Articles | Volume 5, issue 2
https://doi.org/10.5194/se-5-1169-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/se-5-1169-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
26 Nov 2014
Research article |
| 26 Nov 2014
Wave-equation-based travel-time seismic tomography – Part 2: Application to the 1992 Landers earthquake (Mw 7.3) area
P. Tong
CORRESPONDING AUTHOR
Department of Physics, University of Toronto, Toronto, M5S 1A7, Ontario, Canada
D. Zhao
Department of Geophysics, Tohoku University, Sendai, Japan
D. Yang
Department of Mathematical Sciences, Tsinghua University, Beijing, China
X. Yang
Department of Mathematics, University of California, Santa Barbara, California, USA
J. Chen
Department of Mathematics, University of California, Santa Barbara, California, USA
Q. Liu
Department of Physics, University of Toronto, Toronto, M5S 1A7, Ontario, Canada
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A wave-equation-based travel-time seismic tomography method is developed including a detailed description of its step-by-step process. The forward problem is solved in the two-dimensional (2-D) vertical plane passing through the source and the receiver, and the final model is parameterized on 3-D inversion grid nodes. This 2-D--3D tomography method takes into account finite-frequency effects, accurately simulates seismic wave propagation in complex media, and has great computational efficiency.
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Teleseismic wave adjoint tomography is able to image the deep structure of the lithosphere. Here we proposed the element-by-element spectral-element method (EBE-SEM) for efficient teleseismic wave modeling. A detailed discussion of the teleseismic seismic incident boundary condition and PML absorbing boundary condition for the scattered waves are presented. Beside the high efficiency of EBE-SEM for the forward modeling of teleseismic waves, it is able to easily
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A wave-equation-based travel-time seismic tomography method is developed including a detailed description of its step-by-step process. The forward problem is solved in the two-dimensional (2-D) vertical plane passing through the source and the receiver, and the final model is parameterized on 3-D inversion grid nodes. This 2-D--3D tomography method takes into account finite-frequency effects, accurately simulates seismic wave propagation in complex media, and has great computational efficiency.
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A large amount of new seismic data from the greater Alpine area have been obtained within the AlpArray and SWATH-D projects. S-to-P converted seismic phases from the Moho and from the mantle lithosphere have been processed with a newly developed method. Examples of new observations are a rapid change in Moho depth at 13° E below the Tauern Window from 60 km in the west to 40 km in the east and a second Moho trough along the boundary of the Bohemian Massif towards the Western Carpathians.
Bogdan Grecu, Felix Borleanu, Alexandru Tiganescu, Natalia Poiata, Raluca Dinescu, and Dragos Tataru
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Ruth Keppler, Roman Vasin, Michael Stipp, Tomás Lokajícek, Matej Petruzálek, and Nikolaus Froitzheim
Solid Earth, 12, 2303–2326, https://doi.org/10.5194/se-12-2303-2021, https://doi.org/10.5194/se-12-2303-2021, 2021
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Mario Arroyo-Solórzano, Diego Castro-Rojas, Frédérick Massin, Lepolt Linkimer, Ivonne Arroyo, and Robin Yani
Solid Earth, 12, 2127–2144, https://doi.org/10.5194/se-12-2127-2021, https://doi.org/10.5194/se-12-2127-2021, 2021
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We present the first seismic noise variation levels during COVID-19 in Central America using 10 seismometers. We study the impact of the seismic noise reduction on the detectability of earthquakes and on the felt reports. Our results show maximum values (~50 % decrease) at seismic stations near airports and densely inhabited cities. The decrease in seismic noise improved earthquake locations and reports. Seismic noise could also be useful to verify compliance with lockdown measures.
Laura Peruzza, Alessandra Schibuola, Maria Adelaide Romano, Marco Garbin, Mariangela Guidarelli, Denis Sandron, and Enrico Priolo
Solid Earth, 12, 2021–2039, https://doi.org/10.5194/se-12-2021-2021, https://doi.org/10.5194/se-12-2021-2021, 2021
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In weakly seismic or poorly monitored areas, the uncritical use of earthquake catalogues can be misleading. This is the case for a central sector in the Po Valley, where the Northern Apennines and Southern Alps collide. We collect and reprocess the available instrumental data of about 300 earthquakes from 1951 to 2019. The seismicity is weak, deeper than expected, and far from some existing human activities carried out underground. The potential tectonic causative sources are still unknown.
