Identifying Potential Collapse Features Under Highways

DOT National Transportation Integrated Search

2003-01-01

In 1994, subsidence features were identified on Interstate 70 in eastern Ohio. These : features were caused by collapse of old mine workings beneath the highway. An attempt : was made to delineate these features using geophysical methods with no avai...

Identifying Potential Collapse Features Under Highways : Executive Summary

DOT National Transportation Integrated Search

2003-03-01

In 1994, subsidence features were identified on Interstate 70 in eastern Ohio. These : features were caused by collapse of old mine workings beneath the highway. An attempt : was made to delineate these features using geophysical methods with no avai...

Identifying potential collapse features under highways.

DOT National Transportation Integrated Search

2003-03-01

In 1994, subsidence features were identified on Interstate 70 in eastern Ohio. These features were caused by collapse of old mine workings beneath the highway. An attempt was made to delineate these features using geophysical methods with no avail. T...

Venus: Preliminary geologic mapping of northern Atla Regio

NASA Technical Reports Server (NTRS)

Nikishin, A. M.; Burba, G. A.

1992-01-01

A preliminary geologic map of C1 sheet 15N197 was compiled according to Magellan data. Northern Atla Regio is dominantly a volcanic plain with numerous volcanic features: radar-bright and -dark flows and spots, shield volcanos, volcanic domes and hills with varied morphology, and coronalike constructions. Tesserae are the oldest terrains semiflooded by plain materials. There are many lineated terrains on this territory. They are interpreted as old, partly buried ridge belts. Lineated terrains have intermediate age between young plains and old tesserae. Ozza Mons and Sapas Mons are the high shield volcanos. The prominent structure of northern Atla Regio is Ganis Chasma rift. The rift dissected the volcanic plain and evolved nearly contemporaneously with Ozza Mons shield volcano. Ganis Chasma rift valley is highly fractured and bounded by fault scarps. There are a few relatively young volcanic features in the rift valley. The rift originated due to 5-10 percent crustal extension and crustal subsidence according to analysis of fracturing and rift valley geometry. Ganis Chasma is characterized by rift shoulder uplifts. Geological structures of Alta Regio and Beta Regio are very similar as assumed earlier.

Collaboration and Subsidized Early Care and Education Programs in Illinois

ERIC Educational Resources Information Center

Spielberger, Julie; Zanoni, Wladimir; Barisik, Elizabeth

2013-01-01

As a result of policy changes following welfare reform in 1996 and the costs associated with providing high-quality early care and education for children of low-income working families, agency collaboration in the state of Illinois has become an increasingly salient feature of subsidized early care and education programs (SECE). The authors…

State budget transfers to Health Insurance to expand coverage to people outside formal sector work in Latin America.

PubMed

Mathauer, Inke; Behrendt, Thorsten

2017-02-16

Contributory social health insurance for formal sector employees only has proven challenging for moving towards universal health coverage (UHC). This is because the informally employed and the poor usually remain excluded. One way to expand UHC is to fully or partially subsidize health insurance contributions for excluded population groups through government budget transfers. This paper analyses the institutional design features of such government subsidization arrangements in Latin America and assesses their performance with respect to UHC progress. The aim is to identify UHC conducive institutional design features of such arrangements. A literature search provided the information to analyse institutional design features, with a focus on the following aspects: eligibility/enrolment rules, financing and pooling arrangements, and purchasing and benefit package design. Based on secondary data analysis, UHC progress is assessed in terms of improved population coverage, financial protection and access to needed health care services. Such government subsidization arrangements currently exist in eight countries of Latin America (Bolivia, Chile, Colombia, Costa Rica, Dominican Republic, Mexico, Peru, Uruguay). Institutional design features and UHC related performance vary significantly. Notably, countries with a universalist approach or indirect targeting have higher population coverage rates. Separate pools for the subsidized maintain inequitable access. The relatively large scopes of the benefit packages had a positive impact on financial protection and access to care. In the long term, merging different schemes into one integrated health financing system without opt-out options for the better-off is desirable, while equally expanding eligibility to cover those so far excluded. In the short and medium term, the harmonization of benefit packages could be a priority. UHC progress also depends on substantial supply side investments to ensure the availability of quality services, particularly in rural areas. Future research should generate more evidence on the implementation process and impact of subsidization arrangements on UHC progress.

Features of development process displacement of earth’s surface when dredging coal in Eastern Donbas

NASA Astrophysics Data System (ADS)

Posylniy, Yu V.; Versilov, S. O.; Shurygin, D. N.; Kalinchenko, V. M.

2017-10-01

The results of studies of the process of the earth’s surface displacement due to the influence of the adjacent longwalls are presented. It is established that the actual distributions of soil subsidence in the fall and revolt of the reservoir with the same boundary settlement processes differ both from each other and by the distribution of subsidence, recommended by the rules of structures protection. The application of the new boundary criteria - the relative subsidence of 0.03 - allows one to go from two distributions to one distribution, which is also different from the sedimentation distribution of protection rules. The use of a new geometrical element - a virtual point of the mould - allows one to transform the actual distribution of subsidence in the model distribution of rules of constructions protection. When transforming the curves of subsidence, the boundary points vary and, consequently, the boundary corners do.

The Next Generation in Subsidence and Aquifer-System Compaction Modeling within the MODFLOW Software Family: A New Package for MODFLOW-2005 and MODFLOW-OWHM

NASA Astrophysics Data System (ADS)

Boyce, S. E.; Leake, S. A.; Hanson, R. T.; Galloway, D. L.

2015-12-01

The Subsidence and Aquifer-System Compaction Packages, SUB and SUB-WT, for MODFLOW are two currently supported subsidence packages within the MODFLOW family of software. The SUB package allows the calculation of instantaneous and delayed releases of water from distributed interbeds (relatively more compressible fine-grained sediments) within a saturated aquifer system or discrete confining beds. The SUB-WT package does not include delayed releases, but does perform a more rigorous calculation of vertical stresses that can vary the effective stress that causes compaction. This calculation of instantaneous compaction can include the effect of water-table fluctuations for unconfined aquifers on effective stress, and can optionally adjust the elastic and inelastic storage properties based on the changes in effective stress. The next generation of subsidence modeling in MODFLOW is under development, and will merge and enhance the capabilities of the SUB and SUB-WT Packages for MODFLOW-2005 and MODFLOW-OWHM. This new version will also provide some additional features such as stress dependent vertical hydraulic conductivity of interbeds, time-varying geostatic loads, and additional attributes related to aquifer-system compaction and subsidence that will broaden the class of problems that can be simulated. The new version will include a redesigned source code, a new user friendly input file structure, more output options, and new subsidence solution options. This presentation will discuss progress in developing the new package and the new features being implemented and their potential applications. By Stanley Leake, Scott E. Boyce, Randall T. Hanson, and Devin Galloway

Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

NASA Astrophysics Data System (ADS)

Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

2016-06-01

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992-2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr-1 with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr-1. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr-1 and cumulative subsidence as much as 155 cm.

Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

PubMed Central

Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

2016-01-01

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr−1 with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr−1. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr−1 and cumulative subsidence as much as 155 cm. PMID:27324935

Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China.

PubMed

Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C K; Galloway, Devin L; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

2016-06-21

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992-2015 show time-varying trends with respect to displacement over time in California's San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr(-1) with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr(-1). Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr(-1) and cumulative subsidence as much as 155 cm.

Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China

USGS Publications Warehouse

Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C.K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei

2016-01-01

Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and ice sheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm/yr with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm/yr. Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm/yr and cumulative subsidence as much as 155 cm.

Evaluating the anthropogenic impacts on fluvial flood risks in a coastal mega-city during its transitional economy (1979-2009): the interaction between land subsidence, urbanization and structural measures

NASA Astrophysics Data System (ADS)

Yu, Dapeng; Yin, Jie

2014-05-01

Flood risk in a specific geographical location is a function of the interaction between various natural (e.g. rainfall, sea-level rise) and anthropogenic processes (e.g. land subsidence and urbanization). These processes, whether a driver or an alleviating factor, often encompass a large degree of spatial and temporal variability. Looking at a specific process in isolation is likely to provide an incomplete picture of the risks. This paper describes a novel approach to the evaluation of anthropogenic impacts on flood risks in coastal mega-cities by incorporating three anthropogenic variables (land subsidence, urbanization and flood defence) within a scenario-based framework where numerical modelling was undertaken to quantify the risks. The evolving risks at four time points (1979, 1990, 2000 and 2009) were assessed for the Huangpu River floodplain where the City of Shanghai is located. Distributed data of land subsidence rate, urbanization rate and flood defence heights were obtained. Scenarios were designed by representing the rate of land subsidence and flood defence height through the modification of DEM. Effect of urbanization is represented by a roughness parameter in the model simulations. A 2D hydrodynamic model (FloodMap-Inertial) was used to estimate the flood risks associated with each scenario. Flood events with various return periods (10-, 100- and 1000-year) were designed based on a one in 50 year flood event occurred in Shanghai in August 1997. Results demonstrate the individual as well as the combined impacts of the three anthropogenic factors on the changing fluvial flood risks in the Huangpu River basin over the last three decades during the city's transitional economy (1979-2009). Land subsidence and urbanization were found to lead to proportionate but non-linear impact on flood risks due to their complex spatial and temporal interaction. The impacts and their sensitivity are the function of the rate & spatial distribution of each evolving factor. They also manifest differently in floods of different magnitude. While the pattern of response to individual anthropogenic variables is largely expected, the combined impacts demonstrate greater spatial and temporal variation. Flood defences offer considerable benefits in reducing the total inundated areas in the Huangpu River basin over the periods considered, for all magnitude floods. This, to a large extent, alleviates the adverse impacts arising from land subsidence and urbanization. However, even with an enclosed and completed defence system in 2009, extensive flood inundation is still expected for a 10-year event, albeit largely restricted to the upstream of the river where urban settlements are limited. The scenario-based approach described herein could be adopted for applications in other urbanized and subsided coastal floodplains, especially in places where the rate of land subsidence is still accelerating, urbanization is still undergoing and the local sea level keeps rising. Risk scenarios that encompass probable future anthropogenic projections may assist decision makers and other concerned stakeholders in better understanding the underlying drivers of changing flood risks, and thus help to design proper adaptation options for sustainable flood risk management and urban planning.

Ring-fault activity at subsiding calderas studied from analogue experiments and numerical modeling

NASA Astrophysics Data System (ADS)

Liu, Y. K.; Ruch, J.; Vasyura-Bathke, H.; Jonsson, S.

2017-12-01

Several subsiding calderas, such as the ones in the Galápagos archipelago and the Axial seamount in the Pacific Ocean have shown a complex but similar ground deformation pattern, composed of a broad deflation signal affecting the entire volcanic edifice and of a localized subsidence signal focused within the caldera. However, it is still debated how deep processes at subsiding calderas, including magmatic pressure changes, source locations and ring-faulting, relate to this observed surface deformation pattern. We combine analogue sandbox experiments with numerical modeling to study processes involved from initial subsidence to later collapse of calderas. The sandbox apparatus is composed of a motor driven subsiding half-piston connected to the bottom of a glass box. During the experiments the observation is done by five digital cameras photographing from various perspectives. We use Photoscan, a photogrammetry software and PIVLab, a time-resolved digital image correlation tool, to retrieve time-series of digital elevation models and velocity fields from acquired photographs. This setup allows tracking the processes acting both at depth and at the surface, and to assess their relative importance as the subsidence evolves to a collapse. We also use the Boundary Element Method to build a numerical model of the experiment setup, which comprises contracting sill-like source in interaction with a ring-fault in elastic half-space. We then compare our results from these two approaches with the examples observed in nature. Our preliminary experimental and numerical results show that at the initial stage of magmatic withdrawal, when the ring-fault is not yet well formed, broad and smooth deflation dominates at the surface. As the withdrawal increases, narrower subsidence bowl develops accompanied by the upward propagation of the ring-faulting. This indicates that the broad deflation, affecting the entire volcano edifice, is primarily driven by the contraction of the magmatic source, whereas the ring-faulting tends to concentrate deformation within the caldera. This interaction between ring-faulting and pressure decrease in a magma reservoir therefore provides a possible explanation for the deformation pattern observed at several subsiding calderas.

Well known outstanding geoid and relief depressions as regular wave woven features on Eartg (Indian geoid minimum), Moon (SPA basin), Phobos (Stickney crater), and Miranda (an ovoid).

NASA Astrophysics Data System (ADS)

Kochemasov, Gennady G.

2010-05-01

A very unreliable interpretation of the deepest and large depressions on the Moon and Phobos as the impact features is not synonymous and causes many questions. A real scientific understanding of their origin should take into consideration a fact of their similar tectonic position with that of a comparable depression on so different by size, composition, and density heavenly body as Earth. On Earth as on other celestial bodies there is a fundamental division on two segments - hemispheres produced by an interference of standing warping wave 1 (long 2πR) of four directions [1]. One hemisphere is uplifted (continental, highlands) and the opposite subsided (oceanic, lowlands). Tectonic features made by wave 2 (sectors) adorn this fundamental structure. Thus, on the continental risen segment appear regularly disposed sectors, also uplifted and subsided. On the Earth's eastern continental hemisphere they are grouped around the Pamirs-Hindukush vertex of the structural octahedron made by interfering waves2. Two risen sectors (highly uplifted African and the opposite uplifted Asian) are separated by two fallen sectors (subsided Eurasian and the opposite deeply subsided Indoceanic). The Indoceanic sector with superposed on it subsided Indian tectonic granule (πR/4-structure) produce the deepest geoid minimum of Earth (-112 m). The Moon demonstrates its own geoid minimum of the same relative size and in the similar sectoral tectonic position - the SPA basin [2, 3]. This basin represents a deeply subsided sector of the sectoral structure around the Mare Orientale (one of vertices of the lunar structural octahedron). To this Mare converge four sectors: two subsided - SPA basin and the opposite Procellarum Ocean, and two uplifted - we call them the "Africanda sector" and the opposite "Antiafricanda one" to stress structural similarity with Earth [2]. The highest "Africanda sector" is built with light anorthosites; enrichment with Na makes them even less dense that is required by the sector highest elevation. Procellarum Ocean is filled with basalts and Ti-basalts. The SPA basin must be filled with even denser rocks. One expects here feldspar-free, pyroxene enriched rocks with some admixture of Fe metal and troilite. The spectral observations of Carle Pieters [4] confirm orthopyroxene enrichment and absence of feldspar. Enigmatic large and deep depression of crater Stickney on Phobos with an appropriate scale adjustment to much larger Earth and Moon occupies a similar structural position to the Indian geoid minimum and the SPA basin. Such situation cannot be random and proves a common origin of these remarkable tectonic features at so different celestial bodies. This conclusion is reinforced by taking for a comparison another small heavenly body- Uranus satellite Miranda. Imaged by Voyager 2 spacecraft in 1986 it shows two kinds of terrains (PIA01980 & others). Subsided provinces (ovoids) characterized by intensive curvilinear folding and faulting interrupt uplifted densely cratered old provinces. One of the deeply subsided ovoids with curvilinear folds pattern (compression under subsidence) perfectly fits into a sector boundary. References: [1] Kochemasov G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., V.1, #3, 700. [2] Kochemasov G.G. (1998) The Moon: Earth-type sectoral tectonics, relief and relevant chemical features // The 3rd International Confernce on Exploration and Utilization of the Moon, Oct. 11-14, 1998, Moscow, Russia, Abstracts, p. 29. [3] Kochemasov G.G. (1998) Moon-Earth: similarity of sectoral organization // 32nd COSPAR Scientific Assembly, Nagoya, Japan, 12-19 July 1998, Abstracts, p. 77. [4] Pieters C. (1997) Annales Geophys., v. 15, pt. III, p. 792.

Land subsidence and earth fissures in south-central and southern Arizona, USA

NASA Astrophysics Data System (ADS)

Conway, Brian D.

2016-05-01

Land subsidence due to groundwater overdraft has been an ongoing problem in south-central and southern Arizona (USA) since the 1940s. The first earth fissure attributed to excessive groundwater withdrawal was discovered in the early 1950s near Picacho. In some areas of the state, groundwater-level declines of more than 150 m have resulted in extensive land subsidence and earth fissuring. Land subsidence in excess of 5.7 m has been documented in both western metropolitan Phoenix and Eloy. The Arizona Department of Water Resources (ADWR) has been monitoring land subsidence since 2002 using interferometric synthetic aperture radar (InSAR) and since 1998 using a global navigation satellite system (GNSS). The ADWR InSAR program has identified more than 25 individual land subsidence features that cover an area of more than 7,300 km2. Using InSAR data in conjunction with groundwater-level datasets, ADWR is able to monitor land subsidence areas as well as identify areas that may require additional monitoring. One area of particular concern is the Willcox groundwater basin in southeastern Arizona, which is the focus of this paper. The area is experiencing rapid groundwater declines, as much as 32.1 m during 2005-2014 (the largest land subsidence rate in Arizona State—up to 12 cm/year), and a large number of earth fissures. The declining groundwater levels in Arizona are a challenge for both future groundwater availability and mitigating land subsidence associated with these declines. ADWR's InSAR program will continue to be a critical tool for monitoring land subsidence due to excessive groundwater withdrawal.

InSAR Measurements of Non-Tectonic Deformation Patterns in the Western Transverse Ranges, CA

NASA Astrophysics Data System (ADS)

Phillips, J. R., III; Marshall, S. T.; Funning, G.

2014-12-01

We present results from analysis of twenty-two scenes from the Envisat satellite dated between February 2005 and September 2010 along track 213 frames 2907 and 2925 in the Western Transverse Ranges, CA. Persistent Scatterer InSAR (PSI) analysis of interferograms was performed using the StaMPS software package resulting in approximately 2 million PSI points with their associated line-of-sight velocities and time series. These data outline several zones of anthropogenic motion likely due to groundwater usage and oil extraction. We identify two instances of highly localized subsidence due to oil extraction: one of up to 6 mm/yr across a 3x5 km wide oval-shaped zone along the Ventura Ave anticline and another of up to 12 mm/yr across a 3x15 km region near Maricopa. Both of these features are observed in regions of known oil extraction, and the subsidence zones parallel the local fold axes, suggesting that these observed features are real and not merely a product of noise. We also observe several features potentially related to groundwater extraction. The groundwater-related signals tend to be less localized than the oil extraction signals and typically are centered around urban or agricultural areas. The PSI data show a broad zone of subsidence in the greater Oxnard region (10 mm/yr maximum), and more localized zones of subsidence centered in the cities of Carpenteria (4 mm/yr), Ojai (4 mm/yr), and Santa Clarita (5 mm/yr). Several additional regions of potentially anthropogenic motion are also present in the PSI data to which the root cause is unclear. For example, we observe localized uplift of 5 mm/yr centered in the Stevenson Ranch housing development, 8 mm/yr of subsidence centered about 5 km NW of Moorpark near a large agricultural nursery, and a potentially tectonic broad pattern of 4 mm/yr of uplift in the mountains of Los Padres National Forest near Frasier Mountain.

Topography of the Overriding Plate During Progressive Subduction: A Dynamic Model to Explain Forearc Subsidence

NASA Astrophysics Data System (ADS)

Chen, Zhihao; Schellart, Wouter P.; Duarte, João. C.; Strak, Vincent

2017-10-01

Overriding plate topography provides constraints on subduction zone geodynamics. We investigate its evolution using fully dynamic laboratory models of subduction with techniques of stereoscopic photogrammetry and particle image velocimetry. Model results show that the topography is characterized by an area of forearc dynamic subsidence, with a magnitude scaling to 1.44-3.97 km in nature, and a local topographic high between the forearc subsided region and the trench. These topographic features rapidly develop during the slab free-sinking phase and gradually decrease during the steady state slab rollback phase. We propose that they result from the variation of the vertical component of the trench suction force along the subduction zone interface, which gradually increases with depth and results from the gradual slab steepening during the initial transient slab sinking phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in driving forearc subsidence.

Relating large-scale subsidence to convection development in Arctic mixed-phase marine stratocumulus

NASA Astrophysics Data System (ADS)

Young, Gillian; Connolly, Paul J.; Dearden, Christopher; Choularton, Thomas W.

2018-02-01

Large-scale subsidence, associated with high-pressure systems, is often imposed in large-eddy simulation (LES) models to maintain the height of boundary layer (BL) clouds. Previous studies have considered the influence of subsidence on warm liquid clouds in subtropical regions; however, the relationship between subsidence and mixed-phase cloud microphysics has not specifically been studied. For the first time, we investigate how widespread subsidence associated with synoptic-scale meteorological features can affect the microphysics of Arctic mixed-phase marine stratocumulus (Sc) clouds. Modelled with LES, four idealised scenarios - a stable Sc, varied droplet (Ndrop) or ice (Nice) number concentrations, and a warming surface (representing motion southwards) - were subjected to different levels of subsidence to investigate the cloud microphysical response. We find strong sensitivities to large-scale subsidence, indicating that high-pressure systems in the ocean-exposed Arctic regions have the potential to generate turbulence and changes in cloud microphysics in any resident BL mixed-phase clouds.Increased cloud convection is modelled with increased subsidence, driven by longwave radiative cooling at cloud top and rain evaporative cooling and latent heating from snow growth below cloud. Subsidence strengthens the BL temperature inversion, thus reducing entrainment and allowing the liquid- and ice-water paths (LWPs, IWPs) to increase. Through increased cloud-top radiative cooling and subsequent convective overturning, precipitation production is enhanced: rain particle number concentrations (Nrain), in-cloud rain mass production rates, and below-cloud evaporation rates increase with increased subsidence.Ice number concentrations (Nice) play an important role, as greater concentrations suppress the liquid phase; therefore, Nice acts to mediate the strength of turbulent overturning promoted by increased subsidence. With a warming surface, a lack of - or low - subsidence allows for rapid BL turbulent kinetic energy (TKE) coupling, leading to a heterogeneous cloud layer, cloud-top ascent, and cumuli formation below the Sc cloud. In these scenarios, higher levels of subsidence act to stabilise the Sc layer, where the combination of these two forcings counteract one another to produce a stable, yet dynamic, cloud layer.

Advance and application of the stratigraphic simulation model 2D- SedFlux: From tank experiment to geological scale simulation

NASA Astrophysics Data System (ADS)

Kubo, Yu'suke; Syvitski, James P. M.; Hutton, Eric W. H.; Paola, Chris

2005-07-01

The stratigraphic simulation model 2D- SedFlux is further developed and applied to a turbidite experiment in a subsiding minibasin. The new module dynamically simulates evolving hyperpycnal flows and their interaction with the basin bed. Comparison between the numerical results and the experimental results verifies the ability of 2D- SedFlux to predict the distribution of the sediments and the possible feedback from subsidence. The model was subsequently applied to geological-scale minibasins such as are located in the Gulf of Mexico. Distance from the sediment source is determined to be more influential than the sediment entrapment in upstream minibasin. The results suggest that efficiency of sediment entrapment by a basin was not influenced by the distance from the sediment source.

Sedimentation and subsidence patterns in the central and north basins of Lake Baikal from seismic stratigraphy

USGS Publications Warehouse

Moore, T.C.; Klitgord, Kim D.; Golmshtok, A.J.; Weber, E.

1997-01-01

Comparison of sedimentation patterns, basement subsidence, and faulting histories in the north and central basins of Lake Baikal aids in developing an interbasinal seismic stratigraphy that reveals the early synrift evolution of the central portion of the Baikal rift, a major continental rift system. Although there is evidence that the central and northern rift basins evolved at approximately the same time, their sedimentation histories are markedly different. Primary sediment sources for the initial rift phase were from the east flank of the rift; two major deltas developed adjacent to the central basin: the Selenga delta at the south end and the Barguzin delta at the north end. The Barguzin River system, located at the accommodation zone between the central and north basins, also fed into the southern part of the north basin and facilitated the stratigraphic linkage of the two basins. A shift in the regional tectonic environment in the mid Pliocene(?) created a second rift phase distinguished by more rapid subsidence and sediment accumulation in the north basin and by increased subsidence and extensive faulting in the central basin. The Barguzin delta ceased formation and parts of the old delta system were isolated within the north basin and on Academic Ridge. These isolated deltaic deposits provide a model for the development of hydrocarbon plays within ancient rift systems. In this second tectonic phase, the dominant sediment fill in the deeper and more rapidly subsiding north basin shifted from the flexural (eastern) margin to axial transport from the Upper Angara River at the north end of the basin.

Closing the Skills Gap: A Blueprint for Preparing New York City's Workforce to Meet the Evolving Needs of Employers

ERIC Educational Resources Information Center

Fischer, David Jason; Reiss, Jeremy

2010-01-01

While public attention remains focused on the highest unemployment numbers in a generation, New York City is drifting toward a structural crisis with which policy makers could be grappling long after the recession fades to a bad memory. Even as the concerns about financial capital that spurred the downturn begin to subside, public officials must…

Chimney subsidence development in the Colorado Springs coal field, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matheson, G.M.; Pearson, M.L.

1985-01-01

Mining in the Colorodo Springs coal field took place from the 1880's to 1940's. The depth of mining in the coal field varied from about 10 meters to over 150 meters. Review of sequential historical aerial photographs from 1937 to 1960 indicated about 2400 chimney subsidence sinkholes had developed throughout the study area. Statistical analyses of the location and size of these sinkholes with respect to the time since mining, depth of mining, mined thickness and type of mining indicated definite trends in the time of occurrence, size, and location of these features. This data is valuable in the assessmentmore » of potential future subsidence in this and other areas of similar mining conditions.« less

Surface subsidence and collapse in relation to extraction of salt and other soluble evaporites

USGS Publications Warehouse

Ege, John R.

1979-01-01

Extraction of soluble minerals, whether by natural or man-induced processes, can result in localized land-surface subsidence and more rarely sinkhole formation. One process cited by many investigators is that uncontrolled dissolving of salt or other soluble evaporites can create or enlarge underground cavities, thereby increasing the span of the unsupported roof to the strength limit of the overlying rocks. Downwarping results when spans are exceeded, or collapse of the undermined roof leads to upward sloping or chimneying of the overburden rocks. If underground space is available for rock debris to collect, the void can migrate to the surface with the end result being surface subsidence or collapse. In North America natural solution subsidence and collapse features in rocks ranging in age from Silurian to the present are found in evaporite terranes in the Great Plains from Saskatchewan in the north to Texas and New Mexico in the south, in the Great Lakes area, and in the southeastern States. Man-induced subsidence and collapse in evaporites are generally associated with conventional or solution mining, oilfield operations, and reservoir and dam construction, and can be especially hazardous in populated or built-up areas.

Integrated geophysical survey in defining subsidence features on a golf course

USGS Publications Warehouse

Xia, J.; Miller, R.D.

2007-01-01

Subsidence was observed at several places on the Salina Municipal Golf Course in areas known to be built over a landfill in Salina, Kansas. High-resolution magnetic survey (???5400 m2), multi-channel electrical resistivity profiling (three 154 m lines) and microgravity profiling (23 gravity-station values) were performed on a subsidence site (Green 16) to aid in determining boundaries and density deficiency of the landfill in the vicinity of the subsidence. Horizontal boundaries of the landfill were confidently defined by both magnetic anomalies and the pseudo-vertical gradient of total field magnetic anomalies. Furthermore, the pseudo-vertical gradient of magnetic anomalies presented a unique anomaly at Green 16, which provided a criterion for predicting other spots with subsidence potential using the same gradient property. Results of multi-channel electrical resistivity profiling (ERP) suggested the bottom limit of the landfill at Green 16 was around 21 m below the ground surface based on the vertical gradient of electric resistivity and a priori information on the depth of the landfill. ERP results also outlined several possible landfill bodies based on their low resistivity values. Microgravity results suggested a -0.14 g cm-3 density deficiency at Green 16 that could equate to future surface subsidence of as much as 1.5 m due to gradual compaction. ?? 2007 Nanjing Institute of Geophysical Prospecting.

Evolution of the Neogene Andean foreland basins of the Southern Pampas and Northern Patagonia (34°-41°S), Argentina

NASA Astrophysics Data System (ADS)

Folguera, Alicia; Zárate, Marcelo; Tedesco, Ana; Dávila, Federico; Ramos, Victor A.

2015-12-01

The Pampas plain (30°-41°S) has historically been considered as a sector that evolved independently from the adjacent Andean ranges. Nevertheless, the study of the Pampas showed that it is reasonable to expect an important influence from the Andes into the extraandean area. The Pampas plain can be divided into two sectors: the northern portion, adjacent to the Pampean Ranges, has been studied by Davila (2005, 2007, 2010). The southern sector (34°-41°S) is the objective of the present work. The study of this area allowed to characterize two separate foreland basins: the Southern Pampa basin and the Northern Patagonian basin. The infill is composed of Late Miocene and Pliocene units, interpreted as distal synorogenic sequences associated with the late Cenozoic Andean uplift at this latitudinal range. These foreland basins have been defined based on facies changes, distinct depositional styles, along with the analysis of sedimentary and isopach maps. The basins geometries are proposed following De Celles and Gilles (1996) taking into account the infill geometry, distribution and grain size. In both cases, these depocenters are located remarkably far away from the Andean tectonics loads. Therefore they cannot be explained with short-wave subsidence patterns. Elastic models explain the tectonic subsidence in the proximal depocenters but fail to replicate the complete distal basins. These characteristics show that dynamic subsidence is controlling the subsidence in the Southern Pampas and Northern Patagonian basins.

South Atlantic sag basins: new petroleum system components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, S.G.; Mello, M.R.

Newly discovered pre-salt source rocks, reservoirs and seals need to be included as components to the petroleum systems of both sides of the South Atlantic. These new components lie between the pre-salt rift strata and the Aptian salt layers, forming large, post-rift, thermal subsidence sag basins. These are differentiated from the older rift basins by the lack of syn-rift faulting and a reflector geometry that is parallel to the base salt regional unconformity rather than to the Precambrian basement. These basins are observed in deep water regions overlying areas where both the mantle and the crust have been involved inmore » the extension. This mantle involvement creates post-rift subsiding depocenters in which deposition is continuous while proximal rift-phase troughs with little or no mantle involvement are bypassed and failed to accumulate potential source rocks during anoxic times. These features have been recognized in both West African Kwanza Basin and in the East Brasil Rift systems. The pre-salt source rocks that are in the West African sag basins were deposited in lacustrine brackish to saline water environment and are geochemically distinct from the older, syn-rift fresh to brackish water lakes, as well as from younger, post-salt marine anoxic environments of the drift phase. Geochemical analyses of the source rocks and their oils have shown a developing source rock system evolving from isolated deep rift lakes to shallow saline lakes, and culminating with the infill of the sag basin by large saline lakes to a marginally marine restricted gulf. Sag basin source rocks may be important in the South Atlantic petroleum system by charging deep-water prospects where syn-rift source rocks are overmature and the post-salt sequences are immature.« less

Seismic features of Winnipegosis mounds in Saskatchewan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gendzwill, D.J.

1988-07-01

The Winnipegosis Formation of southern Saskatchewan is characterized by reefs or reeflike mounds in its upper member. Several characteristic features of the mounds permit their identification from seismic-reflection data. These features include reflections from the flanks of the mound, a change in the reflection continuity in the middle and base of the mound, a velocity pullup under the mound, and subsidence of strata over the mound. Dissolution of the salt which surrounds the mounds sometimes occurs, resulting in a drape structure. Some or all of these features may be present at the correct seismic stratigraphic level for Winnipegosis mounds, dependingmore » on the local conditions. Subsidence of strata over the mounds indicates compaction and porosity loss from the original mound or possibly the degree of dolomitization or pressure dissolution. Salt-removal features over or adjacent to the mounds indicate fluid movements. Approximate ages can be estimated from stratigraphic thinning and thickening relationships above such features. Complications in identifying Winnipegosis mounds may arise from thin-bed effects if the mounds are not very thick compared to a seismic wavelength. Confusion may also arise from anhydrite, which may encase the mounds or which may form a thick horizontal layer at the tops of the mounds, causing an interfering signal.« less

Post-orogenic subsidence and uplift of the Carpathian belt: An integrated approach

NASA Astrophysics Data System (ADS)

Bertotti, G.; Matenco, L.; Drijkonigen, G.; Krijgsman, W.; Tarapoanca, M.; Panea, I.; Vasiliev, I.; Milea, M.; Cloetingh, S.

2003-04-01

Several hundred metres thick Pliocene to Quaternary sequences outcropping along the Carpathian front steeply dip away from the mountain belt towards the Carpathian foredeep. They overly the Carpathian fold-and-thrust belt and document that, following the main contractional stages, the orogenic wedge first subsided and was then uplifted. Uplift occurred coeval with substantial subsidence in the basin adjacent to the E, the Focsani Depression. To define the precise kinematics of such movements and thereby constrain these vertical movements taking place in the "wrong" place and in the "wrong" time, the Netherlands Research Center for Integrated Solid Earth Science has launched a large campaign of geological and geophysical investigation. The main components of the project are as follows: 1) acquisition of nearly 100km of seismic data designed to image the uppermost hundred metres of the Earth's crust and thereby making a precise connection between features visible in Industry lines and at the surface 2) paleomagnetic investigations in order to constrain the age of the poorly dated continental to lacustrine sediments 3) A seismic experiment designed to detect 3-D effects on 2-D acquisition 4) Structural work to determine the stress/strain conditions during subsidence and subsequent uplift At a larger scale, these activities are embedded in the effort made by ISES and connected groups to precisely constrain the kinematics of the Pannonian-Carpathian system. Seismic acquisition has been performed during the summer 2002 and has been technically very successful thanks also to the effort of the prospecting company Prospectiunii SA. Lines have been processed and are currently being interpreted. The most apparent feature is the lack of localized deformation demonstrating that subsidence and tilting affected areas of several tens of kilometers and are not related to single faults. Sampling for paleomagnetic studies has been carried out in 2002 along the same section where seismic acquisition took place. Preliminary measurements show good analytical results and will therefore produce relevant results in the coming months.

Topography of the overriding plate during progressive subduction: A dynamic model to explain forearc subsidence

NASA Astrophysics Data System (ADS)

Chen, Z.; Schellart, W. P.; Duarte, J. C.; Strak, V.

2017-12-01

Topography that forms at the free top surface of the lithosphere contains important information about the dynamics of the tectonic plates and the sub-lithospheric mantle. Investigating topography around subduction zones can provide quantitative and conceptual insights into the interaction between the plates, the slabs, mantle flow, and the associated stresses. To achieve this, geodynamic modelling can be an effective tool. In this study, we used techniques of stereoscopic photogrammetry and Particle Image Velocimetry to monitor simultaneously the topography of the overriding plate and the velocity field of the subduction-induced mantle flow occurring in the mantle wedge. Model results show that the overriding plate topography is characterized by an area of forearc topographic subsidence, with a magnitude scaling to 1.44-3.97 km in nature, and a transient local topographic high located between the forearc depression and the trench. These topographic features rapidly develop during the slab sinking phase and gradually decrease during the slab rollback phase. We propose that these topographic transient features predominantly result from the variation of the vertical component of the trench suction along the subduction zone interface, which is minimum near the trench and maximum near the tip of the mantle wedge and is caused by the gradual slab steepening during the initial transient slab sinking phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in the formation of the forearc subsidence. Our findings provide a new mechanism for the formation of forearc topographic subsidence, which has been commonly observed at natural subduction zones.

Resolving the Subsidence Anomaly of the East Tasman Plateau Using New Insights from the Cascade Seamount, Southwest Tasman Sea

NASA Astrophysics Data System (ADS)

Vorsanger, S. L.; Scher, H.; Johnson, S.; Mundana, R.; Sauermilch, I.; Duggan, B.; Whittaker, J. M.

2017-12-01

The Cascade Seamount is a wave-planated feature located on the microcontinent of the East Tasman Plateau (ETP). The minimum subsidence rate of the Seamount and the ETP can be estimated by dividing the present-day depth of the wave-cut surface (640 m) by the age of Cascade Seamount basalts as determined by potassium-argon (K-Ar) dating (33.4 and 36 Ma). This approach yields a subsidence rate of 18 m/Myr. However, significantly more rapid subsidence rates of the East Tasman Plateau (ETP) — upon which the Cascade Seamount rests — since the Eocene-Oligocene transition have been proposed utilizing a nearby sediment core, Ocean Drilling Program (ODP) Site 1172. Late Eocene paleodepths determined by Stickley et al. (2004) using sedimentological and biostratigraphic techniques, indicate a subsidence rate of 85 m/Myr for the ETP. These two results present a paradox, which implies that the ETP subsided at a rate greater than the Seamount itself, over the same time interval. It also implies that the seamount formed above sea level. The subsidence ambiguity may be attributed to the presence of a turbidity current deposit in the sediment core, or uncertainty in the age and/or location of the K-Ar dated basalts of the Cascade Seamount. Statistical analysis of the published grain size measurements will be used to test for the presence of a turbidity current deposit in ODP Site 1172. We will also measure 87Sr/86Sr ratios of marine carbonate samples from conglomerates obtained from the Cascade Seamount during the August 2016 RV Investigator voyage (IN2016_E01) to confirm the age of the wave planated surfaces by Strontium Isotope Stratigraphy. This will allow for a more robust calculation for the subsidence of the ETP which was a critical barrier in the Tasmanian Gateway that allowed for the formation of the Antarctic Circumpolar Current.

Subsidence monitoring with geotechnical instruments in the Mexicali Valley, Baja California, Mexico

NASA Astrophysics Data System (ADS)

Glowacka, E.; Sarychikhina, O.; Márquez Ramírez, V. H.; Robles, B.; Nava, F. A.; Farfán, F.; García Arthur, M. A.

2015-11-01

The Mexicali Valley (northwestern Mexico), situated in the southern part of the San Andreas fault system, is an area with high tectonic deformation, recent volcanism, and active seismicity. Since 1973, fluid extraction, from the 1500-3000 m depth range, at the Cerro Prieto Geothermal Field (CPGF), has influenced deformation in the Mexicali Valley area, accelerating the subsidence and causing slip along the traces of tectonic faults that limit the subsidence area. Detailed field mapping done since 1989 (González et al., 1998; Glowacka et al., 2005; Suárez-Vidal et al., 2008) in the vicinity of the CPGF shows that many subsidence induced fractures, fissures, collapse features, small grabens, and fresh scarps are related to the known tectonic faults. Subsidence and fault rupture are causing damage to infrastructure, such as roads, railroad tracks, irrigation channels, and agricultural fields. Since 1996, geotechnical instruments installed by CICESE (Centro de Investigación Ciéntifica y de Educación Superior de Ensenada, B.C.) have operated in the Mexicali Valley, for continuous recording of deformation phenomena. Instruments are installed over or very close to the affected faults. To date, the network includes four crackmeters and eight tiltmeters; all instruments have sampling intervals in the 1 to 20 min range. Instrumental records typically show continuous creep, episodic slip events related mainly to the subsidence process, and coseismic slip discontinuities (Glowacka et al., 1999, 2005, 2010; Sarychikhina et al., 2015). The area has also been monitored by levelling surveys every few years and, since the 1990's by studies based on DInSAR data (Carnec and Fabriol, 1999; Hansen, 2001; Sarychikhina et al., 2011). In this work we use data from levelling, DInSAR, and geotechnical instruments records to compare the subsidence caused by anthropogenic activity and/or seismicity with slip recorded by geotechnical instruments, in an attempt to obtain more information about the process of fault slip associated with subsidence.

Three Hawaiian calderas: An origin through loading by shallow intrusions?

NASA Astrophysics Data System (ADS)

Walker, George P. L.

1988-12-01

The calderas of Kilauea and Mauna Loa are highly dynamic structures, and in the <200-year historic period have varied in volume by a factor of 2, and gained or lost 1 km3 per century. The deeply eroded caldera of the extinct Koolau Volcano in Oahu is wider than active Hawaiian calderas, and its lavas have a strong centripetal dip and funnel structure not evident at Kilauea or Mauna Loa. The differences can be attributed to the different erosion depths, and the time integrated subsidence profile of Kilauea is also a stepped funnel (having its apex at Halemaumau). Koolau caldera is the focus of an extraordinarily intense dike complex, and an intriguing feature is the great diminution in dike concentration into the caldera. It is thought that dike injection in any part of the complex generally continued until it reached 50% to 65%. In outer parts of the caldera, the complex was maintained at or rebuilt to this value despite subsidence. In the center of the caldera (where the positive Bouguer anomaly is centered), subsidence evidently greatly outpaced the capacity of dike injections to rebuild the complex. Assuming the same dike injection rate as Kilauea and Mauna Loa yields a volumetric subsidence rate in Koolau caldera exceeding 1 km3 per century. Hawaiian calderas are much more dynamic than calderas of silicic volcanoes, shaped by frequent small events instead of a few great ones. The temporal and volumetric correspondence of historical subsidence events with eruptions is poor, and this and the high subsidence rates argue for a caldera-forming mechanism that consumes the subsided rocks. It is suggested that subsidence is caused by the great localized excess load of intrusive rocks, carrying the center of the volcano into the thermally weakened lithosphere above the Hawaiian hot spot. It is envisaged that under steady state conditions the magma chamber rises, as the injection of intrusions causes the level of neutral buoyancy (at which the chamber is located) to ascend, and keeps pace with subsidence.

Tectonic evolution of the Paranoá basin: New evidence from gravimetric and stratigraphic data

NASA Astrophysics Data System (ADS)

Martins-Ferreira, Marco Antonio Caçador; Campos, José Eloi Guimarães; Von Huelsen, Monica Giannoccaro

2018-06-01

Field gravimetric and stratigraphic surveys were conducted with the aim to constraint the mechanisms responsible for the initiation of the Stenian-Tonian Paranoá basin, central Brazil, a subject not yet studied in detail. The Paranoá Group crops out in the external zone of the Brasília Belt, a Neoproterozoic orogen in the western margin of the São Francisco Craton. Detailed geological mapping confirmed the existence of a regional scale fault that controlled sedimentation of the Paranoá Group during the deposition of its basal formations, revealing important details about basin initiation and early evolution. Gravimetric modeling indicates the existence of paleorift structures beneath the Paranoá sequence in the study area. Results from both stratigraphic and gravimetric surveys show strong evidence of mechanical subsidence by faulting during basin initiation. Unsorted, angular, clasts cut by quartz veins and brecciated boulders present in the basal conglomerate, support this hypothesis. Basin initiation faults coincide with deeper paleorift faults and are thus interpreted as reactivations of the older Statherian Araí Rift. The reactivations favored an initial regime of mechanical subsidence, dominated by the development of epirogenic arches subsiding at different rates. Apart from faulting activity, the post-basal sequence presents no evidence of rift environment in the strict sense. Besides, the great lateral continuity and relatively constant thickness of facies, indicate that an initial mechanic subsidence rapidly gave way to flexural subsidence during subsequent stages of basin evolution. The Paranoá Group do not present reliable characteristics that would allow its strict classification as a passive margin. Its main stratigraphic characteristics, tectonic location and basement architecture, indicate that the Paranoá Group was deposited in a cratonic margin basin, and may have been either connected to a passive margin basin at times of sea level rise, or evolved to a passive margin later in time.

A method of evolving novel feature extraction algorithms for detecting buried objects in FLIR imagery using genetic programming

NASA Astrophysics Data System (ADS)

Paino, A.; Keller, J.; Popescu, M.; Stone, K.

2014-06-01

In this paper we present an approach that uses Genetic Programming (GP) to evolve novel feature extraction algorithms for greyscale images. Our motivation is to create an automated method of building new feature extraction algorithms for images that are competitive with commonly used human-engineered features, such as Local Binary Pattern (LBP) and Histogram of Oriented Gradients (HOG). The evolved feature extraction algorithms are functions defined over the image space, and each produces a real-valued feature vector of variable length. Each evolved feature extractor breaks up the given image into a set of cells centered on every pixel, performs evolved operations on each cell, and then combines the results of those operations for every cell using an evolved operator. Using this method, the algorithm is flexible enough to reproduce both LBP and HOG features. The dataset we use to train and test our approach consists of a large number of pre-segmented image "chips" taken from a Forward Looking Infrared Imagery (FLIR) camera mounted on the hood of a moving vehicle. The goal is to classify each image chip as either containing or not containing a buried object. To this end, we define the fitness of a candidate solution as the cross-fold validation accuracy of the features generated by said candidate solution when used in conjunction with a Support Vector Machine (SVM) classifier. In order to validate our approach, we compare the classification accuracy of an SVM trained using our evolved features with the accuracy of an SVM trained using mainstream feature extraction algorithms, including LBP and HOG.

Subsidence of topography on Io

NASA Technical Reports Server (NTRS)

Webb, Erik K.; Stevenson, David J.

1987-01-01

The underlying roots of Io's topographic features are softened and eroded by contact with the hot mantle, resulting in a subsidence which is analogous to the progress of a butter pat on a frying pan. This process would be offset by crustal thickening due to continuing volcanism if the rate for this phenomenon were more than the observed 1 cm/year or less. Because the crustal thinning would occur at about 50 cm/year if the material underneath were a pure magma ocean, Io cannot have a global magna ocean, and interior viscosities greater than about 10 to the 10th P are implied.

Multi-sensor technologies for analyzing sinkholes in Hamedan, west Iran

NASA Astrophysics Data System (ADS)

Vajedian, Sanaz; Motagh, Mahdi; Hojati, Ahmad; Wetzel, Hans-Ulrich

2017-04-01

Dissolution of the carbonate beds such as limestone, dolomite or gypsum by acidic groundwater flowing through fractures and joints in the bedrock alters land surface and enhances the development of sinkholes. Sinkhole formation causes the surface to subside or even collapse suddenly without any prior warning, leading to extensive damage and sometimes loss of life and property, in particular in urban areas. Delineating sinkholes is critical for understanding hydrological processes and mitigating geological hazards in karst areas. The recent availability of high-resolution digital elevation models (DEM) from TanDEM-X (TDX) mission enables us to delineate and analyze geomorphologic features and landscape structures at an unprecedented level of details, in comparison to previous missions such as c-band and x-band Shuttle Radar Topography Mission (SRTM). In this study, we develop an adaptive sinkhole-delineating method based on photogrammetry techniques to detect karst sinkholes in Hamedan , west Iran, using TDX-derived DEMs. We apply automatic feature extraction using watershed algorithm in order to detect depression areas. We show that using high-resolution TDX data from different geometries and time periods we could effectively distinguish sinkholes from other depression features of the basin. We also use interferometric synthetic aperture radar (InSAR) technique with SAR data acquired from a variety of sensors including Envisat, ALOS, TerraSAR-X and Sentinel-1 to quantify long-term subsidence in areas prone to sinkhole formation. Our results indicate that the formation of a lot of sinkholes is influenced by land subsidence, affecting the region over 100 km with the maximum rate of 4-5 cm/yr during 2003 to 2016.

Advanced subsidence monitoring using persistent scatterer interferometry for Jharia Coal Field, Dhanbad, India

NASA Astrophysics Data System (ADS)

Thapa, Shailaja; Chatterjee, R. S.; Kumar, Dheeraj; Singh, K. B.; Sengar, Vivek

2017-10-01

This paper presents a spatiotemporal study of surface subsidence over urban area due to coal mining using Persistent scatterer interferometry. In the past few years Differential Interferometric Synthetic Aperture Radar has emerged as a very useful remote sensing technique for measuring land subsidence. It plays a vital role in insitu subsidence prediction of coal mining area. However there are some limitation viz. atmospheric decorrelation, temporal decorrelation and spatial decorrelation with conventional D-InSAR techniques, which can be overcome up to certain extent by using multiinterferogram framework approach. The Persistent Scatterer interferometry technique comprises of more number of SAR datasets, it only concentrates over the pixel which remain coherent over long time period. Persistent Scatterer interferometry makes deformation measurement on permanent scattering location for the targeted ground surface. Mainly, these permanent scatterer are manmade features like metallic bridges, dams, antennae roof of buildings etc. apart that some permanent scatterer may comprise of prominent stable natural targets. The results obtained from PS-InSAR gives more precised measurement of surface deformation. Total eight ALOS PALSAR scenes covering the time period from 2007 to 2010 have been utilized to produce ground deformation map using PSInSAR techniques for Jharia Coal field, Dhanbad. This is proven technique, which helps to identify the persistent land surface movement .The results were analyzed Sijua area in Jharia coalfield. The subsidence fringes were demarcated over the entire study area. The PSInSAR results were validated using precision leveling data provided by mining authorities. The results demonstrates that PSInSAR can be used as potential tool to highlight the subsidence prone area depending upon the spatial and temporal coherency of SAR data.

Groundwater-related Land Deformation over the Mega Aquifer System in Saudi Arabia: Inferences from InSAR, GRACE, Earthquake records, Field, and Spatial Data Analysis.

NASA Astrophysics Data System (ADS)

Othman, A.; Sultan, M.; Becker, R.; Sefry, S.; Alharbi, T.; Alharbi, H.; Gebremichael, E.

2017-12-01

Land deformational features (subsidence, and earth fissures, etc.) are being reported from many locations over the Lower Mega Aquifer System (LMAS) in the central and northern parts of Saudi Arabia. We applied an integrated approach (remote sensing, geodesy, GIS, geology, hydrogeology, and geotechnical) to identify nature, intensity, spatial distribution, and factors controlling the observed deformation. A three-fold approach was adopted to accomplish the following: (1) investigate, identify, and verify the land deformation through fieldwork; (2) assess the spatial and temporal distribution of land deformation and quantify deformation rates using Interferometric Synthetic Aperture Radar (InSAR) and Persistent Scatterer Interferometry (PSI) methods (period: 2003 to 2012); (3) generate a GIS database to host all relevant data and derived products (remote sensing, geology, geotechnical, GPS, groundwater extraction rates, and water levels, etc.) and to correlate these spatial and temporal datasets in search of causal effects. The following observations are consistent with deformational features being caused by excessive groundwater extraction: (1) distribution of deformational features correlated spatially and temporally with increased agricultural development and groundwater extraction, and with the decline in groundwater levels and storage; (2) earthquake events (1.5 - 5.5 M) increased from one event at the beginning of the agricultural development program in 1980 (average annual extraction [ANE]: 1-2 km³/yr), to 13 events per year between 1995 to 2005, the decade that witnessed the largest expansion in groundwater extraction (ANE: >6.4 km³) and land reclamation using groundwater resources; and (3) earthquake epicenters and the deformation sites are found largely within areas bound by the Kahf fault system suggesting that faults play a key role in the deformation phenomenon. Findings from the PSI investigation revealed high, yet irregularly distributed, subsidence rates (-4 to -15 mm/yr) along a NW-SE trending graben within the Wadi As-Sirhan Basin in the northern part of LMAS with the highest subsidence rates being localized within elongated bowls, that are proximal to, or bound by, the major faults and that areas to the east and west of the bounding faults show no, or minimal subsidence.

Gravity study of the Central African Rift system: a model of continental disruption 2. The Darfur domal uplift and associated Cainozoic volcanism

NASA Astrophysics Data System (ADS)

Bermingham, P. M.; Fairhead, J. D.; Stuart, G. W.

1983-05-01

Gravity studies of the Darfur uplift, Western Sudan, show it to be associated with a circular negative Bouguer anomaly, 50 mGal in amplitude and 700 km across. A three-dimensional model interpretation of the Darfur anomaly, using constraints deduced from geophysical studies of similar but more evolved Kenya and Ethiopia domes, suggests either a low-density laccolithic body at mid-lithospheric depth (~ 60 km) or a thinned lithosphere with emplacement at high level of low-density asthenospheric material. The regional setting of the Darfur uplift is described in terms of it being an integral part of the Central African Rift System which is shown to be broadly equivalent to the early to middle Miocene stage in the development of the Afro-Arabian Rift System. Comparisons between these rift systems suggest that extensional tectonics and passive rifting, resulting in the subsiding sedimentary rift basins associated with the Ngaoundere, Abu Gabra, Red Sea and Gulf of Aden rifts, are more typical of the early stage development of passive continental margins than the active domal uplift and development of rifted features associated with the Darfur, Kenya and Ethiopia domes.

Using GPS Imaging to Unravel Vertical Land Motions in the Interior Pacific Northwest

NASA Astrophysics Data System (ADS)

Overacker, J.; Hammond, W. C.; Kraner, M.; Blewitt, G.

2017-12-01

GPS Imaging uses robust trends in time series of GPS positions to create a velocity field that can reveal rates and patterns of vertical motions that would be otherwise difficult to detect. We have constructed an image of vertical land velocities within the interior Pacific Northwest region of the United States using GPS Imaging. The image shows a 50-250 km wide swath of approximately 2 mm/yr of subsidence seemingly unrelated to topographic features of the region. The extent of the signal roughly corresponds to the Juan de Fuca plate subduction latitudes and longitude of the Cascade arc. This suggests that the signal could be associated with ongoing crustal deformation possibly related to plate-scale geodynamic forces arising from interseismic coupling, long term plate boundary tractions, volcanic loading, and/or mantle flow. However, hydrological loading from accumulating precipitation in the Cascades and in the region's groundwater basins, and possible effects from Glacial Isostatic Adjustment (GIA) near its hinge line cannot be discounted as potential contributors to the observed subsidence signal. Here we attempt to unravel the contributions of hydrological loading and GIA to the vertical GPS signal observed within the interior Pacific Northwest. In order to determine the non-tectonic contributions to the observed vertical GPS Image, we will examine how the subsidence rate changes over time using early and late period comparisons. GPS, GRACE, and climatic data will be used in conjunction to disentangle the hydrological effect from the GPS Image. GIA models of the Western Cordillera will be compared with the patterns in the GPS Image to assess whether the signal can be explained with current models of GIA. Our presentation will document the signals, uncertainties, and hypotheses for the possible mechanisms behind this subsidence and attempt to quantify their relation and contribution to the observed deformation signal. Figure 1: Pacific Northwest GPS Imaging result of vertical velocity field plotted over topographic relief map. Red is up, blue is down. GPS station locations are shown in green. Greatest amount of subsidence shown by GPS Imaging appear uncorrelated with topographic features.

Feedback of land subsidence on the movement and conjunctive use of water resources

USGS Publications Warehouse

Schmid, Wolfgang; Hanson, Randall T.; Leake, Stanley A.; Hughes, Joseph D.; Niswonger, Richard G.

2014-01-01

The dependency of surface- or groundwater flows and aquifer hydraulic properties on dewatering-induced layer deformation is not available in the USGS's groundwater model MODFLOW. A new integrated hydrologic model, MODFLOW-OWHM, formulates this dependency by coupling mesh deformation with aquifer transmissivity and storage and by linking land subsidence/uplift with deformation-dependent flows that also depend on aquifer head and other flow terms. In a test example, flows most affected were stream seepage and evapotranspiration from groundwater (ETgw). Deformation feedback also had an indirect effect on conjunctive surface- and groundwater use components: Changed stream seepage and streamflows influenced surface-water deliveries and returnflows. Changed ETgw affected irrigation demand, which jointly with altered surface-water supplies resulted in changed supplemental groundwater requirements and pumping and changed return runoff. This modeling feature will improve the impact assessment of dewatering-induced land subsidence/uplift (following irrigation pumping or coal-seam gas extraction) on surface receptors, inter-basin transfers, and surface-infrastructure integrity.

Geomorphology of coal seam fires

NASA Astrophysics Data System (ADS)

Kuenzer, Claudia; Stracher, Glenn B.

2012-02-01

Coal fires occur in underground natural coal seams, in exposed surface seams, and in coal storage or waste piles. The fires ignite through spontaneous combustion or natural or anthropogenic causes. They are reported from China, India, USA, South Africa, Australia, and Russia, as well as many other countries. Coal fires lead to loss of a valuable resource (coal), the emission of greenhouse-relevant and toxic gases, and vegetation deterioration. A dangerous aspect of the fires is the threat to local mines, industries, and settlements through the volume loss underground. Surface collapse in coal fire areas is common. Thus, coal fires are significantly affecting the evolution of the landscape. Based on more than a decade of experience with in situ mapping of coal fire areas worldwide, a general classification system for coal fires is presented. Furthermore, coal seam fire geomorphology is explained in detail. The major landforms associated with, and induced by, these fires are presented. The landforms include manifestations resulting from bedrock surface fracturing, such as fissures, cracks, funnels, vents, and sponges. Further manifestations resulting from surface bedrock subsidence include sinkholes, trenches, depressions, partial surface subsidence, large surface subsidence, and slides. Additional geomorphologic coal fire manifestations include exposed ash layers, pyrometamorphic rocks, and fumarolic minerals. The origin, evolution, and possible future development of these features are explained, and examples from in situ surveys, as well as from high-resolution satellite data analyses, are presented. The geomorphology of coal fires has not been presented in a systematic manner. Knowledge of coal fire geomorphology enables the detection of underground coal fires based on distinct surface manifestations. Furthermore, it allows judgments about the safety of coal fire-affected terrain. Additionally, geomorphologic features are indicators of the burning stage of fires. Finally, coal fire geomorphology helps to explain landscape features whose occurrence would otherwise not be understood. Although coal fire-induced thermal anomalies and gas release are also indications of coal fire activity, as addressed by many investigators, no assessment is complete without sound geomorphologic mapping of the fire-induced geomorphologic features.

Implications of horsts and grabens on the development of canyons and seismicity on the west africa coast

NASA Astrophysics Data System (ADS)

Ola, Peter S.; Olabode, Solomon O.

2018-04-01

Subsurface basement topography in the Nigerian portion of the Benin Basin has been studied using borehole data of wells drilled to the basement and one strike line of seismic section. Two areas of a sharp drop in topography with a horst in between were observed in the study area. These features were projected to a seismic section in the offshore area of the Benin basin. The result depicts the structural features as horst and grabens coinciding with the Avon platform bounded on the right side by Ise graben, and the Orimedu graben to the left. The observed relationship of the grabens with the present day location of Avon Canyon on the seismic section also suggests an active subsidence along fractured zones. The subsidence, which probably is occurring along similar fracture zones in the Gulf of Guinea, could be responsible for the occasionally reported seismicity on the margin of West Africa. A detailed seismographic study of the fracture zones is recommended.

Sinkholes, subsidence and subrosion on the eastern shore of the Dead Sea as revealed by a close-range photogrammetric survey

NASA Astrophysics Data System (ADS)

Al-Halbouni, Djamil; Holohan, Eoghan P.; Saberi, Leila; Alrshdan, Hussam; Sawarieh, Ali; Closson, Damien; Walter, Thomas R.; Dahm, Torsten

2017-05-01

Ground subsidence and sinkhole collapse are phenomena affecting regions of karst geology worldwide. The rapid development of such phenomena around the Dead Sea in the last four decades poses a major geological hazard to the local population, agriculture and industry. Nonetheless many aspects of this hazard are still incompletely described and understood, especially on the eastern Dead Sea shore. In this work, we present a first low altitude (< 150 m above ground) aerial photogrammetric survey with a Helikite Balloon at the sinkhole area of Ghor Al-Haditha, Jordan. We provide a detailed qualitative and quantitative analysis of a new, high resolution digital surface model (5 cm px-1) and orthophoto of this area (2.1 km2). We also outline the factors affecting the quality and accuracy of this approach. Our analysis reveals a kilometer-scale sinuous depression bound partly by flexure and partly by non-tectonic faults. The estimated minimum volume loss of this subsided zone is 1.83 ṡ 106 m3 with an average subsidence rate of 0.21 m yr-1 over the last 25 years. Sinkholes in the surveyed area are localized mainly within this depression. The sinkholes are commonly elliptically shaped (mean eccentricity 1.31) and clustered (nearest neighbor ratio 0.69). Their morphologies and orientations depend on the type of sediment they form in: in mud, sinkholes have a low depth to diameter ratio (0.14) and a long-axis azimuth of NNE-NE. In alluvium, sinkholes have a higher ratio (0.4) and are orientated NNW-N. From field work, we identify actively evolving artesian springs and channelized, sediment-laden groundwater flows that appear locally in the main depression. Consequently, subrosion, i.e. subsurface mechanical erosion, is identified as a key physical process, in addition to dissolution, behind the subsidence and sinkhole hazard. Furthermore, satellite image analysis links the development of the sinuous depression and sinkhole formation at Ghor Al-Haditha to preferential groundwater flow paths along ancient and current wadi riverbeds.

Barriers and facilitators to healthy eating and disease self-management among older adults residing in subsidized housing.

PubMed

Petroka, Katherine; Campbell-Bussiere, Rania; Dychtwald, Dan K; Milliron, Brandy-Joe

2017-09-01

As adults transition into older ages, meeting age-specific dietary recommendations can become increasingly challenging, especially for low-income seniors who reside in publicly subsidized rental housing. The primary objectives of this study were to: 1) identify barriers and facilitators to healthy eating and self-management of nutrition-related chronic illnesses experienced by low-income seniors residing in a subsidized housing setting; and 2) assess the interest in community nutrition programming among low-income seniors residing in a subsidized housing setting. A qualitative study design, using food focus groups and food pantry observations, was used. Participants included 24 male and female senior adults, between 65 and 75 years of age, residing in a subsidized housing community in Philadelphia, PA. This setting also included the unique features of a community garden and food pantry. Data were manually analyzed using a content analysis approach, which included familiarization, identification of themes, categorization and interpretation; and verified using NVivo 10. Personal barriers, including food cost and accessibility, physical limitations, desire for convenience, and low self-efficacy to change dietary habits, inhibited motivation to change. External barriers in the food environment, including lack of transportation and distance of markets to access fresh produce, were commonly cited; as well as negative influences of the internal environment, such as the presence of vending machines, common cultural cooking and eating practices, and the lack of social cohesion. Facilitators focused on food preparation and recipe adaptation. Participants expressed an interest in learning more about food, nutrition, and health through community-based programming.

Subsidence of residual soils in a karst terrain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drumm, E.C.; Kane, W.F.; Ben-Hassine, J.

1990-06-01

Siting and operating landfills for solid waste disposal in eastern Tennessee that can operate with minimum impact on groundwater is problematic. The operational requirement of thick, excavational soils and the regulatory requirement of a buffer between disposal units and an aquifer result in siting most operating East Tennessee landfills in outcrop areas of the Knox Group. However, the common occurrence of karst terrain and sinkholes in the Knox Group indicates the vulnerability of such sites to rapid groundwater recharge and flow and the potential for subsidence or collapse of soil into bedrock cavities. To address the potential for subsidence ormore » collapse of soils at the East Chestnut Ridge site on the Department of Energy's (DOE) Oak Ridge Reservation (ORR), the following activities and analyses were completed: The locations of karst features on the site were determined by field reconnaissance; several sinkholes were selected for detailed examination; soil boring, sampling, and physical testing were performed in soils located within, adjacent to, and outside of sinkholes to characterize soil strength at various depths; detailed plane surveys were made for 11 sinkholes to measure accurately their dimension and shape for use in determining profile functions for subsidence basins at the site; The stress-deformation response of a typical soil profile overlying a hypothetical bedrock cavity was analyzed numerically for a range of soil thickness and a range of cavity radii. A consistent estimate of the relationship between subsidence basin dimension, soil thickness, and cavity radius has been derived. 30 refs., 41 figs., 7 tabs.« less

Land subsidence along the Delta-Mendota Canal in the northern part of the San Joaquin Valley, California, 2003-10

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin; Solt, Mike

2013-01-01

Extensive groundwater withdrawal from the unconsolidated deposits in the San Joaquin Valley caused widespread aquifer-system compaction and resultant land subsidence from 1926 to 1970—locally exceeding 8.5 meters. The importation of surface water beginning in the early 1950s through the Delta-Mendota Canal and in the early 1970s through the California Aqueduct resulted in decreased pumping, initiation of water-level recovery, and a reduced rate of compaction in some areas of the San Joaquin Valley. However, drought conditions during 1976–77 and 1987–92, and drought conditions and regulatory reductions in surface-water deliveries during 2007–10, decreased surface-water availability, causing pumping to increase, water levels to decline, and renewed compaction. Land subsidence from this compaction has reduced freeboard and flow capacity of the Delta-Mendota Canal, the California Aqueduct, and other canals that deliver irrigation water and transport floodwater. The U.S. Geological Survey, in cooperation with the U.S. Bureau of Reclamation and the San Luis and Delta-Mendota Water Authority, assessed land subsidence in the vicinity of the Delta-Mendota Canal as part of an effort to minimize future subsidence-related damages to the canal. The location, magnitude, and stress regime of land-surface deformation during 2003–10 were determined by using extensometer, Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), spirit leveling, and groundwater-level data. Comparison of continuous GPS, shallow extensometer, and groundwater-level data, combined with results from a one-dimensional model, indicated the vast majority of the compaction took place beneath the Corcoran Clay, the primary regional confining unit. Land-surface deformation measurements indicated that much of the northern portion of the Delta-Mendota Canal (Clifton Court Forebay to Check 14) was fairly stable or minimally subsiding on an annual basis; some areas showed seasonal periods of subsidence and of uplift that resulted in little or no longer-term elevation loss. Many groundwater levels in this northern area did not reach historical lows during 2003–10, indicating that deformation in this region was primarily elastic. Although the northern portion of the Delta-Mendota Canal was relatively stable, land-surface deformation measurements indicated the southern portion of the Delta-Mendota Canal (Checks 15–21) subsided as part of a large subsidence feature centered about 15 kilometers northeast of the Delta-Mendota Canal, south of the town of El Nido. Results of InSAR analysis indicated at least 540 millimeters of subsidence near the San Joaquin River and the Eastside Bypass during 2008–10, which is part of a 3,200 square-kilometer area—including the southern part of the Delta-Mendota Canal—affected by 20 millimeters or more of subsidence during the same period. Calculations indicated that the subsidence rate doubled in 2008 in some areas. The GPS surveys done in 2008 and 2010 confirmed the high subsidence rate measured by using InSAR for the same period. Water levels in many shallow and deep wells in this area declined during 2007–10; water levels in many deep wells reached historical lows, indicating that subsidence measured during this period was largely inelastic. InSAR-derived subsidence maps for various periods during 2003–10 showed that the area of maximum active subsidence (that is, the largest rates of subsidence) shifted from its historical (1926–70) location southwest of Mendota to south of El Nido. Continued groundwater-level and land-subsidence monitoring in the San Joaquin Valley is important because (1) regulatory- and drought-related reductions in surface-water deliveries since 1976 have resulted in increased groundwater pumping and associated land subsidence, and (2) land use and associated groundwater pumping continue to change throughout the valley. The availability of surface water remains uncertain; even during record-setting precipitation years, such as 2010–11, water deliveries have fallen short of requests and groundwater pumping was required to meet the irrigation demand. Due to the expected continued demand for irrigation supply water and the limitations and uncertainty of surface-water supplies, groundwater pumping and associated land subsidence is likely to continue in the future. Spatially detailed information on land subsidence is needed to facilitate minimization of future subsidence-related damages to the Delta-Mendota Canal and other infrastructure in the San Joaquin Valley. The integration of subsidence, deformation, and water-level measurements—particularly continuous measurements—enables the analysis of aquifer-system response to increased groundwater pumping, which in turn, enables identification of the preconsolidation head and calculation of aquifer-system storage properties. This information can be used to improve numerical model simulations of groundwater flow and aquifer-system compaction and allow for consideration of land subsidence in the evaluation of water-resource management alternatives.

Somma-Vesuvius ground deformation over the last glacial cycle

NASA Astrophysics Data System (ADS)

Marturano, Aldo; Aiello, Giuseppe; Barra, Diana

2013-04-01

Vertical ground movements at Somma-Vesuvius during the last glacial cycle have been inferred from micropalaeontological and petrochemical analyses of rock samples from boreholes drilled at the archaeological sites of Herculaneum and Pompeii as well as on the apron of the volcano and the adjacent Sebeto and Sarno Valleys. Opposing movements occurred during the periods preceding and following the Last Glacial Maximum (LGM). The uplift began 20 ka ago with marine deposits rising several tens of metres up to 25 m a.s.l., recovering previous subsidence which occurred during the Late glacial period, suggesting a strict connection between volcano-tectonic and glacial cycles. Here we present the analysis of deposits predating the LGM, which confirms subsidence of the Campanian Plain where Mt. Somma-Vesuvius is located, shows variable surface loading effects and highlights the volcano-tectonic stages experienced by the volcano. The self-balancing mechanism of the volcanic system, evolving towards an explosive, subaerial activity 60 ka ago, is testified to by a large ground oscillation in phase with sea level change during the last glacial cycle.

Geology and evolution of lakes in north-central Florida

USGS Publications Warehouse

Kindinger, J.L.; Davis, J.B.; Flocks, J.G.

1999-01-01

Fluid exchange between surficial waters and groundwater in karst environments, and the processes that control exchange, are of critical concern to water management districts and planners. High-resolution seismic data were collected from 30 lakes of north-central Florida. In each case study, lake structure and geomorphology were controlled by solution and/or mechanical processes. Processes that control lake development are twofold: (1) karstification or dissolution of the underlying limestone, and (2) the collapse, subsidence, or slumping of overburden to form sinkholes. Initial lake formation is directly related to the karst topography of the underlying host limestone. Case studies have shown that lakes can be divided by geomorphic types into progressive developmental phases: (1) active subsidence or collapse phase (young); (2) transitional phase (middle age); (3) baselevel phase (mature); and (4) polje (drowned prairie) - broad flat-bottom that have one or all phases of sinkhole. Using these criteria, Florida lakes can be classified by size, fill, subsurface features, and geomorphology.Fluid exchange between surficial waters and groundwater in karst environments, and the processes that control exchange, are of critical concern to water management districts and planners. High-resolution seismic data were collected from 30 lakes of north-central Florida. In each case study, lake structure and geomorphology were controlled by solution and/or mechanical processes. Processes that control lake development are twofold: (1) karstification or dissolution of the underlying limestone, and (2) the collapse, subsidence, or slumping of overburden to form sinkholes. Initial lake formation is directly related to the karst topography of the underlying host limestone. Case studies have shown that lakes can be divided by geomorphic types into progressive developmental phased: (1) active subsidence or collapse phase (young); (2) transitional phase (middle age); (3) baselevel phase (mature); and (4) polje (drowned prairie) - broad flat-bottom that have one or all phases of sinkhole. Using these criteria, Florida lakes can be classified by size, fill, subsurface features, and geomorphology.

Vertical forearc tectonic displacements offer insights into underlying interplate thrust zone processes: 104-105 yr uplift/subsidence cycles in Southwest Pacific arcs may represent recoverable plastic deformation that is often falsely attributed to other causes

NASA Astrophysics Data System (ADS)

Taylor, F. W.; Lavier, L. L.; Frohlich, C.; Thirumalai, K.; Papabatu, A. K.

2015-12-01

In the forearcs of subduction zones, the characteristics of both short-term (temporary earthquake cycle) and longer-term permanent vertical deformation offer insights into processes by which plates subduct. But permanent vertical deformation may be a product of several simultaneous processes, including tectonic erosion/underplating, changing dip of the slab, upward displacement due to buoyancy or bathymetric features, and plastic shortening/extension of the forearc wedge. Here we note the rarely recognized, but possibly common, phenomenon of intermediate time scale transient vertical movements (TVM's). Both the central New Hebrides and Western Solomon forearcs have uplifted ≥500 m over time scales of 105 yr. Uplift started abruptly (over ≤10 ky) and proceeded at localized rates up to 7-8 mm/yr. Both initial uplifts terminated preceding rapid subsidence of similar dimensions and rates that, in turn, had followed yet older uplift. However, these uplifts and subsidences are superimposed on a yet longer-term trend of uplift on time scales >105 yr. The most recent uplifts extended 100-200 km along-arc and 60-90 km cross-arc while plate convergence was <10 km. These 105 yr vertical oscillations are most likely due to plastic shortening/extension driven by strong horizontal forces related to rugged seafloor bathymetry impinging on the outer forearc. Subsidence follows uplift when horizontal force abates temporarily and uplift is no longer supported by enhanced interplate coupling. Over the 105 yr time frame when interplate slip is <10 km, it is difficult to account for the timing, geography, and amounts of up and down motion by processes such as buoyancy or volumetric displacement of downgoing bathymetric features or by tectonic underplating/erosion. Instead, ~1% of shortening within the upper plate is sufficient to account for up to several hundred m of uplift across a large area of the forearc.

Family Child Care Home Education Network

ERIC Educational Resources Information Center

Russom, Dianne

2006-01-01

This article features the Family Child Care Home Education Network (FCCHEN), a groundbreaking program operated by the Riverside County Office of Education's Division of Children and Family Services. The FCCHEN is a network of family child care homes located throughout the Coachella Valley that receive funding for subsidized child care through an…

Reconstructing the internal structure and long-term evolution of hazardous sinkholes combining trenching, electrical resistivity imaging (ERI) and ground penetrating radar (GPR)

NASA Astrophysics Data System (ADS)

Fabregat, Ivan; Gutiérrez, Francisco; Roqué, Carles; Comas, Xavier; Zarroca, Mario; Carbonel, Domingo; Guerrero, Jesús; Linares, Rogelio

2017-05-01

The approaches aimed at characterising specific damaging sinkholes have received limited attention compared with other ground instability phenomena (e.g. landslides). Moreover, the practicality of the trenching technique in combination with numerical dating and retro-deformation analysis for sinkhole site-investigations has been barely explored. This work illustrates the advantages of combining geomorphic mapping, electrical resistivity imaging (ERI), ground penetrating radar (GPR) and trenching for sinkhole characterisation and shows how the trenching technique contributes to fill significant gaps that neither geomorphic nor geophysical methods can address. Two large sinkholes (> 200 m long) related to the interstratal karstification of evaporites and generated by contrasting subsidence mechanisms (sagging, collapse) were investigated in the Fluvia Valley, NE Spain. Although GPR data may provide high resolution information on subsidence-related stratigraphic and structural features at shallow depth, the profiles acquired in the investigated sites with 100 MHz shielded and 40 MHz unshielded antennae provided limited insight into the internal geometry of the sinkholes due to reduced signal penetration related to the presence of conductive clayey material. The ERI sections satisfactorily imaged the general geometry of the sagging and collapse subsidence structures up to depths higher than 100 m and clearly captured the basal contact of the low-resistivity sinkhole fill in the sections with adequate layout and resolution. The trenches, despite their limited depth (ca. 5 m) allowed us to obtain valuable objective information on several key aspects of the subsidence phenomenon: (1) mechanisms (deformation style) and kinematics (progressive versus episodic); (2) limits of ground deformation; (3) temporal evolution (expansion versus contraction); (4) chronology and timing of most recent deformation phase; (5) rates of subsidence and sedimentation; and (6) the role played by subsidence in the development of lacustrine environments and the associated sedimentation patterns.

Identification, prediction, and mitigation of sinkhole hazards in evaporite karst areas

USGS Publications Warehouse

Gutierrez, F.; Cooper, A.H.; Johnson, K.S.

2008-01-01

Sinkholes usually have a higher probability of occurrence and a greater genetic diversity in evaporite terrains than in carbonate karst areas. This is because evaporites have a higher solubility and, commonly, a lower mechanical strength. Subsidence damage resulting from evaporite dissolution generates substantial losses throughout the world, but the causes are only well understood in a few areas. To deal with these hazards, a phased approach is needed for sinkhole identification, investigation, prediction, and mitigation. Identification techniques include field surveys and geomorphological mapping combined with accounts from local people and historical sources. Detailed sinkhole maps can be constructed from sequential historical maps, recent topographical maps, and digital elevation models (DEMs) complemented with building-damage surveying, remote sensing, and high-resolution geodetic surveys. On a more detailed level, information from exposed paleosubsidence features (paleokarst), speleological explorations, geophysical investigations, trenching, dating techniques, and boreholes may help in investigating dissolution and subsidence features. Information on the hydrogeological pathways including caves, springs, and swallow holes are particularly important especially when corroborated by tracer tests. These diverse data sources make a valuable database-the karst inventory. From this dataset, sinkhole susceptibility zonations (relative probability) may be produced based on the spatial distribution of the features and good knowledge of the local geology. Sinkhole distribution can be investigated by spatial distribution analysis techniques including studies of preferential elongation, alignment, and nearest neighbor analysis. More objective susceptibility models may be obtained by analyzing the statistical relationships between the known sinkholes and the conditioning factors. Chronological information on sinkhole formation is required to estimate the probability of occurrence of sinkholes (number of sinkholes/km2 year). Such spatial and temporal predictions, frequently derived from limited records and based on the assumption that past sinkhole activity may be extrapolated to the future, are non-corroborated hypotheses. Validation methods allow us to assess the predictive capability of the susceptibility maps and to transform them into probability maps. Avoiding the most hazardous areas by preventive planning is the safest strategy for development in sinkhole-prone areas. Corrective measures could be applied to reduce the dissolution activity and subsidence processes. A more practical solution for safe development is to reduce the vulnerability of the structures by using subsidence-proof designs. ?? 2007 Springer-Verlag.

Mesozoic evolution of northeast African shelf margin, Libya and Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aadland, R.K.; Schamel, S.

1989-03-01

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. The 250 km-wide and highly differentiated Mesozoic passive margin in the Western Desert region of Egypt is developed above a broad northwest-trending Late Carboniferous basement arch. In northeastern Libya, in contrast, the passive margin is restricted to just the northernmost Cyrenaica platform, where subsidence was extremely rapid in the Jurassic and Early Cretaceous. The boundary between the Western Desertmore » basin and the Cyrenaica platform is controlled by the western flank of the basement arch. In the middle Cretaceous (100-90 Ma), subsidence accelerated over large areas of the Western desert, further enhancing a pattern of east-west-trending subbasins. This phase of rapid subsidence was abruptly ended about 80 Ma by the onset of structural inversion that uplifted the northern Cyrenaica shelf margin and further differentiated the Western Desert subbasin along a northeasterly trend.« less

Basin-centered asperities in great subduction zone earthquakes: A link between slip, subsidence, and subduction erosion?

USGS Publications Warehouse

Wells, R.E.; Blakely, R.J.; Sugiyama, Y.; Scholl, D. W.; Dinterman, P.A.

2003-01-01

Published areas of high coseismic slip, or asperities, for 29 of the largest Circum-Pacific megathrust earthquakes are compared to forearc structure revealed by satellite free-air gravity, bathymetry, and seismic profiling. On average, 71% of an earthquake's seismic moment and 79% of its asperity area occur beneath the prominent gravity low outlining the deep-sea terrace; 57% of an earthquake's asperity area, on average, occurs beneath the forearc basins that lie within the deep-sea terrace. In SW Japan, slip in the 1923, 1944, 1946, and 1968 earthquakes was largely centered beneath five forearc basins whose landward edge overlies the 350??C isotherm on the plate boundary, the inferred downdip limit of the locked zone. Basin-centered coseismic slip also occurred along the Aleutian, Mexico, Peru, and Chile subduction zones but was ambiguous for the great 1964 Alaska earthquake. Beneath intrabasin structural highs, seismic slip tends to be lower, possibly due to higher temperatures and fluid pressures. Kilometers of late Cenozoic subsidence and crustal thinning above some of the source zones are indicated by seismic profiling and drilling and are thought to be caused by basal subduction erosion. The deep-sea terraces and basins may evolve not just by growth of the outer arc high but also by interseismic subsidence not recovered during earthquakes. Basin-centered asperities could indicate a link between subsidence, subduction erosion, and seismogenesis. Whatever the cause, forearc basins may be useful indicators of long-term seismic moment release. The source zone for Cascadia's 1700 A.D. earthquake contains five large, basin-centered gravity lows that may indicate potential asperities at depth. The gravity gradient marking the inferred downdip limit to large coseismic slip lies offshore, except in northwestern Washington, where the low extends landward beneath the coast. Transverse gravity highs between the basins suggest that the margin is seismically segmented and could produce a variety of large earthquakes. Published in 2003 by the American Geophysical Union.

Subsidence monitoring network: an Italian example aimed at a sustainable hydrocarbon E&P activity

NASA Astrophysics Data System (ADS)

Dacome, M. C.; Miandro, R.; Vettorel, M.; Roncari, G.

2015-11-01

According to the Italian law in order to start-up any new hydrocarbon exploitation activity, an Environmental Impact Assessment study has to be presented, including a monitoring plan, addressed to foresee, measure and analyze in real time any possible impact of the project on the coastal areas and on those ones in the close inland located. The occurrence of subsidence, that could partly be related to hydrocarbon production, both on-shore and off-shore, can generate great concern in those areas where its occurrence may have impacts on the local environment. ENI, following the international scientific community recommendations on the matter, since the beginning of 90's years, implemented a cutting-edge monitoring network, with the aim to prevent, mitigate and control geodynamics phenomena generated in the activity areas, with a particular attention to conservation and protection of environmental and territorial equilibrium, taking care of what is known as "sustainable development". The current ENI implemented monitoring surveys can be divided as: - Shallow monitoring: spirit levelling surveys, continuous GPS surveys in permanent stations, SAR surveys, assestimeter subsurface compaction monitoring, ground water level monitoring, LiDAR surveys, bathymetrical surveys. - Deep monitoring: reservoir deep compaction trough radioactive markers, reservoir static (bottom hole) pressure monitoring. All the information, gathered through the monitoring network, allow: 1. to verify if the produced subsidence is evolving accordingly with the simulated forecast. 2. to provide data to revise and adjust the prediction compaction models 3. to put in place the remedial actions if the impact exceeds the threshold magnitude originally agreed among the involved parties. ENI monitoring plan to measure and monitor the subsidence process, during field production and also after the field closure, is therefore intended to support a sustainable field development and an acceptable exploitation programme in which the actual risk connected with the field production is evaluated in advance, shared and agreed among all the involved subjects: oil company, stakeholders and local community (with interests in the affected area).

Magma mixing during caldera forming eruptions

NASA Astrophysics Data System (ADS)

Kennedy, B.; Jellinek, M.; Stix, J.

2006-12-01

During explosive caldera-forming eruptions magma erupts through a ring dyke. Flow is driven, in part, by foundering of a magma chamber roof into underlying buoyant magma. One intriguing and poorly understood characteristic of deposits from calderas is that bulk ignimbrite, pumices, and crystals can show complex stratigraphic zonation. We propose that zonation patterns can be explained by different, and temporally evolving subsidence styles, and that the geometry imposed by subsidence can affect flow and cause mixing in the chamber and ring dyke. We use two series of laboratory experiments to investigate aspects of the mixing properties of flow in the chamber and ring dike during caldera collapse. In the first series, cylindrical blocks of height, h, and diameter, d, are released into circular analog magma chambers of diameter D and height H, containing buoyant fluids with viscosities that we vary. Subsidence occurs as a result of flow through the annular gap (ring dike) between the block and the wall of the surrounding tank of width, w = D-d. Three dimensionless parameters characterize the nature and evolution of the subsidence, and the resulting flow: A Reynolds number, Re, a tilt number, T = w/h and a subsidence number, S = w/H. Whereas Re indicates the importance of inertia for flow and mixing, T and S are geometric parameters that govern the extent of roof tilting, the spatial variation in w during collapse and the wavelength and structure of fluid motions. On the basis of field observations and theoretical arguments we fix T ≍ 0.14 and characterize subsidence and the corresponding flow over a wide range of Re - S parameter space appropriate to silicic caldera systems. Where S < 2 and Re < 103 the roof can rotate or tilt as it sinks and a spectrum of fluid mechanical behavior within the ring dike are observed. The combination of roof rotation and tilting drives unsteady, 3D overturning motions within the ring dike that are inferred to cause extensive mixing. In the absence of tilting and rotation flow is quasi-steady, there is negligible overturning and mixing. Where S > 2 and Re < 10^1 there is a "locking regime" in which the roof the roof rotates as it sinks but does not settle to the floor. The resulting flow leads to little overturning and mixing. Where S > 2 and Re > 10^1 the roof block settles with negligible tilting. Unsteady laminar overturning (Re < 102) and turbulent motions (Re > 103) produce extensive mixing in the ring dike. In a second series of experiments, motivated by the "piecemeal" collapse of many calderas, we investigate additional effects arising in the presence of two blocks. In contrast to the single-block case, the relative motions of the blocks cause extensive overturning and mixing in the chamber as well as the ring dike. Our experimental results are applied to understand the subsidence behavior and the mixing properties of a number of natural cases. Our work suggests that during most caldera-forming eruptions mixing is an inevitable consequence of synchronous eruption and subsidence. In addition, extensive mechanical mixing within the ring dike can explain the cumulate and mingled textures characteristic of many ring dikes.

Moisture controls decomposition rate in thawing tundra

Treesearch

C.E. Hicks-Pries; E.A.G. Schuur; S.M. Natali; J.G. Vogel

2013-01-01

Permafrost thaw can affect decomposition rates by changing environmental conditions and litter quality. As permafrost thaws, soils warm and thermokarst (ground subsidence) features form, causing some areas to become wetter while other areas become drier. We used a common substrate to measure how permafrost thaw affects decomposition rates in the surface soil in a...

ER-2 Doppler Radar (EDOP) Investigations of the Eyewall of Hurricane Bonnie CAMEX-3

NASA Technical Reports Server (NTRS)

Heymsfield, G. M.; Halverson, J.; Simpson, J.; Tian, L.; Bui, P.; Einaudi, Franco (Technical Monitor)

2000-01-01

A persistent, mesoscale region of intense eyewall convection contained within Hurricane Bonnie on 23 August 1998 is examined from multiple observations synthesized from the NASA ER-2 and DC-8 aircraft. The intense convection occurred late in the day as Bonnie was attaining its minimum central pressure and during a stage when the inner core featured a markedly asymmetric structure. The main purpose of this paper is to describe the internal structure of a convective burst and its relationship to the warm core using a synthesis of high-resolution satellite, aircraft radar, and in situ data. An exceptionally vigorous eyewall tower penetrating to nearly 18 km is described. A second intense eyewall tower, adjacent to the eye, is shown to be associated with a mesoscale subsiding current of air that extends horizontally nearly 20 km into the eye interior. The subsidence occupies a substantial depth within the eye and appears to be a much larger scale feature than the convectively-induced, symmetric overturning which commonly occurs on the upper-level flanks of convective towers in other tropical environments.

