechanism of slope movement in fractured rock, and assist in arriving at practical solutions to landslide problems related to all kinds of land development for human use. Progressive failure of slopes has been studied in both soil and rock mechanics. New procedures have been developed to evaluate earthquake response of embankments and slopes. The finite element method of analysis is being extensively used in the calculation of slope stability in rock broken by joints, faults, and other discontinuities. ?? 1976 International Association of Engineering Geology.

  12. Combining heuristic and statistical techniques in landslide hazard assessments

    NASA Astrophysics Data System (ADS)

    Cepeda, Jose; Schwendtner, Barbara; Quan, Byron; Nadim, Farrokh; Diaz, Manuel; Molina, Giovanni

    2014-05-01

    As a contribution to the Global Assessment Report 2013 - GAR2013, coordinated by the United Nations International Strategy for Disaster Reduction - UNISDR, a drill-down exercise for landslide hazard assessment was carried out by entering the results of both heuristic and statistical techniques into a new but simple combination rule. The data available for this evaluation included landslide inventories, both historical and event-based. In addition to the application of a heuristic method used in the previous editions of GAR, the availability of inventories motivated the use of statistical methods. The heuristic technique is largely based on the Mora & Vahrson method, which estimates hazard as the product of susceptibility and triggering factors, where classes are weighted based on expert judgment and experience. Two statistical methods were also applied: the landslide index method, which estimates weights of the classes for the susceptibility and triggering factors based on the evidence provided by the density of landslides in each class of the factors; and the weights of evidence method, which extends the previous technique to include both positive and negative evidence of landslide occurrence in the estimation of weights for the classes. One key aspect during the hazard evaluation was the decision on the methodology to be chosen for the final assessment. Instead of opting for a single methodology, it was decided to combine the results of the three implemented techniques using a combination rule based on a normalization of the results of each method. The hazard evaluation was performed for both earthquake- and rainfall-induced landslides. The country chosen for the drill-down exercise was El Salvador. The results indicate that highest hazard levels are concentrated along the central volcanic chain and at the centre of the northern mountains.

  13. Earthquake!

    ERIC Educational Resources Information Center

    Hernandez, Hildo

    2000-01-01

    Examines the types of damage experienced by California State University at Northridge during the 1994 earthquake and what lessons were learned in handling this emergency are discussed. The problem of loose asbestos is addressed. (GR)

  14. Using earthquake-triggered landslides as a hillslope-scale shear strength test: Insights into rock strength properties at geomorphically relevant spatial scales in high-relief, tectonically active settings

    NASA Astrophysics Data System (ADS)

    Gallen, Sean; Clark, Marin; Godt, Jonathan; Lowe, Katherine

    2016-04-01

    The material strength of rock is known to be a fundamental property in setting landscape form and geomorphic process rates as it acts to modulate feedbacks between earth surface processes, tectonics, and climate. Despite the long recognition of its importance in landscape evolution, a quantitative understanding of the role of rock strength in affecting geomorphic processes lags our knowledge of the influence of tectonics and climate. This gap stems largely from the fact that it remains challenging to quantify rock strength at the hillslope scale. Rock strength is strongly scale dependent because the number, size, spacing, and aperture of fractures sets the upper limit on rock strength, making it difficult to extrapolate laboratory measurements to landscape-scale interpretations. Here we present a method to determine near-surface rock strength at the hillslope-scale, relying on earthquake-triggered landslides as a regional-scale "shear strength" test. We define near-surface strength as the average strength of rock sample by the landslides, which is typically < 10 m. Based on a Newmark sliding block model, which approximates slope stability during an earthquake assuming a material with frictional and cohesive strength, we developed a coseismic landslide model that is capable of reproducing statistical characteristics of the distribution of earthquake-triggered landslides. We present results from two well-documented case-studies of earthquakes that caused widespread mass-wasting; the 2008 Mw 7.9 Wenchuan Earthquake, Sichuan Province, China and the 1994 Mw. 6.8 Northridge Earthquake, CA, USA. We show how this model can be used to determine near-surface rock strength and reproduce mapped landslide patterns provided the spatial distribution of local hillslope gradient, earthquake peak ground acceleration (PGA), and coseismic landsliding are well constrained. Results suggest that near-surface rock strength in these tectonically active settings is much lower than that

  15. Three-dimensional seismic structure and moment tensors of non-double-couple earthquakes at the Hengill-Grensdalur volcanic complex, Iceland

    Miller, A.D.; Julian, B.R.; Foulger, G.R.

    1998-01-01

    The volcanic and geothermal areas of Iceland are rich sources of non-double-couple (non-DC) earthquakes. A state-of-the-art digital seismometer network deployed at the Hengill-Grensdalur volcanic complex in 1991 recorded 4000 small earthquakes. We used the best recorded of these to determine 3-D VP and VP/VS structure tomographically and accurate earthquake moment tensors. The VP field is dominated by high seismic wave speed bodies interpreted as solidified intrusions. A widespread negative (-4 per cent) VP/VS anomaly in the upper 4 km correlates with the geothermal field, but is too strong to be caused solely by the effect of temperature upon liquid water or the presence of vapour, and requires in addition mineralogical or lithological differences between the geothermal reservoir and its surroundings. These may be caused by geothermal alteration. Well-constrained moment tensors were obtained for 70 of the best-recorded events by applying linear programming methods to P- and S-wave polarities and amplitude ratios. About 25 per cent of the mechanisms are, within observational error, consistent with DC mechanisms consistent with shear faulting. The other 75 per cent have significantly non-DC mechanisms. Many have substantial explosive components, one has a substantial implosive component, and the deviatoric component of many is strongly non-DC. Many of the non-DC mechanisms are consistent, within observational error, with simultaneous tensile and shear faulting. However, the mechanisms occupy a continuum in source-type parameter space and probably at least one additional source process is occurring. This may be fluid flow into newly formed cracks, causing partial compensation of the volumetric component. Studying non-shear earthquakes such as these has great potential for improving our understanding of geothermal processes and earthquake source processes in general.

  16. Landslides in the New Madrid seismic zone

    SciT

    Jibson, R.W.; Keefer, D.K.

    1985-01-01

    During the New Madrid earthquakes of 1811-12, bluffs bordering the Mississippi alluvial plain in the epicentral region underwent large-scale landsliding. Between Cairo, Illinois and Memphis, Tennessee, the authors mapped 221 large landslides of three types: (1) old, eroded, coherent block slides and slumps; (2) old earth flows; and (3) young, fresh slumps that occur only along near-river bluffs and are the only landslides present along such bluffs. Historical accounts and field evidence indicate that most or all old coherent slides and earth flows date to the 1811-12 earthquakes and that the only currently active, large-scale landsliding in the area occursmore » along bluffs bordering the river. Analysis of old coherent slides and earth flows indicates that landslide distribution is most strongly affected by slope height, but that proximity to the hypocenters of the 1811-12 earthquakes also has a significant effect. Slope-stability analyses of an old coherent slide and an earth flow selected as representative of the principal kinds of landslides present indicate that both were stable in aseismic conditions even when water tables were at highest possible levels. However, a dynamic Newmark displacement analysis shows that ground shaking such as that in 1811-12 would cause large displacements leading to catastrophic failure in both slides. These results indicate that in large earthquakes landsliding in much of the study are is likely. Moderate earthquakes may also trigger landslides at some locations.« less

  17. Determination of source parameters of the 2017 Mount Agung volcanic earthquake from moment-tensor inversion method using local broadband seismic waveforms

    NASA Astrophysics Data System (ADS)

    Madlazim; Prastowo, T.; Supardiyono; Hardy, T.

    2018-03-01

    Monitoring of volcanoes has been an important issue for many purposes, particularly hazard mitigation. With regard to this, the aims of the present work are to estimate and analyse source parameters of a volcanic earthquake driven by recent magmatic events of Mount Agung in Bali island that occurred on September 28, 2017. The broadband seismogram data consisting of 3 local component waveforms were recorded by the IA network of 5 seismic stations: SRBI, DNP, BYJI, JAGI, and TWSI (managed by BMKG). These land-based observatories covered a full 4-quadrant region surrounding the epicenter. The methods used in the present study were seismic moment-tensor inversions, where the data were all analyzed to extract the parameters, namely moment magnitude, type of a volcanic earthquake indicated by percentages of seismic components: compensated linear vector dipole (CLVD), isotropic (ISO), double-couple (DC), and source depth. The results are given in the forms of variance reduction of 65%, a magnitude of M W 3.6, a CLVD of 40%, an ISO of 33%, a DC of 27% and a centroid-depth of 9.7 km. These suggest that the unusual earthquake was dominated by a vertical CLVD component, implying the dominance of uplift motion of magmatic fluid flow inside the volcano.

  18. Soft-sediment deformation in New Zealand: Structures resulting from the 2010/11 Christchurch earthquakes and comparison with Pleistocene sediments of the Taupo Volcanic Zone (TVZ)

    NASA Astrophysics Data System (ADS)

    Scholz, C.; Downs, D. T.; Gravley, D.; Quigley, M.; Rowland, J. V.

    2011-12-01

    The distinction between seismites and other event-related soft-sediment deformation is a challenging problem. Recognition and interpretation is aided by comparison of recent examples produced during known seismic events and those generated experimentally. Seismites are important features, once recognized in a rock, for interpretations of paleotectonic environment, tectonic relationships of sediments in basins, sedimentary facies analysis, evaluation of earthquake frequency and hazard and consequent land managment. Two examples of soft-sediment deformation, potentially generated through ground shaking and associated liquefaction, are described from within the TVZ: 1) Near Matata on the western margin of the Whakatane Graben. This location has a complicated en-echelon fault history and large earthquakes occur from time to time (e.g., 1987 ML6.3 Edgecumbe event). The structures occur in ~550 ka volcanic sediments, and represent soft-sediment deformation within stratigraphically-bounded layers. Based on paleoenvironment, appearance, and diagnostic criteria described by other authors (Sims 1975; Hempton and Dewey 1983), we interpret these features to have formed by ground shaking related to an earthquake and/or possibly accompanying large volcanic eruptions, rather than by slope failure. 2) Near Taupo, 3 km from the active Kaiapo fault. Lakeward dipping, nearly horizontal lacustrine sediments overlay Taupo Ignimbrite (1.8 ka). At one outcrop the lake beds have subsided into the underlying substrate resulting in kidney-shaped features. These structures formed as a result of liquefaction of the underlying substrate, which may have been caused by ground shaking related to either seismic or volcanic activity. However, inferred time relationships are more consistent with seismic-induced ground shaking. We compare and contrast the form and geometry of the above structures with seismites generated during the recent Christchurch earthquakes (Sep. 2010 and Feb. 2011). Hempton, M

  19. Global Earthquake and Volcanic Eruption Economic losses and costs from 1900-2014: 115 years of the CATDAT database - Trends, Normalisation and Visualisation

    NASA Astrophysics Data System (ADS)

    Daniell, James; Skapski, Jens-Udo; Vervaeck, Armand; Wenzel, Friedemann; Schaefer, Andreas

    2015-04-01

    Over the past 12 years, an in-depth database has been constructed for socio-economic losses from earthquakes and volcanoes. The effects of earthquakes and volcanic eruptions have been documented in many databases, however, many errors and incorrect details are often encountered. To combat this, the database was formed with socioeconomic checks of GDP, capital stock, population and other elements, as well as providing upper and lower bounds to each available event loss. The definition of economic losses within the CATDAT Damaging Earthquakes Database (Daniell et al., 2011a) as of v6.1 has now been redefined to provide three options of natural disaster loss pricing, including reconstruction cost, replacement cost and actual loss, in order to better define the impact of historical disasters. Similarly for volcanoes as for earthquakes, a reassessment has been undertaken looking at the historical net and gross capital stock and GDP at the time of the event, including the depreciated stock, in order to calculate the actual loss. A normalisation has then been undertaken using updated population, GDP and capital stock. The difference between depreciated and gross capital can be removed from the historical loss estimates which have been all calculated without taking depreciation of the building stock into account. The culmination of time series from 1900-2014 of net and gross capital stock, GDP, direct economic loss data, use of detailed studies of infrastructure age, and existing damage surveys, has allowed the first estimate of this nature. The death tolls in earthquakes from 1900-2014 are presented in various forms, showing around 2.32 million deaths due to earthquakes (with a range of 2.18 to 2.63 million) and around 59% due to masonry buildings and 28% from secondary effects. For the death tolls from the volcanic eruption database, 98000 deaths with a range from around 83000 to 107000 is seen from 1900-2014. The application of VSL life costing from death and injury

  20. Green-tuff landslide areas are beneficial for rice nutrition in Japan.

    PubMed

    Tazaki, Kazue

    2006-12-01

    Japanese Islands are covered with weathered volcanic rocks and soils. Terraced rice field are located in green-tuff areas which are very fertile but where landslides occur associated to strong earthquakes. The Xray diffraction and X-ray fluorescence analyses of the soils in landslide area identified predominant smectite and Mg, Al, Si, K, Ti, Mn and Fe are main components. The rice leaf showed that S, Cl, K and Ca play important roles for nutrients in the area. Drainpipe systems have set up in the green- tuff areas to reduce the risks of landslides. Reddish brown microbial mats inhabited bacteria and diatom in the drainpipe outlets. The microbial mats are rich in Fe and PO4(3-). The iron bacteria in the ground water have a high metabolic rate suggesting that the weathering materials were produced by not only physical and chemical influence but also by microorganism. Many microorganisms attach to mineral surfaces and show their high impact in the water mineral chemistry in the landslide area. Bacteria in the green-tuff over landslide area play important roles for sustainable agriculture including rice nutrition.

  1. Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

    NASA Astrophysics Data System (ADS)

    García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

    2014-06-01

    The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

  2. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

    NASA Astrophysics Data System (ADS)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

    2014-05-01

    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  3. Geostatistical analysis of the power-law exponents of the size distribution of earthquakes, Quaternary faults and monogenetic volcanoes in the Central Trans-Mexican Volcanic Belt

    NASA Astrophysics Data System (ADS)

    Mendoza-Ponce, A.; Perez Lopez, R.; Guardiola-Albert, C.; Garduño-Monroy, V. H.; Figueroa-Soto, Á.

    2017-12-01

    The Trans Mexican Volcanic Belt (TMVB) is related to the convergence between the Cocos and Rivera plates beneath the North American plate by the Middle America Trench (MAT). Moreover, there is also intraplate faulting within the TMVB, which is responsible of important earthquakes like the Acambay in 1912 (Mw 7.0) and Maravatío in 1979 (Mb 5.3). In this tectonic scheme, monogenetic volcanoes, active faulting and earthquakes configure a complex tectonic frame where different spatial anisotropy featured this activity. This complexity can be characterized by the power-law of the frequency-size distribution of the monogenetic volcanoes, the faults and the earthquakes. This power-law is determined by the b-value of the Gutenberg-Richter law in case of the earthquakes. The novelty of this work is the application of geostatistics techniques (variograms) for the analysis of spatial distribution of the b-values obtained from the size distribution of the basal diameter for monogenetic volcanoes in the Michoacán-Guanajuato Volcanic Field (bmv), surface area for faults in the Morelia-Acambay fault system (bf) and the seismicity in the Central TMVB (beq). Therefore, the anisotropy in each case was compared and a geometric tectonic model was proposed. The evaluation of the spatial distribution of the b-value maps gives us a general interpretation of the tectonic stress field and the seismic hazard in the zone. Hence, the beq-value map for the seismic catalog shows anomalously low and high values, reveling two different processes, one related to a typical tectonic rupture (low b-values) and the other one related to hydraulic fracturing (high b-values). The resulting bmv-map for the diameter basal cones indicates us the locations of the ages of the monogenetic volcanoes, giving important information about the volcanic hazard. High bmv-values are correlated with the presence of young cinder cones and an increasing probability of a new volcano. For the Morelia-Acambay fault system

  4. Improving Landslide Susceptibility Modeling Using an Empirical Threshold Scheme for Excluding Landslide Deposition

    NASA Astrophysics Data System (ADS)

    Tsai, F.; Lai, J. S.; Chiang, S. H.

    2015-12-01

    Landslides are frequently triggered by typhoons and earthquakes in Taiwan, causing serious economic losses and human casualties. Remotely sensed images and geo-spatial data consisting of land-cover and environmental information have been widely used for producing landslide inventories and causative factors for slope stability analysis. Landslide susceptibility, on the other hand, can represent the spatial likelihood of landslide occurrence and is an important basis for landslide risk assessment. As multi-temporal satellite images become popular and affordable, they are commonly used to generate landslide inventories for subsequent analysis. However, it is usually difficult to distinguish different landslide sub-regions (scarp, debris flow, deposition etc.) directly from remote sensing imagery. Consequently, the extracted landslide extents using image-based visual interpretation and automatic detections may contain many depositions that may reduce the fidelity of the landslide susceptibility model. This study developed an empirical thresholding scheme based on terrain characteristics for eliminating depositions from detected landslide areas to improve landslide susceptibility modeling. In this study, Bayesian network classifier is utilized to build a landslide susceptibility model and to predict sequent rainfall-induced shallow landslides in the Shimen reservoir watershed located in northern Taiwan. Eleven causative factors are considered, including terrain slope, aspect, curvature, elevation, geology, land-use, NDVI, soil, distance to fault, river and road. Landslide areas detected using satellite images acquired before and after eight typhoons between 2004 to 2008 are collected as the main inventory for training and verification. In the analysis, previous landslide events are used as training data to predict the samples of the next event. The results are then compared with recorded landslide areas in the inventory to evaluate the accuracy. Experimental results

  5. Landslides and Landscape Evolution

    NASA Astrophysics Data System (ADS)

    Densmore, A. L.; Hovius, N.

