A5008321225- earthquake and tectonic studies
- Seismic Waves and Analysis
- High-pressure geophysics and materials
- Seismic Imaging and Inversion Techniques
- Earthquake Detection and Analysis
- Fluid Dynamics and Mixing
- Seismology and Earthquake Studies
- Geological and Geochemical Analysis
- Minerals Flotation and Separation Techniques
- Seismic Performance and Analysis
- Innovative Microfluidic and Catalytic Techniques Innovation
- Geophysics and Sensor Technology
- Geological and Geophysical Studies Worldwide
- Geophysical Methods and Applications
- Risk and Safety Analysis
- Geological and Tectonic Studies in Latin America
- Structural Health Monitoring Techniques
- Geotechnical Engineering and Underground Structures
- Metallurgical Processes and Thermodynamics
- Pickering emulsions and particle stabilization
- Transport and Logistics Innovations
- Reservoir Engineering and Simulation Methods
- Numerical methods in engineering
- Drilling and Well Engineering
- Geophysics and Gravity Measurements
Charles University
2016-2025
Weizmann Institute of Science
2023
National Observatory
2021
University of Patras
2008
University of Žilina
2000-2005
Czech Academy of Sciences, Institute of Chemical Process Fundamentals
1991-2002
Czech Academy of Sciences
1997-2001
University of Wyoming
1994
James Madison University
1994
Czech Academy of Sciences, Institute of Geophysics
1972-1990
Research Article| July 01, 2013 Evaluating Centroid‐Moment‐Tensor Uncertainty in the New Version of ISOLA Software Efthimios Sokos; Sokos aUniversity Patras, Department Geology, Seismological Laboratory, 26504 Greeceesokos@upatras.gr Search for other works by this author on: GSW Google Scholar Jiří Zahradník bCharles University Prague, Faculty Mathematics and Physics, 18000 Czech Republicjiri.zahradnik@mff.cuni.cz Author Article Information Publisher: Society America First Online: 14 Jul...
Abstract Physical laws governing friction on shallow faults in the Earth and spatial heterogeneity of parameters are critical to our understanding earthquake physics assessment hazards. Here we use a laboratory-derived fault-friction law high-quality strong-motion seismic recordings 2020 Elazığ earthquake, Turkey, reveal complex rupture dynamics. We discover an initial Mw 5.8 stage explain how cascading behavior event, involving at least three episodes, each M > 6, caused it evolve into...
Abstract The increased seismic activity of the last ~10 years in Changning county Sichuan Province comprised just small (mostly M L < 5.0) injection‐induced earthquakes. W 5.7 earthquake on June 17, 2019, is largest event ever reported there. Moment tensor mainshock was remarkably dominated by a compensated linear vector dipole. We resolve its fine structure showing it doublet, allowing approximation thrust‐ and strike‐slip subevent. nucleated as thrust faulting, which (together with...
Key to studies of the rupture process is identification its major segmentation into asperities. Common multi-parametric methods invert for a continuous slip distribution; they usually rely on predefined fault position, nucleation point, planarity, smoothing, etc. Here we propose more flexible low-parametric inversions - multi-point seismic source models, and multi-patch GPS models. We study recent Mw 7.8 7.5 earthquakes in Eastern-Anatolian system, recorded high-quality near-regional network...
The moment tensor inversion for multiple point sources, based on Kikuchi and Kanamori (1991), was extended to full waveform data at regional (or local) distances. new code proved be efficient retrieving major source contributions of the 2003 Lefkada, Greece, earthquake. model derived from five three-component stations (epicentral distances <140 km), periods 10–20 s. Two main events dominated rupture process, one Lefkada Island (comprising three subevents total 0.9 × 1018 N m) other...
Finite‐difference (FD) modeling of complicated structures requires simple algorithms. This paper presents a new elastic FD method for spatially irregular grids that is and, at the same time, saves considerable memory and computing time. Features like faults, low‐velocity layers, cavities, and/or nonplanar surfaces are treated on fine grid, while remaining parts model are, with equal accuracy, represented coarse grid. No interpolation needed between due to rectangular grid cells. Relatively...