Vertical Motions of Oceanic Volcanoes

NASA Astrophysics Data System (ADS)

Clague, D. A.; Moore, J. G.

2006-12-01

Oceanic volcanoes offer abundant evidence of changes in their elevations through time. Their large-scale motions begin with a period of rapid subsidence lasting hundreds of thousands of years caused by isostatic compensation of the added mass of the volcano on the ocean lithosphere. The response is within thousands of years and lasts as long as the active volcano keeps adding mass on the ocean floor. Downward flexure caused by volcanic loading creates troughs around the growing volcanoes that eventually fill with sediment. Seismic surveys show that the overall depression of the old ocean floor beneath Hawaiian volcanoes such as Mauna Loa is about 10 km. This gross subsidence means that the drowned shorelines only record a small part of the total subsidence the islands experienced. In Hawaii, this history is recorded by long-term tide-gauge data, the depth in drill holes of subaerial lava flows and soil horizons, former shorelines presently located below sea level. Offshore Hawaii, a series of at least 7 drowned reefs and terraces record subsidence of about 1325 m during the last half million years. Older sequences of drowned reefs and terraces define the early rapid phase of subsidence of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Volcanic islands, such as Maui, tip down toward the next younger volcano as it begins rapid growth and subsidence. Such tipping results in drowned reefs on Haleakala as deep as 2400 m where they are tipped towards Hawaii. Flat-topped volcanoes on submarine rift zones also record this tipping towards the next younger volcano. This early rapid subsidence phase is followed by a period of slow subsidence lasting for millions of years caused by thermal contraction of the aging ocean lithosphere beneath the volcano. The well-known evolution along the Hawaiian chain from high to low volcanic island, to coral island, and to guyot is due to this process. This history of rapid and then slow subsidence is interrupted by a period of minor uplift lasting a few hundred thousand years as the island migrates over a broad flexural arch related to isostatic compensation of a nearby active volcano. The arch is located about 190±30 km away from the center of volcanic activity and is also related to the rejuvenated volcanic stage on the islands. Reefs on Oahu that are uplifted several tens of m above sea level are the primary evidence for uplift as the islands over-ride the flexural arch. At the other end of the movement spectrum, both in terms of magnitude and length of response, are the rapid uplift and subsidence that occurs as magma is accumulated within or erupted from active submarine volcanoes. These changes are measured in days to years and are of cm to m variation; they are measured using leveling surveys, tiltmeters, EDM and GPS above sea level and pressure gauges and tiltmeters below sea level. Other acoustic techniques to measure such vertical movement are under development. Elsewhere, evidence for subsidence of volcanoes is also widespread, ranging from shallow water carbonates on drowned Cretaceous guyots, to mapped shoreline features, to the presence of subaerially-erupted (degassed) lavas on now submerged volcanoes. Evidence for uplift is more limited, but includes makatea islands with uplifted coral reefs surrounding low volcanic islands. These are formed due to flexural uplift associated with isostatic loading of nearby islands or seamounts. In sum, oceanic volcanoes display a long history of subsidence, rapid at first and then slow, sometimes punctuated by brief periods of uplift due to lithospheric loading by subsequently formed nearby volcanoes.

Traces of warping subsided tectonic blocks on Miranda, Enceladus, Titan

NASA Astrophysics Data System (ADS)

Kochemasov, G.

2007-08-01

Icy satellites of the outer Solar system have very large range of sizes - from kilometers to thousands of kilometers. Bodies less than 400-500 km across have normally irregular shapes , often presenting simple Plato's polyhedrons woven by standing inertiagravity waves (see an accompanying abstract of Kochemasov). Larger bodies with enhanced gravity normally are rounded off and have globular shapes but far from ideal spheres. This is due to warping action of inertia-gravity waves of various wavelengths origin of which is related to body movements in elliptical keplerian orbits with periodically changing accelerations (alternating accelerations cause periodically changing forces acting upon a body what means oscillations of its spheres in form of standing warping waves). The fundamental wave 1 and its first overtone wave 2 produce ubiquitous tectonic dichotomy - two segmental structure and tectonic sectoring superimposed on this dichotomy. Two kinds of tectonic blocks (segments and sectors) are formed: uplifted (+) and subsided (-). Uplifting means increasing planetary radius of blocks, subsiding - decreasing radius (as a sequence subsiding blocks diminishing their surfaces must be warped, folded, wrinkled; uplifting blocks increasing their surfaces tend to be deeply cracked, fallen apart). To level changing angular momenta of blocks subsided areas are filled with denser material than uplifted ones (one of the best examples is Earth with its oceanic basins filled with dense basalts and uplifted continents built of less dense on average andesitic material). Icy satellites follow the same rule. Their warped surfaces show differing chemistries or structures of constructive materials. Uplifted blocks are normally built with light (by color and density) water ice. Subsided blocks - depressions, "seas', "lakes", coronas - by somewhat denser material differing in color from water ice (very sharply - Iapetus, moderately - Europa, slightly - many saturnian satellites). A very sharp difference between uplifted and subsided blocks presents Miranda having very sharp relief range. Subsided areas (coronas) are strongly folded, uplifted areas strongly degassed what was witnessed by numerous craters of various sizes (not all craters are of impact origin!). Coronas on Miranda present subsided segment and sectors. Typical is a very sharp boundary between risen (+) and fallen (-) blocks. On Enceladus the subsided (squeezed) southern pole area is characterized by "tiger stripes" - traces of contraction, young ice deposits and famous ejections of water vapor and ice. The squeezed area expels 'molten" material from interior - compare with periodically active Hawaiian volcano expelling basalts from constantly under contraction Pacific basin interior. As to the subsided Pacific basin, it is antepodean to uplifted deeply cracked and degassing Africa. On Enceladus to contracted south is opposed expanded north where past degassing is witnessed by numerous craters (not all of them are impacts!). Contraction traces are very impressive on subsided Titan's surfaces - methane filled thinly folded huge areas mainly in near equatorial regions (some scientists think that these folds are eolian dunes but they are parallel, not perpendicular to presumed winds and, besides, winds below ˜60 km in Titan's atmosphere are not detected by "Huygens") [1, 2]. This methane rich area of intensive folding is antepodean to the uplifted and mainly composed of water ice region Xanadu cut by numerous tectonically controlled dry "valleys". So, in spite of many varieties of surface features on icy satellites of the outer Solar system a common main tectonic tendency exists: opposition of subsided contracted and uplifted expanded blocks. References: [1] Kochemasov G.G. (2006)Titan's radar images: crosscutting ripples are dunes or warping surface waves?// Berlin, 22-26 Sept. 2006, EUROPLANET Sci. Conf. 1, EPSC2006-A-00045. [2] Kochemasov G.G. (2006)Planetary plains: subsidence and warping // Ibid., EPSC2006-A-00018.

Far-Field and Middle-Field Vertical Velocities Associated with Megathrust Earthquakes

NASA Astrophysics Data System (ADS)

Fleitout, L.; Trubienko, O.; Klein, E.; Vigny, C.; Garaud, J.; Shestakov, N.; Satirapod, C.; Simons, W. J.

2013-12-01

The recent megathrust earthquakes (Sumatra, Chili and Japan) have induced far-field postseismic subsidence with velocities from a few mm/yr to more than 1cm/yr at distances from 500 to 1500km from the earthquake epicentre, for several years following the earthquake. This subsidence is observed in Argentina, China, Korea, far-East Russia and in Malaysia and Thailand as reported by Satirapod et al. ( ASR, 2013). In the middle-field a very pronounced uplift is localized on the flank of the volcanic arc facing the trench. This is observed both over Honshu, in Chile and on the South-West coast of Sumatra. In Japan, the deformations prior to Tohoku earthquake are well measured by the GSI GPS network: While the East coast was slightly subsiding, the West coast was raising. A 3D finite element code (Zebulon-Zset) is used to understand the deformations through the seismic cycle in the areas surrounding the last three large subduction earthquakes. The meshes designed for each region feature a broad spherical shell portion with a viscoelastic asthenosphere. They are refined close to the subduction zones. Using these finite element models, we find that the pattern of the predicted far-field vertical postseismic displacements depends upon the thicknesses of the elastic plate and of the low viscosity asthenosphere. A low viscosity asthenosphere at shallow depth, just below the lithosphere is required to explain the subsidence at distances from 500 to 1500km. A thick (for example 600km) asthenosphere with a uniform viscosity predicts subsidence too far away from the trench. Slip on the subduction interface is unable tot induce the observed far-field subsidence. However, a combination of relaxation in a low viscosity wedge and slip or relaxation on the bottom part of the subduction interface is necessary to explain the observed postseismic uplift in the middle-field (volcanic arc area). The creep laws of the various zones used to explain the postseismic data can be injected in models predicting deformations through the whole seismic cycle. In the far-field, the uplift compensating the postseismic subsidence occurs at a rather moderate rate. In the middle field, a slight subsidence or a velocity close to zero is expected on the subduction side of the volcanic arc while uplift is expected on the continent side of the arc. This is in good agreement with the pattern of vertical velocities observed in Northern Honshu previous to Tohoku earthquake.

Recommendations to Sustain the Academic Mission Ecosystem at U.S. Medical Schools.

PubMed

Kerschner, Joseph E; Hedges, Jerris R; Antman, Karen; Abraham, Edward; Colón Negrón, Edgar; Jameson, J Larry

2018-07-01

Academic medical center (AMC) faculty, administrators, and leaders have the critical tasks of teaching and training the next generation of health care providers and biomedical researchers, as well as generating new knowledge that improves the health of all. In the United States, medical schools and their affiliated hospitals train remarkably high-quality physicians and scientists, and the research conducted at these institutions results in advances in health. To that end, AMCs have become essential engines for driving better health in the United States and the rest of the world; they also have become essential engines driving the economies of their respective communities and regions. The education and research missions, however, require subsidization because tuition and extramural grant funding do not cover the costs of these endeavors. This subsidization largely has come from revenues generated by AMCs' clinical endeavors. The viability of this cross-subsidization, however, is increasingly threatened in the current clinical environment. The authors of this Perspective discuss these issues in depth and provide some concrete recommendations to address these challenges. They hope to stimulate discussion and, ultimately, ensure the financial viability of U.S. AMCs-a national resource of utmost importance. Recommendations to sustain research include creating strategic biomedical research plans, developing a defined and sustained model to support National Institutes of Health funding that keeps pace with inflation, and evolving funding mechanisms. Recommendations to sustain medical education include limiting student debt, creating more cost-effective curricula, and ensuring that clinical training opportunities that meet national standards are available to students.

Environmental geology, Allegheny County and vicinity, Pennsylvania; description of a program and its results

USGS Publications Warehouse

Briggs, Reginald Peter

1977-01-01

Past land-use practices, including mining, in Allegheny County, Pa., have resulted in three principal environmental problems, exclusive of air and water contamination. They are flooding, landsliding, and subsidence over underground mines. In 1973, information was most complete relative to flooding and least complete relative to landsliding. Accordingly, in July 1973, the U.S. Geological Survey (USGS) and The Appalachian Regional Commission (ARC) entered into an agreement by which the USGS undertook studies chiefly aimed at increasing knowledge of landsliding and mine subsidence relative to land use, but having other ramifications as well, as part of a larger ARC 'Land-use and physical-resource analysis' (LUPRA) program. The chief geographic focus was Allegheny County, but adjacent areas were included in some investigations. Resulting products, exclusive of this report, are: 1. Forty-three provisional maps of landslide, distribution and susceptibility and of land modified by man in Allegheny County, 1:24,000 scale, 7? -minute quadrangle format, released to open files. 2. Four USGS Miscellaneous Field Studies (MF) maps of Allegheny County showing (a) bedrock, MF685A; (b) susceptibility to landsliding, MF-685B ; (c) coal-mining features, MF-685C; and (d) zones that can be affected by flooding, landsliding and undermining, MF-685D; all at the scale of 1:50,000. 3. Two MF maps showing coal-mining activity and related information and sites of recorded mine-subsidence events, and one MF map classifying land surface by relative potentiality of mine subsidence, in Allegheny, Washington, and Westmoreland Counties, Pa., at a scale of 1:125,000--MF-693A through MF-693C. 4. A companion report to the Allegheny County map of susceptibility to landsliding--USGS Circular 728. 5. Five MF maps, largely in chart form, describing interaction of the shallow ground-water regime with mining-related problems, landsliding, heavy storm precipitation, and other features and processes, largely in Allegheny County--MF-641A through MF-641E. Map products are directly applicable to general classification of land for susceptibility to landsliding and mine subsidence and, to a lesser extent, flooding and engineering characteristics. The hydrogeologic charts enable greater understanding of environmental effects of ground water. All products are guides to expected conditions, but none are substitutes for detailed investigations of specific sites by competent technical personnel on the ground. Specific results and findings are: 1. Knowledge of .susceptibility to landsliding in Allegheny County now is adequate for application to countywide land-use planning. 2. About 110 mi2 (285. km2), or 15 percent, of the county has some significant degree of susceptibility to landsliding. 3. Although a general classification of land in Allegheny, Washington, and Westmoreland Counties relative to mine-subsidence incidents was prepared, data are wholly inadequate for even moderately precise prediction of subsidence events over previously mined-out areas; the accumulation of adequate data might not repay the effort in terms of damage prevention. 4. Commonwealth-of-Pennsylvania regulations, have been very successful in limiting mine-subsidence damage over areas mined after 1966. 5. Undermining and consequent subsidence may have affected the ground-water regime more widely than heretofore believed. Except for the earth-disturbance inventory that resulted in the maps of susceptibility to landsliding and man-modified land, methods used in the studies .largely were conventional. The inventory and ensuing analysis combined aerial photographic interpretation with field work and incorporation of existing data. The. method worked very well for the purposes of defining distribution of landslides and areas having different susceptibilities to landsliding. However, if susceptibility to landsliding alone had been the goal, this could

Large depressions, thickened terraces, and gravitational deformation in the Ebro River valley (Zaragoza area, NE Spain): Evidence of glauberite and halite interstratal karstification

NASA Astrophysics Data System (ADS)

Guerrero, Jesús; Gutiérrez, Francisco; Galve, Jorge P.

2013-08-01

In the studied reach of the Ebro Valley, the terrace and pediment sediments deposited over glauberite- and halite-bearing evaporites show local thickenings (> 50 m) recording dissolution-induced synsedimentary subsidence. Recent data on the lithostratigraphy of the evaporite sequence allow relating the alluvium thickenings with either halite or glauberite dissolution. The alluvium-filled dissolution basin underlying the youngest terraces (T8-T11) is ascribed to halite karstification; the top of a halite unit approximately 75 m thick is situated 40-15 m below the valley bottom. The thickenings of terrace (T1-T7) and pediment sediments are attributed to interstratal glauberite karstification: (1) Coincidence between the elevation range of the terraces and that of the glauberite-rich unit. Glauberite beds reach 30 and 100 m in single-bed and cumulative thickness, respectively. (2) The exposed bedrock underlying thickened alluvium shows abundant subsidence features indicative of interstratal karstification. The most common structure corresponds to hectometer-scale sag basins with superimposed collapses in the central sector of each basin. The subsided bedrock is frequently transformed into dissolution-collapse breccias showing a complete textural gradation, from crackle packbreccias to chaotic floatbreccias and karstic residues. (3) Paleokarst exposures show evidence of karstification confined to specific beds made up of secondary gypsum after precursory glauberite, partly dissolved and partly replaced. Despite the magnitude of the subsidence recorded by the thickened alluvium and unlike nearby tributaries, the terraces show a continuous and parallel arrangement indicating that the fluvial system was able to counterbalance subsidence by aggradation. A number of kilometer-size flat-bottom depressions have been developed in the valley margin, typically next to and inset into thickened terrace and pediment deposits. The subsidence structures exposed in artificial excavations excavated in the bottom of some depressions and the correlation between the altitudinal distribution of these basins and that of the glauberite-rich unit reveal that subsidence related to interstratal glauberite karstification is the main process involved in their genesis. This research ascribes for the first time the thickenings and deformation of specific terrace levels and pediment levels and the development of large karstic depressions to interstratal karstification of exceptionally thick glauberite units.

Examples of deformation-dependent flow simulations of conjunctive use with MF-OWHM

USGS Publications Warehouse

Hanson, Randall T.; Traum, Jonathan A.; Boyce, Scott E.; Schmid, Wolfgang; Hughes, Joseph D.

2015-01-01

The dependency of surface- and groundwater flows and aquifer hydraulic properties on deformation induced by changes in aquifer head is not accounted for in the standard version of MODFLOW. A new USGS integrated hydrologic model, MODFLOW-OWHM, incorporates this dependency by linking subsidence and mesh deformation with changes in aquifer transmissivity and storage coefficient, and with flows that also depend on aquifer characteristics and land-surface geometry. This new deformation-dependent approach is being used for the further development of the integrated Central Valley hydrologic model (CVHM) in California. Preliminary results from this application and from hypothetical test cases of similar systems show that changes in canal flows, stream seepage, and evapotranspiration from groundwater (ETgw) are sensitive to deformation. Deformation feedback has been shown to also have an indirect effect on conjunctive surface- and groundwater use components with increased stream seepage and streamflows influencing surface-water deliveries and return flows. In the Central Valley model, land subsidence may significantly degrade the ability of the major canals to deliver surface water from the Delta to the San Joaquin and Tulare basins. Subsidence can also affect irrigation demand and ETgw, which, along with altered surface-water supplies, causes a feedback response resulting in changed estimates of groundwater pumping for irrigation. This modeling feature also may improve the impact assessment of dewatering-induced land subsidence/uplift (following irrigation pumping or coal-seam gas extraction) on surface receptors, inter-basin transfers, and surface infrastructure integrity.

Characterizations of pumping-induced land subsidence in coastal aquifers - model development and field-scale implementations

NASA Astrophysics Data System (ADS)

Ni, C.; Huang, Y.; Lu, C.

2012-12-01

The pumping-induced land subsidence events are typically founded in coastal aquifers in Taiwan especially in the areas of lower alluvial fans. Previous investigations have recognized the irreversible situation for an aquifer deformation even if the pumped water is significantly reduced or stopped. Long-term monitoring projects on land subsidence in Choshui alluvial fan in central Taiwan have improved the understanding of the deformations in the aquifer system. To characterization the detailed land subsidence mechanism, this study develops an inverse numerical model to estimate the deformation parameters such as the specific storage (Ss) and vertical hydraulic conductivity (Kv) for interbeds. Similar to the concept of Hydraulic tomography survey (HTS), the developed model employs the iterative cokriging estimator to improve the accuracy of estimating deformation parameters. A one-dimensional numerical example is employed to assess the accuracy of the developed inverse model. The developed model is then applied to field-scale data from compaction monitoring wells (CMW) installed in the lower Choshui River fan. Results of the synthetic example show that the developed inverse model can reproduce well the predefined geologic features of the synthetic aquifer. The model provides better estimations of Kv patterns and magnitudes. Slightly less detail of the Ss was obtained due to the insensitivity of transient stresses for specified sampling times. Without prior information from field measurements, the developed model associated with deformation measurements form CMW can estimate Kv and Ss fields with great spatial resolution.

UAVSAR and TerraSAR-X Based InSAR Detection of Localized Subsidence in the New Orleans Area

NASA Astrophysics Data System (ADS)

Blom, R. G.; An, K.; Jones, C. E.; Latini, D.

2014-12-01

Vulnerability of the US Gulf coast to inundation has received increased attention since hurricanes Katrina and Rita. Compounding effects of sea level rise, wetland loss, and regional and local subsidence makes flood protection a difficult challenge, and particularly for the New Orleans area. Key to flood protection is precise knowledge of elevations and elevation changes. Analysis of historical and continuing geodetic measurements show surprising complexity, including locations subsiding more rapidly than considered during planning of hurricane protection and coastal restoration projects. Combining traditional, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations can provide geographically dense constraints on surface deformation. The Gulf Coast environment is challenging for InSAR techniques, especially with systems not designed for interferometry. We use two InSAR capable systems, the L- band (24 cm wavelength) airborne JPL/NASA UAVSAR, and the DLR/EADS Astrium spaceborne TerraSAR X-band (3 cm wavelength), and compare results. First, we are applying pair-wise InSAR to the longer wavelength UAVSAR data to detect localized elevation changes potentially impacting flood protection infrastructure from 2009 - 2014. We focus on areas on and near flood protection infrastructure to identify changes indicative of subsidence, structural deformation, and/or seepage. The Spaceborne TerraSAR X-band SAR system has relatively frequent observations, and dense persistent scatterers in urban areas, enabling measurement of very small displacements. We compare L-band UAVSAR results with permanent scatterer (PS-InSAR) and Short Baseline Subsets (SBAS) interferometric analyses of a stack composed by 28 TerraSAR X-band images acquired over the same period. Thus we can evaluate results from the different radar frequencies and analyses techniques. Preliminary results indicate subsidence features potentially of a variety of causes, including ground water pumping to post recent construction ground compaction. Our overall goal is to enable incorporation of InSAR into the decision making process via identification and delineation of areas of persistent subsidence, and provide input to improve monitoring and planning in flood risk areas.

Analysis of stress-strain state of support ring of vertical steel tank RVS-20000

NASA Astrophysics Data System (ADS)

Chepur, P. V.; Tarasenko, A. A.; Gruchenkova, A. A.

2018-05-01

The refined finite element model of the joint of a fixed roof with a support ring for a large-size vertical steel tank RVS-20000 is executed. It considers the real geometry of metal shell plates - in accordance with the TP-704-1-60 design, geometric and physical nonlinearity, and features of the non-axisymmetric design loading scheme of the structure. Dependences of the SSS parameters of the support joint design on the size of the subsidence zone of the outer contour of the RVS-20000 bottom are obtained. It is established that at the value of subsidence zone coefficient n ≤ 1, a region of critical values occurs, exceeding which leads to the appearance of unacceptable plastic deformations of metal structures. The authors performed interpretation of the postprocessing of the finite element analysis, as a result of which the dependences of the parameters of the stress-strain state on the value of the zone of warping were obtained. The graphs of the dependence of the values of strains and stresses of the metal structure of the support ring on the size of the subsidence zone along the arc of the outer contour of the bottom are presented.

High-resolution seismic-reflection imaging 25 years of change in I-70 sinkhole, Russell County, Kansas

USGS Publications Warehouse

Miller, R.D.; Steeples, D.W.; Lambrecht, J.L.; Croxton, N.

2006-01-01

Time-lapse seismic reflection imaging improved our understanding of the consistent, gradual surface subsidence ongoing at two sinkholes in the Gorham Oilfield discovered beneath a stretch of Interstate Highway 70 through Russell and Ellis Counties in Kansas in 1966. With subsidence occurring at a rate of around 10 cm per year since discovery, monitoring has been beneficial to ensure public safety and optimize maintenance. A miniSOSIE reflection survey conducted in 1980 delineated the affected subsurface and successfully predicted development of a third sinkhole at this site. In 2004 and 2005 a high-resolution vibroseis survey was completed to ascertain current conditions of the subsurface, rate and pattern of growth since 1980, and potential for continued growth. With time and improved understanding of the salt dissolution affected subsurface in this area it appears that these features represent little risk to the public from catastrophic failure. However, from an operational perspective the Kansas Department of Transportation should expect continued subsidence, with future increases in surface area likely at a slightly reduced vertical rate. Seismic characteristics appear empirically consistent with gradual earth material compaction/settling. ?? 2005 Society of Exploration Geophysicists.

Assessing the effect of mine subsidence on dwarf shrub ericoid heath communities within a site of national importance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humphries, R.N.; Wessemann, H.; Benyon, P.R.

1998-12-31

Planning consent was applied for in 1997 to extract coal from the Stanley Main seam beneath Skipwith Common, North Yorkshire in the United Kingdom. The 293ha Common is of national importance for its dwarf shrub ericoid heath communities, and has statutory protection under UK law as a Site of Special Scientific Interest (SSSI). Current planning guidance requires the effects of the mining proposals to be rigorously examined. The distribution of the heath vegetation is largely determined by the surface topography and sub-surface clay features, these determine relative site subsidence on drainage, and hence soil wetness and heath vegetation. Up tomore » date topographical, soil and vegetation surveys were undertaken. This data was used in conjunction with the mining company`s subsidence predictions to model the effects of the mining of the previous and deeper Barnsley seam, as well as the proposed extraction of the Stanley Main seam. Overall, the model predicted there would be no adverse effect of subsidence from the mining of the Barnsley seam or cumulative effects following the extraction of the Stanley Main seam on the site features which determine relative wetness and heath distribution. The prediction for the Barnsley seam was tested using past and current vegetation and soil wetness records. On a broad scale, there was no field evidence that the previous mining has resulted in a reduction in the extent of ericiod heath communities within the SSSI. On a local scale, there was some evidence for a very small effect at the one location where a potential effect was predicted. As the principal physical changes to the SSSI are induced by the previous mining of the Barnsley seam, no further effects were predicted for extracting the Stanley Main seam. The modelling approach has proved to be valuable, both technically and as a means of explaining the potential effects of mining on a nationally important nature conservation site to various interested parties, including the regulatory bodies.« less

A methodology for studying tectonic subsidence variations: insights from the Fernie Formation of west-central Alberta

NASA Astrophysics Data System (ADS)

McCartney, Tannis Maureen

Tectonic subsidence curves for over 300 subsurface wells in west-central Alberta indicate that the Western Canada Foreland Basin was initiated at the same time the lower units of the Fernie Formation were being deposited. This evidence is further supported by sedimentological data and fits with the timing of the onset of deformation in the Cordillera and the initiation of the foreland basin in Montana. The volume of subsidence curves in this study required an innovative methodology. Subsidence calculations were performed using customized macros in a spreadsheet. The tectonic subsidence variations were displayed in a tectonic subsidence envelope, which showed the total variation in the subsidence curves, and three suites of maps: tectonic subsidence, tectonic subsidence residuals, and tectonic subsidence ratios. Collectively, the maps of the tectonic subsidence in the Fernie Formation show that there was a western influence on subsidence during deposition of the oldest members of the Fernie Formation.

Hydrogeologic controls on the groundwater interactions with an acidic lake in karst terrain, Lake Barco, Florida

USGS Publications Warehouse

Lee, T.M.

1996-01-01

Transient groundwater interactions and lake stage were simulated for Lake Barco, an acidic seepage lake in the mantled karst of north central Florida. Karst subsidence features affected groundwater flow patterns in the basin and groundwater fluxes to and from the lake. Subsidence features peripheral to the lake intercepted potential groundwater inflow and increased leakage from the shallow perimeter of the lake bed. Simulated groundwater fluxes were checked against net groundwater flow derived from a detailed lake hydrologic budget with short-term lake evaporation computed by the energy budget method. Discrepancies between modeled and budget-derived net groundwater flows indicated that the model underestimated groundwater inflow, possibly contributed to by transient water table mounding near the lake. Recharge from rainfall reduced lake leakage by 10 to 15 times more than it increased groundwater inflow. As a result of the karst setting, the contributing groundwater basin to the lake was 2.4 ha for simulated average rainfall conditions, compared to the topographically derived drainage basin area of 81 ha. Short groundwater inflow path lines and rapid travel times limit the contribution of acid-neutralizing solutes from the basin, making Lake Barco susceptible to increased acidification by acid rain.

Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico)

NASA Astrophysics Data System (ADS)

Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.

2013-12-01

This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

Mechanisms, Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation (M3EF3): A UNESCO-IGCP project in partnership with the UNESCO-IHP Working Group on Land Subsidence

NASA Astrophysics Data System (ADS)

Teatini, P.; Carreon-Freyre, D.; Galloway, D. L.; Ye, S.

2015-12-01

Land subsidence due to groundwater extraction was recently mentioned as one of the most urgent threats to sustainable development in the latest UNESCO IHP-VIII (2014-2020) strategic plan. Although advances have been made in understanding, monitoring, and predicting subsidence, the influence of differential vertical compaction, horizontal displacements, and hydrostratigraphic and structural features in groundwater systems on localized near-surface ground ruptures is still poorly understood. The nature of ground failure may range from fissuring, i.e., formation of an open crack, to faulting, i.e., differential offset of the opposite sides of the failure plane. Ground ruptures associated with differential subsidence have been reported from many alluvial basins in semiarid and arid regions, e.g. China, India, Iran, Mexico, Saudi Arabia, Spain, and the United States. These ground ruptures strongly impact urban, industrial, and agricultural infrastructures, and affect socio-economic and cultural development. Leveraging previous collaborations, this year the UNESCO Working Group on Land Subsidence began the scientific cooperative project M3EF3 in collaboration with the UNESCO International Geosciences Programme (IGCP n.641; www.igcp641.org) to improve understanding of the processes involved in ground rupturing associated with the exploitation of subsurface fluids, and to facilitate the transfer of knowledge regarding sustainable groundwater management practices in vulnerable aquifer systems. The project is developing effective tools to help manage geologic risks associated with these types of hazards, and formulating recommendations pertaining to the sustainable use of subsurface fluid resources for urban and agricultural development in susceptible areas. The partnership between the UNESCO IHP and IGCP is ensuring that multiple scientific competencies required to optimally investigate earth fissuring and faulting caused by groundwater withdrawals are being employed.

Scenario-based projections of future urban inundation within a coupled hydrodynamic model framework: A case study in Dongguan City, China

NASA Astrophysics Data System (ADS)

Wu, Xushu; Wang, Zhaoli; Guo, Shenglian; Liao, Weilin; Zeng, Zhaoyang; Chen, Xiaohong

2017-04-01

One major threat to cities at present is the increased inundation hazards owing to changes in climate and accelerated human activity. Future evolution of urban inundation is still an unsolved issue, given large uncertainties in future environmental conditions within urbanized areas. Developing model techniques and urban inundation projections are essential for inundation management. In this paper, we proposed a 2D hydrodynamic inundation model by coupling SWMM and LISFLOOD-FP models, and revealed how future urban inundation would evolve for different storms, sea level rise and subsidence scenarios based on the developed model. The Shiqiao Creek District (SCD) in Dongguan City was used as the case study. The model ability was validated against the June 13th, 2008 inundation event, which occurred in SCD, and proved capable of simulating dynamic urban inundation. Scenario analyses revealed a high degree of consistency in the inundation patterns among different storms, with larger magnitudes corresponding to greater return periods. Inundations across SCD generally vary as a function of storm intensity, but for lowlands or regions without drainage facilities inundations tend to aggravate over time. In riverfronts, inundations would exacerbate with sea level rise or subsidence; however, the inland inundations are seemingly insensitive to both factors. For the combined scenario of 100-yr storm, 0.5 m subsidence and 0.7 m sea level rise, the riverside inundations would occur much in advance, whilst catastrophic inundations sweep across SCD. Furthermore, the optimal low-impact development found for this case study includes 0.2 km2 of permeable pavements, 0.1 km2 of rain barrels and 0.7 km2 of green roofs.

The UNESCO-IHP Working Group on Land Subsidence: Four Decades of International Contributions to Hydrogeological Related Subsidence Research and Knowledge Exchange

NASA Astrophysics Data System (ADS)

Galloway, D. L.; Carreon-Freyre, D.; Teatini, P.; Ye, S.

2015-12-01

Subsidence is globally prevalent and because much of it is related to hydrological processes affected by human development of local land and water resources, "Land Subsidence" was included in the UNESCO programme of the International Hydrological Decade (IHD), 1965-1974 and an ad hoc working group on land subsidence was formed. In 1975 subsidence was retained under the framework of the UNESCO IHP (subproject 8.4: "Investigation of Land Subsidence due to Groundwater Exploitation"), and UNESCO IHP formerly codified the Working Group on Land Subsidence (WGLS). In 1984 the WGLS produced a comprehensive guidebook to serve scientists and engineers, confronting land subsidence problems, particularly in developing countries (http://unesdoc.unesco.org/$other/unesdoc/pdf/065167eo.pdf). During the IHD, UNESCO IHP convened the 1st International Symposium on Land Subsidence in 1969 in Tokyo, Japan. In collaboration with UNESCO IHP, IAHS, and other scientific organizations, the WGLS has convened eight more International Symposia on Land Subsidence in different countries in Asia, Europe and North America. The 9 published symposia proceedings constitute an important source of global subsidence research and case studies during the past 45 years, covering both anthropogenic and natural subsidence processes. Currently, the WGLS comprising 20 subsidence experts from 9 countries promotes and facilitates the international exchange of information regarding the design, implementation and evaluation of risk assessments and mitigation measures, the definition of water and land resource-management strategies that support sustainable development in areas vulnerable to subsidence (http://landsubsidence-unesco.org), and the assessment of related geological risks such as earth fissuring and fault activation (www.igcp641.org). The WGLS has become an important global leader in promoting subsidence awareness, scientific research and its application to subsidence monitoring, analysis and management.

Using high-resolution satellite radar to measure lava flow morphology, rheology, effusion rate and subsidence at El Reventador Volcano, Ecuador.

NASA Astrophysics Data System (ADS)

Biggs, J.; Arnold, D. W. D.; Mothes, P. A.; Anderson, K. R.; Albino, F.; Wadge, G.; Vallejo Vargas, S.; Ebmeier, S. K.

2017-12-01

There are relatively few studies of active lava flows of an andesitic rather than basaltic composition. The flow field at El Reventador volcano, Ecuador is a good example, but observations are hampered by persistent cloud cover. We use high resolution satellite radar from Radarsat-2 and TanDEM-X to map the dimensions of 43 lava flows extruded between 9 Feb 2012 and 24 Aug 2016. Flow height is measured using the width of radar shadow cast by steep sided features, or the difference in radar phase between two sensors separated in space. The cumulative volume of erupted material was 44.8M m3 dense rock equivalent with an average rate of 0.31 ± 0.02 m3s-1, similar to the long term average. The flows were mostly emplaced over durations shorter than the satellite repeat interval of 24 days and ranged in length from 0.3 to 1.7 km. We use the dimensions of the levees to estimate the flow yield strengths and compare measurements of diversions around barriers with observations from laboratory experiments. The rate of effusion, flow length and flow volume all decrease with time, and simple physics-based models can be equally well fit by a closed reservoir depressurising during the eruption with no magma recharge, or an open reservoir with a time-constant magma recharge rate of up to 0.35 ± 0.01 m3s-1. We propose that the conduit acts as magma capacitor and individual flows are volume-limited. Emplaced flows are subsiding at rates proportional to lava thickness that decay with time following a square-root relationship. Radar observations, such as those presented here, could be used to map and measure properties of evolving lava flow fields at other remote or difficult to monitor volcanoes. Physics-based models can be run into the future, but a sudden increase in flow length in 2017 seen by Sentinel illustrates that changes in magma supply can cause rapid changes in behavior, which remain challenging to forecast.

InSAR measurements and numerical models of deformation at Brady Hot Springs geothermal field (Nevada), 1995-2012

NASA Astrophysics Data System (ADS)

Ali, S. T.; Davatzes, N. C.; Mellors, R. J.; Foxall, W.; Drakos, P. S.; Zemach, E.; Kreemer, C.; Wang, H. F.; Feigl, K. L.

2013-12-01

We study deformation due to changes in fluid pressure caused by pumping during production, injection, and stimulation at the Brady Hot Springs geothermal field in the Basin and Range province in Nevada. To measure the deformation, we analyze Interferometric Synthetic Aperture Radar (InSAR) data acquired by the ERS-1, ERS-2, Envisat, and TerraSAR-X satellites between 1995 and 2013. The InSAR results indicate subsidence at the order of several centimeters per year over an elliptically shaped area roughly ~5 km long by ~2 km wide. Its long axis follows the NNE strike of the predominant normal fault system. The subsiding area is centered near a prominent bend in the fault system where the successful production wells are located. Within this broad bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. To explain the deformation signal, we use poroelastic models constrained by borehole measurements of pressure, temperature and mass flux, as well as geologic observations. We solve the coupled deformation-diffusion problem using the finite element method. To estimate parameters in the model, e.g., permeability, we use the General Inversion for Phase Technique -- GIPhT [Feigl and Thurber, 2009; Ali and Feigl, 2012] that utilizes the gradient of range change and avoids the need for unwrapping the observed wrapped phase. We then solve the non-linear inverse problem using a gradient-based inversion scheme. Our results suggest that a complex network of high permeability conduits associated with intersections between fault segments and bends in fault segments explains the smaller length-scale features observed in the interferograms. Such structurally controlled, high permeability conduits are consistent with relatively recent fault slip evidenced by scarps in late Pleistocene Lake Lahontan sediments and spatially associated surface hydrothermal features that predate production at Brady. In contrast, Desert Peak, a "blind" geothermal field, located less than 7 km away from Brady, shows little or no deformation in the InSAR data set, although the two fields are otherwise similar in spatial extent, structural setting, and geothermal production. Desert Peak exhibits neither hydrothermal features nor any evidence of surficial fault slip, however, suggesting that the "plumbing" associated with the fault system there is deeper at than at Brady.

Subsidence transition during the post-rift stage of the Dongpu Sag, Bohai Bay Basin, NE China: A new geodynamic model

NASA Astrophysics Data System (ADS)

Xu, Han; Wang, Xin-Wen; Yan, Dan-Ping; Qiu, Liang

2018-06-01

The Dongpu Sag, located in the Bohai Bay Basin, NE China, is a Cenozoic continental rift basin. The post-rift evolution of the Dongpu Sag is associated with the development of petroleum reservoirs and has implications for Neogene-Quaternary basin evolution along the eastern margin of Eurasia. To determine the nature and origin of post-rift subsidence in the Dongpu Sag, we apply backstripping, modified strain-rate inversion, and revised finite extension modelling techniques, using data from 14 real and synthetic wells that are intersected by three seismic lines. Our results reveal discrepancies by subsidence based on backstripping of well data (the observed subsidence) minus that predicted by modified strain-rate inversion and revised finite extension modelling (the predicted subsidence). During the Miocene, the observed subsidence was smaller than the predicted subsidence, leaving negative discrepancies referred to here as "insufficient subsidence" ranging from -343 to -96 m. In contrast, during the Pliocene-Quaternary the observed subsidence was greater than the predicted subsidence by +123 to +407 m, which left positive discrepancies referred to as "over-sufficient subsidence". Therefore, we infer a transition from insufficient to over-sufficient subsidence during the post-rift stage. Normal faulting that started at ca. 5.3 Ma is estimated to have produced only ∼20% of the over-sufficient subsidence. Therefore, the remaining over-sufficient subsidence, as well as the preceding insufficient subsidence and the transition between the two, were likely controlled by lithosphere processes. We propose a new tectonic model in which variations in the conditions (e.g. rate, direction, and angle) associated with subduction of the Pacific plate resulted in a change of heat flow decreasing from a linear to a curvilinear pattern, leading to a transition from insufficient to over-sufficient subsidence.

Application of an adaptive neuro-fuzzy inference system to ground subsidence hazard mapping

NASA Astrophysics Data System (ADS)

Park, Inhye; Choi, Jaewon; Jin Lee, Moung; Lee, Saro

2012-11-01

We constructed hazard maps of ground subsidence around abandoned underground coal mines (AUCMs) in Samcheok City, Korea, using an adaptive neuro-fuzzy inference system (ANFIS) and a geographical information system (GIS). To evaluate the factors related to ground subsidence, a spatial database was constructed from topographic, geologic, mine tunnel, land use, and ground subsidence maps. An attribute database was also constructed from field investigations and reports on existing ground subsidence areas at the study site. Five major factors causing ground subsidence were extracted: (1) depth of drift; (2) distance from drift; (3) slope gradient; (4) geology; and (5) land use. The adaptive ANFIS model with different types of membership functions (MFs) was then applied for ground subsidence hazard mapping in the study area. Two ground subsidence hazard maps were prepared using the different MFs. Finally, the resulting ground subsidence hazard maps were validated using the ground subsidence test data which were not used for training the ANFIS. The validation results showed 95.12% accuracy using the generalized bell-shaped MF model and 94.94% accuracy using the Sigmoidal2 MF model. These accuracy results show that an ANFIS can be an effective tool in ground subsidence hazard mapping. Analysis of ground subsidence with the ANFIS model suggests that quantitative analysis of ground subsidence near AUCMs is possible.

Towards a Global Land Subsidence Map

NASA Astrophysics Data System (ADS)

Erkens, G.; Kooi, H.; Sutanudjaja, E.

2017-12-01

Land subsidence is a global problem, but a global land subsidence map is not available yet. Such map is crucial to raise global awareness of land subsidence, as land subsidence causes extensive damage (probably in the order of billions of dollars annually). Insights in the rates of subsidence are particularly relevant for low lying deltas and coastal zones, for which any further loss in elevation is unwanted. With the global land subsidence map relative sea level rise predictions may be improved, contributing to global flood risk calculations. In this contribution, we discuss the approach and progress we have made so far in making a global land subsidence map. The first results will be presented and discussed, and we give an outlook on the work needed to derive a global land subsidence map.

Lower crustal flow and the role of shear in basin subsidence: An example from the Dead Sea basin

USGS Publications Warehouse

Al-Zoubi, A.; ten Brink, Uri S.

2002-01-01

We interpret large-scale subsidence (5–6 km depth) with little attendant brittle deformation in the southern Dead Sea basin, a large pull-apart basin along the Dead Sea transform plate boundary, to indicate lower crustal thinning due to lower crustal flow. Along-axis flow within the lower crust could be induced by the reduction of overburden pressure in the central Dead Sea basin, where brittle extensional deformation is observed. Using a channel flow approximation, we estimate that lower crustal flow would occur within the time frame of basin subsidence if the viscosity is ≤7×1019–1×1021 Pa s, a value compatible with the normal heat flow in the region. Lower crustal viscosity due to the strain rate associated with basin extension is estimated to be similar to or smaller than the viscosity required for a channel flow. However, the viscosity under the basin may be reduced to 5×1017–5×1019 Pa s by the enhanced strain rate due to lateral shear along the transform plate boundary. Thus, lower crustal flow facilitated by shear may be a viable mechanism to enlarge basins and modify other topographic features even in the absence of underlying thermal anomalies.

Effect of Radiative Cooling on Cloud-SST Relationship within the Tropical Pacific Region

NASA Technical Reports Server (NTRS)

Sui, Chung-Hsiung; Ho, Chang-Hoi; Chou, Ming-Dah; Lau, Ka-Ming; Li, Xiao-Fan; Einaudi, Franco (Technical Monitor)

2000-01-01

A recent analysis found a negative correlation between the area-mean cloud amount and the corresponding mean Sea Surface Temperature (SST) within the cloudy areas. The SST-cloud relation becomes more evident when the SST contrast between warm pool and surrounding cold pool (DSST) in the tropical Pacific is stronger than normal. The above feature is related to the finding that the strength of subsidence over the cold pool is limited by radiative cooling because of its small variability. As a result, the area of radiatively-driven subsidence must expand in response to enhanced low-boundary forcing due to SST warming or enhanced basin-scale DSST. This leads to more cloud free regions and less cloudy regions. The increased ratio of cloud-free areas to cloudy areas leads to more high SST areas (>29.50C) due to enhanced solar radiation.

Possible terrestrial analogs of Valhalla and other ripple-ring basins

NASA Technical Reports Server (NTRS)

Wood, C. A.

1981-01-01

The most remarkable feature on Callisto is Valhalla, a 3000 km wide structure comprised of dozens of concentric ridges and scarps surrounding a central smooth zone. Conventionally, Valhalla is interpreted as a multi-ring impact basin (similar to those on the terrestrial planets) whose morphology has been strongly effected by a thin and weak icy lithosphere in which it formed. Alternatively, Valhalla may have been formed by some non-impact related processes. In particular, ice cauldrons formed in Iceland by subsidence of glacier ice into voids created by geothermal melting are grossly similar to Valhalla in that both formed in ice and have multiple rings. Theoretical support for a similar subsidence mode of origin for Valhalla is provided by models of the thermal evolution of ice-silicate planets that result in diapiric sinking of lithospheric material into a water mantle (e.g., Paramentier and Head, 1979).

Subsidence of the South Polar Terrain and global tectonic of Enceladus

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2016-04-01

Introduction: Enceladus is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of ˜200 kg is ejected into space from the South Polar Terrain (SPT) - [1]. The loss of matter from the body's interior should lead to global compression of the crust (like on Mercury). Typical effects of compression are: thrust faults, folding and subduction. However, such forms are not dominant on Enceladus. We propose here special dynamical process that could explain this paradox. Our hypothesis states that the mass loss from SPT is the main driving mechanism of the following tectonic processes: subsidence of SPT, flow in the mantle and motion of adjacent tectonic plates. The hypothesis is presented in [2] and [3]. We suggest that the loss of the volatiles results in a void, an instability, and motion of solid matter to fill the void. The motion includes: Subsidence of the 'lithosphere' of SPT. Flow of the matter in the mantle. Motion of plates adjacent to SPT towards the active region. Methods and results: The numerical model of the subsidence process is developed. It is based on the model of thermal convection in the mantle. Special boundary conditions are applied, that could simulate subsidence of SPT. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is ˜0.05 mmṡyr-1. However, numerical calculations indicate that all three types of motion are usually important. The role of a given motion depends on the viscosity distribution. Generally, for most of the models the subsidence is ˜0.02 mmṡyr-1, but mantle flow and plates' motion also play a role in filling the void. The preliminary results of the numerical model indicate also that the velocity of adjacent plates could be ˜0.02 mmṡyr-1 for the Newtonian rheology. Note that in our model the reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. The SPT is compressed, so "tiger stripes" could exist for long time. Only after significant subsidence (below 1200 m) the regime of stresses changes to compressional. We suppose that it means the end of activity in a given region. Acknowledgments This work was partially supported by the National Science Centre (grant 2011/01/B/ST10/06653). Computer resources of Interdisciplinary Centre for Mathematical and Computational Modeling of University of Warsaw were also used in the research References [1] Spencer, J. R., et al. (2009) Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer Science, p. 683. [2] Czechowski L. (2015) Mass loss as a driving mechanism of tectonics of Enceladus 46th Lunar and Planetary Science Conference 2030.pdf. [3] Czechowski, L., (2014) Some remarks on the early evolution of Enceladus. Planet. Sp. Sc. 104, 185-199.

Accommodation space, relative sea level, and the archiving of paleo-earthquakes along subduction zones

USGS Publications Warehouse

Kelsey, Harvey M.; Engelhart, Simon E.; Pilarczyk, Jessica E.; Horton, Benjamin P.; Rubin, Charles; Daryono, Mudrik; Ismail, Nazli; Hawkes, Andrea D.; Bernhardt, Christopher E.; Cahill, Niamh

2015-01-01

The spatial variability of Holocene relative sea-level (RSL) change influences the capacities of coastal environments to accommodate a sedimentary record of paleoenvironmental change. In this study we couch a specific investigation in more general terms in order to demonstrate the applicability of the relative sea-level history approach to paleoseismic investigations. Using subsidence stratigraphy, we trace the different modes of coastal sedimentation over the course of time in the eastern Indian Ocean where RSL change evolved from rapidly rising to static from 8000 yr ago to present. Initially, the coastal sites from the Aceh, Sumatra, coastal plain, which are subject to repeated great earthquakes and tsunamis, built up a sedimentary sequence in response to a RSL rise of 1.4 mm/yr. The sequence found at 2 sites 8 km apart contained 3 soils of a mangrove origin (Rhizophora,Bruguiera/Ceriops, Avicennia pollen, and/or intertidal foraminifera) buried by sudden submergence related to coseismic subsidence and 6 tsunami sands that contain pristine subtidal and planktic foraminifera. After 3800 cal yr B.P. (years before A.D. 1950), sea level stabilized and remained such to the present. The stable relative sea level reduced accommodation space in the late Holocene, suggesting that the continued aggradation of the coastal plain was a consequence of periodic coastal inundation by tsunamis.

Land subsidence in Yunlin, Taiwan, due to Agricultural and Domestic Water Use

NASA Astrophysics Data System (ADS)

Hsu, K.; Lin, P.; Lin, Z.

2013-12-01

Subsidence in a layered aquifer is caused by groundwater excess extraction and results in complicated problems in Taiwan. Commonly, responsibility to subsidence for agricultural and domestic water users is difficulty to identify due to the lack of quantitative evidences. An integrated model was proposed to analyze subsidence problem. The flow field utilizes analytical solution for pumping in a layered system from Neuman and Witherspoon (1969) to calculate the head drawdown variation. The subsidence estimation applies Terzaghi (1943) one-dimensional consolidation theory to calculate the deformation in each layer. The proposed model was applied to estimate land subsidence and drawdown variation at the Yuanchang Township of Yunlin County in Taiwan. Groundwater data for dry-season periods were used for calibration and validation. Seasonal effect in groundwater variation was first filtered out. Dry-season pumping effect on land subsidence was analyzed. The results show that multi-layer pumping contributes more in subsidence than single-layer pumping on the response of drawdown and land subsidence in aquifer 2 with a contribution of 97% total change at Yuanchang station. Pumping in aquifer 2 contributes more significant than pumping in aquifer 3 to cause change in drawdown and land subsidence in aquifer 2 with a contribution of 70% total change at Yuanchang station. Larger area of subsidence in Yuanchang Township was attributed pumping at aquifer 2 while pumping at aquifer 3 results in significant subsidence near the well field. The single-layer user contributes most area of subsidence but the multi-layer user generates more serious subsidence.

Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing.

PubMed

Guo, Jiming; Zhou, Lv; Yao, Chaolong; Hu, Jiyuan

2016-09-14

The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined.

Surface Subsidence Analysis by Multi-Temporal InSAR and GRACE: A Case Study in Beijing

PubMed Central

Guo, Jiming; Zhou, Lv; Yao, Chaolong; Hu, Jiyuan

2016-01-01

The aim of this study was to investigate the relationship between surface subsidence and groundwater changes. To investigate this relationship, we first analyzed surface subsidence. This paper presents the results of a case study of surface subsidence in Beijing from 1 August 2007 to 29 September 2010. The Multi-temporal Interferometric Synthetic Aperture Radar (multi-temporal InSAR) technique, which can simultaneously detect point-like stable reflectors (PSs) and distributed scatterers (DSs), was used to retrieve the subsidence magnitude and distribution in Beijing using 18 ENVISAT ASAR images. The multi-temporal InSAR-derived subsidence was verified by leveling at an accuracy better than 5 mm/year. Based on the verified multi-temporal InSAR results, a prominent uneven subsidence was identified in Beijing. Specifically, most of the subsidence velocities in the downtown area were within 10 mm/year, and the largest subsidence was detected in Tongzhou, with velocities exceeding 140 mm/year. Furthermore, Gravity Recovery and Climate Experiment (GRACE) data were used to derive the groundwater change series and trend. By comparison with the multi-temporal InSAR-derived subsidence results, the long-term decreasing trend between groundwater changes and surface subsidence showed a relatively high consistency, and a significant impact of groundwater changes on the surface subsidence was identified. Additionally, the spatial distribution of the subsidence funnel was partially consistent with that of groundwater depression, i.e., the former possessed a wider range than the latter. Finally, the relationship between surface subsidence and groundwater changes was determined. PMID:27649183

A record of Appalachian denudation in postrift Mesozoic and Cenozoic sedimentary deposits of the U.S. Middle Atlantic continental margin

USGS Publications Warehouse

Poag, C.W.; Sevon, W.D.

1989-01-01

The complex interplay between source-terrain uplift, basin subsidence, paleoclimatic shifts, and sea-level change, left an extensive sedimentary record in the contiguous offshore basins of the U.S. middle Atlantic margin (Salisbury Embayment, Baltimore Canyon Trough, and Hatteras Basin). Isopach maps of 23 postrift (Lower Jurassic to Quaternary) a allostratigraphic units, coupled with a revised stratigraphic framework, reveal that tectonism, by regulating sediment supply (accumulation rate), dominated the interplay of forcing mechanisms. Tectonic pulses are evidenced by abruptly accelerated sediment accumulation, marked latitudinal shifts in the location of depocenters, and regional changes in lithofacies. Relatively rapid tectonic subsidence during the Early and Middle Jurassic history of the basins may have enhanced sediment accumulation rates. Beginning in the Late Jurassic, however, subsidence rates decreased significantly, though occasional short pulses of subsidence may have effected relative sea-level rises. Sea-level change heavily influenced the distribution and redistribution of sediments one they reached the basins, and paleoclimate regulated the relative abundance of carbonates and evaporites in the basins. We conclude that source terrains of the central Appalachian Highlands were tectonically uplifted, intensely weathered, and rapidly eroded three times since the Late Triassic: (1) Early to Middle Jurassic (Aalenian to Callovian); (2) mid-Early Cretaceous (Barremian); and (3) Late Cenozoic (Middle Miocene). Intervals of tectonic quiescence following these three tectonic pulses provided conditions suitable for the formation of regional erosion surfaces, geomorphic features commonly reported to characterize the central Appalachian Highlands. This series of three, irregularly spaced, tectonic/quiescent cycles does not, however, match the traditional four-cycle concept of post-Triassic Appalachian "peneplanation". ?? 1989.

Distributed deformation structures in shallow water carbonates subsiding through a simple stress field (Jandaira Formation, NE Brazil)

NASA Astrophysics Data System (ADS)

Bertotti, Giovanni; Bisdom, Kevin; Bezerra, Hilario; Reijmer, John; Cazarin, Carol

2016-04-01

Despite the scarcity of major deformation structures such as folds and faults, the flat-lying, post-rift shallow water carbonates of the Jandaira Formation (Potiguar Basin, NE Brazil) display well-organized fracture systems distributed of tens of km2. Structures observed in the outcropping carbonates are sub-vertical, generally N-S trending mode I and hybrid veins and barren fractures, sub-vertical roughly E-W trending stylolites and sub-horizontal stylolites. These features developed during subsidence in a simple and constant stress field characterized by, beside gravity, a significant horizontal stress probably of tectonic origin. The corresponding depth curves have different origin and slopes and, therefore, cross each other resulting in position of the principal stresses which change with depth. As a result, the type and amount of fractures affecting subsiding rocks change despite the fact that the far-field stresses remain constant. Following early diagenesis and porosity elimination in the first 100-200m depth, Jandaira carbonates experienced wholesale fracturing at depths of 400-800m resulting in a network of NNW-NE trending fractures partly organized in conjugate sets with a low interfault angle and a sub-vertical intersection, and sub-vertical stylolites roughly perpendicular to the fractures. Intense fluid circulation was activated as a consequence through the carbonates. With increasing subsidence, sub-horizontal stylolites formed providing calcite which precipitated in the open fractures transforming them in veins. The Jandaira formation lost thereby the permeability it had reached during the previous stage. Because of the lack of major deformation, the outcrops of the Jandaira Formation is an excellent analog for carbonate reservoirs in the Middle East, South Atlantic and elsewhere.

Ert Applied to the Characterization of Subsidence in Mexico City: Ancient Structures Affecting Urban Utilities

NASA Astrophysics Data System (ADS)

Arango, C.; Chavez, R. E.; Cifuentes-Nava, G.; Hernández-Quintero, E.

2013-05-01

The problem of subsidence in Mexico City is basically due to the rapid extraction of groundwater for water supply in addition to the geological conditions. The most typical manifestations of the phenomena are presented as cracks and fractures due to compaction of ancient lake clayish sediments. This phenomenon has caused major affectations to city infrastructure because of the differential subsidence. Fractured buildings, sinkholes, among others manifestations, are potentially sources of collapses, which exposes the population to a serious risk. A small portion of Iztacalco County is being affected by this problem, specifically, in a crossroad formed by two important avenues: La Viga and Plutarco Elias Calles, where the area apparently increases its topographical level. The Electrical Resistivity Tomography technique was selected in order to obtain a resistivity image of the subsoil, which allows identify the main features associated to the terrain uprising. Three (ERT) profiles 200 m, were deployed on the mentioned crossroad in order to characterize the subsurface structures affecting the topographical level of the avenues. A big resistivity anomaly (~ 1000 ohm-m) could be observed towards the central part of the crossroad, coinciding with the major lifting level on surface. This feature appears at 15 m deep in all the profiles and depicts an approximate extension of 100 m in the E-W direction and 60 m in N-S axis. On the other hand, the surrounding material seems to correspond to a higher-saturated environment (lacustrine sediments <10 ohm-m). Shallow anomalies were also detected related to urban artifacts (pipes, sewers, etcetera). The apparently terrain uprising can be associated to a differential subsidence. However, the mentioned avenues were ancient water channels since pre-Hispanic times, where the caudal was enough to allow small steam boating at late nineteenth century. These waterways served as main routes for the exchange of goods during colonial times until the early twentieth century, and just at the junction of the channels, there was a custom gate, where the merchandise used to be registered before its arrival to the downtown market. We suspect that these high resistivity structures could be remains of those buildings that were not removed when the authorities decided to drain the channels in 1921.

Subsidence in tropical peatlands: Estimating CO2 fluxes from peatlands in Southeast Asia

NASA Astrophysics Data System (ADS)

Hoyt, A.; Harvey, C. F.; Seppalainen, S. S.; Chaussard, E.

2017-12-01

Tropical peatlands of Southeast Asia are an important global carbon stock. However, they are being rapidly deforested and drained. Peatland drainage facilitates peat decomposition, releases sequestered peat carbon to the atmosphere as CO2, and leads to subsidence of the peat surface. As a result, subsidence measurements can be used to monitor peatland carbon loss over time. Until now, subsidence measurements have been primarily limited to ground-based point measurements using subsidence poles. Here we demonstrate a powerful method to measure peatland subsidence rates across much larger areas than ever before. Using remotely sensed InSAR data, we map subsidence rates across thousands of square kilometers in Southeast Asia and validate our results against ground-based subsidence measurements. The method allows us to monitor subsidence in remote locations, providing unprecedented spatial information, and the first comprehensive survey of land uses such as degraded peatlands, burnt and open areas, shrub lands, and smallholder farmlands. Strong spatial patterns emerged, with the highest subsidence rates occurring at the centers of peat domes, where the peat is thickest and drainage depths are likely to be largest. Peatland subsidence rates were also strongly dependent on current and historical land use, with typical subsidence rates ranging from 2-4 cm/yr. Finally, we scaled up our results to calculate total annual emissions from peat decomposition in degraded peatlands.

Avian utilization of subsidence wetlands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nawrot, J.R.; Conley, P.S.; Smout, C.L.

1995-09-01

Diverse and productive wetlands have resulted from coal mining in the midwest. The trend from surface to underground mining has increased the potential for subsidence. Planned subsidence of longwall mining areas provides increased opportunities for wetland habitat establishment. Planned subsidence over a 180 meter (590 foot) deep longwall mine in southern Illinois during 1984 to 1986 produced three subsidence wetlands totaling 15 hectares (38 acres). The resulting palustrine emergent wetlands enhanced habitat diversity within the surrounding palustrine forested unsubsided area. Habitat assessments and evaluations of avian utilization of the subsidence wetlands were conducted during February 1990 through October 1991. Avianmore » utilization was greatest within the subsided wetlands. Fifty-three bird species representing seven foraging guilds utilized the subsidence wetlands. Wading/fishing, dabbling waterfowl, and insectivorous avian guilds dominated the subsidence wetlands. The subsidence wetlands represented ideal habitat for wood ducks and great blue herons which utilized snags adjacent to and within the wetlands for nesting (19 great blue heron nests produced 25 young). Dense cover and a rich supply of macroinvertebrates provide excellent brood habitat for wood ducks, while herpetofauna and ichthyofauna provided abundant forage in shallow water zones for great blue herons and other wetland wading birds. The diversity of game and non-game avifauna utilizing the subsidence areas demonstrated the unique value of these wetlands. Preplanned subsidence wetlands can help mitigate loss of wetland habitats in the midwest.« less

Using SPSS syntax: a beginner's guide Jacqueline Collier Using SPSS syntax: a beginner's guide Sage Pages: 216 £24.99 9781412922180 1412922186 [Formula: see text].

PubMed

2011-01-21

As someone who is comfortable with analysing data in SAS using coding language, it is perplexing that I run from the use of syntax in SPSS. But, my apprehension has subsided with the Collier's guide. Syntax command can automate processes, increase reproducibility and give the user broader access to features otherwise unavailable in SPSS.

Age and significance of earthquake-induced liquefaction near Vancouver, British Columbia, Canada

USGS Publications Warehouse

Clague, J.J.; Naesgaard, E.; Nelson, A.R.

1997-01-01

In late 1994, sand dykes, large sand blows, and deformed strata were exposed in the walls of an excavation at Annacis Island on the Fraser River delta near Vancouver, British Columbia. The features record liquefaction during a large earthquake about 1700 years ago; this was perhaps the largest earthquake to affect the Vancouver area in the last 3500 years. Similar, less well-dated features have been reported from several other sites on the Fraser delta and may be products of the same earthquake. Three radiocarbon ages that closely delimit the time of liquefaction on Annacis Island are similar to the most precise radiocarbon ages on coseismically subsided marsh soils at estuaries in southern Washington and Oregon. Both the liquefaction and the subsidence may have been produced by a single great plate-boundary earthquake at the Cascadia subduction zone. Alternatively, liquefaction at Annacis Island may have been caused by a large crustal or subcrustal earthquake of about the same age as a plate-boundary earthquake farther west. The data from Annacis Island and other sites on the Fraser delta suggest that earthquakes capable of producing extensive liquefaction in this area are rare events. Further, liquefaction analysis using historical seismicity suggests that current assessment procedures may overestimate liquefaction risk.

Hydrogeology and simulation of ground-water flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Robinson, James L.

2004-01-01

As a part of the Texas Water Development Board Ground- Water Availability Modeling program, the U.S. Geological Survey developed and tested a numerical finite-difference (MODFLOW) model to simulate ground-water flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system in Texas from predevelopment (before 1891) through 2000. The model is intended to be a tool that water-resource managers can use to address future ground-water-availability issues.From land surface downward, the Chicot aquifer, the Evangeline aquifer, the Burkeville confining unit, the Jasper aquifer, and the Catahoula confining unit are the hydrogeologic units of the Gulf Coast aquifer system. Withdrawals of large quantities of ground water have resulted in potentiometric surface (head) declines in the Chicot, Evangeline, and Jasper aquifers and land-surface subsidence (primarily in the Houston area) from depressurization and compaction of clay layers interbedded in the aquifer sediments. In a generalized conceptual model of the aquifer system, water enters the ground-waterflow system in topographically high outcrops of the hydrogeologic units in the northwestern part of the approximately 25,000-square-mile model area. Water that does not discharge to streams flows to intermediate and deep zones of the system southeastward of the outcrop areas where it is discharged by wells and by upward leakage in topographically low areas near the coast. The uppermost parts of the aquifer system, which include outcrop areas, are under water-table conditions. As depth increases in the aquifer system and as interbedded sand and clay accumulate, water-table conditions evolve into confined conditions.The model comprises four layers, one for each of the hydrogeologic units of the aquifer system except the Catahoula confining unit, the assumed no-flow base of the system. Each layer consists of 137 rows and 245 columns of uniformly spaced grid blocks, each block representing 1 square mile. Lateral no-flow boundaries were located on the basis of outcrop extent (northwestern), major streams (southwestern, northeastern), and downdip limit of freshwater (southeastern). The MODFLOW general-head boundary package was used to simulate recharge and discharge in the outcrops of the hydrogeologic units. Simulation of land-surface subsidence (actually, compaction of clays) and release of water from storage in the clays of the Chicot and Evangeline aquifers was accomplished using the Interbed-Storage Package designed for use with the MODFLOW model. The model was calibrated by trial-anderror adjustment of selected model input data in a series of transient simulations until the model output (potentiometric surfaces, land-surface subsidence, and selected water-budget components) reasonably reproduced field measured (or estimated) aquifer responses.Model calibration comprised four elements: The first was qualitative comparison of simulated and measured heads in the aquifers for 1977 and 2000; and quantitative comparison by computation and areal distribution of the root-mean-square error between simulated and measured heads. The second calibration element was comparison of simulated and measured hydrographs from wells in the aquifers in a number of counties throughout the modeled area. The third calibration element was comparison of simulated water-budget componentsprimarily recharge and dischargeto estimates of physically reasonable ranges of actual water-budget components. The fourth calibration element was comparison of simulated land-surface subsidence from predevelopment to 2000 to measured land surface subsidence from 1906 through 1995.

[Primary investigation of formation and genetic mechanism of land subsidence based on PS-InSAR technology in Beijing].

PubMed

Lei, Kun-chao; Chen, Bei-bei; Jia, San-man; Wang, Shu-fang; Luo, Yong

2014-08-01

The present paper adopts permanent scatterer interferometric synthetic aperture radar(PS-InSAR) technique to obtain land subsidence information in Beijing plain area. Then, combined with the time series of meteorological data, groundwater dynamic monitoring data, interferometric data and geological structure data, the formation and evolution mechanism of land subsidence were revealed. The results show that (1) Beijing regional land subsidence characteristics are obvious, more land subsidence funnel areas are interconnected, the settlement is influenced by rainfall recharge and exhibits seasonal fluctuation characteristics; (2) The land subsidence center and groundwater drawdown funnel centre are not fully consistent, unconfined aquifer and shallow confined aquifer are the major contribution factors and have greater impact on the land subsidence; (3) Land subsidence mainly occurred in the clay layer with a thickness of 50-70 m; (4) Land subsidence caused by tectonic controls is significant and the deformation gradient is great on both sides of the fault.

SURFACE FISSURE FORMATION ABOVE UNDERGROUND COALSEAM FIRES: DIMENSIONLESS RELATIONSHIPS BETWEEN SURFACE FISSURES AND SUBSURFACE SUBSIDENCE

NASA Astrophysics Data System (ADS)

Ide, T. S.; Pollard, D. D.; Orr, F. M.

2009-12-01

Coalbed fires are uncontrolled subsurface fires that occur around the world. These fires are believed to be significant contributors to annual CO2 emissions. Although many of these fires have been burning for decades, researchers have only recently begun to investigate physical mechanisms that control fire behavior. One aspect that is poorly characterized is the relationship between subsurface combustion and surface fissures. At the surface above many fires, long, wide fissures are observed. At a coalbed fire near Durango, Colorado, these fissures form systematic orthogonal patterns that align with regional joints in the Upper Cretaceous Fruitland Formation. Understanding the mechanisms that form and widen these fissures is important, as the fissures are believed to play vital roles in sustaining the combustion in the subsurface by acting as chimneys for the escaping gases and conduits for incoming oxygen. In some of the coalbed fire simulation models available today, these fissures are treated as fixed boundary conditions, but we argue, using field observations and simulation results, that there exists a relationship between the location and magnitude of subsidence caused by the fire and the opening of fissures. Four distinct types of fissures are observed over the coalbed fire near Durango, CO. These fissures are termed ‘molehill’, ‘plateau’, ‘gaping’, and ‘narrow’ based on their surface appearances. Molehill fissures are marked by surface depressions on either side, causing the strata around the opening to form an apex towards the center of the fissure. Plateau fissures show a steep vertical offset on only one side with minimal horizontal displacement. Gaping fissures and narrow fissures are predominantly opening with little evidence for vertical displacements. Gaping fissures are defined as fissures with wide apertures (0.3 ~ 1.5m), while narrow fissures have apertures on the order of centimeters. A boundary element method code was used to show that relationships exist between the surface displacement magnitudes and directions, and the subsurface subsidence due to coal combustion. Subsidence variables include the length, magnitude, depth and location of subsidence, as well as the weight of the overburden. Each of the four types of surface features was related to these subsurface subsidence variables using a set of dimensionless curves. The simulation results were validated with field measurements from a nearby outcrop and borehole drilling. The possibility of using InSAR data to further constrain these model results is being investigated. The simulated dimensionless curves establish a useful rules of thumb to aid the interpretation and mitigation of coal fires, since these curves can be used to relate a surface fissures aperture, an easily measurable parameter, to variables such as the magnitude of subsurface subsidence that are harder to observe

Ensemble of ground subsidence hazard maps using fuzzy logic

NASA Astrophysics Data System (ADS)

Park, Inhye; Lee, Jiyeong; Saro, Lee

2014-06-01

Hazard maps of ground subsidence around abandoned underground coal mines (AUCMs) in Samcheok, Korea, were constructed using fuzzy ensemble techniques and a geographical information system (GIS). To evaluate the factors related to ground subsidence, a spatial database was constructed from topographic, geologic, mine tunnel, land use, groundwater, and ground subsidence maps. Spatial data, topography, geology, and various ground-engineering data for the subsidence area were collected and compiled in a database for mapping ground-subsidence hazard (GSH). The subsidence area was randomly split 70/30 for training and validation of the models. The relationships between the detected ground-subsidence area and the factors were identified and quantified by frequency ratio (FR), logistic regression (LR) and artificial neural network (ANN) models. The relationships were used as factor ratings in the overlay analysis to create ground-subsidence hazard indexes and maps. The three GSH maps were then used as new input factors and integrated using fuzzy-ensemble methods to make better hazard maps. All of the hazard maps were validated by comparison with known subsidence areas that were not used directly in the analysis. As the result, the ensemble model was found to be more effective in terms of prediction accuracy than the individual model.

Flexural subsidence and basement tectonics of the Cretaceous Western Interior basin, United States

NASA Astrophysics Data System (ADS)

Pang, Ming; Nummedal, Dag

1995-02-01

The flexural subsidence history recorded in Cenomanian to early Campanian (97 to 80 Ma) strata in the Cretaceous U.S. Western Interior basin was studied with two-dimensional flexural backstripping techniques. Results indicate that the flexural subsidence resulting from thrust loading was superimposed on epeirogenic subsidence in the foreland basin. The flexural component exhibits significant spatial and temporal variations along both the strike and dip relative to the Sevier thrust belt. The greatest cumulative subsidence occurred in southwestern Wyoming and northern Utah. Concurrent subsidence in northwestern Montana and southern Utah was insignificant. Temporal trends in subsidence also show a distinct regional pattern. From the Cenomanian to late Turonian (97 to 90 Ma), subsidence rates were high in Utah and much lower in Wyoming and Montana. In contrast, during the Coniacian and Santonian (90 to 85 Ma) subsidence accelerated rapidly in Wyoming, increased slightly in Montana, and decreased in Utah. We suggest that these spatially and temporally varying subsidence patterns reflect the interplay of several geodynamic factors, including: (1) temporal and spatial variation in emplacement of the thrust loads, (2) segmentation of the basement into adjacent blocks with different rheological properties, (3) reactivation of basement fault trends, and (4) regional dynamic topographic effects.

Prediction of optimal safe ground water yield and land subsidence in the Los Banos-Kettleman City area, California, using a calibrated numerical simulation model

NASA Astrophysics Data System (ADS)

Larson, K. J.; Başaǧaoǧlu, H.; Mariño, M. A.

2001-02-01

Land subsidence caused by the excessive use of ground water resources has traditionally caused serious and costly damage to the Los Banos-Kettleman City area of California's San Joaquin Valley. Although the arrival of surface water from the Central Valley Project has reduced subsidence in recent decades, the growing instability of surface water supplies has refocused attention on the future of land subsidence in the region. This paper uses integrated numerical ground water and land subsidence models to simulate land subsidence caused by ground water overdraft. The simulation model is calibrated using observed data from 1972 to 1998, and the responsiveness of the model to variations in subsidence parameters are analyzed through a sensitivity analysis. A probable future drought scenario is used to evaluate the effect on land subsidence of three management alternatives over the next thirty years. The model reveals that maintaining present practices virtually eliminates unrecoverable land subsidence, but may not be a sustainable alternative because of a growing urban population to the south and concern over the ecological implications of water exportation from the north. The two other proposed management alternatives reduce the dependency on surface water by increasing ground water withdrawal. Land subsidence is confined to tolerable levels in the more moderate of these proposals, while the more aggressive produces significant long-term subsidence. Finally, an optimization model is formulated to determine maximum ground water withdrawal from nine pumping sub-basins without causing irrecoverable subsidence during the forecast period. The optimization model reveals that withdrawal can be increased in certain areas on the eastern side of the study area without causing significant inelastic subsidence.

Combining terrestrial, air-, and space-borne remote sensing for permafrost thaw subsidence change detection in Arctic Alaska

NASA Astrophysics Data System (ADS)

Günther, F.; Grosse, G.; Ulrich, M.; Nitze, I.; Sachs, T.; Jones, B. M.

2017-12-01

The unique feature of permafrost in the Arctic is the presence of a large amount of ice below the earth surface. Thermal degradation and subsequent permafrost destabilization causes thaw subsidence and thermokarst development. Because these processes are difficult to detect due to the lack of timely and accurate elevation datasets they have received not much attention, despite their potentially global significance through the permafrost carbon feedback. Thanks to remote sensing pioneering works in Alaska and Siberia, widespread thaw subsidence has been documented and is increasingly perceived as a potentially widespread permafrost landscape response to contemporary climate change. Clearly, however, detailed local inventories are required to calibrate regional long and short-term assessments for measuring surface deformation due to permafrost thaw. The objective of our study is to analyze time series of repeat terrestrial, air-, and space borne laser scanning (rLiDAR) for quantification of land surface lowering due to permafrost thaw, which is poorly resolved in terms of recent landscape development in the Arctic. Our work aims at finding commonalities and differences of change or no change on ground-ice-rich primary surfaces that are preserved as uplands, which cover 15 to 20% of the Teshekpuk Lake Special Area on the Arctic Coastal Plain of northern Alaska. Our approach focuses on quantifying modern thaw subsidence and thermokarst rates with high spatial resolution data over several decades as well as high temporal resolution data of inter-annual intervals. Multi-annual measurements of rLiDAR over Arctic Alaska have been made by aircraft in 2016 and in 2015+2017 through on-site surveys during field expeditions. These in situ data serve as a basis for large scale surface change assessments using time series of photogrammetrically derived elevation data from very high resolution historical aerial photographs and modern satellite imagery. The synergistic data fusion approach enhances permafrost degradation monitoring and better resolves surface deformation associated with thaw subsidence. The novel datasets also provide insights into previously unrecognized patterns of rapid permafrost thaw and related interconnections.

Global Tectonics of Enceladus: Numerical Model

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2016-10-01

Introduction: Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of 200 kg is ejected into space from the South Polar Terrain (SPT) - [1]. The loss of matter from the body's interior should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic process that could explain this paradox. Our hypotheses states that the mass loss from SPT is the main driving mechanism of the following tectonic processes: subsidence of SPT, flow in the mantle and motion of adjacent tectonic plates. The hypotheses is presented in [2], [3] and[4].We suggest that the loss of the volatiles results in a void, an instability, and motion of solid matter to fill the void. The motion is presented at the Fig.1 and includes:Subsidence of the 'lithosphere' of SPT.Flow of the matter in the mantle.Motion of plates adjacent to SPT towards the active regionMethods and results: The numerical model of processes presented is developed. It is based on the equations of continuous media..If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is 0.05 mmyr-1. However, numerical calculations indicate that all three types of motion are usually important. The role of a given motion depends on the viscosity distribution. Generally, for most of the models the subsidence is 0.02 mmyr-1, but mantle flow and plates' motion also play a role in filling the void. The preliminary results of the numerical model indicate also that the velocity of adjacent plates could be 0.02 mmyr-1 for the Newtonian rheology.Note that in our model the reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. The SPT does not have to be compressed, so the open "tiger stripes" could exist for long time. e suppose that it means the end of activity in the given region.

Mid-tertiary ash flow tuff cauldrons, southwestern New Mexico

NASA Technical Reports Server (NTRS)

Elston, W. E.

1984-01-01

Characteristics of 28 known or suspected mid-Tertiary ash-flow tuff cauldrons in New Mexico are described. The largest region is 40 km in diameter, and erosional and block faulting processes have exposed levels as far down as the plutonic roots. The study supports a five-stage process: precursor, caldera collapse, early post-collapse, volcanism, major ring-fracture volcanism, and hydrothermal activity. The stages can repeat or the process can stop at any stage. Post-collapse lavas fell into two categories: cauldron lavas, derived from shallow defluidized residues of caldera-forming ash flow tuff eruption, and framework lavas, evolved from a siliceous pluton below the cauldron complex. The youngest caldera was shallow and formed from asymmetric subsidence and collapse of the caldera walls.

Application of Differential InSAR to Mining

NASA Astrophysics Data System (ADS)

Eneva, M.; Baker, E.; Xu, H.

2001-12-01

In a NASA funded project we are applying differential InSAR to measure surface deformation associated with mining at depth. Surface displacement can be caused by rockbursts associated with mine collapse or mining-induced stress released on nearby tectonic features. The latter type of rockbursts are similar to tectonic earthquakes, but generally occur at shallower depths than non-induced events of similar size. Thus significant co-seismic surface changes may accompany them. In addition, subsidence of a more gradual type may result from ongoing soft-rock (e.g., coal, potash, salt) mining. While such subsidence can accidentally occur above abandoned mines, it is most often planned as part of the ongoing ore extraction, especially in so-called long-wall mining. Predicting the amount and spatial extent of this subsidence is an aspect of mining engineering. It is important to compare these predictions with measurements of the actual deformation. Although mines use leveling and GPS measurements to monitor subsidence, these are generally performed with much smaller frequency (e.g., annually) and lower spatial resolution than repeat-pass differential InSAR can provide. We are using ERS-1/2 raw SAR data provided by ESA and Eurimage, and the Gamma software for their processing. At present we are focused on the processing and modeling of data from two representative sites. By the end of the project we will have analyzed several more sites of subsidence and M>4.5 rockbursts. As an example of mining subsidence, we are currently analyzing data from the site of a coal mine in Colorado (USA), operating in a relatively flat and arid area. Numerous adjacent long-wall panels of extraction are used, some exceeding 5 km in length. A 600 to 750-m length of panel may be extracted per month, with a maximum subsidence of 1.5 to 1.8 m expected over each panel. The surface deformation can be monitored especially well during the summers of 1995 and 1996, when nine good-quality ERS-1/2 SAR scenes were gathered. Two of these scenes form a tandem pair to be used for topography. We are also making use of a 30-m DEM from USGS, maps of extraction panels, leveling data and microearthquake locations. As an example of rockbursts, we are presently analyzing ERS-2 SAR data from the site of a M5.1 rockburst that occurred on April 22, 1999, in the gold fields of Welkom, South Africa. The event was induced on a fault transecting the mine and had a normal mechanism. Only two good-quality SAR scenes are available from this site, spanning about a year including the event. Thus the topography effect cannot be removed using interferometry. However, since flat surface and urban environment characterize this site, a clear fringe pattern is observed, apparently associated with the rockburst. This pattern suggests up to 9-cm subsidence. Its center is within 5 km from the seismically determined event location. Thus this rockburst represents an example of the capabilities of InSAR to provide ground truth locations for moderate shallow earthquakes. To model the seismic source, we are using the RNGCHN software (Feigl and Dupré, 1999) based on analytic solutions for a homogeneous half-space. In order to model deformation in realistically complex crust, including layered structure and lateral heterogeneities, we are also developing a 3D finite-difference method of estimating deformation in a volume due to displacement on a fault surface. This method will be also used for the modeling of mining subsidence.

The relation between land use and subsidence in the Vietnamese Mekong delta.

PubMed

Minderhoud, P S J; Coumou, L; Erban, L E; Middelkoop, H; Stouthamer, E; Addink, E A

2018-09-01

The Vietnamese Mekong delta is subsiding due to a combination of natural and human-induced causes. Over the past several decades, large-scale anthropogenic land-use changes have taken place as a result of increased agricultural production, population growth and urbanization in the delta. Land-use changes can alter the hydrological system or increase loading of the delta surface, amplifying natural subsidence processes or creating new anthropogenic subsidence. The relationships between land use histories and current rates of land subsidence have so far not been studied in the Mekong delta. We quantified InSAR-derived subsidence rates for the various land-use classes and past land-use changes using a new, optical remote sensing-based, 20-year time series of land use. Lowest mean subsidence rates were found for undeveloped land-use classes, like marshland and wetland forest (~6-7mmyr -1 ), and highest rates for areas with mixed-crop agriculture and cities (~18-20mmyr -1 ). We assessed the relationship strength between current land use, land-use history and subsidence by predicting subsidence rates during the measurement period solely based on land-use history. After initial training of all land-use sequences with InSAR-derived subsidence rates, the land-use-based approach predicted 65-92% of the spatially varying subsidence rates within the measurement error range of the InSAR observations (RMSE=5.8mm). As a result, the spatial patterns visible in the observed subsidence can largely be explained by land use. We discuss in detail the dominant land-use change pathways and their indirect, causal relationships with subsidence. Our spatially explicit evaluation of these pathways provides valuable insights for policymakers concerned with land-use planning in both subsiding and currently stable areas of the Mekong delta and similar systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Long-term groundwater storage changes and land subsidence development in the North China Plain (1971-2015)

NASA Astrophysics Data System (ADS)

Gong, Huili; Pan, Yun; Zheng, Longqun; Li, Xiaojuan; Zhu, Lin; Zhang, Chong; Huang, Zhiyong; Li, Zhiping; Wang, Haigang; Zhou, Chaofan

2018-04-01

The North China Plain (NCP) has been suffering from groundwater storage (GWS) depletion and land subsidence for a long period. This paper collects data on GWS changes and land subsidence from in situ groundwater-level measurements, literature, and satellite observations to provide an overview of the evolution of the aquifer system during 1971-2015 with a focus on the sub-regional variations. It is found that the GWS showed a prolonged declining rate of -17.8 ± 0.1 mm/yr during 1971-2015, with a negative correlation to groundwater abstraction before year 2000 and a positive correlation after 2000. Statistical correlations between subsidence rate and the GWS anomaly (GWSA), groundwater abstraction, and annual precipitation show that the land subsidence in three sub-regions (Beijing, Tianjin, and Hebei) represents different temporal variations due to varying driver factors. Continuous drought caused intensive GWS depletion (-76.1 ± 6.5 mm/yr) and land subsidence in Beijing during 1999-2012. Negative correlations between total groundwater abstraction and land subsidence exhibited after the 1980s indicate that it may be questionable to infer subsidence from regional abstraction data. Instead, the GWSA generally provides a reliable correlation with subsidence. This study highlights the spatio-temporal variabilities of GWS depletion and land subsidence in the NCP under natural and anthropogenic impacts, and the importance of GWS changes for understanding land subsidence development.

Three-dimensional imaging, change detection, and stability assessment during the centerline trench levee seepage experiment using terrestrial light detection and ranging technology, Twitchell Island, California, 2012

USGS Publications Warehouse

Bawden, Gerald W.; Howle, James; Bond, Sandra; Shriro, Michelle; Buck, Peter

2014-01-01

A full scale field seepage test was conducted on a north-south trending levee segment of a now bypassed old meander belt on Twitchell Island, California, to understand the effects of live and decaying root systems on levee seepage and slope stability. The field test in May 2012 was centered on a north-south trench with two segments: a shorter control segment and a longer seepage test segment. The complete length of the trench area measured 40.4 meters (m) near the levee centerline with mature trees located on the waterside and landside of the levee flanks. The levee was instrumented with piezometers and tensiometers to measure positive and negative porewater pressures across the levee after the trench was flooded with water and held at a constant hydraulic head during the seepage test—the results from this component of the experiment are not discussed in this report. We collected more than one billion three-dimensional light detection and ranging (lidar) data points before, during, and after the centerline seepage test to assess centimeter-scale stability of the two trees and the levee crown. During the seepage test, the waterside tree toppled (rotated 20.7 degrees) into the water. The landside tree rotated away from the levee by 5 centimeters (cm) at a height of 2 m on the tree. The paved surface of the levee crown had three regions that showed subsidence on the waterside of the trench—discussed as the northern, central, and southern features. The northern feature is an elongate region that subsided 2.1 cm over an area with an average width of 1.35 m that extends 15.8 m parallel to the trench from the northern end of the trench to just north of the trench midpoint, and is associated with a crack 1 cm in height that formed during the seepage test on the trench wall. The central subsidence feature is a semicircular region on the waterside of the trench that subsided by as much as 6.2 cm over an area 3.4 m wide and 11.2 m long. The southern feature is an elongate region that has a maximum subsidence of 3.5 cm over an area 0.75 m wide and 8.1 m long and is associated with a number of small fractures in the pavement that are predominately north-south-trending and parallel to the trench. We determined that there was no significant motion of the levee flank during the last week of the seepage test. We also determined biomorphic parameters for the landside tree, such as the 3D positioning on the levee, tree height, levee parallel/perpendicular cross sectional area, and canopy centroid. These biomorphic parameters were requested to support a University of California Berkeley team studying seepage and stability on the levee. A gridded, 2-cm bare-earth digital elevation model of the levee crown and the landside levee flank from the final terrestrial lidar (T-Lidar) survey provided detailed topographic data for future assessment. Because the T-Lidar was not integrated into the project design, other than an initial courtesy dataset to help characterize the levee surface, our ability to contribute to the overall science goals of the seepage test was limited. Therefore, our analysis focused on developing data collection and processing methodology necessary to align ultra high-resolution T-Lidar data (with an average spot spacing 2–3 millimeters on the levee crown) from several instrument setup locations to detect, measure, and characterize dynamic centimeter-scale deformation and surface changes during the seepage test.

Mesoscale Features and Cloud Organization on 10-12 December 1978 over the South China Sea.