    2017-12-01

    Landslides have long been recognised as a major hazard, and are a common product of both large earthquakes and rainstorms. Our appreciation for landslides as agents of erosion and land surface evolution, however, is much more recent. Only in the last twenty years have we come to understand the critical role that landslides play at the landscape scale: in allowing hillslopes to keep pace with fluvial incision, in supplying sediment to channel networks and sedimentary basins, in divide migration, and in setting the basic structure of the landscape. This perspective has been made possible in part by repeat remote sensing and new ways of visualising the land surface, and by extending our understanding of failure processes to the landscape scale; but it is also true that the big jumps in our knowledge have been triggered by large events, such as the 1999 Chi-Chi and 2008 Wenchuan earthquakes. Thanks in part to a relative handful of such case studies, we now have a better idea of the spatial distribution of landslides that are triggered in large events, the volume of sediment that they mobilise, the time scales over which that sediment is mobilised and evacuated, and the overall volume balance between erosion and tectonic processes in the growth of mountainous topography. There remain, however, some major challenges that must still be overcome. Estimates of landslide volume remain highly uncertain, as does our ability to predict the evolution of hillslope propensity to failure after a major triggering event, the movement of landslide sediment (especially the coarse fraction that is transported as bedload), and the impact of landslides on both long-term erosion rates and tectonic processes. The limited range of case studies also means that we struggle to predict outcomes for triggering events in different geological settings, such as loess landscapes or massive lithologies. And the perspective afforded by taking a landscape-scale view has yet to be fully reflected in our

  6. Regional coseismic landslide hazard assessment without historical landslide inventories: A new approach

    NASA Astrophysics Data System (ADS)

    Kritikos, Theodosios; Robinson, Tom R.; Davies, Tim R. H.

    2015-04-01

    Currently, regional coseismic landslide hazard analyses require comprehensive historical landslide inventories as well as detailed geotechnical data. Consequently, such analyses have not been possible where these data are not available. A new approach is proposed herein to assess coseismic landslide hazard at regional scale for specific earthquake scenarios in areas without historical landslide inventories. The proposed model employs fuzzy logic and geographic information systems to establish relationships between causative factors and coseismic slope failures in regions with well-documented and substantially complete coseismic landslide inventories. These relationships are then utilized to estimate the relative probability of landslide occurrence in regions with neither historical landslide inventories nor detailed geotechnical data. Statistical analyses of inventories from the 1994 Northridge and 2008 Wenchuan earthquakes reveal that shaking intensity, topography, and distance from active faults and streams are the main controls on the spatial distribution of coseismic landslides. Average fuzzy memberships for each factor are developed and aggregated to model the relative coseismic landslide hazard for both earthquakes. The predictive capabilities of the models are assessed and show good-to-excellent model performance for both events. These memberships are then applied to the 1999 Chi-Chi earthquake, using only a digital elevation model, active fault map, and isoseismal data, replicating prediction of a future event in a region lacking historic inventories and/or geotechnical data. This similarly results in excellent model performance, demonstrating the model's predictive potential and confirming it can be meaningfully applied in regions where previous methods could not. For such regions, this method may enable a greater ability to analyze coseismic landslide hazard from specific earthquake scenarios, allowing for mitigation measures and emergency response plans

  7. Non-double-couple earthquakes. 1. Theory

    Julian, B.R.; Miller, A.D.; Foulger, G.R.

    1998-01-01

    Historically, most quantitative seismological analyses have been based on the assumption that earthquakes are caused by shear faulting, for which the equivalent force system in an isotropic medium is a pair of force couples with no net torque (a 'double couple,' or DC). Observations of increasing quality and coverage, however, now resolve departures from the DC model for many earthquakes and find some earthquakes, especially in volcanic and geothermal areas, that have strongly non-DC mechanisms. Understanding non-DC earthquakes is important both for studying the process of faulting in detail and for identifying nonshear-faulting processes that apparently occur in some earthquakes. This paper summarizes the theory of 'moment tensor' expansions of equivalent-force systems and analyzes many possible physical non-DC earthquake processes. Contrary to long-standing assumption, sources within the Earth can sometimes have net force and torque components, described by first-rank and asymmetric second-rank moment tensors, which must be included in analyses of landslides and some volcanic phenomena. Non-DC processes that lead to conventional (symmetric second-rank) moment tensors include geometrically complex shear faulting, tensile faulting, shear faulting in an anisotropic medium, shear faulting in a heterogeneous region (e.g., near an interface), and polymorphic phase transformations. Undoubtedly, many non-DC earthquake processes remain to be discovered. Progress will be facilitated by experimental studies that use wave amplitudes, amplitude ratios, and complete waveforms in addition to wave polarities and thus avoid arbitrary assumptions such as the absence of volume changes or the temporal similarity of different moment tensor components.

  8. Into the complexity of coseismic landslide clustering

    NASA Astrophysics Data System (ADS)

    Meunier, Patrick; Marc, Odin; Uchida, Taro; Hovius, Niels

    2014-05-01

    Earthquake-triggered landslides tend to cluster along topographic crests while rainfall-induced landslides are more uniformly distributed on hillslopes [1]. In theory, rainfall induced landslides should even occur downslope preferentially, where pore pressure induced by groundwater flows is the highest. Past studies on landslide clustering are all based on the analysis of complete dataset or subdataset of landslides associated with a given event (seismic or climatic) as a whole. In this work, we document the spatial variation of the landslide position (on hillslopes) within the epicentral area for the cases of the 1999 Chichi, the 2004 Niigata and the 2008 Iwate earthquakes. We show that landslide clustering is not uniform in space and exhibit patterns that vary a lot from one case to another. These patterns are not easy to interpret as they don't seem to be controlled by a single governing parameter but result from a complex interaction between local (hillslope length and gradient, lithology) and seismic (distance to source, slope aspect, radiation pattern, coseismic uplift) parameters. [1] Meunier, P., Hovius, N., & Haines, J. A. (2008). Topographic site effects and the location of earthquake induced landslides. Earth and Planetary Science Letters, 275(3), 221-232.

  9. Using a UAV for collecting information about a deep-seated landslide in the island of Lefkada following the 17 November 2015 strike-slip earthquake (M=6.5)

    NASA Astrophysics Data System (ADS)

    Valkaniotis, Sotirios; Ganas, Athanassios; Papathanassiou, George

    2017-04-01

    Documentation of landslides is a very critical issue because effective protection and mitigation measures can be designed only if they are based on the accuracy of the provided information. Such a documentation aims at a detailed description of the basic geomorphological features e.g. edge, traces, scarp etc. while variables such as the landslide area and the volume of the area (that moved) are also measured. However, it is well known that the mapping of these features is not always feasible due to several adverse factors e.g. vertical slopes, high risk. In order to overcome this issue, remote sensing techniques were applied during the last decades. In particular, Interferometric Synthetic Aperture Radar (InSAR), Light Detection and Ranging (LiDAR) and photogrammetric surveys are used for geomorphic mapping in order to quantify landslide processes. The latter one, photogrammetric survey, is frequently conducted by use of Unmanned Aerial Vehicles (UAV), such as multicopters that are flexible in operating conditions and can be equipped with webcams, digital cameras and other sensors. In addition, UAV is considered as a low-cost imaging technique that offers a very high spatial-temporal resolution and flexibility in data acquisition programming. The goal of this study is to provide quantitative data regarding a deep-seated landslide triggered by the 17 November 2015, Greece earthquake (M=6.5; Ganas et al., 2016) in a coastal area of Lefkada, that was not accessible by foot and accordingly, a UAV was used in order to collect the essential information. Ganas, A., et al., Tectonophysics, http://dx.doi.org/10.1016/j.tecto.2016.08.012

  10. Volcanic rock properties control sector collapse events

    NASA Astrophysics Data System (ADS)

    Hughes, Amy; Kendrick, Jackie; Lavallée, Yan; Hornby, Adrian; Di Toro, Giulio

    2017-04-01

    Volcanoes constructed by superimposed layers of varying volcanic materials are inherently unstable structures. The heterogeneity of weak and strong layers consisting of ash, tephra and lavas, each with varying coherencies, porosities, crystallinities, glass content and ultimately, strength, can promote volcanic flank and sector collapses. These volcanoes often exist in areas with complex regional tectonics adding to instability caused by heterogeneity, flank overburden, magma movement and emplacement in addition to hydrothermal alteration and anomalous geothermal gradients. Recent studies conducted on the faulting properties of volcanic rocks at variable slip rates show the rate-weakening dependence of the friction coefficients (up to 90% reduction)[1], caused by a wide range of factors such as the generation of gouge and frictional melt lubrication [2]. Experimental data from experiments conducted on volcanic products suggests that frictional melt occurs at slip rates similar to those of plug flow in volcanic conduits [1] and the bases of mass material movements such as debris avalanches from volcanic flanks [3]. In volcanic rock, the generation of frictional heat may prompt the remobilisation of interstitial glass below melting temperatures due to passing of the glass transition temperature at ˜650-750 ˚C [4]. In addition, the crushing of pores in high porosity samples can lead to increased comminution and strain localisation along slip surfaces. Here we present the results of friction tests on both high density, glass rich samples from Santaguito (Guatemala) and synthetic glass samples with varying porosities (0-25%) to better understand frictional properties underlying volcanic collapse events. 1. Kendrick, J.E., et al., Extreme frictional processes in the volcanic conduit of Mount St. Helens (USA) during the 2004-2008 eruption. J. Structural Geology, 2012. 2. Di Toro, G., et al., Fault lubrication during earthquakes. Nature, 2011. 471(7339): p. 494-498. 3

  11. Comparison of earthquake source characteristics in the Kachchh Rift Basin and Saurashtra horst, Deccan Volcanic Province, western India

    NASA Astrophysics Data System (ADS)

    Sairam, B.; Singh, A. P.; Ravi Kumar, M.

    2018-06-01

    Seismic source parameters of small to moderate sized intraplate earthquakes that occurred during 2002-2009 in the tectonic blocks of Kachchh Rift Basin (KRB) and the Saurashtra Horst (SH), in the stable continental region of western peninsular India, are studied through spectral analysis of shear waves. The data of aftershock sequence of the 2001 Bhuj earthquake (Mw 7.7) in the KRB and the 2007 Talala earthquake (Mw 5.0) in the SH are used for this study. In the SH, the seismic moment (Mo), corner frequency (fc), stress drop (Δ σ ) and source radius ( r) vary from 7.8× 10^{11} to 4.0× 10^{16} N-m, 1.0-8.9 Hz, 4.8-10.2 MPa and 195-1480 m, respectively. While in the KRB, these parameters vary from Mo ˜ 1.24 × 10^{11} to 4.1 × 10^{16} N-m, f_{c }˜ 1.6 to 13.1 Hz, Δ σ ˜ 0.06 to 16.62 MPa and r ˜ 100 to 840 m. The kappa ( K) value in the KRB (0.025-0.03) is slightly larger than that in the SH region (0.02), probably due to thick sedimentary layers. The estimated stress drops of earthquakes in the KRB are relatively higher than those in SH, due to large crustal stress concentration associated with mafic/ultramafic rocks at the hypocentral depths. The results also suggest that the stress drop value of intraplate earthquakes is larger than the interplate earthquakes. In addition, it is observed that the strike-slip events in the SH have lower stress drops, compared to the thrust and strike-slip events.

  12. Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge

    Vidale, John E.; Schmidt, David A.; Malone, Stephen D.; Hotovec-Ellis, Alicia J.; Moran, Seth C.; Creager, Kenneth C.; Houston, Heidi

    2014-01-01

    Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

  13. Rainfall Induced Landslides in Puerto Rico (Invited)

    NASA Astrophysics Data System (ADS)

    Lepore, C.; Kamal, S.; Arnone, E.; Noto, V.; Shanahan, P.; Bras, R. L.

    2009-12-01

    Landslides are a major geologic hazard in the United States, typically triggered by rainfall, earthquakes, volcanoes and human activity. Rainfall-induced landslides are the most common type in the island of Puerto Rico, with one or two large events per year. We performed an island-wide determination of static landslide susceptibility and hazard assessment as well as dynamic modeling of rainfall-induced shallow landslides in a particular hydrologic basin. Based on statistical analysis of past landslides, we determined that reliable prediction of the susceptibility to landslides is strongly dependent on the resolution of the digital elevation model (DEM) employed and the reliability of the rainfall data. A distributed hydrology model capable of simulating landslides, tRIBS-VEGGIE, has been implemented for the first time in a humid tropical environment like Puerto Rico. The Mameyes basin, located in the Luquillo Experimental Forest in Puerto Rico, was selected for modeling based on the availability of soil, vegetation, topographical, meteorological and historic landslide data. .Application of the model yields a temporal and spatial distribution of predicted rainfall-induced landslides, which is used to predict the dynamic susceptibility of the basin to landslides.

  14. Crystallisation ages in coeval silicic magma bodies: 238U-230Th disequilibrium evidence from the Rotoiti and earthquake flat eruption deposits, Taupo volcanic zone, New Zealand

    Charlier, B.L.A.; Peate, D.W.; Wilson, C.J.N.; Lowenstern, J. B.; Storey, M.; Brown, S.J.A.

    2003-01-01

    The timescales over which moderate to large bodies of silicic magma are generated and stored are addressed here by studies of two geographically adjacent, successive eruption deposits in the Taupo Volcanic Zone, New Zealand. The earlier, caldera-forming Rotoiti eruption (>100 km3 magma) at Okataina volcano was followed, within months at most, by the Earthquake Flat eruption (??? 10 km3 magma) from nearby Kapenga volcano; both generated nonwelded ignimbrite and coeval widespread fall deposits. The Rotoiti and Earthquake Flat deposits are both crystal-rich high-silica rhyolites, with sparse glass-bearing granitoid fragments also occurring in Rotoiti lag breccias generated during caldera collapse. Here we report 238U-230Th disequilibrium data on whole rocks and mineral separates from representative Rotoiti and Earthquake Flat pumices and the co-eruptive Rotoiti granitoid fragments using TIMS and in situ zircon analyses by SIMS. Multiple-grain zircon-controlled crystallisation ages measured by TIMS from the Rotoiti pumice range from 69??3 ka ( 350 ka, with a pronounced peak at 70-90 ka. The weighted mean of isochrons is 83??14 ka, in accord with the TIMS data. One glass-bearing Rotoiti granitoid clast yielded an age of 57??8 ka by TIMS (controlled by Th-rich phases that, however, are not apparently present in the juvenile pumices). Another glass-bearing Rotoiti granitoid yielded SIMS zircon model ages peaking at 60-90 ka, having a similar age distribution to the pumice. Age data from pumices are consistent with a published 64??4 ka eruptive age (now modified to 62??2 ka), but chemical and/or mineralogical data imply that the granitoid lithics are not largely crystalline Rotoiti rhyolite, but instead represent contemporaneous partly molten intrusions reflecting different sources in their chemistries and mineralogies. Similarly, although the Earthquake Flat eruption immediately followed (and probably was triggered by) the Rotoiti event, age data from juvenile material

  15. Recovery process of shear wave velocities of volcanic soil in central Mashiki Town after the 2016 Kumamoto earthquake revealed by intermittent measurements of microtremor

    NASA Astrophysics Data System (ADS)

    Hata, Yoshiya; Yoshimi, Masayuki; Goto, Hiroyuki; Hosoya, Takashi; Morikawa, Hitoshi; Kagawa, Takao

    2017-05-01

    An earthquake of JMA magnitude 6.5 (foreshock) hit Kumamoto Prefecture, Japan, at 21:26 JST on April 14, 2016. Subsequently, an earthquake of JMA magnitude 7.3 (main shock) hit Kumamoto and Oita Prefectures at 1:25 JST on April 16, 2016. The two epicenters were located adjacent to central Mashiki Town, and both events caused significantly strong motions. The heavy damage including collapse of residential houses was concentrated in "Sandwich Area" between Prefectural Route 28 and Akitsu River. During the main shock, we have successfully observed strong motions at TMP03 in Sandwich Area. Simultaneously with installation of the seismograph at TMP03 on April 15, 2016, between the foreshock and the main shock, a microtremor measurement was taken. After the main shock, intermittent measurements of microtremor at TMP03 were also taken within December 6, 2016. As the result, recovery process of shear wave velocities of volcanic soil at TMP03 before/after the main shock was revealed by time history of peak frequencies of the microtremor H/V spectra. Using results of original PS logging tests at proximity site of TMP03 on July 28, 2016, the applicability for the shear wave velocities to TMP03 was then confirmed based on similarity between the theoretical and monitored H/V spectra.

  16. An analysis of on time evolution of landslide

    NASA Astrophysics Data System (ADS)

    Tsai, Chienwei; Lien, Huipang

    2017-04-01

    In recent years, the extreme hydrological phenomenon in Taiwan is obvious. Because the increase of heavy rainfall frequency has resulted in severe landslide disaster, the watershed management is very important and how to make the most effective governance within the limited funds is the key point. In recent years many scholars to develop empirical models said that virtually rainfall factors exist and as long as rainfall conditions are met the minimum requirements of the model, landslide will occur. However, rainfall is one of the elements to the landslide, but not the only one element. Rainfall, geology and earthquake all contributed to the landslide as well. Preliminary research found that many landslides occur at the same location constantly and after repeating landslide, the slope had the characteristic of landslide immunity over time, even if the rainfall exceeded the standard, the landslide could not be triggered in the near term. This study investigated the surface conditions of slope that occur repeated landslide. It is difficult to be the basis of subsequent anti-disaster if making rainfall is the only condition to contribute to the landslide. This study analyzes 50 landslides in 2004 2013. Repeated landslide is defined as existed landslide in satellite images of reference period which it's bare area is shrinking or disappearing gradually but the restoration occur landslide again in some period time. The statistical analysis of the study found that 96% of landslide has repeated landslide and on average repeated landslide occurs 3.4 years in 10 years by one year as the unit. The highest of repeated landslide happened in 2010. It would presume that Typhoon Morakot in 2010 brought torrential rain which suffered southern mountain areas severely so the areas occurred repeated landslide.

  17. Seismic Triggers of Lacustrine Subaqueous Landslides in Lake Champlain, USA

    NASA Astrophysics Data System (ADS)

    Manley, P.; Manley, T.; Ghosh, S. J.; Rosales-Underbrink, P.; Silverhart, P.

