Search for earthquake (320 results)

Weak, Seismogenic Faults Inherited From Mesozoic Rifts Control Mountain Building in the Andean Foreland

Sam Wimpenny

Published: 2021-11-15
Subjects: Earth Sciences

New earthquake focal mechanism and centroid depth estimates show that the deformation style in the forelands of the Andes is spatially correlated with rift systems that stretched the South American lithosphere in the Mesozoic. Where the rifts trend sub-parallel to the Andean range front, normal faults inherited from the rifts are being reactivated as reverse faults, causing the 30--45 km thick [...]

Simultaneous Inference of Plate Boundary Stresses and Mantle Rheology Using Adjoints: Large-Scale Two-Dimensional Models

Johann Rudi, Michael Gurnis, Georg Stadler

Published: 2021-11-08
Subjects: Earth Sciences, Geophysics and Seismology, Numerical Analysis and Scientific Computing

Plate motions are a primary surface constraint on plate and mantle dynamics and rheology, plate boundary stresses, and the occurrence of great earthquakes. Within an optimization method, we use plate motion data to better constrain uncertain mantle parameters. For the optimization problem characterizing the maximum a posteriori rheological parameters we derive gradients using adjoints and [...]

Collapse wedges in periglacial eolian sands imply Late Pleistocene paleoseismic activity of the Vienna Basin Transfer Fault (western Slovakia)

Michal Šujan, Samuel Rybár, Edit Thamó-Bozsó, et al.

Published: 2021-11-04
Subjects: Physical Sciences and Mathematics

Seismic hazard assessment is an important issue in geological research. Paleoseismological studies of the depositional record contribute significantly to our knowledge of earthquake recurrence over geological time, the distribution of seismically triggered deformations being an area of research that sheds light on temporal patterns of seismic activity. This paper describes soft sediment [...]

Persistent shallow micro-seismicity at Llaima volcano, Chile, with implications for long-term monitoring

Oliver Lamb, Jonathan M Lees, Luis Franco Marin, et al.

Published: 2021-11-01
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics, Volcanology

Identifying the source mechanisms of low-frequency earthquakes at ice-covered volcanoes can be challenging due to overlapping characteristics of glacially and magmatically derived seismicity. Here we present an analysis of two months of seismic data from Llaima volcano, Chile, recorded by the permanent monitoring network in 2019. We find over 2,000 repeating low-frequency events split across 82 [...]

From offshore to onshore probabilistic tsunami hazard assessment via efficient Monte-Carlo sampling

Gareth Davies, Rikki Weber, Kaya Wilson, et al.

Published: 2021-11-01
Subjects: Earth Sciences, Other Earth Sciences

Offshore Probabilistic Tsunami Hazard Assessments (offshore PTHAs) provide large-scale analyses of earthquake-tsunami frequencies and uncertainties in the deep ocean, but do not provide high-resolution onshore tsunami hazard information as required for many risk-management applications. To understand the implications of an offshore PTHA for the onshore hazard at any site, in principle the tsunami [...]

Potency density tensor inversion of complex body waveforms with time-adaptive smoothing constraint

SHINJI YAMASHITA, Yagi Yuji, Ryo Okuwaki, et al.

Published: 2021-10-28
Subjects: Physical Sciences and Mathematics

Large earthquakes are often accompanied by complex fault rupture, but it has been difficult to reliably estimate such a complex rupture process with conventional waveform analysis tools due to modelling errors originated from limited accuracy of the fault geometry. Recently, a potency density tensor inversion method has been developed to solve this problem; allowing any types of faulting [...]

The seismic wavefield as seen by Distributed Acoustic Sensing (DAS) arrays: local, regional and teleseismic sources

Brian L.N. Kennett

Published: 2021-10-20
Subjects: Earth Sciences, Physical Sciences and Mathematics

Distributed acoustic sensing (DAS) exploiting fibre optic cables provides a means for high-density sampling of the seismic wavefield. The scattered returns from multiple laser pulses provide local averages of strain rate over a finite gauge length, and the nature of the signal depends on the orientation of the cable with respect to the passing seismic waves. The properties of the wavefield in [...]

Kathmandu Basin as a local modulator of seismic waves: 2D modelling of nonlinear site response under obliquely incident waves

Elif Oral, Peyman Ayoubi, Jean Paul Ampuero, et al.