NASA Astrophysics Data System (ADS)

Warner, Charles

1982-07-01

Aircraft data from Winter MONEX have been combined with other data to study mesoscale features, and organization of cumulus clouds, on 10-12 December 1978. A moderate cold surge in the northeasterly monsoon flow, toward cloudiness in an equatorial trough off Borneo, peaked on 11 December.Clouds in the northeasterly monsoon flow were similar to those in the trades, with variations in convective regime on length scales on the order of 100 km. Marked mid-tropospheric subsidence was accompanied by low-level divergence near 20°N. During 10 December, anvil clouds near Borneo expanded; cumulus congestus and cumulonimbus formed on the periphery of this area. The approach of the low-level northeasterlies to the area of anvils was marked by a diminution of subsidence, conditional instability, and a weak field of low-level convergence, with randomly organized cumulus of increasing height. A low-level easterly jet was found in this transition zone, downstream from cloudiness over the Philippines. South of Vietnam, a clear area was associated with low air temperatures, and not subsidence. Congestus and cumulonimbus clouds formed near the eastern coast of the Malay Peninsula.Cloud streets were seen from latitude 19°N to the Malaysian coast (with a break south of Vietnam). These clouds were confined below the level of an inflection point in the profile of winds normal to the street direction. Greatest spacings of streets occurred with greatest vertical shears of the cross-winds. Cloud number densities were more closely related to the instability of the vertical stratification than to any other parameter.Cross-wind organization of clouds occurred in circumstances of unstable, stratification and apparently of net ascent. Alignment of clouds was at an angle to the directions of both winds and vertical wind shears. It is inferred that when convergence was strong, deep clouds occurred along lines of convergence in the surface streamlines.

Fernandina caldera collapse morphology in geometric and dynamic comparison to sandbox models, subsidence sinks over nuclear-explosion cavities, and some other calderas

NASA Astrophysics Data System (ADS)

Howard, K. A.

2009-12-01

The 1968 collapse structure of Fernandina caldera (1.5 km3 collapsed) and also the smaller Darwin Bay caldera in Galápagos each closely resembles morphologically the structural zoning of features found in depressions collapsed into nuclear-explosion cavities (“sinks” of Houser, 1969) and in coherent sandbox-collapse models. Coherent collapses characterized by faulting, folding, and organized structure contrast with spalled pit craters (and lab experiments with collapsed powder) where disorganized piles of floor rubble result from tensile failure of the roof. Subsidence in coherent mode, whether in weak sand in the lab, stronger desert alluvium for nuclear-test sinks, or in hard rock for calderas, exhibits consistent morphologic zones. Characteristically in the sandbox and the nuclear-test analogs these include a first-formed central plug that drops along annular reverse faults. This plug and a surrounding inward-tilted or monoclinal ring (hanging wall of the reverse fault) contract as the structure expands outward by normal faulting, wherein peripheral rings of distending material widen the upper part of the structure along inward-dipping normal faults and compress inner zones and help keep them intact. In Fernandina, a region between the monocline and the outer zone of normal faulting is interpreted, by comparison to the analogs, to overlie the deflation margin of an underlying magma chamber. The same zoning pattern is recognized in structures ranging from sandbox subsidence features centimeters across, to Alae lave lake and nuclear-test sinks tens to hundreds of meters across, to Fenandina’s 2x4 km-wide collapse, to Martian calderas tens of kilometers across. Simple dimensional analysis using the height of cliffs as a proxie for material strength implies that the geometric analogs are good dynamic analogs, and validates that the pattern of both reverse and normal faulting that has been reported consistently from sandbox modeling applies widely to calderas.

[Subsidized project of hearing aid purchase for mild-moderate hearing impaired children in Akita prefecture].

PubMed

Sato, Teruyuki; Nakazawa, Misao; Takahashi, Shin; Ishikawa, Kazuo

2013-06-01

The dissemination of newborn hearing screening has detected children with mild-moderate hearing impairment at an early age. However, there is no nation-wide welfare system for children with mild-moderate hearing impairment in Japan. Under these kinds of social conditions, a subsidized project of hearing aid purchase for mild-moderate hearing impaired children has come into force from April 2010 in Akita prefecture. All 18 candidates who applied for this project were subsidized in Akita prefecture. Eighteen children purchased their hearing aids using this subsidy. The feature of this project was that every child could have access to subsidies as long as their doctor recognized the effectiveness of hearing aids because children with hearing impairment need to learn language. They contacted the hospital, prefectural government and institutes related to hearing loss before this project come into force. We recognized parents who are raising a child with mild-moderate hearing impairment have high interest in this project. Hearing aids can represent a considerable expense for young parents who are raising a child. We encountered some children who had to give up the idea of hearing aids due to their parents' economic circumstances before this project become effective. These situations were completely avoided after this project came into being. This administrative purpose was of demonstrated value in children with mild-moderate hearing impairment.

Emergence and evolution of Santa Maria Island (Azores)—The conundrum of uplifted islands revisited

USGS Publications Warehouse

Ramalho, Ricardo; Helffrich, George; Madeira, Jose; Cosca, Michael A.; Thomas, Christine; Quartau, Rui; Hipolito, Ana; Rovere, Alessio; Hearty, Paul; Avila, Sergio

2017-01-01

The growth and decay of ocean-island volcanoes are intrinsically linked to vertical movements. While the causes for subsidence are better understood, uplift mechanisms remain enigmatic. Santa Maria Island in the Azores Archipelago is an ocean-island volcano resting on top of young lithosphere, barely 480 km away from the Mid-Atlantic Ridge. Like most other Azorean islands, Santa Maria should be experiencing subsidence. Yet, several features indicate an uplift trend instead. In this paper, we reconstruct the evolutionary history of Santa Maria with respect to the timing and magnitude of its vertical movements, using detailed field work and 40Ar/39Ar geochronology. Our investigations revealed a complex evolutionary history spanning ∼6 m.y., with subsidence up to ca. 3.5 Ma followed by uplift extending to the present day. The fact that an island located in young lithosphere experienced a pronounced uplift trend is remarkable and raises important questions concerning possible uplift mechanisms. Localized uplift in response to the tectonic regime affecting the southeastern tip of the Azores Plateau is unlikely, since the area is under transtension. Our analysis shows that the only viable mechanism able to explain the uplift is crustal thickening by basal intrusions, suggesting that intrusive processes play a significant role even on islands standing on young lithosphere, such as in the Azores.

Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry

USGS Publications Warehouse

Lu, Z.; Wicks, C.; Kwoun, O.; Power, J.A.; Dzurisin, D.

2005-01-01

In March 1996, an intense earthquake swarm beneath Akutan Island, Alaska, was accompanied by extensive ground cracking but no eruption of Akutan volcano. Radar interferograms produced from L-band JERS-1 and C-band ERS-1/2 images show uplift associated with the swarm by as much as 60 cm on the western part of the island. The JERS-1 interferogram has greater coherence, especially in areas with loose surface material or thick vegetation. It also shows subsidence of similar magnitude on the eastern part of the island and displacements along faults reactivated during the swarm. The axis of uplift and subsidence strikes about N70??W, which is roughly parallel to a zone of fresh cracks on the northwest flank of the volcano, to normal faults that cut the island and to the inferred maximum compressive stress direction. A common feature of models that fit the deformation is the emplacement of a shallow dike along this trend beneath the northwest flank of the volcano. Both before and after the swarm, the northwest flank was uplifted 5-20 mm/year relative to the southwest flank, probably by magma intrusion. The zone of fresh cracks subsided about 20 mm during 1996-1997 and at lesser rates thereafter, possibly because of cooling and degassing of the intrusion. ?? 2005 CASI.

Impacts of 25 years of groundwater extraction on subsidence ...

EPA Pesticide Factsheets

Many major river deltas in the world are subsiding and consequently become increasingly vulnerable to flooding and storm surges, salinization and permanent inundation. For the Mekong Delta, annual subsidence rates up to several centimetres have been reported. Excessive groundwater extraction is suggested as the main driver. As groundwater levels drop, subsidence is induced through aquifer compaction. Over the past 25 years, groundwater exploitation has increased dramatically, transforming the delta from an almost undisturbed hydrogeological state to a situation with increasing aquifer depletion. Yet the exact contribution of groundwater exploitation to subsidence in the Mekong delta has remained unknown. In this study we deployed a delta-wide modelling approach, comprising a 3D hydrogeological model with an integrated subsidence module. This provides a quantitative spatially-explicit assessment of groundwater extraction-induced subsidence for the entire Mekong delta since the start of widespread overexploitation of the groundwater reserves. We find that subsidence related to groundwater extraction has gradually increased in the past decades with highest sinking rates at present. During the past 25 years, the delta sank on average ~18 cm as a consequence of groundwater withdrawal. Current average subsidence rates due to groundwater extraction in our best estimate model amount to 1.1 cm yr−1, with areas subsiding over 2.5 cm yr−1, outpacing global sea level ri

Monitoring ground subsidence in Shanghai maglev area using two kinds of SAR data

NASA Astrophysics Data System (ADS)

Wu, Jicang; Zhang, Lina; Chen, Jie; Li, Tao

2012-11-01

Shanghai maglev is a very fast traffic tool, so it is very strict with the stability of the roadbed. However, the ground subsidence is a problem in Shanghai because of the poor geological condition and human-induced factors. So it is necessary to monitor ground subsidence in the area along the Shanghai maglev precisely and frequently. Traditionally, a precise levelling method is used to survey along the track. It is expensive and time consuming, and can only get the ground subsidence information on sparse benchmarks. Recently, the small baseline differential SAR technique plays a valuable part in monitoring ground subsidence, which can extract ground subsidence information with high spatial resolution in a wide area. In this paper, L-band ALOS PALSAR data and C-band Envisat ASAR data are used to extract ground subsidence information using the SBAS method in the Shanghai maglev area. The results show that the general pattern of ground subsidence from InSAR processing of two differential bands of SAR images is similar. Both results show that there is no significant ground subsidence on the maglev line. Near the railway line, there are a few places with subsidence rates at about -20 mm/y or even more, such as Chuansha town, the junction of the maglev and Waihuan road.

Land subsidence and relative sea-level rise in the southern Chesapeake Bay region

USGS Publications Warehouse

Eggleston, Jack; Pope, Jason

2013-01-01

The southern Chesapeake Bay region is experiencing land subsidence and rising water levels due to global sea-level rise; land subsidence and rising water levels combine to cause relative sea-level rise. Land subsidence has been observed since the 1940s in the southern Chesapeake Bay region at rates of 1.1 to 4.8 millimeters per year (mm/yr), and subsidence continues today. This land subsidence helps explain why the region has the highest rates of sea-level rise on the Atlantic Coast of the United States. Data indicate that land subsidence has been responsible for more than half the relative sea-level rise measured in the region. Land subsidence increases the risk of flooding in low-lying areas, which in turn has important economic, environmental, and human health consequences for the heavily populated and ecologically important southern Chesapeake Bay region. The aquifer system in the region has been compacted by extensive groundwater pumping in the region at rates of 1.5- to 3.7-mm/yr; this compaction accounts for more than half of observed land subsidence in the region. Glacial isostatic adjustment, or the flexing of the Earth’s crust in response to glacier formation and melting, also likely contributes to land subsidence in the region.

Land subsidence caused by withdrawal of oil and gas in the Gulf coastal plain - The Houston, Texas, case history

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holzer, T.L.

1990-09-01

The extensive network of geodetic leveling lines in the Houston-Galveston, Texas, area, where at least 110 oil and gas fields have been developed, provides the most comprehensive opportunity in the Gulf Coast to search for the occurrence of land subsidence caused by withdrawal of oil and gas. Although the evaluation is complicated by regional subsidence caused by a decline of ground-water level in aquifers beneath the area, subsidence caused by oil and gas withdrawal can be examined by searching for local increases of subsidence at oil and gas fields crossed by leveling lines. Twenty-nine fields are crossed by lines withmore » repeated leveling surveys. Subsidence profiles across these fields indicate local increases of subsidence at six fields-Alco-Mag, Chocolate Bayou, Goose Creek, Hastings, Mykawa, and South Houston. Although ground-water withdrawal is undoubtedly the most important factor contributing to the total subsidence at each field, oil and gas withdrawal may be partly responsible for the local increases. Except for Chocolate Bayou, the volume of petroleum production at each field was sufficient to account for the increase. The volume of petroleum production, however, in general is not a reliable index for predicting the local increase because land within many fields with significant production did not show local increases of subsidence. With the exception of the 1 m subsidence caused by petroleum withdrawal at Goose Creek (1917-1925), local increases of subsidence were less than 0.3 m.« less

Late 20th Century Deep-seated Vertical Motions in New Orleans and implications for Gulf Coast Subsidence

NASA Astrophysics Data System (ADS)

Dokka, R. K.

2010-12-01

Subsidence of the Mississippi River delta and adjoining coastal areas is widely thought to be dominated by compaction of Holocene sediments. Current public policies regarding hurricane protection and ecosystems restoration are founded on this interpretation. To test this hypothesis, monuments that penetrate the entire Holocene section were measured using geodetic leveling and water gauges attached to bridge foundations. Results show that the entire sampling area subsided between 1955 and 1995 in amounts unanticipated by previous models. Subsidence due to processes originating below the Holocene section locally exceeded 0.9 m between 1955 and 1995. The maxima of deep subsidence occurred in the urbanized and industrialized sections of eastern New Orleans. Subsidence decreased away from urbanized areas and north of the belt of active basin margin normal faults; this decrease in subsidence continued to the north and east along the Mississippi coast. These independent measurements provide insights into the complexity and causes of modern landscape change in the region. Modern subsidence is clearly not dominated solely by shallow processes such as natural compaction, Deep subsidence occurring east and north of the basin margin faults can be explained by regional tectonic loading of the lithosphere by the modern Mississippi River delta and local groundwater withdrawal. Sharp, local changes in subsidence coincide with strands of the basin margin normal fault system. Deep subsidence of the New Orleans area can be explained by a combination of groundwater withdrawal from shallow upper Pleistocene aquifers, the aforementioned lithospheric loading, and non-groundwater-related faulting. Subsidence due to groundwater extraction from aquifers ~160 to 200 m deep dominated the urbanized areas from ~1960 to the early 1990s and is likely responsible for lowering flood protection structures and bridges in the area by as much as ~0.8 m.

Structural evolution of Cenozoic basins in northeastern Tunisia, in response to sinistral strike-slip movement on the El Alia-Teboursouk Fault

NASA Astrophysics Data System (ADS)

Bejaoui, Hamida; Aïfa, Tahar; Melki, Fetheddine; Zargouni, Fouad

2017-10-01

This paper resolves the structural complexity of Cenozoic sedimentary basins in northeastern Tunisia. These basins trend NE-SW to ∼ E-W, and are bordered by old fracture networks. Detailed descriptions of the structural features in outcrop and in subsurface data suggest that the El Alia-Teboursouk Fault zone in the Bizerte area evolved through a series of tectonic events. Cross sections, lithostratigraphic correlations, and interpretation of seismic profiles through the basins show evidence for: (i) a Triassic until Jurassic-Early Cretaceous rifting phase that induced lateral variations of facies and strata thicknesses; (ii) a set of faults oriented NE-SW, NW-SE, N-S, and E-W that guided sediment accumulation in pull-apart basins, which were subject to compressive and transpressive deformation during Eocene (Lutetian-Priabonian), Miocene (Tortonian), and Pliocene-Quaternary; and (iii) NNW-SSE to NS contractional events that occurred during the Late Pliocene. Part of the latest phase has been the formation of different synsedimentary folded structures with significant subsidence inversion. Such events have been responsible for the reactivation of inherited faults, and the intrusion of Triassic evaporites, ensuring the role of a slip layer. The combined effects of the different paleoconstraints and halokinetic movements are at the origin of the evolution of these pull-apart basins. The subsurface data suggest that an important fault displacement occurred during the Mesozoic-Cenozoic. The patterns of sediment accumulation in the different basins reflect a high activity of deep ancient faults.

Hydrogeology and simulation of groundwater flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system, Texas, 1891-2009

USGS Publications Warehouse

Kasmarek, Mark C.

2012-01-01

The MODFLOW-2000 groundwater flow model described in this report comprises four layers, one for each of the hydrogeologic units of the aquifer system except the Catahoula confining system, the assumed no-flow base of the system. The HAGM is composed of 137 rows and 245 columns of 1-square-mile grid cells with lateral no-flow boundaries at the extent of each hydrogeologic unit to the northwest, at groundwater divides associated with large rivers to the southwest and northeast, and at the downdip limit of freshwater to the southeast. The model was calibrated within the specified criteria by using trial-and-error adjustment of selected model-input data in a series of transient simulations until the model output (potentiometric surfaces, land-surface subsidence, and selected water-budget components) acceptably reproduced field measured (or estimated) aquifer responses including water level and subsidence. The HAGM-simulated subsidence generally compared well to 26 Predictions Relating Effective Stress to Subsidence (PRESS) models in Harris, Galveston, and Fort Bend Counties. Simulated HAGM results indicate that as much as 10 feet (ft) of subsidence has occurred in southeastern Harris County. Measured subsidence and model results indicate that a larger geographic area encompassing this area of maximum subsidence and much of central to southeastern Harris County has subsided at least 6 ft. For the western part of the study area, the HAGM simulated as much as 3 ft of subsidence in Wharton, Jackson, and Matagorda Counties. For the eastern part of the study area, the HAGM simulated as much as 3 ft of subsidence at the boundary of Hardin and Jasper Counties. Additionally, in the southeastern part of the study area in Orange County, the HAGM simulated as much as 3 ft of subsidence. Measured subsidence for these areas in the western and eastern parts of the HAGM has not been documented.

Modeling Recent Subsidence of Mars' Olympus Mons Using Lava Flows as Paleo-Slope Indicators

NASA Astrophysics Data System (ADS)

Simpson, M.; Reeves, A.; Chadwick, J.; McGovern, P. J.

2013-12-01

Olympus Mons is an enormous volcanic edifice on Mars with a basal diameter over 600 km and a height of 23 km. In spite of this size, no indications of subsidence, such as an obvious topographic moat, have previously been detected around the volcano. In this study, we mapped the orientations of long, thin lava flows on the plains to the south and southeast of Olympus Mons using 100m-resolution imagery from the Thermal Emission Imaging System (THEMIS) on Mars Odyssey, and topography using Mars Orbiter Laser Altimeter (MOLA) data from Mars Global Surveyor. The results show that the flows are no longer oriented in a downhill direction, consistently deviating from modern slope vectors in a counterclockwise direction by 21.4 × 10.8 degrees (n = 65). The configuration of this misalignment between modern and paleo-topography is consistent with subsidence centered on the volcano in the time since the flows were emplaced. Our preliminary geophysical modeling used a range of load volumes, load radii, and lithospheric thicknesses to identify the scenario required to best restore modern topography to match the paleo-topography present when the lava flows were emplaced (i.e. 'uplift' Olympus Mons until the lava flows on the surrounding plains are restored to a downhill direction). The results show that lithospheric subsidence of about 1.2 km due to the magmatic addition of 3.8x10^5 km^3 best fits the observed topographic changes. Load center heights of 1 to 8 km were considered, with best fits generally in the 3-5 km range. Best-fit elastic lithosphere thickness (Te) values were generally 100 km or greater, consistent with estimates for Te from loading models [1,2] and gravity-topography relationships [3,4,5]. Our new crater size-density measurements of the plains in the study area show that the observed subsidence occurred within the past 229 × 26 my. Previous crater counts for Olympus Mons calderas and lower flank flows [6] reveal volcanic activity clustered around 100-200 Myr ago and as young as 2.5 Myr ago, and young faulting of the Olympus Mons edifice suggests recent flank spreading [7]. These young features are consistent with the evidence for recent magmatic loading and subsidence found in this study. REFERENCES: [1] Thurber and Toksoz, 1978; [2] Comer et al., 1985; [3] McGovern et al., 2002, [4] McGovern et al., 2004; [5] Belleguic et al., 2005; [6] Neukum et al 2004; [7] Basilevsky et al., 2006.

Influence the condition land subsidence and groundwater impact of Jakarta coastal area

NASA Astrophysics Data System (ADS)

Rahman, S.; Sumotarto, U.; Pramudito, H.

2018-01-01

Jakarta has been experiencing land subsidence for ten years due toerecting weight building and intensive extraction of groundwater for society drink water through ground water wells. Many groundwater extraction for drinkingwater has caused intensive scouring of land rock and further triggering land subsidence developed widely in coastal area of Jakarta. Measurement of the land subsidence has been performed by various experts and institutes. Between 1974 to 2010 subsidence has happened between 3 to 4.1 meters especially in Jakarta coastal area. Two major causes of the subsidence are identified. The first major cause is a result of erecting weight building such as hotels, appartments, and various human activities buildings. The second major cause is extracting ground water from aquifers bellow Jakarta land due to water deep wells down to the aquifer and traditional shallow water well of shallow or subsurface uncovered ground water. Weighter building and higher debit of water flow from deep water wells has fastened and deepened the land subsidence. Continuous measurement of land subsidence by means of geodetic as well as geophysical earth behaviour measurements need to be performed to monitor the rate, location as well as mapping of the land subsidence.

[Research on monitoring land subsidence in Beijing plain area using PS-InSAR technology].

PubMed

Gu, Zhao-Qin; Gong, Hui-Li; Zhang, You-Quan; Lu, Xue-Hui; Wang, Sa; Wang, Rong; Liu, Huan-Huan

2014-07-01

In the present paper, the authors use permanent scatterers synthetic aperture radar interferometry (PS-InSAR) technique and 29 acquisitions by Envisat during 2003 to 2009 to monitor and analyze the spatial-temporal distribution and mechanism characterize of land subsidence in Beijing plain area. The results show that subsidence bowls have been bounded together in Beijing plain area, which covers Chaoyang, Changping, Shunyi and Tongzhou area, and the range of subsidence has an eastward trend. The most serious regional subsidence is mainly distributed by the quaternary depression in Beijing plain area. PS-Insar results also show a new subsidence bowl in Pinggu. What's more, the spatial and temporal distribution of deformation is controlled mainly by faults, such as Liangxiang-Shunyi fault, Huangzhuang-Gaoliying fault, and Nankou-Sunhe fault. The subsidence and level of groundwater in study area shows a good correlation, and the subsidence shows seasonal ups trend during November to March and seasonal downs trend during March to June along with changes in groundwater levels. The contribution of land subsidence is also influenced by stress-strain behavior of aquitards. The compaction of aquitards shows an elastic, plastic, viscoelastic pattern.

Modeling Subsidence-Like Events on Cometary Nuclei

NASA Astrophysics Data System (ADS)

Rosenberg, Eric; Prialnik, Dina

2017-10-01

There is ample evidence, particularly from the Rosetta mission, that cometary nuclei have very low tensile strength. Consequently, morphological changes are expected to occur, caused by buildup of pressure due to gas release in the interior of the nucleus. Such changes have been observed on the surface of comet 67P/Churyumov-Gerasimenko, as reported for example by Groussin et al.(2015). A mechanism for explaining comet surface depressions has been recently proposed by Prialnik & Sierks (2017). Here we report on a numerical study, elaborating on this mechanism. Essentially, the model considers a cometary nucleus composed of a low-density mixture of ice and dust, assuming that the ice is amorphous and traps volatile gasses, such as CO and CO2. The model assumes that the tensile strength of the subsurface material is low and that the surface is covered by a thin crust of low permeability. As the comet evolves, the amorphous ice crystallizes, and the crystallization front recedes from the surface, releasing the trapped gasses, which accumulate beneath the surface, building up pressure. The gas pressure weakens the material strength, but sustains the gas-filled layer against hydrostatic pressure. Eventually, the gas will break its way through the outer crust in an outburst. The rapid pressure drop may cause the collapse of the gas depleted layer, as seen on the nucleus of 67P/Churyumov-Gerasimenko. This mechanism is similar to subsidence events in gas fields on earth.We have performed quasi-3D numerical simulations in an attempt to determine the extent of the area that would be affected by such a mechanism. The frequency of such subsidence events and the depth of the collapse are investigated as functions of solar angle and spin axis inclination. The necessary conditions for outburst-induced collapse are determined and confronted with observations.References:Groussin, O., Sierks, H., et al. 2015, A&A, 583, A35Prialnik, D. & Sierks, H., 2017, MNRAS, in press

Unexpected hydrologic perturbation in an abandoned underground coal mine: Response to surface reclamation?

USGS Publications Warehouse

Harper, D.; Olyphant, G.A.; Hartke, E.J.

1990-01-01

A reclamation project at the abandoned Blackhawk Mine site near Terre Haute, Indiana, lasted about four months and involved the burial of coarse mine refuse in shallow (less than 9 m) pits excavated into loess and till in an area of about 16 ha. An abandoned flooded underground coal mine underlies the reclamation site at a depth of about 38 m; the total area underlain by the mine is about 10 km2. The potentiometric levels associated with the mine indicate a significant (2.7 m) and prolonged perturbation of the deeper confined groundwater system; 14 months after completing reclamation, the levels began to rise linearly (at an average rate of 0.85 cm/d) for 11 months, then fell exponentially for 25 months, and are now nearly stable. Prominent subsidence features exist near the reclamation site. Subsidence-related fractures were observed in cores from the site, and such fractures may have provided a connection between the shallower and deeper groundwater systems. ?? 1990 Springer-Verlag New York Inc.

Sinking coastal cities

NASA Astrophysics Data System (ADS)

Erkens, Gilles; Bucx, Tom; Dam, Rien; De Lange, Ger; Lambert, John

2014-05-01

In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs. This effects roads and transportation networks, hydraulic infrastructure - such as river embankments, sluice gates, flood barriers and pumping stations -, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annually. Excessive groundwater extraction after rapid urbanization and population growth is the main cause of severe land subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick sequences of soft soil. Because of ongoing urbanization and population growth in delta areas, in particular in coastal megacities, there is, and will be, more economic development in subsidence-prone areas. The impacts of subsidence are further exacerbated by extreme weather events (short term) and rising sea levels (long term).Consequently, detrimental impacts will increase in the near future, making it necessary to address subsidence related problems now. Subsidence is an issue that involves many policy fields, complex technical aspects and governance embedment. There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies and measures that are effective and efficient on both the short and long term. Urban (ground)water management, adaptive flood risk management and related spatial planning strategies are just examples of the options available. A major rethink is needed to deal with the 'hidden' but urgent threat of subsidence. As subsidence is spatially different and can be caused by multi processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes, how much is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

Evolving Landscapes: the Effect of Genetic Variation on Salt Marsh Erosion

NASA Astrophysics Data System (ADS)

Bernik, B. M.; Blum, M. J.

2014-12-01

Ecogeomorphic studies have demonstrated that biota can exert influence over geomorphic processes, such as sediment transport, which in turn have biotic consequences and generate complex feedbacks. However, little attention has been paid to the potential for feedback to arise from evolutionary processes as population genetic composition changes in response to changing physical landscapes. In coastal ecosystems experiencing land loss, for example, shoreline erosion entails reduced plant survival and reproduction, and thereby represents a geomorphic response with inherent consequences for evolutionary fitness. To get at this topic, we examined the effect of genetic variation in the saltmarsh grass Spartina alterniflora, a renowned ecosystem engineer, on rates of shoreline erosion. Field transplantation studies and controlled greenhouse experiments were conducted to compare different genotypes from both wild and cultivated populations. Plant traits, soil properties, accretion/subsidence, and rates of land loss were measured. We found significant differences in rates of erosion between field plots occupied by different genotypes. Differences in erosion corresponded to variation in soil properties including critical shear stress and subsidence. Plant traits that differed across genotypes included belowground biomass, root tensile strength, and C:N ratios. Our results demonstrate the importance of genetic variation to salt marsh functioning, elucidating the relationship between evolutionary processes and ecogeomorphic dynamics in these systems. Because evolutionary processes can occur on ecological timescales, the direction and strength of ecogeomorphic feedbacks may be more dynamic than previously accounted for.

State and local response to damaging land subsidence in United States urban areas

USGS Publications Warehouse

Holzer, T.L.

1989-01-01

Land subsidence caused by man-induced depressuring of underground reservoirs has occurred in at least nine urban areas in the United States. Significant efforts to control it have been made in three areas: Long Beach, California; Houston-Galveston, Texas; and Santa Clara Valley, California. In these areas coastal flooding and its control cost more than $300 million. Institutional changes were required in each area to ameliorate its subsidence problem. In Long Beach and Houston Galveston, efforts were made to mitigate subsidence only after significant flood damage had occurred. To arrest subsidence at Long Beach, the city lobbied for a special state law, the California Subsidence Act, that required unitization and repressuring of the Wilmington oil field. In the Houston-Galveston region, the Texas State Legislature authorized formation of the Harris-Galveston Coastal Subsidence District with authority to regulate groundwater pumping by permit. This solution, which was achieved through efforts of entities affected by subsidence, was the product of a series of compromises necessitated by political fragmentation and disjointed water planning in the region. Amelioration of subsidence in the Santa Clara Valley was a collateral benefit from the effort by water users to curtail ground-water overdraft in the valley. Importation of surface water and a tax on ground-water pumpage reduced ground-water use, thereby allowing the recovery of water level and the arresting of subsidence.

Megathrust earthquakes in Japan and Chile triggered multiple volcanoes to subside

NASA Astrophysics Data System (ADS)

Takada, Y.; Pritchard, M. E.; Fukushima, Y.; Jay, J.; Aron, F. A.; Henderson, S.; Lara, L. E.

2012-12-01

With spaceborne interferometric synthetic aperture radar (InSAR) analysis, we found that two recent megathrust earthquakes, the 2011 Mw 9.0 Tohoku earthquake in Japan (March 11, 2011) and the 2010 Mw 8.8 Maule earthquake in Chile (February 27, 2010), have triggered unprecedented subsidence of multiple volcanoes. There are strong similarities in the characteristics of the surface deformation in Chile and Japan; (1) the maximum amount of subsidence is about 15 cm, (2) the shape of subsidence areas exhibit elliptic shape elongated in the North-South direction -- perpendicular to the principal axis of the extensional stress change, and (3) most of the subsidence was aseismic. These similarities imply that volcanic subsidence from megathrust earthquakes is a ubiquitous phenomenon. In both areas, we found that hydro-thermal reservoirs (including water, gas, and possibly magma) would play key roles in the subsidence. Further continuous monitoring is necessary to determine if the surface subsidence leads to additional volcanic unrest. For the 2011 Tohoku Earthquake, we used SAR data acquired before and after the mainshock by ALOS (PALSAR). By removing long wave-length phase trend from InSAR images, we obtained the localized subsidence signals at five active volcanoes: Mt. Akitakoma, Mt. Kurikoma region, Mt. Zao, Mt. Azuma, and Mt. Nasu. All of them belong to the volcanic front of Northeast Japan and so they are among the closest volcanoes to the earthquake. The maximum amount of subsidence reaches 15 cm at Mt. Azuma. GPS data from two volcanoes also indicate surface subsidence consistent with the satellite radar observations. Furthermore, the GPS data show that the subsidence occurred immediately after the earthquake. According to numerical modelling, the observed subsidence can be explained by the co-seismic response of fluid-filled ellipsoid with horizontal dimensions of 10-40 × 5-15 km beneath each volcano. For the 2010 Maule Earthquake, we extracted the localized volcanic subsidence in the same manner as Japan by removing the earthquake deformation signature. Most interferograms were created from ALOS data, but several were from ENVISAT and ERS-2. We find subsidence at five volcanic areas: Caldera del Atuel, Tinguiririca, Calabozos caldera, Cerro Azul, and Nevados de Chillán. All of these regions belong to the Andean Southern Volcanic Zone, and are located within the 400 km long rupture area of the Maule earthquake. In three of the five subsiding regions, there are known geothermal reservoirs. The orientation of N-S elongated subsidence areas can be explained by underlying hydrothermal and/or magmatic system and increase in the number of small cracks around those systems due to the coseismic stress disturbance. Existence of such damage zone would make water and/or gas emissions efficient, and enhanced the N-S elongated surface subsidence. Increases in stream flow at the date of Maule earthquake were observed, although the fluid contribution from the volcanic areas is not the only or necessarily the primary source.

Three-dimensional numerical modeling of land subsidence in Shanghai, China

NASA Astrophysics Data System (ADS)

Ye, Shujun; Luo, Yue; Wu, Jichun; Yan, Xuexin; Wang, Hanmei; Jiao, Xun; Teatini, Pietro

2016-05-01

Shanghai, in China, has experienced two periods of rapid land subsidence mainly caused by groundwater exploitation related to economic and population growth. The first period occurred during 1956-1965 and was characterized by an average land subsidence rate of 83 mm/yr, and the second period occurred during 1990-1998 with an average subsidence rate of 16 mm/yr. Owing to the establishment of monitoring networks for groundwater levels and land subsidence, a valuable dataset has been collected since the 1960s and used to develop regional land subsidence models applied to manage groundwater resources and mitigate land subsidence. The previous geomechanical modeling approaches to simulate land subsidence were based on one-dimensional (1D) vertical stress and deformation. In this study, a numerical model of land subsidence is developed to simulate explicitly coupled three-dimensional (3D) groundwater flow and 3D aquifer-system displacements in downtown Shanghai from 30 December 1979 to 30 December 1995. The model is calibrated using piezometric, geodetic-leveling, and borehole extensometer measurements made during the 16-year simulation period. The 3D model satisfactorily reproduces the measured piezometric and deformation observations. For the first time, the capability exists to provide some preliminary estimations on the horizontal displacement field associated with the well-known land subsidence in Shanghai and for which no measurements are available. The simulated horizontal displacements peak at 11 mm, i.e. less than 10 % of the simulated maximum land subsidence, and seems too small to seriously damage infrastructure such as the subways (metro lines) in the center area of Shanghai.

How to deal with subsidence in the Dutch delta?

NASA Astrophysics Data System (ADS)

Stouthamer, Esther; Erkens, Gilles

2017-04-01

In many deltas worldwide subsidence still is an underestimated problem, while the threat posed by land subsidence to low-lying urbanizing and urbanized deltas exceeds the threat of sea-level rise induced by climate change. Human-induced subsidence is driven by the extraction of hydrocarbons and groundwater, drainage of phreatic groundwater, and loading by buildings and infrastructure. The consequences of subsidence are increased flood risk and flood water depth, rising groundwater levels relative to the land surface, land loss, damage to buildings and infrastructure, and salinization of ground and surface water.. The Netherlands has a long history of subsidence. Large-scale drainage of the extensive peatlands in the western and northern parts of the Netherlands started approximately 1000 years ago as a result of rapid population growth. Subsidence is still ongoing due to (1) continuous drainage of the former peatland, which is now mainly in use as agricultural land and built-up area, (2) expansion of the built-up area and the infrastructural network, (3) salt mining and the extraction of gas in the northern Netherlands. Mitigating subsidence and its negative impacts requires understanding of the relative contribution of the drivers contributing to total subsidence, accurate predictions of land subsidence under different management scenarios, and its impacts. Such understanding enables the development of effective and sustainable management strategies. In the Netherlands, a lot of effort is put into water management aiming at amongst others the protection against floods and the ensuring agricultural activities, but a specific policy focusing on subsidence is lacking. The development of strategies to cope with subsidence is very challenging, because (1) the exact contribution of different drivers of subsidence to total subsidence is spatially different within the Netherlands, (2) there is no single problem owner, which makes it difficult to recognize this a common societal issue that should be tackled, and (3) it requires an integrated approach involving technical knowledge on contributors to subsidence, water management, governance arrangements, the legislative framework, socio-economic developments and spatial planning. To develop a sustainable solution to subsidence, we propose an approach including: (1) monitoring of surface elevation and drivers of subsidence, (2) scenario studies using coupled state-of-the-art 3D geological, hydrological and subsidence numerical models , and (3) a national database and model infrastructure. The next step is to carry out (4) a societal cost-benefit analysis and (5) to optimize governance arrangements and the legislative framework enabling the (6) implementation of measures. The realization of these requirements and the implementation of the resulting management strategies requires a joint effort of the national research institutes, including universities, and the involved local, and regional governmental organizations controlled by the national government. The research institutes should be responsible for developing monitoring strategies, generating the data and databases and developing the numerical models, governance arrangements and the legislative framework. The governmental organizations have the important responsibility for putting subsidence on their agendas, facilitating the research institutes and the implementation of governance arrangements and legislative framework enabling the implementation of effective measures.

Regional subsidence history and 3D visualization with MATLAB of the Vienna Basin, central Europe

NASA Astrophysics Data System (ADS)

Lee, E.; Novotny, J.; Wagreich, M.

2013-12-01

This study reconstructed the subsidence history by the backstripping and 3D visualization techniques, to understand tectonic evolution of the Neogene Vienna Basin. The backstripping removes the compaction effect of sediment loading and quantifies the tectonic subsidence. The amount of decompaction was calculated by porosity-depth relationships evaluated from seismic velocity data acquired from two boreholes. About 100 wells have been investigated to quantify the subsidence history of the Vienna Basin. The wells have been sorted into 10 groups; N1-4 in the northern part, C1-4 in the central part and L1-2 in the northernmost and easternmost parts, based on their position within the same block bordered by major faults. To visualize 3D subsidence maps, the wells were arranged to a set of 3D points based on their map location (x, y) and depths (z1, z2, z3 ...). The division of the stratigraphic column and age range was arranged based on the Central Paratethys regional Stages. In this study, MATLAB, a numerical computing environment, was used to calculate the TPS interpolation function. The Thin-Plate Spline (TPS) can be employed to reconstruct a smooth surface from a set of 3D points. The basic physical model of the TPS is based on the bending behavior of a thin metal sheet that is constrained only by a sparse set of fixed points. In the Lower Miocene, 3D subsidence maps show strong evidence that the pre-Neogene basement of the Vienna Basin was subsiding along borders of the Alpine-Carpathian nappes. This subsidence event is represented by a piggy-back basin developed on top of the NW-ward moving thrust sheets. In the late Lower Miocene, Group C and N display a typical subsidence pattern for the pull-apart basin with a very high subsidence event (0.2 - 1.0 km/Ma). After the event, Group N shows remarkably decreasing subsidence, following the thin-skinned extension which was regarded as the extension model of the Vienna Basin in the literature. But the subsidence in Group C decreases gradually, which demonstrates a trend of increasing thermal subsidence during the Middle to Upper Miocene. The traditional model cannot explain the thermal subsidence observed in the central part. This study supports a non-uniform extension model changing from the thin-skinned extension in the northern part to the thick-skinned extension in the central part. And 3D subsidence maps propose the existence of a decoupling between lithospheric and crustal extensions along the Steinberg Fault. Group L shows very different subsidence trends compared to Group C and N. In this Group a subsidence halt occurred in the late Lower Miocene. After the halt, Group L1 shows small tectonic and subsidence events. Some former studies presented that the area of Group L1 uplifted during the early Middle Miocene. It can be concluded that the missing sediments were eroded by the local uplift. But the subsidence of Group L2 stopped completely. It suggests that Group L2 was not influenced by the extension of the strike-slip fault system.

Deciphering the Influence of Crustal Flexure and Shear Along the Margins of the Eastern Snake River Plain

NASA Astrophysics Data System (ADS)

Parker, S. D.

2016-12-01

The kinematic evolution of the eastern Snake River Plain (ESRP) remains highly contested. A lack of strike-slip faults bounding the ESRP serves as a primary assumption in many leading kinematic models. Recent GPS geodesy has highlighted possible shear zones along the ESRP yet regional strike-slip faults remain unidentified. Oblique movement within dense arrays of high-angle conjugate normal faults, paralleling the ESRP, occur within a discrete zone of 50 km on both margins of the ESRP. These features have long been attributed to progressive crustal flexure and subsidence within the ESRP, but are capable of accommodating the observed strain without necessitating large scale strike-slip faults. Deformation features within an extensive Neogene conglomerate provide field evidence for dextral shear in a transtensional system along the northern margin of the ESRP. Pressure-solution pits and cobble striations provide evidence for a horizontal ENE/WSW maximum principal stress orientation, consistent with the hypothesis of a dextral Centennial shear zone. Fold hinges, erosional surfaces and stratigraphic datums plunging perpendicular into the ESRP have been attributed to crustal flexure and subsidence of the ESRP. Similar Quaternary folds plunge obliquely into the ESRP along its margins where diminishing offset along active normal faults trends into linear volcanic features. In all cases, orientations and distributions of plunging fold structures display a correlation to the terminus of active Basin and Range faults and linear volcanic features of the ESRP. An alternative kinematic model, rooted in kinematic disparities between Basin and Range faults and parallelling volcanic features may explain the observed downwarping as well as provide a mechanism for the observed shear along the margins of the ESRP. By integrating field observations with seismic, geodetic and geomorphic observations this study attempts to decipher the signatures of crustal flexure and shear along the margins of the ESRP. Decoupling the influence of these distinct processes on deformation features bounding the ESRP will aid in our understanding of the kinematic evolution of this highly complex region.

46 CFR 381.8 - Subsidized vessel participation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... from MARAD an amount for the operating-differential subsidy (ODS) likely to be paid for the carriage of... subsidized bidders; (2) Deriving “augmented bids” for the subsidized operators by adding the ODS amount to... on MARAD's calculation of anticipated costs (less ODS in the case of a subsidized vessel) for the...

Texture segmentation by genetic programming.

PubMed

Song, Andy; Ciesielski, Vic

2008-01-01

This paper describes a texture segmentation method using genetic programming (GP), which is one of the most powerful evolutionary computation algorithms. By choosing an appropriate representation texture, classifiers can be evolved without computing texture features. Due to the absence of time-consuming feature extraction, the evolved classifiers enable the development of the proposed texture segmentation algorithm. This GP based method can achieve a segmentation speed that is significantly higher than that of conventional methods. This method does not require a human expert to manually construct models for texture feature extraction. In an analysis of the evolved classifiers, it can be seen that these GP classifiers are not arbitrary. Certain textural regularities are captured by these classifiers to discriminate different textures. GP has been shown in this study as a feasible and a powerful approach for texture classification and segmentation, which are generally considered as complex vision tasks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, L.M.; Clayton, M.; Everingham, J.

A comparison of background and potential geopressured geothermal development-related subsidence rates is given. Estimated potential geopressured-related rates at six prospects are presented. The effect of subsidence on the Texas-Louisiana Gulf Coast is examined including the various associated ground movements and the possible effects of these ground movements on surficial processes. The relationships between ecosystems and subsidence, including the capability of geologic and biologic systems to adapt to subsidence, are analyzed. The actual potential for environmental impact caused by potential geopressured-related subsidence at each of four prospects is addressed. (MHR)

E-Area LLWF Vadose Zone Model: Probabilistic Model for Estimating Subsided-Area Infiltration Rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyer, J.; Flach, G.

A probabilistic model employing a Monte Carlo sampling technique was developed in Python to generate statistical distributions of the upslope-intact-area to subsided-area ratio (Area UAi/Area SAi) for closure cap subsidence scenarios that differ in assumed percent subsidence and the total number of intact plus subsided compartments. The plan is to use this model as a component in the probabilistic system model for the E-Area Performance Assessment (PA), contributing uncertainty in infiltration estimates.

REM Sleep Behavior Disorder: Updated Review of the Core Features, the RBD-Neurodegenerative Disease Association, Evolving Concepts, Controversies, and Future Directions

PubMed Central

Boeve, Bradley F.

2010-01-01

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia manifested by vivid, often frightening dreams associated with simple or complex motor behavior during REM sleep. Patients appear to “act out their dreams,” in which the exhibited behaviors mirror the content of the dreams, and the dream content often involves a chasing or attacking theme. The polysomnographic features of RBD include increased electromyographic tone +/- dream enactment behavior during REM sleep. Management with counseling and pharmacologic measures is usually straight-forward and effective. In this review, the terminology, clinical and polysomnographic features, demographic and epidemiologic features, diagnostic criteria, differential diagnosis, and management strategies are discussed. Recent data on the suspected pathophysiologic mechanisms of RBD are also reviewed. The literature and our institutional experience on RBD are next discussed, with an emphasis on the RBD-neurodegenerative disease association and particularly the RBD-synucleinopathy association. Several issues relating to evolving concepts, controversies, and future directions are then reviewed, with an emphasis on idiopathic RBD representing an early feature of a neurodegenerative disease and particularly an evolving synucleinopathy. Planning for future therapies that impact patients with idiopathic RBD is reviewed in detail. PMID:20146689

Land subsidence near oil and gas fields, Houston, Texas.

USGS Publications Warehouse

Holzer, T.L.; Bluntzer, R.L.

1984-01-01

Subsidence profiles across 29 oil and gas fields in the 12 200 km2 Houston, Texas, regional subsidence area, which is caused by the decline of ground-water level, suggest that the contribution of petroleum withdrawal to local land subsidence is small. In addition to land subsidence, faults with an aggregate length of more than 240 km have offset the land surface in historical time. Natural geologic deformation, ground-water pumping, and petroleum withdrawal have all been considered as potential causes of the historical offset across these faults. The minor amount of localized land subsidence associated with oil and gas fields, suggests that petroleum withdrawal is not a major cause of the historical faulting. -from Authors

An ecological mechanism to create regular patterns of surface dissolution in a low-relief carbonate landscape

NASA Astrophysics Data System (ADS)

Cohen, M. J.; Martin, J. B.; Mclaughlin, D. L.; Osborne, T.; Murray, A.; Watts, A. C.; Watts, D.; Heffernan, J. B.

2012-12-01

Development of karst landscapes is controlled by focused delivery of water undersaturated with respect to the soluble rock minerals. As that water comes to equilibrium with the rock, secondary porosity is incrementally reinforced creating a positive feedback that acts to augment the drainage network and subsequent water delivery. In most self-organizing systems, spatial positive feedbacks create features (in landscapes: patches; in karst aquifers: conduits) whose size-frequency relationship follows a power function, indicating a higher probability of large features than would occur with a random or Gaussian genesis process. Power functions describe several aspects of secondary porosity in the Upper Floridan Aquifer in north Florida. In contrast, a different pattern arises in the karst landscape in southwest Florida (Big Cypress National Preserve; BICY), where low-relief and a shallow aquiclude govern regional hydrology. There, the landscape pattern is highly regular (Fig. 1), with circular cypress-dominated wetlands occupying depressions that are hydrologically isolated and distributed evenly in a matrix of pine uplands. Regular landscape patterning results from spatially coupled feedbacks, one positive operating locally that expands patches coupled to another negative that operates at distance, eventually inhibiting patch expansion. The positive feedback in BICY is thought to derive from the presence of surface depressions, which sustain prolonged inundation in this low-relief setting, and facilitate wetland development that greatly augments dissolution potential of infiltrating water in response to ecosystem metabolic processes. In short, wetlands "drill" into the carbonate leading to both vertical and lateral basin expansion. Wetland expansion occurs at the expense of surrounding upland area, which is the local catchment that subsidizes water availability. A distal inhibitory feedback on basin expansion thus occurs as the water necessary to sustain prolonged inundation becomes limiting. The implied strong reciprocal coupling between surface production of organic matter and patterns of induced subsurface carbonate dissolution are a novel example of co-evolving biogeomorphic processes in the earth system. Fig. 1 - Regular patterned landscape in Big Cypress National Preserve showing cypress dominated wetlands (round features) embedded in a mosaic of pine and grass uplands. Exposed carbonate rings are evident at the margins of many of the wetland basins.

Depressions and other lake-floor morphologic features in deep water, southern Lake Michigan

USGS Publications Warehouse

Colman, Steven M.; Foster, D.S.; Harrison, D.W.

1992-01-01

The most common features are subcircular depressions, commonly compound, that are irregularly distributed across the lake floor. The depressions are most common in the southern basin of the lake where lacustrine sediments are more than a few meters thick, corresponding to water depths greater than about 90 m. We have divided the depressions into three types on the basis of their internal structure seen in seismic-reflection profiles. The depressions show varying degrees of muting, ranging from fresh to completely buried, suggesting a range in the time of their formation. The origin of the depressions is problematic, but their structure suggests collapse and(or) subsidence. -from Authors

Research on the Crustal Deformation Characteristics in Beijing Using Insar and Gnss Technology

NASA Astrophysics Data System (ADS)

Hu, L.; Xing, C.; Dai, K.; Li, Y.; Li, Z.; Zhang, J.; Yan, R.; Xu, B.; Fan, Z.

2018-04-01

In this paper, we tried to reveal the characteristics of the crustal deformation in both the horizontal and vertical directions in Beijing using InSAR and GNSS observations. Regarding the serious land subsidence in Beijing plain, we also analysed the mechanism of the occurrence and development of the subsidence in combination with the tectonic settings. The GNSS results reveal that the crust in Beijing shows a significant left-lateral trend movement in the horizontal direction, while the vertical direction shows a gentle rise in the mountainous region and a significant subsidence in the plain area. The INSAR results shows a detailed subsidence area and the deformation characteristics were analyzed considering the fault activity. The foundation of geological structure dominates the subsiding in the Beijing Plain. The exploitation of groundwater exacerbates the level of subsidence and has new development. The active faults controlled the development of the subsiding in present days.

Rapid subsidence over oil fields measured by SAR

NASA Technical Reports Server (NTRS)

Fielding, E. J.; Blom, R. G.; Goldstein, R. M.

1998-01-01

The Lost Hills and Belridge oil felds are in the San Joaquin Valley, California. The major oil reservoir is high porosity and low permeability diatomite. Extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction, forming a surface subsidence bowl. We measure this subsidence from space using interferometric analysis of SAR (Synthetic Aperture Radar) data collected by the European Space Agency Remote Sensing Satellites (ERS-1 and ERS-2). Maximum subsidence rates are as high as 40 mm in 35 days or > 400 mm/yr, measured from interferograms with time separations ranging from one day to 26 months. The 8- and 26-month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ERS SAR, but shows increased detail in areas of less rapid subsidence. Synoptic mapping of subsidence distribution from satellite data powerfully complements ground-based techniques, permits measurements where access is difficult, and aids identification of underlying causes.

Research the Mechanism of Land Subsidence in Typical Area, Beijing

NASA Astrophysics Data System (ADS)

Liu, H.; Zhang, Y.; Wang, R.; Gu, Z.

2014-12-01

In recently years, the subsidence develop rapidly in Beijing. It can not be ignored the influence of the security of major project. Beijing Singapore city is located at the junction of Daxing and Hebei. The per captia water resources is 190m3.,far below the internationally safety limit 1000m3. The region is the dryland water resource and continued extraction groundwater caused land subsidence issue become increasingly prominent. With the Beijing Singapore city put into use, the amount of water shortages must further seriously and land subsidence subsidence area must be further increased. Therefore, monitor the land subsidence of Beijing Singapore city area and research its settlement mechanism, it is so important to ensure the safe operation of Beijing Singapore city . Explore the soil and water coupling mechanism of Beijing Singapore citya during land subsidence process, and optimize groundwater extraction program to ensure the safe operation of Beijing's second largest airport.

Family Home Childcare Providers: A Comparison of Subsidized and Non-Subsidized Working Environments and Employee Issues

ERIC Educational Resources Information Center

Shriner, Michael; Schlee, Bethanne M.; Mullis, Ronald L.; Cornille, Thomas A.; Mullis, Ann K.

2008-01-01

Federal and State Governments provide childcare subsidies for low-income working families. This study compares the encountered issues and working environments of family home providers of subsidized and non-subsidized childcare. Questionnaires were distributed throughout a southeastern state in the United States to 548 family home childcare…

Land subsidence associated with hydrocarbon production, Texas Gulf Coast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreitler, C.W.; White, W.A.; Akhter, M.S.

1988-01-01

Although ground-water withdrawal has been the predominant cause of land subsidence in the Texas Gulf Coast, localized subsidence and faulting have also resulted from hydrocarbon production. Subsidence was documented as early as the 1920s over the Goose Creek field. Since then, subsidence and/or faulting have been identified over the Saxet, South Houston, Chocolate Bayou, Hastings, Alco-Mag, Clinton, Mykawa, Blue Ridge, Webster, and Caplen oil fields. Oil-production-related subsidence over these fields generally creates few environmental or engineering problems. One exception is the subsidence and faulting over the Caplen oil field on Bolivar Peninsula, where more than 1,000 ac of saltwater marshmore » has been replaced by subaqueous flats. Subsidence may be occurring over other fields but has not been identified because of limited releveled benchmark data. An evaluation of drill-stem and bottom-hole pressure data for the Frio Formation in Texas indicates extensive depressurization presumably from hydrocarbon production. Nearly 12,000 measurements from a pressure data base of 17,000 measurements indicate some depressurization. Some of the Frio zones have pressure declines of more than 1,500 psi from original hydrostatic conditions. Subsidence and faulting may be associated with these fields in the Frio as well as other Tertiary formations where extensive hydrocarbon production and subsequent depressurization have occurred.« less

Review: Water-rock interactions and related eco-environmental effects in typical land subsidence zones of China

NASA Astrophysics Data System (ADS)

Ma, Teng; Du, Yao; Ma, Rui; Xiao, Cong; Liu, Yanjun

2018-01-01

Land subsidence is common in some regions of China. Various eco-environmental problems have arisen due to changes in water-rock interactions in these subsided areas, for which a comprehensive understanding of the hydrogeological setting is needed. This paper presents the general status of land subsidence in three typical subsided areas of China through the compilation of relevant data, and reviews some typical changes in the water-rock interactions in subsided areas along with related eco-environmental issues. It is found that the subsidence development and distribution are controlled by the groundwater-withdrawal intensity externally, and by the thickness and compressibility of unconsolidated sediments internally. The physical changes and related effects of water-rock interactions in subsided areas include: (1) the decreased ground elevation that caused floods, waterlogged farmland, etc.; (2) the differential subsidence that caused ground fissures; and (3) the change of seepage field that caused substantial reduction of the water resource. Chemically, the changes and related effects of water-rock interactions include: (1) the change to the chemical environment or processes due to the hydrogeologic structure alteration, which caused groundwater pollution; and (2) hydrologic mixing (seawater intrusion, artificial recharge; exchange with adjacent aquifers or aquitards), which degraded the groundwater quality. Further research on the subsided areas in China is suggested to reveal the mechanisms regarding biological and gaseous (meteorological) changes from the perspective of interacting systems among water, rocks, biological agents and gases.

Subsidence in the Central Valley, California 2007 - present measured by InSAR

NASA Astrophysics Data System (ADS)

Farr, T. G.; Liu, Z.; Jones, C. E.

2015-12-01

Subsidence caused by groundwater pumping in the rich agricultural area of California's Central Valley has been a problem for decades. Over the last few years, interferometric synthetic aperture radar (InSAR) observations from satellite and aircraft platforms have been used to produce maps of subsidence with ~cm accuracy. For this study, we have obtained and analyzed Japanese PALSAR data for 2006 - 2011, Canadian Radarsat-1 data for 2011 - 2013, Radarsat-2 data for 2012 - 2015, and ESA's Sentinel-1A for 2015 and produced maps of subsidence for those periods. High resolution InSAR data were also acquired along the California Aqueduct by the NASA UAVSAR from 2013 - 2015. Using multiple scenes acquired by these systems, we were able to produce the time histories of subsidence at selected locations and transects showing how subsidence varies both spatially and temporally. The maps show that subsidence is continuing in areas with a history of subsidence and that the rates and areas affected have increased due to increased groundwater extraction during the extended western US drought. The high resolution maps from UAVSAR were used to identify and quantify new, highly localized areas of accelerated subsidence along the California Aqueduct that occurred in 2014. The California Department of Water Resources (DWR) funded this work to provide the background and an update on subsidence in the Central Valley to support future policy. Geographic Information System (GIS) files are being furnished to DWR for further analysis of the 4 dimensional subsidence time-series maps. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

Preliminary subsidence investigation of Sacramento Valley, California

USGS Publications Warehouse

Lofgren, B.E.; Ireland, R.L.

1973-01-01

Although a number of agencies have made leveling surveys in Sacramento Valley and a valleywide network of first- and second-order control exists, few areas have sufficient control for determining whether land subsidence has occurred and if so, how much, within the time span of vertical control. Available data suggest that 0.2 to 0.9 foot (0.06 to 0.3 m) of subsidence probably has occurred from 1935-42 to 1964 in an extensive agricultural area of heavy ground-water pumping between Zamora and Davis, and that as much as 2 feet (0.6 m) of subsidence has occurred in at least two areas of pumping overdraft--east of Zamora, and west of Arbuckle. A comparison of maps showing long-term water-level decline and average annual ground-water pumpage indicates several other areas of probable subsidence. In six general areas--northwest of Sacramento; northeast of Sacramento; southeast of Yuba City; 10 miles (16 km) north of Willows; 20 miles (32 km) north of Willows; and especially in the Arbuckle area,ground-water declines have quite probably produced significant subsidence. In two areas of most intensive pumping, no long-term water-level declines have occurred, and no subsidence is indicated. If problems of land subsidence are of concern in Sacramento Valley, and if estimates of historic subsidence or subsidence potential are needed, serious consideration should be given to a field program of basic-data collection. Second-order leveling along a few carefully selected lines of existing control, and the installation and operation of two or three compaction recorders in areas of continuing water-level decline, would provide helpful data for estimating .past and future subsidence.

[The impact of load density differences on land subsidence based on build-up index and PS-InSAR technology].

PubMed

Chen, Bei-Bei; Gong, Hui-Li; Li, Xiao-Juan; Lei, Kun-Chao; Lin, Zhu; Wang, Yan-Bing

2013-08-01

The excessive mining for underground water is the main reason inducing the land subsidence in Beijing, while, increasing of load brought by the urban construction aggravate the local land subsidence in a certain degree. As an international metropolis, the problems of land subsidence that caused by urban construction are becoming increasingly highlights, so revealing the relationship between regional load increase and the response of land subsidence also becomes one of the key problems in the land subsidence research field. In order to analyze the relationship between the load changes in construction and the land subsidence quantitatively, the present study selected the TM remote sensing image covering Beijing plain and used Erdas Modeler tool to invert the index based on building site (IBI), acquired the spatial and temporal change information in research area further; Based on results monitored by PS-InSAR (permanent scatterer interferometry) and IBI index method, and combined with the GIS spatial analysis method in the view of pixels in different scales, this paper analyzes the correlation between typical area load change and land subsidence, The conclusions show that there is a positive correlation between the density of load and the homogeneity of subsidence, especially in area which has a high sedimentation rate. Owing to such characteristics as the complexity and hysteretic nature of soil and geological structure, it is not obvious that the land subsidence caused by the increase of load in a short period. But with the increasing of local land load made by high density buildings and additional settlement of each monomer building superposed with each other, regional land subsidence is still a question that cannot be ignored and needs long-term systematic research and discussion.

Relationship between subsidence and volcanic load, Hawaii

USGS Publications Warehouse

Moore, J.G.

1970-01-01

A computer analysis of tide-gage records in the northeast Pacific indicates that the active volcanic islands of eastern Hawaii are subsiding at a rate considerably faster than the eustatic rise of sea level. The rate of absolute subsidence increases progressively toward the center of current activity on the Island of Hawaii. Honolulu, Oahu, appears to be stable; Kahului, Maui, is subsiding at 1.7 mm per year; and Hilo, Hawaii, is subsiding at 4.8 mm per year. This subsidence is apparently related to downbowing of the crust throughout a zone 400 km in diameter by the weight of volcanic material added to the crust by active volcanoes, principally Mauna Loa and Kilauea on the Island of Hawaii. The Hawaiian Arch encircles the subsiding zone and may be uplifted by material moving down and outward from the zone of subsidence. The annual volume of subsidence is about 270??106 m3, whereas the average annual volume of erupted basalt on the Island of Hawaii (based on historic records back to about 1820) is about 50??106 m3. The great excess of subsidence over volcanic addition cannot be reconciled by isostatic models, and is apparently the result of other processes operating in the volcano and its basement thet are poorly understood. Probably the more important of these processes are intrusions and submarine volcanism, both of which are providing additional unseen load on the volcanoes. Furthermore, the rate of eruption may be uplifted by material moving down and outward from the zone of subsidence may be overestimated due to localized downslope movement of the margins of the islands. ?? 1970 Stabilimento Tipografico Francesco Giannini & Figli.

Steady subsidence of Medicine Lake volcano, northern California, revealed by repeated leveling surveys

USGS Publications Warehouse

Dzurisin, D.; Poland, Michael P.; Burgmann, R.

2002-01-01

Leveling surveys of a 193-km circuit across Medicine Lake volcano (MLV) in 1954 and 1989 show that the summit area subsided by as much as 302 ?? 30 mm (-8.6 ?? 0.9 mm/yr) with respect to a datum point near Bartle, California, 40 km to the southwest. This result corrects an error in the earlier analysis of the same data by Dzurisin et al. [1991], who reported the subsidence rate as -11.1 ?? 1.2 mm/yr. The subsidence pattern extends across the entire volcano, with a surface area of nearly 2000 km2. Two areas of localized subsidence by as much as 20 cm can be attributed to shallow normal faulting near the volcano's periphery. Surveys of an east-west traverse across Lava Beds National Monument on the north flank of the volcano in 1990 and of a 23-km traverse across the summit area in 1999 show that subsidence continued at essentially the same rate during 1989-1999 as 1954-1989. Volcano-wide subsidence can be explained by either a point source of volume loss (Mogi) or a contracting horizontal rectangular dislocation (sill) at a depth of 10-11 km. Volume loss rate estimates range from 0.0013 to 0.0032 km3/yr, depending mostly on the source depth estimate and source type. Based on first-order quantitative considerations, we can rule out that the observed subsidence is due to volume loss from magma withdrawal, thermal contraction, or crystallizing magma at depth. Instead, we attribute the subsidence and faulting to: (1 gravitational loading of thermally weakened crust by the mass of the volcano and associated intrusive rocks, and (2) thinning of locally weakened crust by Basin and Range deformation. The measured subsidence rate exceeds long-term estimates from drill hole data, suggesting that over long timescales, steady subsidence and episodic uplift caused by magmatic intrusions counteract each other to produce the lower net subsidence rate.

Sinking Coastal Cities

NASA Astrophysics Data System (ADS)

Erkens, G.; Stuurman, R.; De Lange, G.; Bucx, T.; Lambert, J.

2014-12-01

In many coastal cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will continue to sink, even below sea level. The ever increasing industrial and domestic demand for water in these cities results in excessive groundwater extraction, causing severe subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick sequences of soft soil. The impacts of subsidence are further exacerbated by climate-induced sea level rise. Land subsidence results in two types damage: foremost it increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. Secondly, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs of roads and transportation networks, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annually. To survey the extent of groundwater associated subsidence, we conducted a quick-assessment of subsidence in a series of mega-cities (Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok). For each city research questions included: what are the main causes, how much is the current subsidence rate and what are predictions, where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and what governmental bodies are involved and responsible to act? Using the assessment, this paper discusses subsidence modelling and measurement results from the selected cities. The focus is on the importance of delayed settlement after increases in hydraulic heads, the role of the subsurface composition for subsidence rates and best practice solutions for subsiding cities. For the latter, urban (ground)water management, adaptive flood risk management and related spatial planning strategies are just examples of the options available. The discussions in this paper form the building blocks for a much-needed research agenda that aims to deliver a strategy to deal with subsidence in current and future subsidence-prone areas.

Magnitude and extent of land subsidence in central Mexico revealed by regional InSAR ALOS time-series survey

NASA Astrophysics Data System (ADS)

Chaussard, E.; Wdowinski, S.; Amelung, F.; Cabral-Cano, E.

2013-05-01

Massive groundwater extraction is very common in Mexico and is well known to result in land subsidence. However, most surveys dedicated to land subsidence focus on one single city, mainly Mexico City, and thus fail to provide a comprehensive picture of the problem. Here we use a space-based radar remote sensing technique, known as Interferometric Synthetic Aperture Radar (InSAR) to detect land subsidence in the entire central Mexico area. We used data from the Japanese satellite ALOS, processed over 600 SAR images acquired between 2007-2011 and produced over 3000 interferograms to cover and area of 200,000 km2 in central Mexico. We identify land subsidence in twenty-one areas, including seventeen cities, namely from east to west, Puebla, Mexico city, Toluca de Lerdo, Queretaro, San Luis de la Paz, south of San Luis de la Paz, Celaya, south of Villa de Reyes, San Luis Potosi, west of Villa de Arista, Morelia, Salamanca, Irapuato, Silao, Leon, Aguascalientes, north of Aguascalientes, Zamora de Hidalgo, Guadalajara, Ahuacatlan, and Tepic. Subsidence rates of 30 cm/yr are observed in Mexico City, while in the other locations typical rates of 5-10 cm/yr are noticed. Regional surveys of this type are necessary for the development of hazard mitigation plans and efficient use of ground-based monitoring. We additionally correlate subsidence with land use, surface geology, and faults distribution and suggest that groundwater extraction for agricultural, urban, and industrial uses are the main causes of land subsidence. We also reveal that the limits of the subsiding areas often correlate with existing faults, motion on these faults being driven by water extraction rather than by tectonic activity. In all the subsiding locations we observe high ground velocity gradients emphasizing the significant risks associated with land subsidence in central Mexico. Averaged 2007-2011 ground velocity map from ALOS InSAR time-series in central Mexico, revealing land subsidence in 21 locations. The color scale shows red colors as subsidence and blue colors as uplift. The emplacement of subsiding cities are shown by black diamonds and labeled for reference, the ones included in the UNESCO World Heritage list are shown with an asterisk.

Lapatinib-induced acute generalized exanthematous pustulosis

PubMed Central

Lakshmi, Chembolli; Pillai, Suma; Srinivas, C. R.

2010-01-01

Acute generalized exanthematous pustulosis (AGEP) is a pustular eruption, mainly drug induced often accompanied by fever and neutrophilic leukocytosis presenting as scarlatiniform erythema over the flexures evolving into numerous tiny non follicular pustules. We present a case report of a 56-year old woman, who had undergone mastectomy, treated with lapatinib for metastatic disease, and who presented with multiple erythematous papules and plaques with peripheral pustules. She also developed painful pyogenic granuloma-like lesions over the pulp of toe and over the proximal nail folds.All the lesions subsided following withdrawal of lapatinib. Although AGEP has been reported with imatinib (a multikinase inhibitor), there have been no reports of serious reactions with lapatinib, an EGFR inhibitor. This case could represent the first case report of AGEP to the EGFR inhibitor, lapatinib. PMID:23130185

Improving Naive Bayes with Online Feature Selection for Quick Adaptation to Evolving Feature Usefulness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pon, R K; Cardenas, A F; Buttler, D J

The definition of what makes an article interesting varies from user to user and continually evolves even for a single user. As a result, for news recommendation systems, useless document features can not be determined a priori and all features are usually considered for interestingness classification. Consequently, the presence of currently useless features degrades classification performance [1], particularly over the initial set of news articles being classified. The initial set of document is critical for a user when considering which particular news recommendation system to adopt. To address these problems, we introduce an improved version of the naive Bayes classifiermore » with online feature selection. We use correlation to determine the utility of each feature and take advantage of the conditional independence assumption used by naive Bayes for online feature selection and classification. The augmented naive Bayes classifier performs 28% better than the traditional naive Bayes classifier in recommending news articles from the Yahoo! RSS feeds.« less

Analysis of Land Subsidence Monitoring in Mining Area with Time-Series Insar Technology

NASA Astrophysics Data System (ADS)

Sun, N.; Wang, Y. J.

2018-04-01

Time-series InSAR technology has become a popular land subsidence monitoring method in recent years, because of its advantages such as high accuracy, wide area, low expenditure, intensive monitoring points and free from accessibility restrictions. In this paper, we applied two kinds of satellite data, ALOS PALSAR and RADARSAT-2, to get the subsidence monitoring results of the study area in two time periods by time-series InSAR technology. By analyzing the deformation range, rate and amount, the time-series analysis of land subsidence in mining area was realized. The results show that InSAR technology could be used to monitor land subsidence in large area and meet the demand of subsidence monitoring in mining area.

Surface Deformation in Quetta Valley, Balochistan, Pakistan

NASA Astrophysics Data System (ADS)

Huang, J.; Shuhab, K.; Wulamu, A.; Crupa, W.; Khan, A. S.; Kakar, D. M.; Kasi, A.

2015-12-01

In February 2011, several ground fissures up to ~1.8 km in length appeared in the Quetta Valley, Balochsitan, Pakistan. It is not clear what caused the sudden occurrence of these fissures. The region is tectonically active and bounded to the west by several regional strike-slip faults including the north-south striking left-lateral Chaman fault system that slips at ~10 mm per year. Several large earthquakes have occurred recently in this area, one fatal 6.4 magnitude (Mw) earthquake occurred on October 28th, 2008. Some parts of Quetta Valley are subsiding; GPS data from two stations in Quetta that span mid-2006 - 2009 recorded subsidence rates of ~10 cm per year. Although subsidence in urban areas is generally attributed to groundwater depletion, it is not clear whether ground fissures are caused by water withdrawal or related to tectonics of the region. This study is designed to quantify and assess the source of surface deformation in Quetta Valley using InSAR, GPS, seismic and earthquake centroid moment tensor data. To detect and map the spatial-temporal features of the processes that led to the surface deformation, we used two time series, i.e., 15 European Remote Sensing (ERS-1/2) satellite images from 1992 - 1999 and 27 ENVISAT images spanning 2003 - 2010. A Differential Interferometric Synthetic Aperture Radar (DInSAR) Small Baseline Subset (SBAS) technique was used to investigate surface deformation. Eleven continuous-GPS stations within the InSAR antenna footprint were compared with the InSAR time series for quality control. Preliminary InSAR results revealed that the areas in and around the fissures are subsiding at 5 cm per year. Five seismic lines totaling ~60 km, acquired in 2003, were used to interpret faults beneath Holocene alluvium in the Quetta Valley. One of the blind faults is a north-south striking thrust fault mapped north into the Takatu range. However, a focal mechanism for the 2008 earthquake in this region indicated northwest-southeast strike-slip fault movement.

Recharge from a subsidence crater at the Nevada test site

USGS Publications Warehouse

Wilson, G. V.; Ely, D.M.; Hokett, S. L.; Gillespie, D. R.

2000-01-01

Current recharge through the alluvial fans of the Nevada Test Site (NTS) is considered to be negligible, but the impact of more than 400 nuclear subsidence craters on recharge is uncertain. Many of the craters contain a playa region, but the impact of these playas has not been addressed. It was hypothesized that a crater playa would focus infiltration through the surrounding coarser-grained material, thereby increasing recharge. Crater U5a was selected because it represented a worst case for runoff into craters. A borehole was instrumented for neutron logging beneath the playa center and immediately outside the crater. Physical and hydraulic properties were measured along a transect in the crater and outside the crater. Particle-size analysis of the 14.6 m of sediment in the crater and morphological features of the crater suggest that a large ponding event of ≈63000 m3 had occurred since crater formation. Water flow simulations with HYDRUS-2D, which were corroborated by the measured water contents, suggest that the wetting front advanced initially by as much as 30 m yr−1 with a recharge rate 32 yr after the event of 2.5 m yr−1Simulations based on the measured properties of the sediments suggest that infiltration will occur preferentially around the playa perimeter. However, these sediments were shown to effectively restrict future recharge by storing water until removal by evapotranspiration (ET). This work demonstrated that subsidence craters may be self-healing.

Preliminary assessment of a Cretaceous-Paleogene Atlantic passive margin, Serrania del Interior and Central Ranges, Venezuela/Trinidad

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pindell, J.L.; Drake, C.L.; Pitman, W.C.

1991-03-01

For several decades, Cretaceous arc collision was assumed along northern Venezuela based on isotopic ages of metamorphic minerals. From subsidence histories in Venezuelan/Trinidadian basins, however, it is now clear that the Cretaceous metamorphic rocks were emplaced southeastward as allochthons above an autochthonous suite of rocks in the Cenozoic, and that the pre-Cenozoic autochthonous rocks represent a Mesozoic passive margin. The passive margin rocks have been metamorphosed separately during overthrusting by the allochthons in central Venezuela, but they are uplifted but not significantly metamorphosed in Eastern Venezuela and Trinidad. There, in the Serrania del Interior and Central Ranges of Venezuela/Trinidad, Mesozoic-Paleogenemore » passive margin sequences were uplifted in Neogene time, when the Caribbean Plate arrived from the west and transpressionally inverted the passive margin. Thus, this portion of South America's Atlantic margin subsided thermally without tectonism from Jurassic to Eocene time, and these sections comprise the only Mesozoic-Cenozoic truly passive Atlantic margin in the Western Hemisphere that is now exposed for direct study. Direct assessments of sedimentological, depositional and faunal features indicative of, and changes in, water depth for Cretaceous and Paleogene time may be made here relative to a thermally subsiding passive margin without the complications of tectonism. Work is underway, and preliminary assessments presented here suggest that sea level changes of Cretaceous-Paleogene time are not as pronounced as the frequent large and rapid sea level falls and rises that are promoted by some.« less

Facies architecture of a Triassic rift-related Silicic Volcano-Sedimentary succession in the Tethyan realm, Peonias subzone, Vardar (Axios) Zone, northern Greece; Regional implications

NASA Astrophysics Data System (ADS)

Asvesta, Argyro; Dimitriadis, Sarantis

2010-06-01

In northern Greece, along the western edge of the Paleozoic Vertiscos terrane (Serbomacedonian massif) and within the Peonias subzone - the eastern part of the Vardar (Axios) Zone - a Silicic Volcano-Sedimentary (SVS) succession of Permo(?)-Skythian to Mid Triassic age records the development of a faulted continental margin and the formation of rhyolitic volcanoes along a continental shelf fringed by neritic carbonate accumulations. It represents the early rifting extensional stages that eventually led to the opening of the main oceanic basin in the western part of the Vardar (Axios) Zone (the Almopias Oceanic Basin). Even though the SVS succession is deformed, altered, extensively silicified and metamorphosed in the low greenschist facies, primary textures, original contacts and facies relationships are recognized in some places allowing clues for the facies architecture and the depositional environment. Volcanic and sedimentary facies analysis has been carried out at Nea Santa and Kolchida rhyolitic volcanic centres. Pyroclastic facies, mostly composed of gas-supported lapilli tuffs and locally intercalated accretionary lapilli tuffs, built the early cones which were then overridden by rhyolitic aphyric and minor K-feldspar-phyric lava flows. The characteristics of facies, especially the presence of accretionary lapilli, imply subaerial to coastal emplacement at this early stage. The mature and final stages of volcanism are mostly represented by quartz-feldspar porphyry intrusions that probably occupied the vents. At Nea Santa area, the presence of resedimented hyaloclastite facies indicates subaqueous emplacement of rhyolitic lavas and/or lobes. Moreover, quartz-feldspar-phyric sills and a partly extrusive dome featuring peperites at their margins are inferred to have intruded unconsolidated, wet carbonate sediments of the overlying Triassic Neritic Carbonate Formation, in a shallow submarine environment. The dome had probably reached above wave-base as is indicated by the presence of reworked rhyolitic clasts in the younger mixed rhyolite-carbonate epiclastic sedimentary facies. This facies is interpreted as mass- and debris-flow of mixed provenance, deposited below wave-base. The facies architecture of the SVS succession records a change in volcanic activity from explosive to effusive and then to intrusive. The depositional environment changed from subaerial-coastal to shallow submarine as the silicic volcanism evolved and carbonate sedimentation was progressively taking over, probably compensating for the gradual subsidence of the corresponding basin. Silicic magmatism and carbonate sedimentation were contemporaneous and spatially related. The timing of the rifting, the continental crustal elements involved and the accompanying tectonic, magmatic and sedimentary processes are features of the spatially and temporally evolving western peri-Tethyan region.

Evidence of regional subsidence and associated interior wetland loss induced by hydrocarbon production, Gulf Coast region, USA

USGS Publications Warehouse

Morton, R.A.; Bernier, J.C.; Barras, J.A.

2006-01-01

Analysis of remote images, elevation surveys, stratigraphic cross-sections, and hydrocarbon production data demonstrates that extensive areas of wetland loss in the northern Gulf Coast region of the United States were associated with large-volume fluid production from mature petroleum fields. Interior wetland losses at many sites in coastal Louisiana and Texas are attributed largely to accelerated land subsidence and fault reactivation induced by decreased reservoir pressures as a result of rapid or prolonged extraction of gas, oil, and associated brines. Evidence that moderately-deep hydrocarbon production has induced land-surface subsidence and reactivated faults that intersect the surface include: (1) close temporal and spatial correlation of fluid production with surficial changes including rapid subsidence of wetland sediments near producing fields, (2) measurable offsets of shallow strata across the zones of wetland loss, (3) large reductions in subsurface pressures where subsidence rates are high, (4) coincidence of orientation and direction of displacement between surface fault traces and faults that bound the reservoirs, and (5) accelerated subsidence rates near producing fields compared to subsidence rates in surrounding areas or compared to geological rates of subsidence. Based on historical trends, subsidence rates in the Gulf Coast region near producing fields most likely will decrease in the future because most petroleum fields are nearly depleted. Alternatively, continued extraction of conventional energy resources as well as potential production of alternative energy resources (geopressured-geothermal fluids) in the Gulf Coast region could increase subsidence and land losses and also contribute to inundation of areas of higher elevation. ?? Springer-Verlag 2006.

Groundwater-pumping optimization for land-subsidence control in Beijing plain, China

NASA Astrophysics Data System (ADS)

Qin, Huanhuan; Andrews, Charles B.; Tian, Fang; Cao, Guoliang; Luo, Yong; Liu, Jiurong; Zheng, Chunmiao

2018-01-01

Beijing, in the North China plain, is one of the few megacities that uses groundwater as its main source of water supply. Groundwater accounts for about two-thirds of the city's water supply, and during the past 50 years the storage depletion from the unconsolidated aquifers underlying the city has been >10.4 billion m3. By 2010, groundwater pumping in the city had resulted in a cumulative subsidence of greater than 100 mm in an area of about 3,900 km2, with a maximum cumulative subsidence of >1,200 mm. This subsidence has caused significant social and economic losses in Beijing, including significant damage to underground utilities. This study was undertaken to evaluate various future pumping scenarios to assist in selecting an optimal pumping scenario to minimize overall subsidence, meet the requirements of the Beijing Land Subsidence Prevention Plan (BLSPP 2013-2020), and be consistent with continued sustainable economic development. A numerical groundwater and land-subsidence model was developed for the aquifer system of the Beijing plain to evaluate land subsidence rates under the possible future pumping scenarios. The optimal pumping scenario consistent with the evaluation constraints is a reduction in groundwater pumping from three major pumping centers by 100, 50 and 20%, respectively, while maintaining an annual pumping rate of 1.9 billion m3. This scenario's land-subsidence rates satisfy the BLSPP 2013-2020 and the pumping scenario is consistent with continued economic development. It is recommended that this pumping scenario be adopted for future land-subsidence management in Beijing.

Groundwater-pumping optimization for land-subsidence control in Beijing plain, China

NASA Astrophysics Data System (ADS)

Qin, Huanhuan; Andrews, Charles B.; Tian, Fang; Cao, Guoliang; Luo, Yong; Liu, Jiurong; Zheng, Chunmiao

2018-06-01

Beijing, in the North China plain, is one of the few megacities that uses groundwater as its main source of water supply. Groundwater accounts for about two-thirds of the city's water supply, and during the past 50 years the storage depletion from the unconsolidated aquifers underlying the city has been >10.4 billion m3. By 2010, groundwater pumping in the city had resulted in a cumulative subsidence of greater than 100 mm in an area of about 3,900 km2, with a maximum cumulative subsidence of >1,200 mm. This subsidence has caused significant social and economic losses in Beijing, including significant damage to underground utilities. This study was undertaken to evaluate various future pumping scenarios to assist in selecting an optimal pumping scenario to minimize overall subsidence, meet the requirements of the Beijing Land Subsidence Prevention Plan (BLSPP 2013-2020), and be consistent with continued sustainable economic development. A numerical groundwater and land-subsidence model was developed for the aquifer system of the Beijing plain to evaluate land subsidence rates under the possible future pumping scenarios. The optimal pumping scenario consistent with the evaluation constraints is a reduction in groundwater pumping from three major pumping centers by 100, 50 and 20%, respectively, while maintaining an annual pumping rate of 1.9 billion m3. This scenario's land-subsidence rates satisfy the BLSPP 2013-2020 and the pumping scenario is consistent with continued economic development. It is recommended that this pumping scenario be adopted for future land-subsidence management in Beijing.

Inverse modeling using PS-InSAR for improved calibration of hydraulic parameters and prediction of future subsidence for Las Vegas Valley, USA

NASA Astrophysics Data System (ADS)

Burbey, T. J.; Zhang, M.

2015-11-01

Las Vegas Valley has had a long history of surface deformation due to groundwater pumping that began in the early 20th century. After nearly 80 years of pumping, PS-InSAR interferograms have revealed detailed and complex spatial patterns of subsidence in the Las Vegas Valley area that do not coincide with major pumping regions. High spatial and temporal resolution subsidence observations from InSAR and hydraulic head data were used to inversely calibrate transmissivities (T), elastic and inelastic skeletal storage coefficients (Ske and Skv) of the developed-zone aquifer and conductance (CR) of the basin-fill faults for the entire Las Vegas basin. The results indicate that the subsidence observations from PS-InSAR are extremely beneficial for accurately quantifying hydraulic parameters, and the model calibration results are far more accurate than when using only water-levels as observations, and just a few random subsidence observations. Future predictions of land subsidence to year 2030 were made on the basis of existing pumping patterns and rates. Simulation results suggests that subsidence will continue in northwest subsidence bowl area, which is expected to undergo an additional 11.3 cm of subsidence. Even mitigation measures that include artificial recharge and reduced pumping do not significantly reduce the compaction in the northwest subsidence bowl. This is due to the slow draining of thick confining units in the region. However, a small amount of uplift of 0.4 cm is expected in the North and Central bowl areas over the next 20 years.

Monitoring of land subsidence and ground fissures in Xian, China 2005-2006: Mapped by sar Interferometry

USGS Publications Warehouse

Zhao, C.Y.; Zhang, Q.; Ding, X.-L.; Lu, Z.; Yang, C.S.; Qi, X.M.

2009-01-01

The City of Xian, China, has been experiencing significant land subsidence and ground fissure activities since 1960s, which have brought various severe geohazards including damages to buildings, bridges and other facilities. Monitoring of land subsidence and ground fissure activities can provide useful information for assessing the extent of, and mitigating such geohazards. In order to achieve robust Synthetic Aperture Radar Interferometry (InSAR) results, six interferometric pairs of Envisat ASAR data covering 2005–2006 are collected to analyze the InSAR processing errors firstly, such as temporal and spatial decorrelation error, external DEM error, atmospheric error and unwrapping error. Then the annual subsidence rate during 2005–2006 is calculated by weighted averaging two pairs of D-InSAR results with similar time spanning. Lastly, GPS measurements are applied to calibrate the InSAR results and centimeter precision is achieved. As for the ground fissure monitoring, five InSAR cross-sections are designed to demonstrate the relative subsidence difference across ground fissures. In conclusion, the final InSAR subsidence map during 2005–2006 shows four large subsidence zones in Xian hi-tech zones in western, eastern and southern suburbs of Xian City, among which two subsidence cones are newly detected and two ground fissures are deduced to be extended westward in Yuhuazhai subsidence cone. This study shows that the land subsidence and ground fissures are highly correlated spatially and temporally and both are correlated with hi-tech zone construction in Xian during the year of 2005–2006.

Sinking coastal cities

NASA Astrophysics Data System (ADS)

Erkens, G.; Bucx, T.; Dam, R.; de Lange, G.; Lambert, J.

2015-11-01

In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. A major cause for severe land subsidence is excessive groundwater extraction related to rapid urbanization and population growth. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs for (infra)structure. The total damage worldwide is estimated at billions of dollars annually. As subsidence is often spatially variable and can be caused by multiple processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes? What is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues)? Where are the vulnerable areas? What are the impacts and risks? How can adverse impacts be mitigated or compensated for? Who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

Land Subsidence Monitoring by InSAR Time Series Technique Derived From ALOS-2 PALSAR-2 over Surabaya City, Indonesia

NASA Astrophysics Data System (ADS)

Aditiya, A.; Takeuchi, W.; Aoki, Y.

2017-12-01

Surabaya is the second largest city in Indonesia and the capital of East Java Province with rapid population and industrialization. The impact of urbanization in the big city can suffer potential disasters either nature or anthropogenic such as land subsidence and flood. The pattern of land subsidence need to be mapped for the purposes of planning and structuring the city as well as taking appropriate policy in anticipating and mitigating the impact. This research has used interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique and applied time series analysis to investigate land subsidence occured. The technique includes the process of focusing the SAR data, incorporating the precise orbit, generating interferogram and phase unwrapping using SNAPHU algorithms. The results showed land subsidence has been detected during 2014-2017 over Surabaya city area using ALOS-2/PALSAR-2 images data. These results reveal the subsidence has observed in several area in Surabaya in particular northern part reach up to ∼2 cm/year. The fastest subsidence occurs in highly populated areas suffer vulnerable to flooding and sea level rise impact. In urban areas we found a correlation between land subsidence with residential or industrial land use. It concludes that land subsidence is mainly caused by ground water consumption for industrial and residential use respectively.

Sinkhole-type subsidence over abandoned coal mines in St. David, Illinois. Mine subsidence report, St. David, Illinois. A field survey and analysis of mine subsidence of abandoned coal mines in St. David, Illinois

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wildanger, E.G.; Mahar, J.; Nieto, A.

1980-01-01

This study examined the geologic data, mining history, and subsidence trends of the St. David region. Mine subsidence has occurred due to collapse of the abandoned mine workings. The known subsidence areas have been mapped and described. Results of the study include: (1) St. David has been undermined by both large shipping mines and smaller local mines; (2) sinkholes will continue to develop in this area in response to rock failure and roof collapse above the abandoned mine workings; (3) some primary factors that contribute to the sinkhole problems are the undermining and roof rock composition; (4) sinkholes will bemore » smaller in the future; (5) ten of the 63 sinkholes occurred close enough to structures to cause damage, and only six sinkholes caused damage; (6) ways to minimize potential damage to future homes from sinkhole subsidence are manageable; (7) threats to residents lie in the collapse of heavy walls, brick chimneys, breaks in gas, water, or electrical lines; and (8) location of future subsidence is not predictable. (DP)« less

Detection and Measurement of Land Subsidence Using Global Positioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996-2005

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin T.