Fabian Limberger, Michael Lindenfeld, Hagen Deckert, and Georg Rümpker
Solid Earth, 12, 1851–1864, https://doi.org/10.5194/se-12-1851-2021, https://doi.org/10.5194/se-12-1851-2021, 2021
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Frequency-dependent amplitude decays of seismic signals induced by wind turbines are determined from (up to) 6 months of continuous recordings measured along an 8 km profile located at a wind farm in Bavaria, Germany. The radiation pattern and amplitude decay of the induced signals are accounted for by an analytical approach that includes path and source effects. This approach is generalized to predict the characteristic seismic radiation patterns of arbitrary wind farm configurations.
Alessio Spurio Mancini, Davide Piras, Ana Margarida Godinho Ferreira, Michael Paul Hobson, and Benjamin Joachimi
Solid Earth, 12, 1683–1705, https://doi.org/10.5194/se-12-1683-2021, https://doi.org/10.5194/se-12-1683-2021, 2021
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The localization of an earthquake is affected by many uncertainties. To correctly propagate these uncertainties into an estimate of the earthquake coordinates and their associated errors, many simulations of seismic waves are needed. This operation is computationally very intensive, hindering the feasibility of this approach. In this paper, we present a series of deep-learning methods to produce accurate seismic traces in a fraction of the time needed with standard methods.
Marguerite Mathey, Christian Sue, Colin Pagani, Stéphane Baize, Andrea Walpersdorf, Thomas Bodin, Laurent Husson, Estelle Hannouz, and Bertrand Potin
Solid Earth, 12, 1661–1681, https://doi.org/10.5194/se-12-1661-2021, https://doi.org/10.5194/se-12-1661-2021, 2021
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This work features the highest-resolution seismic stress and strain fields available at the present time for the analysis of the active crustal deformation of the Western Alps. In this paper, we address a large dataset of newly computed focal mechanisms from a statistical standpoint, which allows us to suggest a joint control from far-field forces and from buoyancy forces on the present-day deformation of the Western Alps.
Marcel Paffrath, Wolfgang Friederich, and the AlpArray and AlpArray-SWATH D Working Groups
Solid Earth, 12, 1635–1660, https://doi.org/10.5194/se-12-1635-2021, https://doi.org/10.5194/se-12-1635-2021, 2021
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Using the AlpArray seismic network, we have determined highly accurate travel times of P waves from over 370 major global earthquakes between 2015 and 2019, which shall be used for a tomography of the mantle beneath the greater Alpine region.
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Itzhak Lior, Anthony Sladen, Diego Mercerat, Jean-Paul Ampuero, Diane Rivet, and Serge Sambolian
Solid Earth, 12, 1421–1442, https://doi.org/10.5194/se-12-1421-2021, https://doi.org/10.5194/se-12-1421-2021, 2021
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The increasing use of distributed acoustic sensing (DAS) inhibits the transformation of optical fibers into dense arrays of seismo-acoustic sensors. Here, DAS strain records are converted to ground motions using the waves' apparent velocity. An algorithm for velocity determination is presented, accounting for velocity variations between different seismic waves. The conversion allows for robust determination of fundamental source parameters, earthquake magnitude and stress drop.
Sarah Mader, Joachim R. R. Ritter, Klaus Reicherter, and the AlpArray Working Group
Solid Earth, 12, 1389–1409, https://doi.org/10.5194/se-12-1389-2021, https://doi.org/10.5194/se-12-1389-2021, 2021
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The Albstadt Shear Zone, SW Germany, is an active rupture zone with sometimes damaging earthquakes but no visible surface structure. To identify its segmentations, geometry, faulting pattern and extension, we analyze the continuous earthquake activity in 2011–2018. We find a segmented N–S-oriented fault zone with mainly horizontal and minor vertical movement along mostly NNE- and some NNW-oriented rupture planes. The main horizontal stress is oriented NW and due to Alpine-related loading.
Gesa Maria Petersen, Simone Cesca, Sebastian Heimann, Peter Niemz, Torsten Dahm, Daniela Kühn, Jörn Kummerow, Thomas Plenefisch, and the AlpArray and AlpArray-Swath-D working groups
Solid Earth, 12, 1233–1257, https://doi.org/10.5194/se-12-1233-2021, https://doi.org/10.5194/se-12-1233-2021, 2021
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The Alpine mountains are known for a complex tectonic history. We shed light onto ongoing tectonic processes by studying rupture mechanisms of small to moderate earthquakes between 2016 and 2019 observed by the temporary AlpArray seismic network. The rupture processes of 75 earthquakes were analyzed, along with past earthquakes and deformation data. Our observations point at variations in the underlying tectonic processes and stress regimes across the Alps.