    2017-12-01

    Lacustrine slumps and debris flows (landslides) have been identified in Lake Champlain via Multibeam and CHIRP (compressed high intensity radar pulse) seismic profile data. Numerous large landslides studied by Ghosh (2012), Rosales-Underbrink (2015), and Silverhart (2016) have shown that many of these landslides are coeval. All landslides failed on a specific interface between marine Champlain Sea and modern lacustrine Lake Champlain sediments. Utilizing radionuclide dating on sediment from the unfailed slopes or undisturbed sediment above failed deposits, sedimentation rates were determined and used to calculate the approximate failure ages for each of the landslides studied. The northernmost failure, south of the Bouquet River, occurred about 950-1200 cal yr BP and is the first mass wasting event of this age to be recorded on Lake Champlain. The remaining landslides failed about 4500-5200 cal yr BP and agree with nearby Western Quebec Seismic Zone (WQSZ) with clusters of terrestrial landslides occurring at 1000 and 5000 cal yr BP triggered by large earthquakes (Brooks, 2015) along the same interface. The 5000 cal yr BP event has been attributed to a M 6.4 or greater earthquake within the WQSZ. The coeval landslides observed in Lake Champlain were likely triggered by this same earthquake. Lake tsunami models show that these simultaneous landslide failures can generate surface waves wave that can impact the Lake Champlain shoreline within 3-10 minutes after the earthquake.

  18. Fear based Education or Curiosity based Education as an Example of Earthquake and Natural Disaster Education: Results of Statistical Study in Primary Schools in Istanbul-Turkey

    NASA Astrophysics Data System (ADS)

    Ozcep, T.; Ozcep, F.

    2012-04-01

    ?", "Could earthquake be predicted ?", "Does earthquake kill people or buildings ?", "What is fault?", "Who is earthquake scientist?", "Are the Moon, Sun and other planets caused the earthquake?", "Does the weather conditions trigger the earthquake?", "What is the cause of tsunami?", "What is cause of the flood?", " What is the cause of volcanic eruption?", "What is cause of the landslide?", "What is the cause of disasters?", "What is your feeling about the earthquake; curiosity or fear?". Answers of these questions are evaluated. In the result, the primary school students think that earthquakes and other events are both religious and scientific origin. As example; the answers of "What is your feeling about the earthquake; corusity or fear?" question are replied 81 % Fear and %19 Curiosity.

  19. USGS Earthquake Program GPS Use Case : Earthquake Early Warning

    DOT National Transportation Integrated Search

    2015-03-12

    USGS GPS receiver use case. Item 1 - High Precision User (federal agency with Stafford Act hazard alert responsibilities for earthquakes, volcanoes and landslides nationwide). Item 2 - Description of Associated GPS Application(s): The USGS Eart...

  20. Studying onshore-offshore fault linkages and landslides in Icy Bay and Taan Fjord to assess geohazards in Southeast Alaska

    NASA Astrophysics Data System (ADS)

    McCall, N.; Walton, M. A. L.; Gulick, S. P. S.; Haeussler, P. J.; Reece, R.; Saustrup, S.

    2016-12-01

    In southeast Alaska, the plate boundary where the Yakutat microplate collides with North America has produced large historical earthquakes (i.e., the Mw 8+ 1899 sequence). Despite the seismic potential, the possible source fault systems for these earthquakes have not been imaged with modern methods in Icy Bay. The offshore Pamplona Zone and its eastward onshore extension, the Malaspina Fault, may have played a role in the September 1899 earthquakes. Onshore and offshore mapping indicates that these structures likely connect offshore in Icy Bay. In August 2016 we collected high-resolution (300-1200 Hz) seismic reflection and multibeam bathymetry data to search for evidence of such faults beneath Icy Bay and Taan Fiord. If the Malaspina Fault is found to link with the Pamplona Zone, a rupture could trigger a tsunami impacting the populated regions in southeast Alaska. More recently, on October 17th 2015, nearby Taan Fjord experienced one of the largest non-volcanic landslides recorded in North America. Approximately 200 million metric tons spilled into Taan Fjord creating a tsunami with waves reaching 150m onshore. Using the new data, we are capable of imaging landslide and tsunami deposits in high-resolution. These data give new constraints for onshore-offshore fault systems, giving us new insights into the earthquake and tsunami hazard in southeast Alaska.

  1. Maps Showing Seismic Landslide Hazards in Anchorage, Alaska

    Jibson, Randall W.; Michael, John A.

    2009-01-01

    The devastating landslides that accompanied the great 1964 Alaska earthquake showed that seismically triggered landslides are one of the greatest geologic hazards in Anchorage. Maps quantifying seismic landslide hazards are therefore important for planning, zoning, and emergency-response preparation. The accompanying maps portray seismic landslide hazards for the following conditions: (1) deep, translational landslides, which occur only during great subduction-zone earthquakes that have return periods of =~300-900 yr; (2) shallow landslides for a peak ground acceleration (PGA) of 0.69 g, which has a return period of 2,475 yr, or a 2 percent probability of exceedance in 50 yr; and (3) shallow landslides for a PGA of 0.43 g, which has a return period of 475 yr, or a 10 percent probability of exceedance in 50 yr. Deep, translational landslide hazard zones were delineated based on previous studies of such landslides, with some modifications based on field observations of locations of deep landslides. Shallow-landslide hazards were delineated using a Newmark-type displacement analysis for the two probabilistic ground motions modeled.

  2. Maps showing seismic landslide hazards in Anchorage, Alaska

    Jibson, Randall W.

    2014-01-01

    The devastating landslides that accompanied the great 1964 Alaska earthquake showed that seismically triggered landslides are one of the greatest geologic hazards in Anchorage. Maps quantifying seismic landslide hazards are therefore important for planning, zoning, and emergency-response preparation. The accompanying maps portray seismic landslide hazards for the following conditions: (1) deep, translational landslides, which occur only during great subduction-zone earthquakes that have return periods of =300-900 yr; (2) shallow landslides for a peak ground acceleration (PGA) of 0.69 g, which has a return period of 2,475 yr, or a 2 percent probability of exceedance in 50 yr; and (3) shallow landslides for a PGA of 0.43 g, which has a return period of 475 yr, or a 10 percent probability of exceedance in 50 yr. Deep, translational landslide hazards were delineated based on previous studies of such landslides, with some modifications based on field observations of locations of deep landslides. Shallow-landslide hazards were delineated using a Newmark-type displacement analysis for the two probabilistic ground motions modeled.

  3. Automatic Detection of Landslides at Stromboli Volcano

    NASA Astrophysics Data System (ADS)

    Giudicepietro, F.; Esposito, A. M.; D'Auria, L.; Peluso, R.; Martini, M.

    2011-12-01

    In this work we present an automatic system for the landslide detection at Stromboli volcano that has proved to be effective both during the 2007 effusive eruption and in the recent (2 August 2011) volcanic activity. The study of the landslides at Stromboli is important because they could be considered short-term precursors of effusive eruptions, as seen during the 2007 eruption, and in addition they allow to improve the monitoring of the gravitational instabilities of the Sciara del Fuoco flank. The proposed system uses a two-class MLP (Multi Layer Perceptron) neural network in order to discriminate the landslides from other seismic signals usually recorded at Stromboli, such as explosion-quakes and volcanic tremor. To train and test the network we used a dataset of 537 signals, including 267 landslides and 270 other events (130 explosion-quakes and 140 tremor signals). The net performance is of 98.7%, if averaged over different net configurations, and of 99.5% for the best net performance. Based on the neural network response, the automatic system calculates a Landslide Percentage Index (LPI) defined on the number of signals identified as landslides by the net on a given temporal interval in order to recognize anomalies in the landslide rate. This system was sensitive to the signals produced by the flow of lava front during a recent mild effusive episode on the "La Sciara del Fuoco" slope.

  4. Venus - Landslide in Navka Region

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Magellan spacecraft has observed remnant landslide deposits apparently resulting from the collapse of volcanic structures. This Magellan radar image is centered about 25.4 degrees south latitude and 308 degrees east longitude in the southwestern Navka Region of Venus. The image shows a 17.4 kilometer (10.8 mile) diameter volcanic dome on the plains. The dome is approximately 1.86 kilometers (1.2 mile) in height and it has a slope of about 23 degrees. The northwest and northeast flanks of the dome have collapsed to form landslides that have deposited debris on the plains. The image shows an area 110 kilometers (68 miles) across and 100 kilometers (62 miles) in length.

  5. Characterizing long-term radon concentration changes in a geothermal area for correlation with volcanic earthquakes and reservoir temperatures: A case study from Mt. Aso, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Koike, Katsuaki; Yoshinaga, Tohru; Asaue, Hisafumi

    2014-04-01

    The purpose of this study is to characterize in detail the temporal changes in Rn (radon-222) concentration in soil gases near fumaroles and clarify its correlation with volcanic earthquakes and temperatures in two geothermal reservoirs. Mt. Aso crater in southwest Japan, which has two reservoirs on its western side estimated by magnetotelluric survey to be at about 2 km in depth, was selected for this study. For the long-term survey, the α scintillation counter method was used weekly for 12.5 years at the three hot springs within a 2-km range. Rn concentrations were calculated using the CRAS method, a calculation method that considers radioactive equilibrium or nonequilibrium state of the soil gas. Rn concentrations generally showed similar fluctuation patterns among the sites. CRAS was used as a new indicator for evaluating the age of the soil gas. This age corresponds to the elapsed time determined from the generation of Rn based on the measurement of the numbers of atoms of Rn and its daughter 218Po at the start of measurement. In comparing the Rn data with the history of earthquakes in the Aso caldera, volcanic seismicity was identified as a major controlling factor in the sudden increase and decrease in Rn concentration as a function of age. For more precise detections of change, Rn concentrations were measured continuously at one site by pumping soil gas from a borehole and using an ionization chamber over 2.5 years. Five chemical components (He, H2, N2, CH4, and CO2) were then measured by gas chromatography at 1-week intervals. Because Rn concentrations are affected strongly by atmospheric temperatures, the residual components were obtained by subtracting the trend of the components from the original data. Chemical component data were used to estimate the temperature and pressure in the reservoir at the site; temperatures ranged from 229 to 280 °C, (average 265 °C, average pressure 80 MPa). Residual Rn concentrations showed a clear correlation with

  6. Responses to, and the short and long-term impacts of, the 1957/1958 Capelinhos volcanic eruption and associated earthquake activity on Faial, Azores

    NASA Astrophysics Data System (ADS)

    Coutinho, Rui; Chester, David K.; Wallenstein, Nicolau; Duncan, Angus M.

    2010-10-01

    The 1957/58 Capelinhos eruption on Faial Island in the Azores is well known for being an excellent example of Surtseyan hydromagmatic volcanic activity. Less well known are the responses of the Portuguese authorities to the eruption and subsequent earthquake in May 1958, and the ways in which well-thought-out and generally effective recovery programmes were put in place. At the time Portugal was ruled by a dictatorship, the Estado Novo (New State). Only superficially similar to other fascist governments in Southern Europe, the Estado Novo collected huge amounts of data on the responses of the authorities to the disaster and their programmes of recovery, but never encouraged academic evaluation of policy, although it ensured that the scientific aspects of the eruption and earthquake were meticulously recorded and published. In this paper we remedy this situation by discussing the details of the immediate response to the emergency and the ways in which the island recovered in its aftermath. The study is based not only on archival sources and demographic and economic data, but also on detailed interviews with survivors some of whom were also decision makers. We argue that response, recovery and rehabilitation were generally highly successful and assess the lessons of the 1957/58 emergency which are relevant to future geophysical disasters in Faial and the wider Azores. Since the 1974 revolution Portugal has been a democratic state. We conclude that both the legislation and the civil defence infrastructure, necessary to achieve a similarly strong and successful response, are in place today.

  7. Seismic response of soft deposits due to landslide: The Mission Peak, California, landslide

    Hartzell, Stephen; Leeds, Alena L.; Jibson, Randall W.

    2017-01-01

    The seismic response of active and intermittently active landslides is an important issue to resolve to determine if such landslides present an elevated hazard in future earthquakes. To study the response of landslide deposits, seismographs were placed on the Mission Peak landslide in the eastern San Francisco Bay region for a period of one year. Numerous local and near‐regional earthquakes were recorded that reveal a complexity of seismic response phenomena using the horizontal‐to‐vertical spectral ratio method. At lower frequencies, a clear spectral peak is observed at 0.5 Hz common to all four stations in the array and is attributed to a surface topographic effect. At higher frequencies, other spectral peaks occur that are interpreted in terms of local deposits and structures. Site amplification from the standard reference site method shows the minimum amplification with a factor of 2, comparing a site on and off the landslide. A site located on relatively homogeneous deposits of loose soils shows a clear spectral peak associated with the thickness of the deposit. Another site on a talus‐filled graben near the headscarp shows possible 2D or 3D effects from subsurface topography or scattering within and between buried sandstone blocks. A third site on a massive partially detached block below the crown of the headscarp shows indications of resonance caused by the reverberation of shear waves within the block. The varied seismic response of different parts of this complex landslide is consistent with other studies which found that, although landslide response is commonly enhanced in the downslope direction of landslide movement, such a response does not occur uniformly or consistently. When it does occur, enhanced site response parallel to the direction of landslide movement would contribute to landslide reactivation during significant earthquakes.

  8. Development of double-pair double difference location algorithm and its application to the regular earthquakes and non-volcanic tremors

    NASA Astrophysics Data System (ADS)

    Guo, H.; Zhang, H.

    2016-12-01

    Relocating high-precision earthquakes is a central task for monitoring earthquakes and studying the structure of earth's interior. The most popular location method is the event-pair double-difference (DD) relative location method, which uses the catalog and/or more accurate waveform cross-correlation (WCC) differential times from event pairs with small inter-event separations to the common stations to reduce the effect of the velocity uncertainties outside the source region. Similarly, Zhang et al. [2010] developed a station-pair DD location method which uses the differential times from common events to pairs of stations to reduce the effect of the velocity uncertainties near the source region, to relocate the non-volcanic tremors (NVT) beneath the San Andreas Fault (SAF). To utilize advantages of both DD location methods, we have proposed and developed a new double-pair DD location method to use the differential times from pairs of events to pairs of stations. The new method can remove the event origin time and station correction terms from the inversion system and cancel out the effects of the velocity uncertainties near and outside the source region simultaneously. We tested and applied the new method on the northern California regular earthquakes to validate its performance. In comparison, among three DD location methods, the new double-pair DD method can determine more accurate relative locations and the station-pair DD method can better improve the absolute locations. Thus, we further proposed a new location strategy combining station-pair and double-pair differential times to determine accurate absolute and relative locations at the same time. For NVTs, it is difficult to pick the first arrivals and derive the WCC event-pair differential times, thus the general practice is to measure station-pair envelope WCC differential times. However, station-pair tremor locations are scattered due to the low-precision relative locations. The ability that double-pair data

  9. A new view into the Cascadia subduction zone and volcanic arc: Implications for earthquake hazards along the Washington margin

    Parsons, T.; Trehu, A.M.; Luetgert, J.H.; Miller, K.; Kilbride, F.; Wells, R.E.; Fisher, M.A.; Flueh, E.; ten Brink, Uri S.; Christensen, N.I.

    1998-01-01

    In light of suggestions that the Cascadia subduction margin may pose a significant seismic hazard for the highly populated Pacific Northwest region of the United States, the U.S. Geological Survey (USGS), the Research Center for Marine Geosciences (GEOMAR), and university collaborators collected and interpreted a 530-km-long wide-angle onshore-offshore seismic transect across the subduction zone and volcanic arc to study the major structures that contribute to seismogenic deformation. We observed (1) an increase in the dip of the Juan de Fuca slab from 2°–7° to 12° where it encounters a 20-km-thick block of the Siletz terrane or other accreted oceanic crust, (2) a distinct transition from Siletz crust into Cascade arc crust that coincides with the Mount St. Helens seismic zone, supporting the idea that the mafic Siletz block focuses seismic deformation at its edges, and (3) a crustal root (35–45 km deep) beneath the Cascade Range, with thinner crust (30–35 km) east of the volcanic arc beneath the Columbia Plateau flood basalt province. From the measured crustal structure and subduction geometry, we identify two zones that may concentrate future seismic activity: (1) a broad (because of the shallow dip), possibly locked part of the interplate contact that extends from ∼25 km depth beneath the coastline to perhaps as far west as the deformation front ∼120 km offshore and (2) a crustal zone at the eastern boundary between the Siletz terrane and the Cascade Range.

  10. Seismically induced landslides: current research by the US Geological Survey.

    Harp, E.L.; Wilson, R.C.; Keefer, D.K.; Wieczorek, G.F.

    1986-01-01

    We have produced a regional seismic slope-stability map and a probabilistic prediction of landslide distribution from a postulated earthquake. For liquefaction-induced landslides, in situ measurements of seismically induced pore-water pressures have been used to establish an elastic model of pore pressure generation. -from Authors

  11. Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington

    Harrington, Rebecca M.; Kwiatek, Grzegorz; Moran, Seth C.

    2015-01-01

    We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation coefficient of 0.8 or greater with at least five other events. A cluster analysis of cross-correlation values indicates that the group of 421 events meeting the SNR and cross-correlation criteria forms eight event families that exhibit largely self-similar scaling. We estimate the M0 and f0 values of the 421 events and calculate their static stress drop and scaled energy (ER/M0) values. The estimated values suggest self-similar scaling within families, as well as between five of eight families (i.e.,  and  constant). We speculate that differences in scaled energy values for the two families with variable scaling may result from a lack of resolution in the velocity model. The observation of self-similar scaling is the first of its kind for such a large group of low-frequency volcanic tectonic events occurring during a single active dome extrusion eruption.