2007-01-01

Land subsidence associated with ground-water-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Ground water has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and interferometric synthetic aperture radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley. GPS measurements made at 13 geodetic monuments in 1996 and in 2005 in the southern Coachella Valley indicate that the elevation of the land surface had a net decline of 333 to 22 millimeters ?58 millimeters (1.1 to 0.07 foot ?0.19 foot) during the 9-year period. Changes at 10 of the 13 monuments exceeded the maximum uncertainty of ?58 millimeters (?0.19 foot) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2005. GPS measurements made at 20 geodetic monuments in 2000 and in 2005 indicate that the elevation of the land surface changed -312 to +25 millimeters ?42 millimeters (-1.0 to +0.08 foot ?0.14 foot) during the 5-year period. Changes at 14 of the 20 monuments exceeded the maximum uncertainty of ?42 millimeters (?0.14 foot) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between August 2000 and August 2005. Eight of the fourteen monuments for which subsidence rates could be compared indicate that subsidence rates increased by as much as a factor of 10 between 2000 and 2005 compared with subsidence rates before 2000. InSAR measurements made between May 7, 2003, and September 25, 2005, indicate that land subsidence, ranging from about 75 to 180 millimeters (0.25 to 0.59 foot), occurred in three areas of the Coachella Valley: near Palm Desert, Indian Wells, and La Quinta; the equivalent subsidence rates range from about 3 to more than 6 mm/month (0.01 to 0.02 ft/month). The subsiding areas near Palm Desert, Indian Wells, and La Quinta were previously identified using InSAR measurements for 1996-2000, which indicated that about 35 to 150 mm (0.11 to 0.49 ft) of subsidence occurred during the four-year period; the equivalent subsidence rates range from about 1 to 3 mm/month (0.003 to 0.01 ft/month). Comparison of the InSAR results indicates that subsidence rates have increased 2 to 4 times since 2000 in these three areas. Water-level measurements made at wells near the subsiding monuments and in the three subsiding areas generally indicated that the water levels fluctuated seasonally and declined annually between 1996 and 2005; some water levels in 2005 were at the lowest levels in their recorded histories. The coincident areas of subsidence and declining water levels suggest that aquifer-system compaction may be causing subsidence. If the stresses imposed by the historically lowest water levels exceeded the preconsolidation stress, the aquifer-system compaction and associated land subsidence may be permanent. Although the localized character of the subsidence signals is typical of the type of subsidence characteristically caused by localized ground-water pumping, the subsidence may also be related to tectonic activity in the valley.

Land Subsidence and Aquifer-System Compaction in the Tucson Active Management Area, South-Central Arizona, 1987-2005

USGS Publications Warehouse

Carruth, Rob; Flynn, Pool; Donald, R.; Anderson, Carl E.

2007-01-01

The U.S. Geological Survey monitors land subsidence and aquifer-system compaction caused by ground-water depletion in Tucson Basin and Avra Valley - two of the three alluvial basins within the Tucson Active Management Area. In spring 1987, the Global Positioning System was used to measure horizontal and vertical positions for bench marks at 43 sites to establish a network for monitoring land subsidence in Tucson Basin and Avra Valley. Between 1987 and 2005, the original number of subsidence monitoring stations was gradually increased to more than 100 stations to meet the need for information in the growing metropolitan area. Data from approximately 60 stations common to the Global Positioning System surveys done after an initial survey in 1987 are used to document land subsidence. For the periods of comparison, average land-surface deformation generally is less than the maximum subsidence at an individual station and takes into account land-surface recovery from elastic aquifer-system compaction. Between 1987 and 1998, as much as 3.2 inches of subsidence occurred in Tucson Basin and as much as 4 inches of subsidence occurred in Avra Valley. For the 31 stations that are common to both the 1987 and 1998 Global Positioning System surveys, the average subsidence during the 11-year period was about 0.5 inch in Tucson Basin and about 1.2 inches in Avra Valley. For the approximately 60 stations that are common to both the 1998 and 2002 Global Positioning System surveys, the data indicate that as much as 3.5 inches of subsidence occurred in Tucson Basin and as much as 1.1 inches of subsidence occurred in Avra Valley. The average subsidence for the 4-year period is about 0.4 inch in Tucson Basin and 0.6 inch in Avra Valley. Between the 2002 and the 2005 Global Positioning System surveys, the data indicate that as much as 0.2 inch of subsidence occurred in Tucson Basin and as much as 2.2 inches of subsidence occurred in Avra Valley. The average subsidence for the 3-year period is about 0.7 inch in Avra Valley. Between 1987 and 2004-05, land subsidence was greater in Avra Valley than in Tucson Basin on the basis of the average cumulative subsidence for the stations that were common to the original Global Positioning System survey in 1987. The average total subsidence during the 17- to 18-year period was about 1.3 inches in Tucson Basin and about 2.8 inches in Avra Valley. Three stations in Tucson Basin showed subsidence greater than 4 inches for the period - 5 inches at stations C45 and X419 and 4.1 inches at station PA4. In Avra Valley, two stations showed subsidence for the 17- to 18-year period greater than 4 inches - 4.3 inches at station AV25 and 4.8 inches at station SA105. In 1983, fourteen wells were fitted with borehole extensometers to monitor water-level fluctuations and aquifer-system compaction. Continuous records of water level and aquifer-system compaction indicate that as much as 45 feet of water-level decline and 4 inches of aquifer-system compaction occurred in Tucson Basin from January 1989 through December, 2005. In Avra Valley, extensometer data indicate that as much as 55 feet of water-level decline and 1.7 inches of aquifer-system compaction occurred during the same time period. Rates of compaction vary throughout the extensometer network, with the greater rates of compaction being associated with areas of greater water-level decline and more compressible sediments. In Avra Valley, data from the Global Positioning System surveys indicate that more than half of the total subsidence of the land surface may be the result of aquifer-system compaction below the portion of the aquifer instrumented with the vertical extensometers. For the area in the northern part of Tucson Basin between the Rillito and Santa Cruz rivers, an Interferometric Synthetic Aperture Radar interferogram indicates that about 1.65 inches of subsidence occurred between 2003 and 2006. Between 2002 and 2004, the Global Positioning System

Maps showing water-level declines, land subsidence, and earth fissures in south-central Arizona

USGS Publications Warehouse

Laney, R.L.; Raymond, R.H.; Winikka, C.C.

1978-01-01

From 1915 to 1975, more than 109 million acre-feet of ground water was withdrawn from about 4,500 square miles in Pinal and Maricopa Counties in south-central Arizona. The volume of water withdrawn greatly exceeds the volume of natural recharge, and water levels have been declining since 1923. As a result of the water-level declines, the land surface has subsided, the alluvial deposits have been subjected to stress, and earth fissures have developed. Land subsidence and earth fissures have damaged public and private properties. Subsidence and fissures will continue to occur as long as ground water is being mined and water levels continue to decline. As urban development expands, land subsidence and earth fissures will have an increasing socioeconomic impact. Information on maps includes change in water levels, measurements of land subsidence, and location of earth fissures. A section showing land subsidence between Casa Grande and the Picacho Peak Interchange also is included. Scale 1:250,000. (Woodard-USGS)

Estimated land-surface subsidence in Harris County, Texas, 1915-17 to 2001

USGS Publications Warehouse

Kasmarek, Mark C.; Gabrysch, Robert K.; Johnson, Michaela R.

2009-01-01

Land-surface subsidence, or land subsidence, in Harris County, Texas, which encompasses much of the Houston area, has been occurring for decades. Land subsidence has increased the frequency and extent of flooding, damaged buildings and transportation infrastructure, and caused adverse environmental effects. The primary cause of land subsidence in the Houston area is withdrawal of groundwater, although extraction of oil and gas also has contributed. Throughout most of the 20th century, groundwater was the primary source of municipal, agricultural, and industrial water supply for Harris County. Currently (2009) a transition to surface water as the primary source of supply, guided by a groundwater regulatory plan developed by the Harris-Galveston Subsidence District (2001), is in effect. The aquifers in Harris County contain an abundant amount of potable groundwater, but they also contain layers of clay. Groundwater withdrawals caused compaction of the clay layers, which in turn resulted in the widespread, substantial land-surface subsidence that has occurred in the Houston area.

Land subsidence threats and its management in the North Coast of Java

NASA Astrophysics Data System (ADS)

Sarah, D.; Soebowo, E.

2018-02-01

Cities on the north coast of Java such as Jakarta, Semarang, Pekalongan, and Surabaya are vulnerable to environmental pressures such as sea level change and land subsidence. Land subsidence can be caused by natural and anthropogenic processes. Geologically, the north coastal plain of Java consists of unconsolidated Holocene alluvial deposit. The recent alluvial deposit is prone to compaction, and further aggravated by anthropogenic forces such as groundwater extraction and land development. Understanding the complex interaction of natural and manmade factors is essential to establish mitigation strategy. Although the impacts of land subsidence are widely felt, many do not realize that land subsidence is taking place. This paper presents a brief review of the land subsidence threats in the North coast of Java and proposes a recommendation for suitable management response.

Space geodesy: subsidence and flooding in New Orleans.

PubMed

Dixon, Timothy H; Amelung, Falk; Ferretti, Alessandro; Novali, Fabrizio; Rocca, Fabio; Dokka, Roy; Sella, Giovanni; Kim, Sang-Wan; Wdowinski, Shimon; Whitman, Dean

2006-06-01

It has long been recognized that New Orleans is subsiding and is therefore susceptible to catastrophic flooding. Here we present a new subsidence map for the city, generated from space-based synthetic-aperture radar measurements, which reveals that parts of New Orleans underwent rapid subsidence in the three years before Hurricane Katrina struck in August 2005. One such area is next to the Mississippi River-Gulf Outlet (MRGO) canal, where levees failed during the peak storm surge: the map indicates that this weakness could be explained by subsidence of a metre or more since their construction.

An Integrated Assessment Framework for land subsidence in Delta cities

NASA Astrophysics Data System (ADS)

Bucx, T.; van Ruiten, K.; Erkens, G.

2013-12-01

In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten. Without change, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other delta (and coastal) cities will sink below sea level. Increased flooding and also other wide¬spread impacts of land subsidence result already in damage of billions of dollars per year to roads, embankments, subsurface infrastructure and housing. Moreover the potential damage caused by increased flood risk is around the same amount of money. A major cause for severe land subsidence is excessive groundwater extraction related to rapid urbanization and population growth. A major rethink is needed to resolve the ';hidden' but urgent threat of subsidence in a multi-sectoral perspective. A comprehensive approach is presented to address land subsidence for more sustainable and resilient urban development. Land subsidence is an issue that involves many policy fields, complex technical aspects and governance. There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies and measures that are effective and efficient on both the short and long term. Urban (ground)water management, adaptive flood risk management and related spatial planning strategies should be taken into account. This presentation will introduce and illustrate an Integrated Assessment Framework (IAF) for land subsidence that has been developed in the European FP7 project Subcoast. This framework is based on an integrated (multi-sectoral) approach and can be used to gain insight in the complex aspects of subsidence, to raise awareness and to support decision making on appropriate adaptation strategies and measures. The IAF is addressing all aspects of subsidence: from primary causes, vulnerability, impacts and risks towards responses and solutions. It will also take into account the three spatial layers (Occupation, Network and Base layer), governance aspects and several scenarios (economic and/or climate change). Main questions to be addressed in an integrated approach: what are the main causes, how much is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act? In five case studies a quick-assessment of land subsidence is performed based on this Integrated Assessment Framework. The case studies involve the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented in order to further develop and support a (generic) approach how to deal with subsidence in current and future subsidence-prone areas. Integrated Assessment Framework by Deltares

The Acoustic Signature of Glaciated Margins

NASA Astrophysics Data System (ADS)

Newton, A. M. W.; Huuse, M.

2016-12-01

As climate warms it has become increasingly clear that, in order to fully understand how it might evolve in the future, we need to look for examples of how climate has changed in the past. The Late Cenozoic history of the Arctic Ocean and its surrounding seas has been dominated by glacial-interglacials cycles. This has resulted in major environmental changes in relative sea levels, ice volumes, sea ice conditions, and ocean circulation as marine and terrestrially-based ice sheets waxed and waned. In this work, the acoustic signatures of several glaciated margins in the Northern Hemisphere are investigated and compared. This includes: NW Greenland, West Greenland, East Greenland, mid-Norway, Northern Norway, and the North Sea. These shelf successions preserve a geomorphological record of multiple glaciations and are imaged using seismic reflection data. To date, the majority of work in these areas has tended to focus on the most recent glaciations, which are well known. Here, the focus of the work is to look at the overall stratigraphic setting and how it influences (and is influenced by) the evolution of ice sheets throughout the glacial succession. Landform records are imaged using seismic data to provide a long-term insight into the styles of glaciation on each margin and what relation this may have had on climate, whilst the stratigraphic architectures across each site demonstrate how the inherited geology and tectonic setting can provide a fundamental control on the ice sheet and depositional styles. For example, Scoresby Sund is characterised by significant aggradation that is likely related to subsidence induced by lithospheric cooling rather than rapid glacial deposition, whilst the subsidence of the mid-Norwegian margin can be related to rapid glacial deposition and trapping of sediments behind inversion structures such as the Helland-Hansen Arch. The insights from this multi-margin study allow for regional, basin-wide, glaciological records to be developed and to investigate how marine, marginal-marine, and grounded glacial signatures vary across margins with different geological histories and whether these margins evolved with any synchronicity.

Subsidence Induced Faulting Hazard Zonation Using Persistent Scatterer Interferometry and Horizontal Gradient Mapping in Mexican Urban Areas

NASA Astrophysics Data System (ADS)

Cabral-Cano, E.; Cigna, F.; Osmanoglu, B.; Dixon, T.; Wdowinski, S.

2011-12-01

Subsidence and faulting have affected Mexico city for more than a century and the process is becoming widespread throughout larger urban areas in central Mexico. This process causes substantial damages to the urban infrastructure and housing structures and will certainly become a major factor to be considered when planning urban development, land use zoning and hazard mitigation strategies in the next decades. Subsidence is usually associated with aggressive groundwater extraction rates and a general decrease of aquifer static level that promotes soil consolidation, deformation and ultimately, surface faulting. However, local stratigraphic and structural conditions also play an important role in the development and extension of faults. In all studied cases stratigraphy of the uppermost sediment strata and the structure of the underlying volcanic rocks impose a much different subsidence pattern which is most suitable for imaging through satellite geodetic techniques. We present examples from several cities in central Mexico: a) Mexico-Chalco. Very high rates of subsidence, up to 370 mm/yr are observed within this lacustrine environment surrounded by Pliocene-Quaternary volcanic structures. b) Aguascalientes where rates up to 90 mm/yr in the past decade are observed, is controlled by a stair stepped N-S trending graben that induces nucleation of faults along the edges of contrasting sediment package thicknesses. c) Morelia presents subsidence rates as high as 80 mm/yr. Differential deformation is observed across major basin-bounding E-W trending faults and with higher subsidence rates on their hanging walls, where the thickest sequences of compressible Quaternary sediments crop out. Our subsidence and faulting study in urban areas of central Mexico is based on a horizontal gradient analysis using displacement maps from Persistent Scatterer InSAR that allows definition of areas with high vulnerability to surface faulting. Correlation of the surface subsidence pattern through satellite geodesy and surface faults show that the principal factor for defining these hazardous areas is best determined not by solely using the subsidence magnitude rates but rather by using a combined magnitude and horizontal subsidence gradient analysis. This approach is used as the basis for the generation of subsidence-induced surface faulting hazard maps for the studied urban areas.

Post-emplacement cooling and contraction of lava flows: InSAR observations and thermal model for lava fields at Hekla volcano, Iceland

NASA Astrophysics Data System (ADS)

Wittmann, Werner; Dumont, Stephanie; Lavallee, Yan; Sigmundsson, Freysteinn

2016-04-01

Gradual post-emplacement subsidence of lava flows has been observed at various volcanoes, e.g. Okmok volcano in Alaska, Kilauea volcano on Hawaii and Etna volcano on Sicily. In Iceland, this effect has been observed at Krafla volcano and Hekla volcano. The latter was chosen as a case study for investigating subsidence mechanisms, specifically thermal contraction. Effects like gravitational loading, clast repacking or creeping of a hot and liquid core can contribute to subsidence of emplaced lava flows, but thermal contraction is considered being a crucial effect. The extent to which it contributes to lava flow subsidence is investigated by mapping the relative movement of emplaced lava flows and flow substrate, and modeling the observed signal. The slow vegetation in Iceland is advantageous for Interferometric Synthetic Aperture Radar (InSAR) and offers great coherence over long periods after lava emplacement, expanding beyond the outlines of lava flows. Due to this reason, InSAR observations over volcanoes in Iceland have taken place for more than 20 years. By combining InSAR tracks from ERS, Envisat and Cosmo-SkyMed satellites we gain six time series with a total of 99 interferograms. Making use of the high spatial resolution, a temporal trend of vertical lava movements was investigated over a course of over 23 years over the 1991 lava flow of Hekla volcano, Iceland. From these time series, temporal trends of accumulated subsidence and subsidence velocities were determined in line of sight of the satellites. However, the deformation signal of lava fields after emplacement is vertically dominated. Subsidence on this lava field is still ongoing and subsidence rates vary from 14.8 mm/year in 1995 to about 1.0 mm/year in 2014. Fitting a simple exponential function suggests a exponential decay constant of 5.95 years. Additionally, a one-dimensional, semi-analytical model was fitted to these data. While subsidence due to phase change is calculated analytically, subsidence due to thermal contraction gives additional subsidence, which is calculated numerically. Inversions were carried out for initial lava thickness, thermal expansivity, thermal diffusivity, latent heat and specific heat as the crucial parameters governing lava flow subsidence.

Determination of land subsidence related to ground-water-level declines using Global Positioning System and leveling surveys in Antelope Valley, Los Angeles and Kern counties, California, 1992

USGS Publications Warehouse

Ikehara, M.E.; Phillips, S.P.

1994-01-01

A large-scale, land-subsidence monitoring network for Antelope Valley, California, was established, and positions and elevations for 85 stations were measured using Global Positioning System geodetic surveying in spring 1992. The 95-percent confidence (2@) level of accuracy for the elevations calculated for a multiple-constraint adjustment generally ranged from +0.010 meter (0.032 foot) to +0.024 meter (0.078 foot). The magnitudes and rates of land subsidence as of 1992 were calculated for several periods for 218 bench marks throughout Antelope Valley. The maximum measured magnitude of land subsidence that occurred between 1926 and 1992 was 6.0 feet (1.83 meters) at BM 474 near Avenue I and Sierra Highway. Measured or estimated subsidence of 2-7 feet (.61-2.l3 meters) had occurred in a 210- square-mile (542-square-kilometer) area of Antelope Valley, generally bounded by Avenue K, Avenue A, 90th Street West, and 120th Street East, during the same period. Land subsidence in Antelope Valley is caused by aquifer-system compaction, which is related to ground-water-level declines and the presence of fine-grained, compressible sediments. Comparison of potentiomethric-surface, water-level decline, and subsidence-rate maps for several periods indicated a general correlation between water-level declines and the distribution and rate of subsidence in the Lancaster ground-water subbasin. A conservative estimate of the amount of the reduction in storage capacity of the aquifer system in the Lancaster subbasin is about 50,000 acre-feet in the area that has been affected by more than one foot (.30 meters) of subsidence as of 1992. Information on the history of ground-water levels and the distribution and thickness of fine-grained compressible sediments can be used to mitigate continued land subsidence. Future monitoring of ground-water levels and land-surface elevations in subsidence-sensitive regions of Antelope Valley may be an effective means to manage land subsidence.

Update on subsidence at the Wairakei-Tauhara geothermal system, New Zealand

USGS Publications Warehouse

Allis, R.; Bromley, C.; Currie, S.

2009-01-01

The total subsidence at the Wairakei field as a result of 50 years of geothermal fluid extraction is 15 ?? 0.5 m. Subsidence rates in the center of the subsidence bowl have decreased from over 450 mm/year during the 1970s to 80-90 mm/year during 2000-2007. The location of the bowl, adjacent to the original liquid outflow zone of the field, has not changed significantly. Subsidence at the Tauhara field due to Wairakei production was not as well documented in the early years but appeared later and has been less intense than at Wairakei. Total subsidence of 2.6 ?? 0.5 m has also occurred close to the original liquid outflow zone of this field, and maximum subsidence rates in this area today are in the 80-100 mm/year range. In the western part of the Wairakei field, near the area of hot upflow, subsidence rates have approximately doubled during the last 20 years to 30-50 mm/year. This increase appears to be have been caused by declining pressure in the underlying steam zone in this area, which is tapped by some production wells. At Tauhara field, two areas of subsidence have developed since the 1990s with rates of 50-65 mm/year. Although less well-determined, this subsidence may also be caused by declining pressure in shallow steam zones. The cause of the main subsidence bowls in the Wairakei-Tauhara geothermal system is locally high-compressibility rocks within the Huka Falls Formation (HFF), which are predominantly lake sediments and an intervening layer of pumice breccia. At Wairakei, casing deformation suggests the greatest compaction is at 150-200 m depth. The cause of the large compressibility is inferred to be higher clay content in the HFF due to intense hydrothermal alteration close to the natural fluid discharge areas. Future subsidence is predicted to add an additional 2-4 m to the Wairakei bowl, and 1-2 m elsewhere, but these estimates depend on the assumed production-injection scenarios.

An Integrated Approach for the Assessment of the Natural and Anthropogenic Controls on Land Subsidence in the Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Othman, A.; Sultan, M.; Ahmed, M.; Alharbi, T.; Gebremichael, E.; Emil, M.

2015-12-01

Recent land subsidence incidences in the Kingdom of Saudi Arabia (KSA) resulted in loss in life and property. In this study, an integrated approach is adopted to accomplish the following: (1) map the spatial distribution of areas that are witnessing land subsidence, (2) quantify the rates of land subsidence, and (3) identify the factors causing the observed subsidence. A three-fold approach is applied: (1) use of interferometric techniques to assess the spatial distribution of land subsidence and to quantify the rates of subsidence, (2) generate a GIS database to encompass all relevant data and derived products, and (3) correlate findings from the radar exercise with relevant spatial and temporal datasets (e.g., remote sensing, geology, fluid extraction rates, distribution of urban areas, etc.). Three main areas were selected: (1) central and northern parts of the KSA, (2) areas surrounding the Ghawar oil/gas field, and (3) the Harrat Lunayyir volcanic field. Applications of two-pass, three-pass, and SBAS radar interferometric techniques over central KSA revealed the following: (1) subsidence rates of up to -15 mm/yr were detected; the spatial distribution of the subsided areas that were extracted using the various interferometric techniques are similar, (2) subsided areas correlated spatially with the distribution of: (a) areas with high groundwater extraction rates as evidenced from the analysis of field and Gravity Recovery and Climate Experiment (GRACE) data, (b) agricultural plantations as evidenced from the analysis of field and temporal Landsat data, (c) urban areas (e.g., Buraydah City), (d) outcrops of carbonates and anhydrite formations (e.g., Khuff and Jilh formations), (3) subsidence could be related to more than one parameter. Similar research activities are underway in northern KSA and in areas surrounding the Ghawar oil/gas and the Harrat Lunayyir volcanic fields to assess the distribution and factors controlling land deformation in those areas.

Subsidence Serves as an Indicator of Groundwater Arsenic Risk in the San Joaquin Valley, California

NASA Astrophysics Data System (ADS)

Smith, R.; Knight, R. J.; Fendorf, S. E.

2016-12-01

Groundwater arsenic concentrations dominantly result from anaerobic conditions. Within aquifers, clays are typically the major hosts of solid-phase arsenic, and clay layers often have restricted oxygen supply, resulting in anaerobic conditions and the concomitant relase of arsenic to groundwater. But it is not until water is drawn from the clay layers, through over-pumping of aquifers, that arsenic enters the water supply. Due to the mechanical properties of clays, the volume of groundwater withdrawn is effectively approximated by their vertical deformation, the sum of which is expressed at the surface as subsidence. As a result, subsidence can serve as an indicator, or "early warning system", of the presence of arsenic in the pumped groundwater. In the San Joaquin Valley of California, there has been significant subsidence due to groundwater extraction from clays for nearly a century. Historical subsidence in this area has been measured with leveling surveys, GPS and extensometers, and has been reproduced in groundwater models. More recent subsidence can be measured directly using Interferometric Synthetic Aperture Radar (InSAR). We use recent (post-2007) arsenic level data from the southern portion of the San Joaquin Valley to train a random forest model. Predictors in the model include historical (pre-2002) estimates of subsidence, more recent (2007-2011) InSAR estimates of subsidence, and other predictors representing additional mechanisms that could affect arsenic levels in groundwater, such as groundwater flow, redox potential and position in the basin. We find that recent subsidence is a strong predictor of arsenic levels; historical subsidence could have some impact but is less significant. These results indicate that avoiding over-pumping of the aquifer may improve water quality over a time period on the order of 10 years. Incorporating subsidence into arsenic prediction maps can improve our ability to identify and manage areas that have a higher risk of arsenic contamination due to removal of groundwater from clays.

Subsidence driving forces in large Delta Plain

NASA Astrophysics Data System (ADS)

Grall, C.; Steckler, M. S.

2017-12-01

Recent studies show large variability in subsidence rates among large delta plains that directly impact coastal management of these highly vulnerable environments. Observations show both significant spatial variation in subsidence across each delta, as well as large differences in magnitude between different deltas. This variability raises the question of what are the driving forces that control subsidence in large delta plains that this study aims to address. Subsidence and sediment compaction is studied in 4 end-member large Delta Plains: the Ganges-Brahmaputra, the Mekong, the Mississippi and the Nile. Those large delta plains drastically contrast in subsidence rates (from values to several mm/yr to several cm/yr), in the nature of the sediment (notably in clay and organic matter content), and in the volume of sediment supplied by the large rivers that feed those coastal environments. The volume of sediment deposited in each delta plain during the Holocene is estimated and the compaction of the underlying sedimentary column is computed by using a backstripping approach. Sediment compaction behaviors are defined accordingly to the observed clay, silt and organic contents, and the rate of subsidence associated with compaction is determined. Results suggest that about 2/3 of observed Holocene subsidence may be associated with the mechanical and chemical compaction of the underlying sedimentary column due to the load of sediment deposited. The compaction appears to be significantly higher in delta plains characterized by a high sediment input and a high organic matter and clay content. Thus, the observed subsidence rates in the (muddy) Mekong delta appear to be one order of magnitude higher than other delta plains. In contrast, subsidence rates are modest in the Ganges-Brahmaputra, the Mississippi and the Nile delta plains, except away from the major rivers where deposits are muddier.

Correlating the subsidence pattern and land use in Bandung, Indonesia with both Sentinel-1/2 and ALOS-2 satellite images

NASA Astrophysics Data System (ADS)

Du, Zheyuan; Ge, Linlin; Ng, Alex Hay-Man; Zhu, Qinggaozi; Yang, Xihua; Li, Liyuan

2018-05-01

Continuous research has been conducted in Bandung City, West Java province, Indonesia over the past two decades. Previous studies carried out in a regional-scale might be useful for estimating the correlation between land subsidence and groundwater extraction, but inadequate for local safety management as subsidence may vary over different areas with detailed characters. This study is focused primarily on subsidence phenomenon in local, patchy and village scales, respectively, with Sentinel-1 and ALOS-2 dataset acquired from September 2014 to July 2017. The Sentinel-1 derived horizontal movement map confirmed that the vertical displacement is dominant of the Line-of-Sight (LoS) subsidence. Moreover, both Sentinel-1 and ALOS-2 derived InSAR measurements were cross-validated with each other. In order to understand the subsidence in a more systematic way, six 10-cm subsidence zones have been selected known as Zone A-F. Further analyses conducted over multiple scales show that industrial usage of groundwater is not always the dominant factor that causes the land subsidence and indeed it does not always create large land subsidence either. Regions experiencing subsidence is due to a combined impact of a number of factors, e.g., residential, industrial or agricultural activities. The outcome of this work not only contributes to knowledge on efficient usage of the satellite-based monitoring networks, but also assists developing the best hazard mitigation plans. In the future work, as we cannot draw the conclusion which is the dominant factor within each sub-zone due to the lack of statistical data, e.g., the groundwater consumption rates per square kilometre for different land types, further datasets are still needed to examine the core factor.

Siting of prison complex above abandoned underground coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marino, G.G.

1998-10-01

This paper discusses in detail the process undertaken to mitigate the effects of any future mine subsidence on prison structures proposed above old abandoned underground workings. The site for a proposed prison complex purchased by the state of Indiana was located in west-central Indiana and was undermined by an old abandoned room and pillar mine. Based on a study of the mine map and subsurface verification of the extent of mining it was determined that all prison buildings and important structures could be placed above solid coal to the north. However, one masonry building was located within the potential drawmore » zone of mine works that still contained significant mine voids. Based on empirical data the subsidence potential was estimated and the building was designed accordingly to be mine subsidence resistant. It was decided that a phase 2 prison complex should be constructed adjacent to and just south of the phase 1 complex. This complex would be directly above the underground workings. Subsequently, an extensive subsurface investigation program was undertaken to (1) ascertain whether or not mine areas where buildings would be located were already collapsed and thus only nominal, if any, subsidence could occur in the future and (2) verify the presence of solid coal areas within the mine as indicated on the mine map. Based on all the site information gathered subsidence profiles were developed from an empirical database of subsidence events in the Illinois coal basin. As a result of this work many structures on the site required no or nominal subsidence considerations. However, for others that could be affected potentially by future subsidence movement preliminary subsidence resistant designs were completed using the expected level of potential subsidence movement.« less

Acid mine drainage and subsidence: effects of increased coal utilization.

PubMed Central

Hill, R D; Bates, E R

1979-01-01

The increases above 1975 levels for acid mine drainage and subsidence for the years 1985 and 2000 based on projections of current mining trends and the National Energy Plan are presented. No increases are projected for acid mine drainage from surface mines or waste since enforcement under present laws should control this problem. The increase in acid mine drainage from underground mines is projected to be 16 percent by 1985 and 10 percent by 2000. The smaller increase in 2000 over 1985 reflects the impact of the PL 95-87 abandoned mine program. Mine subsidence is projected to increase by 34 and 115 percent respectively for 1985 and 2000. This estimate assumes that subsidence will parallel the rate of underground coal production and that no new subsidence control measures are adopted to mitigate subsidence occurrence. PMID:540617

Cenozoic forearc tectonics in northeastern Japan: Relationships between outer forearc subsidence and plate boundary kinematics

NASA Astrophysics Data System (ADS)

Regalla, Christine

Here we investigate the relationships between outer forearc subsidence, the timing and kinematics of upper plate deformation and plate convergence rate in Northeast Japan to evaluate the role of plate boundary dynamics in driving forearc subsidence. The Northeastern Japan margin is one of the first non-accretionary subduction zones where regional forearc subsidence was argued to reflect tectonic erosion of large volumes of upper crustal rocks. However, we propose that a significant component of forearc subsidence could be the result of dynamic changes in plate boundary geometry. We provide new constraints on the timing and kinematics of deformation along inner forearc faults, new analyses of the evolution of outer forearc tectonic subsidence, and updated calculations of plate convergence rate. These data collectively reveal a temporal correlation between the onset of regional forearc subsidence, the initiation of upper plate extension, and an acceleration in local plate convergence rate. A similar analysis of the kinematic evolution of the Tonga, Izu-Bonin, and Mariana subduction zones indicates that the temporal correlations observed in Japan are also characteristic of these three non-accretionary margins. Comparison of these data with published geodynamic models suggests that forearc subsidence is the result of temporal variability in slab geometry due to changes in slab buoyancy and plate convergence rate. These observations suggest that a significant component of forearc subsidence at these four margins is not the product of tectonic erosion, but instead reflects changes in plate boundary dynamics driven by variable plate kinematics.

Physical assessment of coastal vulnerability under enhanced land subsidence in Semarang, Indonesia, using multi-sensor satellite data

NASA Astrophysics Data System (ADS)

Husnayaen; Rimba, A. Besse; Osawa, Takahiro; Parwata, I. Nyoman Sudi; As-syakur, Abd. Rahman; Kasim, Faizal; Astarini, Ida Ayu

2018-04-01

Research has been conducted in Semarang, Indonesia, to assess coastal vulnerability under enhanced land subsidence using multi-sensor satellite data, including the Advanced Land Observing Satellite (ALOS) Phased Array type L-band SAR (PALSAR), Landsat TM, IKONOS, and TOPEX/Poseidon. A coastal vulnerability index (CVI) was constructed to estimate the level of vulnerability of a coastline approximately 48.68 km in length using seven physical variables, namely, land subsidence, relative sea level change, coastal geomorphology, coastal slope, shoreline change, mean tidal range, and significant wave height. A comparison was also performed between a CVI calculated using seven parameters and a CVI using six parameters, the latter of which excludes the land subsidence parameter, to determine the effects of land subsidence during the coastal vulnerability assessment. This study showed that the accuracy of coastal vulnerability was increased 40% by adding the land subsidence factor (i.e., CVI 6 parameters = 53%, CVI 7 parameters = 93%). Moreover, Kappa coefficient indicated very good agreement (0.90) for CVI 7 parameters and fair agreement (0.3) for CVI 6 parameters. The results indicate that the area of very high vulnerability increased by 7% when land subsidence was added. Hence, using the CVI calculation including land subsidence parameters, the very high vulnerability area is determined to be 20% of the total coastline or 9.7 km of the total 48.7 km of coastline. This study proved that land subsidence has significant influence on coastal vulnerability in Semarang.

Leveraging Subsidence in Permafrost with Remotely Sensed Active Layer Thickness (ReSALT) Products

NASA Astrophysics Data System (ADS)

Schaefer, K. M.; Chen, A.; Chen, J.; Chen, R. H.; Liu, L.; Michaelides, R. J.; Moghaddam, M.; Parsekian, A.; Tabatabaeenejad, A.; Thompson, J. A.; Zebker, H. A.; Meyer, F. J.

2017-12-01

The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence in permafrost regions. Seasonal subsidence results from the expansion of soil water into ice as the surface soil or active layer freezes and thaws each year. Subsidence trends result from large-scale thaw of permafrost and from the melting and subsequent drainage of excess ground ice in permafrost-affected soils. The attached figure shows the 2006-2010 average seasonal subsidence from ReSALT around Barrow, Alaska. The average active layer thickness (the maximum surface thaw depth during summer) is 30-40 cm, resulting in an average seasonal subsidence of 1-3 cm. Analysis of the seasonal subsidence and subsidence trends provides valuable insights into important permafrost processes, such as the freeze/thaw of the active layer, large-scale thawing due to climate change, the impact of fire, and infrastructure vulnerability. ReSALT supports the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential NASA-ISRO Synthetic Aperture Radar (NISAR) product. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. Here we present examples of ReSALT products in Alaska to highlight the untapped potential of the InSAR technique to understand permafrost dynamics, with a strong emphasis on the underlying processes that drive the subsidence.

The sinking Mekong delta; modeling 25 years of groundwater extraction and subsidence

NASA Astrophysics Data System (ADS)

Minderhoud, P. S. J.; Erkens, G.; Pham, H. V.; Bui, V. T.; Erban, L. E.; Kooi, H.; Stouthamer, E.

2017-12-01

The Vietnamese Mekong delta, the third's largest delta in the world, is experiencing annual subsidence rates up to several centimeters. As a result, vulnerability to flooding and storm surges, salinization and, ultimately, permanent inundation increases. Extraction of groundwater from the soft deltaic subsurface can be a major driving mechanism of subsidence, however a quantification of temporal and spatial impact to subsidence in the Mekong delta was not done yet. We developed a delta-wide, 3D hydrogeological model coupled to a 1D geotechnical module to quantify the contribution of excessive groundwater exploitation to subsidence. The modelling period of 25 years captures the period in which the hydrogeological state of the delta transforming from almost undisturbed to a situation with increasing aquifer depletion. Our model provides a quantitative spatially-explicit assessment of groundwater extraction-induced subsidence for the entire Mekong delta since the start of widespread depletion of the groundwater reserves. Over the past decades subsidence related to groundwater extraction has accelerated towards the highest sinking rates at present. During the past 25 years, the delta sank on average 18 cm, with areas over 30 cm. Currently the delta experiences an average subsidence rate of 1.1 cm yr-1, some areas subside over 2.5 cm yr-1, due to groundwater exploitation. These rates outpace global sea level rise almost by an order of magnitude. Given the increasing trends in groundwater demand in the delta, the current rates are likely to increase in the near future.

U.S. Geological Survey Subsidence Interest Group conference, Edwards Air Force Base, Antelope Valley, California, November 18-19, 1992; abstracts and summary

USGS Publications Warehouse

Prince, Keith R.; Galloway, Devin L.; Leake, Stanley A.

1995-01-01

Land subsidence, the loss of surface elevation as a result of the removal of subsurface support, affects every state in the United States. More than 17,000 mi2 of land in the United States has been lowered by the various processes that produce land subsidence with annual costs from resulting flooding and structural damage that exceed $125 million. It is estimated that an additional $400 million is spent nationwide in attempts to control subsidence. Common causes of land subsidence include the removal of oil, gas, and water from underground reservoirs; dissolution of limestone aquifers (sinkholes); underground mining activities; drainage of organic soils; and hydrocompaction (the initial wetting of dry soils). Overdrafting of aquifers is the major cause of areally extensive land subsidence, and as ground-water pumping increases, land subsidence also will increase. Land subsidence and its effects on engineering structures have been recognized for centuries, but it was not until this century that the processes that produce land subsidence were identified and understood. In 1928, while working with field data from a test of the Dakota Sandstone aquifer, O.E. Meinzer of the U.S. Geological Survey recognized the compressibility of aquifers. Around the same time, Karl Terzaghi, a soil scientist working at Harvard University, developed the one-dimensional consolidation theory that provided a quantitative means of predicting soil compaction resulting from the drainage of compressible soils. Thus, with the recognition of the compressibility of aquifers (Meinzer), and the development of a quantitative means of predicting soil compaction as a consequence of the reduction of intergranular pore pressure (Terzaghi), the theory of aquifer-system compaction was formed. With the widespread availa- bility of electric power in rural areas, and the advent of the deep turbine pump, ground-water withdrawals increased dramatically throughout the country in the 1940's and 1950's. Along with this unprecedented increase in pumpage, substantial amounts of land subsidence were observed in several areas of the United States, most notably in Arizona, California, and Texas. Beginning in 1955, under the direction of Joseph Poland, the Geological Survey began the "Mechanics of Aquifers Project," which focused largely on the processes that resulted in land subsidence due to the withdrawal of ground water. This research team gained international renown as they advanced the scientific understanding of aquifer mechanics and land-subsidence theory. The results of field studies by members of this research group not only verified the validity of the application of Terzaghi's consolidation theory to compressible aquifers, but they also provided definitions, methods of quantification, and confirmation of the interrelation among hydraulic head declines, aquifer-system compaction, and land subsidence. In addition to conducting pioneering research, this group also formed a "center of expertise," providing a focal point within the Geological Survey for the dissemination of technology and scientific understanding in aquifer mechanics. However, when the "Mechanics of Aquifers Project" was phased out in 1984, the focal point for technology transfer no longer existed. Interest among various state and local agencies in land subsidence has persisted, and the Geological Survey has continued to participate in a broad spectrum of cooperative and Federally funded projects in aquifer mechanics and land subsidence. These projects are designed to identify and monitor areas with the potential for land subsidence, to conduct basic research in the processes that control land subsidence and the development of earth fissures, as well as to develop new quantitative tools to predict aquifer-system deformation. In 1989 an ad hoc "Aquifer Mechanics and Subsidence Interest Group" (referred to herein as the "Subsidence Interest Group") was formed

Modeling of reservoir compaction and surface subsidence at South Belridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, K.S.; Chan, C.K.; Prats, M.

1995-08-01

Finite-element models of depletion-induced reservoir compaction and surface subsidence have been calibrated with observed subsidence, locations of surface fissures, and regions of subsurface casing damage at South Belridge and used predictively for the evaluation of alternative reservoir-development plans. Pressure maintenance through diatomite waterflooding appears to be a beneficial means of minimizing additional subsidence and fissuring as well as reducing axial-compressive-type casing damage.

Simulating the hydrologic cycle in coal mining subsidence areas with a distributed hydrologic model

PubMed Central

Wang, Jianhua; Lu, Chuiyu; Sun, Qingyan; Xiao, Weihua; Cao, Guoliang; Li, Hui; Yan, Lingjia; Zhang, Bo

2017-01-01

Large-scale ground subsidence caused by coal mining and subsequent water-filling leads to serious environmental problems and economic losses, especially in plains with a high phreatic water level. Clarifying the hydrologic cycle in subsidence areas has important practical value for environmental remediation, and provides a scientific basis for water resource development and utilisation of the subsidence areas. Here we present a simulation approach to describe interactions between subsidence area water (SW) and several hydrologic factors from the River-Subsidence-Groundwater Model (RSGM), which is developed based on the distributed hydrologic model. Analysis of water balance shows that the recharge of SW from groundwater only accounts for a small fraction of the total water source, due to weak groundwater flow in the plain. The interaction between SW and groundwater has an obvious annual cycle. The SW basically performs as a net source of groundwater in the wet season, and a net sink for groundwater in the dry season. The results show there is an average 905.34 million m3 per year of water available through the Huainan coal mining subsidence areas (HCMSs). If these subsidence areas can be integrated into water resource planning, the increasingly precarious water supply infrastructure will be strengthened. PMID:28106048

Trends and causes of historical wetland loss, Sabine National Wildlife Refuge, southwest Louisiana

USGS Publications Warehouse

Bernier, Julie C.; Morton, Robert A.; Kelso, Kyle W.

2011-01-01

The thickness of the uppermost Holocene sediments (peat and organic-rich mud) and the elevation of stratigraphic contacts were compared at marsh and open-water sites across areas of formerly continuous marsh to estimate magnitudes of recent elevation loss caused by vertical erosion and subsidence. Results of these analyses indicate that erosion greatly exceeded subsidence at most of the core sites, although both processes have contributed to historical wetland loss. Comparison of these results with results of our prior studies indicates that magnitudes of subsidence and total accommodation space that formed in the western chenier plain were less than those in the delta plain. Compared with the delta plain, where subsidence generally exceeded erosion and peat thicknesses were so great that peat was preserved even where erosion was greater than subsidence, the SNWR peats are thin and were absent (eroded) at most open-water sites. Although historical subsidence rates in the chenier plain are substantially lower than most of the same rates in the delta plain, the temporal and spatial trends of rapid wetland loss, highest rates of land-surface subsidence, and high rates of oil-and-gas production are similar, indicating that historical wetland loss was likely initiated by similar processes (deep-subsurface subsidence) in both regions.

Land subsidence in Tianjin for 2015 to 2016 revealed by the analysis of Sentinel-1A with SBAS-InSAR

NASA Astrophysics Data System (ADS)

Guo, Jiming; Hu, Jiyuan; Li, Bing; Zhou, Lv; Wang, Wei

2017-04-01

It has been suggested that Tianjin, China, has significant land subsidence due to excessive extraction of water. Although it is presently under control, the land subsidence around Tianjin suburbs in recent years should not be ignored. However, existing research work on land subsidence is based on traditional synthetic aperture radar satellite images in which the research time spans are mainly before 2012. An advanced time-series method, namely small baselines subset (SBAS) technique, is applied to a total of 27 Sentinel-1A images over Tianjin acquired between May 31, 2015, and May 13, 2016, to derive the subsidence magnitude and distribution of Tianjin. Furthermore, the overall and quantitative validations of SBAS-derived results are implemented. First, the overall subsidence distribution derived by SBAS is compared with the annual report of land subsidence in Tianjin 2015, which shows the same subsidence trend and distribution. Then, 44 benchmarks and 2 continuously operating reference station datasets, i.e., CH01 and XQYY, are processed to provide a specific validation of SBAS-derived results of Sentinel-1A. Finally, through investigation, an interpretation from two aspects of groundwater extraction and geological structures of the surrounding Wangqingtuo settlement funnel area is given.

Houston-Galveston Bay area, Texas, from space; a new tool for mapping land subsidence

USGS Publications Warehouse

Stork, Sylvia V.; Sneed, Michelle

2002-01-01

Interferometric Synthetic Aperture Radar (InSAR) is a powerful new tool that uses radar signals to measure displacement (subsidence and uplift) of the Earth's crust at an unprecedented level of spatial detail and high degree of measurement resolution.The Houston-Galveston Bay area, possibly more than any other metropolitan area in the United States, has been adversely affected by land subsidence. Extensive subsidence, caused mainly by ground-water pumping but also by oil and gas extraction, has increased the frequency of flooding, caused extensive damage to industrial and transportation infrastructure, motivated major investments in levees, reservoirs, and surfacewater distribution facilities, and caused substantial loss of wetland habitat. Ongoing patterns of subsidence in the Houston area have been carefully monitored using borehole extensometers, Global Positioning System (GPS) and conventional spirit-leveling surveys, and more recently, an emerging technology—Interferometric Synthetic Aperture Radar (InSAR)—which enables development of spatially-detailed maps of land-surface displacement over broad areas. This report, prepared by the U.S. Geological Survey (USGS) in cooperation with the U.S. Fish and Wildlife Service, briefly summarizes the history of subsidence in the area and the local consequences of subsidence and describes the use of InSAR as one of several tools in an integrated subsidence-monitoring program in the area.

Using Persistent Scatterers Interferometry to create a subsidence map of the Nile Delta in Egypt

NASA Astrophysics Data System (ADS)

Bouali, E. Y.; Sultan, M.; Becker, R.; Cherif, O.

2013-12-01

Inhabitants of the Nile Delta in Egypt, especially those who live around the coast, are threatened by two perpetual hazards: (1) sea level rise and encroachment from the Mediterranean Sea and (2) land subsidence that is inherent in deltaic environments. With cities like Alexandria and Port Said currently only one meter above sea level, it is important to understand the nature of the sea level rise and land subsidence, both spatially and temporally, and to be able to quantify these hazards. The magnitude of sea level rise has been actively monitored in stations across the Mediterranean Sea; the subsidence of the Nile Delta, as a whole system however, has not been adequately quantified. We have employed the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique known as Persistent Scatterers Interferometry (PSI) across the entire northern parts of the Nile Delta. A dataset of 106 ENVISAT single look complex (SLC) scenes (four descending tracks: 164, 207, 436, and 479) acquired throughout the time period 2003 to 2010 were obtained from the European Space Agency and utilized for radar interferometric purposes. Multiple combinations of these scenes - used for output optimization and validation - were processed. Due to the nature of the PSI technique, subsidence rates calculated using this technique are values measured from cities and urban areas - where PSI works well. The methodology of choice is to calculate the subsidence rates on a city-by-city basis by: (1) choosing an urban area and cutting the SLC scene stack down to a small area (25 - 200 km2); (2) processing this area multiple times using difference scene and parameter combinations in order to best optimize persistent scatterer (PS) abundance and ground displacement measurements; (3) calibrating the relative ground motion measured by PSI to known locations of minimal subsidence rates. The final result is a spatial representation of the subsidence rates across the Nile Delta in Egypt. Measured subsidence rates vary widely across the Nile Delta, with the highest rates occurring in cities near the mouth of the Damietta branch of the Nile River and around the Mansala Lagoon, such as Ras El Bar (up to 15 mm/year), Damietta (up to 10 mm/year), and Port Said (up to 7 mm/year). The complexity of these subsidence rates is spatially evident: many cities display a wide range of subsidence rates - for example Port Said, where a majority of the city is undergoing minimal to no subsidence (< 1 mm/year) there are two regions - near the Mediterranean coast and near the Mansala Lagoon - where subsidence rates are quite high (5-7 mm/year). There are also a few overall trends observed across the delta: (1) subsidence rates are greatest in the northeast region of the delta (average: > 5 mm/year) than anywhere else (e.g., average western subsidence: 1-4 mm/year) and (2) cities generally more proximal to the Mediterranean coast exhibit greater subsidence rates (average subsidence rates: Ras El Bar: 8 mm/year, Port Said: 5 mm/year, and Damietta: 6 mm/year)than cities in the middle (e.g., Mansoura and Al Mahallah: 4 mm/year) or south regions (e.g., Tanta: <4 mm/year) of the delta.

Subsidence Induced by Underground Extraction

USGS Publications Warehouse

Galloway, Devin L.

2016-01-01

Subsidence induced by underground extraction is a class of human-induced (anthropogenic) land subsidence that principally is caused by the withdrawal of subsurface fluids (groundwater, oil, and gas) or by the underground mining of coal and other minerals.

Seismic reflection characteristics of naturally-induced subsidence affecting transportation

USGS Publications Warehouse

Miller, R.D.; Xia, J.; Steeples, D.W.

2009-01-01

High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipelines can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure. ?? China University of Geosciences (Wuhan) and Springer-Verlag GmbH 2009.

Anthropogenic and geologic influences on subsidence in the vicinity of New Orleans, Louisiana

NASA Astrophysics Data System (ADS)

Jones, Cathleen E.; An, Karen; Blom, Ronald G.; Kent, Joshua D.; Ivins, Erik R.; Bekaert, David

2016-05-01

New measurements of ongoing subsidence of land proximal to the city of New Orleans, Louisiana, and including areas around the communities of Norco and Lutcher upriver along the Mississippi are reported. The rates of vertical motion are derived from interferometric synthetic aperture radar (InSAR) applied to Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data acquired on 16 June 2009 and 2 July 2012. The subsidence trends are similar to those reported for 2002-2004 in parts of New Orleans where observations overlap, in particular in Michoud, the 9th Ward, and Chalmette, but are measured at much higher spatial resolution (6 m). The spatial associations of cumulative surface movements suggest that the most likely drivers of subsidence are groundwater withdrawal and surficial drainage/dewatering activities. High subsidence rates are observed localized around some major industrial facilities and can affect nearby flood control infrastructure. Substantial subsidence is observed to occur rapidly from shallow compaction in highly localized areas, which is why it could be missed in subsidence surveys relying on point measurements at limited locations.

Preliminary survey and performance of land subsidence in North Semarang Demak

NASA Astrophysics Data System (ADS)

Yuwono, B. D.; Abidin, H. Z.; Gumilar, I.; Andreas, H.; Awaluddin, M.; Haqqi, K. F.; Khoirunisa, R.

2016-05-01

Land subsidence in Semarang is a severe hazard threatening people and urban infrastructure. Land subsidence is suspected expand to North Demak. It shows that has been leading to severe and costly damages to urban infrastructure such as buildings and roads. Another disaster like flooding will ruin the city frequently and is increasingly severely affecting the living conditions. The Principle of land subsidence monitoring with a GPS is to determine the coordinates of a point on a carefully selected location and are conducted periodically at regular. By studying the characteristic and speed of change in ellipsoid height of the point - the point of the survey is a survey to the next, then the greater the reduction in soil characteristics and will be known. This paper mainly discusses the results obtained by GPS surveys that have been conducted in 2011, 2013, 2014 and2015. Land subsidence in Semarang until now still occur, especially in the northern region of Semarang. In the range of 2011-2015 land subsidence rates of 15 cm / year besides that for studying land subsidence in Demak, there was 10 Bench Mark was established.

Review: Regional land subsidence accompanying groundwater extraction

USGS Publications Warehouse

Galloway, Devin L.; Burbey, Thomas J.

2011-01-01

The extraction of groundwater can generate land subsidence by causing the compaction of susceptible aquifer systems, typically unconsolidated alluvial or basin-fill aquifer systems comprising aquifers and aquitards. Various ground-based and remotely sensed methods are used to measure and map subsidence. Many areas of subsidence caused by groundwater pumping have been identified and monitored, and corrective measures to slow or halt subsidence have been devised. Two principal means are used to mitigate subsidence caused by groundwater withdrawal—reduction of groundwater withdrawal, and artificial recharge. Analysis and simulation of aquifer-system compaction follow from the basic relations between head, stress, compressibility, and groundwater flow and are addressed primarily using two approaches—one based on conventional groundwater flow theory and one based on linear poroelasticity theory. Research and development to improve the assessment and analysis of aquifer-system compaction, the accompanying subsidence and potential ground ruptures are needed in the topic areas of the hydromechanical behavior of aquitards, the role of horizontal deformation, the application of differential synthetic aperture radar interferometry, and the regional-scale simulation of coupled groundwater flow and aquifer-system deformation to support resource management and hazard mitigation measures.

Pacific-North America plate boundary reorganization in response to a change in relative plate motion: Offshore Canada

NASA Astrophysics Data System (ADS)

Rohr, K. M. M.; Tryon, A. J.

2010-06-01

The transition from subduction in Cascadia to the transform Queen Charlotte fault along western Canada is often drawn as a subduction zone, yet recent studies of GPS and earthquake data from northern Vancouver Island are not consistent with that model. In this paper we synthesize seismic reflection and gravity interpretations with microseismicity data in order to test models of (1) microplate subduction and (2) reorganization of the preexisting strike-slip plate boundary. We focus on the critical region of outer Queen Charlotte Sound and the adjacent offshore. On much of the continental shelf, several million years of subsidence above thin crust are a counterindicator for subduction. An undated episode of compression uplifted the southernmost shelf, but subsidence patterns offshore show that recent subduction is unlikely to be responsible. Previously unremarked near-vertical faults and a mix of extensional and compressional faults offshore indicate that strike-slip faulting has been a significant mode of deformation. Seismicity in the last 18 years is dominantly strike-slip and shows large amounts of moment release on the Revere-Dellwood fault and its overlap with the Queen Charlotte fault. The relative plate motion between the Pacific and North American plates rotated clockwise ˜6 Ma and appears to have triggered formation of an evolving array of structures. We suggest that the paleo-Queen Charlotte fault which had defined this continental margin retreated northward as offshore distributed shear and the newly formed Revere Dellwood fault propagated to the northwest.

Coal mine subsidence: proceedings from a citizen's conference

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mavrolas, P.; Schechtman, M.

A lay summary of coal-mine subsidence presents non-technical information for people in Illinois' subsidence-prone areas, and describes state and national assistance programs. The report explains mining methods and the effects of subsidence on buildings and farmland. It tells what to do in the event of an emergency and how to buy a home in a questionable area. The five appendices include directories to state and federal agencies. 14 figures, 1 table. (DCK)

Cenozoic tectonic subsidence in the Southern Continental Margin, South China Sea

NASA Astrophysics Data System (ADS)

Fang, Penggao; Ding, Weiwei; Fang, Yinxia; Zhao, Zhongxian; Feng, Zhibing

2017-06-01

We analyzed two recently acquired multichannel seismic profiles across the Dangerous Grounds and the Reed Bank area in the South China Sea. Reconstruction of the tectonic subsidence shows that the southern continental margin can be divided into three stages with variable subsidence rate. A delay of tectonic subsidence existed in both areas after a break-up, which was likely related to the major mantle convection during seafloor spreading, that was triggered by the secondary mantle convection below the continental margin, in addition to the variation in lithospheric thickness. Meanwhile, the stage with delayed subsidence rate differed along strikes. In the Reed Bank area, this stage is between 32-23.8 Ma, while in the Dangerous Grounds, it was much later (between 19-15.5 Ma). We believe the propagated rifting in the South China Sea dominated the changes of this delayed subsidence rate stage.

Land subsidence caused by ground water withdrawal in urban areas

USGS Publications Warehouse

Holzer, T.L.; Johnson, A.I.

1985-01-01

At least eight urban areas in the world have encountered significant economic impact from land subsidence caused by pumping of ground water from unconsolidated sediment. The areas, most of which are coastal, include Bangkok, Houston, Mexico City, Osaka, San Jose, Shanghai, Tokyo, and Venice. Flooding related to decreased ground elevation is the principal adverse effect of the subsidence. Lesser effects include regional tilting, well-casing failures, "rising" buildings, and ground failure or rupture. Subsidence of most of these urban areas began before the phenomenon was discovered and understood. Thus, the subsidence problems were unanticipated. Methods to arrest subsidence typically have included control of ground water pumping and development of surface water to offset the reductions of ground water pumping. Ground water recharge has also been practiced. Areas threatened by flooding have been protected by extensive networks of dikes and sea walls, locks, and pumping stations to remove storm runoff. ?? 1985 D. Reidel Publishing Company.

High-resolution InSAR constraints on flood-related subsidence and evaporite dissolution along the Dead Sea shores: Interplay between hydrology and rheology

NASA Astrophysics Data System (ADS)

Shviro, Maayan; Haviv, Itai; Baer, Gidon

2017-09-01

Sinkhole generation and land subsidence are commonly attributed to dissolution of subsurface layers by under-saturated groundwater and formation of cavities. Along the Dead Sea (DS) shorelines, this process also involves seasonal flash floods that are drained into the subsurface by existing and newly formed sinkholes. We quantify the contribution of flash-floods to salt dissolution and land subsidence using high-resolution interferometric synthetic aperture radar (InSAR). Subsidence rates during a 3-year period (2012-2015) were calculated from 57 COSMO SkyMed X-band interferograms bracketing major flood events and intra-flood periods in 21 sinkhole sites. The sites are located within channels and alluvial fans along the western shores of the Dead Sea, Israel. The observed subsidence reaches maximum rates of 2.5 mm/day, accumulating in specific sites to 500 mm/year. In most of the sinkhole sites a gradual increase in the annual subsidence rate is observed during the 3-year study period. Three different modes of response to floods were observed: (1) sites where floodwater is not directly channeled into sinkholes do not respond to floods; (2) sites adjacent to active channels with sinkholes are unaffected by specific floods but their subsidence rates increase gradually from early winter to mid-summer, and decay gradually until the following winter; and (3) sites in active channels with sinkholes are characterized by an abrupt increase in subsidence rates immediately after each flood (by a factor of up to 20) and by a subsequent quasi-exponential subsidence decay over periods of several months. In these latter sites, subsidence rates after each flood are temporally correlated with alternating groundwater levels in adjacent boreholes. The rapid rise in groundwater head following floods increases the hydraulic gradient of the under-saturated groundwater and hence also the groundwater discharge and the dissolution rate of the subsurface salt layer. A subsequent quasi-exponential water level drop results in similar deceleration in dissolution and subsidence rates, with a similar characteristic decay time of about 150 days. The observed subsidence decay pattern may also be explained by viscoelastic relaxation of the overburden in response to instantaneously-formed dissolution cavities. Utilizing a Kelvin viscoelastic model, we show that the contribution of this process is most probably < 30% of the total observed subsidence and is sensitive to the sediment mechanical properties. On a broader scale, this study demonstrates how high-resolution InSAR measurements can improve our understanding of subsurface dissolution and subsidence processes and provide independent constraints on the mechanical properties of heterogeneous alluvial sediments.

Land subsidence, groundwater levels, and geology in the Coachella Valley, California, 1993-2010

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin T.; Solt, Mike

2014-01-01

Land subsidence associated with groundwater-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Groundwater has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of groundwater resulted in water-level declines as much as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in groundwater pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated groundwater-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and Interferometric Synthetic Aperture Radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley during 1993–2010. The GPS measurements taken at 11 geodetic monuments in 1996 and in 2010 in the southern Coachella Valley indicated that the elevation of the land surface changed –136 to –23 millimeters (mm) ±54 mm (–0.45 to –0.08 feet (ft) ±0.18 ft) during the 14-year period. Changes at 6 of the 11 monuments exceeded the maximum expected uncertainty of ±54 mm (±0.18 ft) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2010. GPS measurements taken at 17 geodetic monuments in 2005 and 2010 indicated that the elevation of the land surface changed –256 to +16 mm ±28 mm (–0.84 to +0.05 ft ±0.09 ft) during the 5-year period. Changes at 5 of the 17 monuments exceeded the maximum expected uncertainty of ±28 mm (±0.09 ft) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between August 2005 and August 2010. At each of these five monuments, subsidence rates were about the same between 2005 and 2010 as between 2000 and 2005. InSAR measurements taken between June 27, 1995, and September 19, 2010, indicated that the land surface subsided from about 220 to 600 mm (0.72 to 1.97 ft) in three areas of the Coachella Valley: near Palm Desert, Indian Wells, and La Quinta. In Palm Desert, the average subsidence rates increased from about 39 millimeters per year (mm/yr), or 0.13 foot per year (ft/yr), during 1995–2000 to about 45 mm/yr (0.15 ft/yr) during 2003–10. In Indian Wells, average subsidence rates for two subsidence maxima were fairly steady at about 34 and 26 mm/yr (0.11 and 0.09 ft/yr) during both periods; for the third maxima, average subsidence rates increased from about 14 to 19 mm/yr (0.05 to 0.06 ft/yr) from the first to the second period. In La Quinta, average subsidence rates for five selected locations ranged from about 17 to 37 mm/yr (0.06 to 0.12 ft/yr) during 1995–2000; three of the locations had similar rates during 2003–mid-2009, while the other two locations had increased subsidence rates. Decreased subsidence rates were calculated throughout the La Quinta subsidence area during mid-2009–10, however, and uplift was observed during 2010 near the southern extent of this area. Water-level measurements taken at wells near the subsiding monuments and in the three subsiding areas shown by InSAR generally indicated that the water levels fluctuated seasonally and declined annually from the early 1990s, or earlier, to 2010; some water levels in 2010 were at the lowest levels in their recorded histories. An exception to annually declining water levels in and near subsiding areas was observed beginning in mid-2009 in the La Quinta subsidence area, where recovering water levels coincided with increased recharge operations at the Thomas E. Levy Recharge Facility; decreased pumpage also could cause groundwater levels to recover. Subsidence concomitant with declining water levels and land-surface uplift concomitant with recovering water levels indicate that aquifer-system compaction could be causing subsidence. If the stresses imposed by the historically lowest water levels exceeded the preconsolidation stress, the aquifer-system compaction and associated land subsidence could be permanent.

Vertical deformation associated with normal fault systems evolved over coseismic, postseismic, and multiseismic periods

USGS Publications Warehouse

Thompson, George A.; Parsons, Thomas E.

2016-01-01

Vertical deformation of extensional provinces varies significantly and in seemingly contradictory ways. Sparse but robust geodetic, seismic, and geologic observations in the Basin and Range province of the western United States indicate that immediately after an earthquake, vertical change primarily occurs as subsidence of the normal fault hanging wall. A few decades later, a ±100 km wide zone is symmetrically uplifted. The preserved topography of long-term rifting shows bent and tilted footwall flanks rising high above deep basins. We develop finite element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. We replicate observations with a model that has a weak upper mantle overlain by a stronger lower crust and a breakable elastic upper crust. A 60° dipping normal fault cuts through the upper crust and extends through the lower crust to simulate an underlying shear zone. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift under the footwall; the breakable upper crust is a necessary model feature to replicate footwall bending over the observed width ( < 10 km), which is predicted to take place within 1-2 decades after each large earthquake. Thus the best-preserved topographic signature of rifting is expected to occur early in the postseismic period. The relatively stronger lower crust in our models is necessary to replicate broader postseismic uplift that is observed geodetically in subsequent decades.

Evolving phenotypic networks in silico.

PubMed

François, Paul

2014-11-01

Evolved gene networks are constrained by natural selection. Their structures and functions are consequently far from being random, as exemplified by the multiple instances of parallel/convergent evolution. One can thus ask if features of actual gene networks can be recovered from evolutionary first principles. I review a method for in silico evolution of small models of gene networks aiming at performing predefined biological functions. I summarize the current implementation of the algorithm, insisting on the construction of a proper "fitness" function. I illustrate the approach on three examples: biochemical adaptation, ligand discrimination and vertebrate segmentation (somitogenesis). While the structure of the evolved networks is variable, dynamics of our evolved networks are usually constrained and present many similar features to actual gene networks, including properties that were not explicitly selected for. In silico evolution can thus be used to predict biological behaviours without a detailed knowledge of the mapping between genotype and phenotype. Copyright © 2014 The Author. Published by Elsevier Ltd.. All rights reserved.

A new powerful parameterization tool for managing groundwater resources and predicting land subsidence in Las Vegas Valley

NASA Astrophysics Data System (ADS)

Zhang, M.; Nunes, V. D.; Burbey, T. J.; Borggaard, J.

2012-12-01

More than 1.5 m of subsidence has been observed in Las Vegas Valley since 1935 as a result of groundwater pumping that commenced in 1905 (Bell, 2002). The compaction of the aquifer system has led to several large subsidence bowls and deleterious earth fissures. The highly heterogeneous aquifer system with its variably thick interbeds makes predicting the magnitude and location of subsidence extremely difficult. Several numerical groundwater flow models of the Las Vegas basin have been previously developed; however none of them have been able to accurately simulate the observed subsidence patterns or magnitudes because of inadequate parameterization. To better manage groundwater resources and predict future subsidence we have updated and developed a more accurate groundwater management model for Las Vegas Valley by developing a new adjoint parameter estimation package (APE) that is used in conjunction with UCODE along with MODFLOW and the SUB (subsidence) and HFB (horizontal flow barrier) packages. The APE package is used with UCODE to automatically identify suitable parameter zonations and inversely calculate parameter values from hydraulic head and subsidence measurements, which are highly sensitive to both elastic (Ske) and inelastic (Skv) storage coefficients. With the advent of InSAR (Interferometric synthetic aperture radar), distributed spatial and temporal subsidence measurements can be obtained, which greatly enhance the accuracy of parameter estimation. This automation process can remove user bias and provide a far more accurate and robust parameter zonation distribution. The outcome of this work yields a more accurate and powerful tool for managing groundwater resources in Las Vegas Valley to date.

Quantification of groundwater extraction-induced subsidence in the Mekong delta, Vietnam: 3D process-based numerical modeling

NASA Astrophysics Data System (ADS)

Minderhoud, Philip S. J.; Erkens, Gilles; Pham, Hung V.; Bui, Vuong T.; Kooi, Henk; Erban, Laura; Stouthamer, Esther

2017-04-01

The demand for groundwater in the Vietnamese Mekong delta has steadily risen over the past decades. As a result, hydraulic heads in the aquifers dropped on average 0.3-0.7 m/yr-1, potentially causing aquifer-system compaction. At present, the delta is experiencing subsidence rates up to several centimeters per year that outpace global sea level rise by an order of magnitude. However, the exact contribution of groundwater extraction to total subsidence in the delta has not been assessed yet. The objective of our study is to quantify the impact of 25 years of groundwater extraction on subsidence. We built a 3D numerical hydrogeological model comprising the multi-aquifer system of the entire Vietnamese Mekong delta. Groundwater dynamics in the aquifers was simulated over the past quarter-century based on the known extraction history and measured time series of hydraulic head. Subsequently, we calculated corresponding aquifer system compaction using a coupled land subsidence module, which includes a direct, elastic component and a secular, viscous component (i.e. creep). The hydrogeological model is able to reproduce the measured drawdowns in the multi-aquifer system of the past 25 years. Corresponding subsidence rates resulting from aquifer system compaction show a gradual increase over the past two decades to significant annual rates up to several centimeters. Groundwater extraction seems to be a dominant driver of subsidence in the delta, but does not explain the total measured subsidence. This process-based modeling approach can be used to quantify groundwater extraction-induced subsidence for coastal areas and at delta-scale worldwide.

Holocene subsidence at the transition between strike-slip and subduction on the Pacific-Australian plate boundary, Marlborough Sounds, New Zealand

NASA Astrophysics Data System (ADS)

Hayward, Bruce W.; Grenfell, Hugh R.; Sabaa, Ashwaq T.; Kay, Jon; Daymond-King, Rhiannon; Cochran, Ursula

2010-03-01

This paper provides the first solid evidence in support of a century-old hypothesis that the mountainous Marlborough Sounds region in central New Zealand is subsiding. More recent hypotheses suggest that this may be a result of southward migration of a slab of subducted Pacific Plate causing flexural downwarping of the overlying crust in the vicinity of the transition between subduction and strike-slip on the Pacific-Australian plate boundary. The proxy evidence for gradual Holocene subsidence comes from micropaleontological study of seven intertidal sediment cores from the inner Marlborough Sounds (at Havelock, Mahau Sound and Shakespeare Bay). Quantitative estimates (using Modern Analogue Technique) of former tidal elevations based on fossil foraminiferal faunas provide evidence of tectonic (not compaction-related) subsidence in all cores. Estimates of subsidence rates for individual cores vary within the range 0.2-2.4 m ka -1. The wide variation within subsidence rate estimates are related to a combination of the accuracy limits of radiocarbon dates, elevation estimates, and particularly our poor knowledge of the New Zealand Holocene sea-level curve. The most consistent subsidence rate at all three sites for the mid-late Holocene (last 6-7 ka) is ˜0.7-0.8 m ka -1. This rate is consistent with the average subsidence rate in the adjacent 4-km thick Wanganui sedimentary basin for the last 5 myr. Subsidence is inferred to have migrated southwards from the Wanganui Basin to impinge on the inner Marlborough Sounds in just the last 100-200 ka.

Land subsidence monitoring in central Taiwan by using PS-InSAR technique

NASA Astrophysics Data System (ADS)

Hu, J.-C.; Tung, H.; Huang, M.-H.

2009-04-01

Ground subsidence induced by heavy withdrawal of underground water has resulted in environmental hazard and potential risk in Taiwan, particularly in the Choushui River alluvial fan where the Yunlin section of the Taiwan High Speed Rail had been constructed. The Yunlin County located in the southwestern coastal region of Taiwan is one of the most counties with serious land subsidence because of the agricultural needs. Yunlin County is one of the important agricultural production regions located in the southwestern coastal region of Taiwan where the irrigated area is up to 123,000 hectares and agricultural water consumption reaches approximate 90 percents of all available water resources in the Choshui River Basin. Moreover, since there is no sufficient surface water supplied, groundwater becomes a vital resource for every water consumption targets. Seasonal effects of land subsidence occurring in the study area had been estimated using a regression analysis of a series of weekly GPS height solutions. These results demonstrated the average rate of ground subsidence in this area over the period of 1995-2001 was 3 cm/yr. Based on data collected at the piezometer, the variation of land subsidence rate appears to be associated with an unstable underground water level, which drop gradually during winter and either remains constant or rises during summer time. Consequently, land subsidence rates vary considerably from 1.5 cm/yr for the summer time to 9.0 cm/yr for the winter time. In addition, anthropogenic ground subsidence due to massive pumping of groundwater is one of problems in Taiwan. In this study, we represented a both stacking D-InSAR and PS-InSAR results deduced from 1996-1999 time spans for monitoring of land subsidence in this area. Both D-InSAR and PS-InSAR results show the Baojhou, Tuku Township and northern Mailiao reveal a maximum subsidence rate of about 6 cm/yr along LOS and the Taishi Township located on the coastal area reveals a subsidence rate of 1.6 cm/yr, which is quite coincident with precise leveling result. These two results have proven that the effective reduction of labor and cost could be achieved by using this technique on monitoring land subsidence in Yunlin County.

Numerical Modeling of Pot-Hole Subsidence Due to Shallow Underground Coal Mining in Structurally Disturbed Ground

NASA Astrophysics Data System (ADS)

Lokhande, Ritesh D.; Murthy, V. M. S. R.; Singh, K. B.; Verma, Chandan Prasad; Verma, A. K.

2018-04-01

Stability analysis of underground mining is, generally, complex in nature and is difficult to carry out through analytical solutions more so in case of pot-hole subsidence prediction. Thus, application of numerical modeling technique for simulating and finding a solution is preferred. This paper reports the development of a methodology for simulating the pot-hole subsidence using FLAC3D. This study is restricted to geologically disturbed areas where presence of fault was dominating factor for occurrence of pot-hole subsidence. The results demonstrate that the variation in the excavation geometry and properties of immediate roof rocks play a vital role in the occurrence of pot-hole subsidence.

Shatter Complex Formation in the Twin Craters Lava Flow, Zuni-Bandera Field, New Mexico

NASA Astrophysics Data System (ADS)

von Meerscheidt, H. C.; Bleacher, J. E.; Brand, B. D.; deWet, A.; Samuels, R.; Hamilton, C.; Garry, W. B.; Bandfield, J. L.

2013-12-01

Lava channels, tubes and sheets are transport structures that deliver flowing lava to a flow front. The type of structure can vary within a flow field and evolve throughout an eruption. The 18.0 × 1.0 ka Twin Craters lava flow in the Zuni-Bandera lava field provides a unique opportunity to study morphological changes of a lava flow partly attributable to interaction with a topographic obstacle. Facies mapping and airborne image analysis were performed on an area of the Twin Craters flow that includes a network of channels, lava tubes, shatter features, and disrupted pahoehoe flows surrounding a 45 m tall limestone bluff. The bluff is 1000 m long (oriented perpendicular to flow.) The general flow characteristics upstream from the bluff include smooth, lobate pahoehoe flows and a >2.5 km long lava tube (see Samuels et al., this meeting.) Emplacement characteristics change abruptly where the flow encountered the bluff, to include many localized areas of disrupted pahoehoe and several pahoehoe-floored depressions. Each depression is fully or partly surrounded by a raised rim of blocky material up to 4 m higher than the surrounding terrain. The rim is composed of 0.05 - 4 m diameter blocks, some of which form a breccia that is welded by lava, and some of which exhibit original flow textures. The rim-depression features are interpreted as shatter rings based on morphological similarity to those described by Orr (2011.Bul Volcanol.73.335-346) in Hawai';i. Orr suggests that shatter rings develop when fluctuations in the lava supply rate over-pressurize the tube, causing the tube roof to repeatedly uplift and subside. A rim of shattered blocks and breccias remains surrounding the sunken tube roof after the final lava withdraws from the system. One of these depressions in the Twin Craters flow is 240 m wide and includes six mounds of shattered material equal in height to the surrounding undisturbed terrain. Several mounds have depressed centers floored with rubbly pahoehoe. Prominent ';a';a channels travel around the bluff, leaving a 'wake' of uncovered ground on the downstream side. We interpret this shatter area to have been a branching tube network within an active sheet. The limestone bluff acted as an obstacle that caused a backup of lava within the tubes, driving episodes of shattering. The mounds likely represent earlier solidified sections between active, possibly braided, tube branches, which remained as mounds within the shatter area after the adjacent crust subsided. When lava broke out from the pressurized sheet-like lobe, it formed the ';a';a channels. This section of the flow field is interpreted using inferences from shatter ring formation, but is perhaps better termed a shatter sheet or shatter complex. This study has implications for understanding lava flow dynamics at constriction points, as well as the evolution and morphology of shatter rings.

Subsidence from underground mining; environmental analysis and planning considerations

USGS Publications Warehouse

Lee, Fitzhugh T.; Abel, John F.

1983-01-01

Subsidence, a universal process that occurs in response to the voids created by extracting solids or liquids from beneath the Earth's surface, is controlled by many factors including mining methods, depth of extraction, thickness of deposit, and topography, as well as the in situ properties of the rock mass above the deposit. The impacts of subsidence are potentially severe in terms of damage to surface utility lines and structures, changes in surface-water and ground-water conditions, and effects on vegetation and animals. Although subsidence cannot be eliminated, it can be reduced or controlled in areas where deformation of the ground surface would produce dangerous or costly effects. Subsidence prediction is highly developed in Europe where there are comparatively uniform mining conditions and a long history of field measurements. Much of this mining has been carried out beneath crowded urban and industrial areas where accurate predictions have facilitated use of the surface and reduced undesirable impacts. Concerted efforts to understand subsidence processes in the United States are recent. Empirical methods of subsidence analysis and prediction based on local conditions seem better suited to the current state of knowledge of the varied geologic and topographic conditions in domestic coal mining regions than do theoretical/mathematical approaches. In order to develop broadly applicable subsidence prediction methods and models for the United States, more information is needed on magnitude and timing of ground movements and geologic properties.

Land Subsidence International Symposium held in Venice

NASA Astrophysics Data System (ADS)

The Third International Symposium on Land Subsidence was held March 18-25, 1984, in Venice, Italy. Sponsors were the Ground-Water Commission of the International Association of Hydrological Sciences (IAHS), the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the Italian National Research Council (CNR), the Italian Regions of Veneto and Emilia-Romagna, the Italian Municipalities of Venice, Ravenna, and Modena, the Venice Province, and the European Research Office. Cosponsors included the International Association of Hydrogeologists (IAH), the International Society for Soil Mechanics and Foundation Engineering (ISSMFE), and the Association of Geoscientists for International Development (AGID).Organized within the framework of UNESCO's International Hydrological Program, the symposium brought together over 200 international interdisciplinary specialists in the problems of land subsidence due to fluid and mineral withdrawal. Because man's continuing heavy development of groundwater, gas, oil, and minerals is changing the natural regime and thus causing more and more subsiding areas in the world, there had been sufficient new land subsidence occurrence, problems, research, and remedial measures since the 1976 Second International Symposium held in Anaheim, California, to develop a most interesting program of nearly 100 papers from about 30 countries. The program consisted of papers covering case histories of fluid and mineral withdrawal, engineering theory and analysis, karst “sink-hole”-type subsidence, subsidence due to dewatering of organic deposits or due to application of water (hydrocompaction), instrumentation, legal, socioeconomic, and environmental effects of land subsidence, and remedial works.

BasinVis 1.0: A MATLAB®-based program for sedimentary basin subsidence analysis and visualization

NASA Astrophysics Data System (ADS)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2016-06-01

Stratigraphic and structural mapping is important to understand the internal structure of sedimentary basins. Subsidence analysis provides significant insights for basin evolution. We designed a new software package to process and visualize stratigraphic setting and subsidence evolution of sedimentary basins from well data. BasinVis 1.0 is implemented in MATLAB®, a multi-paradigm numerical computing environment, and employs two numerical methods: interpolation and subsidence analysis. Five different interpolation methods (linear, natural, cubic spline, Kriging, and thin-plate spline) are provided in this program for surface modeling. The subsidence analysis consists of decompaction and backstripping techniques. BasinVis 1.0 incorporates five main processing steps; (1) setup (study area and stratigraphic units), (2) loading well data, (3) stratigraphic setting visualization, (4) subsidence parameter input, and (5) subsidence analysis and visualization. For in-depth analysis, our software provides cross-section and dip-slip fault backstripping tools. The graphical user interface guides users through the workflow and provides tools to analyze and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the results using the full range of available plot options in MATLAB. We demonstrate all functions in a case study of Miocene sediment in the central Vienna Basin.

Effect of external digital elevation model on monitoring of mine subsidence by two-pass differential interferometric synthetic aperture radar

NASA Astrophysics Data System (ADS)

Tao, Qiuxiang; Gao, Tengfei; Liu, Guolin; Wang, Zhiwei

2017-04-01

The external digital elevation model (DEM) error is one of the main factors that affect the accuracy of mine subsidence monitored by two-pass differential interferometric synthetic aperture radar (DInSAR), which has been widely used in monitoring mining-induced subsidence. The theoretical relationship between external DEM error and monitored deformation error is derived based on the principles of interferometric synthetic aperture radar (DInSAR) and two-pass DInSAR. Taking the Dongtan and Yangcun mine areas of Jining as test areas, the difference and accuracy of 1:50000, ASTER GDEM V2, and SRTM DEMs are compared and analyzed. Two interferometric pairs of Advanced Land Observing Satellite Phased Array L-band SAR covering the test areas are processed using two-pass DInSAR with three external DEMs to compare and analyze the effect of three external DEMs on monitored mine subsidence in high- and low-coherence subsidence regions. Moreover, the reliability and accuracy of the three DInSAR-monitored results are compared and verified with leveling-measured subsidence values. Results show that the effect of external DEM on mine subsidence monitored by two-pass DInSAR is not only related to radar look angle, perpendicular baseline, slant range, and external DEM error, but also to the ground resolution of DEM, the magnitude of subsidence, and the coherence of test areas.

Evaluation of subsidence hazard in mantled karst setting: a case study from Val d'Orléans (France)

NASA Astrophysics Data System (ADS)

Perrin, Jérôme; Cartannaz, Charles; Noury, Gildas; Vanoudheusden, Emilie

2015-04-01

Soil subsidence/collapse is a major geohazard occurring in karst region. It occurs as suffosion or dropout sinkholes developing in the soft cover. Less frequently it corresponds to a breakdown of karst void ceiling (i.e., collapse sinkhole). This hazard can cause significant engineering challenges. Therefore decision-makers require the elaboration of methodologies for reliable predictions of such hazards (e.g., karst subsidence susceptibility and hazards maps, early-warning monitoring systems). A methodological framework was developed to evaluate relevant conditioning factors favouring subsidence (Perrin et al. submitted) and then to combine these factors to produce karst subsidence susceptibility maps. This approach was applied to a mantled karst area south of Paris (Val d'Orléans). Results show the significant roles of the overburden lithology (presence/absence of low-permeability layer) and of the karst aquifer piezometric surface position within the overburden. In parallel, an experimental site has been setup to improve the understanding of key processes leading to subsidence/collapse and includes piezometers for measurements of water levels and physico-chemical parameters in both the alluvial and karst aquifers as well as surface deformation monitoring. Results should help in designing monitoring systems to anticipate occurrence of subsidence/collapse. Perrin J., Cartannaz C., Noury G., Vanoudheusden E. 2015. A multicriteria approach to karst subsidence hazard mapping supported by Weights-of-Evidence analysis. Submitted to Engineering Geology.

Detecting Subsidence Along a High Speed Railway by Ultrashort Baseline TCP-InSAR with High Resolution Images

NASA Astrophysics Data System (ADS)

Dai, K. R.; Liu, G. X.; Yu, B.; Jia, H. G.; Ma, D. Y.; Wang, X. W.

2013-10-01

A High Speed Railway goes across Wuqing district of Tianjin, China. Historical studies showed that the land subsidence of this area was very serious, which would give rise to huge security risk to the high speed railway. For detecting the detailed subsidence related to the high speed railway, we use the multi-temporal InSAR (MT-InSAR) technique to extract regional scale subsidence of Wuqing district. Take it into consideration that Wuqing district is a suburban region with large area of low coherence farmland, we select the temporarily coherent point InSAR (TCP-InSAR) approach for MT-InSAR analysis. The TCP-InSAR is a potential approach for detecting land subsidence in low coherence areas as it can identify and analysis coherent points between just two images and can acquire a reliable solution without conventional phase unwrapping. This paper extended the TCP-InSAR with use of ultrashort spatial baseline (USB) interferograms. As thetopographic effects are negligible in the USB interferograms, an external digital elevation model (DEM) is no longer needed in interferometric processing, and the parameters needed to be estimated were simplified at the same time. With use of 17 TerraSAR-X (TSX) images acquired from 2009 to 2010 over Wuqing district, the annual subsidence rates along the high speed railway were derived by the USB-TCPInSAR approach. Two subsidence funnels were found at ShuangJie town and around Wuqing Station with subsidence rate of -17 ∼ -27 mm/year and -7 ∼ -17 mm/year, respectively. The subsidence rates derived by USB-TCPInSAR were compared with those derived by the conventional TCP-InSAR that uses an external DEM for differential interferometry. The mean and the standard deviation of the differences between two types of results at 370697 TCPs are -4.43 × 10-6 mm/year and ±1.4673 mm/year, respectively. Further comparison with the subsidence results mentioned in several other studies were made, which shows good consistencies. The results verify that even without using a DEM the USB-TCPInSAR method can detect land subsidence accurately in flat areas.

Monitoring Subsidence in California with InSAR

NASA Astrophysics Data System (ADS)

Farr, T. G.; Jones, C. E.; Liu, Z.; Neff, K. L.; Gurrola, E. M.; Manipon, G.

2016-12-01

Subsidence caused by groundwater pumping in the rich agricultural area of California's Central Valley has been a problem for decades. Over the last few years, interferometric synthetic aperture radar (InSAR) observations from satellite and aircraft platforms have been used to produce maps of subsidence with cm accuracy. We are continuing work reported previously, using ESA's Sentinel-1 to extend our maps of subsidence in time and space, in order to eventually cover all of California. The amount of data to be processed has expanded exponentially in the course of our work and we are now transitioning to the use of the ARIA project at JPL to produce the time series. ARIA processing employs large Amazon cloud instances to process single or multiple frames each, scaling from one to many (20+) instances working in parallel to meet the demand (700 GB InSAR products within 3 hours). The data are stored in Amazon long-term storage and an http view of the products are available for users of the ARIA system to download the products. Higher resolution InSAR data were also acquired along the California Aqueduct by the NASA UAVSAR from 2013 - 2016. Using multiple scenes acquired by these systems, we are able to produce time series of subsidence at selected locations and transects showing how subsidence varies both spatially and temporally. The maps show that subsidence is continuing in areas with a history of subsidence and that the rates and areas affected have increased due to increased groundwater extraction during the extended western US drought. Our maps also identify and quantify new, localized areas of accelerated subsidence. The California Department of Water Resources (DWR) funded this work to provide the background and an update on subsidence in the Central Valley to support future policy. Geographic Information System (GIS) files are being furnished to DWR for further analysis of the 4 dimensional subsidence time-series maps. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

A MATLAB®-based program for 3D visualization of stratigraphic setting and subsidence evolution of sedimentary basins: example application to the Vienna Basin

NASA Astrophysics Data System (ADS)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2015-04-01

In recent years, 3D visualization of sedimentary basins has become increasingly popular. Stratigraphic and structural mapping is highly important to understand the internal setting of sedimentary basins. And subsequent subsidence analysis provides significant insights for basin evolution. This study focused on developing a simple and user-friendly program which allows geologists to analyze and model sedimentary basin data. The developed program is aimed at stratigraphic and subsidence modelling of sedimentary basins from wells or stratigraphic profile data. This program is mainly based on two numerical methods; surface interpolation and subsidence analysis. For surface visualization four different interpolation techniques (Linear, Natural, Cubic Spline, and Thin-Plate Spline) are provided in this program. The subsidence analysis consists of decompaction and backstripping techniques. The numerical methods are computed in MATLAB® which is a multi-paradigm numerical computing environment used extensively in academic, research, and industrial fields. This program consists of five main processing steps; 1) setup (study area and stratigraphic units), 2) loading of well data, 3) stratigraphic modelling (depth distribution and isopach plots), 4) subsidence parameter input, and 5) subsidence modelling (subsided depth and subsidence rate plots). The graphical user interface intuitively guides users through all process stages and provides tools to analyse and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the visualization results using the full range of available plot options in MATLAB. All functions of this program are illustrated with a case study of Miocene sediments in the Vienna Basin. The basin is an ideal place to test this program, because sufficient data is available to analyse and model stratigraphic setting and subsidence evolution of the basin. The study area covers approximately 1200 km2 including 110 data points in the central part of the Vienna Basin.