Azam Jozi Najafabadi, Christian Haberland, Trond Ryberg, Vincent F. Verwater, Eline Le Breton, Mark R. Handy, Michael Weber, and the AlpArray and AlpArray SWATH-D working groups
Solid Earth, 12, 1087–1109, https://doi.org/10.5194/se-12-1087-2021, https://doi.org/10.5194/se-12-1087-2021, 2021
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This study achieved high-precision hypocenters of 335 earthquakes (1–4.2 ML) and 1D velocity models of the Southern and Eastern Alps. The general pattern of seismicity reflects head-on convergence of the Adriatic Indenter with the Alpine orogenic crust. The relatively deeper seismicity in the eastern Southern Alps and Giudicarie Belt indicates southward propagation of the Southern Alpine deformation front. The derived hypocenters form excellent data for further seismological studies, e.g., LET.
Javier Ojeda and Sergio Ruiz
Solid Earth, 12, 1075–1085, https://doi.org/10.5194/se-12-1075-2021, https://doi.org/10.5194/se-12-1075-2021, 2021
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In Santiago, Chile, the lockdown imposed due to COVID-19 was recorded by seismological instruments. This analysis shows temporal changes in the surface vibrations controlled by lockdown phases, mobility, and epidemiological factors. Our findings suggest that
dynamic lockdownand the early deconfinement in April 2020 caused an increase in mobility and therefore virus transmission. We propose that seismic networks could be used to monitor urban mobility as a new proxy in public policies.
Jiří Kvapil, Jaroslava Plomerová, Hana Kampfová Exnerová, Vladislav Babuška, György Hetényi, and AlpArray Working Group
Solid Earth, 12, 1051–1074, https://doi.org/10.5194/se-12-1051-2021, https://doi.org/10.5194/se-12-1051-2021, 2021
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This paper presents a high-resolution 3-D shear wave velocity (vS) model of the Bohemian Massif crust imaged from high-density data and enhanced depth sensitivity of tomographic inversion. The dominant features of the model are relatively higher vS in the upper crust than in its surrounding, a distinct intra-crustal interface, and a velocity decrease in the lower part of the crust. The low vS in the lower part of the crust is explained by the anisotropic fabric of the lower crust.
Martijn P. A. van den Ende and Jean-Paul Ampuero
Solid Earth, 12, 915–934, https://doi.org/10.5194/se-12-915-2021, https://doi.org/10.5194/se-12-915-2021, 2021
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Distributed acoustic sensing (DAS) is an emerging technology that measures stretching of an optical-fibre cable. This technology can be used to record the ground shaking of earthquakes, which offers a cost-efficient alternative to conventional seismometers. Since DAS is relatively new, we need to verify that existing seismological methods can be applied to this new data type. In this study, we reveal several issues by comparing DAS with conventional seismometer data for earthquake localisation.
Rebecca O. Salvage and David W. Eaton
Solid Earth, 12, 765–783, https://doi.org/10.5194/se-12-765-2021, https://doi.org/10.5194/se-12-765-2021, 2021
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Small earthquakes in Alberta and north-east British Columbia have been previously ascribed to industrial activities. The COVID-19 pandemic forced almost all these activities to stop for ~ 4 months. However, unexpectedly, earthquakes still occurred during this time. Some of these earthquakes may be natural and some the result of earthquakes > M6 occurring around the world. However, ~ 65 % of the earthquakes detected may be the remnants of previous fluid injection in the area (
latent seismicity).
Jordi Diaz, Mario Ruiz, and José-Antonio Jara
Solid Earth, 12, 725–739, https://doi.org/10.5194/se-12-725-2021, https://doi.org/10.5194/se-12-725-2021, 2021
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During the COVID-19 pandemic lockdown, the city of Barcelona was covered by a network of 19 seismometers. The results confirm that the quieting of human activity during lockdown has resulted in a reduction of seismic vibrations. The different lockdown phases in Barcelona are recognized consistently at most of the seismic stations. Our contribution demonstrates that seismic noise can be used as a free and reliable tool to monitor human activity in urban environments.
