Filtering by Subject: Geophysics and Seismology

Gradient-boosted equivalent sources

Santiago Rubén Soler, Leonardo Uieda

Published: 2021-02-25
Subjects: Earth Sciences, Geophysics and Seismology

The equivalent source technique is a powerful and widely used method for processing gravity and magnetic data. Nevertheless, its major drawback is the large computational cost in terms of processing time and computer memory. We present two techniques for reducing the computational cost of equivalent source processing: block-averaging source locations and the gradient-boosted equivalent source [...]

Episodicity and Migration of Low Frequency Earthquakes modeled with Fast Fluid Pressure Transients in the Permeable Subduction Interface

Gaspard Farge, Claude Jaupart, Nikolai M. Shapiro

Published: 2021-02-24
Subjects: Geophysics and Seismology

In many subduction zones, the plate interface hosts intermittent, low-frequency, low-magnitude seismic tremor and low-frequency earthquakes (LFEs). Episodically, activity clusters in bursts that migrate along the fault zone in complex ways. Geological observations report a pervasive imprint of intense fluid pressure and permeability variations in the tremor source region. The dynamics of such [...]

The surface deformation of the 2020 Doğanyol-Sivrice earthquake (Mw 6.8) and the earlier events suggest Mw˂7.0 earthquakes do not create significant surface slip along the East Anatolian Fault Zone

Kenan Akbayram, Kemal Kıranşan, Çağlar Özer, Sadık Varolgüneş

Published: 2021-02-18
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure

The 2020 Mw 6.8 Doğanyol-Sivrice earthquake occurred on the Pütürge Segment of the left-lateral East Anatolian Fault Zone (EAFZ). Our field investigation within 6 weeks after the earthquake suggests the following results. (1) The 2020 earthquake created a ~54-km-long surface deformation zone along the Pütürge Segment. (2) No co-seismic surface slip has been formed after the earthquake. (3) The [...]

Slip behaviors extracted from decadal seafloor geodesy after the Tohoku-oki earthquake

Shun-ichi Watanabe, Tadashi Ishikawa, Yuto Nakamura, Yusuke Yokota

Published: 2021-02-16
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics

Investigations of the co- and postseismic processes of the 2011 Tohoku-oki earthquake provide essential information on the seismic cycle in the Japan Trench. Although various postseismic models have been proposed, no consensus has been reached, especially on the along-strike extensions of the main rupture due to the lack of conclusive evidence, even in the coseismic process. To capture aseismic [...]

Acoustics from low-magnitude fluid-induced earthquakes in Finland

Oliver D. Lamb, Jonathan M Lees, Peter E Malin, Tero Saarno

Published: 2021-02-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Earthquakes are frequently accompanied by public reports of audible low-frequency noises. In 2018, public reports of booms or thunder-like noises were linked to induced earthquakes during a Engineered Geothermal System project in the Helsinki Metropolitan area. In response, two microphone arrays were deployed to study these acoustics while stimulation at the drill site continued. During the 11 [...]

Upper Mantle Radial Anisotropy Under the Indian Ocean from Higher Mode Surface Waves and a Hierarchical Transdismensional Approach

Erik Weidner, Caroline Beghein, Quancheng Huang, Nicholas Schmerr

Published: 2021-02-03
Subjects: Earth Sciences, Geophysics and Seismology

We investigated the likelihood of radial anisotropy in the shallow and deep upper mantle, including the mantle transition zone (MTZ) under the Indian Ocean. Seismic anisotropy can be an indicator of mantle deformation through lattice preferred orientation of anisotropic crystals in the mantle. It has thus the potential to illuminate Earth's dynamic interior, but previous seismic tomography [...]

Ordination analysis in sedimentology, geochemistry and paleoenvironment - background, current trends and recommendations

Or M. Bialik, Emilia Jarochowska, Michal Grossowicz

Published: 2021-02-01
Subjects: Biogeochemistry, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Multivariate Analysis, Oil, Gas, and Energy, Other Earth Sciences, Paleobiology, Paleontology, Sedimentology

Ordination is the name given to a group of methods used to analyze multiple variables without preceding hypotheses. Over the last few decades the use of these methods in Earth science in general, and notably in analyses of sedimentary sources, has dramatically increased. However, with limited resources oriented towards Earth scientists on the topic, the application of ordination analysis is at [...]