Development of an expert analysis tool based on an interactive subsidence hazard map for urban land use in the city of Celaya, Mexico

NASA Astrophysics Data System (ADS)

Alloy, A.; Gonzalez Dominguez, F.; Nila Fonseca, A. L.; Ruangsirikulchai, A.; Gentle, J. N., Jr.; Cabral, E.; Pierce, S. A.

2016-12-01

Land Subsidence as a result of groundwater extraction in central Mexico's larger urban centers initiated in the 80's as a result of population and economic growth. The city of Celaya has undergone subsidence for a few decades and a consequence is the development of an active normal fault system that affects its urban infrastructure and residential areas. To facilitate its analysis and a land use decision-making process we created an online interactive map enabling users to easily obtain information associated with land subsidence. Geological and socioeconomic data of the city was collected, including fault location, population data, and other important infrastructure and structural data has been obtained from fieldwork as part of a study abroad interchange undergraduate course. The subsidence and associated faulting hazard map was created using an InSAR derived subsidence velocity map and population data from INEGI to identify hazard zones using a subsidence gradient spatial analysis approach based on a subsidence gradient and population risk matrix. This interactive map provides a simple perspective of different vulnerable urban elements. As an accessible visualization tool, it will enhance communication between scientific and socio-economic disciplines. Our project also lays the groundwork for a future expert analysis system with an open source and easily accessible Python coded, SQLite database driven website which archives fault and subsidence data along with visual damage documentation to civil structures. This database takes field notes and provides an entry form for uniform datasets, which are used to generate a JSON. Such a database is useful because it allows geoscientists to have a centralized repository and access to their observations over time. Because of the widespread presence of the subsidence phenomena throughout cities in central Mexico, the spatial analysis has been automated using the open source software R. Raster, rgeos, shapefiles, and rgdal libraries have been used to develop the script which permits to obtain the raster maps of horizontal gradient and population density. An advantage is that this analysis can be automated for periodic updates or repurposed for similar analysis in other cities, providing an easily accessible tool for land subsidence hazard assessments.

A preliminary assessment of land-surface subsidence in the El Paso area, Texas

USGS Publications Warehouse

Land, L.F.; Armstrong, C.A.

1985-01-01

In addition to regional subsidence, local subsidence is indicated by observable surface fractures but has not been verified by precise leveling. These local areas coincide with areas that historically were swamps along the Rio Grande.

Characterization of the Marine Boundary Layer and the Trade-Wind Inversion over the Sub-tropical North Atlantic

NASA Astrophysics Data System (ADS)

Carrillo, J.; Guerra, J. C.; Cuevas, E.; Barrancos, J.

2016-02-01

The stability of the lower troposphere along the east side of the sub-tropical North Atlantic is analyzed and characterized using upper air meteorological long-term records at the Canary Islands (Tenerife), Madeira (Madeira) and Azores (Terceira) archipelagos. The most remarkable characteristic is the strong stratification observed in the lower troposphere, with a strengthening of stability centred at levels near 900 and 800 hPa in a significant percentage of soundings (ranging from 17 % in Azores to 33 % in Güimar, Canary Islands). We show that this double structure is associated with the top of the marine boundary layer (MBL) and the trade-wind inversion (TWI) respectively. The top of the MBL coincides with the base of the first temperature inversion (≈ 900 hPa) where a sharp change in water vapour mixing ratio is observed. A second temperature inversion is found near 800 hPa, which is characterized by a large directional wind shear just above the inversion layer, tied to the TWI. We find that seasonal and latitudinal variations of the height and strength of both temperature inversions are driven by large-scale subsiding air from the upper troposphere associated with the descent branch of the Hadley cell. Increased general subsidence in summertime enhances stability in the lower troposphere, more markedly in the southern stations, where the inversion-layer heights are found at lower levels enhancing the main features of these two temperature inversions. A simple conceptual model that explains the lower tropospheric inversion enhancement by subsidence is proposed.

Geology and evolution of the Northern Kara Sea Shelf

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradov, A.

1991-08-01

The interpretation of regional multichannel seismic reflection profiles collected during 1988-1987 yields the following features of the geology of the Northern Kara Sea Shelf (NKSS). Two regional deep sedimentary basins are clearly distinguished within the NKSS. They have rather complex inner structures and contain sediments 14.0-16.0 km thick. The basin are separated from each other by a relatively narrow, linear zone of basement high which extends from Uedineniya Island on the south to Vize Island on the north, where basement depth is 1.5-4.0 km. The sedimentary sections of the basins are composed of four lithological-stratigraphical sequences separated by unconformities whichmore » correlate well with regional unconformities in adjacent land areas. The initial stages of sedimentary basin development within the NKSS date back to the late Riphean-Vendian; probably they were associated with intracontinental rifting, when up to 4 km of sediments were deposited. During the most of the Phanerozoic, regional subsidence dominated; however, the rates of subsidence were different in the western and in the eastern basins, and varied in time for each basin. The subsidence was interrupted for relatively short periods when the region was affected by uplifts and erosion which resulted in formation of regional unconformities. The seismic data gave no evidence of Caledonian or any other Phanerozoic folding within the NKSS, which is in contrast with widespread assumptions. The results show that the geological structure and evolution of the NKSS differ greatly from those of adjacent Barents and Southern Kara Sea shelves.« less

Adaptive Management of Land Subsidence and Ground Fissuring in the Chino Groundwater Basin, California

NASA Astrophysics Data System (ADS)

Malone, A.; Rolfe, T.; Wildermuth, M.; Kavounas, P.

2014-12-01

The Chino Basin, located in southern California, is a large alluvial groundwater basin with storage in excess of five million acre-feet. The basin has a long history of groundwater development for various uses dating back to the early 1900s. As a result, piezometric heads declined basin-wide during the past century - in some areas by more than 200 feet. Declines of this magnitude typically cause irreversible aquifer-system compaction, which in turn results in subsidence at the ground surface. In portions of Chino Basin, land subsidence has been differential and accompanied by ground fissuring, which damaged existing infrastructure and poses concerns for new and existing development.Chino Basin Watermaster, the agency responsible for groundwater basin management, has recognized that land subsidence and ground fissuring should be minimized to the extent possible. At the same time, Watermaster is implementing aggressive groundwater-supply programs that include controlled overdraft and the possibility of causing head declines in areas prone to subsidence and fissuring. The groundwater-supply programs must also address the subsidence and fissuring phenomena.From 2001 to 2005, Watermaster conducted a technical investigation to characterize the extent, rate, and mechanisms of subsidence and fissuring. The investigation employed InSAR and ground-level surveying of benchmarks to monitor ground-surface deformation, and borehole extensometers and piezometric monitoring to establish the relationships between groundwater production, piezometric levels, and aquifer-system deformation. Based on the results of the investigation, Watermaster developed: (i) subsidence-management criteria for the areas experiencing acute subsidence and fissuring, and (ii) an adaptive management program to minimize the potential for future subsidence and fissuring across the entire Chino Basin. The science-based program includes ongoing monitoring, which now includes sophisticated fissure-monitoring techniques, data analysis, annual reporting, and adjustment to the program as warranted by the data.

Data Acquisition for Land Subsidence Control

NASA Astrophysics Data System (ADS)

Zhu, Y.; Balke, K.

2009-12-01

For controlling land subsidence caused by groundwater over-exploitation, loading of engineered structures, mining and other anthropogenic activities in this fast changing world, a large variety of different data of various scales of concerning areas are needed for scientific study and administrative operational purposes. The economical, social and environmental impacts of anthropogenic land subsidence have long been recognized by many scientific institutions and management authorities based on results of monitoring and analysis at an interdisciplinary level. The land subsidence information systems composed of the surface and subsurface monitoring nets (monitoring and development wells, GPS stations and other facilities) and local data processing centers as a system management tool in Shanghai City was started with the use of GPS technology to monitor land subsidence in 1998. After years of experiences with a set of initiatives by adopting adequate countermeasures, the particular attention given to new improved methodologies to monitor and model the process of land subsidence in a simple and timely way, this is going to be promoted in the whole Yangtze River Delta region in China, where land subsidence expands in the entire region of urban cluster. The Delta land subsidence monitoring network construction aims to establish an efficient and coordinated water resource management system. The land subsidence monitoring network records "living history" of land subsidence, produces detailed scheduled reports and environmental impact statements. For the different areas with local factors and site characteristics, parallel packages need to be designed for predicting changes, land sensitivity and uncertainty analysis, especially for the risk analysis in the rapid growth of megacities and urban areas. In such cases, the new models with new types of local data and the new ways of data acquisition provide the best information for the decision makers for their mitigating decisions. The problems with outputs to professional and non-professional users, planning vs exploitation conflicts, 3D modeling and visualization are not yet solved due to the complex issues.

Understanding Mississippi Delta Subsidence through Stratigraphic and Geotechnical Analysis of a Continuous Holocene Core at a Subsidence Superstation

NASA Astrophysics Data System (ADS)

Bridgeman, J.; Tornqvist, T. E.; Allison, M. A.; Jafari, N.

2016-12-01

Land-surface subsidence is a major contributor to recent Mississippi Delta land loss. Despite significant research efforts, the primary mechanisms and rates of delta subsidence remain the subject of debate. This has led to a broad range of subsidence rate estimates across the delta, making differentiating between subsidence mechanisms as well as coastal restoration efforts more challenging. New data from a continuous 39 m long, 12 cm diameter core taken during the installation of a subsidence monitoring superstation near the Mississippi River, SW of New Orleans, provides insight into the grain size, bulk density, geochronology, and geotechnical parameters of the entire Holocene succession. The core consists of three major sections. The top 11 m contain a modern marsh peat, followed by a silty clay loam with interspersed humic clays (14C age 1250 BP), a peat bed (14C age 2200-2950 BP), and silt loams. The middle section from 11 to 35 m is dominated by clay and silty clay, with a relative bulk density of 1.5 g/cc, which gradually becomes denser with depth and the bottom section (35 to 39 m) is marked by a high energy, shell-rich sand facies and a basal peat (14C age 9850 BP), which terminates at the core base in a densely packed, blue-gray silty clay loam, characteristic of the Pleistocene. The radiocarbon ages of marsh peat beds, combined with sea-level markers derived from basal peat elsewhere in the delta, enable the reconstruction of the local subsidence history at this site. Notably, the data shows a significant amount of vertical displacement from the dated organics in the top section of the core; 3.5 m in the humic clays and up to 5 m in the peat bed. The subsidence rates measured by the superstation apparatus, and the geotechnical measurements of core sediments, will aid in determining the dominant subsidence mechanisms (shallow vs. deep) in the region.

Quantifying monthly to decadal subsidence and assessing collapse potential near the Wink sinkholes, west Texas, using airborne lidar, radar interferometry, and microgravity

NASA Astrophysics Data System (ADS)

Paine, J. G.; Collins, E.; Yang, D.; Andrews, J. R.; Averett, A.; Caudle, T.; Saylam, K.

2014-12-01

We are using airborne lidar and satellite-based radar interferometry (InSAR) to quantify short-term (months to years) and longer-term (decades) subsidence in the area surrounding two large (100- to 200-m diameter) sinkholes that formed above Permian bedded salt in 1980 and 2002 in the Wink area, west Texas. Radar interferograms constructed from synthetic aperture radar data acquired between 2008 and 2011 with the ALOS PALSAR L-band satellite-borne instrument reveal local areas that are subsiding at rates that reach a few cm per month. Subsiding areas identified on radar interferograms enable labor-intensive ground investigations (such as microgravity surveys) to focus on areas where subsidence is occurring and shallow-source mass deficits might exist that could be sites of future subsidence or collapse. Longer-term elevation changes are being quantified by comparing digital elevation models (DEMs) constructed from high-resolution airborne lidar data acquired over a 32-km2 area in 2013 with older, lower-resolution DEMs constructed from data acquired during the NASA- and NGA-sponsored Shuttle Radar Topographic Mission in February 2000 and from USGS aerial photogrammetry-derived topographic data from the 1960s. Total subsidence reaches more than 10 m over 45 years in some areas. Maximum rates of subsidence measured on annual (from InSAR) and decadal (from lidar) time scales are about 0.25 m/yr. In addition to showing the extent and magnitude of subsidence at the 1980 and 2002 sinkholes, comparison of the 2013 lidar-derived DEM with the 1960s photogrammetry-derived DEM revealed other locations that have undergone significant (more than 1 m) elevation change since the 1960s, but show no evidence of recent (2008 to 2011) ground motion from satellite radar interferograms. Regional coverage obtained by radar interferometry and local coverage obtained with airborne lidar show that areas of measurable subsidence are all within a few km of the 1980 and 2002 sinkholes.

Persistent Scatterer Interferometry subsidence data exploitation using spatial tools: The Vega Media of the Segura River Basin case study

NASA Astrophysics Data System (ADS)

Tomas, R.; Herrera, G.; Cooksley, G.; Mulas, J.

2011-04-01

SummaryThe aim of this paper is to analyze the subsidence affecting the Vega Media of the Segura River Basin, using a Persistent Scatterers Interferometry technique (PSI) named Stable Point Network (SPN). This technique is capable of estimating mean deformation velocity maps of the ground surface and displacement time series from Synthetic Aperture Radar (SAR) images. A dataset acquired between January 2004 and December 2008 from ERS-2 and ENVISAT sensors has been processed measuring maximum subsidence and uplift rates of -25.6 and 7.54 mm/year respectively for the whole area. These data have been validated against ground subsidence measurements and compared with subsidence triggering and conditioning factors by means of a Geographical Information System (GIS). The spatial analysis shows a good relationship between subsidence and piezometric level evolution, pumping wells location, river distance, geology, the Arab wall, previously proposed subsidence predictive model and soil thickness. As a consequence, the paper shows the usefulness and the potential of combining Differential SAR Interferometry (DInSAR) and spatial analysis techniques in order to improve the knowledge of this kind of phenomenon.

Early radiological and functional outcomes for a cementless press-fit design modular femoral stem revision system.

PubMed

Hancock, Douglas S; Sharplin, Paul K; Larsen, Peter D; Phillips, Fredrick Ts

2018-05-01

To assess early radiological and functional outcomes of revision hip surgery with a cementless press-fit design femoral stem. A retrospective review of 48 consecutive revision total hip replacements using the RECLAIM revision hip system, between October 2012 and August 2015. Radiographic assessment was undertaken with serial anteroposterior (AP) X-rays of the pelvis. Risk factors for subsidence were evaluated. Prospective clinical follow up was performed on 21 patients to assess functional outcomes. Mean stem subsidence was 1.1 mm (95% confidence interval[CI]: 0.63-1.57). Median follow up of 12 months. An inverse relationship was observed between level of subsidence and femoral stem diameter r = -0.45, p = 0.001. Subsidence at the time of follow-up assessment was correlated with initial subsidence (correlation coefficient rho 0.69, p = 0.001). The mean Merle d'Aubigne score at the latest follow up was 14.2 (range 8-17). The mean OHS was 34.1 (range 15-48). Early radiological and functional outcomes for the RECLAIM revision system showed very low levels of subsidence and good functional outcomes. There was an association with smaller diameter femoral stems and greater levels of subsidence.

A Simple Model to Describe the Relationship among Rainfall, Groundwater and Land Subsidence under a Heterogeneous Aquifer

NASA Astrophysics Data System (ADS)

Zheng, Y. Y.; Chen, Y. L.; Lin, H. R.; Huang, S. Y.; Yeh, T. C. J.; Wen, J. C.

2017-12-01

Land subsidence is a very serious problem of Zhuoshui River alluvial fan, Taiwan. The main reason of land subsidence is a compression of soil, but the compression measured in the wide area is very extensive (Maryam et al., 2013; Linlin et al., 2014). Chen et al. [2010] studied the linear relationship between groundwater level and subsurface altitude variations from Global Positioning System (GPS) station in Zhuoshui River alluvial fan. But the subsurface altitude data were only from two GPS stations. Their distributions are spared and small, not enough to express the altitude variations of Zhuoshui River alluvial fan. Hung et al. [2011] used Interferometry Synthetic Aperture Radar (InSAR) to measure the surface subsidence in Zhuoshui River alluvial fan, but haven't compared with groundwater level. The study compares the correlation between rainfall events and groundwater level and compares the correlation between groundwater level and subsurface altitude, these two correlation affected by heterogeneous soil. From these relationships, a numerical model is built to simulate the land subsidence variations and estimate the coefficient of aquifer soil compressibility. Finally, the model can estimate the long-term land subsidence. Keywords: Land Subsidence, InSAR, Groundwater Level, Numerical Model, Correlation Analyses

Population condition analysis of Jakarta land deformation area

NASA Astrophysics Data System (ADS)

Putri, R. F.; Wibirama, S.; Sukamdi; Giyarsih, S. R.

2018-04-01

Jakarta is located in the North West area of West Java Province which geographically positioned on 106°33’00”-107°00’00”BT and 5°48’30”-6°24’00”LS. Land subsidence has occured in several types of landuse such as trade, industrial and settlement area of the urban area of Jakarta. The land subsidence disaster is one of the consequences of building and road construction in Jakarta. This is caused by massive groundwater utilization and failure in landuse planning. This study aim to analyze the population density and settlement pattern in the urban area of Jakarta which the occurence of land subsidence has been detected. It is important to understand landuse and settlement planning processes in the area which land subsidence occured. Detection of land subsidence distribution become a necessary parameter in landuse planning. While the land subsidence area detected using Differential Synthetic Aperture Radar (DInSAR) method. The result shows the area which land subsidence occured has a very high population density and clustered and linear settlement pattern. This area is mainly used as industrial, trade, and settlement.

Environmental impact of geopressure - geothermal cogeneration facility on wetland resources and socioeconomic characteristics in Louisiana Gulf Coast region. Final report, October 10, 1983-September 31, 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smalley, A.M.; Saleh, F.M.S.; Fontenot, M.

1984-08-01

Baseline data relevant to air quality are presented. The following are also included: geology and resource assessment, design well prospects in southwestern Louisiana, water quality monitoring, chemical analysis subsidence, microseismicity, geopressure-geothermal subsidence modeling, models of compaction and subsidence, sampling handling and preparation, brine chemistry, wetland resources, socioeconomic characteristics, impacts on wetlands, salinity, toxic metals, non-metal toxicants, temperature, subsidence, and socioeconomic impacts. (MHR)

Numerical modeling of subsidence induced by hydrocarbon production in a reservoir in coastal Louisiana

NASA Astrophysics Data System (ADS)

Zhou, Y.; Voyiadjis, G.

2017-12-01

Subsidence has caused significant wetland losses in coastal Louisiana due to various anthropogenic and geologic processes. Releveling data from National Geodetic Survey show that one of the governing factors in the coastal Louisiana is hydrocarbon production, which has led to the acceleration of spatial- and temporal-dependent subsidence. This work investigates the influence of hydrocarbon production on subsidence for a typical reservoir, the Valentine field in coastal Louisiana, based on finite element modeling in the framework of poroelasticity and poroplasticity. Geertsma's analytical model is first used in this work to interpret the observed subsidence, for a disc-shaped reservoir embedded in a semi-infinite homogeneous elastic medium. Based on the calibrated elastic material properties, the authors set up a 3D finite element model and validate the numerical results with Geertsma's analytical model. As the plastic deformation of a reservoir in an inhomogeneous medium plays an important role in the compaction of the reservoir and the land subsidence, the authors further adopt a modified Cam-Clay model to take account of the plastic compaction of the reservoir. The material properties in the Cam-Clay model are calibrated based on the subsidence observed in the field and that in the homogeneous elastic case. The observed trend and magnitude of subsidence in the Valentine field can be approximately reproduced through finite element modeling in both the homogeneous elastic case and the inhomogeneous plastic case, by using the calibrated material properties. The maximum compaction in the inhomogeneous plastic case is around half of that in the homogeneous elastic case, and thus the ratio of subsidence over compaction is larger in the inhomogeneous plastic case for a softer reservoir embedded in a stiffer medium.

Differential subsidence in Mexico City and implications to its Collective Transport System (Metro).

NASA Astrophysics Data System (ADS)

Solano Rojas, D. E.; Wdowinski, S.; Cabral-Cano, E.; Osmanoglu, B.

2017-12-01

Mexico City is one of the fastest subsiding metropolis in the world. At displacement rates ranging from 0 to -380 [mm/yr], the complex geological setting is subjected to differential subsidence, which has led to damage, operation interruptions, and accidents to the Collective Transport System, or Metro. The Metro plays a critical role in Mexico City, carrying more than four million passengers per day. However, no previous study has focused on the deformation monitoring along the 93 km of the Metro surface railways, mainly because of the limitations of the traditional geodetic techniques. In this study, we use high-resolution Interferometric Synthetic Aperture Radar (InSAR) observations to monitor land subsidence throughout the city and quantify differential subsidence along surface Metro lines. Our analysis is based on 34 TerraSAR-X StripMap scenes acquired from May 2011 to June 2013 and 36 COSMO-SkyMed Stripmap scenes acquired from June 2011 to June 2012. The data were processed using the StaMPS InSAR time series technique, obtaining point densities of up to 4827 points/km2. Our post-processing methodologies include the following two components: (1) Detection of differential subsidence along the metro lines by calculating subsidence gradients, and (2) Detection of apparent uplift—areas subsiding slower than their surroundings—by using spatial frequency filtering. The two analyses allow us to recognize four main consequences of differential subsidence in the Metro system: 1. Deflection in elevated railways, 2. Deflection in street-level railways, 3. Columns with decreased loading capacity, and 4. Apparent uplift affecting surrounding infrastructure. Our results aim at shortening the large gap between scientific geodetic studies and applicable engineering parameters that can be used by local authorities in the city for maintenance and new lines development.

Model test on partial expansion in stratified subsidence during foundation pit dewatering

NASA Astrophysics Data System (ADS)

Wang, Jianxiu; Deng, Yansheng; Ma, Ruiqiang; Liu, Xiaotian; Guo, Qingfeng; Liu, Shaoli; Shao, Yule; Wu, Linbo; Zhou, Jie; Yang, Tianliang; Wang, Hanmei; Huang, Xinlei

2018-02-01

Partial expansion was observed in stratified subsidence during foundation pit dewatering. However, the phenomenon was suspected to be an error because the compression of layers is known to occur when subsidence occurs. A slice of the subsidence cone induced by drawdown was selected as the prototype. Model tests were performed to investigate the phenomenon. The underlying confined aquifer was generated as a movable rigid plate with a hinge at one end. The overlying layers were simulated with remolded materials collected from a construction site. Model tests performed under the conceptual model indicated that partial expansion occurred in stratified settlements under coordination deformation and consolidation conditions. During foundation pit dewatering, rapid drawdown resulted in rapid subsidence in the dewatered confined aquifer. The rapidly subsiding confined aquifer top was the bottom deformation boundary of the overlying layers. Non-coordination deformation was observed at the top and bottom of the subsiding overlying layers. The subsidence of overlying layers was larger at the bottom than at the top. The layers expanded and became thicker. The phenomenon was verified using numerical simulation method based on finite difference method. Compared with numerical simulation results, the boundary effect of the physical tests was obvious in the observation point close to the movable endpoint. The tensile stress of the overlying soil layers induced by the underlying settlement of dewatered confined aquifer contributed to the expansion phenomenon. The partial expansion of overlying soil layers was defined as inversed rebound. The inversed rebound was induced by inversed coordination deformation. Compression was induced by the consolidation in the overlying soil layers because of drainage. Partial expansion occurred when the expansion exceeded the compression. Considering the inversed rebound, traditional layer-wise summation method for calculating subsidence should be revised and improved.

Numerical simulation of the paleohydrology of glacial Lake Oshkosh, eastern Wisconsin, USA

USGS Publications Warehouse

Clark, J.A.; Befus, K.M.; Hooyer, T.S.; Stewart, P.W.; Shipman, T.D.; Gregory, C.T.; Zylstra, D.J.

2008-01-01

Proglacial lakes, formed during retreat of the Laurentide ice sheet, evolved quickly as outlets became ice-free and the earth deformed through glacial isostatic adjustment. With high-resolution digital elevation models (DEMs) and GIS methods, it is possible to reconstruct the evolution of surface hydrology. When a DEM deforms through time as predicted by our model of viscoelastic earth relaxation, the entire surface hydrologic system with its lakes, outlets, shorelines and rivers also evolves without requiring assumptions of outlet position. The method is applied to proglacial Lake Oshkosh in Wisconsin (13,600 to 12,900??cal yr BP). Comparison of predicted to observed shoreline tilt indicates the ice sheet was about 400??m thick over the Great Lakes region. During ice sheet recession, each of the five outlets are predicted to uplift more than 100??m and then subside approximately 30??m. At its maximum extent, Lake Oshkosh covered 6600??km2 with a volume of 111??km3. Using the Hydrologic Engineering Center-River Analysis System model, flow velocities during glacial outburst floods up to 9??m/s and peak discharge of 140,000??m3/s are predicted, which could drain 33.5??km3 of lake water in 10??days and transport boulders up to 3??m in diameter. ?? 2007 University of Washington.

Study of Ground Subsidence in North West Houston using GPS, LiDAR and InSAR techniques

NASA Astrophysics Data System (ADS)

Karacay, A.; Khan, S. D.

2012-12-01

Land subsidence can be caused by natural or human activities, such as carbonate dissolution, extraction of material from mines, soil compaction and fluid withdrawal. This phenomenon affects many cities around the world, such as Nagoya-Japan, Venice-Italy, San Joaquin Valley and Long Beach in California. Recent work by Engelkemeir et al, (2010), suggested that subsidence occurred as high as 5.6 cm/year in northwest Houston. The processes that may contribute to land subsidence in the Houston-Galveston area includes faulting, soil compaction, salt tectonic, water pumping and hydrocarbon extraction. This study aims to assess the possible role of water pumping on subsidence. Northwest Houston has two aquifer systems, the Evangeline and Chicot aquifers that dip in the southeast direction. The effect of water pumping on subsidence from these two aquifers was monitored using InSAR, GPS and LiDAR data. The data from eleven GPS stations were processed using Online Positioning User Service (OPUS) of National Geodetic Survey (NGS). Three of these GPS stations are Continuously Operating Reference Stations (CORS) and eight are Port-A-Measure (PAM) sites. All the GPS data were obtained from Harris-Galveston Subsidence District (HGSD). CORS sites were used as reference stations for processing GPS data from the PAM stations. GPS data show that subsidence rate in northwest Houston decreased to approximately 2 cm/year. In addition, the surface deformation is also estimated using Light Detection and Ranging (LiDAR) technique. For this purpose, raw LiDAR (LAS-Long ASCII Standart) files of 2001 and 2008 were processed. The subsidence rate near the Hockley Fault was calculated by applying zonal statistics method on LiDAR data which shows about 10 cm of subsidence in nine years. This result is supported by processed GPS data from PAM site 48 that show subsidence rate of 1.3 cm/yr. For the InSAR (Interferometric Synthetic Aperture Radar) technique, an image pair of PALSAR (The Phased Array type L-band Synthetic Aperture Radar) for 2008 was processed using Sarscape ENVI. The result demonstrates both uplift (approximately 5 mm near the Tomball salt dome) and subsidence (approximately 5.3 mm on the west part of Tomball region). In order to improve results, other image pairs from PALSAR, ERS1/2 and ENVISAT are being processed to monitor surface changes before and after 2000. Changes of groundwater level in the study area were observed, in order to distinguish the amount of land subsidence caused by groundwater withdrawal. The groundwater historical observation data were taken from The USGS National Water Information System (NWIS). The results of the groundwater level between 1990 and 2011 show approximately 0.5 m per year of water decline in the study area. Results of these complementary techniques will help in assessing the possible role of the water pumping from the subsurface on the subsidence in the area.

Demonstration of subsidence monitoring system

NASA Astrophysics Data System (ADS)

Conroy, P. J.; Gyarmaty, J. H.; Pearson, M. L.

1981-06-01

Data on coal mine subsidence were studied as a basis for the development of subsidence control technology. Installation, monitoring, and evaluation of three subsidence monitoring instrument systems were examined: structure performance, performance of supported systems, and performance of caving systems. Objectives of the instrument program were: (1) to select, test, assemble, install, monitor, and maintain all instrumentation required for implementing the three subsidence monitoring systems; and (2) to evaluate performance of each instrument individually and as part of the appropriate monitoring system or systems. The use of an automatic level and a rod extensometer for measuring structure performance, and the automatic level, steel tape extensometer, FPBX, FPBI, USBM borehole deformation gauge, and vibrating wire stressmeters for measuring the performance of caving systems are recommended.

Guidelines for sinkhole and subsidence rehabilitation based on generic geological models of a dolomite environment on the East Rand, South Africa

NASA Astrophysics Data System (ADS)

Kleinhans, Ilse; Van Rooy, J. Louis

2016-05-01

A sound understanding of the various factors influencing and associated with the formation of sinkholes or subsidences on dolomite land is essential for the selection of appropriate rehabilitation methods. The investigation and rehabilitation of numerous sinkholes and subsidences located on dolomite in the East Rand of South Africa, created an opportunity to develop a broad based understanding of different karst environments, their susceptibility to sinkhole and subsidence formation and best practice rehabilitation methods. This paper is based on the guidelines developed whereby the geological model of the sinkhole or subsidence is used to recommend an appropriate rehabilitation method. Nine typical geological models with recommended rehabilitation methods are presented in this paper.

Global positioning system surveying to monitor land subsidence in Sacramento Valley, California, USA

USGS Publications Warehouse

Ikehara, M.E.

1994-01-01

A subsidence research program began in 1985 to document the extent and magnitude of land subsidence in Sacramento Valley, California, an area of about 15 600 km2m, using Global Positioning System (GPS) surveying. In addition to periodic conventional spirit levelling, an examination was made of the changes in GPS-derived ellipsoidal height differences (summary differences) between pairs of adjacent bench marks in central Sacramento Valley from 1986 to 1989. The average rates of land subsidence in the southern Sacramento Valley for the past several decades were determined by comparing GPS-derived orthometric heights with historic published elevations. A maximum average rate of 0.053 m year-1 (0.90 m in 17 years) of subsidence has been measured. -Author

Investigation of subsidence in the Manfredonia Gulf (Southern Italy) through multitemporal DInSAR techniques

NASA Astrophysics Data System (ADS)

Triggiani, M.; Refice, A.; Capolongo, D.; Bovenga, F.; Caldara, M.

2009-04-01

We present results of an experiment aimed at detecting possible displacements due to subsidence in the coastal area of the Tavoliere plain, Puglia Region, in Southern Italy, through analysis of remotely sensed data. The Tavoliere is the second largest Italian plain. Its coastal area, between the urban centers of Manfredonia and Barletta, is composed of a 50 km long sandy beach (Manfredonia gulf), linking the Gargano massif at north with the Murge plateau in the south-east. Both areas belong to the carbonate Mesozoic Apulian platform. The current configuration of the Gulf was reached recently, as a consequence of the Holocene sea level rise. During the Neolithic age the plain was occupied by an elongated lagoon (Salpi Lagoon) [1]. During the 2nd century B.C., alluvial deposition caused the lagoon to be separated into two basins: the so-called Salpi lake at south and the Salso lake at north. To cope with the increasing demand of arable lands and with the necessity to make unhealthy areas accessible to humans, some reclaims were accomplished by diverting and channelling the rivers crossing the Tavoliere plain, and by levelling dune belts. At present, the beach is separated by low artificial dunes from the areas already reclaimed and intensely cultivated or exploited as evaporation basin for salt production. In the last decades, the coastal area has been retreating due to a reduction in sediment input necessary for coastal equilibrium. The levelling of dunes and the decrease of fluvial turbid discharge due to dam constructions are probably the cause of this deficit in sediment supply. During highly intense hydrodynamic and meteorological events, sea waters often penetrate deeply inland, flooding intensively cultivated areas. These events are occurring with growing frequency and rates. They are an indication of the possibility that those areas are subject to subsidence at a faster rate in comparison to the surroundings. An example is the salt marsh located inland of the tourist sea village "Ippocampo". Here, unpublished studies based on ground data indicate average subsidence rates of the order of 0.20 mm/y in the last 125 ka for the inland area next to the village. More recently, height maps issued by the Italian Military Geographic Institute (IGM) in the 1950s report heights a.s.l. of the order of a few m. Observing that today the area is practically at sea level, an average subsidence of the order of tens of mm/y can be inferred for the last 50 years. To gain insight into the recent evolution of these phenomena, we investigate vertical movements on the coastal Tavoliere area through multitemporal differential Interferometric synthetic aperture radar (DInSAR) techniques. We use a persistent scatterers interferometry (PSI) processing methodology [2] to estimate subsidence displacement rates from long temporal series of SAR acquisitions. PSI techniques, first developed at POLIMI [3], allow to retrieve phase information from stacks of co-registered SAR interferograms spanning many years and taken from different directions with large baselines, by restricting the analysis to selected image pixels containing single objects with strong radar backscatter returns. Exploiting the high temporal stability of radar returns from these targets, it is possible to correct the images from spurious phase contributions such as atmospheric phase artefacts and errors in the digital elevation models used to account for topographic InSAR phase. Such stable objects typically coincide with man-made features, so successful applications of PSI techniques are mainly reported over urban centers. We processed a total of 105 SAR images acquired from the ERS-1/2 and ENVISAT satellites, organized in 3 stacks related to both descending (50 ERS-1/2 scenes) and ascending (25 ERS-1/2 and 30 ENVISAT scenes) acquisition geometries. The acquisitions refer to the temporal periods from 1995 to 2000 (ERS) and 2003 to 2008 (ENVISAT), respectively, with a temporal repetition frequency of roughly 1 acquisition every 35 days. The 3 stacks, covering approximately the same ground area centred on the Tavoliere coastal plain, were processed independently. Reliable phase measurements were obtained over small urban centers and anthropogenic features scattered along the coast. Results from all 3 stacks indicate the presence of displacements occurring through the entire temporal interval of observation. In particular, displacements appear spatially organized as a subsidence "bowl" centered approximately around the area of Zapponeta, with maximum subsidence rates exceeding 20 mm/y. The detected displacements appear consistent with the average rates deduced heuristically from analysis of the environmental settings as exposed above. Moreover, they also qualitatively agree with other investigations performed using analogous techniques and data over the region (e.g. [4]). Possible interpretation of these results can be attempted by considering that the area has been repeatedly subject to reclaiming through filling, and that the deposited sediments are most exposed to compaction. Moreover, the area is subject to intense water extraction, which further enhances the effects of sediment compaction. Validation of the obtained measurements is in progress through extended data analysis and in situ activities. However, these preliminary analyses and comparisons between InSAR and ground data hint to the possible presence of two co-existing subsidence phenomena in the area: a natural subsidence due to tectonics or isostatic rebound, with slow subsidence effects occurring over geologic time scales, with an additional, more pronounced subsidence phenomenon on the recent sediment deposits due to sediment compaction under lithostatic loading, and an anthropogenic local, accelerated subsidence on the lowest areas, due to intensive draining mostly for irrigation purposes, which adds to recent land remediation actions to cause a worrisome lowering of the water table in the area. References [1] F. Boenzi, M. Caldara, M. Moresi, L. Pennetta 2002, "History of the Salpi lagoon-sabhka (Manfredonia Gulf, Italy)". Il Quaternario, 14, 93-104. 2001 [2] F. Bovenga, A. Refice, R. Nutricato, L. Guerriero, M.T. Chiaradia, "SPINUA: a flexible processing chain for ERS / ENVISAT long term interferometry", Proceedings of ESA-ENVISAT Symposium, Salzburg, Austria, 6-10 September, 2004. [3] Ferretti, A., Prati, C., Rocca, F. "Permanent Scatterers in SAR Interferometry". IEEE Transactions on Geoscience and Remote Sensing 39, 8-20, 2001. [4] S. Salvi, S. Atzori, C.A. Brunori, F. Doumaz, G.P. Ricciardi, G. Solaro, S. Stramondo, C. Tolomei, R. Lanari, A. Pepe, A. Ferretti, S. Cespa, "The VELISAR initiative for the measurement of ground velocity in italian seismogenic areas", EGU General Assembly, Wien, Austria, 15-20 April, 2007.

The structure and stratigraphy of deepwater Sarawak, Malaysia: Implications for tectonic evolution

NASA Astrophysics Data System (ADS)

Madon, Mazlan; Kim, Cheng Ly; Wong, Robert

2013-10-01

The structural-stratigraphic history of the North Luconia Province, Sarawak deepwater area, is related to the tectonic history of the South China Sea. The Sarawak Basin initiated as a foreland basin as a result of the collision of the Luconia continental block with Sarawak (Sarawak Orogeny). The foreland basin was later overridden by and buried under the prograding Oligocene-Recent shelf-slope system. The basin had evolved through a deep foreland basin ('flysch') phase during late Eocene-Oligocene times, followed by post-Oligocene ('molasse') phase of shallow marine shelf progradation to present day. Seismic interpretation reveals a regional Early Miocene Unconformity (EMU) separating pre-Oligocene to Miocene rifted basement from overlying undeformed Upper Miocene-Pliocene bathyal sediments. Seismic, well data and subsidence analysis indicate that the EMU was caused by relative uplift and predominantly submarine erosion between ˜19 and 17 Ma ago. The subsidence history suggests a rift-like subsidence pattern, probably with a foreland basin overprint during the last 10 Ma. Modelling results indicate that the EMU represents a major hiatus in the sedimentation history, with an estimated 500-2600 m of missing section, equivalent to a time gap of 8-10 Ma. The EMU is known to extend over the entire NW Borneo margin and is probably related to the Sabah Orogeny which marks the cessation of sea-floor spreading in the South China Sea and collision of Dangerous Grounds block with Sabah. Gravity modelling indicates a thinned continental crust underneath the Sarawak shelf and slope and supports the seismic and well data interpretation. There is a probable presence of an overthrust wedge beneath the Sarawak shelf, which could be interpreted as a sliver of the Rajang Group accretionary prism. Alternatively, magmatic underplating beneath the Sarawak shelf could equally explain the free-air gravity anomaly. The Sarawak basin was part of a remnant ocean basin that was closed by oblique collision along the NW Borneo margin. The closure started in the Late Eocene in Sarawak and moved progressively northeastwards into Sabah until the Middle Miocene. The present-day NW Sabah margin may be a useful analogue for the Oligocene-Miocene Sarawak foreland basin.

Sea Level Change due to Time-Dependent Long-Wavelength Dynamic Topography Inferred from Plate Tectonic Reconstructions

NASA Astrophysics Data System (ADS)

Conrad, Clinton P.; Steinberger, Bernhard; Torsvik, Trond H.

2017-04-01

Earth's surface is deflected vertically by stresses associated with convective mantle flow. Although dynamic topography is important for both sea level change and continental uplift and subsidence, the time history of dynamic topography is difficult to constrain because the time-dependence of mantle flow is not known. However, the motions of the tectonic plates contain information about the mantle flow patterns that drive them. In particular, we show that the longest wavelengths of mantle flow are tightly linked to the dipole and quadrupole moments (harmonic degrees 1 and 2) of plate motions. This coupling allows us to infer patterns of long-wavelength mantle flow, and the associated dynamic topography, from tectonic plate motions. After calibrating this linkage using models of present-day mantle flow, we can use reconstructions of global plate motions to infer the basic patterns of long-wavelength dynamic topography back to 250 Ma. We find relatively stable dynamic uplift persists above large-scale mantle upwelling beneath Africa and the Central Pacific. Regions of major downwelling encircled the periphery of these stable upwellings, alternating between primarily east-west and north-south orientations. The amplitude of long-wavelength dynamic topography was likely largest in the Cretaceous, when global plate motions were fastest. Continental motions over this time-evolving dynamic topography predict patterns of continental uplift and subsidence that are confirmed by geological observations of continental surfaces relative to sea level. Net uplift or subsidence of the global seafloor can also induce eustatic sea level changes. We infer that dispersal of the Pangean supercontinent away from stable upwelling beneath Africa may have exposed the seafloor to an increasingly larger area of growing positive dynamic topography during the Mesozoic. This net uplift of the seafloor caused 60 m of sea level rise during the Triassic and Jurassic, ceasing in the Cenozoic once continents fully override degree-2 downwellings. These sea level changes represent a significant component of the estimated 200 m of sea level variations during the Phanerozoic, which exhibit a similar temporal pattern.

Impacts of 25 years of groundwater extraction on subsidence in the Mekong delta, Vietnam

EPA Science Inventory

Many major river deltas in the world are subsiding and consequently become increasingly vulnerable to flooding and storm surges, salinization and permanent inundation. For the Mekong Delta, annual subsidence rates up to several centimetres have been reported. Excessive groundwate...

78 FR 16362 - Proposed Collection; Comment Request for Form 6497

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-14

... 6497, Information Return of Nontaxable Energy Grants or Subsidized Energy Financing. DATES: Written... Grants or Subsidized Energy Financing. OMB Number: 1545-0232. Form Number: Form 6497. Abstract: Section... Federal, state, or local program providing nontaxable grants or subsidized energy financing. Form 6497 is...

Landslide and Land Subsidence Hazards to Pipelines

USGS Publications Warehouse

Baum, Rex L.; Galloway, Devin L.; Harp, Edwin L.

2008-01-01

Landslides and land subsidence pose serious hazards to pipelines throughout the world. Many existing pipeline corridors and more and more new pipelines cross terrain that is affected by either landslides, land subsidence, or both. Consequently the pipeline industry recognizes a need for increased awareness of methods for identifying and evaluating landslide and subsidence hazard for pipeline corridors. This report was prepared in cooperation with the U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration, and Pipeline Research Council International through a cooperative research and development agreement (CRADA) with DGH Consulting, Inc., to address the need for up-to-date information about current methods to identify and assess these hazards. Chapters in this report (1) describe methods for evaluating landslide hazard on a regional basis, (2) describe the various types of land subsidence hazard in the United States and available methods for identifying and quantifying subsidence, and (3) summarize current methods for investigating individual landslides. In addition to the descriptions, this report provides information about the relative costs, limitations and reliability of various methods.

Amendment to "Analytical Solution for the Convectively-Mixed Atmospheric Boundary Layer": Inclusion of Subsidence

NASA Astrophysics Data System (ADS)

Ouwersloot, H. G.; de Arellano, J. Vilà-Guerau

2013-09-01

In Ouwersloot and Vilà-Guerau de Arellano (Boundary-Layer Meteorol. doi: 10.1007/s10546-013-9816-z , 2013, this issue), the analytical solutions for the boundary-layer height and scalar evolutions are derived for the convective boundary layer, based on the prognostic equations of mixed-layer slab models without taking subsidence into account. Here, we include and quantify the added effect of subsidence if the subsidence velocity scales linearly with height throughout the atmosphere. This enables analytical analyses for a wider range of observational cases. As a demonstration, the sensitivity of the boundary-layer height and the potential temperature jump to subsidence and the free tropospheric stability is graphically presented. The new relations show the importance of the temporal distribution of the surface buoyancy flux in determining the evolution if there is subsidence.

Health Diagnosis of Major Transportation Infrastructures in Shanghai Metropolis Using High-Resolution Persistent Scatterer Interferometry

PubMed Central

Qin, Xiaoqiong; Yang, Tianliang; Yang, Mengshi; Zhang, Lu; Liao, Mingsheng

2017-01-01

Since the Persistent Scatterer Synthetic Aperture Radar (SAR) Interferometry (PSI) technology allows the detection of ground subsidence with millimeter accuracy, it is becoming one of the most powerful and economical means for health diagnosis of major transportation infrastructures. However, structures of different types may suffer from various levels of localized subsidence due to the different structural characteristics and subsidence mechanisms. Moreover, in the complex urban scenery, some segments of these infrastructures may be sheltered by surrounding buildings in SAR images, obscuring the desirable signals. Therefore, the subsidence characteristics on different types of structures should be discussed separately and the accuracy of persistent scatterers (PSs) should be optimized. In this study, the PSI-based subsidence mapping over the entire transportation network of Shanghai (more than 10,000 km) is illustrated, achieving the city-wide monitoring specifically along the elevated roads, ground highways and underground subways. The precise geolocation and structural characteristics of infrastructures were combined to effectively guide more accurate identification and separation of PSs along the structures. The experimental results from two neighboring TerraSAR-X stacks from 2013 to 2016 were integrated by joint estimating the measurements in the overlapping area, performing large-scale subsidence mapping and were validated by leveling data, showing highly consistent in terms of subsidence velocities and time-series displacements. Spatial-temporal subsidence patterns on each type of infrastructures are strongly dependent on the operational durations and structural characteristics, as well as the variation of the foundation soil layers. PMID:29186039

Application of decision tree model for the ground subsidence hazard mapping near abandoned underground coal mines.

PubMed

Lee, Saro; Park, Inhye

2013-09-30

Subsidence of ground caused by underground mines poses hazards to human life and property. This study analyzed the hazard to ground subsidence using factors that can affect ground subsidence and a decision tree approach in a geographic information system (GIS). The study area was Taebaek, Gangwon-do, Korea, where many abandoned underground coal mines exist. Spatial data, topography, geology, and various ground-engineering data for the subsidence area were collected and compiled in a database for mapping ground-subsidence hazard (GSH). The subsidence area was randomly split 50/50 for training and validation of the models. A data-mining classification technique was applied to the GSH mapping, and decision trees were constructed using the chi-squared automatic interaction detector (CHAID) and the quick, unbiased, and efficient statistical tree (QUEST) algorithms. The frequency ratio model was also applied to the GSH mapping for comparing with probabilistic model. The resulting GSH maps were validated using area-under-the-curve (AUC) analysis with the subsidence area data that had not been used for training the model. The highest accuracy was achieved by the decision tree model using CHAID algorithm (94.01%) comparing with QUEST algorithms (90.37%) and frequency ratio model (86.70%). These accuracies are higher than previously reported results for decision tree. Decision tree methods can therefore be used efficiently for GSH analysis and might be widely used for prediction of various spatial events. Copyright © 2013. Published by Elsevier Ltd.

Groundwater-flow and land-subsidence model of Antelope Valley, California

USGS Publications Warehouse

Siade, Adam J.; Nishikawa, Tracy; Rewis, Diane L.; Martin, Peter; Phillips, Steven P.

2014-01-01

Results from the first scenario indicated that the total drawdown observed since predevelopment would continue, with values exceeding 325 ft near Palmdale; consequently, land subsidence would also continue, with additional subsidence (since 2005) exceeding 3 ft in the central part of the Lancaster subbasin. The second scenario evaluated redistributing pumpage from areas in the Lancaster subbasin where simulated hydraulic-head declines were the greatest to areas where declines were smallest. Neither a formal optimization algorithm nor water-rights allocations were considered when redistributing the pumpage. Results indicated that hydraulic heads near Palmdale, where the pumpage was reduced, would recover by about 200 ft compared to 2005 conditions, with only 30 ft of additional drawdown in the northwestern part of the Lancaster subbasin, where the pumpage was increased. The magnitude of the simulated additional land subsidence decreased slightly compared to the first, status quo, scenario but land subsidence continued to be simulated throughout most of the northern part of the Lancaster subbasin. The third scenario consisted of two artificial-recharge simulations along the Upper Amargosa Creek channel and at a site located north of Antelope Buttes. Results indicate that applying artificial recharge at these sites would yield continued drawdowns and associated land subsidence. However, the magnitudes of drawdown and subsidence would be smaller than those simulated in the status quo scenario, indicating that artificial-recharge operations in the Antelope Valley could be expected to reduce the magnitude and extent of continued water-level declines and associated land subsidence.

Health Diagnosis of Major Transportation Infrastructures in Shanghai Metropolis Using High-Resolution Persistent Scatterer Interferometry.

PubMed

Qin, Xiaoqiong; Yang, Tianliang; Yang, Mengshi; Zhang, Lu; Liao, Mingsheng

2017-11-29

Since the Persistent Scatterer Synthetic Aperture Radar (SAR) Interferometry (PSI) technology allows the detection of ground subsidence with millimeter accuracy, it is becoming one of the most powerful and economical means for health diagnosis of major transportation infrastructures. However, structures of different types may suffer from various levels of localized subsidence due to the different structural characteristics and subsidence mechanisms. Moreover, in the complex urban scenery, some segments of these infrastructures may be sheltered by surrounding buildings in SAR images, obscuring the desirable signals. Therefore, the subsidence characteristics on different types of structures should be discussed separately and the accuracy of persistent scatterers (PSs) should be optimized. In this study, the PSI-based subsidence mapping over the entire transportation network of Shanghai (more than 10,000 km) is illustrated, achieving the city-wide monitoring specifically along the elevated roads, ground highways and underground subways. The precise geolocation and structural characteristics of infrastructures were combined to effectively guide more accurate identification and separation of PSs along the structures. The experimental results from two neighboring TerraSAR-X stacks from 2013 to 2016 were integrated by joint estimating the measurements in the overlapping area, performing large-scale subsidence mapping and were validated by leveling data, showing highly consistent in terms of subsidence velocities and time-series displacements. Spatial-temporal subsidence patterns on each type of infrastructures are strongly dependent on the operational durations and structural characteristics, as well as the variation of the foundation soil layers.

Contrasting modes of rifting: The Benue Trough and Cameroon Volcanic Line, West Africa

NASA Astrophysics Data System (ADS)

Okereke, C. S.

1988-08-01

The Benue trough of west Africa is commonly believed to be a rift feature that originated in the Cretaceous at about the time that Africa and South America began to separate. Bouguer gravity and available geological data in the trough indicate that its formation was probably the result of regional horizontal stresses in the lithosphere, causing crustal extension and surface subsidence. By contrast, the data for the adjoining Cameroon volcanic line suggests that the associated tensional stresses relate to mantle upwarp causing thinning of the lithosphere and regional crustal uplift similar to that associated with the Kenya rift. Thus the association of passive and active rifts seen in the Afro-Arabia rift system is also a feature of the Cretaceous rift system in west Africa.

Assessing the long-term impact of subsidence and global climate change on emergency evacuation routes in coastal Louisiana.

DOT National Transportation Integrated Search

2012-12-01

Subsidence forecast models for coastal Louisiana were developed to estimate the change in surface elevations of evacuation routes for the years 2015, 2025, 2050, and 2100. Geophysical and anthropogenic subsidence estimates were derived from on-going ...

Historical and contingent factors affect re-evolution of a complex feature lost during mass extinction in communities of digital organisms.

PubMed

Yedid, G; Ofria, C A; Lenski, R E

2008-09-01

Re-evolution of complex biological features following the extinction of taxa bearing them remains one of evolution's most interesting phenomena, but is not amenable to study in fossil taxa. We used communities of digital organisms (computer programs that self-replicate, mutate and evolve), subjected to periods of low resource availability, to study the evolution, loss and re-evolution of a complex computational trait, the function EQU (bit-wise logical equals). We focused our analysis on cases where the pre-extinction EQU clade had surviving descendents at the end of the extinction episode. To see if these clades retained the capacity to re-evolve EQU, we seeded one set of multiple subreplicate 'replay' populations using the most abundant survivor of the pre-extinction EQU clade, and another set with the actual end-extinction ancestor of the organism in which EQU re-evolved following the extinction episode. Our results demonstrate that stochastic, historical, genomic and ecological factors can lead to constraints on further adaptation, and facilitate or hinder re-evolution of a complex feature.

High resolution spectroscopy of the disk chromosphere. II - Time sequence observations of Ca II H and K emissions.

NASA Technical Reports Server (NTRS)

Wilson, P. R.; Rees, D. E.; Beckers, J. M.; Brown, D. R.

1972-01-01

Two independent sets of high resolution time series spectra of the Ca II H and K emission obtained at the Solar Tower and at the Big Dome of the Sacramento Peak Observatory on September 11th, 1971 are reported. The evolutionary behavior of the emission first reported by Wilson and Evans is confirmed, but the detail of the evolution is found to be more complex. In one case, a doubly peaked feature showing some K3 emission evolves into a single K2 (red) peak with no K3 emission. Coincidentally, a neighboring doubly peaked feature evolves to a very strong blue peak. In an entirely independent sequence a doubly peaked feature evolves into a single red peak. The K2 emission then fades completely although the continuum threads are still strong. Finally a strong K2 blue peak appears. It is concluded that the observed evolution of the K2 emission is due to temporal variations in the physical conditions which give rise to them.

30 CFR 819.17 - Auger mining: Subsidence protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance with...

Does Federally Subsidized Rental Housing Depress Neighborhood Property Values?

ERIC Educational Resources Information Center

Ellen, Ingrid Gould; Schwartz, Amy Ellen; Voicu, Ioan; Schill, Michael H.

2007-01-01

Few communities welcome federally subsidized rental housing, with one of the most commonly voiced fears being reductions in property values. Yet there is little empirical evidence that subsidized housing depresses neighborhood property values. This paper estimates and compares the neighborhood impacts of a broad range of federally subsidized…

30 CFR 819.17 - Auger mining: Subsidence protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance with...

Growth and degradation of Hawaiian volcanoes: Chapter 3 in Characteristics of Hawaiian volcanoes

USGS Publications Warehouse

Clague, David A.; Sherrod, David R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

2014-01-01

Large Hawaiian volcanoes can persist as islands through the rapid subsidence by building upward rapidly enough. But in the long run, subsidence, coupled with surface erosion, erases any volcanic remnant above sea level in about 15 m.y. One consequence of subsidence, in concert with eustatic changes in sea level, is the drowning of coral reefs that drape the submarine flanks of the actively subsiding volcanoes. At least six reefs northwest of the Island of Hawai‘i form a stairstep configuration, the oldest being deepest.

Investigation of Potential Landsubsidence using GNSS CORS UDIP and DinSAR, Sayung, Demak, Indonesia

NASA Astrophysics Data System (ADS)

Yuwono, B. D.; Prasetyo, Y.; Islama, L. J. F.

2018-02-01

The coastal flooding induced by land subsidence is one of major social problems in the coastal area of Central Java, especially North Demak. Recent advance technology Global Navigation Satellite System Continuously Operating System (GNSS) and Differential Synthetic Aperture Radar Interferometry ( DInSAR) is already increased our capability to identify of land subsidence processes. DInSAR required not only availability of good quality input data but also rigorous approaches. In this research we used DInSAR analysis with focusing on landsubsidence phenomena. Tests were done with geodetic GPS survey with GNSS CORS UDIP as base station. Performance assessment of development method was conducted on study area affected by land subsidence. The results of this study indicate land subsidence spreads in study area with varying degrees of subsidence.

Integration of MODIS data and Short Baseline Subset (SBAS) technique for land subsidence monitoring in Datong, China

NASA Astrophysics Data System (ADS)

Zhao, Chao-ying; Zhang, Qin; Yang, Chengsheng; Zou, Weibao

2011-07-01

Datong is located in the north of Shanxi Province, which is famous for its old-fashioned coal-mining preservation in China. Some serious issues such as land subsidence, ground fissures, mining collapse, and earthquake hazards have occurred over this area for a long time resulting in significant damages to buildings and roads. In order to monitor and mitigate these natural man-made hazards, Short Baseline Subsets (SBAS) InSAR technique with ten Envisat ASAR data is applied to detect the surface deformation over an area of thousands of square kilometers. Then, five MODIS data are used to check the atmospheric effects on InSAR interferograms. Finally, nine nonlinear land subsidence cumulative results during September 2004 and February 2008 are obtained. Based on the deformation data, three kinds of land subsidence are clearly detected, caused by mine extraction, underground water withdrawal and construction of new economic zones, respectively. The annual mean velocity of subsidence can reach 1 to 4 cm/year in different subsidence areas. A newly designed high-speed railway (HSR) with speeds of 350 km/h will cross through the Datong hi-tech zone. Special measures should be taken for the long run of this project. In addition, another two subsidence regions need further investigation to mitigate such hazards.

Approximate land-surface subsidence in Fort Bend County, Texas, 1943-87 and 1973-87

USGS Publications Warehouse

Gabrysch, R.K.; Coplin, L.S.

1998-01-01

Land-surface subsidence resulting from the lowering of water levels that accompany ground-water development in areas of the Texas Gulf Coast has been described in numerous reports, newspapers, and magazines since the 1950s. Gabrysch and Bonnet (1975), Gabrysch (1984), and Gabrysch and Coplin (1990) presented subsidence maps of the Houston-Galveston region, including Fort Bend County, for a number of time periods. Most of the subsidence has been in the Houston area. This report, prepared in cooperation with the Fort Bend Subsidence District and the Harris-Galveston Coastal Subsidence District, presents contour maps of land-surface subsidence in Fort Bend County that occurred during 1943-87 and 1973-87.Fort Bend County is underlain by a thick section of unconsolidated lenticular deposits of sand and clay. The deposits include the principal aquifers in the county – the Evangeline aquifer and the overlying Chicot aquifer. Within these aquifers, the interbedded sands and clays are saturated with water almost to the land surface. The sand layers generally are connected laterally, but the clays retard the vertical movement of water, creating confined (artesian) conditions within the aquifer. The sands are fine to medium grained, and the combined layers yield large quantities of water. The clays are principally montmorillonite, the most compressible of the clay minerals.

Using temporarily coherent point interferometric synthetic aperture radar for land subsidence monitoring in a mining region of western China

NASA Astrophysics Data System (ADS)

Fan, Hongdong; Xu, Qiang; Hu, Zhongbo; Du, Sen

2017-04-01

Yuyang mine is located in the semiarid western region of China where, due to serious land subsidence caused by underground coal exploitation, the local ecological environment has become more fragile. An advanced interferometric synthetic aperture radar (InSAR) technique, temporarily coherent point InSAR, is applied to measure surface movements caused by different mining conditions. Fifteen high-resolution TerraSAR-X images acquired between October 2, 2012, and March 27, 2013, were processed to generate time-series data for ground deformation. The results show that the maximum accumulated values of subsidence and velocity were 86 mm and 162 mm/year, respectively; these measurements were taken above the fully mechanized longwall caving faces. Based on the dynamic land subsidence caused by the exploitation of one working face, the land subsidence range was deduced to have increased 38 m in the mining direction with 11 days' coal extraction. Although some mining faces were ceased in 2009, they could also have contributed to a small residual deformation of overlying strata. Surface subsidence of the backfill mining region was quite small, the maximum only 21 mm, so backfill exploitation is an effective method for reducing the land subsidence while coal is mined.

Six years of land subsidence in shanghai revealed by JERS-1 SAR data

USGS Publications Warehouse

Damoah-Afari, P.; Ding, X.-L.; Li, Z.; Lu, Z.; Omura, M.

2008-01-01

Differential interferometric synthetic aperture radar (SAR) (DInSAR) has proven to be very useful in mapping and monitoring land subsidence in many regions of the world. Shanghai, China's largest city, is one of such areas suffering from land subsidence as a result of severe withdrawal of groundwater for different usages. DInSAR application in Shanghai with the C-band European Remote Sensing 1 & 2 (ERS-1/2) SAR data has been difficult mainly due to the problem of decorrelation of InSAR pairs with temporal baselines larger than 10 months. To overcome the coherence loss of C-band InSAR data, we used eight L-band Japanese Earth Resource Satellite (JERS-1) SAR data acquired during 2 October 1992 to 15 July 1998 to study land subsidence phenomenon in Shanghai. Three of the images were used to produce two separate digital elevation models (DEMs) of the study area to remove topographic fringes from the interferograms used for subsidence mapping. Six interferograms were used to generate 2 different time series of deformation maps over Shanghai. The cumulative subsidence map generated from each of the time series is in agreement with the land subsidence measurements of Shanghai city from 1990-1998, produced from other survey methods. ?? 2007 IEEE.

Hazards of Gulf Coast Subsidence: Crustal Loading, Geodesy, InSAR and UAVSAR Observations

NASA Astrophysics Data System (ADS)

Blom, R. G.; Chapman, B. D.; Dokka, R. K.; Fielding, E. J.; Hensley, S.; Ivins, E. R.; Lohman, R. B.

2009-12-01

Hurricanes Katrina and Rita focused attention on the vulnerability of the U.S. Gulf Coast. Significant improvement in geophysical understanding of subsidence rates, temporal variability, and geographic distribution is not only an interesting scientific challenge, it is necessary for long term protection of lives and property. An integrated geophysical approach using precise and accurate geodetic measurements is the only way to gain physical insight into the myriad of possible processes at work and provide accurate predictions of future subsidence rates. In particular, southeast Louisiana is a Holocene landscape built on a coastal delta created by the Mississippi River during the past ~8,000 years as sea level rise slowed. Prior to human intervention natural subsidence was offset by sediment deposition by the Mississippi River during floods, and in situ organic sediment production in marshes. Currently, several processes have been documented to contribute to subsidence, including wetland loss due to lack of present day sediment flux, land subsidence due to sediment compaction, sediment oxidation, fluid withdrawal, salt evacuation, tectonics, and also crustal loading. One of the least studied subsidence driving phenomena is the effect of crustal loading due to Mississippi River sediments, and the geologically recent ~130 m (427 ft.) rise in sea level. We model subsidence rates expected from these loads using geophysical methods developed for post-glacial rebound. Our model predicted, and geodetically observed, vertical subsidence rates vary between 2 - 8 mm per year over areas of 30,000 to 750 square kilometers, respectively. This viscoelastic flexure is the background crustal deformation field, upon which larger amplitude, but smaller spatial scale, subsidence occurs due to other factors. We are extending subsidence measurements from traditional geodetic techniques (including GPS), to geographically comprehensive measurements derived from synthetic aperture radar interferometry (InSAR) using both satellite and airborne radars. The Gulf Coast is a very challenging environment for InSAR techniques and we are developing new persistent scatterer methods to apply to available C-band satellite radar data. More recent L-Band PALSAR satellite data are suitable for conventional interferometry. We are also making new observations with NASA/JPL’s new airborne interferometer system UAVSAR (http://uavsar.jpl.nasa.gov/). The high spatial resolution UAVSAR data has the potential to monitor levees and other critical infrastructure better than satellites. We review work to date and present newly acquired UAVSAR data.

On Assessment and Estimation of Potential Losses due to Land Subsidence in Urban Areas of Indonesia

NASA Astrophysics Data System (ADS)

Abidin, Hasanuddin Z.; Andreas, Heri; Gumilar, Irwan; Sidiq, Teguh P.

2016-04-01

Land subsidence is natural-anthropogenic hazard affecting several large urban areas in Indonesia, i.e. Jakarta, Bandung and Semarang. Geodetic based results from various techniques (e.g. Leveling, GPS and InSAR) show that land subsidence rates in all three cities generally have spatial and temporal variations, and their magnitude is in average about 5-10 cm/year. The impacts of subsidence in those cities can be seen in the field in various forms such as cracking of permanent constructions and roads, tilting of houses and buildings, 'sinking' of houses and buildings, changes in river canal and drain flow systems, wider expansion of coastal and/or inland flooding areas, and increased inland sea water intrusion. These impacts can be categorized into infrastructure, environmental, economic, and social impacts. The potential losses due to land subsidence in urban areas are actually quite significant. Related infrastructural, social and environmental costs due to direct and indirect impacts of land subsidence are economically quite significant, and can not be underestimated in sustainable urban development. The planning, development and maintenance costs of building and infrastructures in the affected areas are usually much higher than the normal situation. The collateral impact of coastal subsidence in Jakarta and Semarang, in the form of coastal flooding during high tides is also quite damaging. This repeated coastal flooding in several areas along the coast will deteriorate the structure and function of building and infrastructures, badly influences the quality of the living environment and life (e.g. health and sanitation condition), and also disrupts economic and social activities in the affected areas. As in the case of Bandung, inland subsidence also has a quite significant impact on inland flooding phenomena, since it will theoretically lead to expanded coverage and deeper water depth of flooded (inundated) areas. Since the direct and indirect impacts of subsidence have also relation among each other, the accurate quantification of the potential losses caused by land subsidence in urban areas is not an easy task to accomplish. The direct losses can be easier to estimate than the indirect losses. For example, the direct losses due to land subsidence in Bandung was estimated to be at least 180 Million USD; but the indirect losses is still unknown.

Using InSAR Remote Sensing Technology to Analyze 3 Basin Aquifer Recharge Areas in Phoenix, Arizona

NASA Astrophysics Data System (ADS)

Smilovsky, D.; Rucker, M. L.

2016-12-01

Land subsidence due to pumping-induced groundwater decline has been well documented in alluviual basins in southern Arizona. Beginning in 2002, satellite-based interferometric synthetic aperture radar (InSAR) began to document post-1992 subsidence across these basins. Several basin aquifer recharge projects using water delivered by the Central Arizona Project (CAP) also began in the early 2000s. Reversal of land subsidence (elastic rebound) associated with recharge is evident in InSAR results across these basins. Projects with rebound documented using InSAR include the Tonopah Desert Recharge Project (permitted 150,000 [ac-ft/yr] starting in 2006) located 40 miles west of Phoenix, and the Hieroglyphic Mountains Recharge Project (permitted 35,000 ac-ft/yr starting in 2003) located several miles north of McMicken Dam in the West Salt River Valley. The Superstition Mountains Recharge Project (ultimate permitting of 85,000 ac-ft/yr, completed in 2011), located at Queen Creek in the East Salt River Valley, has also begun to develop a clear InSAR signature feature. Groundwater level index wells up to several miles downstream from these recharge facilities have indicated groundwater level recoveries of about 70 to 200 feet in the time corresponding to the InSAR studies. Resulting elastic rebound of ground surface elevations due to reduction of effective stresses in the compressible basin alluvium is a function of the effective stress change, the basin alluvium elastic moduli, and the thickness of the effected compressible basin alluvium. The areas and magnitudes of effective stress unloading are indicated from the rebound documented using InSAR. The volumes of aquifer recharge are anticipated to be related to the volumes of InSAR-derived rebound. It is also anticipated that estimates of large-scale horizontal hydraulic conductivity may be approximately verified by areas of ground surface rebound, and gradients driving groundwater flow may be inferred from magnitudes of rebound. These concepts are tested using documented recharge volumes, water level records at index wells, and concurrent InSAR results at the Tonopah and Hieroglyphic Mountains Recharge Projects, and basin alluvium moduli derived from subsidence studies associated with rehabilitation of McMicken Dam.

Heterogeneous Rupture in the Great Cascadia Earthquake of 1700 Inferred from Coastal Subsidence Estimates

NASA Astrophysics Data System (ADS)

Wang, P.; Wang, K.; Hawkes, A.; Horton, B. P.; Engelhart, S. E.; Nelson, A. R.; Witter, R. C.

2011-12-01

Abrupt coastal subsidence induced by the great AD 1700 Cascadia earthquake has been estimated from paleoseismic evidence of buried soils and overlying mud and associated tsunamis deposits. These records have been modeled using a rather uniform rupture model, a mirror image of the uniform interseismic fault locking based on modern GPS observations. However, as seen in other megathrust earthquakes such as at Sumatra, Chile, and Alaska, the rupture must have had multiple patches of concentrated slip. Variable moment release is also seen in the 2011 Tohoku-Oki earthquake in Japan, although there is only one patch. The use of a uniform rupture scenario for Cascadia is due mainly to the poor resolving power of the previous paleoseismic data. In this work, we invoke recently obtained more precise data from detailed microfossil studies to better constrain the slip distribution. Our 3-D elastic dislocation model allows the fault slip to vary along strike. Along any profile in the dip direction, we assume a bell-shaped slip distribution with the peak value scaling with local rupture width, consistent with rupture mechanics. We found that the coseismic slip is large in central Cascadia, and areas of high moment release are separated by areas of low moment release. The amount of slip in northern and southern Cascadia is poorly constrained. Although data uncertainties are large, the coastal variable subsidence can be explained with multiple slip patches. For example, there is an area near Alsea Bay, Oregon (about 44.5°N) that, in accordance with the minimum coseismic subsidence estimated by the microfossil data, had very little slip in the 1700 event. This area approximately coincides with a segment boundary previously defined on the basis of gravity anomalies. There is also reported evidence for the presence of a subducting seamount in this area, and the seamount might be responsible for impeding rupture during large earthquakes. The nature of this rupture barrier and whether it is a persistent feature are important topics of future research. Our results indicate that there is not always a one-to-one correlation between areas of more complete interseismic locking and larger coseismic slip.

Accelerating late Quaternary uplift of the New Georgia Island Group (Solomon island arc) in response to subduction of the recently active Woodlark spreading center and Coleman seamount

NASA Astrophysics Data System (ADS)

Mann, Paul; Taylor, Frederick W.; Lagoe, Martin B.; Quarles, Andrew; Burr, G.

1998-10-01

The New Georgia Island Group of the Solomon Islands is one of four places where an active or recently active spreading ridge has subducted beneath an island arc. We have used coral reef terraces, paleobathymetry of Neogene sedimentary rocks, and existing marine geophysical data to constrain patterns of regional Quaternary deformation related to subduction of the recently active Woodlark spreading center and its overlying Coleman seamount. These combined data indicate the following vertical tectonic history for the central part of the New Georgia Island Group: (1) subsidence of the forearc region (Tetepare and Rendova Islands) to water depths of ˜1500 m and deposition of marine turbidites until after 270 ka; (2) late Quaternary uplift of the forearc to sea level and erosion of an unconformity; (3) subsidence of the forearc to ˜500 m BSL and deposition of bathyal sediments; and (4) uplift of the forearc above sea level with Holocene uplift rates up to at least 7.5 mm/yr on Tetepare and 5 mm/yr on Rendova. In the northeastern part of the New Georgia Island Group, our combined data indicate a slightly different tectonic history characterized by lower-amplitude vertical motions and a more recent change from subsidence to uplift. Barrier reefs formed around New Georgia and Vangunu Islands as they subsided >300 m. By 50-100 ka, subsidence was replaced by uplift that accelerated to Holocene rates of ˜1 mm/yr on the volcanic arc compared with rates up to ˜7.5 mm/yr in the forearc area of Tetepare and Rendova. Uplift mechanisms, such as thermal effects due to subduction of spreading ridges, tectonic erosion, or underplating of deeply subducted bathymetric features, are not likely to function on the 270-ka period that these uplift events have occurred in the New Georgia Island Group. A more likely uplift mechanism for the post-270-ka accelerating uplift of the forearc and volcanic arc of the New Georgia Island Group is progressive impingement of the Coleman seamount or other topographically prominent features on the subducting plate. Regional effects we relate to this ongoing subduction-related process include: (1) late Quaternary (post-270 ka), accelerating uplift of the Rendova-Tetepare forearc area in response to initial impingement of the Coleman seamount followed by exponentially increasing collisional contact between the forearc and seamount; (2) later Quaternary propagation of uplift arcward to include the volcanic arc as the area of collisional contact between the forearc and seamount increased; and (3) large-wavelength folding that has produced regional variations in late Holocene uplift rates observed in both forearc (southern Rendova, Tetepare) and volcanic arc (New Georgia Island) areas. We propose that the dominant tectonic effect of Coleman seamount impingement is horizontal shortening of the forearc and arc crust that is produced by strong coupling between the subducting seamount and the unsedimented crystalline forearc of the New Georgia Island Group. The horizontal forces due to mechanical resistance to subducting rugged ridge and seamount topography may have terminated spreading of the Woodlark spreading center entering the trench (Ghizo ridge) and converted it to a presently active strike-slip fault zone.

Soil-related geohazard assessments for maintaining the UK's minor road network

NASA Astrophysics Data System (ADS)

Pritchard, Oliver; Hallett, Stephen; Farewell, Timothy

2015-04-01

The minor road network of the UK (United Kingdom) encompasses 98% of the overall road network. In recent years the UK's roads have been deteriorating, currently rated 26th in the world and considered at risk and declining by the Institution of Civil Engineers (ICE). Many factors contribute to the degradation and ultimately, to the failure of particular road sections. However, several UK local authorities have identified that during drought conditions, road sections founded upon clay soils which are susceptible to volumetric shrinkage and swelling undergo significant deterioration compared to those sections on non-susceptible soils. Droughts in East Anglia recently resulted in estimated damages of £26 million, leading several local authorities to apply to Central Government for emergency funding. The minor or evolved road network is most at risk due to them having often little, if any, structural foundations. This paper addresses the use of soil-related geohazard assessments and GIS (Geographical Information Systems) in helping to provide a soil-informed maintenance strategy for the asset management of the important (both socially and commercially) local road network of the UK. Furthermore, to establish future subsidence risk, UKCP09 climate projections have been used to model the likely potential soil moisture deficit (PSMD) for baseline (1961-1990), 2030 (2020-2049) and 2050 (2040-2069) scenarios. The incorporation of probabilistic PSMD data into clay-related subsidence models has allowed an assessment of potential subsidence risk, with a range of uncertainties, for these scenarios. Intersection of road networks with future projections of subsidence risk has enabled metrics of potential vulnerability to be established. This will aid prioritisation of areas which require further maintenance to make them more climate resilient, avoiding emergency funding situations. Subsequently, this approach can then be extrapolated to the entire UK minor road network, on a local authority level, to provide a series of regional risk assessments. Case studies are drawn from the UK administrative counties of Lincolnshire and Worcestershire. Data from observed road assessments, obtained from the respective local authorities have been analysed and intersected with clay-related subsidence risk. Lincolnshire County Council have already implemented this research to prioritise approximately £600,000 of road maintenance fund to their minor road network. Further appreciation of the spatial distribution and understanding of soil-related hazards has also led Lincolnshire County Council to trial new resurfacing strategies; these new techniques helping to reduce carbon outputs in the form of materials and transport. A reduction in the amount of potential hazardous (bituminous) waste to landfill is also being achieved through re-inclusion of waste material back into the road foundation where areas are particularly prone to soil shrinkage. Our research shows that soil-related geohazard assessments have a part to play in the asset management of the UK's local highways network. The study supports the ICE's recommendation for a regime which moves towards planned, preventative maintenance and achieving Defra's (Department for Environment, Food and Rural Affairs) aim of a climate resilient UK infrastructure. The methodology introduced here also has applicability to other countries, where appropriate soils and infrastructure data are available.

Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor.

PubMed

Kivell, Tracy L; Schmitt, Daniel

2009-08-25

Despite decades of debate, it remains unclear whether human bipedalism evolved from a terrestrial knuckle-walking ancestor or from a more generalized, arboreal ape ancestor. Proponents of the knuckle-walking hypothesis focused on the wrist and hand to find morphological evidence of this behavior in the human fossil record. These studies, however, have not examined variation or development of purported knuckle-walking features in apes or other primates, data that are critical to resolution of this long-standing debate. Here we present novel data on the frequency and development of putative knuckle-walking features of the wrist in apes and monkeys. We use these data to test the hypothesis that all knuckle-walking apes share similar anatomical features and that these features can be used to reliably infer locomotor behavior in our extinct ancestors. Contrary to previous expectations, features long-assumed to indicate knuckle-walking behavior are not found in all African apes, show different developmental patterns across species, and are found in nonknuckle-walking primates as well. However, variation among African ape wrist morphology can be clearly explained if we accept the likely independent evolution of 2 fundamentally different biomechanical modes of knuckle-walking: an extended wrist posture in an arboreal environment (Pan) versus a neutral, columnar hand posture in a terrestrial environment (Gorilla). The presence of purported knuckle-walking features in the hominin wrist can thus be viewed as evidence of arboreality, not terrestriality, and provide evidence that human bipedalism evolved from a more arboreal ancestor occupying the ecological niche common to all living apes.

Subsidence (2004-2009) in and near lakebeds of the Mojave River and Morongo groundwater basins, southwest Mojave Desert, California

USGS Publications Warehouse

Solt, Mike; Sneed, Michelle

2014-01-01

Subsidence, in the vicinity of dry lakebeds, within the Mojave River and Morongo groundwater basins of the southwest Mojave Desert has been measured by Interferometric Synthetic Aperture Radar (InSAR). The investigation has focused on determining the location, extent, and magnitude of changes in land-surface elevation. In addition, the relation of changes in land-surface elevation to changes in groundwater levels and lithology was explored. This report is the third in a series of reports investigating land-surface elevation changes in the Mojave and Morongo Groundwater Basins, California. The first report, U.S. Geological Survey (USGS) Water-Resources Investigations Report 03-4015 by Sneed and others (2003), describes historical subsidence and groundwater-level changes in the southwest Mojave Desert from 1969 to 1999. The second report, U.S. Geological Survey Water-Resources Investigations Report 07-5097, an online interactive report and map, by Sneed and Brandt (2007), describes subsidence and groundwater-level changes in the southwest Mojave Desert from 1999 to 2004. The purpose of this report is to document an updated assessment of subsidence in these lakebeds and selected neighboring areas from 2004 to 2009 as measured by InSAR methods. In addition, continuous Global Positioning System (GPS)(2005-10), groundwater level (1951-2010), and lithologic data, if available, were used to characterize compaction mechanisms in these areas. The USGS California Water Science Center’s interactive website for the Mojave River and Morongo groundwater basins was created to centralize information pertaining to land subsidence and water levels and to allow readers to access available data and related reports online. An interactive map of land subsidence and water levels in the Mojave River and Morongo groundwater basins displays InSAR interferograms, subsidence areas, subsidence contours, hydrographs, well information, and water-level contours. Background information, including a basic description of the mechanics of land subsidence and InSAR, as well as a description of the study area, is presented within the Mojave Water Resources Interactive Map and report.

Groundwater Regulation in the Houston-Galveston Region to Control Subsidence - Balancing Total Water Demand, Available Alternative Water Supplies, and Groundwater Withdrawal

NASA Astrophysics Data System (ADS)

Turco, M. J.

2014-12-01

In 1975, as a result of area residents and local governments becoming increasingly alarmed by the continued impact of subsidence on economic growth and quality of life in the region, the Harris-Galveston Coastal Subsidence District was created by the 64th Texas Legislature as an underground water conservation district. The primary mission of what is now the Harris-Galveston Subsidence District, is to provide for the regulation of the withdrawal of groundwater to control subsidence. Subsidence has been a concern in the Houston, TX area throughout most of recent history. Since 1906, over 10 feet of subsidence has occurred, with a broad area of 6 feet of subsidence throughout most of the Houston Area.Over its nearly forty years of existence, the District has developed substantial data sets providing the foundation for its regulatory plan. Annual water-level measurements, a network of deep extensometers, over 80 subsidence GPS monitors, and updated numerical and analytical models have been utilized. Periodically, the District utilizes U.S. Census data to predict the future magnitude and location of population and water demand. In 2013, all of these data sets were combined producing an updated regulatory plan outlining the timelines of conversion to alternative sources of water and defining the maximum percentage groundwater can contribute to a user's total water demand.The management of the groundwater resources within the District has involved significant coordination with regional ground and surface water suppliers; ongoing interaction with other state and local regulatory bodies; analysis of accurate and up to date predictions on water usage; the enforcement of real disincentives to those who rely too heavily on groundwater and a commitment to practicing and promoting water conservation.Water supplies in the region are projected to continue to be stressed in the future due to rapid population increases in the region. Future District efforts will be focused on maintaining the successes of the past while evaluating potential deeper groundwater resources and any potential subsidence resulting from future development.

Pathways as a tool for the governance of sustainable management of soilsubsidence

NASA Astrophysics Data System (ADS)

Ellen, G. J.; Hommes, S.

2017-12-01

Subsidence is a physical, societal, economic and institutional challenge for the Netherlands. For urban areas because subsidence threatens the nearby future the liveability and touristic attractiveness of the historic cities. For the rural areas because it affects the - intensive - agricultural landuse which is an important pilar of the Dutch economy. Policy and decision-making concerning subsidence is suffering from `non-decision making'. Subsidence has been described and mapped based on (geological and geotechnical) scientific research, but the subject has only been marginally addressing in the national, regional and local policy arena's. To actually make it possible for subsidence to be discussed in the policy arena a method was designed which was used in two cases : the Dutch city of Gouda and a more rural area in the province of Flevoland in the middle of the Netherlands. The method used was based on three building blocks. First of all future perspectives - scenario planning methodology was used to create future perspectives on coping with land subsidence. For example for Gouda we created 4 future perspectives for 2060 distinguishing between allocation of responsibilities (public or private) and the strategic decision to cope with land subsidence (halt or continue to sink). The second building block was the use of pathways, were each pathway consisted of a cluster of land subsidence strategies covering the many dimensions of land subsidence, ranging from houses and their foundations for the city of Gouda towards different types of agricultural land use for the rural area in the province of Flevoland. The last building block was a governance design approach were for every pathway a governance arrangements were designed together with stakeholders. The method was evaluated and proved to be very useful. First, a better understanding of the unsustainability of subsidence was obtained. In addition, the different perspectives and strategies stimulated discussions within the policy arena's on what might be needed especially in terms of governance. Finally, after applying the described method a higher awareness has been gained on `non-decision making' and ways to move forward.

Subsidence Induced Faulting Hazard risk maps in Mexico City and Morelia, central Mexico

NASA Astrophysics Data System (ADS)

Cabral-Cano, E.; Solano-Rojas, D.; Hernández-Espriu, J.; Cigna, F.; Wdowinski, S.; Osmanoglu, B.; Falorni, G.; Bohane, A.; Colombo, D.

2012-12-01

Subsidence and surface faulting have affected urban areas in Central Mexico for decades and the process has intensified as a consequence of urban sprawl and economic growth. This process causes substantial damages to the urban infrastructure and housing structures and in several cities it is becoming a major factor to be considered when planning urban development, land use zoning and hazard mitigation strategies in the next decades. Subsidence is usually associated with aggressive groundwater extraction rates and a general decrease of aquifer static level that promotes soil consolidation, deformation and ultimately, surface faulting. However, local stratigraphic and structural conditions also play an important role in the development and extension of faults. Despite its potential for damaging housing, and other urban infrastructure, the economic impact of this phenomena is poorly known, in part because detailed, city-wide subsidence induced faulting risk maps have not been published before. Nevertheless, modern remote sensing techniques are most suitable for this task. We present the results of a risk analysis for subsidence induced surface faulting in two cities in central Mexico: Morelia and Mexico City. Our analysis in Mexico City and Morelia is based on a risk matrix using the horizontal subsidence gradient from a Persistent Scatterer InSAR (Morelia) and SqueeSAR (Mexico City) analysis and 2010 census population distribution data from Mexico's National Institute of Statistics and Geography. Defining subsidence induced surface faulting vulnerability within these urbanized areas is best determined using both magnitude and horizontal subsidence gradient. Our Morelia analysis (597,000 inhabitants with localized subsidence rates up to 80 mm/yr) shows that 7% of the urbanized area is under a high to very high risk level, and 14% of its population (11.7% and 2.3% respectively) lives within these areas. In the case of the Mexico City (15'490,000 inhabitants for the Mexico city Metropolitan area included within our map, and up to 370 mm/yr subsidence rate) our risk map shows that 13.5% of the urbanized area is under a high to very high risk level, and 26.2% of its population (22.1% and 4.4% respectively) lives within these areas.

Stewardship of the Evolving Scholarly Record: From the Invisible Hand to Conscious Coordination

ERIC Educational Resources Information Center

Lavoie, Brian; Malpas, Constance

2015-01-01

The long-term future of the scholarly record in its fullest expression cannot be effectively secured with stewardship strategies designed for print materials. The features of the evolving scholarly record suggest that traditional stewardship strategies, built on an "invisible hand" approach that relies on the uncoordinated,…

Did Language Evolve Like the Vertebrate Eye?

ERIC Educational Resources Information Center

Botha, Rudolf P.

2002-01-01

Offers a critical appraisal of the way in which the idea that human language or some of its features evolved like the vertebrate eye by natural selection is articulated in Pinker and Bloom's (1990) selectionist account of language evolution. Argues that this account is less than insightful because it fails to draw some of the conceptual…

Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.

PubMed

Grant, Tanner W; Lovro, Luke R; Licini, David J; Warth, Lucian C; Ziemba-Davis, Mary; Meneghini, Robert M

2017-03-01

Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs. A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs. Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013). An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Land subsidence in the San Joaquin Valley, California, USA, 2007-2014

NASA Astrophysics Data System (ADS)

Sneed, M.; Brandt, J. T.

2015-11-01

Rapid land subsidence was recently measured using multiple methods in two areas of the San Joaquin Valley (SJV): between Merced and Fresno (El Nido), and between Fresno and Bakersfield (Pixley). Recent land-use changes and diminished surface-water availability have led to increased groundwater pumping, groundwater-level declines, and land subsidence. Differential land subsidence has reduced the flow capacity of water-conveyance systems in these areas, exacerbating flood hazards and affecting the delivery of irrigation water. Vertical land-surface changes during 2007-2014 were determined by using Interferometric Synthetic Aperture Radar (InSAR), Continuous Global Positioning System (CGPS), and extensometer data. Results of the InSAR analysis indicate that about 7600 km2 subsided 50-540 mm during 2008-2010; CGPS and extensometer data indicate that these rates continued or accelerated through December 2014. The maximum InSAR-measured rate of 270 mm yr-1 occurred in the El Nido area, and is among the largest rates ever measured in the SJV. In the Pixley area, the maximum InSAR-measured rate during 2008-2010 was 90 mm yr-1. Groundwater was an important part of the water supply in both areas, and pumping increased when land use changed or when surface water was less available. This increased pumping caused groundwater-level declines to near or below historical lows during the drought periods 2007-2009 and 2012-present. Long-term groundwater-level and land-subsidence monitoring in the SJV is critical for understanding the interconnection of land use, groundwater levels, and subsidence, and evaluating management strategies that help mitigate subsidence hazards to infrastructure while optimizing water supplies.