Raphael S. M. De Plaen, Víctor Hugo Márquez-Ramírez, Xyoli Pérez-Campos, F. Ramón Zuñiga, Quetzalcoatl Rodríguez-Pérez, Juan Martín Gómez González, and Lucia Capra
Solid Earth, 12, 713–724, https://doi.org/10.5194/se-12-713-2021, https://doi.org/10.5194/se-12-713-2021, 2021
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COVID-19 pandemic lockdowns in countries with a dominant informal economy have been a greater challenge than in other places. This motivated the monitoring of the mobility of populations with seismic noise throughout the various phases of lockdown and in the city of Querétaro (central Mexico). Our results emphasize the benefit of densifying urban seismic networks, even with low-cost instruments, to observe variations in mobility at the city scale over exclusively relying on mobile technology.
Maria Leonhardt, Grzegorz Kwiatek, Patricia Martínez-Garzón, Marco Bohnhoff, Tero Saarno, Pekka Heikkinen, and Georg Dresen
Solid Earth, 12, 581–594, https://doi.org/10.5194/se-12-581-2021, https://doi.org/10.5194/se-12-581-2021, 2021
Alexandr Smirnov, Marine De Carlo, Alexis Le Pichon, Nikolai M. Shapiro, and Sergey Kulichkov
Solid Earth, 12, 503–520, https://doi.org/10.5194/se-12-503-2021, https://doi.org/10.5194/se-12-503-2021, 2021
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Seismic and infrasound methods are techniques used to monitor natural events and explosions. At low frequencies, band signal can be dominated by microbaroms and microseisms. The noise observations in the Kazakh network are performed and compared with source and propagation modeling. The network is dense and well situated for studying very distant source regions of the ambient noise. The prospects are opening for the use of ocean noise in solid Earth and atmosphere tomography.
Mohammed Bello, David G. Cornwell, Nicholas Rawlinson, Anya M. Reading, and Othaniel K. Likkason
Solid Earth, 12, 463–481, https://doi.org/10.5194/se-12-463-2021, https://doi.org/10.5194/se-12-463-2021, 2021
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In this study, ground motion caused by distant earthquakes recorded in southeast Australia is used to image the structure of the crust and underlying mantle. This part of the Australian continent was assembled over the last 500 million years, but it remains poorly understood. By studying variations in crustal properties and thickness, we find evidence for the presence of an old microcontinent that is embedded in the younger terrane and forms a connection between Victoria and Tasmania.
Kasper van Wijk, Calum J. Chamberlain, Thomas Lecocq, and Koen Van Noten
Solid Earth, 12, 363–373, https://doi.org/10.5194/se-12-363-2021, https://doi.org/10.5194/se-12-363-2021, 2021
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The Auckland Volcanic Field is monitored by a seismic network. The lockdown measures to combat COVID-19 in New Zealand provided an opportunity to evaluate the performance of seismic stations in the network and to search for small(er) local earthquakes, potentially hidden in the noise during "normal" times. Cross-correlation of template events resulted in detection of 30 new events not detected by GeoNet, but there is no evidence of an increase in detections during the quiet period of lockdown.
Andrea Cannata, Flavio Cannavò, Giuseppe Di Grazia, Marco Aliotta, Carmelo Cassisi, Raphael S. M. De Plaen, Stefano Gresta, Thomas Lecocq, Placido Montalto, and Mariangela Sciotto
Solid Earth, 12, 299–317, https://doi.org/10.5194/se-12-299-2021, https://doi.org/10.5194/se-12-299-2021, 2021
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During the COVID-19 pandemic, most countries put in place social interventions, aimed at restricting human mobility, which caused a decrease in the seismic noise, generated by human activities and called anthropogenic seismic noise. In densely populated eastern Sicily, we observed a decrease in the seismic noise amplitude reaching 50 %. We found similarities between the temporal patterns of seismic noise and human mobility, as quantified by mobile-phone-derived data and ship traffic data.
Tieyuan Zhu, Junzhu Shen, and Eileen R. Martin
Solid Earth, 12, 219–235, https://doi.org/10.5194/se-12-219-2021, https://doi.org/10.5194/se-12-219-2021, 2021
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We describe the Fiber Optic foR Environmental SEnsEing (FORESEE) project in Pennsylvania, USA, the first continuous-monitoring distributed acoustic sensing (DAS) fiber array in the eastern USA. With the success of collecting 1 year of continuous DAS recordings using nearly 5 km of telecommunication fiber underneath the university campus, we conclude that DAS along with telecommunication fiber will potentially serve the purpose of continuous near-surface seismic monitoring in populated areas.