  12. Slow slip in the focal region of the anticipated Tokai earthquake following the seismo-volcanic event in the northern Izu Islands in 2000

    NASA Astrophysics Data System (ADS)

    Kobayashi, Akio; Yoshida, Akio; Yamamoto, Takeyasu; Takayama, Hiromi

    2005-06-01

    Transient crustal deformation occurred in the regions of Kanto and Tokai during the seismo-volcanic event in the northern Izu Islands in 2000. In our investigation of the observed deformation, we constructed an optimum-source model of the event between Miyake and Kozu Islands. We then made an inversion analysis of the differences between the observed displacement field and the calculated displacement field from the optimum model, assuming that the differences were caused by the changes in the interplate coupling beneath the Tokai region. From the inversion analysis of data for each of three-month periods, May to August, June to September, and July to October, we found decreased interplate coupling in the early stages of the 2000 event. In the first stage, either a slow slip or a temporary suspension of the plate subduction occurred in the focal region of the anticipated Tokai earthquake. The area then extended to the west and, finally, a slow slip exceeded the secular convergence velocity on the plate interface near Lake Hamana in the fall of 2000. We believe this ongoing slow slip began in August or early September 2000.

  13. Landslide Hazards

    ,

    2000-01-01

    Landslide hazards occur in many places around What Can You Do If You Live Near Steep Hills? the world and include fast-moving debris flows, slow-moving landslides, and a variety of flows and slides initiating from volcanoes. Each year, these hazards cost billions of dollars and cause numerous fatalities and injuries. Awareness and education about these hazards is a first step toward reducing damaging effects. The U.S. Geological Survey conducts research and distributes information about geologic hazards. This Fact Sheet is published in English and Spanish and can be reproduced in any form for further distribution. 

  14. Preliminary ground response of the Diezma landslide (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Delgado, José; García-Tortosa, Francisco J.; Garrido, Jesús; Lenti, Luca; López-Casado, Carlos; Martino, Salvatore; Peláez, José A.; Sanz de Galdeano, Carlos

    2015-04-01

    The reactivation of landslides is a major concern in regions of moderate to high seismicity, especially when it affects roads or villages. The Diezma landslide (Southern Spain), which had an estimated volume of 1.2 Mm3 and affected the main highway of Andalusia (A-92), it is located in a region of moderate seismicity and it has been active since 1998, but some local reactivations keep going after the general failure occurred in 2001, despite of the corrective measures built after the main failure. A heavy rain period was the triggering factor of the landslide, therefore future rains and mainly earthquakes may destabilize the whole slope again. An engineering-geological model of the landslide was developed from field surveys, laboratory tests, boreholes logs and geophysical investigations (MASW and seismic noise measurements). The landslide mass is constituted by silts and clays with heterometric blocks sliding on a metamorphic bedrock, and its mechanism was conditioned by structural constraints. The ground response o f the landslide was studied through experimental techniques including ambient noise and earthquake records. The ambient noise survey was designed for the use of the Nakamura's HVSR technique. While the measurements done inside the landslide exhibit a sharp peak whose peak frequency varies depending of the site within the landslide mass, those made outside landslide mass are characterized by a flat response. A temporary seismic network (0-30 s broadband seismometers), set up inside the landslide and in rocky outcrops outside the landslide, has allowed to record up to 20 earthquakes with epicentral distances from local to distant earthquakes, and magnitudes ranging from 1.7 to 7.2, showing similar spectral response to that retrieved from noise measurements. An unconventional pseudostatic analysis was applied to the landslide under limit equilibrium conditions through several sine waves, which cause accelerations which values are in the range of the

  15. Landslide Investigation by Repeat Airborne LiDAR and Ground Monitoring in the Western Suburb of Sapporo, Japan

    NASA Astrophysics Data System (ADS)

    Kasai, M.; Marutani, T.; Yoshida, H.

    2014-12-01

    This study presents landslide investigation using the combination of airborne LiDAR and ground monitoring data. The study site is located on the Teine Landslide (width: 2 km, Length: 6.5 km) in the western suburb of Sapporo city in Hokkaido Island, Japan, which collapsed more than 50,000 years ago. Since then streams have been developing and incising the landslide mass consisted of rock debris and volcanic deposits, presently causing a series of small deep-seated landslides along the banks. Because Sapporo is the economic center of Hokkaido and the suburb is expanding at the toe of the Teine slide, it is important to understand the behaviors of these active slopes to protect residents and infrastructures from unexpected disasters possibly triggered by an intense storm or earthquake. The LiDAR data for the area was first obtained by a manned helicopter in August 2010, and another survey by an unmanned helicopter is planned in autumn 2014 to estimate their activities from changes in the ground surfaces during the period from 2010 to 2014. Ground water level and landslide mass movements have also been monitored on site by using the coring holes for sampling since 2013. The combination of the data sets can make up the deficits of these methods, e.g., errors created through data processing for LiDAR survey and spatially limited information for ground monitoring, enabling to provide a solid three dimensional view of the slope movements. The notion obtained can be utilized to predict their future behaviors as well as to discover active but hiding landslides nearby. This study also showed that repeat monitoring of sites is a way of utilizing UAVs, particularly in terms of cost and convenience.

  16. [Spatial variability of surface soil nutrients in the landslide area of Beichuan County, South- west China, after 5 · 12 Wenchuan Earthquake].

    PubMed

    Mai, Ji-shan; Zhao, Ting-ning; Zheng, Jiang-kun; Shi, Chang-qing

    2015-12-01

    Based on grid sampling and laboratory analysis, spatial variability of surface soil nutrients was analyzed with GS⁺ and other statistics methods on the landslide area of Fenghuang Mountain, Leigu Town, Beichuan County. The results showed that except for high variability of available phosphorus, other soil nutrients exhibited moderate variability. The ratios of nugget to sill of the soil available phosphorus and soil organic carbon were 27.9% and 28.8%, respectively, showing moderate spatial correlation, while the ratios of nugget to sill of the total nitrogen (20.0%), total phosphorus (24.3%), total potassium (11.1%), available nitrogen (11.2%), and available potassium (22.7%) suggested strong spatial correlation. The total phosphorus had the maximum range (1232.7 m), followed by available nitrogen (541.27 m), total nitrogen (468.35 m), total potassium (136.0 m), available potassium (128.7 m), available phosphorus (116.6 m), and soil organic carbon (93.5 m). Soil nutrients had no significant variation with the increase of altitude, but gradually increased from the landslide area, the transition area, to the little-impacted area. The total and available phosphorus contents of the landslide area decreased by 10.3% and 79.7% compared to that of the little-impacted area, respectively. The soil nutrient contents in the transition area accounted for 31.1%-87.2% of that of the little-impacted area, with the nant reason for the spatial variability of surface soil nutrients.

  17. Ganges Landslide

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03681 Ganges Landslide

    Two large landslides dominate this image of part of Ganges Chasma. The eroded surface of an old landslide covers the north half of the image, while a more recent landslide occurs to the south.

    Image information: VIS instrument. Latitude -6.7N, Longitude 310.4E. 17 meter/pixel resolution.

    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.

    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.

  18. Issues and Advances in Understanding Landslide-Generated Tsunamis: Toward a Unified Model

    NASA Astrophysics Data System (ADS)

    Geist, E. L.; Locat, J.; Lee, H. J.; Lynett, P. J.; Parsons, T.; Kayen, R. E.; Hart, P. E.

    2008-12-01

    matrix affects the overall rheologic behavior during slide dynamics. For more rigid materials, such as carbonate and volcanic rocks, models are being developed that encompass the initial fracturing and eventual disintegration associated with debris avalanches. Lastly, the physics dictating the hydrodynamics of landslide-generated tsunamis is equally complex. The effects of non-linearity and dispersion are not necessarily negligible for landslides (in contrast to most earthquake-generated tsunamis), indicating that numerical implementation of the non-linear Boussinesq equations is often needed. Moreover, we show that for near-field landslide tsunamis propagating across the continental shelf, bottom friction (bottom boundary layer turbulence) and wave breaking can be important energy sinks. Detailed geophysical surveys can dissect landslide complexes to determine the geometry of individual events and help estimate rheological properties of the flowing mass, whereas cores in landslide provinces can determine the mechanical properties and pore-pressure distribution for pre- and post-failure sediment. This information is critical toward developing well-documented case histories for validating physics-based landslide tsunami models.

  19. Ground motions at the outermost limits of seismically triggered landslides

    Jibson, Randall W.; Harp, Edwin L.

    2016-01-01

    Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high‐resolution aerial‐photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (<1  m3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGAs) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02g to 0.08g. The range for the two earthquakes investigated using aerial‐photographic interpretations was 0.05–0.11g. Although PGA values at landslide limits depend on several factors, including material strength, topographic amplification, and hydrologic conditions, these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well‐recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground‐motion levels at the mapped limits.

  20. Ground motions at the outermost limits of seismically triggered landslides

    NASA Astrophysics Data System (ADS)

    Jibson, Randall W.; Harp, Edwin L.

    2016-04-01

    Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high-resolution aerial photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (< 1 m^3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGA) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02-0.08 g. The range for the two earthquakes investigated using aerial photographic interpretations was 0.05-0.11 g. Although PGA values at landslide limits depend on several factors - including material strength, topographic amplification, and hydrologic conditions - these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well-recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground-motion levels at the mapped limits.

  1. Earthquake classification, location, and error analysis in a volcanic environment: implications for the magmatic system of the 1989-1990 eruptions at redoubt volcano, Alaska

    Lahr, J.C.; Chouet, B.A.; Stephens, C.D.; Power, J.A.; Page, R.A.

    1994-01-01

    Determination of the precise locations of seismic events associated with the 1989-1990 eruptions of Redoubt Volcano posed a number of problems, including poorly known crustal velocities, a sparse station distribution, and an abundance of events with emergent phase onsets. In addition, the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm. This algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations. The velocity model was calibrated on the basis of a posteruptive seismic survey, in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice. The model consists of a stack of homogeneous horizontal layers; setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice. Detailed analysis of hypocentral errors shows that the long-period (LP) events constituting the vigorous 23-hour swarm that preceded the initial eruption on December 14 could have originated from a point 1.4 km below the crater floor. A similar analysis of LP events in the swarm preceding the major eruption on January 2 shows they also could have originated from a point, the location of which is shifted 0.8 km northwest and 0.7 km deeper than the source of the initial swarm. We suggest this shift in LP activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of December. Volcano-tectonic (VT) earthquakes did not occur until after the initial 23-hour-long swarm. They began slowly just below the LP source and their rate of occurrence increased after the eruption of 01:52 AST on December 15, when they shifted to depths of 6 to 10 km. After January 2 the VT activity migrated gradually northward; this migration suggests northward propagating withdrawal of

  2. Estimating the empirical probability of submarine landslide occurrence

    Geist, Eric L.; Parsons, Thomas E.; Mosher, David C.; Shipp, Craig; Moscardelli, Lorena; Chaytor, Jason D.; Baxter, Christopher D. P.; Lee, Homa J.; Urgeles, Roger

    2010-01-01

    The empirical probability for the occurrence of submarine landslides at a given location can be estimated from age dates of past landslides. In this study, tools developed to estimate earthquake probability from paleoseismic horizons are adapted to estimate submarine landslide probability. In both types of estimates, one has to account for the uncertainty associated with age-dating individual events as well as the open time intervals before and after the observed sequence of landslides. For observed sequences of submarine landslides, we typically only have the age date of the youngest event and possibly of a seismic horizon that lies below the oldest event in a landslide sequence. We use an empirical Bayes analysis based on the Poisson-Gamma conjugate prior model specifically applied to the landslide probability problem. This model assumes that landslide events as imaged in geophysical data are independent and occur in time according to a Poisson distribution characterized by a rate parameter λ. With this method, we are able to estimate the most likely value of λ and, importantly, the range of uncertainty in this estimate. Examples considered include landslide sequences observed in the Santa Barbara Channel, California, and in Port Valdez, Alaska. We confirm that given the uncertainties of age dating that landslide complexes can be treated as single events by performing statistical test of age dates representing the main failure episode of the Holocene Storegga landslide complex.

  3. Tithonium Landslide

    NASA Technical Reports Server (NTRS)

    2006-01-01

    12 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a large landslide deposit on the floor of western Tithonium Chasma.

    Location near: 4.3oS, 87.9oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

  4. Ophir Landslide

    NASA Technical Reports Server (NTRS)

    2005-01-01

    4 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small landslide off a steep slope in southwestern Ophir Chasma.

    Location near: 4.6oS, 72.8oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  5. Weights of Evidence Method for Landslide Susceptibility Mapping in Takengon, Central Aceh, Indonesia

    NASA Astrophysics Data System (ADS)

    Pamela; Sadisun, Imam A.; Arifianti, Yukni

    2018-02-01

    Takengon is an area prone to earthquake disaster and landslide. On July 2, 2013, Central Aceh earthquake induced large numbers of landslides in Takengon area, which resulted in casualties of 39 people. This location was chosen to assess the landslide susceptibility of Takengon, using a statistical method, referred to as the weight of evidence (WoE). This WoE model was applied to indicate the main factors influencing the landslide susceptible area and to derive landslide susceptibility map of Takengon. The 251 landslides randomly divided into two groups of modeling/training data (70%) and validation/test data sets (30%). Twelve thematic maps of evidence are slope degree, slope aspect, lithology, land cover, elevation, rainfall, lineament, peak ground acceleration, curvature, flow direction, distance to river and roads used as landslide causative factors. According to the AUC, the significant factor controlling the landslide is the slope, the slope aspect, peak ground acceleration, elevation, lithology, flow direction, lineament, and rainfall respectively. Analytical result verified by using test data of landslide shows AUC prediction rate is 0.819 and AUC success rate with all landslide data included is 0.879. This result showed the selective factors and WoE method as good models for assessing landslide susceptibility. The landslide susceptibility map of Takengon shows the probabilities, which represent relative degrees of susceptibility for landslide proneness in Takengon area.

  6. Fostering the uptake of satellite Earth Observation data for landslide hazard understanding: the CEOS Landslide Pilot

    NASA Astrophysics Data System (ADS)

    Kirschbaum, Dalia; Malet, Jean-Philippe; Roessner, Sigrid

    2017-04-01

    Landslides occur around the world, on every continent, and play an important role in the evolution of landscapes. They also represent a serious hazard in many areas of the world. Despite their importance, it has been estimated that past landslide and landslide potential maps cover less than 1% of the slopes in these landmasses. Systematic information on the type, abundance, and distribution of existing landslides is lacking. Even in countries where landslide information is abundant (e.g. Italy), the vast majority of landslides caused by meteorological (intense or prolonged rainfall, rapid snowmelt) or geophysical (earthquake) triggers go undetected. This paucity of knowledge has consequences on the design of effective remedial and mitigation measures. Systematic use of Earth observation (EO) data and technologies can contribute effectively to detect, map, and monitor landslides, and landslide prone hillsides, in different physiographic and climatic regions. The CEOS (Committee on Earth Observation Satellites) Working Group on Disasters has recently launched a Landslide Pilot (period 2017-2019) with the aim to demonstrate the effective exploitation of satellite EO across the full cycle of landslide disaster risk management, including preparedness, response, and recovery at global, regional, and local scales, with a distinct multi-hazard focus on cascading impacts and risks. The Landslide Pilot is focusing efforts on three objectives: 1. Establish effective practices for merging different Earth Observation data (e.g. optical and radar) to better monitor and map landslide activity over time and space. 2. Demonstrate how landslide products, models, and services can support disaster risk management for multi-hazard and cascading landslide events. 3. Engage and partner with data brokers and end users to understand requirements and user expectations and get feedback through the activities described in objectives 1-2. The Landslide Pilot was endorsed in April 2016 and work

  7. Rainfall-induced landslides in Puerto Rico: An overview

    Pando, M.A.; Ruiz, M.E.; Larsen, M.C.

    2005-01-01

    Rainfall-induced landslides are common in Puerto Rico (PR). The presence of steep slopes in mountainous terrain, coupled with weathered soils and intense rainfall, leads to severe slope-stability problems throughout the island. Episodic triggering events such as hurricanes and earthquakes further exacerbate these problems. All physiographic provinces of the island have experienced landslides. The stability of natural and man-made slopes is a serious concern for government authorities and the civil engineering community in Puerto Rico. This paper presents an overview of the rainfall induced landslide problem in PR, a summary of literature published on this subject, and proposes a rainfall intensity landslide threshold based on landslide events data from 1959 to 2003. This threshold can be used as part of a potential landslide warning system.

  8. Fluid-Faulting Interactions Examined Though Massive Waveform-Based Analyses of Earthquake Swarms in Volcanic and Tectonic Settings: Mammoth Mountain, Long Valley, Lassen, and Fillmore, California Swarms, 2014-2015

    NASA Astrophysics Data System (ADS)

    Shelly, D. R.; Ellsworth, W. L.; Prejean, S. G.; Hill, D. P.; Hardebeck, J.; Hsieh, P. A.

    2015-12-01

    Earthquake swarms, sequences of sustained seismicity, convey active subsurface processes that sometimes precede larger tectonic or volcanic episodes. Their extended activity and spatiotemporal migration can often be attributed to fluid pressure transients as migrating crustal fluids (typically water and CO2) interact with subsurface structures. Although the swarms analyzed here are interpreted to be natural in origin, the mechanisms of seismic activation likely mirror those observed for earthquakes induced by industrial fluid injection. Here, we use massive-scale waveform correlation to detect and precisely locate 3-10 times as many earthquakes as included in routine catalogs for recent (2014-2015) swarms beneath Mammoth Mountain, Long Valley Caldera, Lassen Volcanic Center, and Fillmore areas of California, USA. These enhanced catalogs, with location precision as good as a few meters, reveal signatures of fluid-faulting interactions, such as systematic migration, fault-valve behavior, and fracture mesh structures, not resolved in routine catalogs. We extend this analysis to characterize source mechanism similarity even for very small newly detected events using relative P and S polarity estimates. This information complements precise locations to define fault complexities that would otherwise be invisible. In particular, although swarms often consist of groups of highly similar events, some swarms contain a population of outliers with different slip and/or fault orientations. These events highlight the complexity of fluid-faulting interactions. Despite their different settings, the four swarms analyzed here share many similarities, including pronounced hypocenter migration suggestive of a fluid pressure trigger. This includes the July 2015 Fillmore swarm, which, unlike the others, occurred outside of an obvious volcanic zone. Nevertheless, it exhibited systematic westward and downdip migration on a ~1x1.5 km low-angle, NW-dipping reverse fault at midcrustal depth.