Water availability and land subsidence in the Central Valley, California, USA

NASA Astrophysics Data System (ADS)

Faunt, Claudia C.; Sneed, Michelle; Traum, Jon; Brandt, Justin T.

2016-05-01

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007-2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

Study on the risk and impacts of land subsidence in Jakarta

NASA Astrophysics Data System (ADS)

Abidin, H. Z.; Andreas, H.; Gumilar, I.; Brinkman, J. J.

2015-11-01

Jakarta is the capital city of Indonesia located in the west-northern coast of Java island, within a deltaic plain and passes by 13 natural and artificial rivers. This megapolitan has a population of about 10.2 million people inhabiting an area of about 660 km2, with relatively rapid urban development. It has been reported for many years that several places in Jakarta are subsiding at different rates. The main causative factors of land subsidence in Jakarta are most probably excessive groundwater extraction, load of constructions (i.e., settlement of high compressibility soil), and natural consolidation of alluvial soil. Land subsidence in Jakarta has been studied using leveling surveys, GPS surveys, InSAR and Geometric-Historic techniques. The results obtained from leveling surveys, GPS surveys and InSAR technique over the period between 1974 and 2010 show that land subsidence in Jakarta has spatial and temporal variations with typical rates of about 3-10 cm year-1. Rapid urban development, relatively young alluvium soil, and relatively weak mitigation and adapatation initiatives, are risk increasing factors of land subsidence in Jakarta. The subsidence impacts can be seen already in the field in forms of cracking and damage of housing, buildings and infrastructure; wider expansion of (riverine and coastal) flooding areas, malfunction of drainage system, changes in river canal and drain flow systems and increased inland sea water intrusion. These impacts can be categorized into infrastructural, environmental, economic and social impacts. The risk and impacts of land subsidence in Jakarta and their related aspects are discussed in this paper.

Water availability and land subsidence in the Central Valley, California, USA

USGS Publications Warehouse

Faunt, Claudia; Sneed, Michelle; Traum, Jonathan A.; Brandt, Justin

2016-01-01

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

Investigation of Land Subsidence using ALOS PALSAR data: a case study in Mentougou (Beijing, China)

NASA Astrophysics Data System (ADS)

Chen, Jianping; Xiang, Jie; Xie, Shuai; Liu, Jing; Tarolli, Paolo

2017-04-01

Mining activities have been documented for centuries in Mentougou, and land subsidence resulting from mining operations has already been known over the past few decades. However, there has been ongoing concern that excessive groundwater extraction may lead to further subsidence. Therefore it is critical to map the land cover changes to understand the actual impact of these activities. So, the land cover changes from 2006 to 2011 were examined based on multi-source remote sensing imageries( including ALOS and landsat-7) by using object-oriented classifications combined with a decision tree and retrospective approaches. Also, land subsidence in Mentougou between 2006 and 2011 has been mapped using the interferometric synthetic aperture radar (InSAR) time-series analysis with the ALOS L-band SAR data. We processed 14 ascending SAR images during May 2006 to July 2011. Comparison of InSAR measurements with the land cover changes and pre-existing faults suggest that mining activities is the main cause of land subsidence. The land subsidence observed from InSAR data are approximately up to 15 mm/year in open-pit mining area and up to 24 mm/year in underground mining areas. The InSAR result are validated by the ground survey data in several areas, and the comparison between the InSAR result with the mining schedule showed there were some correlations between them. The result underline the potential use of InSAR measurements to provide better investigation for land subsidence, and also suggest that the most influential factors for land subsidence is underground coal mine.

Fragmentary evidence of great-earthquake subsidence during holocene emergence, Valdivia estuary, South Central Chile

USGS Publications Warehouse

Nelson, A.R.; Kashima, K.; Bradley, L.A.

2009-01-01

A reconnaissance of Holocene stratigraphy beneath fringing marshes of the Valdivia estuary, where an M 9.5 earthquake caused 1-2 m of regional coseismic subsidence in 1960, shows only fragmentary evidence of prehistoric coseismic subsidence. In most of the 150 hand-driven cores that were examined, a distinct unconformity separates 0.5-1.5 m of late Holocene tidal and floodplain mud, peat, and sand from underlying middle Holocene subtidal mud and sand. At the Las Coloradas site, where stratigraphy is best preserved, two A horizons of marsh and meadow soils abruptly overlain by sand and mud probably record coseismic subsidence shortly followed by tsunamis. The amount of subsidence during the earthquakes proved difficult to reconstruct with a diatom transfer function because of differences between modern and fossil diatom assemblages. Maximum 14C ages on macrofossils from the two A horizons at the Las Coloradas site of 1.7-1.3 ka and 2.7-1.7 ka allow correlation of the younger horizon with either of two of six 14C-dated A horizons buried by tsunami sand or post-tsunami tidal sand 200 km to the south at Maull??n, and with a lake-wide mass wasting event in Lago Puyehue, 100 km to the southeast. Tidal records of prehistoric coseismic subsidence at Valdivia are scarce because of a sea-level fall of 3-8 m over the past 6000 years, erosion of marsh and meadow soils during subsidence-induced flooding of the estuary, and largely complete land-level recovery during cycles of coseismic subsidence and postseismic uplift.

The Evolving Role of Chemical Synthesis in Antibacterial Drug Discovery

PubMed Central

Wright, Peter M.; Seiple, Ian B.; Myers, Andrew G.

2015-01-01

The discovery and implementation of antibiotics in the early twentieth century transformed human health and wellbeing. Chemical synthesis enabled the development of the first antibacterial substances, organoarsenicals and sulfa drugs, but these were soon outshone by a host of more powerful and vastly more complex antibiotics from nature: penicillin, streptomycin, tetracycline, and erythromycin, among others. These primary defences are now significantly less effective as an unavoidable consequence of rapid evolution of resistance within pathogenic bacteria, made worse by widespread misuse of antibiotics. For decades medicinal chemists replenished the arsenal of antibiotics by semisynthetic and to a lesser degree fully synthetic routes, but economic factors have led to a subsidence of this effort, which places society on the precipice of a disaster. We believe that the strategic application of modern chemical synthesis to antibacterial drug discovery must play a critical role if a crisis of global proportions is to be averted. PMID:24990531

Thermally-driven subsidence of large platformal basins: linking growth of the lithosphere subsidence patterns on the surface

NASA Astrophysics Data System (ADS)

Holt, P.; Allen, M. B.; Van Hunen, J.

2012-04-01

A large number of areas which have experienced platformal subsidence during the Phanerozoic are located upon regions of juvenile accretionary crust. These include the Palaeozoic basins of North Africa, the Paraná and Parnaíba basins in South America, the Cape-Karoo basin in South Africa, the Mesozoic Scythian and Turan platforms in Central Asia and the Eastern Australian basins. We hypothesise that the juvenile accretionary crust is initially underlain by a thin mantle lithosphere. This is most likely inherited from the island arcs, accretionary prisms and microcontinents that collided to form this juvenile crust, although it could also be due to lithospheric delamination as a result of the collision. Once the crust has stabilised the lithosphere begins to cool and thicken, which drives the observed subsidence. To test this we constructed a simple 1D forward finite difference model which calculates heat conduction through a column of crust, mantle lithosphere and upper mantle as it cools. The model then isostatically calculates the water loaded subsidence produced by this process. This allows us to use subsidence curves calculated from the sedimentary record preserved within the basin to test whether the basins could be forming in response to growth of the lithosphere. The results from the model showed that the subsidence produced was most sensitive to variations in crustal thickness and plate thickness (final lithospheric thickness). The modelled subsidence curves were then compared to subsidence curves acquired by backstripping the sediments within the basins mentioned above. The parameters were varied iteratively to find the best fit between the modelled and the observed subsidence. This produced good fits and also provided another method to validate the model results. The crustal thickness and final lithospheric thickness from the models were then compared to measurements of these parameters from other sources such as deep seismic lines and tomographic imaging of the Low Velocity Zone. These generally agreed well with the values used in the model and were used to further constrain the model. However, subsidence of thin lithosphere is not necessarily limited to unmodified accretionary crust, as described above. For instance the subsidence of the West Siberian Basin, outside the rift system, is similar to the platformal basins mentioned above except that there is a delay of 50 - 90 Myrs between the rifting (and associated eruption of the Siberian flood basalts), and the onset of sedimentation. We used a variant of our model that incorporated an anomalously hot layer beneath a thinned lithosphere to represent a cooling mantle plume head. This produced a good match to the subsidence patterns from the West Siberian Basin. This coupling of deep processes with surface processes allows us to further understand how the basins form, but inversely the sedimentary record could be used to investigate the growth of the lithosphere and provide a prediction of present day lithospheric thickness independent of seismic methods.

50 CFR 600.1005 - Content of a request for a subsidized program.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Content of a request for a subsidized program. 600.1005 Section 600.1005 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... subsidized program shall: (a) Specify the reduction fishery. (b) Project the amount of the reduction and...

50 CFR 600.1005 - Content of a request for a subsidized program.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Content of a request for a subsidized program. 600.1005 Section 600.1005 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... subsidized program shall: (a) Specify the reduction fishery. (b) Project the amount of the reduction and...

50 CFR 600.1005 - Content of a request for a subsidized program.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Content of a request for a subsidized program. 600.1005 Section 600.1005 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... subsidized program shall: (a) Specify the reduction fishery. (b) Project the amount of the reduction and...

50 CFR 600.1005 - Content of a request for a subsidized program.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Content of a request for a subsidized program. 600.1005 Section 600.1005 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... subsidized program shall: (a) Specify the reduction fishery. (b) Project the amount of the reduction and...

Subsidizing Private Education at Taxpayer Expense. Policy Brief

ERIC Educational Resources Information Center

National Education Association, 2017

2017-01-01

Efforts to subsidize private education take a variety of forms, with the most familiar being the private school voucher provided directly to parents. But there are other less direct ways governments subsidize private schools. One such method is to provide a tax credit to parents to offset their personal education expenses (education tax credit).…

24 CFR 982.504 - Voucher tenancy: Payment standard for family in restructured subsidized multifamily project.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Voucher tenancy: Payment standard for family in restructured subsidized multifamily project. 982.504 Section 982.504 Housing and Urban...: Payment standard for family in restructured subsidized multifamily project. (a) This section applies to...

24 CFR 982.504 - Voucher tenancy: Payment standard for family in restructured subsidized multifamily project.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Voucher tenancy: Payment standard for family in restructured subsidized multifamily project. 982.504 Section 982.504 Housing and Urban...: Payment standard for family in restructured subsidized multifamily project. (a) This section applies to...

24 CFR 982.504 - Voucher tenancy: Payment standard for family in restructured subsidized multifamily project.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Voucher tenancy: Payment standard for family in restructured subsidized multifamily project. 982.504 Section 982.504 Housing and Urban...: Payment standard for family in restructured subsidized multifamily project. (a) This section applies to...

24 CFR 982.504 - Voucher tenancy: Payment standard for family in restructured subsidized multifamily project.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Voucher tenancy: Payment standard for family in restructured subsidized multifamily project. 982.504 Section 982.504 Housing and Urban...: Payment standard for family in restructured subsidized multifamily project. (a) This section applies to...

Earth fissures and localized differential subsidence

USGS Publications Warehouse

Holzer, Thomas L.; Pampeyan, Earl Haig

1979-01-01

Long tension cracks caused by declines of ground-water level at four sites in Arizona, California, and Nevada occur at points of maximum, convex-upward curvature in subsidence profiles based on relevelings of closely-spaced bench marks aligned perpendicular to the cracks. We conclude the cracks are caused by horizontal strains associated with the differential subsidence.

30 CFR 817.121 - Subsidence control.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...

30 CFR 817.121 - Subsidence control.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...

30 CFR 817.121 - Subsidence control.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...

30 CFR 817.121 - Subsidence control.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...

30 CFR 817.121 - Subsidence control.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Subsidence control. 817.121 Section 817.121... ACTIVITIES § 817.121 Subsidence control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...

Monitoring and modeling of sinkhole-related subsidence in west-central Florida mapped from InSAR and surface observations

NASA Astrophysics Data System (ADS)

Kiflu, H.; Oliver-Cabrera, T.; Robinson, T.; Wdowinski, S.; Kruse, S.

2017-12-01

Sinkholes in Florida cause millions of dollars in damage to infrastructure each year. Methods of early detection of sinkhole-related subsidence are clearly desirable. We have completed two years of monitoring of selected sinkhole-prone areas in west central Florida with XXX data and analysis with XXX algorithms. Filters for selecting targets with high signal-to-noise ratio and subsidence over this time window (XX-2015-XX-2017) are being used to select sites for ground study. A subset of the buildings with InSAR-detected subsidence indicated show clear structural indications of subsidence in the form of cracks in walls and roofs. Comsol Multiphysics models have been developed to describe subsidence at the rates identified from the InSAR analysis (a few mm/year) and on spatial scales observed from surface observations, including structural deformation of buildings and ground penetrating radar images of subsurface deformation (length scales of meters to tens of meters). These models assume cylindrical symmetry and deformation of elastic and poroelastic layers over a growing sphering void.

Analysis and simulation of regional subsidence accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA

USGS Publications Warehouse

Galloway, Devin L.; Sneed, Michelle

2013-01-01

Regional aquifer-system compaction and land subsidence accompanying groundwater abstraction in susceptible aquifer systems in the USA is a challenge for managing groundwater resources and mitigating associated hazards. Developments in the assessment of regional subsidence provide more information to constrain analyses and simulation of aquifer-system compaction. Current popular approaches to simulating vertical aquifer-system deformation (compaction), such as those embodied in the aquitard drainage model and the MODFLOW subsidence packages, have proven useful from the perspective of regional groundwater resources assessment. However, these approaches inadequately address related local-scale hazards—ground ruptures and damages to engineered structures on the land surface arising from tensional stresses and strains accompanying groundwater abstraction. This paper presents a brief overview of the general approaches taken by the U.S. Geological Survey toward understanding aquifer-system compaction and subsidence with regard to a) identifying the affected aquifer systems; b) making regional assessments; c) analyzing the governing processes; and d) simulating historical and future groundwater flow and subsidence conditions. Limitations and shortcomings of these approaches, as well as future challenges also are discussed.

Clinical evaluation and radiographic assessment of bone lysis of the AES total ankle replacement.

PubMed

Besse, Jean-Luc; Brito, Nuno; Lienhart, Christophe

2009-10-01

AES mobile-bearing total ankle replacement is evolved from the Buechel Pappas model. We report medium-term results of a prospective study with AES. All patients who underwent AES TAR for ankle arthritis, by a single surgeon, from 2003 to 2006 were included, excluding neurologic disease, talar osteonecrosis and malalignment more than 20 degrees. All were reviewed at 6 months, 1 year, and at yearly intervals thereafter. X-rays were analyzed by three observers, using a 10-zone protocol. Fifty consecutive AES implants in 47 patients (mean age, 56 years; range, 21 to 79 year) were included, with at least 2 years' followup (mean 40 months). Preoperative diagnosis was mainly post-traumatic (50%) and osteoarthritis secondary to instability (36%). Associated procedures were performed in 38%. Eighty-two percent had good functional results. The mean AOFAS score rose from 36.9 +/- 1.7 preoperatively to 85.4 +/- 12, dorsiflexion from 3 degrees to 7.3 degrees, and plantarflexion from 30.8 degrees to 37.8 degrees. Two ankles underwent secondary arthrodesis for talar subsidence and mechanical dislocation. Ninety-eight percent of implants were well positioned at 90 degrees +/-4. Mean prosthesis ROM on X-ray was 22.1 degrees. There were tibia/implant interface cysts (greater than 5 mm) in 62% of cases, and talar/implant interface cysts in 43%. Although functional outcomes were comparable to the other mobile TAR in the literature, bone lysis with the AES prosthesis was more frequent with risk of subsidence. We therefore stopped implantation of this prosthesis and recommend preventive grafting for severe lysis.

Asymmetric Effects of Subaerial and Subaqueous Basement Slopes on Self-Similar Morphology of Prograding Deltas

NASA Astrophysics Data System (ADS)

Lai, Steven Yueh Jen; Hsiao, Yung-Tai; Wu, Fu-Chun

2017-12-01

Deltas form over basements of various slope configurations. While the morphodynamics of prograding deltas over single-slope basements have been studied previously, our understanding of delta progradation over segmented basements is still limited. Here we use experimental and analytical approaches to investigate the deltaic morphologies developing over two-slope basements with unequal subaerial and subaqueous slopes. For each case considered, the scaled profiles of the evolving delta collapse to a single profile for constant water and sediment influxes, allowing us to use the analytical self-similar profiles to investigate the individual effects of subaerial/subaqueous slopes. Individually varying the subaerial/subaqueous slopes exerts asymmetric effects on the morphologies. Increasing the subaerial slope advances the entire delta; increasing the subaqueous slope advances the upstream boundary of the topset yet causes the downstream boundary to retreat. The delta front exhibits a first-retreat-then-advance migrating trend with increasing subaqueous slope. A decrease in subaerial topset length is always accompanied by an increase in subaqueous volume fraction, no matter which segment is steepened. Applications are presented for estimating shoreline retreat caused by steepening of basement slopes, and estimating subaqueous volume and delta front using the observed topset length. The results may have implications for real-world delta systems subjected to upstream tectonic uplift and/or downstream subsidence. Both scenarios would exhibit reduced topset lengths, which are indicative of the accompanied increases in subaqueous volume and signal tectonic uplift and/or subsidence that are at play. We highlight herein the importance of geometric controls on partitioning of sediment between subaerial and subaqueous delta components.

The Inconvenient Truth of Fresh Sediment: Insights from a New Method for Quantifying Subsidence in the Mississippi Delta

NASA Astrophysics Data System (ADS)

Chamberlain, E. L.; Shen, Z.; Tornqvist, T. E.; Kim, W.

2017-12-01

Knowing the rates and drivers of subsidence in deltas is essential to coastal management. There is a growing consensus that relatively shallow processes such as compaction and artificial drainage are primary contributors to subsidence, although deeper processes such as faulting may be locally important. Here we present a new method to quantify subsidence of a 6000 km2 relict bayhead delta of the Mississippi Delta, using the depth of the mouthbar-overbank stratigraphic boundary that formed near the low tide level in combination with OSL chronology. The contributions of isostatic processes are removed by subtracting a relative sea-level rise term previously obtained from basal peat. We find that displacement rates of the boundary, averaged over 750 to 1500 years, are on the order of a few mm/yr. Cumulative displacement is strongly correlated to overburden thickness, decreases coastward coincident with thinning of the bayhead delta deposit, and appears unrelated to the thickness of underlying Holocene strata or the occurrence of previously mapped faults. This supports compaction of shallow strata as a dominant driver of subsidence in the Mississippi Delta. We find that at least 50% of elevation gained through overbank deposition is ultimately lost to subsidence, significantly greater than the 35% loss previously estimated for inland localities underlain by peat. Our results demonstrate that bayhead deltas are especially vulnerable to subsidence. This finding has major relevance to coastal restoration in the Mississippi Delta through engineered river-sediment diversions. While inactive regions of the delta may be fairly stable if not perturbed by humans, the introduction of fresh sediment to the delta plain will inevitably accelerate subsidence. Values obtained with our method will be applied to a delta growth model that predicts the land-building potential of river-sediment diversions discharging into open bays under realistic scenarios of load-driven subsidence.

An integrated application of SAR interferometry and GRACE solution to land subsidence in a rapidly urbanizing groundwater dependent basin in Pakistan

NASA Astrophysics Data System (ADS)

Ahmad, Waqas; Kim, Soohyun; Kim, Dongkyun

2017-04-01

Land subsidence and crustal deformation associated with groundwater abstraction is a gradually instigating phenomenon. The exploitation of Interferometric Synthetic Aperture Radar (InSAR) for land subsidence velocity and the Gravity Recovery and Climate Experiment (GRACE) for change in groundwater storage have great potential besides other applications to address this problem. In this paper we used an integrated approach to combine InSAR and GRACE solutions to show that land subsidence velocity in a rapidly urbanizing and groundwater dependent basin in Pakistan is largely attributed to over exploitation of groundwater aquifer. We analyzed a total of 28 Sentinel-1 based interferograms generated for the period October 2014 to November 2016 to quantify the level of land subsidence in the study area. To increase the accuracy of our interferometry results we then applied a filter of Amplitude Dispersion Index (ADI) to confine the spatial extent of land subsidence to persistently scattering pixels. For the GRACE experiment we take the average of change in Total Water Storage (TWS) solutions provided by the Center for Space Research (CSR), the German Research Centre for Geosciences (GFZ), and the Jet Propulsion Laboratory (JPL) and validate this mean TWS for the study area using a network of observed time series groundwater levels. The validation result of GRACE TWS field shows that although the GRACE foot print is spatially larger than the extent of the study area but significant change in water storage can contribute to the overall trend of declining water storage. Finally we compared our results of InSAR land subsidence velocities and GRACE TWS change field. A strong dependence of the land subsidence on the temporal change in TWS suggests that most of the land subsidence could be attributed to the unchecked exploitation of groundwater aquifer.

Is the radiographic subsidence of stand-alone cages associated with adverse clinical outcomes after cervical spine fusion? An observational cohort study with 2-year follow-up outcome scoring.

PubMed

Zajonz, Dirk; Franke, Anne-Catherine; von der Höh, Nicolas; Voelker, Anna; Moche, Michael; Gulow, Jens; Heyde, Christoph-Eckhard

2014-01-01

The stand-alone treatment of degenerative cervical spine pathologies is a proven method in clinical practice. However, its impact on subsidence, the resulting changes to the profile of the cervical spine and the possible influence of clinical results compared to treatment with additive plate osteosynthesis remain under discussion until present. This study was designed as a retrospective observational cohort study to test the hypothesis that radiographic subsidence of cervical cages is not associated with adverse clinical outcomes. 33 cervical segments were treated surgically by ACDF with stand-alone cage in 17 patients (11 female, 6 male), mean age 56 years (33-82 years), and re-examined after eight and twenty-six months (mean) by means of radiology and score assessment (Medical Outcomes Study Short Form (MOS-SF 36), Oswestry Neck Disability Index (ONDI), painDETECT questionnaire and the visual analogue scale (VAS)). Subsidence was observed in 50.5% of segments (18/33) and 70.6% of patients (12/17). 36.3% of cases of subsidence (12/33) were observed after eight months during mean time of follow-up 1. After 26 months during mean time of follow-up 2, full radiographic fusion was seen in 100%. MOS-SF 36, ONDI and VAS did not show any significant difference between cases with and without subsidence in the two-sample t-test. Only in one type of scoring (painDETECT questionnaire) did a statistically significant difference in t-Test emerge between the two groups (p = 0.03; α = 0.05). However, preoperative painDETECT score differ significantly between patients with subsidence (13.3 falling to 12.6) and patients without subsidence (7.8 dropped to 6.3). The radiological findings indicated 100% healing after stand-alone treatment with ACDF. Subsidence occurred in 50% of the segments treated. No impact on the clinical results was detected in the medium-term study period.

Adaptation and mitigation of land subsidence in Semarang

NASA Astrophysics Data System (ADS)

Andreas, Heri; Abidin, Hasanuddin Z.; Gumilar, Irwan; Sidiq, Teguh Purnama; Yuwono, Bambang

2017-07-01

Land subsidence is not a new phenomenon for Semarang. Some report said the subsidence in Semarang probably is occurring for more than 100 years. Based on the leveling surveys conducted by the Centre of Environmental Geology from 1999 to 2003 it was found that relatively large subsidence was detected around Semarang Harbor, Pondok Hasanuddin, Bandar Harjo and around Semarang Tawang Railway station, with the rates ranging from 1 to 17 cm/year. Results derived from GPS show that land subsidence in Semarang has spatial and temporal variations. In general, subsidence rates in Semarang have an average rate of about 6 to 7 cm/year, with maximum rates that can go up to 14-19 cm/year at certain locations. The impact of land subsidence in Semarang can be seen in several forms, such as the wider expansion of (coastal) flooding areas "rob", cracking of buildings and infrastructure, and increased inland sea water intrusion. It also badly influences the quality and amenity of the living environment and life (e.g. health and sanitation condition) in the affected areas. In the case of Semarang, adaptation and mitigation are considered very important. We have been done some investigations to this area by field observations (mapping the flooded area, mapping the infrastructure problems, interviewing people and seeing the adaptations, conduct GPS measurement to see deformation, etc.), gather information from Government, from digital media, etc., and we noticed people increased their house, and the local goverment elevated the road and the bridge, etc. regulary over less decade periode as part of adaptation. We also noticed the Central Goverment built the dyke and pumping station. Our conclusions said that the adaptation only made temporaly since significant land subsidence keep coming and worsening by the sea level which is keep rising. Another conclusion, so far we have seen lack of mitigation program, monitoring or even inevective mitigation in Semarang related to this subsidence issue.

A SYSTEMATIC SEARCH FOR THE SPECTRA WITH FEATURES OF CRYSTALLINE SILICATES IN THE SPITZER IRS ENHANCED PRODUCTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Rui; Luo, Ali; Liu, Jiaming

2016-06-01

The crystalline silicate features are mainly reflected in infrared bands. The Spitzer Infrared Spectrograph (IRS) collected numerous spectra of various objects and provided a big database to investigate crystalline silicates in a wide range of astronomical environments. We apply the manifold ranking algorithm to perform a systematic search for the spectra with crystalline silicate features in the Spitzer IRS Enhanced Products available. In total, 868 spectra of 790 sources are found to show the features of crystalline silicates. These objects are cross-matched with the SIMBAD database as well as with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST)/DR2. Themore » average spectrum of young stellar objects shows a variety of features dominated either by forsterite or enstatite or neither, while the average spectrum of evolved objects consistently present dominant features of forsterite in AGB, OH/IR, post-AGB, and planetary nebulae. They are identified optically as early-type stars, evolved stars, galaxies and so on. In addition, the strength of spectral features in typical silicate complexes is calculated. The results are available through CDS for the astronomical community to further study crystalline silicates.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauer, Stephen J.

The elevation change data measured at the Bryan Mound Strategic Petroleum Reserve (SPR) site over the last 16+ years has been studied and a model utilized to project elevation changes into the future. The subsidence rate at Bryan Mound is low in comparison with other Strategic Petroleum Reserve sites and has decreased with time due to the maintenance of higher operating pressures and the normal decrease in creep closure rate of caverns with time. However, the subsidence at the site is projected to continue. A model was developed to project subsidence values 20 years into the future; no subsidence relatedmore » issues are apparent from these projections.« less

Communicating the AMFm message: exploring the effect of communication and training interventions on private for-profit provider awareness and knowledge related to a multi-country anti-malarial subsidy intervention

PubMed Central

2014-01-01

Background The Affordable Medicines Facility - malaria (AMFm), implemented at national scale in eight African countries or territories, subsidized quality-assured artemisinin combination therapy (ACT) and included communication campaigns to support implementation and promote appropriate anti-malarial use. This paper reports private for-profit provider awareness of key features of the AMFm programme, and changes in provider knowledge of appropriate malaria treatment. Methods This study had a non-experimental design based on nationally representative surveys of outlets stocking anti-malarials before (2009/10) and after (2011) the AMFm roll-out. Results Based on data from over 19,500 outlets, results show that in four of eight settings, where communication campaigns were implemented for 5–9 months, 76%-94% awareness of the AMFm ‘green leaf’ logo, 57%-74% awareness of the ACT subsidy programme, and 52%-80% awareness of the correct recommended retail price (RRP) of subsidized ACT were recorded. However, in the remaining four settings where communication campaigns were implemented for three months or less, levels were substantially lower. In six of eight settings, increases of at least 10 percentage points in private for-profit providers’ knowledge of the correct first-line treatment for uncomplicated malaria were seen; and in three of these the levels of knowledge achieved at endline were over 80%. Conclusions The results support the interpretation that, in addition to the availability of subsidized ACT, the intensity of communication campaigns may have contributed to the reported levels of AMFm-related awareness and knowledge among private for-profit providers. Future subsidy programmes for anti-malarials or other treatments should similarly include communication activities. PMID:24495691

The proximal part of the giant submarine Wailau landslide, Molokai, Hawaii

USGS Publications Warehouse

Clague, D.A.; Moore, J.G.

2002-01-01

The main break-in-slope on the northern submarine flank of Molokai at -1500 to -1250 m is a shoreline feature that has been only modestly modified by the Wailau landslide. Submarine canyons above the break-in-slope, including one meandering stream, were subaerially carved. Where such canyons cross the break-in-slope, plunge pools may form by erosion from bedload sediment carried down the canyons. West Molokai Volcano continued infrequent volcanic activity that formed a series of small coastal sea cliffs, now submerged, as the island subsided. Lavas exposed at the break-in-slope are subaerially erupted and emplaced tholeiitic shield lavas. Submarine rejuvenated-stage volcanic cones formed after the landslide took place and following at least 400-500 m of subsidence after the main break-in-slope had formed. The sea cliff on east Molokai is not the headwall of the landslide, nor did it form entirely by erosion. It may mark the location of a listric fault similar to the Hilina faults on present-day Kilauea Volcano. The Wailau landslide occurred about 1.5 Ma and the Kalaupapa Peninsula most likely formed 330??5 ka. Molokai is presently stable relative to sea level and has subsided no more than 30 m in the last 330 ka. At their peak, West and East Molokai stood 1.6 and 3 km above sea level. High rainfall causes high surface runoff and formation of canyons, and increases groundwater pressure that during dike intrusions may lead to flank failure. Active shield or postshield volcanism (with dikes injected along rift zones) and high rainfall appear to be two components needed to trigger the deep-seated giant Hawaiian landslides. ?? 2002 Elsevier Science B.V. All rights reserved.

The use of karst geomorphology for planning, hazard avoidance and development in Great Britain

NASA Astrophysics Data System (ADS)

Cooper, Anthony H.; Farrant, Andrew R.; Price, Simon J.

2011-11-01

Within Great Britain five main types of karstic rocks - dolomite, limestone, chalk, gypsum and salt - are present. Each presents a different type and severity of karstic geohazard which are related to the rock solubility and geological setting. Typical karstic features associated with these rocks have been databased by the British Geological Survey (BGS) with records of sinkholes, cave entrances, stream sinks, resurgences and building damage; data for more than half of the country has been gathered. BGS has manipulated digital map data, for bedrock and superficial deposits, with digital elevation slope models, superficial deposit thickness models, the karst data and expertly interpreted areas, to generate a derived dataset assessing the likelihood of subsidence due to karst collapse. This dataset is informed and verified by the karst database and marketed as part of the BGS GeoSure suite. It is currently used by environmental regulators, the insurance and construction industries, and the BGS semi-automated enquiry system. The database and derived datasets can be further combined and manipulated using GIS to provide other datasets that deal with specific problems. Sustainable drainage systems, some of which use soak-aways into the ground, are being encouraged in Great Britain, but in karst areas they can cause ground stability problems. Similarly, open loop ground source heat or cooling pump systems may induce subsidence if installed in certain types of karstic environments such as in chalk with overlying sand deposits. Groundwater abstraction also has the potential to trigger subsidence in karst areas. GIS manipulation of the karst information is allowing Great Britain to be zoned into areas suitable, or unsuitable, for such uses; it has the potential to become part of a suite of planning management tools for local and National Government to assess the long term sustainable use of the ground.

An earthquake history derived from stratigraphic and microfossil evidence of relative sea-level change at Coos Bay, southern coastal Oregon

USGS Publications Warehouse

Nelson, A.R.; Jennings, A.E.; Kashima, K.

1996-01-01

Much of the uncertainty in determining the number and magnitude of past great earthquakes in the Cascadia subduction zone of western North America stems from difficulties in using estuarine stratigraphy to infer the size and rate of late Holocene relative sea-level changes. A sequence of interbedded peaty and muddy intertidal sediment beneath a small, protected tidal marsh in a narrow inlet of Coos Bay, Oregon, records ten rapid to instantaneous rises in relative sea level. Each rise is marked by a contact that records an upward transition from peaty to muddy sediment. But only two contacts, dating from about 1700 and 2300 yr ago, show the site-wide extent and abrupt changes in lithology and foraminiferal and diatom assemblages that can be used to infer at least half a meter of sudden coseismic subsidence. Although the characteristics of a third, gradual contact do not differ from those of some contacts produced by nonseismic processes, regional correlation with other similar sequences and high-precision 14C dating suggest that the third contact records a great plate-boundary earthquake about 300 yr ago. A fourth contact formed too slowly to have been caused by coseismic subsidence. Because lithologic and microfossil data are not sufficient to distinguish a coseismic from a nonseismic origin for the other six peatmud contacts, we cannot determine earthquake recurrence intervals at this site. Similar uncertainties in great earthquake recurrence and magnitude prevail at similar sites elsewhere in the Cascadia subduction zone, except those with sequences showing changes in fossils indicative of > 1 m of sudden subsidence, sand sheets deposited by tsunamis, or liquefaction features.

A Novel Approach to Model Earth Fissure Caused by Extensive Aquifer Exploitation and its Application to the Wuxi Case, China

NASA Astrophysics Data System (ADS)

Ye, Shujun; Franceschini, Andrea; Zhang, Yan; Janna, Carlo; Gong, Xulong; Yu, Jun; Teatini, Pietro

2018-03-01

Initially observed in the semiarid basins of southwestern USA, earth fissures due to aquifer over-exploitation are presently threatening a large number of subsiding basins in various countries worldwide. Different mechanics have been proposed to explain this process, such as differential compaction, horizontal movements, and fault reactivation. Numerical modeling and prediction of this major geohazard caused by overuse of groundwater resources are challenging because of two main requirements: shifting from the classical continuous to discontinuous geomechanics and incorporating two-dimensional features (the earth fissures) into large three-dimensional (3-D) modeling domain (the subsiding basin). In this work, we proposed a novel modeling approach to simulate earth fissure generation and propagation in 3-D complex geological settings. A nested two-scale approach associated with an original nonlinear elastoplastic finite element/interface element simulator allows modeling the mechanics of earth discontinuities, in terms of both sliding and opening. The model is applied on a case study in Wuxi, China, where groundwater pumping between 1985 and 2004 has caused land subsidence larger than 2 m. The model outcomes highlight that the presence of a shallow (˜80 m deep) bedrock ridge crossing the Yangtze River delta is the key factor triggering the earth fissure development in this area. Bending of the alluvial deposits around the ridge tip and shear stress due to the uneven piezometric change and asymmetrical shape of the bedrock have caused the earth fissure to onset at the land surface and propagate downward to a maximum depth of about 20-30 m. Maximum sliding and opening are computed in the range of 10-40 cm, in agreement with the order of magnitude estimated in the field.

TerraSAR-X time-series interferometry detects human-induce subsidence in the Historical Centre of Hanoi, Vietnam

NASA Astrophysics Data System (ADS)

Le, Tuan; Chang, Chung-Pai; Nguyen, Xuan

2016-04-01

Hanoi was the capital of 12 Vietnamese dynasties, where the most historical relics, archaeological ruins and ancient monuments are located over Vietnam. However, those heritage assets are threatened by the land subsidence process occurred in recent decades, which mainly triggered by massive groundwater exploitation and construction activities. In this work, we use a set of high resolution TerraSAR-X images to map small-scale land subsidence patterns in the Historical Centre of Hanoi from April 2012 to November 2013. Images oversampling is integrated into the Small Baseline InSAR processing chain in order to enlarge the monitoring coverage by increasing the point-wise measurements, maintaining the monitoring scale of single building and monument. We analyzed over 2.4 million radar targets on 13.9 km2 area of interest based on 2 main sites: The Citadel, the Old Quarter and French Quarter. The highest subsidence rate recorded is -14.2 mm/year. Most of the heritage assets are considered as stable except the Roman Catholic Archdiocese and the Ceramic Mosaic Mural with the subsidence rates are -14.2 and -13.7 mm/year, respectively. Eventually, optical image and soil properties map are used to determine the causes of subsidence patterns. The result shows the strong relationships between the existing construction sites, the component of sediments and land subsidence processes that occurred in the study site.

Detecting and Measuring Land Subsidence in Houston-Galveston, Texas using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System Data, 2012-2016

NASA Astrophysics Data System (ADS)

Reed, A.; Baker, S.

2016-12-01

Several cities in the Houston-Galveston (HG) region in Texas have subsided up to 13 feet over several decades due to natural and anthropogenic processes [Yu et al. 2014]. Land subsidence, a gradual sinking of the Earth's surface, is an often human-induced hazard and a major environmental problem expedited by activities such as mining, oil and gas extraction, urbanization and excessive groundwater pumping. We are able to detect and measure subsidence in HG using interferometric synthetic aperture radar (InSAR) and global positioning systems (GPS). Qu et al. [2015] used ERS, Envisat, and ALOS-1 to characterize subsidence in HG from 1995 to 2011, but a five-year gap in InSAR measurements exists due to a lack of freely available SAR data. We build upon the previous study by comparing subsidence patterns detected by Sentinel-1 data starting in July 2015. We used GMT5SAR to generate a stack of interferograms with perpendicular baselines less than 100 meters and temporal baselines less than 100 days to minimize temporal and spatial decorrelation. We applied the short baseline subset (SBAS) time series processing using GIAnT and compared our results with GPS measurements. The implications of this work will strengthen land subsidence monitoring systems in HG and broadly aid in the development of effective water resource management policies and strategies.

An Analysis Model for Water Cone Subsidence in Bottom Water Drive Reservoirs

NASA Astrophysics Data System (ADS)

Wang, Jianjun; Xu, Hui; Wu, Shucheng; Yang, Chao; Kong, lingxiao; Zeng, Baoquan; Xu, Haixia; Qu, Tailai

2017-12-01

Water coning in bottom water drive reservoirs, which will result in earlier water breakthrough, rapid increase in water cut and low recovery level, has drawn tremendous attention in petroleum engineering field. As one simple and effective method to inhibit bottom water coning, shut-in coning control is usually preferred in oilfield to control the water cone and furthermore to enhance economic performance. However, most of the water coning researchers just have been done on investigation of the coning behavior as it grows up, the reported studies for water cone subsidence are very scarce. The goal of this work is to present an analytical model for water cone subsidence to analyze the subsidence of water cone when the well shut in. Based on Dupuit critical oil production rate formula, an analytical model is developed to estimate the initial water cone shape at the point of critical drawdown. Then, with the initial water cone shape equation, we propose an analysis model for water cone subsidence in bottom water reservoir reservoirs. Model analysis and several sensitivity studies are conducted. This work presents accurate and fast analytical model to perform the water cone subsidence in bottom water drive reservoirs. To consider the recent interests in development of bottom drive reservoirs, our approach provides a promising technique for better understanding the subsidence of water cone.

Use of Subsidized Child Care by Philadelphia Families: Findings and Discussion.

ERIC Educational Resources Information Center

Sterman, Sara Vernon; Dichter, Harriet

The study examined the consequences of delay in enrollment in subsidized child care and the impact of funding on the choices and perceived opportunities of families once they begin receiving child care subsidies. Subjects were 106 working families in Philadelphia who are either using subsidized child care or who are waiting to enroll in the…

75 FR 52753 - Agency Recordkeeping/Reporting Requirements Under Emergency Review by the Office of Management...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-27

...: TANF Emergency Fund Subsidized Employment Report, Form OFA- 200. OMB No.: New Collection. Description... implementing subsidized employment programs as a result of the availability of this new funding, and there is... interest in the number of individuals that are being placed in subsidized employment as a result of the...

The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States

USGS Publications Warehouse

Kuniansky, Eve L.; Weary, David J.; Kaufmann, James E.

2016-01-01

Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was $125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than $300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public.

Structural failure and drowning of Johnston Atoll, central Pacific Basin

NASA Astrophysics Data System (ADS)

Keating, Barbara H.

Emery (1956) and Ashmore (1973) described the geology of Johnston Atoll (Northern Line Islands chain) and pointed out the anomalous structure of the atoll. These studies led Ashmore )1973) to suggest that the atoll itself is tilted. Johnston Atoll appears to be an example of a seamount that is undergoing a transition from an atoll to a drowned seamount (guyot). Submersible studies of the shallow carbonate bank demonstrate that the carbonate bank displays important karstic features. Recent side-scan sonar studies of the southern flank of this seamount provide evidence that the southern flank of the seamount has undergone substantial mass-wasting. We hypothesize that the mass-wasting of the seamount has loaded the seafloor surrounding Johnston Island unevenly. The southeast Johnston Basin lies 700 m shallower than the southwest Johnston Basin. The loading of the southeast Johnston Basin has resulted in differential subsidence of the sea floor surrounding the seamount which has resulted in the tilting of the seamount (0.016°) and is responsible for the drowning of much of the reef. It is suggested that local structural failure, preferential erosion and drainage, and differential subsidence of seamounts can cause drowning of reefs which may lead to the formation of guyots.

Volcanic rocks cored on hess rise, Western Pacific Ocean

USGS Publications Warehouse

Vallier, T.L.; Windom, K.E.; Seifert, K.E.; Thiede, Jorn

1980-01-01

Large aseismic rises and plateaus in the western Pacific include the Ontong-Java Plateau, Magellan Rise, Shatsky Rise, Mid-Pacific Mountains, and Hess Rise. These are relatively old features that rise above surrounding sea floors as bathymetric highs. Thick sequences of carbonate sediments overlie, what are believed to be, Upper Jurassic and Lower Cretaceous volcanic pedestals. We discuss here petrological and tectonic implications of data from volcanic rocks cored on Hess Rise. The data suggest that Hess Rise originated at a spreading centre in the late early Cretaceous (Aptian-Albian stages). Subsequent off-ridge volcanism in the late Albian-early Cenomanian stages built a large archipelago of oceanic islands and seamounts composed, at least in part, of alkalic rocks. The volcanic platform subsided during its northward passage through the mid-Cretaceousequatorial zone. Faulting and uplift, and possibly volcanism, occurred in the latest Cretaceous (Campanian-Maastrichtian stages). Since then, Hess Rise continued its northward movement and subsidence. Volcanic rocks from holes drilled on Hess Rise during IPOD Leg 62 (Fig. 1) are briefly described here and we relate the petrological data to the origin and evolution of that rise. These are the first volcanic rocks reported from Hess Rise. ?? 1980 Nature Publishing Group.

The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States

NASA Astrophysics Data System (ADS)

Kuniansky, Eve L.; Weary, David J.; Kaufmann, James E.

2016-05-01

Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was 125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than 300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public.

The South Scandinavian crust: Structural complexities from seismic reflection and refraction profiling

NASA Astrophysics Data System (ADS)

Kinck, J. J.; Husebye, E. S.; Lund, C.-E.

1991-04-01

Pioneering work on mapping the Scandinavian crust commenced in the early 1960s and since then numerous profiling surveys have been undertaken, particularly as part of the on-going EUGENO-S project. However, the most significant contribution to mapping crustal structural details came from the M.V. Mobil Search cruises in the Skagerrak and off the West coast of Norway (16 s TWT reflection profiling). All past and present crustal profiling results have been integrated to produce detailed maps of Moho depths and crustal thicknesses for South Scandinavia. The thinnest crust is found in the North Sea and Skagerrak (approximately 20 km), while East-central Sweden features very thick crust (approximately 50 km). Other interesting features are the apparent correlation between crustal thinning and sedimentation/subsidence, magmatic activity, earthquake occurrences and the tectonic age of the crust. Moho depths and the crustal thicknesses clearly reflect the tectonic evolution and the present structural features of the region investigated.

Unstable ground in western North Dakota

USGS Publications Warehouse

Trimble, Donald E.

1979-01-01

Unstable ground in western North Dakota is mainly the result of mass-wasting processes. The units most affected are mudstones, siltstones, and sandstones of the Fort Union Formation. Ground instability generally is indicated by landslides, soil slides, or subsidence. Landslides are mostly of the slump-earthflow type and are localized along the flanks of the high buttes in southwestern North Dakota, including HT (Black) Butte, Chalky Buttes, Sentinel Butte, and East and West Rainy Buttes, and along parts of the valleys of the Des Lacs, Missouri, Little Missouri, and Heart Rivers. Landslides are sparse elsewhere. Soil slides are common in the areas south and southwest of the maximum position of the Pleistocene glacial ice margin on slopes of 15 degrees or more, and have taken place on some slopes as gentle as five degrees. The weathered, exposed surface of the Fort Union Formation seems to be especially susceptible to soil slides. Soil slides constitute the major type of ground instability in southwestern North Dakota. Subsidence is of two types: (1) subsidence over old underground mine workings, and (2) subsidence over naturally ignited and burned underground coal beds. Major subsidence has taken place over old, underground workings near Beulah, Wilton, Lehigh, Haynes, and Belfield, and lesser subsidence near Scranton, and west and north of Bowman. Thickness of overburden above the coal in all these areas is believed to be less than 30 m (100 ft). Subsidence has not taken place over old underground workings along the Des Lacs and-Souris valleys northwest of Minot, where the thickness of overburden is more than 60 m (200 ft). Spectacular subsidence has occurred over a burning underground coal bed at Burning Coal Vein Park near the Little Missouri River, northwest of Amidon.

Spatial prediction of ground subsidence susceptibility using an artificial neural network.

PubMed

Lee, Saro; Park, Inhye; Choi, Jong-Kuk

2012-02-01

Ground subsidence in abandoned underground coal mine areas can result in loss of life and property. We analyzed ground subsidence susceptibility (GSS) around abandoned coal mines in Jeong-am, Gangwon-do, South Korea, using artificial neural network (ANN) and geographic information system approaches. Spatial data of subsidence area, topography, and geology, as well as various ground-engineering data, were collected and used to create a raster database of relevant factors for a GSS map. Eight major factors causing ground subsidence were extracted from the existing ground subsidence area: slope, depth of coal mine, distance from pit, groundwater depth, rock-mass rating, distance from fault, geology, and land use. Areas of ground subsidence were randomly divided into a training set to analyze GSS using the ANN and a test set to validate the predicted GSS map. Weights of each factor's relative importance were determined by the back-propagation training algorithms and applied to the input factor. The GSS was then calculated using the weights, and GSS maps were created. The process was repeated ten times to check the stability of analysis model using a different training data set. The map was validated using area-under-the-curve analysis with the ground subsidence areas that had not been used to train the model. The validation showed prediction accuracies between 94.84 and 95.98%, representing overall satisfactory agreement. Among the input factors, "distance from fault" had the highest average weight (i.e., 1.5477), indicating that this factor was most important. The generated maps can be used to estimate hazards to people, property, and existing infrastructure, such as the transportation network, and as part of land-use and infrastructure planning.

Elimination of Subsidence with 26-mm-Wide Cages in Extreme Lateral Interbody Fusion.

PubMed

Lang, Gernot; Navarro-Ramirez, Rodrigo; Gandevia, Lena; Hussain, Ibrahim; Nakhla, Jonathan; Zubkov, Micaella; Härtl, Roger

2017-08-01

Extreme lateral interbody fusion (ELIF) has gained popularity as a minimally invasive technique for indirect decompression. However, graft subsidence potentially threatens long-term success of ELIF. This study evaluated whether 26-mm-wide cages can eliminate subsidence and subsequent loss of decompression in ELIF. Patients undergoing ELIF surgery using a 26-mm-wide cage were analyzed retrospectively. Patient demographics and perioperative data for radiographic and clinical outcomes were recorded. Radiographic parameters included regional sagittal lumbar lordosis and foraminal and disc height. Clinical parameters were evaluated using the Oswestry Disability Index and visual analog scale. Subsidence of 26-mm-wide cages was compared with previous outcomes of patients undergoing ELIF using 18-mm-wide and 22-mm-wide cages. There were 21 patients and 28 spinal segments analyzed. Radiographic outcome measures such as disc and foraminal height revealed significant improvement at follow-up compared with before surgery (P = 0.001). Postoperative to last follow-up cage subsidence translated into 0.34 mm ± 0.26 and -0.55 mm ± 0.64 in disc and foraminal height loss, respectively. Patients with 26-mm-wide cages experienced less subsidence by means of disc (26 mm vs. 18 mm and 22 mm, P ≤ 0.05) and foraminal height (26 mm vs. 18 mm, P = 0.005; 26 mm vs. 22 mm, P = 0.208) loss compared with patients receiving 18-mm-wide and 22-mm-wide cages. The 26-mm-wide cages almost eliminated cage subsidence in ELIF. Compared with 18-mm-wide and 22-mm-wide cages, 26-mm-wide cages significantly reduced cage subsidence in ELIF at midterm follow-up. A 26-mm-wide cage should be used in ELIF to achieve sustained indirect decompression. Copyright © 2017. Published by Elsevier Inc.

Land subsidence in the San Joaquin Valley, California, USA, 2007-14

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin

2015-01-01

Rapid land subsidence was recently measured using multiple methods in two areas of the San Joaquin Valley (SJV): between Merced and Fresno (El Nido), and between Fresno and Bakersfield (Pixley). Recent land-use changes and diminished surface-water availability have led to increased groundwater pumping, groundwater-level declines, and land subsidence. Differential land subsidence has reduced the flow capacity of water-conveyance systems in these areas, exacerbating flood hazards and affecting the delivery of irrigation water. Vertical land-surface changes during 2007–2014 were determined by using Interferometric Synthetic Aperture Radar (InSAR), Continuous Global Positioning System (CGPS), and extensometer data. Results of the InSAR analysis indicate that about 7600 km2 subsided 50–540 mm during 2008–2010; CGPS and extensometer data indicate that these rates continued or accelerated through December 2014. The maximum InSAR-measured rate of 270 mm yr−1 occurred in the El Nido area, and is among the largest rates ever measured in the SJV. In the Pixley area, the maximum InSAR-measured rate during 2008–2010 was 90 mm yr−1. Groundwater was an important part of the water supply in both areas, and pumping increased when land use changed or when surface water was less available. This increased pumping caused groundwater-level declines to near or below historical lows during the drought periods 2007–2009 and 2012–present. Long-term groundwater-level and land-subsidence monitoring in the SJV is critical for understanding the interconnection of land use, groundwater levels, and subsidence, and evaluating management strategies that help mitigate subsidence hazards to infrastructure while optimizing water supplies.

On correlation between urban development, land subsidence and flooding phenomena in Jakarta

NASA Astrophysics Data System (ADS)

Abidin, H. Z.; Andreas, H.; Gumilar, I.; Wibowo, I. R. R.

2015-06-01

Jakarta is the capital city of Indonesia with a population of about 10.2 million people, inhabiting an area of about 660 square-km. It is located within a deltaic plain and passes by 13 natural and artificial rivers. In the last three decades, urban development of Jakarta has grown very rapidly in the sectors of industry, trade, transportation, real estate and many others, which has caused several negative environmental impacts. In turns Jakarta is then prone toward a few natural hazards mainly land subsidence and flooding. In general, based on geodetic measurement methods (e.g. Leveling, GPS surveys, and InSAR), conducted since 1982 up to 2014, it is obtained that land subsidence in Jakarta exhibits spatial and temporal variations, with the typical rates of about 3 to 10 cm year-1. In general, the impacts of land subsidence in Jakarta can be seen in the forms of cracking of permanent constructions and roads, changes in river canal and drain flow systems, wider expansion of coastal and/or inland flooding areas, and malfunction of drainage system. Several areas along the coast of Jakarta already have experienced tidal flooding during high tide periods. These coastal flooding usually occurs in the areas with relatively large subsidence rates. Subsidence in the areas along the rivers which are flowing throughout Jakarta will also worsen the impacts of riverine flooding. The changes in river canal and drain flow systems and malfunction of drainage system due to land subsidence will also aggravate the flooding. Land subsidence will have direct and indirect affects with the flooding in Jakarta, both in coastal or inland areas.

Combination of poroelasticity theory and constant strain rate test in modelling land subsidence due to groundwater extraction

NASA Astrophysics Data System (ADS)

Pham, Tien Hung; Rühaak, Wolfram; Sass, Ingo

2017-04-01

Extensive groundwater extraction leads to a drawdown of the ground water table. Consequently, soil effective stress increases and can cause land subsidence. Analysis of land subsidence generally requires a numerical model based on poroelasticity theory, which was first proposed by Biot (1941). In the review of regional land subsidence accompanying groundwater extraction, Galloway and Burbey (2011) stated that more research and application is needed in coupling of stress-dependent land subsidence process. In geotechnical field, the constant rate of strain tests (CRS) was first introduced in 1969 (Smith and Wahls 1969) and was standardized in 1982 through the designation D4186-82 by American Society for Testing and Materials. From the reading values of CRS tests, the stress-dependent parameters of poroelasticity model can be calculated. So far, there is no research to link poroelasticity theory with CRS tests in modelling land subsidence due to groundwater extraction. One dimensional CRS tests using conventional compression cell and three dimension CRS tests using Rowe cell were performed. The tests were also modelled by using finite element method with mixed elements. Back analysis technique is used to find the suitable values of hydraulic conductivity and bulk modulus that depend on the stress or void ratio. Finally, the obtained results are used in land subsidence models. Biot, M. A. (1941). "General theory of three-dimensional consolidation." Journal of applied physics 12(2): 155-164. Galloway, D. L. and T. J. Burbey (2011). "Review: Regional land subsidence accompanying groundwater extraction." Hydrogeology Journal 19(8): 1459-1486. Smith, R. E. and H. E. Wahls (1969). "Consolidation under constant rates of strain." Journal of Soil Mechanics & Foundations Div.

Regional management of farmland feeding geese using an ecological prioritization tool.

PubMed

Madsen, Jesper; Bjerrum, Morten; Tombre, Ingunn M

2014-10-01

Wild geese foraging on farmland cause increasing conflicts with agricultural interests, calling for a strategic approach to mitigation. In central Norway, conflicts between farmers and spring-staging pink-footed geese feeding on pastures have escalated. To alleviate the conflict, a scheme by which farmers are subsidized to allow geese to forage undisturbed was introduced. To guide allocation of subsidies, an ecological-based ranking of fields at a regional level was recommended and applied. Here we evaluate the scheme. On average, 40 % of subsidized fields were in the top 5 % of the ranking, and 80 % were within the top 20 %. Goose grazing pressure on subsidized pastures was 13 times higher compared to a stratified random selection of non-subsidized pastures, capturing 67 % of the pasture feeding geese despite that subsidized fields only comprised 13 % of the grassland area. Close dialogue between scientists and managers is regarded as a key to the success of the scheme.

Implications of ground-deformation measurements across earth fissures in subsidence areas in the southwestern USA

USGS Publications Warehouse

Holzer, Thomas L.

2010-01-01

Ground deformation was monitored at earth fissures in areas of land subsidence induced by groundwater extraction in the southwestern United States. The ground deformation is consistent with the mechanism that fissures are caused by horizontal strains generated by bending of overburden in response to localized differential compaction. Subsidence profiles indicated that localized differential subsidence occurred across the fissures and that maximum convex-upward curvature was at the fissure. The overall shape of the profile stayed similar with time, and maximum curvature remained stationary at the fissure. Horizontal displacements were largest near the fissure, and generally were small to negligible away from the fissure. Maximum tensile horizontal strains were at the fissure and coincided with maximum curvature in the subsidence profiles. Horizontal tensile strain continued to accumulate at fissures after they formed with rates of opening ranging from 30 to 120 microstrain/year at fissures in Arizona.

Analysis of Mining-Induced Subsidence Prediction by Exponent Knothe Model Combined with Insar and Leveling

NASA Astrophysics Data System (ADS)

Chen, Lei; Zhang, Liguo; Tang, Yixian; Zhang, Hong

2018-04-01

The principle of exponent Knothe model was introduced in detail and the variation process of mining subsidence with time was analysed based on the formulas of subsidence, subsidence velocity and subsidence acceleration in the paper. Five scenes of radar images and six levelling measurements were collected to extract ground deformation characteristics in one coal mining area in this study. Then the unknown parameters of exponent Knothe model were estimated by combined levelling data with deformation information along the line of sight obtained by InSAR technique. By compared the fitting and prediction results obtained by InSAR and levelling with that obtained only by levelling, it was shown that the accuracy of fitting and prediction combined with InSAR and levelling was obviously better than the other that. Therefore, the InSAR measurements can significantly improve the fitting and prediction accuracy of exponent Knothe model.

Ground Subsidence Monitoring with MT-InSAR and Mechanism Inversion Over Xi'an, China

NASA Astrophysics Data System (ADS)

Peng, M. M.; Zhao, C. Y.; Zhang, Q.; Zhang, J.; Liu, Y. Y.

2018-04-01

The ancient Xi'an, China, has been suffering severe land subsidence and ground fissure hazards since the 1960s, which has affected the safety of Subways. Multi-sensor SAR data are conducted to monitor the latest complex ground deformation and its influence on subway line No.3 over Xi'an. Annual deformation rates have been retrieved to reveal the spatiotemporal evolution of ground subsidence in Xi'an city from 2013 to 2017. Meanwhile, the correlation between land subsidence and ground fissures are analyzed by retrieving the deformation differences in both sides of the fissures. Besides, the deformation along subway line No. 3 is analyzed, and the fast deformation section is quantitatively studied. Finally, a flat lying sill model with distributed contractions is implemented to model the InSAR deformation over YHZ subsidence center, which manifests that the ground deformation is mainly caused by groundwater withdrawal.

InSAR detects increase in surface subsidence caused by an Arctic tundra fire

USGS Publications Warehouse

Liu, Lin; Jafarov, Elchin E.; Schaefer, Kevin M.; Jones, Benjamin M.; Zebker, Howard A.; Williams, Christopher A.; Rogan, John; Zhang, Tingjun

2014-01-01

Wildfire is a major disturbance in the Arctic tundra and boreal forests, having a significant impact on soil hydrology, carbon cycling, and permafrost dynamics. This study explores the use of the microwave Interferometric Synthetic Aperture Radar (InSAR) technique to map and quantify ground surface subsidence caused by the Anaktuvuk River fire on the North Slope of Alaska. We detected an increase of up to 8 cm of thaw-season ground subsidence after the fire, which is due to a combination of thickened active layer and permafrost thaw subsidence. Our results illustrate the effectiveness and potential of using InSAR to quantify fire impacts on the Arctic tundra, especially in regions underlain by ice-rich permafrost. Our study also suggests that surface subsidence is a more comprehensive indicator of fire impacts on ice-rich permafrost terrain than changes in active layer thickness alone.

ANALYSIS OF CLINICAL AND DERMOSCOPIC FEATURES FOR BASAL CELL CARCINOMA NEURAL NETWORK CLASSIFICATION

PubMed Central

Cheng, Beibei; Stanley, R. Joe; Stoecker, William V; Stricklin, Sherea M.; Hinton, Kristen A.; Nguyen, Thanh K.; Rader, Ryan K.; Rabinovitz, Harold S.; Oliviero, Margaret; Moss, Randy H.

2012-01-01

Background Basal cell carcinoma (BCC) is the most commonly diagnosed cancer in the United States. In this research, we examine four different feature categories used for diagnostic decisions, including patient personal profile (patient age, gender, etc.), general exam (lesion size and location), common dermoscopic (blue-gray ovoids, leaf-structure dirt trails, etc.), and specific dermoscopic lesion (white/pink areas, semitranslucency, etc.). Specific dermoscopic features are more restricted versions of the common dermoscopic features. Methods Combinations of the four feature categories are analyzed over a data set of 700 lesions, with 350 BCCs and 350 benign lesions, for lesion discrimination using neural network-based techniques, including Evolving Artificial Neural Networks and Evolving Artificial Neural Network Ensembles. Results Experiment results based on ten-fold cross validation for training and testing the different neural network-based techniques yielded an area under the receiver operating characteristic curve as high as 0.981 when all features were combined. The common dermoscopic lesion features generally yielded higher discrimination results than other individual feature categories. Conclusions Experimental results show that combining clinical and image information provides enhanced lesion discrimination capability over either information source separately. This research highlights the potential of data fusion as a model for the diagnostic process. PMID:22724561

Latest Pannonian and Quaternary evolution at the transition between Eastern Alps and Pannonian Basin: new insights from geophysical, sedimentological and geochronological data

NASA Astrophysics Data System (ADS)

Zámolyi, A.; Salcher, B.; Draganits, E.; Exner, U.; Wagreich, M.; Gier, S.; Fiebig, M.; Lomax, J.; Surányi, G.; Diel, M.; Zámolyi, F.

2017-07-01

The transition zone between Eastern Alps and Pannonian Basin is a key area for the investigation of the interplay between regional uplift, local tectonic subsidence and depositional environment. Our study area, the western margin of the Little Hungarian Plain, is characterized by gentle hills, plateaus and depressions, of which several are filled by lakes—including one of Austria's largest and shallowest lakes, Lake Neusiedl. Geological investigation is hampered by the scarcity of outcrops, and thus direct observation of sedimentological or structural features is difficult. Despite a long research history in the area, a consistent landscape evolution model considering all relevant constraints is lacking so far. In this study, we apply multidisciplinary methods to decipher the complex tectonic and fluvial depositional evolution of the region. Local data from shallow-lake drilling and seismic investigation are combined with regional data from industrial seismics and core data to gain new insights into the latest Pannonian (Late Miocene) and Quaternary evolution. Shallow-lake seismic data show the erosionally truncated Pannonian sediments dipping and thickening toward southeast, toward the modern depocenter of the Little Hungarian Plain. Overlying Quaternary fluvial sediments show a very similar thickening trend except for the area on the plateau north of the lake indicating ongoing subsidence in major parts of the basin. Drill cores from locations along the lake seismic lines were analyzed concerning their age, mineralogy and heavy minerals and compared with outcrop samples from the surrounding plains and the plateau to derive indications on sediment provenance. A key observation is the apparent lack of a significant gravel layer on top of the tilted Pannonian sediments beneath Lake Neusiedl. Small-scale faults can be observed in the lake seismic sections along with key sedimentary features. Significant differences of the current elevation of the top Pannonian between the surrounding plains and the plateau indicate post-Pannonian normal faulting, which is a key process in shaping the present-day morphology of the region. Luminescence ages of samples from the Quaternary fluvial gravels on top of the Pannonian sediments are a significantly higher (>300 ka) compared to the gravels in the plain (102 ± 11 and 76 ± 8 ka), suggesting ongoing tectonic subsidence.

Tectonic influences on the preservation of marine terraces: Old and new evidence from Santa Catalina Island, California

USGS Publications Warehouse

Schumann, R. Randall; Minor, Scott A.; Muhs, Daniel R.; Groves, Lindsey T.; McGeehin, John P.

2012-01-01

The California Channel Islands contain some of the best geologic records of past climate and sea-level changes, recorded in uplifted, fossil-bearing marine terrace deposits. Among the eight California Channel Islands and the nearby Palos Verdes Hills, only Santa Catalina Island does not exhibit prominent emergent marine terraces, though the same terrace-forming processes that acted on the other Channel Islands must also have occurred on Santa Catalina. We re-evaluated previous researchers' field evidence and examined new topographic, bathymetric, and stream-profile data in order to find possible explanations for the lack of obvious marine terrace landforms or deposits on the island today. The most likely explanation is associated with the island's unresolved tectonic history, with evidence for both recent uplift and subsidence being offered by different researchers. Bathymetric and seismic reflection data indicate the presence of submerged terrace-like landforms from a few meters below present sea level to depths far exceeding that of the lowest glacial lowstand, suggesting that the Catalina Island block may have subsided, submerging marine terraces that would have formed in the late Quaternary. Similar submerged marine terrace landforms exist offshore of all of the other California Channel Islands, including some at anomalously great depths, but late Quaternary uplift is well documented on those islands. Therefore, such submarine features must be more thoroughly investigated and adequately explained before they can be accepted as definitive evidence of subsidence. Nevertheless, the striking similarity of the terrace-like features around Santa Catalina Island to those surrounding the other, uplifting, Channel Islands prompted us to investigate other lines of evidence of tectonic activity, such as stream profile data. Recent uplift is suggested by disequilibrium stream profiles on the western side of the island, including nickpoints and profile convexities. Rapid uplift is also indicated by the island's highly dissected, steep topography and abundant landslides. A likely cause of uplift is a restraining bend in the offshore Catalina strike-slip fault. Our analysis suggests that Santa Catalina Island has recently experienced, and may still be experiencing, relatively rapid uplift, causing intense landscape rejuvenation that removed nearly all traces of marine terraces by erosion. A similar research approach, incorporating submarine as well as subaerial geomorphic data, could be applied to many tectonically active coastlines in which a marine terrace record appears to be missing.

Reproductive Physiology of Marsupials

ERIC Educational Resources Information Center

Sharman, G. B.

1970-01-01

Describes some unique features of marsupial reproduction which include (1) chromosomal sex determination, (2) reproductive system, (3) birth, (4) location, and (5) embryonic diapause. These features suggest that viviparity evolved separately in eutherian and marsupial stocks after their derivation from a common oviparous ancestor. Bibliography.…

Effect of sex, age, and breed on genetic recombination features in cattle

USDA-ARS?s Scientific Manuscript database

Meiotic recombination is a fundamental biological process which generates genetic diversity, affects fertility, and influences evolvability. Here we investigate the roles of sex, age, and breed in cattle recombination features, including recombination rate, location and crossover interference. Usin...

Determinants of interest rates on tax-exempt hospital bonds.

PubMed

Grossman, M; Goldman, F; Nesbitt, S W; Mobilia, P

1993-12-01

The aim of this paper is to examine the determinants of interest rates on tax-exempt hospital bonds. The results highlight the potential and actual roles of Federal and state policy in the determination of these rates. The shift to a Prospective Payment System under Medicare has subsidized the borrowing costs of some hospitals at the expense of others. The selection of underwriters by negotiation rather than by competitive bidding results in higher interest rates. The Federal tax act of 1986 raised the cost of hospital debt by encouraging bond issues to contain call features.

Biological robustness.

PubMed

Kitano, Hiroaki

2004-11-01

Robustness is a ubiquitously observed property of biological systems. It is considered to be a fundamental feature of complex evolvable systems. It is attained by several underlying principles that are universal to both biological organisms and sophisticated engineering systems. Robustness facilitates evolvability and robust traits are often selected by evolution. Such a mutually beneficial process is made possible by specific architectural features observed in robust systems. But there are trade-offs between robustness, fragility, performance and resource demands, which explain system behaviour, including the patterns of failure. Insights into inherent properties of robust systems will provide us with a better understanding of complex diseases and a guiding principle for therapy design.

Modeling the Chinese language as an evolving network

NASA Astrophysics Data System (ADS)

Liang, Wei; Shi, Yuming; Huang, Qiuling

2014-01-01

The evolution of Chinese language has three main features: the total number of characters is gradually increasing, new words are generated in the existing characters, and some old words are no longer used in daily-life language. Based on the features, we propose an evolving language network model. Finally, we use this model to simulate the character co-occurrence networks (nodes are characters, and two characters are connected by an edge if they are adjacent to each other) constructed from essays in 11 different periods of China, and find that characters that appear with high frequency in old words are likely to be reused when new words are formed.

Land-surface subsidence in the Texas coastal region

USGS Publications Warehouse

Ratzlaff, Karl W.

1980-01-01

In southeastern Jackson County and northwestern Matagorda County, the land surface subsided more than 1.5 feet (0.46 meter) during 1943-73 as a result of ground-water withdrawals. Withdrawals of oil, gas, and associated ground water caused more than 5 feet (1.5 meters) of subsidence during 1942-75 in the western part of Corpus Christi in Nueces County.

Contribution of Sediment Compaction/Loading to the Ganges-Bangladesh Delta Subsidence

NASA Astrophysics Data System (ADS)

Karpytchev, Mikhail; Krien, Yann; Ballu, Valerie; Becker, Melanie; Calmant, Stephane; Spada, Giorgio; Guo, Junyi; Khan, Zahirul; Shum, Ck

2016-04-01

A pronounced spatial variability characterizes the subsidence/uplift rates in the Ganges-Bangladesh delta estimated from both sediment cores and modern geodetic techniques. The large variability of the subsidence rates suggests an interplay of different natural and anthropogenic processes including tectonics, sediment loading and sediment compaction, groundwater extaction among many others drivers of the delta vertical land movements.In this study, we focus on estimating the subsidence rates due to the sediments transported by the Ganges-Brahmaputra since the last 18 000 years. The delta subsidence induced by the sediment loading and the resulting sea level changes are modelled by the TABOO and SELEN software (Spada, 2003; Stocchi and Spada, 2007) in the framework of a gravitationally self-consistent Earth model. The loading history was obtained from available sediment cores and from the isopach map of Goodbread and Kuehl (2000). The results demonstrate that the delta loading enhanced by the Holocene sedimention can be responsable for a regular subsidence across the Ganges-Brahmaputra delta with an amplitude of 1-5 mm/yr along the Bengal coast. These estimates demonstrate that the contribution of the Holocene as well as modern sediment loading should be taken into account in climate change mitigation politicy for Bangladesh.

Origins of oblique-slip faulting during caldera subsidence

NASA Astrophysics Data System (ADS)

Holohan, Eoghan P.; Walter, Thomas R.; Schöpfer, Martin P. J.; Walsh, John J.; van Wyk de Vries, Benjamin; Troll, Valentin R.

2013-04-01

Although conventionally described as purely dip-slip, faults at caldera volcanoes may have a strike-slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural calderas. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (2) horizontal translation arising from off-centered or "asymmetric" subsidence. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during caldera subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.

Subsidence and well failure in the South Belridge Diatomite field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rouffignac, E.P. de; Bondor, P.L.; Karanikas, J.M. Hara, S.K.

1995-12-31

Withdrawal of fluids from shallow, thick and low strength rock can cause substantial reservoir compaction leading to surface subsidence and well failure. This is the case for the Diatomite reservoir, where over 10 ft of subsidence have occurred in some areas. Well failure rates have averaged over 3% per year, resulting in several million dollars per year in well replacement and repair costs in the South Belridge Diatomite alone. A program has been underway to address this issue, including experimental, modeling and field monitoring work. An updated elastoplastic rock law based on laboratory data has been generated which includes notmore » only standard shear failure mechanisms but also irreversible pore collapse occurring at low effective stresses (<150 psi). This law was incorporated into a commercial finite element geomechanics simulator. Since the late 1980s, a network of level survey monuments has been used to monitor subsidence at Belridge. Model predictions of subsidence in Section 33 compare very well with field measured data, which show that water injection reduces subsidence from 7--8 inches per year to 1--2 inches per year, but does not abate well failure.« less

InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

USGS Publications Warehouse

Rykhus, Russell P.; Lu, Zhong

2008-01-01

Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

An evaluation of processing InSAR Sentinel-1A/B data for correlation of mining subsidence with mining induced tremors in the Upper Silesian Coal Basin (Poland)

NASA Astrophysics Data System (ADS)

Krawczyk, Artur; Grzybek, Radosław

2018-01-01

The Satellite Radar Interferometry is one of the common methods that allow to measure the land subsidence caused by the underground black coal excavation. The interferometry images processed from the repeat-pass Synthetic Aperture Radar (SAR) systems give the spatial image of the terrain subjected to the surface subsidence over mining areas. Until now, the InSAR methods using data from the SAR Systems like ERS-1/ERS-2 and Envisat-1 were limited to a repeat-pass cycle of 35-day only. Recently, the ESA launched Sentinel-1A and 1B, and together they can provide the InSAR coverage in a 6-day repeat cycle. The studied area was the Upper Silesian Coal Basin in Poland, where the underground coal mining causes continuous subsidence of terrain surface and mining tremors (mine-induced seismicity). The main problem was with overlapping the subsidence caused by the mining exploitation with the epicentre tremors. Based on the Sentinel SAR images, research was done in regard to the correlation between the short term ground subsidence range border and the mine-induced seismicity epicentres localisation.

Preventing and controlling land subsidence in Shanghai -towards more integrated and effective land use and ground water governance in the Yangtze Delta

NASA Astrophysics Data System (ADS)

Dai, Liping

2016-04-01

The Yangtze Delta, covers 210,700 square kilometers and with 156 million inhabitants (NRDC, 2010; The National Bureau of Statistics, 2011), is one of the areas most severely affected by land subsidence in China. Up to 2012, the area with cumulative subsidence above 200 mm in Yangtze Delta has been closed to 10,000 square kilometers. Shanghai, located at the estuary of the Yangtze River and with a population of 23 million, is the most densely populated city in Yangtze Delta (The National Bureau of Statistics, 2011). Since 1921, the recorded cumulative subsidence has been 200 to 300 mm in the central area of the city (Chai, Shen, Zhu, & Zhang, 2005). Excessive pumping of groundwater is considered to be the leading reason, accounts for nearly 70%, of the city's land subsidence, the weight of skyscrapers and global warming also play hefty roles (30%) (Springer, 2012). Research has shown that the main method to control land subsidence in Shanghai is to prevent groundwater from dropping (Chai, Shen, Zhu, & Zhang, 2005), the city has made great efforts in this regard since 1965 (the beginning of the so-called "control period"), for example, it has been recharging underground water through 121 wells with more than 60,000 tons every day since 2012 (Chinadaily, 2012). It is a huge burden considering the city has been suffering from a shortage of fresh water. In 2013, with the other two provinces of Jiangsu and Zhejiang in Yangtze Delta, Shanghai signed a delta cooperation agreement on the prevention and control of land subsidence and jointly issued a Prevention and Control Planning on Land Subsidence in Yangtze Delta (2014-2020), which aims to establish a long-effect mechanism in the delta scope. This research aims to analyze and assess the land and groundwater governance arrangements related to land subsidence in the Yangtze Delta in general and Shanghai in specific, in order to develop optimizing adaptation strategies and associated governance arrangements. It examines the institutional arrangements of land subsidence prevention and control at three levels, i.e. the national level, the regional level (Yangtze Delta) and the city level (Shanghai). A three-step interdisciplinary diagnostic method, based on water system analysis, economics, law and public administration, will be applied.

Multiband PSInSAR and long-period monitoring of land subsidence in a strategic detrital aquifer (Vega de Granada, SE Spain): An approach to support management decisions

NASA Astrophysics Data System (ADS)

Mateos, Rosa María; Ezquerro, Pablo; Luque-Espinar, Juan Antonio; Béjar-Pizarro, Marta; Notti, Davide; Azañón, Jose Miguel; Montserrat, Oriol; Herrera, Gerardo; Fernández-Chacón, Francisca; Peinado, Tomás; Galve, Jorge Pedro; Pérez-Peña, Vicente; Fernández-Merodo, Jose A.; Jiménez, Jorge

2017-10-01

This work integrates detailed geological and hydrogeological information with PSI data to obtain a better understanding of subsidence processes detected in the detrital aquifer of the Vega de Granada (SE Spain) during the past 13 years. Ground motion was monitored by exploiting SAR images from the ENVISAT (2003-2009), Cosmo-SkyMed (2011-2014) and Sentinel-1A (2015-2016) satellites. PSInSAR results show an inelastic deformation in the aquifer and small land surface displacements (up to -55 mm). The most widespread land subsidence is detected during the ENVISAT period (2003-2009), which coincided with a long, dry period in the region. The highest displacement rates recorded during this period (up to 10 mm/yr) were detected in the central part of the aquifer, where many villages are located. For this period, there is a good correlation between groundwater level depletion and the augmentation of the average subsidence velocity and slight hydraulic head changes (<2 m) have a rapid ground motion response. The Cosmo-SkyMed period (2011-2014) coincided with a rainy period, and the land subsidence is only concentrated in some points. Rates of average subsidence up to 11.5 mm/yr are obtained for this period and are anthropogenic in origin, being related to earthmoving works. During the Sentinel-1A monitoring period (2015-2016) most of the region showed no deformation, except for some points of unknown origin in the NE sector. A general conclusion is that there is a clear lithological control in the spatial distribution of ground subsidence; all the subsiding areas detected are located where a higher clay content was identified. Although the SE sector of the aquifer had more intense groundwater exploitation, no land subsidence processes were detected, as coarse-grained sediments predominate in the substratum. This research will contribute to the drawing-up of a management plan for the sustainable use of this strategic aquifer, taking into account critical levels of groundwater depletion to avoid land subsidence in the areas identified as vulnerable. The European Space Agency satellite Sentinel-1A could be an effective decision-making tool in the near future.

New insights on the subsidence of the Ganges-Brahmaputra Delta Plain by using 2D multichannel seismic data, gravity and flexural modeling, BanglaPIRE Project

NASA Astrophysics Data System (ADS)

Grall, C.; Pickering, J.; Steckler, M. S.; Spiess, V.; Seeber, L.; Paola, C.; Goodbred, S. L., Jr.; Palamenghi, L.; Schwenk, T.

2015-12-01

Deltas can subside very fast, yet many deltas remain emergent over geologic time. A large sediment input is often enough to compensate for subsidence and rising sea level to keep many deltas at sea level. This implies a balance between subsidence and sedimentation, both of which may, however, be controlled by independent factors such as sediment supply, tectonic loads and sea-level change. We here examine the subsidence of the Ganges-Brahmaputra Delta (GBD). Located in the NE boundary of the Indian-Eurasian collision zone, the GBD is surrounded by active uplifts (Indo-Burma Fold Belt and the Shillong Massif). The pattern of subsidence from these tectonic loads can strongly vary depending on both loads and lithospheric flexural rigidity, both of which can vary in space and time. Sediment cover changes both the lithostatic pressure and the thermal properties and thus the rigidity of the lithosphere. While sediments are deposited cold, they also insulate the lithosphere, acting as a thermal blanket to increase lower crustal temperatures. These effects are a function of sedimentation rates and may be more important where the lithosphere is thin. At the massive GBD the impact of sedimentation should be considered for properly constraining flexural subsidence. The flexural rigidity of the lithosphere is here modeled by using a yield-stress envelope based on a thermomechanic model that includes geothermal changes associated with sedimentation. Models are constrained by using two different data sets, multichannel seismic data correlated to borehole stratigraphy, and gravity data. This approach allows us to determine the Holocene regional distribution of subsidence from the Hinge Zone to the Bengal Fan and the mass-anomalies associated with the flexural loading. Different end-member scenarios are explored for reproducing the observed land tilting and gravity anomalies. For all scenarios considered, data can be reproduced only if we consider an extremely weak lithosphere and we will quantify the extent that this weakness is influenced by the extreme sediment thickness of the delta. While the distribution of the present-day subsidence suggests that sediment compaction plays a major role on the current subsidence over the delta, its role over a geological time frame is probably minor.

On the role of mantle depletion and small-scale convection in post rift basin evolution (Invited)

NASA Astrophysics Data System (ADS)

Petersen, K.; Nielsen, S. B.

2013-12-01

Subsidence and heat flow evolution of the oceanic lithosphere appears to be consistent with the conductive cooling of a ~100 km plate overlying asthenospheric mantle of constant entropy. The physical mechanism behind plate-like subsidence has been suggested to be the result of small-scale convective instabilities which transport heat energy to the base of the lithosphere and cause an eventual departure from half space-like cooling by inhibiting subsidence of old ocean floor and causing an asymptotic surface heat flow of ~50 mW/m^2. Here, we conduct a number of numerical thermo-mechanical experiments of oceanic lithosphere cooling for different models of temperature- and pressure-dependent viscosity. We show that uniform (P, T-dependent) mantle viscosity cannot both explain half space-like subsidence for young (<70 Mr) lithosphere as well as a relatively high (>50 mW/m^2) surface heat flow which is observed above old (>100 Myr) lithosphere. The latter requires vigorous sub lithospheric convection which would lead to early (~1Myr) onset of convective instability at shallow depth (<60 km) and therefore insufficient initial subsidence. To resolve this paradox, we employ models which account for the density decrease and viscosity increase due to depletion during mid-ocean ridge melting. We demonstrate that the presence of a mantle restite layer within the lithosphere hinders convection at shallow depth and therefore promotes plate-like cooling. A systematic parameter search among 280 different numerical experiments indicates that models with 60-80 km depletion thickness minimize misfit with subsidence and heat flow data. This is consistent with existing petrological models of mid-ocean ridge melting. Our models further indicate that the post-rift subsidence pattern where little or no melting occurred during extension (e.g. non-volcanic margins and continental rifts) may differ from typical oceanic plate-like subsidence by occurring at a nearly constant rate rather than at an exponentially decaying rate. Model comparison with subsidence histories inferred from backstripping analysis implies that this is indeed often the case. Accordingly, existing thermal models of continental rifting which assume plate-like cooling (and is often calibrated from oceanic data) are likely to yield inaccurate predictions in terms of subsidence and heat flow evolution.

Cretaceous to Recent Asymetrical Subsidence of South American and West African Conjugate Margins

NASA Astrophysics Data System (ADS)

Kenning, J.; Mann, P.

2017-12-01

Two divergent interpretations have been proposed for South American rifted-passive margins: the "mirror hypothesis" proposes that the rifted margins form symmetrically from pure shear of the lithosphere while upper-plate-lower plate models propose that the rifted margins form asymmetrically by simple shear. Models based on seismic reflection and refraction imaging and comparison of conjugate, rifted margins generally invoke a hybrid stretching process involving elements of both end member processes along with the effects of mantle plumes active during the rift and passive margin phases. We use subsidence histories of 14, 1-7 km-deep exploration wells located on South American and West African conjugate pairs now separated by the South Atlantic Ocean, applying long-term subsidence to reveal the symmetry or asymmetry of the underlying, conjugate, rift processes. Conjugate pairs characterize the rifted margin over a distance of 3500 km and include: Colorado-South Orange, Punta Del Este-North Orange, South Pelotas-Lüderitz and the North Pelotas-Walvis Basins. Of the four conjugate pairs, more rapid subsidence on the South American plate is consistently observed with greater initial rift and syn-rift subsidence rates of >60m/Ma (compared to <15 m/Ma) between approximately 145-115 Ma. High rates of tectonically-induced subsidence >100 m/Ma are observed offshore South Africa between approximately 120-80 Ma, compatible with onset of the post-rift thermal sag phase. During this period the majority of burial is completed and rates remain low at <10 m/Ma during most of the late Cretaceous and Cenozoic. The conjugate margin of Argentina/Uruguay displays more gradual subsidence throughout the Cretaceous, consistently averaging a moderate 15-30m/Ma. By the end of this stage there is a subsequent increase to 25-60 m/Ma within the last 20 Ma, interpreted to reflect lithospheric loading due to increased sedimentation rates during the Cenozoic. This increase in subsidence rate is not seen in the African conjugate section where the majority of sediments bypassed the highly aggraded Cretaceous shelf. Initially greater on the Brazilian margin compared to Namibia, here both margins exhibit moderate-steep subsidence curves until 65-55 Ma where there is reduced subsidence during much of the Late Cretaceous until 20 Ma.

Contour mapping of relic structures in the Precambrian basement of the Reelfoot rift, North American midcontinent

USGS Publications Warehouse

Dart, R.L.; Swolfs, H.S.

1998-01-01

A new contour map of the basement of the Reelfoot rift constructed from drill hole and seismic reflection data shows the general surface configuration as well as several major and minor structural features. The major features are two asymmetric intrarift basins, bounded by three structural highs, and the rift margins. The basins are oriented normal to the northeast trend of the rift. Two of the highs appear to be ridges of undetermined width that extend across the rift. The third high is an isolated dome or platform located between the basins. The minor features are three linear structures of low relief oriented subparallel to the trend of the rift. Two of these, located within the rift basins, may divide the rift basins into paired subbasins. These mapped features may be the remnants of initial extensional rifting, half graben faulting, and basement subsidence. The rift basins are interpreted as having formed as opposing half graben, and the structural highs are interpreted as having formed as associated accommodation zones. Some of these features appear to be reactivated seismogenic structures within the modem midcontinent compressional stress regime. A detailed knowledge of the geometries of the Reelfoot rift's basement features, therefore, is essential when evaluating their seismic risk potential.

Flooding and subsidence in the Thames Gateway: impact on insurance loss potential

NASA Astrophysics Data System (ADS)

Royse, Katherine; Horn, Diane; Eldridge, Jillian; Barker, Karen

2010-05-01

In the UK, household buildings insurance generally covers loss and damage to the insured property from a range of natural and human perils, including windstorm, flood, subsidence, theft, accidental fire and winter freeze. Consequently, insurers require a reasoned view on the likely scale of losses that they may face to assist in strategic planning, reinsurance structuring, regulatory returns and general risk management. The UK summer 2007 flood events not only provided a clear indication of the scale of potential losses that the industry could face from an individual event, with £3 billion in claims, but also identified a need for insurers and reinsurers to better understand how events may correlate in time and space, and how to most effectively use the computational models of extreme events that are commonly applied to reflect these correlations. In addition to the potential for temporal clustering of events such as windstorms and floods, there is a possibility that seemingly uncorrelated natural perils, such as floods and subsidence, may impact an insurer's portfolio. Where aggregations of large numbers of new properties are planned, such as in the Thames Gateway, consideration of the potential future risk of aggregate losses due to the combination of perils such as subsidence and flood is increasingly important within the insurance company's strategic risk management process. Whilst perils such as subsidence and flooding are generally considered independent within risk modelling, the potential for one event to influence the magnitude and likelihood of the other should be taken into account when determining risk level. In addition, the impact of correlated, but distinctive, loss causing events on particular property types may be significant, particularly if a specific property is designed to protect against one peril but is potentially susceptible to another. We suggest that flood events can lead to increased subsidence risk due to the weight of additional water and sediment, or rehydration of sediment under flood water. The latter mechanism may be particularly critical on sites where Holocene sediments are currently protected from flooding and are no longer subsiding. Holocene deposits tend to compress, either under their own weight or under a superimposed load such as made ground, built structures or flood water. If protected dry sediments become flooded in the future, subsidence would be expected to resume. This research project aims to investigate the correlation between flood hazards and subsidence hazards and the effect that these two sources of risk will have on insurance losses in the Thames Gateway. In particular, the research will explore the potential hydrological and geophysical drivers and links between flood and subsidence events within the Thames Gateway, assessing the potential for significant event occurrence within the timescales relevant to insurers. In the first part of the project we have identified flood risk areas within the Thames Gateway development zone which have a high risk of flooding and may be affected by renewed or increased subsidence. This has been achieved through the use of national and local-scale 2D and 3D geo-environmental information such as the Geosure dataset (e.g. swell-shrink, collapsible and compressible deposits data layers), PSI data, thickness of superficial and artificial land deposits, and flood potential data etc. In the second stage of the project we will investigate the hydrological and geophysical links between flooding and subsidence events on developed sites; quantify the insurance loss potential in the Thames Gateway from correlated flooding and subsidence events; consider how climate change will affect risk to developments in the Thames Gateway in the context of subsidence and flooding; and develop new ways of communicating and visualise correlated flood and subsidence risk to a range of stakeholders, including the insurance industry, planners, policy makers and the general public.

