Ground motions induced by pore pressure changes at the Szentes geothermal area, SE Hungary

2021 ◽  
Author(s):  
Eszter Békési ◽  
Peter Fokker ◽  
Thibault Candela ◽  
János Szanyi ◽  
Jan-Diederik van Wees
Keyword(s):  
Pressure Drop ◽  
Thermal Water ◽  
Surface Deformation ◽  
Ground Motions ◽  
Regional Scale ◽  
Model Parameters ◽  
Geothermal Reservoirs ◽  
Reservoir System ◽  
Basin Scale ◽  
Compaction Behaviour

<p>The long-term sustainable exploitation of geothermal resources requires cautious planning and regulation. Exploitation in excess of natural recharge can result in reservoir pressure decline, causing a decrease in production rates. Furthermore, such “overexploitation” of geothermal reservoirs may lead to compaction and land subsidence. Understanding of such phenomena is critical for the assessment of societal-environmental risks, but can also be used for optimization by constraining reservoir processes and properties.</p><p>Excessive thermal water volumes have been extracted from porous sedimentary rocks in the Hungarian part of the Pannonian Basin. Thermal water production in Hungary increased significantly from the early 70’s. Regional-scale overexploitation of geothermal reservoirs resulted in basin-scale pressure drop in the Upper Pannonian sediments, leading to compaction and ground subsidence.</p><p>We investigated surface deformation at the Szentes geothermal filed, SE Hungary, where the largest pressure decline occurred. We obtained data from the European Space Agency’s ERS and Envisat satellites to estimate the ground motions for the periods of 1992-2000 and 2002-2010. We applied inverse geomechanical modelling to understand the compaction behaviour of the reservoir system and to estimate the subsurface properties. We constrained the model parameters using the Ensemble Smoother with Multiple Data Assimilation, which allowed us to incorporate large amounts of surface movement observations in a computationally efficient way. The model requires pressure time series as input parameters, therefore, the lack of regular pressure measurements in geothermal wells of Szentes resulted in significant uncertainties. Still, we managed to identify a potential delay in pressure drop and subsidence, implying a time-decay compaction behaviour of the reservoir system,  and we arrived at realistic estimates for the compaction coefficient of the reservoir. The improved parametrization enables better forecasting of the reservoir behaviour and facilitates the assessment of future subsidence scenarios. This study thus demonstrates the effectiveness of InSAR-based ground motion data and inverse geomechanical modelling for the monitoring of geothermal reservoirs and the establishment of a sustainable production scheme.</p>

scholarly journals Coupling of regional geophysics and local soil-structure models in the EQSIM fault-to-structure earthquake simulation framework

2021 ◽  
pp. 109434202110191
Author(s):  
David McCallen ◽  
Houjun Tang ◽  
Suiwen Wu ◽  
Eric Eckert ◽  
Junfei Huang ◽  
...  
Keyword(s):  
Soil Structure ◽  
Ground Motions ◽  
Regional Scale ◽  
Historical Earthquakes ◽  
Department Of Energy ◽  
Simulation Framework ◽  
Data Set ◽  
Major Barrier ◽  
Local Soil ◽  
Computational Workflow

Accurate understanding and quantification of the risk to critical infrastructure posed by future large earthquakes continues to be a very challenging problem. Earthquake phenomena are quite complex and traditional approaches to predicting ground motions for future earthquake events have historically been empirically based whereby measured ground motion data from historical earthquakes are homogenized into a common data set and the ground motions for future postulated earthquakes are probabilistically derived based on the historical observations. This procedure has recognized significant limitations, principally due to the fact that earthquake ground motions tend to be dictated by the particular earthquake fault rupture and geologic conditions at a given site and are thus very site-specific. Historical earthquakes recorded at different locations are often only marginally representative. There has been strong and increasing interest in utilizing large-scale, physics-based regional simulations to advance the ability to accurately predict ground motions and associated infrastructure response. However, the computational requirements for simulations at frequencies of engineering interest have proven a major barrier to employing regional scale simulations. In a U.S. Department of Energy Exascale Computing Initiative project, the EQSIM application development is underway to create a framework for fault-to-structure simulations. This framework is being prepared to exploit emerging exascale platforms in order to overcome computational limitations. This article presents the essential methodology and computational workflow employed in EQSIM to couple regional-scale geophysics models with local soil-structure models to achieve a fully integrated, complete fault-to-structure simulation framework. The computational workflow, accuracy and performance of the coupling methodology are illustrated through example fault-to-structure simulations.

scholarly journals Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

2021 ◽  
Author(s):  
Fabio Sabetta ◽  
Antonio Pugliese ◽  
Gabriele Fiorentino ◽  
Giovanni Lanzano ◽  
Lucia Luzi
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Stochastic Simulations ◽  
Model Parameters ◽  
Motion Model ◽  
Arias Intensity ◽  
Time Frequency ◽  
Ground Motion Model ◽  
Ground Motion Records

