Filtering by Subject: Geophysics and Seismology

Resolving the location of small intracontinental earthquakes using Open Access seismic and geodetic data: lessons from the 18 January 2017 mb 4.3, Niger, earthquake

Timothy J Craig, Steven J. Gibbons

Published: 2022-01-14
Subjects: Geophysics and Seismology, Tectonics and Structure

A low-magnitude earthquake was recorded on January 18, 2017, in the T\'{e}n\'{e}r\'{e} desert in Niger. This intraplate region is exceptionally sparsely covered with seismic stations and the closest open seismic station, G.TAM in Algeria at a distance of approximately 600 km, was unusually and unfortunately not operational at the time of the event. Body-wave magnitude estimates range from $m_b [...]

Variations in Earth's 1D viscosity structure in different tectonic regimes

Anthony Osei Tutu, Christopher Harig

Published: 2022-01-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

Earth’s long-wavelength geoid provides insights into the thermal, structural, and compositional evolution of the mantle. Historically, most estimates of mantle viscosity using the long-wavelength geoid have considered radial variations with depth in a symmetric Earth. Global estimates of this kind suggest an increase in viscosity from the upper mantle to lower mantle of roughly 2 -- 3 orders of [...]

Experimental multiblast craters and ejecta — seismo-acoustics, jet characteristics, craters, and ejecta deposits and implications for volcanic explosions

Ingo Sonder, Alison H. Graettinger, Tracianne B. Neilsen, et al.

Published: 2022-01-09
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology

Blasting experiments were performed that investigate multiple explosions that occur in quick succession in the ground and their effects on host material and atmosphere. Such processes are known to occur during volcanic eruptions at various depths, lateral locations, and energies. The experiments follow a multi-instrument approach in order to observe phenomena in the atmosphere and in the ground, [...]

Seismic velocity recovery in the subsurface: transient damage and groundwater drainage following the 2015 Gorkha earthquake, Nepal

Luc Illien, Christoph Sens-Schönfelder, Christoph Andermann, et al.

Published: 2022-01-04
Subjects: Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics

Shallow earthquakes frequently disturb the hydrological and mechanical state of the subsurface, with consequences for hazard and water management. Transient post-seismic hydrological behaviour has been widely reported, suggesting that the recovery of material properties (relaxation) following ground shaking may impact groundwater fluctuations. However, the monitoring of seismic velocity [...]

Structural traps and seals for expanding CO2 storage in the northern Horda Platform, North Sea

Johnathon Lee Osmond, Mark Joseph Mulrooney, Nora Holden, et al.

Published: 2021-12-24
Subjects: Geology, Geophysics and Seismology, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Stratigraphy, Tectonics and Structure

The maturation of geological CCS along the Norwegian Continental Shelf is ongoing in the Norwegian North Sea, however, more storage sites are needed to reach climate mitigation goals by 2050. In order to augment the Aurora site and expand CO2 storage in the northern Horda Platform, regional traps and seals must be assessed to better understand the area’s potential. Here, we leverage wellbore and [...]

Imaging evolution of Cascadia slow-slip event using high-rate GPS

Yuji Itoh, Yosuke Aoki, Junichi Fukuda

Published: 2021-12-24
Subjects: Earth Sciences, Geophysics and Seismology, Tectonics and Structure

The slip history of short-term slow slip event (SSE) is typically inferred from daily Global Positioning System (GPS) data, which, however, cannot image the sub-daily processes, leaving the underlying mechanisms of SSEs elusive. To address the temporal resolution issue, we attempted to employ the kinematic subdaily GPS analysis, which has never been applied to SSE studies because its [...]

Matched Field Processing for complex Earth structure

Sven Schippkus, Celine Hadziioannou

Published: 2021-12-16
Subjects: Geophysics and Seismology

Matched Field Processing (MFP) is a technique to locate the source of a recorded wave field. It is the generalization of beamforming, allowing for curved wavefronts. In the standard approach to MFP, simple analytical Green's functions are used as synthetic wave fields that the recorded wave fields are matched against. We introduce an advancement of MFP by utilizing Green's functions computed [...]

Thermochemical structure and evolution of cratonic lithosphere in central and southern Africa

Juan Carlos Afonso, Walid Ben Mansour, Suzanne Y O’Reilly, et al.