Great earthquakes and tsunamis of the past 2000 years at the Salmon River estuary, central Oregon coast, USA

USGS Publications Warehouse

Nelson, A.R.; Asquith, A.C.; Grant, W.C.

2004-01-01

Four buried tidal marsh soils at a protected inlet near the mouth of the Salmon River yield definitive to equivocal evidence for coseismic subsidence and burial by tsunami-deposited sand during great earthquakes at the Cascadia subduction zone. An extensive, landward-tapering sheet of sand overlies a peaty tidal-marsh soil over much of the lower estuary. Limited pollen and macrofossil data suggest that the soil suddenly subsided 0.3-1.0 m shortly before burial. Regional correlation of similar soils at tens of estuaries to the north and south and precise 14C ages from one Salmon River site imply that the youngest soil subsided during the great earthquake of 26 January A.D. 1700. Evidence for sudden subsidence of three older soils during great earthquakes is more equivocal because older-soil stratigraphy can be explained by local hydrographic changes in the estuary. Regional 14C correlation of two of the three older soils with soils at sites that better meet criteria for a great-earthquake origin is consistent with the older soils recording subsidence and tsunamis during at least two great earthquakes. Pollen evidence of sudden coseismic subsidence from the older soils is inconclusive, probably because the amount of subsidence was small (<0.5 m). The shallow depths of the older soils yield rates of relative sea-level rise substantially less than rates previously calculated for Oregon estuaries.

Formation of offshore tidal sand banks triggered by a gasmined bed subsidence

NASA Astrophysics Data System (ADS)

Roos, Pieter C.; Hulscher, Suzanne J. M. H.

2002-12-01

Offshore gasmining is an example of a human intervention with a morphological impact. On land, it is usually attended with a dish-like bed depression. We show that, if located at sea, such a bed depression can become morphodynamically active by triggering mechanisms related to tidal sand bank formation. To that end, a simple morphological model is considered which describes an erodible bed subject to a tidal wave in a shallow sea. The continuous subsidence is modelled by a sink term in the sediment balance. Then, a linear approximation is carried out to describe the bed evolution after the onset of subsidence. The results, presented in physical space, show that the subsidence triggers the formation of a sand bank pattern that gradually spreads around the centre of subsidence, at a rate that may go up to 160 m year -1, depending on the tidal transport rate and the tidal eccentricity. The dimension of the depression does not affect the spreading rate nor the orientation of the sand banks, but it does influence their spacing. The main conclusion is that the horizontal extent of the area influenced by the bed depression by far exceeds that of the direct subsidence, thus showing that bed depressions on land and at sea indeed behave in fundamentally different ways. The results suggest that nonlinear effects are worthwhile to be investigated in order to describe finite amplitude development of sand banks as well as the interaction between subsidence and bed forms.

Subsidence in the Nocturnal Boundary Layer.

NASA Astrophysics Data System (ADS)

Carlson, Merrilee A.; Stull, Roland B.

1986-08-01

Nights with clear skies and strong radiative cooling that favor the formation of statically stable nocturnal boundary layers (NBL) are also those nights most likely to have subsidence, because of the presence of synoptic high-pressure regions. The divergence associated with subsidence laterally removes some of the chilled nocturnal boundary layer air causing the NBL to not grow as rapidly as would otherwise be expected. An equivalent interpretation is that subsidence-induced heating partially counteracts the radiative and turbulent cooling.A new form of nocturnal integral depth scale, HT, is introduced that incorporates the heating and cooling contributions at night. This scale can be used with a variety of idealized temperature profile shapes, including slab, linear, and exponential. It is shown that observed values of subsidence for two case studies can reduce the NBL growth rate, as measured by HT/t, by 5 to 50% and can cause corresponding errors in the estimation of accumulated cooling unless there is a proper accounting of subsidence.Subsidence plays a very minor role close to the ground, but for the case studies presented here its heating rate increases with height and becomes of comparable magnitude to the cooling rates of turbulence and radiation within the top third of the NBL. Although no adequate measurements of horizontal advective effects were available for the case studies used here, it appears from an energy balance that advection must not be neglected because its magnitude can be as large as turbulence and radiation.

Evidence for Recent Extension and Volcanism inside the Southern Margin of Mare Frigoris

NASA Astrophysics Data System (ADS)

Albin, Edward F.; Harris, R. Scott

2014-11-01

We report the identification of possible recent volcanic activity inside the southern margin of Mare Frigoris. Evidence includes two elliptical constructs with associated dark flows found at 56.6° N, - 19.7° W, north of the La Condamine J impact crater. They were discovered on high resolution (0.5 m/pixel) LROC WAC and NAC imagery (e.g., M188379739R and M142393589L) by the first author while performing a systematic geologic overview of the area.The constructs occur along a 3.2 km lineament trending southwest to northwest. The southwestern construct is the largest, measuring approximately 1.4 km in diameter by 65 m in height while the northeastern structure measures 1.2 km wide by 40 m high. The summits appear to be concave and contain well-defined pits 190 m and 120 m in diameter, respectively, each encircled by a deposit of raised material. Distinct dark deposits, exhibiting flow lobes, emanate from the pits. In addition, rubbly, flow-like dark deposits are found sporadically along the flanks of each feature.We interpret these structures as low profile steep-sided volcanic domes. Hawke et al. (2014) discussed volcanic constructs in the eastern part of Mare Frigoris; however, the features described in this study appear to be significantly younger. The domes may represent upwelling along a localized rift. Continued extension on the flanks appears to have released discrete dark flows. Well-defined flows crossing the floors of summit pits appear to have flowed uphill. We suggest that the evacuation of the magma chambers beneath these flows caused subsidence, forming the pits and giving the illusion that the lava flowed up and over the rims. Although the age of these constructs and flows is unknown, the paucity of impact craters suggests that they are relatively young. These could represent very recent eruptions of evolved magma on the Moon, similar to those reported by Jolliff et al. (2011). References: B. R. Hawke et al., 2014, LPSC, 45, 1318. Jolliff et al., 2012, Nature Geoscience, 4, 566-571.

Imaging the Buried Chicxulub Crater with Gravity Gradients and Cenotes

NASA Astrophysics Data System (ADS)

Hildebrand, A. R.; Pilkington, M.; Halpenny, J. F.; Ortiz-Aleman, C.; Chavez, R. E.; Urrutia-Fucugauchi, J.; Connors, M.; Graniel-Castro, E.; Camara-Zi, A.; Vasquez, J.

1995-09-01

Differing interpretations of the Bouguer gravity anomaly over the Chicxulub crater, Yucatan Peninsula, Mexico, have yielded diameter estimates of 170 to 320 km. Knowing the crater's size is necessary to quantify the lethal perturbations to the Cretaceous environment associated with its formation. The crater's size (and internal structure) is revealed by the horizontal gradient of the Bouguer gravity anomaly over the structure, and by mapping the karst features of the Yucatan region. To improve our resolution of the crater's gravity signature we collected additional gravity measurements primarily along radial profiles, but also to fill in previously unsurveyed areas. Horizontal gradient analysis of Bouguer gravity data objectively highlights the lateral density contrasts of the impact lithologies and suppresses regional anomalies which may obscure the gravity signature of the Chicxulub crater lithologies. This gradient technique yields a striking circular structure with at least 6 concentric gradient features between 25 and 85 km radius. These features are most distinct in the southwest probably because of denser sampling of the gravity field. Our detailed profiles detected an additional feature and steeper gradients (up to 5 mGal/km) than the original survey. We interpret the outer four gradient maxima to represent concentric faults in the crater's zone of slumping as is also revealed by seismic reflection data. The inner two probably represent the margin of the central uplift and the peak ring and or collapsed transient cavity. Radial gradients in the SW quadrant over the inferred ~40 km-diameter central uplift (4) may represent structural "puckering" as revealed at eroded terrestrial craters. Gradient features related to regional gravity highs and lows are visible outside the crater, but no concentric gradient features are apparent at distances > 90 km radius. The marginal gradient features may be modelled by slump faults as observed in large complex craters on the other terrestrial planets. A modeled fault of 1.5 km displacement (slightly slumped block exterior and impact breccia interior) reproduces the steepest gradient feature. This model is incompatible with models that place these gradient features inside the collapsed transient cavity. Locations of the karst features of the northern Yucatan region were digitized from 1:50,000 topographic maps, which show most but not all the water-filled sinkholes (locally known as cenotes). A prominent ring of cenotes is visible over the crater that is spatially correlated to the outer steep gravity gradient feature. The mapped cenotes constitute an unbiased sampling of the region's karst surface features of >50 m diameter. The gradient maximum and the cenote ring both meander with amplitudes of up to 2 km. The wiggles in the gradient feature and the cenote distribution probably correspond to the "scalloping" observed at the headwall of terraces in large complex craters. A second partial cenote ring exterior to the southwest side of the main ring corresponds to a less-prominent gravity gradient feature. No concentric structure is observable in the distribution of karst features at radii >90 km. The cenote ring is bounded by the outer peripheral steep gradient feature and must be related to it; the slump faults must have been reactivated sufficiently to create fracturing in the overlying and much younger sediment. Long term subsidence, as found at other terrestrial craters is a possible mechanism for the reactivation. Such long term subsidence may be caused by differential compaction or thermal relaxation. Elevations acquired during gravity surveys show that the cenote ring also corresponds to a topographic low along some of its length that probably reflects preferential erosion.

Feature Selection for Evolutionary Commercial-off-the-Shelf Software: Studies Focusing on Time-to-Market, Innovation and Hedonic-Utilitarian Trade-Offs

ERIC Educational Resources Information Center

Kakar, Adarsh Kumar

2013-01-01

Feature selection is one of the most important decisions made by product managers. This three article study investigates the concepts, tools and techniques for making trade-off decisions of introducing new features in evolving Commercial-Off-The-Shelf (COTS) software products. The first article investigates the efficacy of various feature…

Allergic contact dermatitis from color film developers: clinical and histologic features.

PubMed

Brancaccio, R R; Cockerell, C J; Belsito, D; Ostreicher, R

1993-05-01

We evaluated two patients with allergic contact dermatitis that resulted from exposure to color film developers. A lichenoid eruption developed in one patient, whereas an eruption more characteristic of an acute spongiotic dermatitis developed in the second patient. Histologic findings in the first case were those of a "lichenoid dermatitis" but with features distinct from classic lichen planus. The biopsy specimens from the second patient showed a subacute spongiotic process with a bandlike infiltrate suggestive of an evolving lichenoid process. Contact allergy to color developers may result in eruptions similar to lichen planus. This process appears to evolve from an acute spongiotic dermatitis in its early phase to a lichenoid dermatitis in fully developed and more chronic forms. Although the histologic features are those of a "lichenoid" dermatitis, some features, such as the presence of spongiosis, eosinophils, and a less intense inflammatory infiltrate, may enable distinction between lichenoid allergic contact dermatitis and true lichen planus. In addition, clinicopathologic correlation with patch test results should permit accurate diagnosis in most cases.

Areas of ground subsidence due to geofluid withdrawal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimsrud, G.P.; Turner, B.L.; Frame, P.A.

1978-08-01

Detailed information is provided on four geothermal areas with histories of subsidence. These were selected on the basis of: physical relevance of subsidence areas to high priority US geothermal sites in terms of withdrawn geofluid type, reservoir depth, reservoir geology and rock characteristics, and overburden characteristics; and data completeness, quality, and availability. The four areas are: Chocolate Bayou, Raft River Valley, Wairakei, and the Geysers. (MHR)

Recent Subsidence and Erosion at Diverse Wetland Sites in the Southeastern Mississippi Delta Plain

USGS Publications Warehouse

Morton, Robert A.; Bernier, Julie C.; Kelso, Kyle W.

2009-01-01

A prior study (U.S. Geological Survey Open-File Report 2005-1216) examined historical land- and water-area changes and estimated magnitudes of land subsidence and erosion at five wetland sites in the Terrebonne hydrologic basin of the Mississippi delta plain. The present study extends that work by analyzing interior wetland loss and relative magnitudes of subsidence and erosion at five additional wetland sites in the adjacent Barataria hydrologic basin. The Barataria basin sites were selected for their diverse physical settings and their recent (post-1978) conversion from marsh to open water. Historical aerial photography, datum-corrected marsh elevations and water depths, sediment cores, and radiocarbon dates were integrated to evaluate land-water changes in the Mississippi delta plain on both historical and geological time scales. The thickness of the organic-rich sediments (peat) and the elevation of the stratigraphic contact between peat and underlying mud were compared at marsh and open-water sites across areas of formerly continuous marsh to estimate magnitudes of recent delta-plain elevation loss caused by vertical erosion and subsidence of the wetlands. Results of these analyses indicate that erosion exceeded subsidence at most of the study areas, although both processes have contributed to historical wetland loss. Comparison of these results with prior studies indicates that subsidence largely caused rapid interior wetland loss in the Terrebonne basin before 1978, whereas erosional processes primarily caused more gradual interior wetland loss in the Barataria basin after 1978. Decadal variations in rates of relative sea-level rise at a National Ocean Service tide gage, elevation changes between repeat benchmark-leveling surveys, and GPS height monitoring at three National Geodetic Survey Continuously Operating Reference Stations indicate that subsidence rates since the early 1990s are substantially lower than those previously reported and are similar in magnitude to time-averaged subsidence rates at geological time scales. The historical decrease in land-loss rates across the Mississippi delta plain generally is consistent with the recent decrease in subsidence rates within the same region.

Modeling misidentification errors in capture-recapture studies using photographic identification of evolving marks

USGS Publications Warehouse

Yoshizaki, J.; Pollock, K.H.; Brownie, C.; Webster, R.A.

2009-01-01

Misidentification of animals is potentially important when naturally existing features (natural tags) are used to identify individual animals in a capture-recapture study. Photographic identification (photoID) typically uses photographic images of animals' naturally existing features as tags (photographic tags) and is subject to two main causes of identification errors: those related to quality of photographs (non-evolving natural tags) and those related to changes in natural marks (evolving natural tags). The conventional methods for analysis of capture-recapture data do not account for identification errors, and to do so requires a detailed understanding of the misidentification mechanism. Focusing on the situation where errors are due to evolving natural tags, we propose a misidentification mechanism and outline a framework for modeling the effect of misidentification in closed population studies. We introduce methods for estimating population size based on this model. Using a simulation study, we show that conventional estimators can seriously overestimate population size when errors due to misidentification are ignored, and that, in comparison, our new estimators have better properties except in cases with low capture probabilities (<0.2) or low misidentification rates (<2.5%). ?? 2009 by the Ecological Society of America.

Cone Penetration Testing, a new approach to quantify coastal-deltaic land subsidence by peat consolidation

NASA Astrophysics Data System (ADS)

Koster, Kay; Erkens, Gilles; Zwanenburg, Cor

2016-04-01

It is undisputed that land subsidence threatens coastal-deltaic lowlands all over the world. Any loss of elevation (on top of sea level rise) increases flood risk in these lowlands, and differential subsidence may cause damage to infrastructure and constructions. Many of these settings embed substantial amounts of peat, which is, due to its mechanically weak organic composition, one of the main drivers of subsidence. Peat is very susceptible to volume reduction by loading and drainage induced consolidation, which dissipates pore water, resulting in a tighter packing of the organic components. Often, the current state of consolidation of peat embedded within coastal-deltaic subsidence hotspots (e.g. Venice lagoon, Mississippi delta, San Joaquin delta, Kalimantan peatlands), is somewhere between its initial (natural) and maximum compressed stage. Quantifying the current state regarding peat volume loss, is of utmost importance to predict potential (near) future subsidence when draining or loading an area. The processes of subsidence often afflict large areas (>103 km2), thus demanding large datasets to assess the current state of the subsurface. In contrast to data describing the vertical motions of the actual surface (geodesy, satellite imagery), subsurface information applicable for subsidence analysis are often lacking in subsiding deltas. This calls for new initiatives to bridge that gap. Here we introduce Cone Penetration Testing (CPT) to quantify the amount of volume loss peat layers embedded within the Holland coastal plain (the Netherlands) experienced. CPT measures soil mechanical strength, and hundreds of thousands of CPTs are conducted each year on all continents. We analyzed 28 coupled CPT-borehole observations, and found strong empirical relations between volume loss and increased peat mechanical strength. The peat lost between ~20 - 95% of its initial thickness by dissipation of excess pore water. An increase in 0.1 - 0.4 MPa of peat strength is accountable for 20 - 75 % of the volume loss, and 0.4 - 0.7 MPa for 75 - 95 % volume loss. This indicates that large amounts of volume by water dissipation has to be lost, before peat experiences a serious increase in strength, which subsequently continuous to increase with only small amount of volume loss. To demonstrate the robustness of our approach to the international field of land subsidence, we applied the obtained empirical relations to previously published CPT logs deriving from the peat-rich San Joaquin-Sacramento delta and the Kalimantan peatlands, and found volume losses that correspond with previously published results. Furthermore, we used the obtained results to predict maximum surface lowering for these areas by consolidation. In conclusion, these promising results and its worldwide popularity yielding large datasets, open the door for CPT as a generic method to contribute to quantifying the imminent threat of coastal-deltaic land subsidence.

Subsurface mapping of the Ross Island flexural basin, southwest Antarctica

NASA Astrophysics Data System (ADS)

Wenman, Christopher P.

Ross Island is a post-Miocene (< 4.6 Ma) volcanic island located in the Ross Sea region of southwest Antarctica. This region of Antarctica borders the western edge of the West Antarctic Rift System, along the Transantarctic Mountain front. Marine and over-ice multi-channel seismic reflection surveys and borehole studies targeting the Ross Sea region over the last 30+ years have been used in this study to develop a seismic stratigraphic model of the development and evolution of the Ross Island flexural basin. Four key stratigraphic horizons were identified and mapped to fully capture the basin-fill, as well as strata lying above and below the flexural basin. From oldest to youngest these horizons are named RIB-m, RIM-g, RIM-b and RIB-r. Time structure, isochron and isochore maps were created for the horizons and the stratigraphic intervals they bound. The seismic stratigraphic record shows the Ross Island flexural moat formation post-dates the main tectonic subsidence phase within the Victoria Land Basin. The maps presented here are the first to fully illustrate the evolution of the Ross Island flexural basin. The maps highlight depositional patterns of two distinct periods of flexural subsidence and basin-filling superimposed on the older N-S trending Victoria Land Basin depocenter. Two units of flexural basin fill, Unit FFI between horizons RIM-g and RIM-b (the oldest flexural basin fill), and Unit FFII between horizons RIM-b and RIB-r (the youngest flexural basin fill) are associated with the two periods of flexural subsidence. Flexural moat subsidence and subsequent filling occurred episodically during periods of active volcanism on the island. Unit FFI is estimated to range from ca. 4 to 2 Ma, corresponding with formation of the Mt. Bird volcanic edifice on Ross Island. Unit FFII ranges in age from ca. 2 to 1 Ma, and is related to Mt. Terror, Mt. Erebus, and Hut Point Peninsula volcanism. The isochore maps suggest the depocenter of the flexural basin during both time intervals was located north of the island, instead of directly beneath the Ross Island topographic load. Factors contributing to the northerly location of the depocenter include i) volcanic loading by McMurdo Volcanic Group subsea volcanic features north of the island, ii) partial compensation of the main Ross Island load by low-density, partially molten rock beneath the island, iii) extensional faulting within the Terror Rift, and iv) seaward-thickening shelf sediments transported from the Ross Ice Shelf. The seismic data show that the onset of filling of the flexural moat around Ross Island coincided with the end of ice grounding events in the area. We infer that this was caused by flexural subsidence of the seafloor to accommodate the Ross Island load.

Slab roll-back and trench retreat as controlling factor for basin subsidence in southern Central America

NASA Astrophysics Data System (ADS)

Brandes, Christian; Winsemann, Jutta

2015-04-01

Slab roll-back and trench retreat are important factors for basin subsidence, magma generation and volcanism in arc-trench systems. Based on the sedimentary and tectonic record of the southern Central American island-arc we conclude that repeated phases of slab roll-back and trench retreats occurred the arc-trench system since the Late Cretaceous. These trench retreats were most probably related to the subduction of oceanic plateaus and seamounts and effected both the fore-arc and back-arc evolution. We used numerical basin modelling techniques to analyse the burial history of fore-arc and back-arc basins in Central America and combined the results with field data of the sedimentological evolution of the basin-fills. From the basin models, geohistory curves were extracted for the fore-arc and back-arc basins to derive the subsidence evolution. The Sandino Fore-arc Basin is characterized by low subsidence during the first 40 Myr. Since the Late Cretaceous the basin has a linear moderate subsidence with a phase of accelerated subsidence in the Oligocene. In the North and South Limón Back-arc Basin, subsidence started at approximately the same time as in the Sandino Fore-arc Basin. The North and South Limón Basins show a linear subsidence trend in the Paleocene and Eocene. Evidence for trench retreats is given by pulses of uplift in the outer-arc area, followed by subsidence in both the fore-arc and back-arc basins. The first slab roll-back probably occurred during the Early Paleocene. This is indicated by the collapse of carbonate platforms, and the re-deposition of large carbonate blocks into deep-water turbidites. A new pulse of uplift or decreased subsidence, respectively during the Late Eocene is attributed to subduction of rough crust. A subsequent slab detachment and the establishment of a new subduction zone further westward was described by Walther et al. (2000). Strong uplift affected the entire fore-arc area, which led to the deposition of very coarse-grained deepwater channel-levee complexes in the Sandino Fore-arc Basin. The channel-fills are rich in reworked shallow-water carbonates that points to strong uplift of the inner fore-arc. A subsequent trench retreat is indicated by an increased subsidence during the Early Oligocene in the Sandino Fore-arc Basin and the collapse of the Barra Honda carbonate platform in North Costa Rica. Another trench retreat might have occurred in Miocene times (Cailleau and Oncken, 2008). A phase of higher subsidence from 18 to 13 Ma is documented in the geohistory curve of the North Limon Back-arc Basin. After a short pulse of uplift the subsidence increased to approx. 300 m/myr (Brandes et al., 2008). References: Brandes C., Astorga A., Littke R. and Winsemann J. (2008) Basin modelling of the Limón Back-arc Basin (Costa Rica): burial history and temperature evolution of an island-arc related basin system. Basin Research 20, 1, 119-142. Cailleau, B. and Oncken, O. (2008) Past forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat. Geochemistry, Geophysics, Geosystems 9, Q07S24, doi:10.1029/2007GC001754. Walther, C.H.E., Flueh, E.R., Ranero, C.R., von Huene, R. and Strauch, W. (2000) Crustal structure across the Pacific margin of Nicaragua: evidence for ophiolithic basement and a shallow mantle sliver. Geophysical Journal International 141, 759-777.

Subsidence Rates in Southeast Texas as Determined by RTK GNSS Measurements of Preexisting Survey Markers

NASA Astrophysics Data System (ADS)

Kruger, J. M.

2013-12-01

This study determines the rates of subsidence or uplift in coastal areas of SE Texas by comparing recent GNSS measurements to the original orthometric heights of previously installed National Geodetic Survey (NGS) benchmarks. Understanding subsidence rates in coastal areas of SE Texas is critical when determining its vulnerability to local sea level rise and flooding, as well as for accurate survey control. The counties covered are Chambers, Galveston, Hardin, Jefferson, Liberty, Orange, and parts of Jasper and Newton counties. These counties lie between an earlier subsidence study conducted in Louisiana and an ongoing subsidence study of several counties around the Houston metropolitan area. The resurveying methods used in this RTK GNSS study allow a large area to be covered relatively quickly with enough detail to determine subsidence rates that are averaged over several decades. This information can be used to place more targeted GNSS observation stations in areas that appear to be rapidly subsiding. By continuously, or periodically, measuring the elevations at these targeted stations, current subsidence rates can be determined more accurately and at lower cost than by scattering a large number of GNSS stations over a wide area. This study was conducted using a Trimble R8 GNSS system on all NGS benchmarks that were found in the study area. Differential corrections were applied in real time using a VRS network of base stations. This system yields a nominal vertical accuracy of 1.5 to 2.0 cm for each 2 to 5 minute reading. Usually three of these readings were measured on each benchmark and averaged for the final result. A total of 367 benchmarks were resurveyed, most of which were suitable for vertical change rate calculations. Original NGS elevations were subtracted from the new elevations and divided by the time between the two elevation measurements to determine the average subsidence or uplift rate of the benchmark. Benchmarks used for determining the vertical change rates were monumented between1931 and 2006, thus yielding rates averaged for 5 to 80 years. Besides the errors inherent in RTK GNSS measurements, other sources of error for vertical change rates include inaccuracies in the original elevations published by the NGS and uncertainties about the year in which those original elevations were measured. Initial results show as much as -0.86 m of subsidence over a 58 year period on one benchmark in Jefferson County 30 km north of the coast, and up to +0.23 m of uplift over a 60 year period on one benchmark in Jasper County approximately 130 km north of the coast. Overall, preliminary results of the study show near zero vertical change rates to a maximum of -15.3 mm/yr subsidence in Chambers, Galveston, Liberty, and Jefferson counties, with the highest rates of subsidence in Jefferson and Chambers counties. Parts of Galveston, Orange, and Jasper counties show subsidence rates up to -9.1 mm/yr, but also show uplift rates up to +4.8 mm/yr. Potential causes of vertical change in the study area include expansion or contraction of near-surface clays due to changes in water content, compaction of near-surface to deeper sediments, growth faulting, groundwater, oil, or natural gas extraction or injection, and to a much smaller extent, tectonic effects.

The Changing Face of the Novel

ERIC Educational Resources Information Center

Serafini, Frank; Blasingame, James

2012-01-01

This article uses Dresang's dimensions of radical change to call attention to the evolving structures and features of novels for young readers being published today. The controversial topics and elaborate design features contained in contemporary novels, for example, the expansion of dystopic fiction, the disruption of traditional narrative…

Economic Modeling and Analysis of Educational Vouchers

ERIC Educational Resources Information Center

Epple, Dennis; Romano, Richard

2012-01-01

The analysis of educational vouchers has evolved from market-based analogies to models that incorporate distinctive features of the educational environment. These distinctive features include peer effects, scope for private school pricing and admissions based on student characteristics, the linkage of household residential and school choices in…

Estimating Aquifer Properties in the San Joaquin Basin, California, through the Analysis of InSAR Data

NASA Astrophysics Data System (ADS)

Smith, R. G.; Knight, R. J.; Zebker, H. A.; Farr, T. G.; Liu, Z.; Chen, J.; Crews, J.; Reeves, J.

2015-12-01

Increased groundwater withdrawal in the San Joaquin Valley, California, due to recent droughts has over-stressed many parts of the aquifer system, resulting in widespread aquifer compaction and land subsidence. Using Interferometric Synthetic Aperture Radar, or InSAR, we measure the magnitude of land subsidence to be as much as 20 cm/year for the period from 2007-2011. By comparing the observed subsidence with current and historic groundwater levels, we estimate that 90% of the observed subsidence is inelastic, or not recoverable. Due to delayed drainage in thick aquitards, we find that the majority (>95%) of compaction is caused by thin clay lenses within the upper and lower aquifers, which agrees with previous studies in the area. We use representative skeletal storage coefficients from previous studies in conjunction with observed subsidence and groundwater levels in a 1-dimensional vertical diffusion model to estimate the effective vertical hydraulic conductivity of the aquifer, and determine it is on the order of 1×10-6 cm/second.

Monitoring land subsidence in Sacramento Valley, California, using GPS

USGS Publications Warehouse

Blodgett, J.C.; Ikehara, M.E.; Williams, Gary E.

1990-01-01

Land subsidence measurement is usually based on a comparison of bench-mark elevations surveyed at different times. These bench marks, established for mapping or the national vertical control network, are not necessarily suitable for measuring land subsidence. Also, many bench marks have been destroyed or are unstable. Conventional releveling of the study area would be costly and would require several years to complete. Differences of as much as 3.9 ft between recent leveling and published bench-mark elevations have been documented at seven locations in the Sacramento Valley. Estimates of land subsidence less than about 0.3 ft are questionable because elevation data are based on leveling and adjustment procedures that occured over many years. A new vertical control network based on the Global Positioning System (GPS) provides highly accurate vertical control data at relatively low costs, and the survey points can be placed where needed to obtain adequate areal coverage of the area affected by land subsidence.

Global climate change and local land subsidence exacerbate inundation risk to the San Francisco Bay Area

PubMed Central

Shirzaei, Manoochehr; Bürgmann, Roland

2018-01-01

The current global projections of future sea level rise are the basis for developing inundation hazard maps. However, contributions from spatially variable coastal subsidence have generally not been considered in these projections. We use synthetic aperture radar interferometric measurements and global navigation satellite system data to show subsidence rates of less than 2 mm/year along most of the coastal areas along San Francisco Bay. However, rates exceed 10 mm/year in some areas underlain by compacting artificial landfill and Holocene mud deposits. The maps estimating 100-year inundation hazards solely based on the projection of sea level rise from various emission scenarios underestimate the area at risk of flooding by 3.7 to 90.9%, compared with revised maps that account for the contribution of local land subsidence. Given ongoing land subsidence, we project that an area of 125 to 429 km2 will be vulnerable to inundation, as opposed to 51 to 413 km2 considering sea level rise alone. PMID:29536042

Continuous Spectrum of Crustal Structures and Spreading Processes from Volcanic Rifted Margins to Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Karson, J. A.

2016-12-01

Structures generated by seafloor spreading in oceanic crust (and ophiolites) and thick oceanic crust of Iceland show a continuous spectrum of features that formed by similar mechanisms but at different scales. A high magma budget near the Iceland hotspot generates thick (40-25 km) mafic crust in a plate boundary zone about 50 km wide. The upper crust ( 10 km thick) is constructed by the subaxial subsidence and thickening of lavas fed by dense dike swarms over a hot, weak lower crust to produce structures analogous to seaward-dipping reflectors of volcanic rifted margins. Segmented rift zones propagate away from the hotspot creating migrating transform fault zones, microplate-like crustal blocks and rift-parallel strike-slip faults. These structures are decoupled from the underlying lower crustal gabbroic rocks that thin by along-axis flow that reduces the overall crustal thickness and smooths-out local crustal thickness variations. Spreading on mid-ocean ridges with high magma budgets have much thinner crust (10-5 km) generated at a much narrower (few km) plate boundary zone. Subaxial subsidence accommodates the thickening of the upper crust of inward-dipping lavas and outward-dipping dikes about 1-2 km thick over a hot weak lower crust. Along-axis (high-temperature ductile and magmatic) flow of lower crustal material may help account for the relatively uniform seismic thickness of oceanic crust worldwide. Spreading along even slow-spreading mid-ocean ridges near hotspots (e.g., the Reykjanes Ridge) probably have similar features that are transitional between these extremes. In all of these settings, upper crustal and lower crustal structures are decoupled near the plate boundary but eventually welded together as the crust ages and cools. Similar processes are likely to occur along volcanic rifted margins as spreading begins.

Earth observations taken by the Expedition 14 crew

NASA Image and Video Library

2006-11-18

ISS014-E-08179 (18 Nov. 2006) --- New Orleans, Louisiana is featured in this image photographed by an Expedition 14 crewmember on the International Space Station. The location of New Orleans, in a shallow depression within unconsolidated deltaic sediments, makes it particularly vulnerable to subsidence and increased likelihood of flooding. The average elevation of metropolitan New Orleans is 1.8 meters below sea level, and a complicated system of levees, pumps, and upstream control structures on the Mississippi River is necessary to maintain dry conditions in the city. The ground subsidence occurs from groundwater withdrawal, reduction of sediment delivery by the Mississippi River, and land use changes (such as draining of wetlands) associated with continuing development. The low areas can be flooded by river floods, storm surges, or failure of levees holding back surrounding lake waters - as demonstrated catastrophically during Hurricane Katrina in 2005. Sunglint accentuates the wetland setting of New Orleans in this image by highlighting the numerous lakes, pond, and rivers (in various shades of silver-gray) surrounding the city. The view was acquired by a crewmember looking southwest from the station, which was located over north-central Alabama at the time this image was taken. Lake Pontchartrain borders New Orleans to the north, and the Lake Pontchartrain Causeway (36 kilometers in length) appears as a dark linear feature against the lake surface. Variations in surface water coloration to the east and west of the Causeway reflect the dynamics of the surface waters (including surface currents and wind-induced roughening). The patterns are made visible by the presence of surfactants on the water surface. Low cloud cover produces a blue-gray haze visible at lower left.

Mine design: Long term effects of high extraction mining

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeran, P.W.

1996-12-31

A consideration when designing a high extraction coal mine is the effects that mining will have on the ground above the mine. This becomes particularly important when the surface has been improved or is inhabited. Surface owners are concerned about; when the effects will begin? how large will they be? and how long they will last? Each of these should be addressed by the designer. For more than a decade, the US Bureau of Mines (USBM) has been monitoring subsidence at various sites. Based upon the data gathered, some inferences may be made regarding the above stated questions. Essentially surfacemore » movement begins with undermining. The magnitude of the movements are proportional to the thickness extracted and the width of the mined area, and inversely proportional to the depth of the mine below surface. The duration of the subsidence process in the northern Appalachian Basin is approximately one year. The USBM has developed a computer model which predicts the final subsidence profile across a longwall panel in the northern Appalachian Coal Basin. USBM studies on the dynamic development of subsidence have shown that the magnitude of the deformations developed during the subsidence process never exceed those exhibited in the final subsidence profile. Use of the model will provide engineers with a starting point in the design process.« less

Determination of Soft Lithology Causes The Land Subsidence in Coastal Semarang City by Resistivity Methods

NASA Astrophysics Data System (ADS)

Widada, Sugeng; Saputra, Sidhi; Hariadi

2018-02-01

Semarang City is located in the northern coastal plain of Java which is geologically composed of alluvial deposits. The process of the sediment diagenesis has caused a land subsidence. On the other hand, the development of the industrial, service, education and housing sectors has increased the number of building significantly. The number of building makes the pressure of land surface increased, and finally, this also increased the rate of land subsidence. The drilling data indicates that not all layers of lithology are soft layers supporting the land subsidence. However, vertical distribution of the soft layer is still unclear. This study used Resistivity method to map out the soft zone layers of lithology. Schlumberger electrode configuration with sounding system method was selected to find a good vertical resolution and maximum depth. The results showed that the lithology layer with resistivity less than 3 ohm is a layer of clay and sandy clay that has the low bearing capacity so easily compressed by pressure load. A high land subsidence is happening in the thick soft layer. The thickness of that layer is smaller toward the direction of avoiding the beach. The improvement of the bearing capacity of this layer is expected to be a solution to the problem of land subsidence.

Ground deformation monitoring using small baseline DInSAR technique: A case study in Taiyuan City from 2003 to 2009

USGS Publications Warehouse

Wu, H.-A.; Zhang, Y.-H.; Chen, X.-Y.; Lu, T.; Du, J.; Sun, Z.-H.; Sun, G.-T.

2011-01-01

DInSAR technique based on time series of SAR images has been very popular to monitor ground stow deformation in recent years such as permanent scatterers (PS) method small baseline subsets (SBAS) method and coherent targets (CT) method. By taking advantage of PS method and CT method in this paper small baseline DTnSAR technique is used to investigate the ground deformation of Taiyuan City Shanxi Province from 2003 to 2009 by using 23 ENVISAT ASAR images. The experiment results demonstrate that: (1) during this period four significant subsidence centers have been developed in Taiyuan namely Xiayuan Wujiabu Xiaodian Sunjiazhai. The largest subsidence center is Sunjiazhai with an average subsidence rate of -77. 28 mm/a; (2) The subsidence of the old center Wanbolin has sHowed down. And the subsidence in the northern region has stopped and some areas even rebounded. (3) The change of subsidence centers indicates that the control measures of "closing wells and reducing exploitation" taken by the Taiyuan government has achieved initial effects. (4) The experiment results have been validated with leveling data and the acouracy is 2. 90 mm which shows that the small baseline DInSAR technique can be used to monitor urban ground deformation.

Hydromechanical coupling in fractured rock masses: mechanisms and processes of selected case studies

NASA Astrophysics Data System (ADS)

Zangerl, Christian

2015-04-01

Hydromechanical (HM) coupling in fractured rock play an important role when events including dam failures, landslides, surface subsidences due to water withdrawal or drainage, injection-induced earthquakes and others are analysed. Generally, hydromechanical coupling occurs when a rock mass contain interconnected pores and fractures which are filled with water and pore/fracture pressures evolves. In the on hand changes in the fluid pressure can lead to stress changes, deformations and failures of the rock mass. In the other hand rock mass stress changes and deformations can alter the hydraulic properties and fluid pressures of the rock mass. Herein well documented case studies focussing on surface subsidence due to water withdrawal, reversible deformations of large-scale valley flanks and failure as well as deformation processes of deep-seated rock slides in fractured rock masses are presented. Due to pore pressure variations HM coupling can lead to predominantly reversible rock mass deformations. Such processes can be considered by the theory of poroelasticity. Surface subsidence reaching magnitudes of few centimetres and are caused by water drainage into deep tunnels are phenomenas which can be assigned to processes of poroelasticity. Recently, particular focus was given on large tunnelling projects to monitor and predict surface subsidence in fractured rock mass in oder to avoid damage of surface structures such as dams of large reservoirs. It was found that surface subsidence due to tunnel drainage can adversely effect infrastructure when pore pressure drawdown is sufficiently large and spatially extended and differential displacements which can be amplified due to topographical effects e.g. valley closure are occurring. Reversible surface deformations were also ascertained on large mountain slopes and summits with the help of precise deformation measurements i.e. permanent GPS or episodic levelling/tacheometric methods. These reversible deformations are often in the range of millimetres to a very few centimetres and can be linked to annual groundwater fluctuations. Due to pore pressure variations HM coupling can influence seepage forces and effective stresses in the rock mass. Effective stress changes can adversely affect the stability and deformation behaviour of deep-seated rock slides by influencing the shear strength or the time dependent (viscous) material behaviour of the basal shear zone. The shear strength of active shear zones is often reasonably well described by Coulomb's law. In Coulomb's law the operative normal stresses to the shear surface/zone are effective stresses and hence pore pressures which should be taken into account reduces the shear strength. According to the time dependent material behaviour a few effective stress based viscous models exists which are able to consider pore pressures. For slowly moving rock slides HM coupling could be highly relevant when low-permeability clayey-silty shear zones (fault gouges) are existing. An important parameters therefore is the hydraulic diffusivity, which is controlled by the permeability and fluid-pore compressibility of the shear zone, and by fluid viscosity. Thus time dependent pore pressure diffusion in the shear zone can either control the stability condition or the viscous behaviour (creep) of the rock slide. Numerous cases studies show that HM coupling can effect deformability, shear strength and time dependent behaviour of fractured rock masses. A process-based consideration can be important to avoid unexpected impacts on infrastructures and to understand complex rock mass as well rock slide behaviour.

Causes of hot-spot wetland loss in the Mississippi delta plain

USGS Publications Warehouse

Morton, R.A.; Tiling, G.; Ferina, N.F.

2003-01-01

Field surveys and sediment cores were used to estimate marsh erosion and land subsidence at Madison Bay, a well-known wetland loss hot spot in coastal Louisiana. Former marshes of Madison Bay are under about 1 m of water. Nearly two-thirds of the permanent flooding was caused by rapid subsidence in the late 1960s, whereas the other third was caused by subsequent erosion. Subsidence rates near Madison Bay since the 1960s (???20 mm/yr) are an order of magnitude greater than deltaic subsidence rates averaged for the past 400-4000 yr (???2 mm/yr). The rapid acceleration and unexpected decline in wetland losses in the Mississippi delta plain are difficult to explain on the basis of most physical and biogeochemical processes. There are, however, close temporal and spatial correlations among regional wetland loss, high subsidence rates, and large-volume fluid production from nearby hydrocarbon fields. The decreased rates of wetland loss since the 1970s may be related to decreased rates of subsidence caused by significantly decreased rates of subsurface fluid withdrawal. Annual fluid production from the Lapeyrouse, Lirette, and Bay Baptiste fields that encompass Madison Bay accelerated in the 1960s, peaked about 1970, and then declined abruptly. Large decreases in pore pressure in the Lapeyrouse field have likely altered subsurface stresses and reactivated a major fault that coincides with the wetland loss hot spot. Therefore, wetland losses at Madison Bay can be closely linked to rapid subsidence and possible fault reactivation induced by long-term, large-volume hydrocarbon production. ?? 2003. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Potential inundated coastal area estimation in Shanghai with multi-platform SAR and altimetry data

NASA Astrophysics Data System (ADS)

Ma, Guanyu; Yang, Tianliang; Zhao, Qing; Kubanek, Julia; Pepe, Antonio; Dong, Hongbin; Sun, Zhibin

2017-09-01

As global warming problem is becoming serious in recent decades, the global sea level is continuously rising. This will cause damages to the coastal deltas with the characteristics of low-lying land, dense population, and developed economy. Continuously reclamation costal intertidal and wetland areas are making Shanghai, the mega city of Yangtze River Delta, more vulnerable to sea level rise. In this paper, we investigate the land subsidence temporal evolution of patterns and processes on a stretch of muddy coast located between the Yangtze River Estuary and Hangzou Bay with differential synthetic aperture radar interferometry (DInSAR) analyses. By exploiting a set of 31 SAR images acquired by the ENVISAT/ASAR from February 2007 to May 2010 and a set of 48 SAR images acquired by the COSMO-SkyMed (CSK) sensors from December 2013 to March 2016, coherent point targets as long as land subsidence velocity maps and time series are identified by using the Small Baseline Subset (SBAS) algorithm. With the DInSAR constrained land subsidence model, we predict the land subsidence trend and the expected cumulative subsidence in 2020, 2025 and 2030. Meanwhile, we used altimetrydata and densely distributed in the coastal region are identified (EEMD) algorithm to obtain the average sea level rise rate in the East China Sea. With the land subsidence predictions, sea level rise predictions, and high-precision digital elevation model (DEM), we analyze the combined risk of land subsidence and sea level rise on the coastal areas of Shanghai. The potential inundated areas are mapped under different scenarios.

Differences in coastal subsidence in southern Oregon (USA) during at least six prehistoric megathrust earthquakes

USGS Publications Warehouse

Milker, Yvonne; Nelson, Alan R.; Horton, Benjamin P.; Engelhart, Simon E.; Bradley, Lee-Ann; Witter, Robert C.

2016-01-01

Stratigraphic, sedimentologic (including CT 3D X-ray tomography scans), foraminiferal, and radiocarbon analyses show that at least six of seven abrupt peat-to-mud contacts in cores from a tidal marsh at Talbot Creek (South Slough, Coos Bay), record sudden subsidence (relative sea-level rise) during great megathrust earthquakes at the Cascadia subduction zone. Data for one contact are insufficient to infer whether or not it records a great earthquake—it may also have formed through local, non-seismic, hydrographic processes. To estimate the amount of subsidence marked by each contact, we expanded a previous regional modern foraminiferal dataset to 174 samples from six Oregon estuaries. Using a transfer function derived from the new dataset, estimates of coseismic subsidence across the six earthquake contacts vary from 0.31 m to 0.75 m. Comparison of subsidence estimates for three contacts in adjacent cores shows within-site differences of ≤0.10 m, about half the ±0.22 m error, although some estimates may be minimums due to uncertain ecological preferences for Balticammina pseudomacrescens in brackish environments and almost monospecific assemblages of Miliammina fusca on tidal flats. We also account for the influence of taphonomic processes, such as infiltration of mud with mixed foraminiferal assemblages into peat, on subsidence estimates. Comparisons of our subsidence estimates with values for correlative contacts at other Oregon sites suggest that some of our estimates are minimums and that Cascadia's megathrust earthquake ruptures have been heterogeneous over the past 3500 years.

Calibration of a Land Subsidence Model Using InSAR Data via the Ensemble Kalman Filter.

PubMed

Li, Liangping; Zhang, Meijing; Katzenstein, Kurt

2017-11-01

The application of interferometric synthetic aperture radar (InSAR) has been increasingly used to improve capabilities to model land subsidence in hydrogeologic studies. A number of investigations over the last decade show how spatially detailed time-lapse images of ground displacements could be utilized to advance our understanding for better predictions. In this work, we use simulated land subsidences as observed measurements, mimicking InSAR data to inversely infer inelastic specific storage in a stochastic framework. The inelastic specific storage is assumed as a random variable and modeled using a geostatistical method such that the detailed variations in space could be represented and also that the uncertainties of both characterization of specific storage and prediction of land subsidence can be assessed. The ensemble Kalman filter (EnKF), a real-time data assimilation algorithm, is used to inversely calibrate a land subsidence model by matching simulated subsidences with InSAR data. The performance of the EnKF is demonstrated in a synthetic example in which simulated surface deformations using a reference field are assumed as InSAR data for inverse modeling. The results indicate: (1) the EnKF can be used successfully to calibrate a land subsidence model with InSAR data; the estimation of inelastic specific storage is improved, and uncertainty of prediction is reduced, when all the data are accounted for; and (2) if the same ensemble is used to estimate Kalman gain, the analysis errors could cause filter divergence; thus, it is essential to include localization in the EnKF for InSAR data assimilation. © 2017, National Ground Water Association.

Spatial Analysis of Soil Subsidence in Peat Meadow Areas in Friesland in Relation to Land and Water Management, Climate Change, and Adaptation

NASA Astrophysics Data System (ADS)

Brouns, Karlijn; Eikelboom, Tessa; Jansen, Peter C.; Janssen, Ron; Kwakernaak, Cees; van den Akker, Jan J. H.; Verhoeven, Jos T. A.

2015-02-01

Dutch peatlands have been subsiding due to peat decomposition, shrinkage and compression, since their reclamation in the 11th century. Currently, subsidence amounts to 1-2 cm/year. Water management in these areas is complex and costly, greenhouse gases are being emitted, and surface water quality is relatively poor. Regional and local authorities and landowners responsible for peatland management have recognized these problems. In addition, the Netherlands Royal Meteorological Institute predicts higher temperatures and drier summers, which both are expected to enhance peat decomposition. Stakeholder workshops have been organized in three case study areas in the province of Friesland to exchange knowledge on subsidence and explore future subsidence rates and the effects of land use and management changes on subsidence rates. Subsidence rates were up to 3 cm/year in deeply drained parcels and increased when we included climate change in the modeling exercises. This means that the relatively thin peat layers in this province (ca 1 m) would shrink or even disappear by the end of the century when current practices continue. Adaptation measures were explored, such as extensive dairy farming and the production of new crops in wetter conditions, but little experience has been gained on best practices. The workshops have resulted in useful exchange of ideas on possible measures and their consequences for land use and water management in the three case study areas. The province and the regional water board will use the results to develop land use and water management policies for the next decades.

Thermal Evolution of the North-Central Gulf Coast

NASA Astrophysics Data System (ADS)

Nunn, Jeffrey A.; Scardina, Allan D.; Pilger, Rex H., Jr.

1984-12-01

The subsidence history of the North Louisiana Salt Basin, determined from well data, indicates that the region underwent extension during rifting and has since passively subsided due to conductive cooling of the lithosphere. Timing of the rifting event is consistent with opening of the Gulf of Mexico during Late Triassic to Early Jurassic time. Crustal extension by a factor of 1.5 to 2 was computed from "tectonic" subsidence curves. However, data from the early subsidence history are insufficient to distinguish between uniform and nonuniform extension of the lithosphere. The magnitude of extension is in good agreement with total sediment and crustal thicknesses from seismic refraction data in the adjacent Central Mississippi Salt Basin. The temperature distribution within the sediments is calculated using a simple heat conduction model. Temperature and subsidence effects of thermal insulation by overlying sediments are included. The computed temperature distribution is in good agreement with bottom hole temperatures measured in deep wells. Temperature histories predicted for selected stratigraphic horizons within the North Louisiana Salt Basin suggest that thermal conditions have been favorable for hydrocarbon generation in the older stata. Results from a two-dimensional heat conduction model suggest that a probable cause for the early formation of the adjacent uplifts is lateral heat conduction from the basin. Rapid extension of the lithosphere underneath areas with horizontal dimensions of 50-100 km produces extremely rapid early subsidence due to lateral heat conduction. The moderate subsidence rate observed in the North Louisiana Salt Basin during the Jurassic and Early Cretaceous suggests slow extension over a long period of time.

Subsidence Modeling of the Over-exploited Granular Aquifer System in Aguascalientes, Mexico

NASA Astrophysics Data System (ADS)

Solano Rojas, D. E.; Wdowinski, S.; Minderhoud, P. P. S.; Pacheco, J.; Cabral, E.

2016-12-01

The valley of Aguascalientes in central Mexico experiences subsidence rates of up to 100 [mm/yr] due to overexploitation of its aquifer system, as revealed from satellite-based geodetic observations. The spatial pattern of the subsidence over the valley is inhomogeneous and affected by shallow faulting. The understanding of the subsoil mechanics is still limited. A better understanding of the subsidence process in Aguascalientes is needed to provide insights for future subsidence in the valley. We present here a displacement-constrained finite-element subsidence model using Deltares iMOD (interactive MODeling), based on the USGS MODFLOW software. The construction of our model relies on 3 main inputs: (1) groundwater level time series obtained from extraction wells' hydrographs, (2) subsurface lithostratigraphy interpreted from well drilling logs, and (3) hydrogeological parameters obtained from field pumping tests. The groundwater level measurements were converted to pore pressure in our model's layers, and used in Terzaghi's equation for calculating effective stress. We then used the effective stresse along with the displacement obtained from geodetic observations to constrain and optimize five geo-mechanical parameters: compression ratio, reloading ratio, secondary compression index, over consolidation ratio, and consolidation coefficient. Finally, we use the NEN-Bjerrum linear stress model formulation for settlements to determine elastic and visco-plastic strain, accounting for the aquifer system units' aging effect. Preliminary results show higher compaction response in clay-saturated intervals (i.e. aquitards) of the aquifer system, as reflected in the spatial pattern of the surface deformation. The forecasted subsidence for our proposed scenarios show a much more pronounced deformation when we consider higher groundwater extraction regimes.

Subsidence Modeling of the Over-exploited Granular Aquifer System in Aguascalientes, Mexico

NASA Astrophysics Data System (ADS)

Solano Rojas, D. E.; Pacheco, J.; Wdowinski, S.; Minderhoud, P. S. J.; Cabral-Cano, E.; Albino, F.

2017-12-01

The valley of Aguascalientes in central Mexico experiences subsidence rates of up to 100 [mm/yr] due to overexploitation of its aquifer system, as revealed from satellite-based geodetic observations. The spatial pattern of the subsidence over the valley is inhomogeneous and affected by shallow faulting. The understanding of the subsoil mechanics is still limited. A better understanding of the subsidence process in Aguascalientes is needed to provide insights for future subsidence in the valley. We present here a displacement-constrained finite-element subsidence model, based on the USGS MODFLOW software. The construction of our model relies on 3 main inputs: (1) groundwater level time series obtained from extraction wells' hydrographs, (2) subsurface lithostratigraphy interpreted from well drilling logs, and (3) hydrogeological parameters obtained from field pumping tests. The groundwater level measurements were converted to pore pressure in our model's layers, and used in Terzaghi's equation for calculating effective stress. We then used the effective stress along with the displacement obtained from geodetic observations to constrain and optimize five geo-mechanical parameters: compression ratio, reloading ratio, secondary compression index, over consolidation ratio, and consolidation coefficient. Finally, we use the NEN-Bjerrum linear stress model formulation for settlements to determine elastic and visco-plastic strain, accounting for the aquifer system units' aging effect. Preliminary results show higher compaction response in clay-saturated intervals (i.e. aquitards) of the aquifer system, as reflected in the spatial pattern of the surface deformation. The forecasted subsidence for our proposed scenarios show a much more pronounced deformation when we consider higher groundwater extraction regimes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwahana, Go; Uchida, Masao; Liu, Lin

Thermokarst is the process of ground subsidence caused by either the thawing of ice-rich permafrost or the melting of massive ground ice. The consequences of permafrost degradation associated with thermokarst for surface ecology, landscape evolution, and hydrological processes have been of great scientific interest and social concern. Part of a tundra patch affected by wildfire in northern Alaska (27.5 km 2) was investigated here, using remote sensing and in situ surveys to quantify and understand permafrost thaw dynamics after surface disturbances. A two-pass differential InSAR technique using L-band ALOS-PALSAR has been shown capable of capturing thermokarst subsidence triggered by amore » tundra fire at a spatial resolution of tens of meters, with supporting evidence from field data and optical satellite images. We have introduced a calibration procedure, comparing burned and unburned areas for InSAR subsidence signals, to remove the noise due to seasonal surface movement. In the first year after the fire, an average subsidence rate of 6.2 cm/year (vertical) was measured. Subsidence in the burned area continued over the following two years, with decreased rates. The mean rate of subsidence observed in our interferograms (from 24 July 2008 to 14 September 2010) was 3.3 cm/year, a value comparable to that estimated from field surveys at two plots on average (2.2 cm/year) for the six years after the fire. These results suggest that this InSAR-measured ground subsidence is caused by the development of thermokarst, a thawing process supported by surface change observations from high-resolution optical images and in situ ground level surveys.« less

Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty

PubMed Central

2011-01-01

Background and purpose The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies. Methods Using a standardized impaction grafting technique with modifications, an initial group of 17 femurs underwent complete destructive impaction testing, allowing sequentially increased, controlled impaction forces to be applied until femoral fracture occurred. A second group of 8 femurs underwent impaction bone grafting at constant force, at an impaction frequency of 1 Hz or 10 Hz. An Exeter stem was cemented into the neomedullary canals. These constructs underwent subsidence testing simulating the first 2 months of postoperative weight bearing. Results No femurs fractured below an impaction force of 0.5 kN. 15/17 of the femurs fractured at or above 1.6 kN of applied force. In the second group of 8 femurs, all of which underwent femoral impaction grafting at 1.6 kN, there was no correlation between implant subsidence and frequency of impaction. Average subsidence was 3.2 (1–9) mm. Interpretation It is possible to calculate a force below which no fracture occurs in the embalmed human femur undergoing impaction grafting. Higher impaction frequency at constant force did not reduce rates of implant subsidence in this experiment. PMID:21689068

The association between price, competition, and demand factors on private sector anti-malarial stocking and sales in western Kenya: considerations for the AMFm subsidy.

PubMed

O'Meara, Wendy Prudhomme; Obala, Andrew; Thirumurthy, Harsha; Khwa-Otsyula, Barasa

2013-06-05

Households in sub-Saharan Africa are highly reliant on the retail sector for obtaining treatment for malaria fevers and other illnesses. As donors and governments seek to promote the use of artemisinin combination therapy in malaria-endemic areas through subsidized anti-malarials offered in the retail sector, understanding the stocking and pricing decisions of retail outlets is vital. A survey of all medicine retailers serving Bungoma East District in western Kenya was conducted three months after the launch of the AMFm subsidy in Kenya. The survey obtained information on each anti-malarial in stock: brand name, price, sales volume, outlet characteristics and GPS co-ordinates. These data were matched to household-level data from the Webuye Health and Demographic Surveillance System, from which population density and fever prevalence near each shop were determined. Regression analysis was used to identify the factors associated with retailers' likelihood of stocking subsidized artemether lumefantrine (AL) and the association between price and sales for AL, quinine and sulphadoxine-pyrimethamine (SP). Ninety-seven retail outlets in the study area were surveyed; 11% of outlets stocked subsidized AL. Size of the outlet and having a pharmacist on staff were associated with greater likelihood of stocking subsidized AL. In the multivariable model, total volume of anti-malarial sales was associated with greater likelihood of stocking subsidized AL and competition was important; likelihood of stocking subsidized AL was considerably higher if the nearest neighbour stocked subsidized AL. Price was a significant predictor of sales volume for all three types of anti-malarials but the relationship varied, with the largest price sensitivity found for SP drugs. The results suggest that helping small outlets overcome the constraints to stocking subsidized AL should be a priority. Competition between retailers and prices can play an important role in greater adoption of AL.

Persistent summit subsidence at Volcán de Colima, México, 1982 1999: strong evidence against Mogi deflation

NASA Astrophysics Data System (ADS)

Murray, John B.; Wooller, Luke K.

2002-09-01

This paper re-examines recent ground-deformation measurements at Volcán de Colima, Mexico, to test the hypothesis that the observed movements are in response to pressure changes within a sub-volcanic magma chamber, as suggested for other volcanoes by [Mogi (1958) Earthq. Res. Inst. 36, 99-134]. Measurements of vertical ground deformation across the summit dome complex of Volcán de Colima from a precise levelling network between 1982 and 1999, together with vertical and horizontal displacements derived from dual-frequency GPS measurements in 1994 and 1997, show continuous subsidence. The deformation pattern derived from the levelling shows that subsidence increases towards the summit. The closest stations to the summit (1.1 km distant) show a mean subsidence rate of 5 mm per year compared to the reference station at 2.3 km distance, which may be subsiding itself. Vertical displacements of individual stations since 1982 show that the subsidence has been fairly continuous. The GPS stations, which are distributed more widely and include some close to the edge of the active dome, confirm summit subsidence. The largest measured value, a decrease of 280 mm, or 93 mm subsidence per year, was obtained at the edge of the dome. Horizontal displacements measured during 1994-1997 also show the largest values at the summit, but these are much smaller than the vertical displacements, with the maximum rate of 23 mm per year recorded close to the dome. It is conclusively shown that these measured movements cannot be due to deflation of a buried Mogi source, as vertical and horizontal displacements for some stations are in contrary directions to those predicted by the model, and there is no consistent pattern to the horizontal movements. We attribute the measured deformation to downslope creep, settling and compaction of the edifice, gravitational spreading, or a combination of these processes.

Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowersox, J.R.; Shore, R.A.

1990-05-01

Surface subsidence due to reservoir compaction during production has been observed in many large oil fields. Subsidence is most obvious in coastal and offshore fields where inundation by the sea occurs. Well-known examples are Wilmington field in California and Ekofisk field in the North Sea. In South Belridge field, the Belridge Diatomite member of the late Miocene Reef Ridge Shale has proven prone to compaction during production. The reservoir, a high-porosity, low-permeability, highly compressive rock composed largely of diatomite and mudstone, is about 1,000 ft thick and lies at an average depth of 1,600 ft. Within the Belridge Diatomite, reservoirmore » compaction due to withdrawal of oil and water in Sec. 12, T28S, R20E, MDB and M, was noticed after casing failures in producing wells began occurring and tension cracks, enlarged by hydrocompaction after a heavy rainstorm were observed. Surface subsidence in Sec. 12 has been monitored since April 1987, through the surveying of benchmark monuments. The average annualized subsidence rate during 1987 was {minus}1.86 ft/yr, {minus}0.92 ft/yr during 1988, and {minus}0.65 ft/yr during 1989; the estimated peak subsidence rate reached {minus}7.50 ft/yr in July 1985, after 1.5 yrs of production from the Belridge Diatomite reservoir. Since production from the Belridge Diatomite reservoir commenced in February 1984, the surface of the 160-ac producing area has subsided about 12.5 ft. This equates to an estimated reservoir compaction of 30 ft in the Belridge Diatomite and an average loss of reservoir porosity of 2.4% from 55.2 to 52.8%. Injection of water for reservoir pressure maintenance in the Belridge diatomite began in June 1987, and has been effective in mitigating subsidence to current rates and repressurizing the reservoir to near-initial pressure. An added benefit of water injection has been improved recovery of oil from the Belridge Diatomite by waterflood.« less

Subsidence of Surtsey volcano, 1967-1991

USGS Publications Warehouse

Moore, J.G.; Jakobsson, S.; Holmjarn, J.

1992-01-01

The Surtsey marine volcano was built on the southern insular shelf of Iceland, along the seaward extension of the east volcanic zone, during episodic explosive and effusive activity from 1963 to 1967. A 1600-m-long, east-west line of 42 bench marks was established across the island shortly after volcanic activity stopped. From 1967 to 1991 a series of leveling surveys measured the relative elevation of the original bench marks, as well as additional bench marks installed in 1979, 1982 and 1985. Concurrent measurements were made of water levels in a pit dug on the north coast, in a drill hole, and along the coastline exposed to the open ocean. These surveys indicate that the dominant vertical movement of Surtsey is a general subsidence of about 1.1??0.3 m during the 24-year period of observations. The rate of subsidence decreased from 15-20 cm/year for 1967-1968 to 1-2 cm/year in 1991. Greatest subsidence is centered about the eastern vent area. Through 1970, subsidence was locally greatest where the lava plain is thinnest, adjacent to the flanks of the eastern tephra cone. From 1982 onward, the region closest to the hydrothermal zone, which is best developed in the vicinity of the eastern vent, began showing less subsidence relative to the rest of the surveyed bench marks. The general subsidence of the island probably results from compaction of the volcanic material comprising Surtsey, compaction of the sea-floor sediments underlying the island, and possibly downwarping of the lithosphere due to the laod of Surtsey. The more localized early downwarping near the eastern tephra cone is apparently due to greater compaction of tephra relative to lava. The later diminished local subsidence near the hydrothermal zone is probably due to a minor volume increase caused by hydrous alteration of glassy tephra. However, this volume increase is concentrated at depth beneath the bottom of the 176-m-deep cased drillhole. ?? 1992 Springer-Verlag.

Backward modelling of the subsidence evolution of the Colorado Basin, offshore Argentina and its relation to the evolution of the conjugate Orange Basin, offshore SW Africa

NASA Astrophysics Data System (ADS)

Dressel, Ingo; Scheck-Wenderoth, Magdalena; Cacace, Mauro

2017-10-01

In this study we focus on reconstructing the post-rift subsidence evolution of the Colorado Basin, offshore Argentina. We make use of detailed structural information about its present-day configuration of the sedimentary infill and the crystalline crust. This information is used as input in a backward modelling approach which relies on the assumption of local isostasy to reconstruct the amount of subsidence as induced by the sedimentary load through different time stages. We also attempt a quantification of the thermal effects on the subsidence as induced by the rifting, here included by following the uniform stretching model of lithosphere thinning and exponentially cooling through time. Based on the available information about the present-day geological state of the system, our modelling results indicate a rather continuous post-rift subsidence for the Colorado Basin, and give no significant evidence of any noticeable uplift phase. In a second stage, we compare the post-rift evolution of the Colorado Basin with the subsidence evolution as constrained for its conjugate SW African passive margin, the Orange Basin. Despite these two basins formed almost coevally and therefore in a similar large scale geodynamic context, their post-rift subsidence histories differ. Based on this result, we discuss causative tectonic processes likely to provide an explanation to the observed differences. We therefore conclude that it is most probable that additional tectonic components, other than the ridge-push from the spreading of the South Atlantic Ocean, are required to explain the observed differences in the subsidence of the two basins along the conjugate passive margins. Such additional tectonic components might be related to a dynamic mantle component in the form of either plume activity (Africa) or a subducting slab and the presence of an ongoing compressional stress system as revealed for different areas in South America.

The siting of a prison complex above an abandoned underground coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marino, G.G.

1997-12-31

This paper discusses in detail the process undertaken to mitigate the effects of any future mine subsidence on prison structures proposed above old abandoned underground workings. The site for a proposed prison complex purchased by the State of Indiana was located in west-central Indiana and was undermined by an old abandoned room and pillar mine. The original plan for construction consisted of one phase. Based on a study of the mine map and subsurface verification of the extent of mining it was determined that all prison buildings and important structures could be placed above solid coal to the north. Onemore » masonry building, however, was located within the potential draw zone of mine works which still contained significant mine voids. Based on empirical data the subsidence potential was estimated and the building was accordingly designed to be mine subsidence resistant. It was decided that a phase two prison complex should be constructed adjacent to and just south of the Phase I complex. This complex would be directly above the underground workings. The first stage of design was to minimize subsidence potential by positioning the exposure of significant structures to the subjacent mining assuming the mine map was sufficiently accurate. Subsequently, an extensive subsurface investigation program was then undertaken to: (1) ascertain whether or not mine areas where buildings would be located were already collapsed and thus only nominal, if any, subsidence could occur in the future; and (2) verify the presence of solid coal areas within the mine as indicated on the mine map. Based on all the site information gathered subsidence profiles were developed from an empirical data base of subsidence events in the Illinois Coal Basin. As a result of this work many structures on the site required no or nominal subsidence considerations.« less

Time Frequency Analysis of The Land Subsidence Monitored Data with Exploration Geophysics

NASA Astrophysics Data System (ADS)

Wang, Shang-Wei

2014-05-01

Taiwan geographic patterns and various industry water, caused Zhuoshui River Fan groundwater extraction of excess leads to land subsidence, affect the safety of high-speed railway traffic and public construction. It is necessary to do the deeply research on the reason and behavior of subsidence. All the related element will be confer including the water extracted groundwater that be used on each industry or the impact of climate change rainfall and the ground formation characteristics. Conducted a series of in situ measurements and monitoring data with Hilbert Huang Transform. Discussion of subsidence mechanism and estimate the future high-speed rail traffic may affect the extent of providing for future reference remediation. We investigate and experiment on the characteristic of land subsidence in Yun Lin area. The Hilbert-Huang Transform (HHT) and signal normalized are be used to discuss the physical meanings and interactions among the time series data of settlement, groundwater, pumping, rainfall and micro-tremor of ground. The broadband seismic signals of the Broadband Array in Taiwan for Seismology, (BATS) obtained near the Zhuoshui River (WLGB in Chia Yi, WGKB in Yun Lin and RLNB in Zhang Hua) were analyzed by using HHT and empirical mode decomposition (EMD) to discuss the micro-tremor characteristics of the settled ground. To compare among ten years series data of micro-tremor, groundwater and land subsidence monitoring wells, we can get more information about land subsidence. The electrical resistivity tomography (ERT) were performed to correlate the resistivity profile and borehole logging data at the test area. The relationships among resistivity, groundwater variation, and ground subsidence obtained from the test area have been discussed. Active and passive multichannel analysis of surface waves method (MASW) can calculate Poisson's ratio by using shear velocity and pressure velocity. The groundwater level can be presumed when Poisson's ratio arrive 0.5. We can know about undulate groundwater stages and variation of ground by more times measurements.

The association between price, competition, and demand factors on private sector anti-malarial stocking and sales in western Kenya: considerations for the AMFm subsidy

PubMed Central

2013-01-01

Background Households in sub-Saharan Africa are highly reliant on the retail sector for obtaining treatment for malaria fevers and other illnesses. As donors and governments seek to promote the use of artemisinin combination therapy in malaria-endemic areas through subsidized anti-malarials offered in the retail sector, understanding the stocking and pricing decisions of retail outlets is vital. Methods A survey of all medicine retailers serving Bungoma East District in western Kenya was conducted three months after the launch of the AMFm subsidy in Kenya. The survey obtained information on each anti-malarial in stock: brand name, price, sales volume, outlet characteristics and GPS co-ordinates. These data were matched to household-level data from the Webuye Health and Demographic Surveillance System, from which population density and fever prevalence near each shop were determined. Regression analysis was used to identify the factors associated with retailers’ likelihood of stocking subsidized artemether lumefantrine (AL) and the association between price and sales for AL, quinine and sulphadoxine-pyrimethamine (SP). Results Ninety-seven retail outlets in the study area were surveyed; 11% of outlets stocked subsidized AL. Size of the outlet and having a pharmacist on staff were associated with greater likelihood of stocking subsidized AL. In the multivariable model, total volume of anti-malarial sales was associated with greater likelihood of stocking subsidized AL and competition was important; likelihood of stocking subsidized AL was considerably higher if the nearest neighbour stocked subsidized AL. Price was a significant predictor of sales volume for all three types of anti-malarials but the relationship varied, with the largest price sensitivity found for SP drugs. Conclusion The results suggest that helping small outlets overcome the constraints to stocking subsidized AL should be a priority. Competition between retailers and prices can play an important role in greater adoption of AL. PMID:23738604

Subsidence of a volcanic basin by flexure and lower crustal flow: The eastern Snake River Plain, Idaho

NASA Astrophysics Data System (ADS)

McQuarrie, Nadine; Rodgers, David W.

1998-04-01

The Eastern Snake River Plain (ESRP) is a linear volcanic basin interpreted by many workers to reflect late Cenozoic migration of North America over the Yellowstone hotspot. Thermal subsidence of this volcanic province with respect to Yellowstone has been documented by several workers, but no one has characterized subsidence with respect to the adjacent Basin and Range Province. This paper documents crustal flexure along the northwest edge of the ESRP, uses flexure to model the dimensions of a dense load beneath the basin, and presents evidence in support of density-driven subsidence and lower crustal flow away from the basin. Crustal flexure adjacent to the ESRP is reflected by the attitudes of Mesozoic fold hinges and Neogene volcanic rocks. Fold hinges formed with a subhorizontal plunge and a trend perpendicular to the ESRP but now show a southward plunge near the ESRP of as much as 20°-25°. We present a contour map of equal fold plunges proximal to the ESRP that shows flexure is roughly parallel to and extends 10-20 km north of the average edge of the ESRP. Flexural profiles indicate the minimum amount of ESRP subsidence, with respect to the Basin and Range; subsidence ranges from 4.5 to 8.5 km. The structural contour map and published seismic and gravity data were used to develop and constrain flexural subsidence models. These models indicate the flexed crust is very weak (flexural parameter of 4-10 km), interpreted to be a result of the high heat flow of the ESRP. Assuming subsidence was induced by emplacement of a dense crustal layer beneath the ESRP, a midcrustal "sill" identified in previous seismic surveys is too wide and probably too thin to produce the measured flexure. New dimensions include a thickness of 17-25 km and a half width of 40-50 km, which place the edge of the sill beneath the edge of the ESRP. The dimensions of the ESRP sill are based on isostatic compensation in the lower crust because compensation in the asthenosphere requires an unreasonable sill thickness of 30+ km and because ESRP seismic, gravity, and heat flow data support lower crustal compensation. Density-driven lower crustal flow away from the ESRP is proposed to accommodate subsidence and maintain isostatic equilibrium. Timing of subsidence is constrained by ESRP exploratory wells, where 6.6 Ma rhyolites at a depth of 1.5 km indicate most subsidence occurred prior to their emplacement, and by strong spatial correlations between plunge contours and Quaternary volcanic rift zones. Two processes interpreted to contribute to the load include an extensive midcrustal mafic load emplaced at ˜10 Ma, which provided the heat source for the initial rhyolitic volcanism on the ESRP, and continuing, localized loads from dikes and sills associated with Quaternary basalts. Widespread ˜10 Ma magmatism and subsidence conflicts with simple time-transgressive migration of the Yellowstone hotspot, indicating a need for revision of the hotspot paradigm.

Anomalous Subsidence at Rifted Continental Margins: Distinguishing Mantle Dynamic Topography from Anomalous Oceanic Crustal Thickness

NASA Astrophysics Data System (ADS)

Cowie, L.; Kusznir, N. J.

2012-12-01

It has been proposed that some continental rifted margins have anomalous subsidence histories and that at breakup they were elevated at shallower bathymetries than the isostatic response of classical rift models (McKenzie 1978) would predict. The existence of anomalous syn or post breakup subsidence of this form would have important implications for our understanding of the geodynamics of continental breakup and rifted continental margin formation, margin subsidence history and the evolution of syn and post breakup depositional systems. We have investigated three rifted continental margins; the Gulf of Aden, Galicia Bank and the Gulf of Lions, to determine whether the oceanic crust in the ocean-continent transition of these margins has present day anomalous subsidence and if so, whether it is caused by mantle dynamic topography or anomalous oceanic crustal thickness. Residual depth anomalies (RDA) corrected for sediment loading, using flexural backstripping and decompaction, have been calculated by comparing observed and age predicted oceanic bathymetries in order to identify anomalous oceanic bathymetry and subsidence at these margins. Age predicted bathymetric anomalies have been calculated using the thermal plate model predictions from Crosby & McKenzie (2009). Non-zero sediment corrected RDAs may result from anomalous oceanic crustal thickness with respect to the global average, or from mantle dynamic uplift. Positive RDAs may result from thicker than average oceanic crust or mantle dynamic uplift; negative RDAs may result from thinner than average oceanic crust or mantle dynamic subsidence. Gravity inversion incorporating a lithosphere thermal gravity anomaly correction and sediment thickness from 2D seismic data has been used to determine Moho depth and oceanic crustal basement thickness. The reference Moho depths used in the gravity inversion have been calibrated against seismic refraction Moho depths. The gravity inversion crustal basement thicknesses together with Airy isostasy have been used to predict a "synthetic" gravity derived RDA. Sediment corrected RDA for oceanic crust in the Gulf of Aden are positive (+750m) indicating anomalous uplift with respect to normal subsidence. Gravity inversion predicts normal thickness oceanic crust and a zero "synthetic" gravity derived RDA in the oceanic domain. The difference between the positive sediment corrected RDA and the zero "synthetic" gravity derived RDA, implies that the anomalous subsidence reported in the Gulf of Aden is the result of mantle dynamic uplift. For the oceanic crust outboard of Galicia Bank both the sediment corrected RDA and the "synthetic" gravity derived RDA are negative (-800m) and of similar magnitude, indicating anomalous subsidence, which is the result of anomalously thin oceanic crust, not mantle dynamic topography. We conclude that there is negligible mantle dynamic topography influencing the Galicia Bank region. In the Gulf of Lions, gravity inversion predicts thinner than average oceanic crust. Both sediment corrected RDA (-1km) and "synthetic" gravity derived RDA (-500m) are negative. The more negative sediment corrected RDA compared with the "synthetic" gravity derived RDA implies that the anomalous subsidence in the Gulf of Lions is the result of mantle dynamic subsidence as well as thinner than average oceanic crust.

Some Features of Human Adolescence Viewed in Evolutionary Perspective.

ERIC Educational Resources Information Center

Weisfeld, G. E.; Berger, J. M.

1983-01-01

Focuses on some apparently evolved features of human adolescence and their possible functions, including the pubertal growth spurt, sexual size dimorphism and bimaturism, the greater aggressiveness of males, heightened concern with one's social standing and the factors affecting it, intergenerational friction, same-sex aggregations and solidarity,…

Blasting for abandoned-mine land reclamation (closure of individual subsidence features and erratic, undocumented underground coal-mine workings). Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Workman, J.L.; Thompson, J.

1991-01-01

The study has examined the feasibility of blasting for mitigating various abandoned mine land features on AML sites. The investigation included extensive field trial blasts at sites in North Dakota and Montana. A blasting technique was used that was based on spherical cratering concepts. At the Beulah, North Dakota site thirteen individual vertical openings (sinkholes) were blasted with the intent to fill the voids. The blasts were designed to displace material laterally into the void. Good success was had in filling the sinkholes. At the White site in Montana erratic underground rooms with no available documentation were collapsed. An aditmore » leading into the mine was also blasted. Both individual room blasting and area pattern blasting were studied. A total of eight blasts were fired on the one acre area. Exploration requirements and costs were found to be extensive.« less

Predictions and Verification of an Isotope Marine Boundary Layer Model

NASA Astrophysics Data System (ADS)

Feng, X.; Posmentier, E. S.; Sonder, L. J.; Fan, N.

2017-12-01

A one-dimensional (1D), steady state isotope marine boundary layer (IMBL) model is constructed. The model includes meteorologically important features absent in Craig and Gordon type models, namely height-dependent diffusion/mixing and convergence of subsiding external air. Kinetic isotopic fractionation results from this height-dependent diffusion which starts as pure molecular diffusion at the air-water interface and increases linearly with height due to turbulent mixing. The convergence permits dry, isotopically depleted air subsiding adjacent to the model column to mix into ambient air. In δD-δ18O space, the model results fill a quadrilateral, of which three sides represent 1) vapor in equilibrium with various sea surface temperatures (SSTs) (high d18O boundary of quadrilateral); 2) mixture of vapor in equilibrium with seawater and vapor in the subsiding air (lower boundary depleted in both D and 18O); and 3) vapor that has experienced the maximum possible kinetic fractionation (high δD upper boundary). The results can be plotted in d-excess vs. δ18O space, indicating that these processes all cause variations in d-excess of MBL vapor. In particular, due to relatively high d-excess in the descending air, mixing of this air into the MBL causes an increase in d-excess, even without kinetic isotope fractionation. The model is tested by comparison with seven datasets of marine vapor isotopic ratios, with excellent correspondence; >95% of observational data fall within the quadrilateral area predicted by the model. The distribution of observations also highlights the significant influence of vapor from the nearby converging descending air on isotopic variations in the MBL. At least three factors may explain the <5% of observations that fall slightly outside of the predicted region in both δD-δ18O and d-excess - δ18O space: 1) variations in seawater isotopic ratios, 2) variations in isotopic composition of subsiding air, and 3) influence of sea spray. The model can be used for understanding the effects of boundary layer processes and meteorological conditions on isotopic composition of vapor within, and vapor fluxes through the MBL, and how changes in moisture source regions affect the isotopic composition of precipitation. The model can be applied to modern as well as paleo- climate conditions.

Ostracoda (Crustacea) association and a new species (Dolerocypris anatolia nov. sp.) from the Pliocene-Pleistocene Afşin-Elbistan (Kahraman Maraş) Coal Basin of Turkey

NASA Astrophysics Data System (ADS)

Tunoǧlu, Cemal; Besbelli, Berk; Ertekin, İbrahim Kadri

2012-04-01

The Afşin-Elbistan Coal Basin, which is one of the largest and most important Pliocene-Pleistocene lignite basins of Turkey, is located in Eastern Anatolia. The basin was formed between two normal faults having NE-SW direction and these faults controlled both the sedimentation and the subsidence. The coal horizon of over 50 meters in thickness indicates the balance between the sedimentation and subsidence rates, and was preserved during peat deposition. Coals were generated in this extensive and shallow freshwater lake and evolved from the Pliocene to Pleistocene. Typical faunal and floral assemblages of this ancient Afşin-Elbistan freshwater lake are Ostracoda, Mollusca (Gastropoda and Pelecypoda), spore-pollen and Characeae (gyrogonites). Eleven Cypridoidea species were identified from the investigation area. Eight of them are already known (Candona neglecta Sars, Candona iliensis Mandelstam, Candona aff. candida (Müller), Pseudocandona compressa (Koch), Cyclocypris ovum (Jurine), Ilyocypris gibba (Ramdohr), Cypris pubera Müller, Heterocypris salina (Brady)), whereas three belong to open nomenclature — Candona sp. and Eucypris sp.; Dolerocypris anatolia nov. sp. is proposed as a new species. Dolerocypris Kaufmann is one of the largest genera among the freshwater Ostracoda. It has a very wide geographical distribution. Representatives of this genus are actively swimming species found in shallow zones of freshwater lakes and reported from small grassy water bodies with megascopic plants. Dolerocypris anatolia nov. sp. is recorded from core samples of the Pliocene-Pleistocene Afşin-Elbistan Coal Basin for the first time.

The cost of service quality improvements: tracking the flow of funds in social franchise networks in Myanmar

PubMed Central

2013-01-01

Introduction This paper examines the cost of quality improvements in Population Services International (PSI) Myanmar’s social franchise operations from 2007 to 2009. Methods The social franchise commodities studied were products for reproductive health, malaria, STIs, pneumonia, and diarrhea. This project applied ingredients based costing for labor, supplies, transport, and overhead. Data were gathered seven during key informant interviews with staff in the central Yangon office, examination of 3 years of payroll data, examination of a time motion study conducted by PSI, and spreadsheets recording the costs of acquiring and transporting supplies. Results In 2009 PSI Myanmar’s social franchise devoted $2.02 million towards a 94% reduction in commodity prices offered to its network of over 1700 primary care providers. These providers retained 1/3 of the subsidy as revenue and passed along the other 2/3 to their patients in the course of offering subsidized care for 1.5 million health episodes. In addition, PSI Myanmar devoted $2.09 million to support a team of franchise officers who conducted quality assurance for the private providers overseeing service quality and to distributing medical commodities. Conclusion In Myanmar, the social franchise operated by PSI spends roughly $1.00 in quality management and retailing for every $1.00 spent subsidizing medical commodities. Some services are free, but patients also pay fees for other lines of service. Overall patients contribute 1/6 as much as PSI does. Unlike other NGO’s, health services in social franchises like PSI are not all free to the patients, nor are the discounts uniformly applied. Discounts and subsidies evolve in response to public health concerns, market demand, providers’ cost structures as well as strategic objectives in maintaining the network and its portfolio of services. PMID:23826743

The cost of service quality improvements: tracking the flow of funds in social franchise networks in Myanmar.

PubMed

Bishai, David; LeFevre, Amnesty; Theuss, Marc; Boxshall, Matt; Hetherington, John D; Zaw, Min; Montagu, Dominic

2013-01-01

This paper examines the cost of quality improvements in Population Services International (PSI) Myanmar's social franchise operations from 2007 to 2009. The social franchise commodities studied were products for reproductive health, malaria, STIs, pneumonia, and diarrhea. This project applied ingredients based costing for labor, supplies, transport, and overhead. Data were gathered seven during key informant interviews with staff in the central Yangon office, examination of 3 years of payroll data, examination of a time motion study conducted by PSI, and spreadsheets recording the costs of acquiring and transporting supplies. In 2009 PSI Myanmar's social franchise devoted $2.02 million towards a 94% reduction in commodity prices offered to its network of over 1700 primary care providers. These providers retained 1/3 of the subsidy as revenue and passed along the other 2/3 to their patients in the course of offering subsidized care for 1.5 million health episodes. In addition, PSI Myanmar devoted $2.09 million to support a team of franchise officers who conducted quality assurance for the private providers overseeing service quality and to distributing medical commodities. In Myanmar, the social franchise operated by PSI spends roughly $1.00 in quality management and retailing for every $1.00 spent subsidizing medical commodities. Some services are free, but patients also pay fees for other lines of service. Overall patients contribute 1/6 as much as PSI does. Unlike other NGO's, health services in social franchises like PSI are not all free to the patients, nor are the discounts uniformly applied. Discounts and subsidies evolve in response to public health concerns, market demand, providers' cost structures as well as strategic objectives in maintaining the network and its portfolio of services.

Studies of Louisiana's Deltas and Wetlands using SAR

NASA Astrophysics Data System (ADS)

Jones, C. E.

2017-12-01

Sustainable coastal environments exist in delicate balance between subsidence, erosion, and sea level rise on one hand and accretion of sediment and retention of decomposing organic matter on the other. In this talk we present results from a series of studies using an airborne L-band SAR (UAVSAR) to measure changing conditions in the Mississippi River Delta and coastal wetlands of Louisiana. Change within the Mississippi River delta (MRD), which is a highly engineered environment, is contrasted to those in the Wax Lake Delta, a small, naturally evolving delta located to the west of the current-day lobe of the MRD. The UAVSAR studies provide evidence that in the MRD subsidence and erosion related to human activities are increasing risk of flooding, submergence, and land loss. These are not seen in the Wax Lake Delta, where new land is forming. We evaluate geomorphic and hydrologic changes In the Wax Lake Delta and wetlands hydrologically connected to the Wax Lake Outlet canal that are apparent on the timescales of the UAVSAR data set, which consists of both near-yearly acquisitions (2009-2016) and several series of repeat acquisitions in 2015 and 2016 capturing conditions across a tidal cycle. Using the yearly data, we observe the evolution of subaqueous channels and crevasses in the delta and changes in distributary channels within the wetlands. We use water level change derived from InSAR applied to the rapid repeat data acquired during different stages of a tidal cycle to study the natural pattern of water flux within the delta and the coastal wetlands. The studies, results, and plans for future work will be presented. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contracts with the California Dept. of Water Resources and with the National Aeronautics and Space Administration.

Three-dimensional modeling of pull-apart basins: implications for the tectonics of the Dead Sea Basin

USGS Publications Warehouse

Katzman, Rafael; ten Brink, Uri S.; Lin, Jian

1995-01-01

We model the three-dimensional (3-D) crustal deformation in a deep pull-apart basin as a result of relative plate motion along a transform system and compare the results to the tectonics of the Dead Sea Basin. The brittle upper crust is modeled by a boundary element technique as an elastic block, broken by two en echelon semi-infinite vertical faults. The deformation is caused by a horizontal displacement that is imposed everywhere at the bottom of the block except in a stress-free “shear zone” in the vicinity of the fault zone. The bottom displacement represents the regional relative plate motion. Results show that the basin deformation depends critically on the width of the shear zone and on the amount of overlap between basin-bounding faults. As the width of the shear zone increases, the depth of the basin decreases, the rotation around a vertical axis near the fault tips decreases, and the basin shape (the distribution of subsidence normalized by the maximum subsidence) becomes broader. In contrast, two-dimensional plane stress modeling predicts a basin shape that is independent of the width of the shear zone. Our models also predict full-graben profiles within the overlapped region between bounding faults and half-graben shapes elsewhere. Increasing overlap also decreases uplift near the fault tips and rotation of blocks within the basin. We suggest that the observed structure of the Dead Sea Basin can be described by a 3-D model having a large overlap (more than 30 km) that probably increased as the basin evolved as a result of a stable shear motion that was distributed laterally over 20 to 40 km.