Manvendra Singh and Georg Rümpker
Solid Earth, 11, 2557–2568, https://doi.org/10.5194/se-11-2557-2020, https://doi.org/10.5194/se-11-2557-2020, 2020
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Using seismic array methods, 63 events were located in the Rodrigues–CIR region, not reported by any global network, most of them being off the ridge axis. The lack of seismicity along this section of the CIR, as observed from global data and this study, can possibly be attributed to the presence of partially molten mantle beneath Rodrigues Ridge. The results will be of interest for a broad range of geoscientists interested in the tectonic evolution of Indian Ocean and plume–crust interaction.
Valère Lambert and Nadia Lapusta
Solid Earth, 11, 2283–2302, https://doi.org/10.5194/se-11-2283-2020, https://doi.org/10.5194/se-11-2283-2020, 2020
Janneke van Ginkel, Elmer Ruigrok, and Rien Herber
Solid Earth, 11, 2015–2030, https://doi.org/10.5194/se-11-2015-2020, https://doi.org/10.5194/se-11-2015-2020, 2020
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Knowledge of subsurface velocities is key to understand how earthquake waves travel through the Earth. We present a method to construct velocity profiles for the upper sediment layer on top of the Groningen field, the Netherlands. Here, the soft-sediment layer causes resonance of seismic waves, and this resonance is used to compute velocities from. Recordings from large earthquakes and the background noise signals are used to derive reliable velocities for the deep sedimentary layer.
Ehsan Qorbani, Dimitri Zigone, Mark R. Handy, Götz Bokelmann, and AlpArray-EASI working group
Solid Earth, 11, 1947–1968, https://doi.org/10.5194/se-11-1947-2020, https://doi.org/10.5194/se-11-1947-2020, 2020
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The crustal structure of the Eastern and Southern Alps is complex. Although several seismological studies have targeted the crust, the velocity structure under this area is still not fully understood. Here we study the crustal velocity structure using seismic ambient noise tomography. Our high-resolution models image several velocity anomalies and contrasts and reveal details of the crustal structure. We discuss our new models of the crust with respect to the geologic and tectonic features.
Laura Ermert, Jonas Igel, Korbinian Sager, Eléonore Stutzmann, Tarje Nissen-Meyer, and Andreas Fichtner
Solid Earth, 11, 1597–1615, https://doi.org/10.5194/se-11-1597-2020, https://doi.org/10.5194/se-11-1597-2020, 2020
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We present an open-source tool to model ambient seismic auto- and cross-correlations with spatially varying source spectra. The modeling is based on pre-computed databases of seismic wave propagation, which can be obtained from public data providers. The aim of this tool is to facilitate the modeling of ambient noise correlations, which are an important seismologic observable, with realistic wave propagation physics. We present a description and benchmark along with example use cases.
Ben Moseley, Tarje Nissen-Meyer, and Andrew Markham
Solid Earth, 11, 1527–1549, https://doi.org/10.5194/se-11-1527-2020, https://doi.org/10.5194/se-11-1527-2020, 2020
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Simulations of seismic waves are very important; they allow us to understand how earthquakes spread and how the interior of the Earth is structured. However, whilst powerful, existing simulation methods usually require a large amount of computational power and time to run. In this research, we use modern machine learning techniques to accelerate these calculations inside complex models of the Earth.
Dominik Zbinden, Antonio Pio Rinaldi, Tobias Diehl, and Stefan Wiemer
Solid Earth, 11, 909–933, https://doi.org/10.5194/se-11-909-2020, https://doi.org/10.5194/se-11-909-2020, 2020
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The deep geothermal project in St. Gallen, Switzerland, aimed at generating electricity and heat. The fluid pumped into the underground caused hundreds of small earthquakes and one larger one felt by the local population. Here we use computer simulations to study the physical processes that led to the earthquakes. We find that gas present in the subsurface could have intensified the seismicity, which may have implications for future geothermal projects conducted in similar geological conditions.
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Short summary
The 1992 Landers earthquake area is chosen as the test field for the newly developed wave-equation based traveltime seismic tomography. The details of data selection, synthetic arrival-time determination, and trade-off analysis of damping and smoothing parameters are presented to show the performance of this tomographic inversion method. High-resolution crustal structures around the 1992 Lander earthquake area are obtained and help our understanding of the physical mechanism of the earthquakes.
The 1992 Landers earthquake area is chosen as the test field for the newly developed...