  9. A new concept in seismic landslide hazard analysis for practical application

    NASA Astrophysics Data System (ADS)

    Lee, Chyi-Tyi

    2017-04-01

    A seismic landslide hazard model could be constructed using deterministic approach (Jibson et al., 2000) or statistical approach (Lee, 2014). Both approaches got landslide spatial probability under a certain return-period earthquake. In the statistical approach, our recent study found that there are common patterns among different landslide susceptibility models of the same region. The common susceptibility could reflect relative stability of slopes at a region; higher susceptibility indicates lower stability. Using the common susceptibility together with an earthquake event landslide inventory and a map of topographically corrected Arias intensity, we can build the relationship among probability of failure, Arias intensity and the susceptibility. This relationship can immediately be used to construct a seismic landslide hazard map for the region that the empirical relationship built. If the common susceptibility model is further normalized and the empirical relationship built with normalized susceptibility, then the empirical relationship may be practically applied to different region with similar tectonic environments and climate conditions. This could be feasible, when a region has no existing earthquake-induce landslide data to train the susceptibility model and to build the relationship. It is worth mentioning that a rain-induced landslide susceptibility model has common pattern similar to earthquake-induced landslide susceptibility in the same region, and is usable to build the relationship with an earthquake event landslide inventory and a map of Arias intensity. These will be introduced with examples in the meeting.

  10. Landslides in everyday life: An interdisciplinary approach to understanding vulnerability in the Himalayas

    NASA Astrophysics Data System (ADS)

    Sudmeier-Rieux, K.; Breguet, A.; Dubois, J.; Jaboyedoff, M.

    2009-04-01

    Several thousand landslides were triggered by the Kashmir earthquake, scarring the hillside with cracks. Monsoon rains continue to trigger landslides, which have increased the exposure of populations because of lost agricultural lands, blocked roads and annual fatalities due to landslides. The great majority of these landslides are shallow and relatively small but greatly impacting the population. In this region, landslides were a factor before the earthquake, mainly due to road construction and gravel excavation, but the several thousand landslides triggered by the earthquake have completely overwhelmed the local population and authorities. In Eastern Nepal, the last large earthquake to hit this region occurred in 1988, also triggering numerous landslides and cracks. Here, landslides can be considered a more common phenomenon, yet coping capacities amount to local observations of landslide movement, subsequent abandonment of houses and land as they become too dangerous. We present a comparative case study from Kashmir, Pakistan and Eastern Nepal, highlighting an interdisciplinary approach to understanding the complex interactions between land use, landslides and vulnerability. Our approach sets out to understand underlying causes of the massive landslides triggered by the 2005 earthquake in Kashmir, Pakistan, and also the increasing number of landslides in Nepal. By approaching the issue of landslides from multiple angles (risk perceptions, land use, local coping capacities, geological assessment, risk mapping) and multiple research techniques (remote sensing, GIS, geological assessment, participatory mapping, focus groups) we are better able to create a more complete picture of the "hazardscape". We find that by combining participatory social science research with hazard mapping, we obtain a more complete understanding of underlying causes, coping strategies and possible mitigation options, placing natural hazards in the context of everyday life. This method is

  11. Deviation from Power Law Behavior in Landslide Phenomenon

    NASA Astrophysics Data System (ADS)

    Li, L.; Lan, H.; Wu, Y.

    2013-12-01

    Power law distribution of magnitude is widely observed in many natural hazards (e.g., earthquake, floods, tornadoes, and forest fires). Landslide is unique as the size distribution of landslide is characterized by a power law decrease with a rollover in the small size end. Yet, the emergence of the rollover, i.e., the deviation from power law behavior for small size landslides, remains a mystery. In this contribution, we grouped the forces applied on landslide bodies into two categories: 1) the forces proportional to the volume of failure mass (gravity and friction), and 2) the forces proportional to the area of failure surface (cohesion). Failure occurs when the forces proportional to volume exceed the forces proportional to surface area. As such, given a certain mechanical configuration, the failure volume to failure surface area ratio must exceed a corresponding threshold to guarantee a failure. Assuming all landslides share a uniform shape, which means the volume to surface area ratio of landslide regularly increase with the landslide volume, a cutoff of landslide volume distribution in the small size end can be defined. However, in realistic landslide phenomena, where heterogeneities of landslide shape and mechanical configuration are existent, a simple cutoff of landslide volume distribution does not exist. The stochasticity of landslide shape introduce a probability distribution of the volume to surface area ratio with regard to landslide volume, with which the probability that the volume to surface ratio exceed the threshold can be estimated regarding values of landslide volume. An experiment based on empirical data showed that this probability can induce the power law distribution of landslide volume roll down in the small size end. We therefore proposed that the constraints on the failure volume to failure surface area ratio together with the heterogeneity of landslide geometry and mechanical configuration attribute for the deviation from power law

  12. Earthquakes drive focused denudation along a tectonically active mountain front

    NASA Astrophysics Data System (ADS)

    Li, Gen; West, A. Joshua; Densmore, Alexander L.; Jin, Zhangdong; Zhang, Fei; Wang, Jin; Clark, Marin; Hilton, Robert G.

    2017-08-01

    Earthquakes cause widespread landslides that can increase erosional fluxes observed over years to decades. However, the impact of earthquakes on denudation over the longer timescales relevant to orogenic evolution remains elusive. Here we assess erosion associated with earthquake-triggered landslides in the Longmen Shan range at the eastern margin of the Tibetan Plateau. We use the Mw 7.9 2008 Wenchuan and Mw 6.6 2013 Lushan earthquakes to evaluate how seismicity contributes to the erosional budget from short timescales (annual to decadal, as recorded by sediment fluxes) to long timescales (kyr to Myr, from cosmogenic nuclides and low temperature thermochronology). Over this wide range of timescales, the highest rates of denudation in the Longmen Shan coincide spatially with the region of most intense landsliding during the Wenchuan earthquake. Across sixteen gauged river catchments, sediment flux-derived denudation rates following the Wenchuan earthquake are closely correlated with seismic ground motion and the associated volume of Wenchuan-triggered landslides (r2 > 0.6), and to a lesser extent with the frequency of high intensity runoff events (r2 = 0.36). To assess whether earthquake-induced landsliding can contribute importantly to denudation over longer timescales, we model the total volume of landslides triggered by earthquakes of various magnitudes over multiple earthquake cycles. We combine models that predict the volumes of landslides triggered by earthquakes, calibrated against the Wenchuan and Lushan events, with an earthquake magnitude-frequency distribution. The long-term, landslide-sustained "seismic erosion rate" is similar in magnitude to regional long-term denudation rates (∼0.5-1 mm yr-1). The similar magnitude and spatial coincidence suggest that earthquake-triggered landslides are a primary mechanism of long-term denudation in the frontal Longmen Shan. We propose that the location and intensity of seismogenic faulting can contribute to

  13. Ganges Landslides

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This Mars Global Surveyor (MGS) Orbiter Camera (MOC) image shows a high resolution view of portions of the lobes of several landslide deposits in Ganges Chasma. Dark material near the bottom (south) end of the image is windblown sand.

    Location near: 8.2oS, 44.3oW Image width: 3.0 km (1.9 mi) Illumination from: upper left Season: Southern Winter

  14. Geomodels of coseismic landslides environments in Central Chile.

    NASA Astrophysics Data System (ADS)

    Serey, A.; Sepulveda, S. A.; Murphy, W.; Petley, D. N.

    2017-12-01

    Landslides are a major source of fatalities and damage during strong earthquakes in mountain areas. Detailed geomodels of coseismic landslides environments are essential parts of seismic landslide hazard analyses. The development of a site specific geological model is required, based on consideration of the regional and local geological and geomorphological history and the current ground surface conditions. An engineering geological model is any approximation of the geological conditions, at varying scales, created for the purpose of solving an engineering problem. In our case, the objective is the development of a methodology for earthquake-induced landslide hazard assessment applicable to urban/territorial planning and disaster prevention strategies assessment at a regional scale adapted for the Chilean tectonic conditions. We have developed the only 2 complete inventories of landslides triggered by earthquakes in Chile. The first from the Mw 6.2, shallow crustal Aysén earthquake in 2007. Second one from the Mw 8.8, megathrust subduction Maule earthquake in 2010. From the comparison of these 2 inventories with others from abroad, as well as analysis of large, prehistoric landslide inventories proposed as likely induced by seismic activity we have determined topographic, geomorphological, geological and seismic controlling factors in the occurrence of earthquake-triggered landslides. With the information collected we have defined different environments for generation of coseismic landslides based on the construction of geomodels. As a result we have built several geomodels in the Santiago Cordillera in central Chile (33°S), based upon the San Ramón Fault, a west-vergent reverse fault that outcrops at the edge of Santiago basin recently found to be active and a likely source of seismic activity in the future, with potential of triggering landslides in the Santiago mountain front as well as inland into the Mapocho and Maipo Cordilleran valleys. In conclusion

  15. Submarine landslides of the Southern California Borderland

    Lee, H.J.; Greene, H. Gary; Edwards, B.D.; Fisher, M.A.; Normark, W.R.

    2009-01-01

    Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ??2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the mainland slope- Goleta slide in Santa Barbara Channel and Palos Verdes debris avalanche on the San Pedro Escarpment south of Palos Verdes Peninsula. Both of these complexes indicate repeated recurrences of catastrophic slope failure. Recurrence intervals are not well constrained but appear to be in the range of 7500 years for the Goleta slide. The most recent major activity of the Palos Verdes debris avalanche occurred roughly 7500 years ago. A small failure deposit in Santa Barbara Channel, the Gaviota mudflow, was perhaps caused by an 1812 earthquake. Most landslides in this region are probably triggered by earthquakes, although the larger failures were likely conditioned by other factors, such as oversteepening, development of shelf-edge deltas, and high fluid pressures. If a subsequent future landslide were to occur in the area of these large landslide complexes, a tsunami would probably result. Runup distances of 10 m over a 30-km-long stretch of the Santa Barbara coastline are predicted for a recurrence of the Goleta slide, and a runup of 3 m over a comparable stretch of the Los Angeles coastline is modeled for the Palos Verdes debris avalanche. ?? 2009 The Geological Society of America.

  16. Crater Landslide

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA06088 Crater Landslide

    This landslide occurs in an unnamed crater southeast of Millochau Crater.

    Image information: VIS instrument. Latitude -24.4N, Longitude 87.5E. 17 meter/pixel resolution.

    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.

    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.

  17. Submarine Landslides at Santa Catalina Island, California

    NASA Astrophysics Data System (ADS)

    Legg, M. R.; Francis, R. D.

    2011-12-01

    Santa Catalina Island is an active tectonic block of volcanic and metamorphic rocks originally exposed during middle Miocene transtension along the evolving Pacific-North America transform plate boundary. Post-Miocene transpression created the existing large pop-up structure along the major strike-slip restraining bend of the Catalina fault that forms the southwest flank of the uplift. Prominent submerged marine terraces apparent in high-resolution bathymetric maps interrupt the steep submarine slopes in the upper ~400 meters subsea depths. Steep subaerial slopes of the island are covered by Quaternary landslides, especially at the sea cliffs and in the blueschist metamorphic rocks. The submarine slopes also show numerous landslides that range in area from a few hectares to more than three sq-km (300 hectares). Three or more landslides of recent origin exist between the nearshore and first submerged terrace along the north-facing shelf of the island's West End. One of these slides occurred during September 2005 when divers observed a remarkable change in the seafloor configuration after previous dives in the area. Near a sunken yacht at about 45-ft depth where the bottom had sloped gently into deeper water, a "sinkhole" had formed that dropped steeply to 100-ft or greater depths. Some bubbling sand was observed in the shallow water areas that may be related to the landslide process. High-resolution multibeam bathymetry acquired in 2008 by CSU Monterey Bay show this "fresh" slide and at least two other slides of varying age along the West End. The slides are each roughly 2 hectares in area and their debris aprons are spread across the first terrace at about 85-m water depth that is likely associated with the Last Glacial Maximum sealevel lowstand. Larger submarine slides exist along the steep Catalina and Catalina Ridge escarpments along the southwest flank of the island platform. A prominent slide block, exceeding 3 sq-km in area, appears to have slipped more than

  18. Anaglyph, Lake Palanskoye Landslide, Kamchatka Peninsula, Russia

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Lake Palanskoye in northern Kamchatka was formed when a large landslide disrupted the drainage pattern, forming a natural dam. The area is volcanically and tectonically active and it is likely that the landslide -- which covers about 80 square kilometers (30 square miles) --was triggered by an earthquake sometime in the past 10,000 years. The source area of the landslide is the ridge to the upper left of the lake. The steep topographic scar at the head of the slide and the broad expanse of hummocky landslide debris that covers the valley to the left of the lake are visible in 3D.

    This anaglyph was generated by first draping a Landsat Thematic Mapper near-infrared image over a topographic map from the Shuttle Radar Topography Mission, then using the topographic data to create two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30 meter (99 foot) spatial resolution of most Landsat images and will provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center, Sioux Falls, South Dakota.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface on its 11-day mission. To collect the 3-D data, engineers added a 60-meter

  19. The Volcanic Story of the Columbia River Gorge.

    ERIC Educational Resources Information Center

    Allen, John Eliot

    1982-01-01

    Uses maps, diagrams, and geological accounts to describe the Columbia River Gorge which separates Oregon from Washington and exposes an unexcelled record of Cenozoic volcanic stratigraphy, sedimentation, flooding, and landsliding for the visiting tourists, geologists, or students. (Author/DC)

  20. Geotechnical aspects of the 2016 MW 6.2, MW 6.0, and MW 7.0 Kumamoto earthquakes

    Kayen, Robert E.; Dashti, Shideh; Kokusho, T.; Hazarika, H.; Franke, Kevin; Oettle, N. K.; Wham, Brad; Ramirez Calderon, Jenny; Briggs, Dallin; Guillies, Samantha; Cheng, Katherine; Tanoue, Yutaka; Takematsu, Katsuji; Matsumoto, Daisuke; Morinaga, Takayuki; Furuichi, Hideo; Kitano, Yuuta; Tajiri, Masanori; Chaudhary, Babloo; Nishimura, Kengo; Chu, Chu

    2017-01-01

    The 2016 Kumamoto earthquakes are a series of events that began with an earthquake of moment magnitude 6.2 on the Hinagu Fault on April 14, 2016, followed by another foreshock of moment magnitude 6.0 on the Hinagu Fault on April 15, 2016, and a larger moment magnitude 7.0 event on the Futagawa Fault on April 16, 2016 beneath Kumamoto City, Kumamoto Prefecture on Kyushu, Japan. These events are the strongest earthquakes recorded in Kyushu during the modern instrumental era. The earthquakes resulted in substantial damage to infrastructure, buildings, cultural heritage of Kumamoto Castle, roads and highways, slopes, and river embankments due to earthquake-induced landsliding and debris flows. Surface fault rupture produced offset and damage to roads, buildings, river levees, and an agricultural dam. Surprisingly, given the extremely intense earthquake motions, liquefaction occurred only in a few districts of Kumamoto City and in the port areas indicating that the volcanic soils were less susceptible to liquefying than expected given the intensity of earthquake shaking, a significant finding from this event.

  1. Landslide Hazards in the Seattle, Washington, Area

    Baum, Rex; Harp, Ed; Highland, Lynn

    2007-01-01

    The Seattle, Washington, area is known for its livability and its magnificent natural setting. The city and nearby communities are surrounded by an abundance of rivers and lakes and by the bays of Puget Sound. Two majestic mountain ranges, the Olympics and the Cascades, rim the region. These dramatic natural features are products of dynamic forces-landslides, earthquakes, tsunamis, glaciers, volcanoes, and floods. The same processes that formed this beautiful landscape pose hazards to the ever-growing population of the region. Landslides long have been a major cause of damage and destruction to people and property in the Seattle area.

  2. New Field Observations About 19 August 1966 Varto earthquake, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Gurboga, S.

    2013-12-01

    a) source of 1966 earthquake is Varto segment in Varto Fault Zone, b) many of the surface deformations observed just after the earthquake is lateral-spreading and small landslides, c) surface rupture was created with 10 cm displacement at the surface with thrust component. Because of the volcanic cover and activation of many faults, ground surface rupture could not be seen clearly which has been expected after 6.8 magnitude earthquake, d) faulting type is right-lateral component with thrust component. Keywords: 1966 Varto earthquake, paleoseismology, right-lateral fault with thrust component.

  3. Combine bivariate statistics analysis and multivariate statistics analysis to assess landslide susceptibility in Chen-Yu-Lan watershed, Nantou, Taiwan.

    NASA Astrophysics Data System (ADS)

    Ngan Nguyen, Thi To; Liu, Cheng-Chien

    2013-04-01

    How landslides occurred and which factors triggered and sped up landslide occurrences were usually asked by researchers in the past decades. Many investigations carried out in many places in the world to finding out methods that predict and prevent damages from landslides phenomena. Chen-Yu-Lan River watershed is reputed as a 'hot pot' of landslide researches in Taiwan by its complicated geological structures with the significant tectonic fault systems and steeply mountainous terrain. Beside annual high precipitation concentration and the abrupt slopes, some natural disaster, as typhoons (Sinlaku-2008, Kalmaegi-2008, and Marakot-2009) and earthquake (Chi-Chi earthquake-1999) are also the triggered factors cause landslides with serious damages in this place. This research expresses the quantitative approaches to generate landslide susceptible map for Chen-Yu-Lan watershed, a mountainous area in the central Taiwan. Landslide inventories data, which were detected from the Formosat-2 imageries for eight years from 2004 to 2011, were applied to carry out landslide susceptibility mapping. Bivariate statistics analysis and multivariate statistics analysis would be applied to calculate susceptible index of landslides. The weights of parameters were computed based on landslide data for eight years from 2004 to 2011. To validate effective levels of factors to landslide occurrences, this method built some multivariate algorithms and compared these results with real landslide occurrences. Besides this method, the historical data of landslides were also used to assess and classify landslide susceptibility levels. From long-term landslide data, relation between landslide susceptibility levels and landslide repetition was assigned. The results demonstrated differently effective levels of potential factors, such as, slope gradient, drainage density, lithology and land use to landslide phenomena. The results also showed logical relationship between weights and characteristics of

  4. Spatial and temporal variation of seismic velocity during earthquakes and volcanic eruptions in western Japan: Insight into mechanism for seismic velocity variation

    NASA Astrophysics Data System (ADS)

    Tsuji, T.; Ikeda, T.; Nimiya, H.