AbstractThis work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

Simulating and analyzing artificial nonstationary earthquake ground motions

1982 ◽  
Vol 72 (2) ◽  
pp. 615-636
Author(s):  
Robert F. Nau ◽  
Robert M. Oliver ◽  
Karl S. Pister
Keyword(s):  
Difference Equations ◽  
Kalman Filters ◽  
Ground Motions ◽  
Structural Response ◽  
Model Parameters ◽  
Time Varying ◽  
Nonparametric Method ◽  
Linear Difference Equations ◽  
Earthquake Ground Motions ◽  
Earthquake Accelerograms

Abstract This paper describes models used to simulate earthquake accelerograms and analyses of these artificial accelerogram records for use in structural response studies. The artificial accelerogram records are generated by a class of linear linear difference equations which have been previously identified as suitable for describing ground motions. The major contributions of the paper are the use of Kalman filters for estimating time-varying model parameters, and the development of an effective nonparametric method for estimating the variance envelopes of the accelerogram records.

scholarly journals Calibration and evaluation of a semi-distributed watershed model of Sub-Saharan Africa using GRACE data

2012 ◽  
Vol 16 (9) ◽  
pp. 3083-3099 ◽  
Author(s):  
H. Xie ◽  
L. Longuevergne ◽  
C. Ringler ◽  
B. R. Scanlon
Keyword(s):  
Regional Scale ◽  
Water Storage ◽  
Hydrologic Model ◽  
Sub Saharan Africa ◽  
Model Parameters ◽  
Total Water ◽  
Discharge Data ◽  
Model Based ◽  
Grace Data ◽  
Sub Saharan

Abstract. Irrigation development is rapidly expanding in mostly rainfed Sub-Saharan Africa. This expansion underscores the need for a more comprehensive understanding of water resources beyond surface water. Gravity Recovery and Climate Experiment (GRACE) satellites provide valuable information on spatio-temporal variability in water storage. The objective of this study was to calibrate and evaluate a semi-distributed regional-scale hydrologic model based on the Soil and Water Assessment Tool (SWAT) code for basins in Sub-Saharan Africa using seven-year (July 2002–April 2009) 10-day GRACE data and multi-site river discharge data. The analysis was conducted in a multi-criteria framework. In spite of the uncertainty arising from the tradeoff in optimising model parameters with respect to two non-commensurable criteria defined for two fluxes, SWAT was found to perform well in simulating total water storage variability in most areas of Sub-Saharan Africa, which have semi-arid and sub-humid climates, and that among various water storages represented in SWAT, water storage variations in soil, vadose zone and groundwater are dominant. The study also showed that the simulated total water storage variations tend to have less agreement with GRACE data in arid and equatorial humid regions, and model-based partitioning of total water storage variations into different water storage compartments may be highly uncertain. Thus, future work will be needed for model enhancement in these areas with inferior model fit and for uncertainty reduction in component-wise estimation of water storage variations.

scholarly journals Photosynthesis-irradiance parameters of marine phytoplankton: synthesis of a global data set

2017 ◽  
Author(s):  
Heather A. Bouman ◽  
Trevor Platt ◽  
Martina Doblin ◽  
Francisco G. Figueiras ◽  
Kristinn Gudmudsson ◽  
...  
Keyword(s):  
Primary Production ◽  
Broad Band ◽  
Marine Phytoplankton ◽  
Production Model ◽  
Initial Slope ◽  
Model Parameters ◽  
Data Set ◽  
Spatial Coverage ◽  
Basin Scale ◽  
Marine Primary Production

Abstract. The photosynthetic performance of marine phytoplankton varies in response to a variety of factors, environmental and taxonomic. One of the aims of the MArine primary Production: model Parameters from Space (MAPPS) project of the European Space Agency is to assemble a global database of photosynthesis-irradiance (P-E) parameters from a range of oceanographic regimes as an aid to examining the basin-scale variability in the photophysiological response of marine phytoplankton and to use this information to improve the assignment of P-E parameters in the estimation of global marine primary production using satellite data. The MAPPS P-E Database, which consists of over 5000 P-E experiments, provides information on the spatio-temporal variability in the two P-E parameters (the assimilation number, PmB, and the initial slope, αB, where the superscripts B indicate normalisation to concentration of chlorophyll) that are fundamental inputs for models (satellite-based and otherwise) of marine primary production that use chlorophyll as the state variable. Quality-control measures consisted of removing samples with abnormally-high parameter values and flags were added to denote whether the spectral quality of the incubator lamp was used to calculate a broad-band value of αB. The MAPPS database provides a photophysiological dataset that is unprecedented in number of observations and in spatial coverage. The database would be useful to a variety of research communities, including marine ecologists, biogeochemical modellers, remote-sensing scientists and algal physiologists. The compiled data are available at https://doi.org/10.1594/PANGAEA.874087 (Bouman et al., 2017).