Abstract We present a method to assess the uncertainty of earthquake focal mechanisms based on standard theory linear inverse problems. compute moment tensor, M , then map it into uncertainties strike, dip, and rake. The inputs are: source station locations, crustal model, frequency band interest, an estimate data error. output is six‐dimensional (6D) error ellipsoid, which shows individual parameters . focus double‐couple (DC) part applicable both with without waveforms. latter particularly...
Abstract The M w 6.4 earthquake sequence of 2015 in western Greece is analyzed using seismic data. Multiple point source modeling, nonlinear slip patch, and linear inversions reveal a coherent rupture image with directivity toward the southwest several moment release episodes, reflected complex aftershock distribution. key feature that ruptured strong asperity, which was left unbroken between two large subevents 6.2 Lefkada doublet 2003. This finding well‐analyzed Cephalonia 2014 provide...
We have developed a new, fully automated tool for the centroid moment tensor (CMT) inversion in Bayesian framework. It includes data retrieval, selection where station components with various instrumental disturbances are rejected and full-waveform space–time grid around provided hypocentre. A covariance matrix calculated from pre-event noise yields an weighting of recordings according to their levels also serves as frequency filter suppressing noisy ranges. The method is tested on synthetic...
Moment tensors (MTs) of weak events are often calculated by a single agency (network), thus lacking independent validation. This article investigates how to increase reliability the single-agency solutions through various multiple checks. It deals with inversion complete waveforms for six representative (Mw 3.4-4.6) in range 0.08-0.15 Hz. Several three-station sets at near-regional distances (8-103 km) used. The MTs repeatedly two locations: from regional and local network. source depth is...
Abstract Broadband observations of small earthquakes at short epicentral distances reveal a mixture near-field effects and instrumental artifacts. We investigated these phenomena station equipped with an STS-2 CMG-40T sensor situated almost above shallow M 3.0 to 3.8 events (peak ground acceleration 2×10 -1 m/sec 2 ). The horizontal components were systematically accompanied by tiltlike disturbances, the tilt obtained from records exceeded more than 10 times values predicted source model....
We propose a new approach to resolve the isotropic component of seismic moment tensor and its uncertainty. In linearized inversion problems, where earthquake or explosive-source location origin time are fixed (e.g., assumed be known), uncertainty can studied through eigenvalues eigenvectors design matrix, which allows representation theo- retical misfit by means 6D error ellipsoid. Because matrix depends only on structural model receiver source geometry, analysis performed using recorded...
Research Article| November 01, 2014 A New Strategy for Weak Events in Sparse Networks: The First‐Motion Polarity Solutions Constrained by Single‐Station Waveform Inversion Lucia Fojtíková; Fojtíková aInstitute of Rock Structure and Mechanics, Academy Sciences the Czech Republic, V Holešovičkách 94/41, 182 09, Prague 8, Republicfojtikova@irsm.cas.cz Search other works this author on: GSW Google Scholar Jiří Zahradník bCharles University Prague, Faculty Mathematics Physics, Department...
Abstract Seismology illuminates physical processes occurring during underground explosions, not all yet fully understood. The thus‐far strongest North Korean test of 3 September 2017 was followed by a moderate seismic event ( m L 4.1) after 8.5 min. Here we provide evidence that this aftershock nontectonic which radiated waves as buried horizontal closing crack. This vigorous crack closure, shortly the blast, is studied in Korea site for first time. can be qualitatively explained rapid...
Abstract With different styles of faulting, the eastern Ionian Sea is an ideal natural laboratory to investigate interactions between adjacent faults during strong earthquakes. The 2018 Mw 6.8 Zakynthos earthquake, well recorded by broadband and strong-motion networks, provides opportunity resolve such faulting complexity. Here, we focus on waveform inversion backprojection data, partly checked coseismic Global Navigation Satellite System data. We show that region under subhorizontal...
Abstract We investigate a seismic crisis that occurred in the western Gulf of Corinth (Greece) between December 2020 and February 2021. This area is main focus Rift Laboratory (CRL) network, has been closely monitored with local seismological geodetic networks for 20 yr. The 2020–2021 evolved three stages: It started an Mw 4.6 event near northern shore Gulf, opposite Aigion, then migrated eastward toward Trizonia Island after 5.0 event, eventually culminated 5.3 ∼3 km northeast Psathopyrgos...