Published: 2021-10-15
Subjects: Civil Engineering, Earth Sciences, Geophysics and Seismology, Geotechnical Engineering

The 2015 Mw 7.8 Gorkha, Nepal earthquake is the largest event to have struck the capital city of Kathmandu in recent times. One of its surprising features was the frequency content of the recorded ground motion, exhibiting a notable amplification at low frequencies (< 2 Hz) and a contrasting depletion at higher frequencies. The latter has been partially attributed to the damper behaviour of the [...]

A Mixed, Unified Forward/Inverse Framework for Earthquake Problems: Fault Implementation and Coseismic Slip Estimate

Simone Puel, Eldar Khattatov, Umberto Villa, et al.

Published: 2021-10-06
Subjects: Earth Sciences, Geophysics and Seismology, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Tectonics and Structure

We introduce a new finite-element (FE) based computational framework to solve forward and inverse elastic deformation problems for earthquake faulting via the adjoint method. Based on two advanced computational libraries, FEniCS and hIPPYlib for the forward and inverse problems, respectively, this framework is flexible, transparent, and easily extensible. We represent a fault discontinuity [...]

Improved Seismic Monitoring with OBS Deployment in the Arctic: A Pilot Study from Offshore Western Svalbard

Zeinab Jeddi, Lars Ottemöller, Mathilde Bøttger Sørensen, et al.

Published: 2021-10-04
Subjects: Geophysics and Seismology

The mid-ocean ridge system is the main source of earthquakes within the Arctic region. The earthquakes are recorded on the permanent land-based stations in the region, although smaller earthquakes remain undetected. In this study, we make use of three Ocean Bottom Seismographs (OBSs) that were deployed offshore western Svalbard, along the spreading ridges. The OBS arrival times were used to [...]

Oblique convergence causes both thrust and strike-slip ruptures during the 2021 M 7.2 Haiti earthquake

Ryo Okuwaki, Wenyuan Fan

Published: 2021-10-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

A devastating magnitude 7.2 earthquake struck Southern Haiti on 14 August 2021. The earthquake caused severe damages and over 2000 casualties. Resolving the earthquake rupture process can provide critical insights into hazard mitigation. Here we use integrated seismological analyses to obtain the rupture history of the 2021 earthquake. We find the earthquake first broke a blind thrust fault and [...]

Structural controls on earthquake rupture revealed by the 2020 Mw 6.0 Jiashi earthquake (Kepingtag belt, SW Tian Shan, China)

Siyu Wang, Edwin Nissen, Timothy J Craig, et al.

Published: 2021-09-24
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure

The Kepingtag (Kalpin) fold-and-thrust belt of the southern Chinese Tian Shan is characterized by active shortening and intense seismic activity. Geological cross-sections and seismic reflection profiles suggest thin-skinned, northward-dipping thrust sheets detached in an Upper Cambrian décollement. The January 19 2020 Mw 6.0 Jiashi earthquake provides an opportunity to investigate how coseismic [...]

Shear-wave Anisotropy in the Earth’s Inner Core

Sheng Wang, Hrvoje Tkalčić

Published: 2021-09-17
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics

Earth’s inner core anisotropy is widely used to infer the deep Earth's evolution and present dynamics. Many compressional-wave anisotropy models have been proposed based on seismological observations. In contrast, inner-core shear-wave (J-wave) anisotropy – on a par with the compressional-wave anisotropy – has been elusive. Here we present a new class of the J-wave anisotropy observations [...]

Upper Plate Structure and Tsunamigenic Faults near the Kodiak Islands

Marlon Dale Ramos, Lee M Liberty, Peter J Haeussler, et al.

Published: 2021-09-17
Subjects: Physical Sciences and Mathematics

The Kodiak Islands lie near the southern terminus of the 1964 Great Alaska earthquake rupture area and within the Kodiak subduction zone segment. Both local and trans-Pacific tsunamis were generated during this devastating megathrust event, but the local tsunami source region and the causative faults are poorly understood. We provide an updated view of the tsunami and earthquake hazard for the [...]

Stress-based forecasting of induced seismicity with instantaneous earthquake failure functions: Applications to the Groningen Gas Reservoir.

Jonathan Daniel Smith, Elias Rafn Heimisson, Stephen Bourne, et al.

Published: 2021-09-15
Subjects: Geophysics and Seismology

The Groningen gas field is a natural laboratory to test stress-based forecasting models of induced seismicity due to the detailed knowledge of the reservoir geometry and production history, as well as the availability of surface subsidence measurements and high quality seismicity data. A specific feature of that case example is the exponential rise of seismicity that was detected nearly 30 years [...]


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