Epithermal Precious Metal Deposits in South Korea—History and Pursuit

SEG Discovery ◽  
2021 ◽  
pp. 19-26
Author(s):  
Paul D. Wittwer
Keyword(s):  
South Korea ◽  
Precious Metal ◽  
Tectonic Setting ◽  
Regional Scale ◽  
Mining Operation ◽  
Mining Operations ◽  
Historical Mining ◽  
Mining Areas ◽  
Basin Scale ◽  
Gold Silver

Abstract The gold and silver endowment of Korea has historically been well known, with records alluding to production as far back as 1122 BC. The main gold production period was from 1925 to 1943 during the Japanese occupation of Korea, with more than 1 Moz recorded in 1939. Muguk was the most productive gold mining operation, located within the central region of South Korea, with a recorded 590 koz of gold produced from 1934 to 1998 (first mined in AD 912). The majority of the historical mining operations were closed by government order in 1943 during the Second World War and never reopened. A number of small mines operated between 1971 and 1998, with limited production during a period of gold prices generally lower than at present (~25–50% of current inflation adjusted prices, apart from a four-year period 1979–83). It is likely that significant resources remain within these historical mining areas. Gold-silver deposit types historically recognized and exploited in Korea include placers and orogenic and intrusion-related vein systems. Only more recently have epithermal vein and breccia systems been recognized. This is not surprising, given that the geologic and tectonic setting of the Southern Korean peninsula is prospective for epithermal precious metal deposits, spatially associated with basin-scale brittle fault systems in Cretaceous volcanic terranes. South Korea is an underexplored jurisdiction, with limited modern exploration and drilling until the mid-1990s, when Ivanhoe Mines Ltd. discovered the Gasado, Eunsan, and Moisan epithermal gold-silver deposits, all of which became mines. Exploration was limited for another 20 years until Southern Gold Ltd., an Australian Securities Exchange (ASX)-listed company, commenced regional-scale exploration for epithermal deposits, using a strategy similar to that successfully employed by Ivanhoe.

scholarly journals Evaluating the destabilization susceptibility of active rock glaciers in the French Alps

2019 ◽  
Vol 13 (1) ◽  
pp. 141-155 ◽  
Author(s):  
Marco Marcer ◽  
Charlie Serrano ◽  
Alexander Brenning ◽  
Xavier Bodin ◽  
Jason Goetz ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Regional Scale ◽  
Model Performance ◽  
Susceptibility Map ◽  
Rock Glacier ◽  
French Alps ◽  
Terrain Attributes ◽  
Rock Glaciers ◽  
Steep Terrain ◽  
Geomorphological Features

Abstract. In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A destabilization rating was assigned by taking into account the evolution of these mapped destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This destabilization rating then served as input to model the occurrence of rock glacier destabilization in relation to terrain attributes and to spatially predict the susceptibility to destabilization at a regional scale. Significant evidence of destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ∘C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30∘) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of destabilization. About 3 km2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to destabilization. Considering we observed that only half of these areas of creep are currently showing destabilization evidence, we suspect there is a high potential for future rock glacier destabilization within the French Alps.

scholarly journals Challenges in the Application of Fractional Derivative Models in Capturing Solute Transport in Porous Media: Darcy-Scale Fractional Dispersion and the Influence of Medium Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Yong Zhang ◽  
Charalambos Papelis ◽  
Michael H. Young ◽  
Markus Berli
Keyword(s):  
Fractional Derivative ◽  
Size Distribution ◽  
Fluid Velocity ◽  
Regional Scale ◽  
Glass Beads ◽  
Model Parameters ◽  
Late Time ◽  
Truncation Parameter ◽  
Fractional Derivative Model ◽  
Segregated Flow

Heterogeneous media consisting of segregated flow regions are fractional-order systems, where the regional-scale anomalous diffusion can be described by the fractional derivative model (FDM). The standard FDM, however, first, cannot characterize the Darcy-scale dispersion through repacked sand columns, and second, the link between medium properties and model parameters remains unknown. To fill these two knowledge gaps, this study applies a tempered fractional derivative model (TFDM) to capture bromide transport through laboratory repacked sand. Column transport experiments are conducted first, where glass beads and silica sand with different diameters are repacked individually. Late-time tails are observed in the breakthrough curves (BTC) of bromide even in relatively homogeneous glass beads. The TFDM can capture the observed subdiffusion, especially the late-time BTC with a transient declining rate. Results also show that both the size distribution of repacked sand and the magnitude of fluid velocity can affect subdiffusion. In particular, a wider sand size distribution or a smaller flow rate can enhance the subdiffusion, leading to a smaller time index and a higher truncation parameter in the TFDM. Therefore, the Darcy-scale dispersion follows the tempered stable law, and the model parameters might be related to the soil size and flow conditions.

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