    2017-12-01

    We report spatio-temporal variations of seismic velocity around the seismogenic faults in western Japan. We mainly focus on the seismic velocity variation during (1) the 2016 Off-Mie earthquake in the Nankai subduction zone (Mw5.8) and (2) the 2016 Kumamoto earthquake in Kyushu Island (Mw7.0). We applied seismic interferometry and surface wave analysis to the ambient noise data recorded by Hi-net and DONET seismometers of National Research Institute for Earth Science and Disaster Resilience (NIED). Seismic velocity near the rupture faults and volcano decreased during the earthquake. For example, we observed velocity reduction around the seismogenic Futagawa-Hinagu fault system and Mt Aso in the 2016 Kumamoto earthquake. We also identified velocity increase after the eruptions of Mt Aso. During the 2016 Off-Mie earthquake, we observed seismic velocity variation in the Nankai accretionary prism. After the earthquakes, the seismic velocity gradually returned to the pre-earthquake value. The velocity recovering process (healing process) is caused by several mechanisms, such as pore pressure reduction, strain change, and crack sealing. By showing the velocity variations obtained at different geologic settings (volcano, seismogenic fault, unconsolidated sediment), we discuss the mechanism of seismic velocity variation as well as the post-seismic fault healing process.

  5. Coulomb Mechanics And Landscape Geometry Explain Landslide Size Distribution

    NASA Astrophysics Data System (ADS)

    Jeandet, L.; Steer, P.; Lague, D.; Davy, P.

    2017-12-01

    It is generally observed that the dimensions of large bedrock landslides follow power-law scaling relationships. In particular, the non-cumulative frequency distribution (PDF) of bedrock landslide area is well characterized by a negative power-law above a critical size, with an exponent 2.4. However, the respective role of bedrock mechanical properties, landscape shape and triggering mechanisms on the scaling properties of landslide dimensions are still poorly understood. Yet, unravelling the factors that control this distribution is required to better estimate the total volume of landslides triggered by large earthquakes or storms. To tackle this issue, we develop a simple probabilistic 1D approach to compute the PDF of rupture depths in a given landscape. The model is applied to randomly sampled points along hillslopes of studied digital elevation models. At each point location, the model determines the range of depth and angle leading to unstable rupture planes, by applying a simple Mohr-Coulomb rupture criterion only to the rupture planes that intersect downhill surface topography. This model therefore accounts for both rock mechanical properties, friction and cohesion, and landscape shape. We show that this model leads to realistic landslide depth distribution, with a power-law arising when the number of samples is high enough. The modeled PDF of landslide size obtained for several landscapes match the ones from earthquakes-driven landslides catalogues for the same landscape. In turn, this allows us to invert landslide effective mechanical parameters, friction and cohesion, associated to those specific events, including Chi-Chi, Wenchuan, Niigata and Gorkha earthquakes. The cohesion and friction ranges (25-35 degrees and 5-20 kPa) are in good agreement with previously inverted values. Our results demonstrate that reduced complexity mechanics is efficient to model the distribution of unstable depths, and show the role of landscape variability in landslide size

  6. Education for Earthquake Disaster Prevention in the Tokyo Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Oki, S.; Tsuji, H.; Koketsu, K.; Yazaki, Y.

    2008-12-01

    Japan frequently suffers from all types of disasters such as earthquakes, typhoons, floods, volcanic eruptions, and landslides. In the first half of this year, we already had three big earthquakes and heavy rainfall, which killed more than 30 people. This is not just for Japan but Asia is the most disaster-afflicted region in the world, accounting for about 90% of all those affected by disasters, and more than 50% of the total fatalities and economic losses. One of the most essential ways to reduce the damage of natural disasters is to educate the general public to let them understand what is going on during those desasters. This leads individual to make the sound decision on what to do to prevent or reduce the damage. The Ministry of Education, Culture, Sports, Science and Technology (MEXT), therefore, offered for public subscription to choose several model areas to adopt scientific education to the local elementary schools, and ERI, the Earthquake Research Institute, is qualified to develop education for earthquake disaster prevention in the Tokyo metropolitan area. The tectonic setting of this area is very complicated; there are the Pacific and Philippine Sea plates subducting beneath the North America and the Eurasia plates. The subduction of the Philippine Sea plate causes mega-thrust earthquakes such as the 1703 Genroku earthquake (M 8.0) and the 1923 Kanto earthquake (M 7.9) which had 105,000 fatalities. A magnitude 7 or greater earthquake beneath this area is recently evaluated to occur with a probability of 70 % in 30 years. This is of immediate concern for the devastating loss of life and property because the Tokyo urban region now has a population of 42 million and is the center of approximately 40 % of the nation's activities, which may cause great global economic repercussion. To better understand earthquakes in this region, "Special Project for Earthquake Disaster Mitigation in Tokyo Metropolitan Area" has been conducted mainly by ERI. It is a 4-year

  7. Size distributions and failure initiation of submarine and subaerial landslides

    ten Brink, Uri S.; Barkan, R.; Andrews, B.D.; Chaytor, J.D.

    2009-01-01

    Landslides are often viewed together with other natural hazards, such as earthquakes and fires, as phenomena whose size distribution obeys an inverse power law. Inverse power law distributions are the result of additive avalanche processes, in which the final size cannot be predicted at the onset of the disturbance. Volume and area distributions of submarine landslides along the U.S. Atlantic continental slope follow a lognormal distribution and not an inverse power law. Using Monte Carlo simulations, we generated area distributions of submarine landslides that show a characteristic size and with few smaller and larger areas, which can be described well by a lognormal distribution. To generate these distributions we assumed that the area of slope failure depends on earthquake magnitude, i.e., that failure occurs simultaneously over the area affected by horizontal ground shaking, and does not cascade from nucleating points. Furthermore, the downslope movement of displaced sediments does not entrain significant amounts of additional material. Our simulations fit well the area distribution of landslide sources along the Atlantic continental margin, if we assume that the slope has been subjected to earthquakes of magnitude ??? 6.3. Regions of submarine landslides, whose area distributions obey inverse power laws, may be controlled by different generation mechanisms, such as the gradual development of fractures in the headwalls of cliffs. The observation of a large number of small subaerial landslides being triggered by a single earthquake is also compatible with the hypothesis that failure occurs simultaneously in many locations within the area affected by ground shaking. Unlike submarine landslides, which are found on large uniformly-dipping slopes, a single large landslide scarp cannot form on land because of the heterogeneous morphology and short slope distances of tectonically-active subaerial regions. However, for a given earthquake magnitude, the total area

  8. Ganges Chasma Landslide

    2002-05-21

    This image from NASA Mars Odyssey spacecraft shows a spectacular landslide along a portion of the southern wall of Ganges Chasma within Valles Marineris. Landslides have very characteristic morphologies on Earth, which they also display on Mars.

  9. New Insights on co-seismic landslide clustering

    NASA Astrophysics Data System (ADS)

    Meunier, Patrick; Marc, Odin; Hovius, Niels

    2015-04-01

    Earthquake-triggered landslides tend to cluster along topographic crests while rainfall-induced landslides should occur downslope preferentially, where pore pressure induced by groundwater flows is the highest [1]. Past studies on landslide clustering are all based on the analysis of complete dataset or subdataset of landslides associated with a given event (seismic or climatic) as a whole. In this work, we document the spatial and temporal variations of the landslide position (on hillslopes) within the epicentral area of the 1994 Northridge, the 1999 Chichi, the 2004 Niigata, the 2008 Iwate and the 2008 Wenchuan earthquakes. We show that crest clustering is not systematic, non uniform in space and exhibit patterns that vary a lot from one case to another. These patterns are not easy to interpret as they don't seem to be controlled by a single governing parameter but result from a complex interaction between local (hillslope length and gradient, lithology) and seismic (distance to source, slope aspect, radiation pattern, coseismic uplift) parameters. [1] Meunier, P., Hovius, N., & Haines, J. A. (2008). Topographic site effects and the location of earthquake induced landslides. Earth and Planetary Science Letters, 275(3), 221-232

  10. Landslide-Generated Waves in a Dam Reservoir: The Effects of Landslide Rheology and Initial Submergence

    NASA Astrophysics Data System (ADS)

    Yavari Ramsheh, S.; Ataie-Ashtiani, B.

    2017-12-01

    Recent studies revealed that landslide-generated waves (LGWs) impose the largest tsunami hazard to our shorelines although earthquake-generated waves (EGWs) occur more often. Also, EGWs are commonly followed by a large number of landslide hazards. Dam reservoirs are more vulnerable to landslide events due to being located in mountainous areas. Accurate estimation of such hazards and their destructive consequences help authorities to reduce their risks by constructive measures. In this regard, a two-layer two-phase Coulomb mixture flow (2LCMFlow) model is applied to investigate the effects of landslide characteristics on LGWs for a real-sized simplification of the Maku dam reservoir, located in the North of Iran. A sensitivity analysis is performed on the role of landslide rheological and constitutive parameters and its initial submergence in LGW characteristics and formation patterns. The numerical results show that for a subaerial (SAL), a semi-submerged (SSL), and a submarine landslide (SML) with the same initial geometry, the SSLs can create the largest wave crest, up to 60% larger than SALs, for dense material. However, SMLs generally create the largest wave troughs and SALs travel the maximum runout distances beneath the water. Regarding the two-phase (solid-liquid) nature of the landslide, when interestial water is isolated from the water layer along the water/landslide interface, a LGW with up to 30% higher wave crest can be created. In this condition, increasing the pore water pressure within the granular layer results in up to 35% higher wave trough and 40% lower wave crest at the same time. These results signify the importance of appropriate description of two-phase nature and rheological behavior of landslides in accurate estimation of LGWs which demands further numerical, physical, and field studies about such phenomena.

  11. Landslide characteristics and spatial distribution in the Rwenzori Mountains, Uganda

    NASA Astrophysics Data System (ADS)

    Jacobs, Liesbet; Dewitte, Olivier; Poesen, Jean; Maes, Jan; Mertens, Kewan; Sekajugo, John; Kervyn, Matthieu

    2017-10-01

    In many landslide-prone regions, data on landslide characteristics remain poor or inexistent. This is also the case for the Rwenzori Mountains, located on the border of Uganda and the DR Congo. There, landslides frequently occur and cause fatalities and substantial damage to private property and infrastructure. In this paper, we present the results of a field inventory performed in three representative study areas covering 114 km2. A total of 371 landslides were mapped and analyzed for their geomorphological characteristics and their spatial distribution. The average landslide areas varied from less than 0.3 ha in the gneiss-dominated highlands to >1 ha in the rift alluvium of the lowlands. Large landslides (>1.5 ha) are well represented while smaller landslides (<1.5 ha) are underrepresented. The degrees of completeness of the field inventories are comparable to those of similar historical landslide inventories. The diversity of potential mass movements in the Rwenzori is large and depends on the dominant lithological and topographic conditions. A dominance of shallow translational soil slides in gneiss and of deep rotational soil slides in the rift alluvium is observed. Slope angle is the main controlling topographic factor for landslides with the highest landslide concentrations for slope angles above 25-30° in the highlands and 10-15° in the lowlands. The undercutting of slopes by rivers and excavations for construction are important preparatory factors. Rainfall-triggered landslides are the most common in the area, however in the zones of influence of the last two major earthquakes (1966: Mw = 6.6 and 1994: Mw = 6.2), 12 co-seismic landslides were also observed.

  12. Venus - Volcano With Massive Landslides

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This Magellan full-resolution mosaic which covers an area 143 by 146 kilometers (89 by 91 miles) is centered at 55 degrees north latitude, 266 degrees east longitude. The bright feature, slightly south of center is interpreted to be a volcano, 15-20 kilometers (9.3 to 12.4 miles) in diameter with a large apron of blocky debris to its right and some smaller aprons to its left. A preferred explanation is that several massive catastrophic landslides dropped down steep slopes and were carried by their momentum out into the smooth, dark lava plains. At the base of the east-facing or largest scallop on the volcano is what appears to be a large block of coherent rock, 8 to 10 kilometers (5 to 6 miles) in length. The similar margin of both the scallop and block and the shape in general is typical of terrestrial slumped blocks (masses of rock which slide and rotate down a slope instead of breaking apart and tumbling). The bright lobe to the south of the volcano may either be a lava flow or finer debris from other landslides. This volcanic feature, characterized by its scalloped flanks is part of a class of volcanoes called scalloped or collapsed domes of which there are more than 80 on Venus. Based on the chute-like shapes of the scallops and the existence of a spectrum of intermediate to well defined examples, it is hypothesized that all of the scallops are remnants of landslides even though the landslide debris is often not visible. Possible explanations for the missing debris are that it may have been covered by lava flows, the debris may have weathered or that the radar may not be recognizing it because the individual blocks are too small

  13. Landslides and Mudslides

    MedlinePlus

    ... from landslides and debris flows In the United States, landslides and debris flows result in 25 to 50 deaths each year. ... and debris flows. Learn whether landslides or debris flows have ... department, state geological surveys or departments of natural resources, or ...

  14. On the behavior of site effects in central Mexico (the Mexican volcanic belt - MVB), based on records of shallow earthquakes that occurred in the zone between 1998 and 2011

    NASA Astrophysics Data System (ADS)

    Clemente-Chavez, A.; Zúñiga, F. R.; Lermo, J.; Figueroa-Soto, A.; Valdés, C.; Montiel, M.; Chavez, O.; Arroyo, M.

    2014-06-01

    The Mexican volcanic belt (MVB) is a seismogenic zone that transects the central part of Mexico with an east-west orientation. The seismic risk and hazard of this seismogenic zone has not been studied in detail due to the scarcity of instrumental data as well as because seismicity in the continental regime of central Mexico is not too frequent. However, it is known that there are precedents of large earthquakes (Mw > 6.0) that have taken place in this zone. The valley of Mexico City (VM) is the sole zone, within the MVB, that has been studied in detail. Studies have mainly focused on the ground amplification during large events such as the 1985 subduction earthquake that occurred off coast of Michoacán. The purpose of this article is to analyze the behavior of site effects in the MVB zone based on records of shallow earthquakes (data not reported before) that occurred in the zone between 1998 and 2011. We present a general overview of site effects in the MVB, a classification of the stations in order to reduce the uncertainty in the data when obtaining attenuation parameters in future works, as well as some comparisons between the information presented here and that presented in previous studies. A regional evaluation of site effects and Fourier acceleration spectrum (FAS) shape was estimated based on 80 records of 22 shallow earthquakes within the MVB zone. Data of 25 stations were analyzed. Site effects were estimated by using the horizontal-to-vertical spectral ratio (HVSR) methodology. The results show that seismic waves are less amplified in the northeast sites of the MVB with respect to the rest of the zone and that it is possible to classify two groups of stations: (1) stations with negligible site amplification (NSA) and (2) stations with significant site amplification (SSA). Most of the sites in the first group showed small (<3) amplifications while the second group showed amplifications ranging from 4 to 6.5 at frequencies of about 0.35, 0.75, 15 and 23

  15. Landslide in a Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The landslide in this VIS image is located inside an impact crater in the Elysium region of Mars. The unnamed crater is located at the margin of the volcanic flows from the Elysium Mons complex.

    Image information: VIS instrument. Latitude 1.2, Longitude 134 East (226 West). 19 meter/pixel resolution.

    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.

    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.

  16. Precursory Seismicity Associated With Landslides, Including the 2017 Tsunamigenic Landslide in the Karrat Fjord, Greenland

    NASA Astrophysics Data System (ADS)

    Caplan-Auerbach, J.

    2017-12-01

    On the evening of June 17 2017, a massive landslide fell from the wall of the Karrat Fjord, Greenland, generating a tsunami that caused the deaths of four residents in the nearby village of Nuugaatsiaq. The slide took place at a bluff 30 km from the village, where a broadband seismometer (DK.NUUG) is permanently deployed. The landslide generated a seismic signal initially interpreted as a magnitude 4.1 earthquake, as well as a tsunami that initially reached heights exceeding 100 m. Prior to the large seismic signal, however, station NUUG detected a series of several dozen small pulses, most of which were highly similar in time series. The pulses occur more frequently with time, until they effectively merge with the seismic signal of the landslide. The pulses were not detected on any other seismic stations, so their source locations cannot be calculated, but particle motions suggest that they were coming from an azimuth of 30o, consistent with the location of the landslide relative to Nuugaatsiaq. This particular sequence, in which small, repeating earthquakes occur with increasing frequency prior to a landslide, has been observed in at least four other locations: (1) on Mt. Baker (Washington) during an ice avalanche in 1976 (Weaver and Malone, 1979), (2) repeatedly on Iliamna volcano (Alaska) in association with glacial avalanches (Caplan-Auerbach and Huggel, 2007), (3) on Mt. Stellar (Alaska) prior to a 2006 rockfall (Huggel et al., 2010), and (4) as part of the Kausu landslide (Japan), in 2015 (Yamada et al., 2016). In all cases the precursory events exhibited waveform similarity, indicative of a repeating point of failure. These events represent stick-slip behavior at the landslide base. The precursory sequences last several hours, suggesting that detection of these events could provide a means of warning prior to failure. This may be useful in areas where instabilities or incipient failures are evident.