Earth fissures and localized differential subsidence

USGS Publications Warehouse

Holzer, Thomas L.; Pampeyan, Earl H.

1981-01-01

Long linear tension cracks associated with declining groundwater levels at four sites in subsiding areas in south-central Arizona, Fremont Valley, California, and Las Vegas Valley, Nevada, occur near points of maximum convex-upward curvature in subsidence profiles oriented perpendicular to the cracks. Profiles are based on repeated precise vertical control surveys of lines of closely spaced bench marks. Association of these fissures with zones of localized differential subsidence indicates that linear earth fissures are caused by horizontal tensile strains probably resulting from localized differential compaction. Horizontal tensile strains across the fissures at the point of maximum convex-upward curvature, ranging from approximately 100 to 700 microstrains (0.01 to 0.07% per year), were indicated based on measurements with a tape or electronic distance meter.

A VHDL Core for Intrinsic Evolution of Discrete Time Filters with Signal Feedback

NASA Technical Reports Server (NTRS)

Gwaltney, David A.; Dutton, Kenneth

2005-01-01

The design of an Evolvable Machine VHDL Core is presented, representing a discrete-time processing structure capable of supporting control system applications. This VHDL Core is implemented in an FPGA and is interfaced with an evolutionary algorithm implemented in firmware on a Digital Signal Processor (DSP) to create an evolvable system platform. The salient features of this architecture are presented. The capability to implement IIR filter structures is presented along with the results of the intrinsic evolution of a filter. The robustness of the evolved filter design is tested and its unique characteristics are described.

Multi-gene phylogenetic analysis reveals the multiple origin and evolution of mangrove physiological traits through exaptation

NASA Astrophysics Data System (ADS)

Sahu, Sunil Kumar; Singh, Reena; Kathiresan, Kandasamy

2016-12-01

Mangroves are taxonomically diverse group of salt-tolerant, mainly arboreal, flowering plants that grow in tropical and sub-tropical regions and have adapted themselves to thrive in such obdurate surroundings. While evolution is often understood exclusively in terms of adaptation, innovation often begins when a feature adapted for one function is co-opted for a different purpose and the co-opted features are called exaptations. Thus, one of the fundamental issues is what features of mangroves have evolved through exaptation. We attempt to address these questions through molecular phylogenetic approach using chloroplast and nuclear markers. First, we determined if these mangroves specific traits have evolved multiple times in the phylogeny. Once the multiple origins were established, we then looked at related non-mangrove species for characters that could have been co-opted by mangrove species. We also assessed the efficacy of these molecular sequences in distinguishing mangroves at the species level. This study revealed the multiple origin of mangroves and shed light on the ancestral characters that might have led certain lineages of plants to adapt to estuarine conditions and also traces the evolutionary history of mangroves and hitherto unexplained theory that mangroves traits (aerial roots and viviparous propagules) evolved as a result of exaptation rather than adaptation to saline habitats.

Maximizing the Adjacent Possible in Automata Chemistries.

PubMed

Hickinbotham, Simon; Clark, Edward; Nellis, Adam; Stepney, Susan; Clarke, Tim; Young, Peter

2016-01-01

Automata chemistries are good vehicles for experimentation in open-ended evolution, but they are by necessity complex systems whose low-level properties require careful design. To aid the process of designing automata chemistries, we develop an abstract model that classifies the features of a chemistry from a physical (bottom up) perspective and from a biological (top down) perspective. There are two levels: things that can evolve, and things that cannot. We equate the evolving level with biology and the non-evolving level with physics. We design our initial organisms in the biology, so they can evolve. We design the physics to facilitate evolvable biologies. This architecture leads to a set of design principles that should be observed when creating an instantiation of the architecture. These principles are Everything Evolves, Everything's Soft, and Everything Dies. To evaluate these ideas, we present experiments in the recently developed Stringmol automata chemistry. We examine the properties of Stringmol with respect to the principles, and so demonstrate the usefulness of the principles in designing automata chemistries.

A classification of morphoseismic features in the New Madrid seismic zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knox, R.; Stewart, D.

1993-03-01

The New Madrid Seismic Zone (NMSZ) contains thousands of surface features distributed over 5,000 square miles in four states. These are attributable to some combination of (1) seismically-induced liquefaction (SIL), (2) secondary deformation, and (3) seismically-induced slope failures. Most of these features were produced by the 1811--12 series of great earthquakes, but some predate and some postdate 1811--12. Subsequent non-seismic factors, such as hydrologically-induced liquefaction (HIL), mechanically-induced liquefaction (MIL), human activities, mass wasting, eolian and fluvial processes have modified all of these features. Morphoseismic features are new landforms produced by earthquakes, or are pre-existing landforms modified by them. Involved aremore » complex interrelationships among several variables, including: (1) intensity and duration of seismic ground motion, (2) surface wave harmonics, (3) depth to water table, (4) depth to basement, (5) particle size, composition, and sorting of sediment making up the liquefied (LZ) and non-liquefied zones (NLZ), (6) topographic parameters, and (7) attitudes of beds and lenses susceptible to liquefaction. Morphoseismic features are depicted as results of a time-flow sequence initiated by primary basement disturbances which produce three major categories of surface response: secondary deformation, liquefaction and slope failure. Nine subcategories incorporate features produced by or resulting in: extruded sand, intruded sand, lateral spreading, faulting, subsidence of large areas, uplift of large areas, altered streams, coherent landslides, and incoherent landslides. The total morphoseismic features identified by this classification are 34 in number.« less

Detailed quantification of delta subsidence, compaction and interaction with man-made structures: the case of the NCA airport, France

NASA Astrophysics Data System (ADS)

Cavalié, O.; Sladen, A.; Kelner, M.

2015-06-01

River deltas are dynamic costal systems and their evolutions are closely monitored as it often concentrates vital natural resources for the surrounding areas. Many deltas, worldwide, experience subsidence due to geological processes (sediment loading and compaction) or human activities (groundwater or hydrocarbon extraction, land reclamation). This causes shoreline erosion or wetland loss which represent serious issues for the population. In this study, we investigate the dynamic of the Var delta (France) where reclaimed lands over sea have been built to host the Nice côte d'Azur airport (NCA). Actually, the stability of this infrastructure is a permanent concern since, in 1979, a newly built extension of the runway platform collapsed in the sea, causing important damages. The project of land extension stopped, but the present airport platform is still located on reclaimed land. Factors that can trigger such catastrophic landslide are thought to be linked to the delta activity and the artificial airport platform load. We used, therefore, Envisat InSAR data to measure accurately the ground deformation of the area that includes the Var delta and NCA airport. Combining data from ascending and descending orbits, we estimated the east-west and vertical components of the deformation and obtained very accurate displacement rate (with a 1σ error of 0.25 mm yr-1). We found that nearly all the deformation is vertical and impacts the whole Var delta. The Var valley subsides at a very low rate (0.5-1 mm yr-1) but downstream the subsidence rate increases and a clear jump is observed at the transition with the reclaimed lands (1-2 mm yr-1). On average, the reclaimed lands subside at 3 mm yr-1. Since the subsidence rate increases in correlation with the sediment thickness, we interpret it as the compaction of the delta quaternary sedimentary wedge. In addition, three areas subsides faster (between 5 and 10 mm yr-1), with one calling for more attention as it is the largest and overlooks the steep Var canyon. The progressive increase of subsidence rates toward the sea also suggests that the underwater parts of the margins could subside at rates well above 10 mm yr-1.

Detailed quantification of delta subsidence, compaction and interaction with man-made structures: the case of the NCA airport, France

NASA Astrophysics Data System (ADS)

Cavalié, O.; Sladen, A.; Kelner, M.

2015-09-01

River deltas are dynamic coastal systems and their evolutions are closely monitored as it often concentrates vital natural resources for the surrounding areas. Many deltas worldwide experience subsidence due to geological processes (sediment loading and compaction) or human activities (groundwater or hydrocarbon extraction, land reclamation). This causes shoreline erosion or wetland loss which represent serious issues for the population. In this study we investigate the dynamic of the Var delta (France) where reclaimed lands over sea have been built to host the Nice côte d'Azur airport (NCA). Actually, the stability of this infrastructure is a permanent concern since, in 1979, a newly built extension of the runway platform collapsed in the sea, causing important damages. The project of land extension stopped, but the present airport platform is still located on reclaimed land. Factors that can trigger such catastrophic landslide are thought to be linked to the delta activity and the artificial airport platform load. We used, therefore, Envisat InSAR data to measure accurately the ground deformation of the area that includes the Var delta and NCA airport. Combining data from ascending and descending orbits, we estimated the east-west and vertical components of the deformation and obtained very accurate displacement rate (with a 1σ error of 0.25 mm yr-1). We found that nearly all the deformation is vertical and impacts the whole Var delta. The Var valley subsides at a very low rate (0.5-1 mm yr-1) but downstream the subsidence rate increases and a clear jump is observed at the transition with the reclaimed lands (1-2 mm yr-1). On average, the reclaimed lands subside at 3 mm yr-1. Since the subsidence rate increases in correlation with the sediment thickness, we interpret it as the compaction of the delta quaternary sedimentary wedge. In addition, three areas subside faster (between 5 and 10 mm yr-1), with one calling for more attention as it is the largest and overlooks the steep Var canyon. The progressive increase of subsidence rates toward the sea also suggests that the underwater parts of the margins could subside at rates well above 10 mm yr-1.

45 CFR 2525.20 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) William D. Ford Federal Direct Loans. (i) Direct Subsidized and Unsubsidized Stafford Loans. (ii) Direct Subsidized and Unsubsidized Ford Loans. (iii) Direct Consolidation Loans. (3) Federal Perkins Loans. (i...

How Physician Perspectives on E-Prescribing Evolve over Time

PubMed Central

Patel, Vaishali; Pfoh, Elizabeth R.; Kaushal, Rainu

2016-01-01

Summary Background Physicians are expending tremendous resources transitioning to new electronic health records (EHRs), with electronic prescribing as a key functionality of most systems. Physician dissatisfaction post-transition can be quite marked, especially initially. However, little is known about how physicians’ experiences using new EHRs for e-prescribing evolve over time. We previously published a qualitative case study about the early physician experience transitioning from an older to a newer, more robust EHR, in the outpatient setting, focusing on their perceptions of the electronic prescribing functionality. Objective Our current objective was to examine how perceptions about using the new HER evolved over time, again with a focus on electronic prescribing. Methods We interviewed thirteen internists at an academic medical center-affiliated ambulatory care clinic who transitioned to the new EHR two years prior. We used a grounded theory approach to analyze semi-structured interviews and generate key themes. Results We identified five themes: efficiency and usability, effects on safety, ongoing training requirements, customization, and competing priorities for the EHR. We found that for even experienced e-prescribers, achieving prior levels of perceived prescribing efficiency took nearly two years. Despite the fact that speed in performing prescribing-related tasks was highly important, most were still not utilizing system short cuts or customization features designed to maximize efficiency. Alert fatigue remained common. However, direct transmission of prescriptions to pharmacies was highly valued and its benefits generally outweighed the other features considered poorly designed for physician workflow. Conclusions Ensuring that physicians are able to do key prescribing tasks efficiently is critical to the perceived value of e-prescribing applications. However, successful transitions may take longer than expected and e-prescribing system features that do not support workflow or require constant upgrades may further prolong the process. Additionally, as system features continually evolve, physicians may need ongoing training and support to maintain efficiency. PMID:27786335

Satellite radar interferometry for monitoring subsidence induced by longwall mining activity using Radarsat-2, Sentinel-1 and ALOS-2 data

NASA Astrophysics Data System (ADS)

Ng, Alex Hay-Man; Ge, Linlin; Du, Zheyuan; Wang, Shuren; Ma, Chao

2017-09-01

This paper describes the simulation and real data analysis results from the recently launched SAR satellites, ALOS-2, Sentinel-1 and Radarsat-2 for the purpose of monitoring subsidence induced by longwall mining activity using satellite synthetic aperture radar interferometry (InSAR). Because of the enhancement of orbit control (pairs with shorter perpendicular baseline) from the new satellite SAR systems, the mine subsidence detection is now mainly constrained by the phase discontinuities due to large deformation and temporal decorrelation noise. This paper investigates the performance of the three satellite missions with different imaging modes for mapping longwall mine subsidence. The results show that the three satellites perform better than their predecessors. The simulation results show that the Sentinel-1A/B constellation is capable of mapping rapid mine subsidence, especially the Sentinel-1A/B constellation with stripmap (SM) mode. Unfortunately, the Sentinel-1A/B SM data are not available in most cases and hence real data analysis cannot be conducted in this study. Despite the Sentinel-1A/B SM data, the simulation and real data analysis suggest that ALOS-2 is best suited for mapping mine subsidence amongst the three missions. Although not investigated in this study, the X-band satellites TerraSAR-X and COSMO-SkyMed with short temporal baseline and high spatial resolution can be comparable with the performance of the Radarsat-2 and Sentinel-1 C-band data over the dry surface with sparse vegetation. The potential of the recently launched satellites (e.g. ALOS-2 and Sentinel-1A/B) for mapping longwall mine subsidence is expected to be better than the results of this study, if the data acquired from the ideal acquisition modes are available.

Understanding the tropical cloud feedback from an analysis of the circulation and stability regimes simulated from an upgraded multiscale modeling framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Kuan-Man; Cheng, Anning

As revealed from studies using conventional general circulation models (GCMs), the thermodynamic contribution to the tropical cloud feedback dominates the dynamic contribution, but these models have difficulty in simulating the subsidence regimes in the tropics. In this study, we analyze the tropical cloud feedback from a 2 K sea surface temperature (SST) perturbation experiment performed with a multiscale modeling framework (MMF). The MMF explicitly represents cloud processes using 2-D cloud-resolving models with an advanced higher-order turbulence closure in each atmospheric column of the host GCM. We sort the monthly mean cloud properties and cloud radiative effects according to circulation andmore » stability regimes. Here, we find that the regime-sorted dynamic changes dominate the thermodynamic changes in terms of the absolute magnitude. The dynamic changes in the weak subsidence regimes exhibit strong negative cloud feedback due to increases in shallow cumulus and deep clouds while those in strongly convective and moderate-to-strong subsidence regimes have opposite signs, resulting in a small contribution to cloud feedback. On the other hand, the thermodynamic changes are large due to decreases in stratocumulus clouds in the moderate-to-strong subsidence regimes with small opposite changes in the weak subsidence and strongly convective regimes, resulting in a relatively large contribution to positive cloud feedback. The dynamic and thermodynamic changes contribute equally to positive cloud feedback and are relatively insensitive to stability in the moderate-to-strong subsidence regimes. But they are sensitive to stability changes from the SST increase in convective and weak subsidence regimes. Lastly, these results have implications for interpreting cloud feedback mechanisms.« less

Understanding the tropical cloud feedback from an analysis of the circulation and stability regimes simulated from an upgraded multiscale modeling framework

DOE PAGES

Xu, Kuan-Man; Cheng, Anning

2016-11-15

As revealed from studies using conventional general circulation models (GCMs), the thermodynamic contribution to the tropical cloud feedback dominates the dynamic contribution, but these models have difficulty in simulating the subsidence regimes in the tropics. In this study, we analyze the tropical cloud feedback from a 2 K sea surface temperature (SST) perturbation experiment performed with a multiscale modeling framework (MMF). The MMF explicitly represents cloud processes using 2-D cloud-resolving models with an advanced higher-order turbulence closure in each atmospheric column of the host GCM. We sort the monthly mean cloud properties and cloud radiative effects according to circulation andmore » stability regimes. Here, we find that the regime-sorted dynamic changes dominate the thermodynamic changes in terms of the absolute magnitude. The dynamic changes in the weak subsidence regimes exhibit strong negative cloud feedback due to increases in shallow cumulus and deep clouds while those in strongly convective and moderate-to-strong subsidence regimes have opposite signs, resulting in a small contribution to cloud feedback. On the other hand, the thermodynamic changes are large due to decreases in stratocumulus clouds in the moderate-to-strong subsidence regimes with small opposite changes in the weak subsidence and strongly convective regimes, resulting in a relatively large contribution to positive cloud feedback. The dynamic and thermodynamic changes contribute equally to positive cloud feedback and are relatively insensitive to stability in the moderate-to-strong subsidence regimes. But they are sensitive to stability changes from the SST increase in convective and weak subsidence regimes. Lastly, these results have implications for interpreting cloud feedback mechanisms.« less

Neogene evolution of the North New Guinea basin, Papua New Guinea: New constraints from seismic and subsidence analysis and implications for hydrocarbon exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, A.B.; Pigott, J.D.

1990-06-01

The present-day North New Guinea basin is a Plio-Pleistocene successor basin that formed subsequent to accretion of the Finisterre volcanic arc to the Australian Plate. The Ramu, Sepik, and Piore infrabasins formed in a forearc setting relative to the continental Maramuni magmatic arc. The evolution of these infrabasins was strongly influenced by accretion of the composite Torricelli-Prince Alexander terrane to the Australian Plate. Regional reflection seismic data and tectonic subsidence-subsidence rate calculations for seven wells drilled in the North New Guinea basin reveal a complex history. The timing and magnitude of subsidence and changes in subsidence rates differ between eachmore » of the Miocene infrabasins. A diachronous middle to late Miocene unconformity generally truncates infrabasin sequences. The Nopan No. 1 in the Sepik basin, however, has a complete middle Miocene to Pleistocene sedimentary record. This well records late Miocene negative subsidence rates documenting that the Nopan anticline grew as erosion occurred elsewhere in the region. This circumstance suggests that the major, sequence-bounding unconformity results from regional uplift and deformation, rather than changes in global sea level. The Plio-Pleistocene evolution of the North New Guinea basin has two profound implications regarding hydrocarbon exploration. First, the late Pliocene structural inversion of parts of the basin hinders stratigraphic and facies correlation inferred from the present setting. The recognition of basin inversion is particularly important in the Piore basin for predicting the distribution of potential reservoir facies in the Miocene carbonates. Second, the subsidence data suggest that although potential source rocks may be thermally within the oil window, these rocks may not have had sufficient time to mature owing to their recent burial.« less

A modeling study of coastal inundation induced by storm surge, sea-level rise, and subsidence in the Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhaoqing; Wang, Taiping; Leung, Lai-Yung R.

The northern coasts of the Gulf of Mexico are highly vulnerable to the direct threats of climate change, such as hurricane-induced storm surge, and such risks can be potentially exacerbated by land subsidence and global sea level rise. This paper presents an application of a coastal storm surge model to study the coastal inundation process induced by tide and storm surge, and its response to the effects of land subsidence and sea level rise in the northern Gulf coast. An unstructured-grid Finite Volume Coastal Ocean Model was used to simulate tides and hurricane-induced storm surges in the Gulf of Mexico.more » Simulated distributions of co-amplitude and co-phase of semi-diurnal and diurnal tides are in good agreement with previous modeling studies. The storm surges induced by four historical hurricanes (Rita, Katrina, Ivan and Dolly) were simulated and compared to observed water levels at National Oceanic and Atmospheric Administration tide stations. Effects of coastal subsidence and future global sea level rise on coastal inundation in the Louisiana coast were evaluated using a parameter “change of inundation depth” through sensitivity simulations that were based on a projected future subsidence scenario and 1-m global sea level rise by the end of the century. Model results suggested that hurricane-induced storm surge height and coastal inundation could be exacerbated by future global sea level rise and subsidence, and that responses of storm surge and coastal inundation to the effects of sea level rise and subsidence are highly nonlinear and vary on temporal and spatial scales.« less

Why the sacramento delta area differs from other parts of the great valley: numerical modeling of thermal structure and thermal subsidence of forearc basins

USGS Publications Warehouse

Mikhailov, V.O.; Parsons, T.; Simpson, R.W.; Timoshkina, E.P.; Williams, C.

2007-01-01

Data on present-day heat flow, subsidence history, and paleotemperature for the Sacramento Delta region, California, have been employed to constrain a numerical model of tectonic subsidence and thermal evolution of forearc basins. The model assumes an oceanic basement with an initial thermal profile dependent on its age subjected to refrigeration caused by a subducting slab. Subsidence in the Sacramento Delta region appears to be close to that expected for a forearc basin underlain by normal oceanic lithosphere of age 150 Ma, demonstrating that effects from both the initial thermal profile and the subduction process are necessary and sufficient. Subsidence at the eastern and northern borders of the Sacramento Valley is considerably less, approximating subsidence expected from the dynamics of the subduction zone alone. These results, together with other geophysical data, show that Sacramento Delta lithosphere, being thinner and having undergone deeper subsidence, must differ from lithosphere of the transitional type under other parts of the Sacramento Valley. Thermal modeling allows evaluation of the rheological properties of the lithosphere. Strength diagrams based on our thermal model show that, even under relatively slow deformation (10−17 s−1), the upper part of the delta crystalline crust (down to 20–22 km) can fail in brittle fashion, which is in agreement with deeper earthquake occurrence. Hypocentral depths of earthquakes under the Sacramento Delta region extend to nearly 20 km, whereas, in the Coast Ranges to the west, depths are typically less than 12–15 km. The greater width of the seismogenic zone in this area raises the possibility that, for fault segments of comparable length, earthquakes of somewhat greater magnitude might occur than in the Coast Ranges to the west.

InSAR Detection and Field Evidence for Thermokarst after a Tundra Wildfire, Using ALOS-PALSAR

DOE PAGES

Iwahana, Go; Uchida, Masao; Liu, Lin; ...

2016-03-08

Thermokarst is the process of ground subsidence caused by either the thawing of ice-rich permafrost or the melting of massive ground ice. The consequences of permafrost degradation associated with thermokarst for surface ecology, landscape evolution, and hydrological processes have been of great scientific interest and social concern. Part of a tundra patch affected by wildfire in northern Alaska (27.5 km 2) was investigated here, using remote sensing and in situ surveys to quantify and understand permafrost thaw dynamics after surface disturbances. A two-pass differential InSAR technique using L-band ALOS-PALSAR has been shown capable of capturing thermokarst subsidence triggered by amore » tundra fire at a spatial resolution of tens of meters, with supporting evidence from field data and optical satellite images. We have introduced a calibration procedure, comparing burned and unburned areas for InSAR subsidence signals, to remove the noise due to seasonal surface movement. In the first year after the fire, an average subsidence rate of 6.2 cm/year (vertical) was measured. Subsidence in the burned area continued over the following two years, with decreased rates. The mean rate of subsidence observed in our interferograms (from 24 July 2008 to 14 September 2010) was 3.3 cm/year, a value comparable to that estimated from field surveys at two plots on average (2.2 cm/year) for the six years after the fire. These results suggest that this InSAR-measured ground subsidence is caused by the development of thermokarst, a thawing process supported by surface change observations from high-resolution optical images and in situ ground level surveys.« less

Understanding Mississippi Delta Subsidence through Stratigraphic and Geotechnical Analysis of a Continuous Holocene Core at a Subsidence Superstation

NASA Astrophysics Data System (ADS)

Bridgeman, J.; Tornqvist, T. E.; Jafari, N.; Allison, M. A.

2017-12-01

Land-surface subsidence can be a major contributor to the relative sea-level rise that is threatening coastal communities. Loosely constrained subsidence rate estimates across the Mississippi Delta make it difficult to differentiate between subsidence mechanisms and complicate modeling efforts. New data from a nearly 40 m long, 12 cm diameter core taken during the installation of a subsidence monitoring superstation near the Mississippi River, SW of New Orleans, provides insight into the stratigraphic and geotechnical properties of the Holocene succession. Stratigraphically, the core can be grouped into three sections. The top 12 m is dominated by clastic overbank sediment with interspersed organic-rich layers. The middle section, 12-35 m consists predominately of mud, and the bottom section, 35-38.7 m, is marked by a transition into a Holocene-aged basal peat (11,350-11,190 cal BP) which overlies densely packed Pleistocene sediment. Radiocarbon and OSL ages show up to 6 m of vertical displacement since 3,000 cal BP. We infer that most of this was due to compaction of the thick underlying mud package. The top ­­­­­ 70 cm of the core is a peat that represents the modern marsh surface and is inducing minimal surface loading. This is consistent with the negligible shallow subsidence rate as seen at a nearby rod-surface elevation table - marker horizon station and the initial strainmeter data. Future compaction scenarios for the superstation can be modeled from the stratigraphic and geotechnical properties of the core, including the loading from the planned Mid-Barataria sediment diversion which is expected to dramatically change the coastal landscape in this region.

Estimating the Impact of Urban Expansion on Land Subsidence Using Time Series of DMSP Night-Time Light Satellite Imagery

NASA Astrophysics Data System (ADS)

Jiao, S.; Yu, J.; Wang, Y.; Zhu, L.; Zhou, Q.

2018-04-01

In recent decades, urbanization has resulted a massive increase in the amount of infrastructure especially large buildings in large cities worldwide. There has been a noticeable expansion of entire cities both horizontally and vertically. One of the common consequences of urban expansion is the increase of ground loads, which may trigger land subsidence and can be a potential threat of public safety. Monitoring trends of urban expansion and land subsidence using remote sensing technology is needed to ensure safety along with urban planning and development. The Defense Meteorological Satellite Program Operational Line scan System (DMSP/OLS) Night-Time Light (NTL) images have been used to study urbanization at a regional scale, proving the capability of recognizing urban expansion patterns. In the current study, a normalized illuminated urban area dome volume (IUADV) based on inter-calibrated DMSP/OLS NTL images is shown as a practical approach for estimating urban expansion of Beijing at a single period in time and over subsequent years. To estimate the impact of urban expansion on land subsidence, IUADV was correlated with land subsidence rates obtained using the Stanford Method for Persistent Scatterers (StaMPS) approach within the Persistent Scatterers InSAR (PSInSAR) methodology. Moderate correlations are observed between the urban expansion based on the DMSP/OLS NTL images and land subsidence. The correlation coefficients between the urban expansion of each year and land subsidence tends to gradually decrease over time (Coefficient of determination R = 0.80 - 0.64 from year 2005 to year 2010), while the urban expansion of two sequential years exhibit an opposite trend (R = 0.29 - 0.57 from year 2005 to year 2010) except for the two sequential years between 2007 and 2008 (R = 0.14).

U.S. Geological Survey Subsidence Interest Group Conference; proceedings of the Technical Meeting, Las Vegas, Nevada, February 14-16, 1995

USGS Publications Warehouse

Prince, Keith R.; Leake, Stanley A.

1997-01-01

Introducation to Papers: This report is a compilation of short papers that are based on oral presentations summarizing the results of recent research that were given at the third meeting of the Subsidence Interest Group held in Las Vegas, Nevada, February 14?16, 1995. The report includes case studies of land subsidence and aquifer-system deformation resulting from fluid withdrawal, geothermal development, and mine collapse. Methods for monitoring land subsidence using Global Positioning System technology for the rapid and accurate measurement of changes in land-surface altitude also are described. The current status of numerical simulation of land subsidence in the USGS is summarized, and several of the short papers deal with the development and application of new numerical techniques for simulation and quantification of aquifersystem deformation. Not all oral presentations made at the meeting are documented in this report. Several of the presentations were of ongoing research and as such, the findings were provisional in nature and were offered at the meeting to stimulate scientific discussion and debate among colleagues. The information presented in this report, although only a subset of the proceedings of the meeting in Las Vegas, should help expand the scientific basis for management decisions to mitigate or control the effects of land subsidence. The short papers describing the results of these studies provide a cross section of ongoing research in aquifer mechanics and land subsidence and also form an assessment of the current technology and 'state of the science.' The analytical and interpretive methods described in this report will be useful to scientists involved in studies of ground-water hydraulics and aquifer-system deformation.

Long Term Monitoring of Ground Motions in Upper Silesia Coal Basin (USCB) Using Satellite Radar Interferometry

NASA Astrophysics Data System (ADS)

Graniczny, Marek; Przylucka, Maria; Kowalski, Zbigniew

2016-08-01

Subsidence hazard and risk within the USCB are usually connected with the deep coal mining. In such cases, the surface becomes pitted with numerous collapse cavities or basins which depth may even reach tens of meters. The subsidence is particularly dangerous because of causing severe damage to gas and water pipelines, electric cables, and to sewage disposal systems. The PGI has performed various analysis of InSAR data in this area, including all three SAR bands (X, C and L) processed by DInSAR, PSInSAR and SqueeSAR techniques. These analyses of both conventional and advanced DInSAR approaches have proven to be effective to detect the extent and the magnitude of mining subsidence impact on urban areas. In this study an analysis of two series of subsequent differential interferograms obtained in the DInSAR technique are presented. SAR scenes are covering two periods and were acquired by two different satellites: ALOS-P ALSAR data from 22/02/2007- 27/05/2008 and TerraSAR-X data from 05/07/2011-21/06/2012. The analysis included determination of the direction and development of subsidence movement in relation to the mining front and statistic comparison between range and value of maximum subsidence detected for each mining area. Detailed studies were performed for Bobrek-Centrum mining area. They included comparison of mining fronts and location of the extracted coal seams with the observed subsidence on ALOS-P ALSAR InSAR interferograms. The data can help in estimation not only the range of the subsidence events, but also its value, direction of changes and character of the motion.

Why do adults entitled to free or highly subsidized dental services select fully out-of-pocket-paid care?

PubMed

Bayat, Fariborz; Vehkalahti, Miira M; Murtomaa, Heikki; Tala, Heikki

2010-02-01

To investigate patients' reasons for selecting a dental clinic given their choice of free or highly-subsidized dental services. The study was based on cross-sectional data obtained through phone interviews with adults in Tehran, Iran. The present study included those entitled to free or highly-subsidized dental services (n = 726). The data covered the patients' awareness of subsidized dental services and type of dental clinic for their most recent visit and their reasons for selecting that clinic. Awareness of subsidized dental services was dichotomized as being either aware or unaware of such subsidy. The type of clinic was dichotomized as providing either free or highly-subsidized (FHS) or fully out-of-pocket paid (FOP) services. Free format answers about the subjects' reasons for selecting a particular clinic were later sub-grouped as: convenient access, good technical aspects, good interpersonal aspects, low or reasonable fees, recommendation by a friend, and no reason. Socio-demographic status was based on background. Data analysis included the chi-square test and logistic regression model. Of the subjects (n = 726), 60% were women and 58% were under 35 years of age. The subjects' mean age was 33.5 years with no difference by gender (P = 0.24) and the majority had public insurance (91%). Of all the subjects, 60% selected FOP. Good interpersonal aspects were the strongest reason for selecting FOP (OR = 4.6), follow by good technical aspects (OR = 2.3). Those subjects who were unaware of their benefit had 4.6 times the odds of selecting FOP. Despite the opportunity to use highly-subsidized dental services, good interpersonal and good technical aspects lead patients to select private dentists and to pay fully out of pocket.

Knowledge extraction from evolving spiking neural networks with rank order population coding.

PubMed

Soltic, Snjezana; Kasabov, Nikola

2010-12-01

This paper demonstrates how knowledge can be extracted from evolving spiking neural networks with rank order population coding. Knowledge discovery is a very important feature of intelligent systems. Yet, a disproportionally small amount of research is centered on the issue of knowledge extraction from spiking neural networks which are considered to be the third generation of artificial neural networks. The lack of knowledge representation compatibility is becoming a major detriment to end users of these networks. We show that a high-level knowledge can be obtained from evolving spiking neural networks. More specifically, we propose a method for fuzzy rule extraction from an evolving spiking network with rank order population coding. The proposed method was used for knowledge discovery on two benchmark taste recognition problems where the knowledge learnt by an evolving spiking neural network was extracted in the form of zero-order Takagi-Sugeno fuzzy IF-THEN rules.

Detection of Old Mine Tunnels in Mexico City Highlands by Electric Resistivity Image Methods

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Tejero, A.; Cifuentes-Nava, G.; HernaNdez-Quintero, J.

2013-12-01

Electrical Resistivity Tomography (ERT) methods have been applied to study cavities or subsurface subsidence threatening urbanized areas. Unfortunately, ERT-3D techniques carried out on heavily urbanized areas become a difficult task, since parallel ERT arrays cannot be deployed. Then, a conventional regular grid cannot be carried out. We present a subsidence problem located in a densely populated portion of Mexico City highlands. Since the damaged houses are in the middle of a highly populated low-class neighborhood, an unconventional ERT array had to be applied. At first, a ';T'-array formed by two perpendicular transects was applied, deployed within a small alley, that stretched from the house entrance. This study determined a tubular structure beneath the houses following an irregular path at depth. Finally, houses were demolished due to the extensive damaged in their foundations. This made possible to carry out a second ERT-3D study, which included a dipolar array called ';L' and ';Corner' arrays. Such a new work defined a similar tubular structure. The cavity entrance was discovered, when excavations were made, although its precise shape could not be defined. The ERT-3D interpretation contributed to locate and accurately determine the geometrical characteristics of the geological feature that caused the collapse of dwellings.

MODFLOW-2000 Ground-Water Model--User Guide to the Subsidence and Aquifer-System Compaction (SUB) Package

DTIC Science & Technology

2003-01-01

compaction and water -level changes (Epstein, 1987 ; Hanson, 1989). More recent efforts have focused on incorporating subsidence calculations in widely...Horizontal aquifer movement in a Theis-Thiem confined system: Water Resources Research, v. 30, no. 4, p. 953–964. Heywood, C.E., 1997, Piezometric ...U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY MODFLOW-2000 Ground- Water Model—User Guide to the Subsidence and Aquifer-System Compaction

Detection of sinkhole precursors along the Dead Sea, Israel by SAR interferometry

NASA Astrophysics Data System (ADS)

Nof, Ran; Baer, Gidon; Ziv, Alon; Eyal, Yehuda; Raz, Eli; Atzori, Simone; Salvi, Stefano

2013-04-01

The water level of the Dead Sea (Israel and Jordan) has been dropping at an increasing rate since the 1960s, exceeding a meter per year during the last decade. This water-level drop has triggered the formation of sinkholes and widespread land subsidence along the Dead Sea shorelines, resulting in severe economic loss and infrastructural damage. In this study, sinkhole-related precursory subsidence and the effects of human activities on sinkhole development are examined through Interferometric Synthetic Aperture Radar (InSAR) measurements and field surveys conducted in Israel during the year 2012. Interferograms were generated using the COSMO-SkyMed satellite images and a high-resolution (0.5 m/pixel) elevation model that was obtained from airborne Light Detection and Ranging (LiDAR). Thanks to this unique integration of high-resolution datasets, mm-scale subsidence may be resolved in both undisturbed and human-disturbed environments. A few months long precursory subsidence occurred in all three sinkhole sites reported in this study. The centers of the subsiding areas and successive sinkholes in a specific site show lateral migration, possibly due to progressive dissolution and widening of the underlying cavities. Certain human activities, such as filling of newly formed sinkholes by gravel, or mud injections into nearby drill holes, seem to enhance land subsidence, widen existing sinkholes or even generate new sinkholes.

Research of land resources comprehensive utilization of coal mining in plain area based on GIS: case of Panyi Coal Mine of Huainan Mining Group Corp.

NASA Astrophysics Data System (ADS)

Dai, Chunxiao; Wang, Songhui; Sun, Dian; Chen, Dong

2007-06-01

The result of land use in coalfield is important to sustainable development in resourceful city. For surface morphology being changed by subsidence, the mining subsidence becomes the main problem to land use with the negative influence of ecological environment, production and steadily develop in coal mining areas. Taking Panyi Coal Mine of Huainan Mining Group Corp as an example, this paper predicted and simulated the mining subsidence in Matlab environment on the basis of the probability integral method. The change of land use types of early term, medium term and long term was analyzed in accordance with the results of mining subsidence prediction with GIS as a spatial data management and spatial analysis tool. The result of analysis showed that 80% area in Panyi Coal Mine be affected by mining subsidence and 52km2 perennial waterlogged area was gradually formed. The farmland ecosystem was gradually turned into wetland ecosystem in most study area. According to the economic and social development and natural conditions of mining area, calculating the ecological environment, production and people's livelihood, this paper supplied the plan for comprehensive utilization of land resource. In this plan, intervention measures be taken during the coal mining and the mining subsidence formation and development, and this method can solve the problems of Land use at the relative low cost.

Detecting and monitoring UCG subsidence with InSAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mellors, R J; Foxall, W; Yang, X

2012-03-23

The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidencemore » related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool to image UCG related subsidence. Data from newer satellites and improved algorithms will improve effectiveness.« less

A Generic multi-dimensional feature extraction method using multiobjective genetic programming.

PubMed

Zhang, Yang; Rockett, Peter I

2009-01-01

In this paper, we present a generic feature extraction method for pattern classification using multiobjective genetic programming. This not only evolves the (near-)optimal set of mappings from a pattern space to a multi-dimensional decision space, but also simultaneously optimizes the dimensionality of that decision space. The presented framework evolves vector-to-vector feature extractors that maximize class separability. We demonstrate the efficacy of our approach by making statistically-founded comparisons with a wide variety of established classifier paradigms over a range of datasets and find that for most of the pairwise comparisons, our evolutionary method delivers statistically smaller misclassification errors. At very worst, our method displays no statistical difference in a few pairwise comparisons with established classifier/dataset combinations; crucially, none of the misclassification results produced by our method is worse than any comparator classifier. Although principally focused on feature extraction, feature selection is also performed as an implicit side effect; we show that both feature extraction and selection are important to the success of our technique. The presented method has the practical consequence of obviating the need to exhaustively evaluate a large family of conventional classifiers when faced with a new pattern recognition problem in order to attain a good classification accuracy.

Study of stress-strain state of pipeline under permafrost conditions

NASA Astrophysics Data System (ADS)

Tarasenko, A. A.; Redutinskiy, M. N.; Chepur, P. V.; Gruchenkova, A. A.

2018-05-01

In this paper, the dependences of the stress-strain state and subsidence of pipelines on the dimensions of the subsidence zone are obtained for the sizes of pipes that have become most widespread during the construction of main oil pipelines (530x10, 820x12, 1020x12, 1020x14, 1020x16, 1220x14, 1220x16, 1220x18 mm). True values of stresses in the pipeline wall, as well as the exact location of maximum stresses for the interval of subsidence zones from 5 to 60 meters, are determined. For this purpose, the authors developed a finite element model of the pipeline that takes into account the actual interaction of the pipeline with the subgrade and allows calculating the SSS of the structure for a variable subsidence zone. Based on the obtained dependences for the underground laying of oil pipelines in permafrost areas, it is proposed to artificially limit the zone of possible subsidence by separation supports from the soil with higher building properties and physical-mechanical parameters. This technical solution would significantly reduce costs when constructing new oil pipelines in permafrost areas.

Microfossil measures of rapid sea-level rise: Timing of response of two microfossil groups to a sudden tidal-flooding experiment in Cascadia

USGS Publications Warehouse

Horton, B.P.; Milker, Yvonne; Dura, T.; Wang, Kelin; Bridgeland, W.T.; Brophy, Laura S.; Ewald, M.; Khan, Nicole; Engelhart, S.E.; Nelson, Alan R.; Witter, Robert C.

2017-01-01

Comparisons of pre-earthquake and post-earthquake microfossils in tidal sequences are accurate means to measure coastal subsidence during past subduction earthquakes, but the amount of subsidence is uncertain, because the response times of fossil taxa to coseismic relative sea-level (RSL) rise are unknown. We measured the response of diatoms and foraminifera to restoration of a salt marsh in southern Oregon, USA. Tidal flooding following dike removal caused an RSL rise of ∼1 m, as might occur by coseismic subsidence during momentum magnitude (Mw) 8.1–8.8 earthquakes on this section of the Cascadia subduction zone. Less than two weeks after dike removal, diatoms colonized low marsh and tidal flats in large numbers, showing that they can record seismically induced subsidence soon after earthquakes. In contrast, low-marsh foraminifera took at least 11 months to appear in sizeable numbers. Where subsidence measured with diatoms and foraminifera differs, their different response times may provide an estimate of postseismic vertical deformation in the months following past megathrust earthquakes.

Research on critical groundwater level under the threshold value of land subsidence in the typical region of Beijing

NASA Astrophysics Data System (ADS)

Jiang, Y.; Liu, J.-R.; Luo, Y.; Yang, Y.; Tian, F.; Lei, K.-C.

2015-11-01

Groundwater in Beijing has been excessively exploited in a long time, causing the groundwater level continued to declining and land subsidence areas expanding, which restrained the economic and social sustainable development. Long years of study show good time-space corresponding relationship between groundwater level and land subsidence. To providing scientific basis for the following land subsidence prevention and treatment, quantitative research between groundwater level and settlement is necessary. Multi-linear regression models are set up by long series factual monitoring data about layered water table and settlement in the Tianzhu monitoring station. The results show that: layered settlement is closely related to water table, water level variation and amplitude, especially the water table. Finally, according to the threshold value in the land subsidence prevention and control plan of China (45, 30, 25 mm), the minimum allowable layered water level in this region while settlement achieving the threshold value is calculated between -18.448 and -10.082 m. The results provide a reasonable and operable control target of groundwater level for rational adjustment of groundwater exploited horizon in the future.

Contributions of a Strengthened Early Holocene Monsoon and Sediment Loading to Present-Day Subsidence of the Ganges-Brahmaputra Delta

NASA Astrophysics Data System (ADS)

Karpytchev, M.; Ballu, V.; Krien, Y.; Becker, M.; Goodbred, S.; Spada, G.; Calmant, S.; Shum, C. K.; Khan, Z.

2018-02-01

The contribution of subsidence to relative sea level rise in the Ganges-Brahmaputra delta (GBD) is largely unknown and may considerably enhance exposure of the Bengal Basin populations to sea level rise and storm surges. This paper focuses on estimating the present-day subsidence induced by Holocene sediment in the Bengal Basin and by oceanic loading due to eustatic sea level rise over the past 18 kyr. Using a viscoelastic Earth model and sediment deposition history based on in situ measurements, results suggest that massive sediment influx initiated in the early Holocene under a strengthened South Asian monsoon may have contributed significantly to the present-day subsidence of the GBD. We estimate that the Holocene loading generates up to 1.6 mm/yr of the present-day subsidence along the GBD coast, depending on the rheological model of the Earth. This rate is close to the twentieth century global mean sea level rise (1.1-1.7 mm/yr). Thus, past climate change, by way of enhanced sedimentation, is impacting vulnerability of the GBD populations.

Integrated simulation of consumptive use and land subsidence in the Central Valley, California, for the past and for a future subject to urbanization and climate change

USGS Publications Warehouse

Hanson, Randall T.; Flint, Alan L.; Faunt, Claudia C.; Cayan, Daniel R.; Flint, Lorraine E.; Leake, Stanley A.; Schmid, Wolfgang

2010-01-01

Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States is consumed for agriculture and urban water supply. Continued agricultural use coupled with urban growth and potential climate change would result in continued depletion of groundwater storage and associated land subsidence throughout the Central Valley. For 1962-2003, an estimated 1,230 hectare meters (hm3) of water was withdrawn from fine-grained beds, resulting in more than three meters (m) of additional land subsidence locally. Linked physically-based, supply-constrained and emanddriven hydrologic models were used to simulate future hydrologic conditions under the A2 climate projection scenario that assumes continued "business as usual" greenhouse gas emissions. Results indicate an increased subsidence in the second half of the twenty-first century. Potential simulated land subsidence extends into urban areas and the eastern side of the valley where future surface-water deliveries may be depleted. 

Lost Hills Subsidence Animation

NASA Image and Video Library

2012-02-06

This frame from an animation depicts ground subsidence resulting from the extraction of oil. The oil fields are located near the community of Lost Hills, California, approximately 100 km northwest of Bakersfield.

Study on the Rule of Super Strata Movement and Subsidence

NASA Astrophysics Data System (ADS)

Yao, Shunli; Yuan, Hongyong; Jiang, Fuxing; Chen, Tao; Wu, Peng

2018-01-01

The movement of key strata is related to the safety of the whole earth’s surface for coal mining under super strata. Based on the key strata theory, the paper comprehensively analyzes the characteristics of the subsidence before and after the instability of the super strata by studing through FLAC3D and microseismic dynamic monitoring of the surface rock movement observation. The stability of the super strata movement is analyzed according to the characteristic value of the subsidence. The subsidence law and quantitative indexes under the control of the super rock strata that provides basis for the prevention and control of surface risk, optimize mining area and face layout and reasonably set mining boundary around mining area. It provides basis for the even growth of mine safety production and regional public safety.

Subsidence related to groundwater pumping for breweries in Merchtem area (Belgium), highlighted by Persistent Scaterrer Interferometry

NASA Astrophysics Data System (ADS)

Declercq, Pierre-Yves; Gerard, Pierre; Pirard, Eric; Perissin, Daniele; Walstra, Jan; Devleeschouwer, Xavier

2017-12-01

ERS, ENVISAT and TerraSAR-X Synthetic Aperture Radar scenes covering the time span 1992-2014 were processed using a Persistent Scatterer technique to study the ground movements in Merchtem (25 km NW of Brussels, Belgium). The processed datasets, covering three consecutive time intervals, reveal that the investigated area is affected by a global subsidence trend related to the extraction of groundwater in the deeper Cambro-Silurian aquifer. Through time the subsidence pattern is reduced and replaced by an uplift related to the rising water table attested by piezometers located in this aquifer. The subsidence is finally reduced to a zone where currently three breweries are very active and pump groundwater in the Ledo-Paniselian aquifer and in the Cambro-Silurian for process water for the production.

Major subsidence of the south-central United States of America and future inundation of coastal areas

NASA Astrophysics Data System (ADS)

Dokka, R. K.

2004-12-01

The northern shore of the Gulf of Mexico is the site of America's greatest wetland, the gateway to vast energy resources, and home to over 10 million people. This critical area is being increasingly threatened by progressive inundation by the relative rise of the Gulf of Mexico. This slow inundation was detected several decades ago and has been generally attributed to eustatic sea level rise, sediment starvation of the delta due to construction of flood control levees along the Mississippi River, and subsidence of the land relative to sea level. Although the former two effects are reasonably well understood, the lack of precise quantitative spatial data on the later related to a well defined, common datum has prevented the development of a satisfactory theory to explain modern surface motions. Analysis of National Geodetic Survey (NGS) 1st order leveling data produced vertical velocities for over 2700 benchmarks in Louisiana, Mississippi, Alabama, Texas, Arkansas, Florida, and Tennessee. All motions were related to NAVD88 and show that subsidence is not limited to coastal wetland areas, but rather includes the entire coastal zone as well as inland areas several hundred km from the shore. Subsidence can also be tracked to the north and follows the trend of the alluvial valley of the Mississippi River. Regionally, vertical velocities range from less than -30 mm/yr along the coast to over +5 mm/yr in peripheral areas of eastern Mississippi-Alabama. The mean rate is ~11 mm/yr in most coastal parishes of Louisiana. In the Mississippi River deltaic plain, subsidence was significantly higher than previous estimates based on long-term geologic measurements. The data also indicate that adjacent alluvial ridges where the population is concentrated have been similarly affected. In the Chenier plain of southwest Louisiana, a region previously thought to be subsiding at slowly, rates of sinking are similar to those of the deltaic plain. Demonstration that all areas of the coastal landscape as well as inland areas are affected implies that subsidence recorded by benchmarks is not solely due to local sedimentary processes and/or the activities of humans. Instead, geodetic data when integrated with subsurface geologic information suggest that subsidence includes a strong regional component that is the product of lithospheric flexure and normal faulting. This component is mainly due to the derivative effects of late Quaternary sediment loads such as the modern Mississippi River delta and Pleistocene deposits offshore. Models of simple flexure are inadequate, however, to explain the regional component of subsidence. Instead, it is proposed that active faulting plays a key role in regional subsidence throughout the coast by episodically weakening the lithosphere, which in turn changes the way that the lithosphere bears the load of sediments over time. Salt intrusion/evacuation induced by loading is a major cause of subsidence in southwest Louisiana. If subsidence continues at similar rates and construction efforts fail to build protection levees to appropriate heights, substantial portions of the gulf coast (primarily Louisiana) will lie below sea level and be inundated by end of this century. In Louisiana, this will result in a loss of ~$140B of land and property, as well as the land, livelihoods, and cultural heritage of over 2 million people.

Belief Revision in Children: The Role of Prior Knowledge and Strategies for Generating Evidence.

ERIC Educational Resources Information Center

Schauble, Leona

1990-01-01

Evolving beliefs and reasoning strategies of 22 fifth and sixth graders working on a causal reasoning problem were observed. Children conducted experiments to learn about relations between design features and speed of race cars in a computerized "microworld." Subjects did not attain full understanding of features disconfirming their…

Learning Spatio-Temporal Representations for Action Recognition: A Genetic Programming Approach.

PubMed

Liu, Li; Shao, Ling; Li, Xuelong; Lu, Ke

2016-01-01

Extracting discriminative and robust features from video sequences is the first and most critical step in human action recognition. In this paper, instead of using handcrafted features, we automatically learn spatio-temporal motion features for action recognition. This is achieved via an evolutionary method, i.e., genetic programming (GP), which evolves the motion feature descriptor on a population of primitive 3D operators (e.g., 3D-Gabor and wavelet). In this way, the scale and shift invariant features can be effectively extracted from both color and optical flow sequences. We intend to learn data adaptive descriptors for different datasets with multiple layers, which makes fully use of the knowledge to mimic the physical structure of the human visual cortex for action recognition and simultaneously reduce the GP searching space to effectively accelerate the convergence of optimal solutions. In our evolutionary architecture, the average cross-validation classification error, which is calculated by an support-vector-machine classifier on the training set, is adopted as the evaluation criterion for the GP fitness function. After the entire evolution procedure finishes, the best-so-far solution selected by GP is regarded as the (near-)optimal action descriptor obtained. The GP-evolving feature extraction method is evaluated on four popular action datasets, namely KTH, HMDB51, UCF YouTube, and Hollywood2. Experimental results show that our method significantly outperforms other types of features, either hand-designed or machine-learned.

77 FR 2550 - Proposed Information Collection Activity; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-18

...-sufficiency. The projects will evaluate up to twelve subsidized and transitional employment programs... Number 0970-0384), a descriptive study of American Recovery and Reinvestment Act (ARRA)-funded subsidized...

On retrodictions of global mantle flow with assimilated surface velocities

NASA Astrophysics Data System (ADS)

Colli, Lorenzo; Bunge, Hans-Peter; Schuberth, Bernhard S. A.

2016-04-01

Modeling past states of Earth's mantle and relating them to geologic observations such as continental-scale uplift and subsidence is an effective method for testing mantle convection models. However, mantle convection is chaotic and two identical mantle models initialized with slightly different temperature fields diverge exponentially in time until they become uncorrelated, thus limiting retrodictions (i.e., reconstructions of past states of Earth's mantle obtained using present information) to the recent past. We show with 3-D spherical mantle convection models that retrodictions of mantle flow can be extended significantly if knowledge of the surface velocity field is available. Assimilating surface velocities produces in some cases negative Lyapunov times (i.e., e-folding times), implying that even a severely perturbed initial condition may evolve toward the reference state. A history of the surface velocity field for Earth can be obtained from past plate motion reconstructions for time periods of a mantle overturn, suggesting that mantle flow can be reconstructed over comparable times.

On retrodictions of global mantle flow with assimilated surface velocities

NASA Astrophysics Data System (ADS)

Colli, Lorenzo; Bunge, Hans-Peter; Schuberth, Bernhard S. A.

2015-10-01

Modeling past states of Earth's mantle and relating them to geologic observations such as continental-scale uplift and subsidence is an effective method for testing mantle convection models. However, mantle convection is chaotic and two identical mantle models initialized with slightly different temperature fields diverge exponentially in time until they become uncorrelated, thus limiting retrodictions (i.e., reconstructions of past states of Earth's mantle obtained using present information) to the recent past. We show with 3-D spherical mantle convection models that retrodictions of mantle flow can be extended significantly if knowledge of the surface velocity field is available. Assimilating surface velocities produces in some cases negative Lyapunov times (i.e., e-folding times), implying that even a severely perturbed initial condition may evolve toward the reference state. A history of the surface velocity field for Earth can be obtained from past plate motion reconstructions for time periods of a mantle overturn, suggesting that mantle flow can be reconstructed over comparable times.

E-Area Low-Level Waste Facility Vadose Zone Model: Confirmation of Water Mass Balance for Subsidence Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyer, J. A.

In preparation for the next revision of the E-Area Low-Level Waste Facility (LLWF) Performance Assessment (PA), a mass balance model was developed in Microsoft Excel to confirm correct implementation of intact- and subsided-area infiltration profiles for the proposed closure cap in the PORFLOW vadose-zone model. The infiltration profiles are based on the results of Hydrologic Evaluation of Landfill Performance (HELP) model simulations for both intact and subsided cases.

Is There a Tectonic Component On The Subsidence Process In Morelia, Mexico?

NASA Astrophysics Data System (ADS)

Cabral-Cano, E.; Arciniega-Ceballos, A.; Diaz-Molina, O.; Garduno-Monroy, V.; Avila-Olivera, J.; Hernández-Madrigal, V.; Hernández-Quintero, E.

2009-12-01

Subsidence and faulting have affected cities in central Mexico for decades. This process causes substantial damages to the urban infrastructure, housing and large buildings, and is an important factor to be consider when planning urban development, land use zoning and hazard mitigation strategies. In Mexico, studies using InSAR and GPS based observations have shown that high subsidence areas are usually associated with the presence of thick lacustrine and fluvial deposits. In most cases the subsidence is closely associated with intense groundwater extraction that results in sediment consolidation. However, recent studies in the colonial city of Morelia in central Mexico show a different scenario, where groundwater extraction cannot solely explain the observed surface deformation. Our results indicate that a more complex interplay between sediment consolidation and tectonic forces is responsible for the subsidence and fault distribution within the city. The city of Morelia has experienced fault development recognized since the 80’s. This situation has led to the recognition of 9 NE-SW trending faults that cover most of its urbanized area. Displacement maps derived from differential InSAR analysis show that the La Colina fault is the highest subsiding area in Morelia with maximum annual rates over -35 mm/yr. However, lithological mapping and field reconnaissance clearly show basalts outcropping this area of high surface deformation. The subsurface characterization of the La Colina fault was carried out along 27 Ground Penetrating Radar (GPR) sections and 6 seismic tomography profiles. Assuming a constant, linear past behavior of the subsidence as observed by InSAR techniques, and based on the interpretation of the fault dislocation imaged by the shallow GPR and seismic tomography, it is suggested that the La Colina fault may have been active for the past 220-340 years and clearly pre-dates the intense water well extraction from the past century. These conditions suggest the existence of a tectonic component overlapped to the soil consolidation and its related subsidence. Therefore, these results suggest that the fault system observed within the city of Morelia may be an active segment of the Morelia-Acambay tectonic fault system.

Warm-Core Intensification Through Horizontal Eddy Heat Transports into the Eye

NASA Technical Reports Server (NTRS)

Braun, Scott A.; Montgomery, Michael T.; Fulton, John; Nolan, David S.; Starr, David OC. (Technical Monitor)

2001-01-01

The mechanism for the formation and intensification of the hurricane warm core is not well understood. The generally accepted explanation is that the warm core forms as a result of gentle subsidence of air within the eye that warms as a result of adiabatic compression. Malkus suggested that this subsidence is part of a deep circulation in which air begins descent at high levels in the eye, acquires cyclonic angular momentum as it descends to lower levels, and then diverges at low levels, where it is entrained back into the eyewall. Inward mixing from the eyewall is hypothesized to force the subsidence and maintain the moisture and momentum budgets of the subsiding air. Willoughby suggested that air within the eye has remained so since it was first enclosed during the formation of the eyewall and that it subsides at most only a few kilometers rather than through the depth of the troposphere. He relates the subsidence to the low-level divergence and entrainment into the eyewall noted by Malkus, but suggests that shrinkage of the eye's volume is more than adequate to account for the air lost to the eyewall or converted to cloudy air by turbulent mixing across the eye boundary. Smith offered an alternative view of the subsidence forcing, suggesting that vertical motion in a mature hurricane eye is generated largely by imbalances between the downward vertical pressure gradient force and the upward buoyancy force. The vertical pressure gradient force is associated with the decay and/or radial spread of the tangential wind field with height at those levels were the winds are in approximate gradient wind balance. The rate of subsidence is just that required to warm the air sufficiently such that the buoyancy remains in close hydrostatic balance with an increasing vertical pressure gradient force. In this study, a very high-resolution simulation of Hurricane Bob using a cloud-resolving grid scale of 1.3 km is used to examine the heat budget within the storm with particular emphasis on the mechanisms for warming of the eye.

Variation of the subsidence parameters, effective thermal conductivity, and mantle dynamics

NASA Astrophysics Data System (ADS)

Adam, C.; King, S. D.; Vidal, V.; Rabinowicz, M.; Jalobeanu, A.; Yoshida, M.

2015-09-01

The subsidence of young seafloor is generally considered to be a passive phenomenon related to the conductive cooling of the lithosphere after its creation at mid-oceanic ridges. Recent alternative theories suggest that the mantle dynamics plays an important role in the structure and depth of the oceanic lithosphere. However, the link between mantle dynamics and seafloor subsidence has still to be quantitatively assessed. Here we provide a statistical study of the subsidence parameters (subsidence rate and ridge depth) for all the oceans. These parameters are retrieved through two independent methods, the positive outliers method, a classical method used in signal processing, and through the MiFil method. From the subsidence rate, we compute the effective thermal conductivity, keff, which ranges between 1 and 7 W m-1 K-1. We also model the mantle flow pattern from the S40RTS tomography model. The density anomalies derived from S40RTS are used to compute the instantaneous flow in a global 3D spherical geometry. We show that departures from the keff = 3 Wm-1K-1 standard value are systematically related to mantle processes and not to lithospheric structure. Regions characterized by keff > 3 Wm-1K-1 are associated with mantle uplifts (mantle plumes or other local anomalies). Regions characterized by keff < 3 Wm-1K-1 are related to large-scale mantle downwellings such as the Australia-Antarctic Discordance (AAD) or the return flow from the South Pacific Superswell to the East Pacific Rise. This demonstrates that mantle dynamics plays a major role in the shaping of the oceanic seafloor. In particular, the parameters generally considered to quantify the lithosphere structure, such as the thermal conductivity, are not only representative of this structure but also incorporate signals from the mantle convection occurring beneath the lithosphere. The dynamic topography computed from the S40RTS tomography model reproduces the subsidence pattern observed in the bathymetry. Overall we find a good correlation between the subsidence parameters derived from the bathymetry and the dynamic topography. This demonstrates that these parameters are strongly dependent on mantle dynamics.

Comparison of Subsidence Rates for Conjugate Margins of the Equatorial and Northern South Atlantic Ocean as A First-Order Constraint on Symmetry of Underlying, Early Rift Structures

NASA Astrophysics Data System (ADS)

Zavala, O.

2017-12-01

We compared subsidence histories from wells into Cretaceous-Cenozoic conjugate margins in the Equatorial and northern South Atlantic as a first-order constraint on whether rifting occurred in a symmetrical, pure shear mode, or whether rifting occurred in an asymmetrical, simple shear mode. For the pure shear mode of rifting, the prediction is for longterm subsidence on both conjugate margins to be similar and reflective of underlying, rift symmetry; for the simple shear mode of rifting, the prediction is that subsidence above the more thinned and wider, lower plate margin is greater than subsidence above the less thinned and more narrow, upper plate margin. A major caveat of this approach is that subsidence variations can be affected by other external factors that include increased sedimentation related to local deltas and structural or hotspot-related uplifts of coastal areas. In the northern Equatorial Atlantic, the longterm subsidence rate for the Guyana basin of northeastern South America of 18.52 m/Ma is less that of the Senegal area of west Africa of 54 m/Ma suggestive of an upper plate to the west and lower plate to the east. Moving southwards, the Potiguar basin of northern Brazil of 23 m/Ma is roughly the same as the Keta-Togo-Benin-Cote d'Ivoire basins of west Africa (21 m/Ma) and suggestive of an underlying rift symmetry. The Bahia Norte-Reconcavo-Sergipe-Alogoas basins of Brazil are less (28 m/Ma) than the Gabon basin (57 m/Ma) of west Africa suggesitive of an lower plate to the east and an upper plate to the west. The Bahia Sul-Espirito Santo basins of Brazil are less (20 m/Ma) than the Lower Congo basin (45 m/Ma) although the latter area includes the localized influence of the Congo delta. We compare additional evidence such as seismic reflection and refraction data and gravity modeling to the predictions of the subsidence values.

Production induced subsidence and seismicity in the Groningen gas field - can it be managed?

NASA Astrophysics Data System (ADS)

de Waal, J. A.; Muntendam-Bos, A. G.; Roest, J. P. A.

2015-11-01

Reliable prediction of the induced subsidence resulting from gas production is important for a near sea level country like the Netherlands. Without the protection of dunes, dikes and pumping, large parts of the country would be flooded. The predicted sea-level rise from global warming increases the challenge to design proper mitigation measures. Water management problems from gas production induced subsidence can be prevented if measures to counter its adverse effects are taken timely. This requires reliable subsidence predictions, which is a major challenge. Since the 1960's a number of large, multi-decade gas production projects were started in the Netherlands. Extensive, well-documented subsidence prediction and monitoring technologies were applied. Nevertheless predicted subsidence at the end of the Groningen field production period (for the centre of the bowl) went from 100 cm in 1971 to 77 cm in 1973 and then to 30 cm in 1977. In 1984 the prediction went up again to 65 cm, down to 36 cm in 1990 and then via 38 cm (1995) and 42 cm (2005) to 47 cm in 2010 and 49 cm in 2013. Such changes can have large implications for the planning of water management measures. Until 1991, when the first event was registered, production induced seismicity was not observed nor expected for the Groningen field. Thereafter the number of observed events rose from 5 to 10 per year during the 1990's to well over a hundred in 2013. The anticipated maximum likely magnitude rose from an initial value of less than 3.0 to a value of 3.3 in 1993 and then to 3.9 in 2006. The strongest tremor to date occurred near the village of Huizinge in August 2012. It had a magnitude of 3.6, caused significant damage and triggered the regulator into an independent investigation. Late 2012 it became clear that significantly larger magnitudes cannot be excluded and that values up to magnitude 5.0 cannot be ruled out. As a consequence the regulator advised early 2013 to lower Groningen gas production by as much and as fast as realistically possible. Before taking such a decision, the Minister of Economic Affairs requested further studies. The results became available early 2014 and led to the government decision to lower gas production in the earthquake prone central area of the field by 80 % for the next three~years. In addition further investigations and a program to strengthen houses and infrastructure were started. Important lessons have been learned from the studies carried out to date. It is now realised that uncertainties in predicted subsidence and seismicity are much larger than previously recognised. Compaction, subsidence and seismicity are strongly interlinked and relate in a non-linear way to production and pressure drop. The latest studies by the operator suggest that seismic hazard in Groningen is largely determined by tremors with magnitudes between 4.5 and 5.0 even at an annual probability of occurrence of less than 1 %. And that subsidence in 2080 in the centre of the bowl could be anywhere between 50 and 70 cm. Initial evaluations by the regulator indicate similar numbers and suggest that the present seismic risk is comparable to Dutch flooding risks. Different models and parameters can be used to describe the subsidence and seismicity observed so far. The choice of compaction and seismicity models and their parameters has a large impact on the calculated future subsidence (rates), seismic activity and on the predicted response to changes in gas production. In addition there are considerable uncertainties in the ground motions resulting from an earthquake of a given magnitude and in the expected response of buildings and infrastructure. As a result uncertainties in subsidence and seismicity become very large for periods more than three to five years into the future. To counter this a control loop based on interactive modelling, measurements and repeated calibration will be used. Over the coming years, the effect of the production reduction in the centre of the field on subsidence and seismicity will be studied in detail in an effort to improve understanding and thereby reduce prediction uncertainties. First indications are that the reduction has led to a drop in subsidence rate and seismicity within a period of a few months. This suggests that the system can be controlled and regulated. If this is the case, the integrated loop of predicting, monitoring and updating in combination with mitigation measures can be applied to keep subsidence (rate) and induced seismicity within limits. To be able to do so, the operator has extended the field-monitoring network. It now includes PS-InSAR and GPS stations for semi-permanent subsidence monitoring in addition to a traditional network of levelling benchmarks. For the seismic monitoring 60 shallow (200 m) borehole seismometers, 60 + accelerometers and two permanent downhole seismic arrays at reservoir level will be added. Scenario's spanning the range of parameter and model uncertainties will be generated to calculate possible subsidence and seismicity outcomes. The probability of each scenario will be updated over time through confrontation with the measurements as they become available. At regular intervals the subsidence prediction and the seismic risk will be re-evaluated. Further mitigation measures, possibly including further production measures will need to be taken if probabilities indicate unacceptable risks.

Declining growth of Mauna Loa during the last 100,000 years: Rates of lava accumulation vs. gravitational subsidence

NASA Astrophysics Data System (ADS)

Lipman, Peter W.

Long-term growth rates of Hawaiian volcanoes are difficult to determine because of the short historical record, problems in dating tholeiitic basalt by K-Ar methods, and concealment of lower volcanic flanks by 5 km of seawater. Combined geologic mapping, petrologic and geochemical studies, geochronologic determinations, marine studies, and scientific drilling have shown that, despite frequent large historical eruptions (avg. 1 per 7 years since mid 19th century), the lower subaerial flanks of Mauna Loa have grown little during the last hundred thousand years. Coastal lava-accumulation rates have averaged less than 2 mm/year since 10 to 100 ka along the Mauna Loa shoreline, slightly less than recent isostatic subsidence rates of 2.4-2.6 mm/yr. Since 30 ka, lava accumulation has been greatest on upper flanks of the volcano at times of summit caldera overflows; rift eruptions have been largely confined to vents at elevations above +2,500 m, and activity has diminished lower along both rift zones. Additional indicators of limited volcanic construction at lower levels and declining eruptive activity include: (1) extensive near-surface preservation of Pahala Ash along the southeast coast, dated as older than about 30 ka; (2) preservation in the Ninole Hills of block-slumped ancestral Mauna Loa lavas erupted at 100-200 ka; (3) preservation low in the subaerial Kealakekua landslide fault scarp of lavas newly dated by K-Ar as 166±53 ka; (4) preservation of submerged coral reefs (150 m depth) dated at 14 ka and fossil shoreline features (as much as 350-400 m depth), with estimated ages of 130-150 ka, that have survived without burial by younger Mauna Loa lavas and related ocean-entry debris; (5) incomplete filling of old landslide breakaway scars; (6) limited deposition of post-landslide lava on lower submarine slopes (accumulation mostly <1,000 m depth); and (7) decreased deformation and gravitational instability of the volcanic edifice. In addition, the estimated recent magma-supply rate for Mauna Loa, about 28×106 m3/yr since 4 ka (including intrusions), is inadequate to have constructed the present-day edifice (80×103 km3) within a geologically feasible interval (0.6-1.0 m.y.); higher magma supply (100×106 m3/yr?, comparable to present-day Kilauea) must have prevailed during earlier times of more rapid volcano growth. Interpreted collectively, these features indicate that the emerged area of Mauna Loa and its eruptive vigor were greater in the past than at present. Volcanic growth due to lava accumulation has been offset by subsidence and by landsliding on the lower Hanks of the volcano. Along with the apparent "drying up" of distal parts of the rift zones, these features suggest that Mauna Loa is nearing the end of the tholeiitic shield-building stage of Hawaiian volcanism.

Mantle wedge serpentinisation in a cold subduction setting: implications for slow-slip, subsidence, and large, negative, gravity anomalies

NASA Astrophysics Data System (ADS)

Stern, T. A.; Dimech, J.; Henrys, S.; Horgan, H. J.; Lamb, S. H.

2016-12-01

Seismic exploration of the crust in the behind-subduction region of New Zealand's southern Hikurangi margin provides new evidence for a link between serpentinization, megathrust slow slip events and large (-150 mgal) negative gravity anomalies. Our analysis focuses on a high resolution, crustal scale, migrated, seismic reflection data set collected with a 10-km-long streamer. A dominant feature of the data is a localized region of relatively bright reflectors, at a depth of 30 km where the overlying Australian plate Moho abuts the subducted Pacific plate. The reflectors are arched in a feature that resembles a hanging-wall anticline faulted. We interpret these features to image the top of a serpentinized mantle wedge, because: (1) a drop in the frequency content of reflections below the high amplitude reflectors indicates strong attenuation (Q 20±10) of seismic energy in the wedge; (2) there is a polarity/impedance contrast reversal implying a drop in seismic P-wave speed; and (3) large regions of Moho reflectivity adjacent to the bright reflectivity are weak or absent. We suggest that the mantle wedge in the southern portion of the Hikurangi margin is cold enough for peridotite to be hydrated and altered to antigorite, thereby giving rise to the observed seismic reflection characteristics and creating a lower viscosity mantle wedge. In the past 4 My, a roughly circular sedimentary basin, up to 4 km deep, has developed in the region, and this basin is associated with a -150 mgal free-air and Bouguer gravity anomaly. We propose that serpentinite is implicated in both the subsidence, due to induced pressure gradients as it undergoes corner flow above the subducted slab, and the strong negative gravity anomaly. Serpentinisation of 50% will lower the density of peridotite by about 300 kg/m3, and this could account for up to -100 mgal of the observed anomaly. Finally, the proximity of recently documented slow-slip events to the proposed zone of serpentinisation supports a causal link between the two phenomena.

On the use of InSAR technology to assess land subsidence in Jakarta coastal flood plain

NASA Astrophysics Data System (ADS)

Koudogbo, Fifame; Duro, Javier; Garcia Robles, Javier; Arnaud, Alain; Abidin, Hasanuddin Z.

2014-05-01

Jakarta is the capital of Indonesia and is home to approximately 10 million people on the coast of the Java Sea. It is situated on the northern coastal alluvial plane of Java which shares boundaries with West Java Province in the south and in the east, and with Banten Province in the west. The Capital District of Jakarta (DKI) sits in the lowest lying areas of the basin. Its topography varies, with the northern part just meters above current sea level and lying on a flood plain. Subsequently, this portion of the city frequently floods. The southern part of the city is hilly. Thirteen major rivers flow through Jakarta to the Java Sea. The Ciliwung River is the most significant river and divides the city West to East. In the last three decades, urban growing of Jakarta has been very fast in sectors as industry, trade, transportation, real estate, among others. This exponential development has caused several environmental issues; land subsidence is one of them. Subsidence in Jakarta has been known since the early part of the 20th century. It is mainly due to groundwater extraction, the fast development (construction load), soil natural consolidation and tectonics. Evidence of land subsidence exists through monitoring with GPS, level surveys and InSAR investigations. InSAR states for "Interferometric Synthetic Aperture Radar". Its principle is based on comparing the distance between the satellite and the ground in consecutive satellite passes over the same area on the Earth's surface. Radar satellites images record, with very high precision, the distance travelled by the radar signal that is emitted by the satellite is registered. When this distance is compared through time, InSAR technology can provide highly accurate ground deformation measurements. ALTAMIRA INFORMATION, company specialized in ground motion monitoring, has developed GlobalSARTM, which combines several processing techniques and algorithms based on InSAR technology, to achieve ground motion measurements with millimetric precision and high accuracy. World Bank studies conservatively estimate land subsidence in Jakarta occurring at an average rate of 5 cm per year, and in some areas, over 1 meters was already observed. Recent studies of land subsidence found that while typical subsidence rates were 7.5-10 cm a year, in localized areas of North Jakarta subsidence in the range 15-25 cm a year was occurring, which if sustained, would result in them sinking to 4 to 5 meters below sea level by 2025. Land subsidence will require major interventions, including increased pumping, dikes and most likely introducing major infrastructure investment for sea defense. With the increasing prevalence of Earth Observation, the World Bank and the European Space Agency have set up a partnership that aims at highlighting the potential of EO information to support the monitoring and management of World Bank projects. In this framework ALTAMIRA INFORMATION has assessed land subsidence in Jakarta. Impressive results have been obtained by providing high resolution measurements which can help in improving the characterization of the subsidence mechanisms.

Revised Thorium Abundances for Lunar Red Spots

NASA Technical Reports Server (NTRS)

Hagerty, J. J.; Lawrence, D. J.; Elphic, R. C.; Feldman, W. C.; Vaniman, D. T.; Hawke, B. R.

2005-01-01

Lunar red spots are features on the nearside of the Moon that are characterized by high albedo and by a strong absorption in the ultraviolet. These red spots include the Gruithuisen domes, the Mairan domes, Hansteen Alpha, the southern portion of Montes Riphaeus, Darney Chi and Tau, Helmet, and an area near the Lassell crater. It has been suggested that many of the red spots are extrusive, nonmare, volcanic features that could be composed of an evolved lithlogy enriched in thorium. In fact, Hawke et al. used morphological characteristics to show that Hansteen Alpha is a nonmare volcanic construct. However, because the apparent Th abundances (6 - 7 ppm) were lower than that expected for evolved rock types, Hawke et al. concluded that Hansteen Alpha was composed of an unknown rock type. Subsequent studies by Lawrence et al. used improved knowledge of the Th spatial distribution for small area features on the lunar surface to revisit the interpretation of Th abundances at the Hansteen Alpha red spot. As part of their study, Lawrence et al. used a forward modeling technique to show that the Th abundance at Hansteen Alpha is not 6 ppm, but is more likely closer to 25 ppm, a value consistent with evolved lithologies. This positive correlation between the morphology and composition of Hansteen Alpha provides support for the presence of evolved lithologies on the lunar surface. It is possible, however, that Hansteen Alpha represents an isolated occurrence of non-mare volcanism. That is why we have chosen to use the forward modeling technique of Lawrence et al. to investigate the Th abundances at other lunar red spots, starting with the Gruithuisen domes. Additional information is included in the original extended abstract.

Emplacement and magnetic fabrics of rapakivi granite intrusions within Wiborg and Åland rapakivi granite batholiths in Finland

NASA Astrophysics Data System (ADS)

Karell, Fredrik; Ehlers, Carl; Airo, Meri-Liisa

2014-02-01

Anisotropy of magnetic susceptibility (AMS) studies were carried out in two areas in Finland: the Ruotsinpyhtää intrusion within the Wiborg rapakivi granite batholith and the Saltvik intrusions within the Åland rapakivi granite batholith. The main aim of this study was to understand the emplacement history of these mid-Proterozoic rapakivi granites. Aeromagnetic images reveal structures of ca. 5-10 km intrusions that build up the large rapakivi granite batholiths of Åland and Wiborg. Magnetic susceptibility data from the database of the Geological Survey of Finland, including more than 1700 samples from the Wiborg rapakivi batholith and almost 900 samples from the Åland rapakivi batholith, were compared with measurements from the present study. The mean susceptibility is ca. 1500 μSI for the Wiborg batholith and ca. 10,000 μSI for the Åland batholith. Samples taken for this study demonstrate that the mean value for the Ruotsinpyhtää intrusion is ca. 1200 μSI and for the Saltvik intrusions ca. 24,000 μSI. Thermomagnetic measurements reveal that the magnetic susceptibility is mainly derived either from paramagnetic minerals or from magnetite. The absence of solid-state deformation features such as breccia or contact deformation indicates a cauldron-type subsidence emplacement. The AMS measurements from Ruotsinpyhtää confirm these proposals, with concentric gently dipping magnetic foliations that support a ring complex structure above a piston-type subsidence system. The Saltvik area consists of a number of smaller elliptical intrusions of different rapakivi granites forming a multiple intrusive complex. The magnetic fabric shows a general westward dipping of the pyterlite and eastward dipping of the contiguous even-grained rapakivi granite, which indicates a central inflow of magma batches towards the east and west resulting from a laccolitic emplacement of magma batches, while the main mechanism for space creation was derived from subsidence.

Unconventional maar diatreme and associated intrusions in the soft sediment-hosted Mardoux structure (Gergovie, France)

NASA Astrophysics Data System (ADS)

Valentine, Greg A.; van Wyk de Vries, Benjamin

2014-03-01

A Miocene age volcanic-hypabyssal structure comprising volcaniclastic deposits and mafic intrusions is exposed with vertical relief of ˜110 m on the side of Gergovie Plateau (Auvergne, France). Three main volcaniclastic facies are: (1) Fluidal tuff breccia composed of juvenile basalt and sediment clasts with dominantly fluidal shapes, with several combinations of basalt and sediment within individual clasts. (2) Thickly bedded lapilli tuff composed of varying proportions of fine-grained sediment derived from Oligocene-Miocene lacustrine marls and mudstones and basaltic lapilli, blocks, and bombs. (3) Planar-bedded tuff forming thin beds of fine to coarse ash-size sedimentary material and basalt clasts. Intrusive bodies in the thickly bedded lapilli tuff range from irregularly shaped and anastomosing dikes and sills of meters to tens of meters in length, to a main feeder dike that is up to ˜20 m wide, and that flares into a spoon-shaped sill at ˜100 m in diameter and 10-20 m thick in the eastern part of the structure. Volcaniclastic deposits and structural features suggest that ascending magma entrained soft, saturated sediment host material into the feeder dike and erupted fluidal magma and wet sediment via weak, Strombolian-like explosions. Host sediment and erupted material subsided to replace the extracted sediments, producing the growth subsidence structure that is similar to upper diatreme facies in typical maar diatremes but lacks evidence for explosive disruption of diatreme fill. Irregularly shaped small intrusions extended from the main feeder dike into the diatreme, and many were disaggregated due to shifting and subsidence of diatreme fill and recycled via eruption. The Mardoux structure is an "unconventional" maar diatreme in that it was produced mainly by weak explosive activity rather than by violent phreatomagmatic explosions and is an example of complex coupling between soft sediment and ascending magma.

Geologic controls on the formation of lakes in north-central Florida

USGS Publications Warehouse

Kindinger, Jack G.; Davis, Jeffrey B.; Flocks, James G.; Pitman, Janet K.; Carroll, Alan R.

1998-01-01

Fluid exchange between surficial waters and groundwater, as well as the processes that control this exchange, are of critical concern to water management districts and planners. Digital high-resolution seismic systems were used to collect geophysical data from 30 lakes of north-central Florida. Although using seismic profile data in the past has been less than successful, the use of digital technology has increased the potential for success. Seismic profiles collected from the lakes of north-central Florida have shown the potential application of these techniques in understanding the formation of individual lakes. In each case study, lake structure and geomorphology were controlled by solution and/or mechanical processes. Processes that control lake development are twofold: 1) karstification or dissolution of the underlying limestone, and 2) me collapse, subsidence, or slumping of overburden to form sinkholes. Initial lake formation is directly related to the karst topography of the underlying host limestone. Lake size and shape are a factor of the thickness of overburden and size of the collapse or subsidence and/or clustering of depressions allowing for lake development. Lake development is through progressive sequence stages to maturity that can be delineated into geomorphic types. Case studies have shown that lakes can be divided by geomorphic types into progressive developmental phases: (1) active subsidence or collapse phase (young) - the open to partially filled collapse structures typically associated with sink holes; (2) transitional phase (middle age) - the sinkhole is plugged as the voids within the collapse are filled with sediment, periodic reactivation may occur; (3) baselevel phase (mature) - active sinkholes are progressively plugged by the continual erosion of material into the basin, and eventually sediment fills the basins; and (4) polje (drowned prairie) - broad flat-bottom basins located within the epiphreatic zone that are inundated at high stages of the water table and have one or all phases of sinkhole development and many types of karst and karren features. Most lakes in this study have a small diameter (

Subsidence Monitoring in Seville (S Spain) Using Multi-Temporal InSAR

NASA Astrophysics Data System (ADS)

Ruiz-Armenteros, Antonio M.; Ruiz-Constan, Ana; Lamas-Fernandez, Francisco; Galindo-Zaldivar, Jesus; Sousa, Joaquim J.; Sanz de Galdeano, Carlos; Delgado, Manuel J.; Pedrera-Parias, Antonio; Martos-Rosillo, Sergio; Gil, Antonio J.; Caro-Cuenca, Miguel; Hanssen, Ramon F.

2016-08-01

Seville, with a metropolitan population of about 1.5 million, is the capital and largest city of Andalusia (S Spain). It is the 30th most populous municipality in the European Union and contains three UNESCO World Heritage Sites. The Seville harbour, located about 80 km from the Atlantic Ocean, is the only river port in Spain. The city is located on the plain of the Guadalquivir River. Using Multi-Temporal InSAR with ERS-1/2 and Envisat data a subsidence behavior is detected in the period 1992-2010. The geometry of the subsiding areas suggests that it should be conditioned by the fluvial dynamics of the Guadalquivir River and its tributaries. Facies distribution along the fluvial system (paleochannels, flood plains...), with different grain size and matrix proportion, may explain the relative subsidence between the different sectors.

Stability Analysis of Railway Subgrade in Mining Area Based on Dinsar

NASA Astrophysics Data System (ADS)

Xu, J.; Hu, J.; Ding, J.

2018-04-01

DInSAR technology have been applied to monitor the mining subsidence and the stability of the railway subgrade. A total of 10 Sentinel-1A images acquired from 2015/9/26 to 2016/2/23 were used in DInSAR analysis. The study mining area is about 13.4 km2. Mining have induced serious land subsidence involve a large area that causing different levels of damages to infrastructures on the land. There is an important railway near the mining area, the DInSAR technology is applied to analyse the subsidence near the railway, which can warn early the possible deformation that may occur during underground mining. The DInSAR results was verified by the field measurement. The results show that the mining did not cause subsidence of railway subgrade and did not affect the stability of railway subgrade.

The geomorphological evidences of subsidence in the Nile Delta: Analysis of high resolution topographic DEM and multi-temporal satellite images

NASA Astrophysics Data System (ADS)

El Bastawesy, M.; Cherif, O. H.; Sultan, M.

2017-12-01

This paper investigates the relevance of landforms to the subsidence of the Nile Delta using a high resolution topographic digital elevation model (DEM) and sets of multi-temporal Landsat satellite images. 195 topographic map sheets produced in 1946 at 1:25,000 scale were digitized, and the DEM was interpolated. The undertaken processing techniques have distinguished all the natural low-lying closed depressions from the artificial errors induced by the interpolation of the DEM. The local subsidence of these depressions from their surroundings reaches a maximum depth of 2.5 m. The regional subsidence of the Nile Delta has developed inverted topography, where the tracts occupied by the contemporary distributary channels are standing at higher elevations than the areas in between. This inversion could be related to the differences in the hydrological and sedimentological properties of underlying sediments, as the channels are underlain by water-saturated sands while the successions of clay and silt on flood plains are prone to compaction. Furthermore, the analysis of remote sensing and topographic data clearly show significant changes in the land cover and land use, particularly in the northern lagoons and adjacent sabkhas, which are dominated by numerous low subsiding depressions. The areas covered by water logging and ponds are increasing on the expense of agricultural areas, and aquaculture have been practiced instead. The precise estimation of subsidence rates and distribution should be worked out to evaluate probable changes in land cover and land use.

Land subsidence in the southwestern Mojave Desert, California, 1992–2009

USGS Publications Warehouse

Brandt, Justin; Sneed, Michelle

2017-07-19

Groundwater has been the primary source of domestic, agricultural, and municipal water supplies in the southwestern Mojave Desert, California, since the early 1900s. Increased demands on water supplies have caused groundwater-level declines of more than 100 feet (ft) in some areas of this desert between the 1950s and the 1990s (Stamos and others, 2001; Sneed and others, 2003). These water-level declines have caused the aquifer system to compact, resulting in land subsidence. Differential land subsidence (subsidence occurring at different rates across the landscape) can alter surface drainage routes and damage surface and subsurface infrastructure. For example, fissuring across State Route 247 at Lucerne Lake has required repairs as has pipeline infrastructure near Troy Lake.Land subsidence within the Mojave River and Morongo Groundwater Basins of the southwestern Mojave Desert has been evaluated using InSAR, ground-based measurements, geology, and analyses of water levels between 1992 and 2009 (years in which InSAR data were collected). The results of the analyses were published in three USGS reports— Sneed and others (2003), Stamos and others (2007), and Solt and Sneed (2014). Results from the latter two reports were integrated with results from other USGS/ MWA cooperative groundwater studies into the broader scoped USGS Mojave Groundwater Resources Web site (http://ca.water.usgs.gov/ mojave/). This fact sheet combines the detailed analyses from the three subsidence reports, distills them into a longer-term context, and provides an assessment of options for future monitoring.

Impact of post-mining subsidence on nitrogen transformation in southern tropical dry deciduous forest, India

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, N.; Singh, R.S.; Singh, J.S.

The goal of our research was to assess the impact of post-mining land subsidence, caused due to underground coal mining operations, on fine root biomass and root tips count; plant available nutrient status, microbial biomass N (MBN) and N-mineralization rates of a Southern tropical dry deciduous forest of Singareni Coalfields of India. The changes were quantified in all the three (rainy, winter and summer) seasons, in slope and depression microsites of the subsided land and an adjacent undamaged forest microsite. Physico-chemical characteristics were found to be altered after subsidence, showing a positive impact of subsidence on soil moisture, bulk density,more » water holding capacity, organic carbon content, total N and total P. The increase in all the parameters was found in depression microsites, while in slope microsites, the values were lower. Fine root biomass and root tips count increased in the subsided depression microsites, as demonstrated by increases of 62% and 45%, respectively. Soil nitrate-N and phosphate-P concentrations were also found to be higher in depression microsite, showing an increase of 35.68% and 24.74%, respectively. Depression microsite has also shown the higher MBN value with an increase over control. Net nitrification, net N-mineralization and MBN were increased in depression microsite by 29.77%, 25.72% and 34%, respectively. There was a positive relation of microbial N with organic C, fine root biomass and root tips.« less