Back-propagating rupture evolution within a curved slab during the 2019 Peru intraslab earthquake

Hu Yaping, Yagi Yuji, Okuwaki Ryo, Kousuke Shimizu

Published: 2021-01-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

The 26 May 2019 Mw 8.0 Peru intraslab earthquake ruptured the subducting Nazca plate at a point where the dip angle of the slab increases sharply and the strike angle rotates clockwise from the epicenter to north. To obtain a detailed seismic source model of the 2019 Peru earthquake, including not only the rupture evolution but also the spatiotemporal distribution of focal mechanisms, we [...]

Learning in a Crisis: Online Skill Building Workshop Addresses Immediate Pandemic Needs and Offers Possibilities for Future Trainings

Michael R Brudzinski, Shannon Fasola, Michael Hubenthal, Em Schnorr

Published: 2021-01-28
Subjects: Computer Sciences, Earth Sciences, Education, Geophysics and Seismology, Scholarship of Teaching and Learning

The COVID-19 pandemic led to the suspension of many summer research opportunities for STEM students. In response, the IRIS Education and Outreach program, in collaboration with Miami University, offered a free online Seismology Skill Building Workshop to increase undergraduates' knowledge, skills, self-efficacy, and interest in observational seismology and scientific computing. Registrations were [...]

101 Geodynamic modelling: How to design, carry out, and interpret numerical studies

Iris van Zelst, Fabio Crameri, Adina E Pusok, Anne C Glerum, Juliane Dannberg, Cedric Thieulot

Published: 2021-01-27
Subjects: Geophysics and Seismology

Geodynamic modelling provides a powerful tool to investigate processes in the Earth's crust, mantle, and core that are not directly observable. However, numerical models are inherently subject to the assumptions and simplifications on which they are based. In order to use and review numerical modelling studies appropriately, one needs to be aware of the limitations of geodynamic modelling as well [...]

Observational estimates of dynamic topography through space and time

Mark Hoggard, Jacqueline Austermann, Cody Randel, Simon Stephenson

Published: 2021-01-24
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure, Volcanology

Earth's mantle undergoes convection on million-year timescales as heat is transferred from depth to the surface. Whilst this flow has long been linked to the large-scale horizontal forces that drive plate tectonics and supercontinent cycles, geologists are increasingly recognising the signature of convection through transient vertical motions in the rock record, known as "dynamic topography". A [...]

Earthquake rupture on multiple splay faults and its effect on tsunamis

Iris van Zelst, Leonhard Rannabauer, Alice-Agnes Gabriel, Ylona van Dinther

Published: 2021-01-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Detailed imaging of accretionary wedges reveal complex splay fault networks which could pose a significant tsunami hazard. However, the dynamics of multiple splay fault activation and interaction during megathrust events and consequent effects on tsunami generation are not well understood. We use a 2D dynamic rupture model with six complex splay fault geometries consistent with initial stress [...]

Integrated magnetotelluric and petrological analysis of felsic magma reservoirs: Insights from Ethiopian rift volcanoes

Friedemann Samrock, Alexander V. Grayver, Olivier Bachmann, Özge Karakas, Martin O Saar

Published: 2021-01-16
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Volcanology

Geophysical and petrological probes are key to understanding the structure and the thermochemical state of active magmatic systems. Recent advances in laboratory analyses, field investigations and numerical methods have allowed increasingly complex data-constraint models with new insights into magma plumbing systems and melt evolution. However, there is still a need for methods to quantitatively [...]

Time to Depth Seismic Reprocessing of Vintage Data: a Case Study in the Otranto Channel (South Adriatic Sea)

Giuseppe Brancatelli, Edy Forlin, Nicolò Bertone, Anna Del Ben, Riccardo Geletti

Published: 2021-01-14
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics

In this chapter, we present a case study focused on the reprocessing of marine seismic line MS-29, acquired in 1971 in the Otranto Channel, in the South Adriatic Sea (Italy). This line crosses the channel between South Italy and Albania, a key location for understanding the geodynamics of the North Adria Plate. The work is divided into two steps. The first step consists of a modern broadband [...]

LASIF: LArge-scale Seismic Inversion Framework, an updated version

Solvi Thrastarson, Dirk-Philip van Herwaarden, Lion Krischer, Andreas Fichtner

Published: 2021-01-07
Subjects: Geophysics and Seismology, Numerical Analysis and Scientific Computing, Software Engineering

Recent methodological advances and increases in computational power have made it feasible to perform full-waveform inversions (FWI) of large domains while using more sources. This trend, along with the increasing availability of seismic data has led to an explosion of the data volumes that can, and should, be used within an inversion. Similar to machine learning problems, the incorporation of [...]


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