  17. Frictional velocity-weakening in landslides on Earth and on other planetary bodies.

    PubMed

    Lucas, Antoine; Mangeney, Anne; Ampuero, Jean Paul

    2014-03-04

    One of the ultimate goals in landslide hazard assessment is to predict maximum landslide extension and velocity. Despite much work, the physical processes governing energy dissipation during these natural granular flows remain uncertain. Field observations show that large landslides travel over unexpectedly long distances, suggesting low dissipation. Numerical simulations of landslides require a small friction coefficient to reproduce the extension of their deposits. Here, based on analytical and numerical solutions for granular flows constrained by remote-sensing observations, we develop a consistent method to estimate the effective friction coefficient of landslides. This method uses a constant basal friction coefficient that reproduces the first-order landslide properties. We show that friction decreases with increasing volume or, more fundamentally, with increasing sliding velocity. Inspired by frictional weakening mechanisms thought to operate during earthquakes, we propose an empirical velocity-weakening friction law under a unifying phenomenological framework applicable to small and large landslides observed on Earth and beyond.

  18. Forecasting volcanic eruptions and other material failure phenomena: An evaluation of the failure forecast method

    NASA Astrophysics Data System (ADS)

    Bell, Andrew F.; Naylor, Mark; Heap, Michael J.; Main, Ian G.

    2011-08-01

    Power-law accelerations in the mean rate of strain, earthquakes and other precursors have been widely reported prior to material failure phenomena, including volcanic eruptions, landslides and laboratory deformation experiments, as predicted by several theoretical models. The Failure Forecast Method (FFM), which linearizes the power-law trend, has been routinely used to forecast the failure time in retrospective analyses; however, its performance has never been formally evaluated. Here we use synthetic and real data, recorded in laboratory brittle creep experiments and at volcanoes, to show that the assumptions of the FFM are inconsistent with the error structure of the data, leading to biased and imprecise forecasts. We show that a Generalized Linear Model method provides higher-quality forecasts that converge more accurately to the eventual failure time, accounting for the appropriate error distributions. This approach should be employed in place of the FFM to provide reliable quantitative forecasts and estimate their associated uncertainties.

  19. Tsunami potential assessment based on rupture zones, focal mechanisms and repeat times of strong earthquakes in the major Atlantic-Mediterranean seismic fracture zone

    NASA Astrophysics Data System (ADS)

    Agalos, Apostolos; Papadopoulos, Gerassimos A.; Kijko, Andrzej; Papageorgiou, Antonia; Smit, Ansie; Triantafyllou, Ioanna

    2016-04-01

    In the major Atlantic-Mediterranean seismic fracture zone, extended from Azores islands in the west to the easternmost Mediterranean Sea in the east, including the Marmara and Black Seas, a number of 22 tsunamigenic zones have been determined from historical and instrumental tsunami documentation. Although some tsunamis were produced by volcanic activity or landslides, the majority of them was generated by strong earthquakes. Since the generation of seismic tsunamis depends on several factors, like the earthquake size, focal depth and focal mechanism, the study of such parameters is of particular importance for the assessment of the potential for the generation of future tsunamis. However, one may not rule out the possibility for tsunami generation in areas outside of the 22 zones determined so far. For the Atlantic-Mediterranean seismic fracture zone we have compiled a catalogue of strong, potentially tsunamigenic (focal depth less than 100 km) historical earthquakes from various data bases and other sources. The lateral areas of rupture zones of these earthquakes were determined. Rupture zone is the area where the strain after the earthquake has dropped substantially with respect the strain before the earthquake. Aftershock areas were assumed to determine areas of rupture zones for instrumental earthquakes. For historical earthquakes macroseismic criteria were used such as spots of higher-degree seismic intensity and of important ground failures. For the period of instrumental seismicity, focal mechanism solutions from CMT, EMMA and other data bases were selected for strong earthquakes. From the geographical distribution of seismic rupture zones and the corresponding focal mechanisms in the entire Atlantic-Mediterranean seismic fracture zone we determined potentially tsunamigenic zones regardless they are known to have produced seismic tsunamis in the past or not. An attempt has been made to calculate in each one of such zones the repeat times of strong

  20. On the behavior of site effects in Central Mexico (the Mexican Volcanic Belt - MVB), based on records of shallow earthquakes that occurred in the zone between 1998 and 2011

    NASA Astrophysics Data System (ADS)

    Clemente-Chavez, A.; Zúñiga, F. R.; Lermo, J.; Figueroa-Soto, A.; Valdés, C.; Montiel, M.; Chavez, O.; Arroyo, M.

    2013-11-01

    The Mexican Volcanic Belt (MVB) is a seismogenic zone that transects the central part of Mexico with an east-west orientation. The risk and hazard seismic of this seismogenic zone has not been studied at detail due to the scarcity of instrumental data as well as because seismicity in the continental regimen of Central Mexico is not too frequent, however, it is known that there are precedents of large earthquakes (Mw > 6.0) that have taken place in this zone. The Valley of Mexico City (VM) is the sole zone, within the MVB, which has been studied in detail; mainly focusing on the ground amplification during large events such as the 1985 subduction earthquake that occurred in Michoacan. The purpose of this article is to analyze the behavior of site effects in the MVB zone based on records of shallow earthquakes (data not reported before) that occurred in the zone between 1998 and 2011. We present a general overview of site effects on the MVB, a classification of the stations in order to reduce the uncertainty in the data to obtain attenuation parameters in future works, and some comparisons between the information presented here and that presented in previous studies. A regional evaluation of site effects and Fourier Acceleration Spectrum (FAS) shape was estimated based on 80 records of 22 shallow earthquakes within the MVB zone. Data of 25 stations were analyzed. Site effects were estimated by using the Horizontal-to-Vertical Spectral Ratio (HVSR) methodology. The results show that seismic waves are less amplified in the northeast sites of the MVB with respect to the rest of the zone and that it is possible to classify two groups of stations: (1) stations with Negligible Site Amplification (NSA) and (2) stations with Significant Site Amplification (SSA). Most of the sites in the first group showed small (< 3) amplifications while the second group showed amplifications ranging from 4 to 6.5 at frequencies of about 0.35, 0.75, 15 and 23 Hz. With these groups of

  1. A comparison of artifical and natural slope failures: the Santa Barbara earthquake of August 13, 1978.

    Harp, E.L.; Keefer, D.K.; Wilson, R.C.

    1980-01-01

    The earthquake triggered rockfalls and rockslides from steep road cuts and coastal cliffs. The landslide reconnaissance survey which was carried out is described, with separate comments on each landslide site recorded. The general regional slope response to the earthquake is briefly considered. -R. House

  2. Sedimentation influx and volcanic interactions in the Fuji Five Lakes: implications for paleoseismological records

    NASA Astrophysics Data System (ADS)

    Lamair, Laura; Hubert-Ferrari, Aurélia; Yamamoto, Shinya; El Ouahabi, Meriam; Garrett, Ed; Shishikura, Masanobu; Schmidt, Sabine; Boes, Evelien; Obrochta, Stephen; Nakamura, Atsunori; Miyairi, Yosuke; Yokoyama, Yusuke; De Batist, Marc; Heyvaert, Vanessa M. A.

    2017-04-01

    can be linked to the modification of the lake watershed by Mount Fuji volcanism, leading to a decrease in the sediment volume that can be remobilized, and therefore disappearance of large sublacustrine landslides. Turbidites are deposited due to surficial remobilization of lake slope sediments most probably as a result of earthquake shaking. When studying sedimentological records of lakes to define the paleoearthquake record, eruptions of nearby volcanoes should be taken into account. This study suggests that a large magnitude earthquake occurring few decades after a volcanic eruption (with large scale scoria fall-out), might not be recorded in a lake, or would only be fingerprinted in the sedimentary record by small turbiditic flows.

  3. Object-based Landslide Mapping: Examples, Challenges and Opportunities

    NASA Astrophysics Data System (ADS)

    Hölbling, Daniel; Eisank, Clemens; Friedl, Barbara; Chang, Kang-Tsung; Tsai, Tsai-Tsung; Birkefeldt Møller Pedersen, Gro; Betts, Harley; Cigna, Francesca; Chiang, Shou-Hao; Aubrey Robson, Benjamin; Bianchini, Silvia; Füreder, Petra; Albrecht, Florian; Spiekermann, Raphael; Weinke, Elisabeth; Blaschke, Thomas; Phillips, Chris

    2016-04-01

    Over the last decade, object-based image analysis (OBIA) has been increasingly used for mapping landslides that occur after triggering events such as heavy rainfall. The increasing availability and quality of Earth Observation (EO) data in terms of temporal, spatial and spectral resolution allows for comprehensive mapping of landslides at multiple scales. Most often very high resolution (VHR) or high resolution (HR) optical satellite images are used in combination with a digital elevation model (DEM) and its products such as slope and curvature. Semi-automated object-based mapping makes use of various characteristics of image objects that are derived through segmentation. OBIA enables numerous spectral, spatial, contextual and textural image object properties to be applied during an analysis. This is especially useful when mapping complex natural features such as landslides and constitutes an advantage over pixel-based image analysis. However, several drawbacks in the process of object-based landslide mapping have not been overcome yet. The developed classification routines are often rather complex and limited regarding their transferability across areas and sensors. There is still more research needed to further improve present approaches and to fully exploit the capabilities of OBIA for landslide mapping. In this study several examples of object-based landslide mapping from various geographical regions with different characteristics are presented. Examples from the Austrian and Italian Alps are shown, whereby one challenge lies in the detection of small-scale landslides on steep slopes while preventing the classification of false positives with similar spectral properties (construction areas, utilized land, etc.). Further examples feature landslides mapped in Iceland, where the differentiation of landslides from other landscape-altering processes in a highly dynamic volcanic landscape poses a very distinct challenge, and in Norway, which is exposed to multiple

  4. The Identification of Landslide Phases Based on Documentary Data in the Czech Republic

    NASA Astrophysics Data System (ADS)

    Bíl, Michal; Raška, Pavel; Sedoník, Jiří

    2017-04-01

    This paper focuses on landslide phases, this being a somewhat neglected aspect of landslide research. These are events during which an increased number of individual landslides have been concurrently activated. Landslide phases are an important proxy as their occurrence indicates the presence of a triggering event which predominantly involves thresholding rainfall or snow thaw. The research area corresponds to the Czech Republic (Czechia), herein represented by two regions accounting for the highest socioeconomic impact due to landsliding in the past. The Outer Western Carpathians to the east are built on relatively weak Tertiary flysch rocks, while the areas in the north-west of the Czech Republic have a diverse lithology including Mesozoic sandstone, Tertiary volcanic rocks and basin sediments, thus predisposing both landsliding and rockfall. It should also be noted that the identified landslide phases certainly had a cross-border and even Central European extent. The primary focus was on older events as the most recent landslide phases (1997, 2006 and 2010) have been sufficiently evidenced, while the older ones have not as yet been investigated enough. Identification of those older landslide phases can be carried out using documentary data, including chronicles of the affected villages and towns, newspapers, protoscientific communications or aerial photographs. The database on landslide events currently includes more than 570 records on old (pre- 1989) landsliding. At least 12 old landslide phases (when at least 10 landslides were registered) were identified from this database. Each data source has its own specific drawbacks which will be addressed. Chroniclers occasionally had a different view of the importance of natural processes and their impacts. Newspaper sources are quite sensitive to landslide events, but their availability strongly differs across individual regions as is the case with old maps and protoscientific communications. Eyewitnesses and persons

  5. Cosesimic landslides and their post-quake effects (Invited)

    NASA Astrophysics Data System (ADS)

    Huang, R.; Fan, X.

    2013-12-01

    On May 12, 2008, a devastating earthquake of magnitude Mw 7.9 hit China's Sichuan province. The quake, originating in the Longmen Shan fault zone at the eastern margin of Tibetan Plateau, was the country's largest seismic event in more than 50 years. It triggered more than 60,000 destructive landslides and 828 landslide dams over an area of 35,000 square kilometers, that caused about one third of the total fatalities. The combination of strong and long-lasting ground shaking, steep, rugged topography and a fragile and densely jointed lithology probably controlled the occurrence of landslides during the earthquake, but we found that other two factors (fault type and slip rate during the earthquake), may also have played a role. Landslides were clustered in a much wider corridor along the thrusting part of the Yingxiu-Beichuan fault than the strike-slip part. Large-scale landslides with an area of more than 50,000 m2 were concentrated where fault slip-rates were highest, near the intersections and junctures of individual segments of the fault. After the earthquake, debris flow hazard has become a significant concern. A tremendous amount of loose material from landslides that occurred during the earthquake is suspended on the hillslopes, ready to be eroded and transported by rain. More than 2000 occurrences of debris flow have been recorded by the Land and Resources Department of Sichuan Province following the 2008 quake till 2012. The threshold in hourly rainfall intensity for triggering debris flows was found to be around 60% lower after the earthquake than it had been before, according to the record in Beichuan. How long it will take for the debris flow frequency to return to pre-earthquake levels depends on a large number of factors, including rainfall intensity, natural re-vegetation and self-stabilization processes on slopes. We anticipate that - despite large uncertainties - debris flows that directly result from sediment movement during the 2008 earthquake may

  6. Monitoring landslide dynamics using timeseries of UAV imagery

    NASA Astrophysics Data System (ADS)

    de Jong, S. M.; Van Beek, L. P.

    2017-12-01

    Landslides are worldwide occurring processes that can have large economic impact and sometimes result in fatalities. Multiple factors are important in landslide processes and can make an area prone to landslide activity. Human factors like drainage and removal of vegetation or land clearing are examples of factors that may cause a landslide. Other environmental factors such as topography and the shear strength of the slope material are more difficult to control. Triggering factors for landslides are typically heavy rainfall events or sometimes by earthquakes or under cutting processes by a river. The collection of data about existing landslides in a given area is important for predicting future landslides in that region. We have setup a monitoring program for landslide using cameras aboard Unmanned Airborne Vehicles. UAV with cameras are able to collect ultra-high resolution images and UAVs can be operated in a very flexible way, they just fit in the back of a car. Here, in this study we used Unmanned Aerial Vehicles to collect a time series of high-resolution images over landslides in France and Australia. The algorithm used to process the UAV images into OrthoMosaics and OrthoDEMs is Structure from Motion (SfM). The process generally results in centimeter precision in the horizontal and vertical direction. Such multi-temporal datasets enable the detection of landslide area, the leading edge slope, temporal patterns and volumetric changes of particular areas of the landslide. We measured and computed surface movement of the landslide using the COSI-Corr image correlation algorithm with ground validation. Our study shows the possibilities of generating accurate Digital Surface Models (DSMs) of landslides using images collected with an Unmanned Aerial Vehicle (UAV). The technique is robust and repeatable such that a substantial time series of datasets can be routinely collected. It is shown that a time-series of UAV images can be used to map landslide movements with

  7. Landslide movement in southwest Colorado triggered by atmospheric tides

    Schulz, W.H.; Kean, J.W.; Wang, G.

    2009-01-01

    Landslides are among the most hazardous of geological processes, causing thousands of casualties and damage on the order of billions of dollars annually. The movement of most landslides occurs along a discrete shear surface, and is triggered by a reduction in the frictional strength of the surface. Infiltration of water into the landslide from rainfall and snowmelt and ground motion from earthquakes are generally implicated in lowering the frictional strength of this surface. However, solid-Earth and ocean tides have recently been shown to trigger shear sliding in other processes, such as earthquakes and glacial motion. Here we use observations and numerical modelling to show that a similar processatmospheric tidescan trigger movement in an ongoing landslide. The Slumgullion landslide, located in the SanJuan Mountains of Colorado, shows daily movement, primarily during diurnal low tides of the atmosphere. According to our model, the tidal changes in air pressure cause air and water in the sediment pores to flow vertically, altering the frictional stress of the shear surface; upward fluid flow during periods of atmospheric low pressure is most conducive to sliding. We suggest that tidally modulated changes in shear strength may also affect the stability of other landslides, and that the rapid pressure variations associated with some fast-moving storm systems could trigger a similar response. ?? 2009 Macmillan Publishers Limited. All rights reserved.

  8. Undersea landslides: Extent and significance in the Pacific Ocean, an update

    Lee, H.J.

    2005-01-01

    Submarine landslides are known to occur disproportionately in a limited number of environments including fjords, deltas, canyons, volcanic islands and the open continental slope. An evaluation of the progress that has been made in understanding Pacific Ocean submarine landslides over the last 15 years shows that mapping technologies have improved greatly, allowing a better interpretation of landslide features. Some features previously identified as landslides are being reinterpreted by some as sediment waves. Previously underappreciated environments for landslides such as deep-sea trenches are being recognized and lava deltas are being found to be landslide prone. Landslides are also being recognized much more commonly as a potential source of tsunamis. Landslides that have produced tsunamis in the past are being mapped and in some cases modeled. The flow characteristics of turbidity currents produced by landslides in canyon heads have recently been monitored and the source of these failures has been identified using repeated multibeam mapping. Finally, some landslide deposits are being dated as part of assessing risk to coastal cities from landslide-tsunamis. European Geosciences Union ?? 2005 Author(s). This work is licensed under a Creative Commons License.

  9. Cross-slope Movement Patterns in Landslides

    NASA Astrophysics Data System (ADS)

    Petley, D.; Murphy, W.; Bulmer, M. H.; Keefer, D.