Published: 2021-12-11
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Tectonics and Structure

The thermochemical structure of the subcontinental mantle holds crucial information on its origin and evolution that can inform energy and mineral exploration strategies, natural haz-ard mitigation and evolutionary models of the Earth1−4. However, imaging the fine-scale thermochemical structure of continental lithosphere remains a major challenge. Here we combine multiple land and satellite [...]

External surface water influence on explosive eruption dynamics, with implications for stratospheric sulfur delivery and volcano-climate feedback

Colin Rowell, Mark Jellinek, Sahand Hajimirza, et al.

Published: 2021-12-09
Subjects: Fluid Dynamics, Geophysics and Seismology, Volcanology

Explosive volcanic eruptions can inject sulfur dioxide (SO2) into the stratosphere to form aerosol particles that modify Earth’s radiation balance and drive surface cooling. Eruptions involving interactions with shallow layers (< 500 m) of surface water and ice modify the eruption dynamics that govern the delivery of SO2 to the stratosphere. External surface water potentially controls the [...]

Deep Coseismic Slip in the Cascadia Megathrust can be Consistent with Coastal Subsidence

Diego Melgar, Valerie Sahakian, Amanda Thomas

Published: 2021-12-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

At subduction zones, the down-dip limit of slip represents how deep an earthquake can rupture. For hazards it is important - it controls the intensity of shaking and the pattern of coseismic uplift and subsidence. In the Cascadia Subduction Zone, because no large magnitude events have been observed in instrumental times, the limit is inferred from geological estimates of coastal subsidence during [...]

Self-limiting earthquake dynamics and spatio-temporal clustering of seismicity enabled by off-fault plasticity

Md Shumon Mia, Mohamed Abdelmeguid, Ahmed Elbanna

Published: 2021-12-06
Subjects: Applied Mechanics, Civil and Environmental Engineering, Dynamics and Dynamical Systems, Earth Sciences, Engineering, Engineering Mechanics, Engineering Science and Materials, Geophysics and Seismology, Mechanical Engineering, Mechanics of Materials, Other Mechanical Engineering, Physical Sciences and Mathematics, Tribology

Earthquakes are among nature’s deadliest and costliest hazards. Understanding mechanisms for earthquake nucleation, propagation, and arrest is key for developing reliable operational forecasts and next generation seismic hazard models. While significant progress has been made in understanding source processes in linear elastic domains, the response of the rocks near the fault is complex and [...]

Can machine learning improve carbon storage? Synergies of deep learning, uncertainty quantification and intelligent process control

Thilo Wrona, Indranil Pan

Published: 2021-12-02
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Sustainability

As we transition from fossil fuel to renewable energy, negative emission technologies, such ascarbon capture and storage (CCS), can help us reduce CO2 emissions. Effective CO2 storage requires: (1) detailed site characterization, (2) regular, integrated risk assessment, and (3) flexible design and operation. We believe that recent advances in machine learning coupled with uncertainty [...]

Sensitivity of horizontal surface deformation to mantle dynamics from 3D instantaneous dynamics modeling of the eastern Mediterranean region

Anne C Glerum, Wim Spakman, Douwe J.J. van Hinsbergen, et al.

Published: 2021-11-29
Subjects: Geophysics and Seismology, Tectonics and Structure

Geodetically estimated surface motions contain contributions to crustal deformation from coupled geodynamic processes active at all spatial scales and constitute key data for lithosphere dynamics research. Data interpretation methods should therefore account for the full range of possible processes, otherwise risking misinterpretation of data signal and incorrect estimation of lithosphere [...]

An optimization method for paleomagnetic Euler pole analysis

Leandro Cesar Gallo, Facundo Sapienza, Mathew Domeier

Published: 2021-11-16
Subjects: Geology, Geophysics and Seismology

Owing to the inherent axial symmetry of the Earth’s magnetic field, paleomagnetic data only directly record the latitudinal and azimuthal positions of crustal blocks in the past, but paleolongitude cannot be constrained. An ability to overcome this obstacle is fundamental to paleogeographic reconstruction. The paleomagnetic Euler pole (PEP) analysis presents a unique means to recover such [...]

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 [...]


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