    2002-12-01

    There is growing evidence that there is a significant element of cross-slope movement in many large landslide systems. These movements may result in changing states of stress between landslide blocks that can establish complex displacement patterns. Such motions, which are not considered in traditional two-dimensional limit-equilibrium analyses, are important in the investigation of a variety of landslide types, such as those triggered by earthquakes. In addition, these movements may introduce considerable errors into the interpretation of strain patterns as derived from InSAR studies. Finally, even traditional interpretation techniques may lead to the amount of total displacement being underestimated. These observations suggest that a three dimensional form of analysis may be more appropriate for large landslide complexes. The significance of such cross-slope movements are being investigated using a detailed investigation of the Lishan landslide complex in Central Taiwan. This landslide system, which was reactivated in 1990 related to the construction of a hotel. The total recorded movements have been approximately 1.5 m over an area of sliding that is estimated to be 450 m wide and 200 m long. Extensive damage has been caused to roads and buildings within the town. Remediation work has resulted largely in the stabilization of the landslide complex. Detailed geomorphological mapping has revealed that the landslide complex is composed of two main components. The first, immediately upslope of the hotel construction site, is a relatively shallow earthflow. The second, which has formed a large headscarp upslope from the main road in the centre of the town, is a deeper translational slide. Both appear to have been reactivations of previous failures. While the displacement patterns of the earthflow indicate a relatively simple downslope movement, the vectors derived from kinematic analysis of surface features have indicated that the movement of the deeper

  10. Landslide in Sirenum

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a landslide deposit in a deep trough in Terra Sirenum near 26.1oS, 140.0oW. After the landslide occurred, subsequent erosion of the slope produced talus that covers part of the landslide deposit. This area is about 3 km (1.9 mi) across; sunlight illuminates the scene from the lower left.

  11. Analysis of Tsunamigenic Coastal Rock Slope Failures Triggered by the 2007 Earthquake in the Chilean Fjordland

    NASA Astrophysics Data System (ADS)

    Sepulveda, S. A.; Serey, A.; Hermanns, R. L.; Redfield, T. F.; Oppikofer, T.; Duhart, P.

    2011-12-01

    The fjordland of the Chilean Patagonia is subject to active tectonics, with large magnitude subduction earthquakes, such as the M 9.5 1960 earthquake, and shallow crustal earthquakes along the regional Liquiñe-Ofqui Fault Zone (LOFZ). One of the latter (M 6.2) struck the Aysen Fjord region (45.5 S) on the 21st of April 2007, triggering dozens of landslides in the epicentral area along the fjord coast and surroundings. The largest rock slides and rock avalanches induced a local tsunami that together with debris flows caused ten fatalities and severely damaged several salmon farms, the most important economic activity of the area. Multi-scale studies of the landslides triggered during the Aysen earthquake have been carried out, including landslide mapping and classification, slope stability back-analyses and structural and geomorphological mapping of the largest failures from field surveys and high-resolution digital surface models created from terrestrial laser scanning. The failures included rock slides, rock avalanches, rock-soil slides, soil slides and debris flows. The largest rock avalanche had a volume of over 20 million cubic metres. The landslides affected steep slopes of intrusive rocks of the North Patagonian batholith covered by a thin layer of volcanic soils, which supports a high forest. The results of geotechnical analyses suggest a site effect due to topographic amplification on the generation of the landslides, with peak ground accelerations that may have reached between about 1.0 and 2.0 g for rock avalanches and between 0.6 and 1.0 g for shallow rock-soil slides, depending on the amount of assumed vertical acceleration and the applied method (limit equilibrium and Newmark). Attenuation relationships for shallow crustal seismicity indicate accelerations below 0.5 g for earthquakes of a similar magnitude and epicentral distances. Detailed field structural analyses of the largest rock avalanche in Punta Cola indicate a key role in the failure

  12. Microseismic Events Detection on Xishancun Landslide, Sichuan Province, China

    NASA Astrophysics Data System (ADS)

    Sheng, M.; Chu, R.; Wei, Z.

    2016-12-01

    On landslide, the slope movement and the fracturing of the rock mass often lead to microearthquakes, which are recorded as weak signals on seismographs. The distribution characteristics of temporal and spatial regional unstability as well as the impact of external factors on the unstable regions can be understand and analyzed by monitoring those microseismic events. Microseismic method can provide some information inside the landslide, which can be used as supplementary of geodetic methods for monitoring the movement of landslide surface. Compared to drilling on landslide, microseismic method is more economical and safe. Xishancun Landslide is located about 60km northwest of Wenchuan earthquake centroid, it keep deforming after the earthquake, which greatly increases the probability of disasters. In the autumn of 2015, 30 seismometers were deployed on the landslide for 3 months with intervals of 200 500 meters. First, we used regional earthquakes for time correction of seismometers to eliminate the influence of inaccuracy GPS clocks and the subsurface structure of stations. Due to low velocity of the loose medium, the travel time difference of microseismic events on the landslide up to 5s. According to travel time and waveform characteristics, we found many microseismic events and converted them into envelopes as templates, then we used a sliding-window cross-correlation technique based on waveform envelope to detect the other microseismic events. Consequently, 100 microseismic events were detected with the waveforms recorded on all seismometers. Based on the location, we found most of them located on the front of the landslide while the others located on the back end. The bottom and top of the landslide accumulated considerable energy and deformed largely, radiated waves could be recorded by all stations. What's more, the bottom with more events seemed very active. In addition, there were many smaller events happened in middle part of the landslide where released

  13. A method for producing digital probabilistic seismic landslide hazard maps

    Jibson, R.W.; Harp, E.L.; Michael, J.A.

    2000-01-01

    The 1994 Northridge, California, earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability. These data sets include: (1) a comprehensive inventory of triggered landslides, (2) about 200 strong-motion records of the mainshock, (3) 1:24 000-scale geologic mapping of the region, (4) extensive data on engineering properties of geologic units, and (5) high-resolution digital elevation models of the topography. All of these data sets have been digitized and rasterized at 10 m grid spacing using ARC/INFO GIS software on a UNIX computer. Combining these data sets in a dynamic model based on Newmark's permanent-deformation (sliding-block) analysis yields estimates of coseismic landslide displacement in each grid cell from the Northridge earthquake. The modeled displacements are then compared with the digital inventory of landslides triggered by the Northridge earthquake to construct a probability curve relating predicted displacement to probability of failure. This probability function can be applied to predict and map the spatial variability in failure probability in any ground-shaking conditions of interest. We anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure. ?? 2000 Elsevier Science B.V. All rights reserved.

  14. The threat of silent earthquakes

    Cervelli, Peter

    2004-01-01

    Not all earthquakes shake the ground. The so-called silent types are forcing scientists to rethink their understanding of the way quake-prone faults behave. In rare instances, silent earthquakes that occur along the flakes of seaside volcanoes may cascade into monstrous landslides that crash into the sea and trigger towering tsunamis. Silent earthquakes that take place within fault zones created by one tectonic plate diving under another may increase the chance of ground-shaking shocks. In other locations, however, silent slip may decrease the likelihood of destructive quakes, because they release stress along faults that might otherwise seem ready to snap.

  15. A Tool for Modelling the Probability of Landslides Impacting Road Networks

    NASA Astrophysics Data System (ADS)

    Taylor, Faith E.; Santangelo, Michele; Marchesini, Ivan; Malamud, Bruce D.; Guzzetti, Fausto

    2014-05-01

    Triggers such as earthquakes or heavy rainfall can result in hundreds to thousands of landslides occurring across a region within a short space of time. These landslides can in turn result in blockages across the road network, impacting how people move about a region. Here, we show the development and application of a semi-stochastic model to simulate how landslides intersect with road networks during a triggered landslide event. This was performed by creating 'synthetic' triggered landslide inventory maps and overlaying these with a road network map to identify where road blockages occur. Our landslide-road model has been applied to two regions: (i) the Collazzone basin (79 km2) in Central Italy where 422 landslides were triggered by rapid snowmelt in January 1997, (ii) the Oat Mountain quadrangle (155 km2) in California, USA, where 1,350 landslides were triggered by the Northridge Earthquake (M = 6.7) in January 1994. For both regions, detailed landslide inventory maps for the triggered events were available, in addition to maps of landslide susceptibility and road networks of primary, secondary and tertiary roads. To create 'synthetic' landslide inventory maps, landslide areas (AL) were randomly selected from a three-parameter inverse gamma probability density function, consisting of a power law decay of about -2.4 for medium and large values of AL and an exponential rollover for small values of AL. The number of landslide areas selected was based on the observed density of landslides (number of landslides km-2) in the triggered event inventories. Landslide shapes were approximated as ellipses, where the ratio of the major and minor axes varies with AL. Landslides were then dropped over the region semi-stochastically, conditioned by a landslide susceptibility map, resulting in a synthetic landslide inventory map. The originally available landslide susceptibility maps did not take into account susceptibility changes in the immediate vicinity of roads, therefore

  16. Development of a globally applicable model for near real-time prediction of seismically induced landslides

    Nowicki, M. Anna; Wald, David J.; Hamburger, Michael W.; Hearne, Mike; Thompson, Eric M.

    2014-01-01

    Substantial effort has been invested to understand where seismically induced landslides may occur in the future, as they are a costly and frequently fatal threat in mountainous regions. The goal of this work is to develop a statistical model for estimating the spatial distribution of landslides in near real-time around the globe for use in conjunction with the U.S. Geological Survey (USGS) Prompt Assessment of Global Earthquakes for Response (PAGER) system. This model uses standardized outputs of ground shaking from the USGS ShakeMap Atlas 2.0 to develop an empirical landslide probability model, combining shaking estimates with broadly available landslide susceptibility proxies, i.e., topographic slope, surface geology, and climate parameters. We focus on four earthquakes for which digitally mapped landslide inventories and well-constrainedShakeMaps are available. The resulting database is used to build a predictive model of the probability of landslide occurrence. The landslide database includes the Guatemala (1976), Northridge (1994), Chi-Chi (1999), and Wenchuan (2008) earthquakes. Performance of the regression model is assessed using statistical goodness-of-fit metrics and a qualitative review to determine which combination of the proxies provides both the optimum prediction of landslide-affected areas and minimizes the false alarms in non-landslide zones. Combined with near real-time ShakeMaps, these models can be used to make generalized predictions of whether or not landslides are likely to occur (and if so, where) for earthquakes around the globe, and eventually to inform loss estimates within the framework of the PAGER system.

  17. Spatial and temporal variability in rates of landsliding in seismically active mountain ranges

    NASA Astrophysics Data System (ADS)

    Parker, R.; Petley, D.; Rosser, N.; Densmore, A.; Gunasekera, R.; Brain, M.

    2012-04-01

    Where earthquake and precipitation driven disasters occur in steep, mountainous regions, landslides often account for a large proportion of the associated damage and losses. This research addresses spatial and temporal variability in rates of landslide occurrence in seismically active mountain ranges as a step towards developing better regional scale prediction of losses in such events. In the first part of this paper we attempt to explain reductively the variability in spatial rates of landslide occurrence, using data from five major earthquakes. This is achieved by fitting a regression-based conditional probability model to spatial probabilities of landslide occurrence, using as predictor variables proxies for spatial patterns of seismic ground motion and modelled hillslope stability. A combined model for all earthquakes performs well in hindcasting spatial probabilities of landslide occurrence as a function of readily-attainable spatial variables. We present validation of the model and demonstrate the extent to which it may be applied globally to derive landslide probabilities for future earthquakes. In part two we examine the temporal behaviour of rates of landslide occurrence. This is achieved through numerical modelling to simulate the behaviour of a hypothetical landscape. The model landscape is composed of hillslopes that continually weaken, fail and reset in response to temporally-discrete forcing events that represent earthquakes. Hillslopes with different geometries require different amounts of weakening to fail, such that they fail and reset at different temporal rates. Our results suggest that probabilities of landslide occurrence are not temporally constant, but rather vary with time, irrespective of changes in forcing event magnitudes or environmental conditions. Various parameters influencing the magnitude and temporal patterns of this variability are identified, highlighting areas where future research is needed. This model has important

  18. Landslide Hazard in Georgia

    NASA Astrophysics Data System (ADS)

    Gaprindashvili, G.; Tsereteli, E.; Gaprindashvili, M.

    2013-12-01

    In the last decades of the XX century, protect the population from geological hazards, to maintain land and safe operation of the engineering facilities has become the most important social - economic, demographic, political and environmental problems for the whole world. Georgia, with its scales of origination of the natural-catastrophic processes (landslide, mudflow, rockfall, erosion and etc.), their re-occurrence and with the negative results inflicted by these processes to the population, agricultural lands and engineering objects, is one of the most complex mountainous region. The extremely sensitive conditions were conditioned by: 1. Activation of highly intense earthquakes; 2. Activation of the negative meteorological events provoking the disaster processes on the background of global climatic changes and their abnormally frequent occurrence (mostly increased atmospheric precipitations, temperature and humidity); 3. Large-scale Human impact on the environment. Following the problem urgency, a number of departmental and research institutions have made their operations more intense in the given direction within the limits of their competence. First of all, the activity of the Department of Geology of Georgia (which is at present included in the National Environmental Agency of the Ministry of Environment and Natural Resources Protection), which mapped, identified and cataloged the hazardous processes on the territory of the country and identified the spatial limits and developmental regularities of these processes for tens of years. The increased risk of Geological catastrophes in Georgia first of all is caused by insufficient information between society and responsible persons toward this event. The existed situation needs the base assessment of natural disasters level, the identification of events, to determine their caused reasons, to develop special maps in GIS system, and continuous functioning of geo monitoring researches for develop safety early

  19. Landslide Hazard in Georgia

    NASA Astrophysics Data System (ADS)

    Gaprindashvili, George; Tsereteli, Emil; Gaprindashvili, Merab

    2014-05-01

    In the last decades of the XX century, protect the population from geological hazards, to maintain land and safe operation of the engineering facilities has become the most important social - economic, demographic, political and environmental problems for the whole world. Georgia, with its scales of origination of the natural-catastrophic processes (landslide, mudflow, rockfall, erosion and etc.), their re-occurrence and with the negative results inflicted by these processes to the population, agricultural lands and engineering objects, is one of the most complex mountainous region. The extremely sensitive conditions were conditioned by: 1. Activation of highly intense earthquakes; 2. Activation of the negative meteorological events provoking the disaster processes on the background of global climatic changes and their abnormally frequent occurrence (mostly increased atmospheric precipitations, temperature and humidity); 3. Large-scale Human impact on the environment. Following the problem urgency, a number of departmental and research institutions have made their operations more intense in the given direction within the limits of their competence. First of all, the activity of the Department of Geology of Georgia (which is at present included in the National Environmental Agency of the Ministry of Environment and Natural Resources Protection), which mapped, identified and cataloged the hazardous processes on the territory of the country and identified the spatial limits and developmental regularities of these processes for tens of years. The increased risk of Geological catastrophes in Georgia first of all is caused by insufficient information between society and responsible persons toward this event. The existed situation needs the base assessment of natural disasters level, the identification of events, to determine their caused reasons, to develop special maps in GIS system, and continuous functioning of geo monitoring researches for develop safety early

  20. Sichuan Earthquake in China

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Sichuan earthquake in China occurred on May 12, 2008, along faults within the mountains, but near and almost parallel the mountain front, northwest of the city of Chengdu. This major quake caused immediate and severe damage to many villages and cities in the area. Aftershocks pose a continuing danger, but another continuing hazard is the widespread occurrence of landslides that have formed new natural dams and consequently new lakes. These lakes are submerging roads and flooding previously developed lands. But an even greater concern is the possible rapid release of water as the lakes eventually overflow the new dams. The dams are generally composed of disintegrated rock debris that may easily erode, leading to greater release of water, which may then cause faster erosion and an even greater release of water. This possible 'positive feedback' between increasing erosion and increasing water release could result in catastrophic debris flows and/or flooding. The danger is well known to the Chinese earthquake response teams, which have been building spillways over some of the new natural dams.

    This ASTER image, acquired on June 1, 2008, shows two of the new large landslide dams and lakes upstream from the town of Chi-Kua-Kan at 32o12'N latitude and 104o50'E longitude. Vegetation is green, water is blue, and soil is grayish brown in this enhanced color view. New landslides appear bright off-white. The northern (top) lake is upstream from the southern lake. Close inspection shows a series of much smaller lakes in an elongated 'S' pattern along the original stream path. Note especially the large landslides that created the dams. Some other landslides in this area, such as the large one in the northeast corner of the image, occur only on the mountain slopes, so do not block streams, and do not form lakes.

  1. Catastrophic volcanism

    NASA Technical Reports Server (NTRS)

    Lipman, Peter W.

    1988-01-01

    Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

  2. An Atlas of ShakeMaps for Landslide and Liquefaction Modeling

    NASA Astrophysics Data System (ADS)

    Johnson, K. L.; Nowicki, M. A.; Mah, R. T.; Garcia, D.; Harp, E. L.; Godt, J. W.; Lin, K.; Wald, D. J.

    2012-12-01

    The human consequences of a seismic event are often a result of subsequent hazards induced by the earthquake, such as landslides. While the United States Geological Survey (USGS) ShakeMap and Prompt Assessment of Global Earthquakes for Response (PAGER) systems are, in conjunction, capable of estimating the damage potential of earthquake shaking in near-real time, they do not currently provide estimates for the potential of further damage by secondary processes. We are developing a sound basis for providing estimates of the likelihood and spatial distribution of landslides for any global earthquake under the PAGER system. Here we discuss several important ingredients in this effort. First, we report on the development of a standardized hazard layer from which to calibrate observed landslide distributions; in contrast, prior studies have used a wide variety of means for estimating the hazard input. This layer now takes the form of a ShakeMap, a standardized approach for computing geospatial estimates for a variety of shaking metrics (both peak ground motions and shaking intensity) from any well-recorded earthquake. We have created ShakeMaps for about 20 historical landslide "case history" events, significant in terms of their landslide occurrence, as part of an updated release of the USGS ShakeMap Atlas. We have also collected digitized landslide data from open-source databases for many of the earthquake events of interest. When these are combined with up-to-date topographic and geologic maps, we have the basic ingredients for calibrating landslide probabilities for a significant collection of earthquakes. In terms of modeling, rather than focusing on mechanistic models of landsliding, we adopt a strictly statistical approach to quantify landslide likelihood. We incorporate geology, slope, peak ground acceleration, and landslide data as variables in a logistic regression, selecting the best explanatory variables given the standardized new hazard layers (see Nowicki

  3. Earthquake Drill using the Earthquake Early Warning System at an Elementary School

    NASA Astrophysics Data System (ADS)

    Oki, Satoko; Yazaki, Yoshiaki; Koketsu, Kazuki

    2010-