Filtering by Subject: Tectonics and Structure

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 [...]

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 [...]

A snapshot of the earliest stages of normal fault development

Ahmed Alghuraybi, Rebecca E. Bell, Chris Jackson

Published: 2021-12-22
Subjects: Earth Sciences, Geology, Tectonics and Structure

Despite decades of study, models for the growth of normal faults lack a temporal framework within which to understand how these structures accumulate displacement and lengthen through time. Here, we use borehole and high-quality 3D seismic reflection data from offshore Norway to quantify the lateral (0.2-1.8 mmyr-1) and vertical (0.004-0.02 mmyr-1) propagation rates (averaged over 12-44 Myr) for [...]

Tectonic controls on geomorphology and spatial distribution of monogenetic volcanoes in the Central Southern Volcanic Zone of the Andes (Argentina)

Fernanda Silva Santos, Carlos Augusto Sommer, Mauricio Barcelos Haag, et al.

Published: 2021-12-16
Subjects: Geology, Geomorphology, Tectonics and Structure, Volcanology

Monogenetic volcanoes are among the most common volcanic landforms on Earth. The morphology and distribution of small volcanoes can provide important information about eruption dynamics and tectonics. The Southern Volcanic Zone of the Andes (CSVZ) comprises one of the most active magmatic regions on Earth. Characterized by the presence of polygenetic volcanoes and calderas in a complex tectonic [...]

Flow regimes during fluid-filled crack propagation in elastic media: Applications to volcanology and magma flow within dykes

Janine Lynsey Kavanagh, Thomas J Jones, David JC Dennis

Published: 2021-12-13
Subjects: Earth Sciences, Fluid Dynamics, Physics, Tectonics and Structure, Volcanology

Scaled analogue experiments were conducted to explore the effect of magma flow regimes, characterised by the Reynolds number (Re), on the transit of magma through the lithosphere via fractures. An elastic, transparent gelatine solid (the crust analogue) was injected by a fluid (magma analogue) to create a thin, vertical, and penny-shaped crack that is analogous to a magma-filled crack (dyke). A [...]

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: 2021-12-10
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 [...]

Improving Urban Seismic Risk Estimates for Bishkek, Kyrgyzstan, Incorporating Recent Geological Knowledge of Hazards

Ruth Amey, John Elliott, C. Scott Watson, et al.

Published: 2021-12-07
Subjects: Geology, Geomorphology, Tectonics and Structure

Many cities are built on or near active faults, which pose seismic hazard and risk to the urban population. This risk is exacerbated by city expansion, which may obscure signs of active faulting. Here we estimate the risk to Bishkek city, Kyrgyzstan, due to realistic earthquake scenarios based on historic earthquakes in the region and improved knowledge of the active faulting. We use previous [...]

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 [...]

Rare allanite in granulitised eclogites constrains timing of eclogite to granulite facies transition in the Bhutan Himalaya

Eleni Wood, Clare Warren, Nick M. W. Roberts, et al.

Published: 2021-11-15
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure

During continental collision, crustal rocks are buried, deformed, transformed and exhumed. The rates, timescales and tectonic implications of these processes are determined by linking geochemical, geochronological and microstructural data from metamorphic rock-forming and accessory minerals. Exposures of lower orogenic crust provide important insights into orogenic evolution, but are rare in [...]

Reproducibility in subsurface geoscience

Michael J. Steventon, Chris Jackson, Mark Ireland, et al.

Published: 2021-10-26
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Environmental Education, Environmental Health and Protection, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Mineral Physics, Natural Resource Economics, Natural Resources and Conservation, Natural Resources Management and Policy, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Paleobiology, Paleontology, Sedimentology, Soil Science, Speleology, Stratigraphy, Sustainability, Tectonics and Structure, Volcanology, Water Resource Management

Reproducibility, the extent to which consistent results are obtained when an experiment or study is repeated, sits at the foundation of science. The aim of this process is to produce robust findings and knowledge, with reproducibility being the screening tool to benchmark how well we are implementing the scientific method. However, the re-examination of results from many disciplines has caused [...]

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 [...]

Fluid-driven Cyclic Reorganisation in Shallow Basaltic Fault Zones

Bob Bamberg, Richard Walker, Marc Reichow, et al.

Published: 2021-10-06
Subjects: Earth Sciences, Tectonics and Structure

Faults represent a critical heterogeneity in basaltic sequences, yet their architectural and hydromechanical evolution is poorly constrained. We present a detailed multi-scale characterisation of passively exhumed fault zones from the layered basalts of the Faroe Islands, which reveals cyclic stages of fault evolution. Outcrop-scale structures and fault rock distribution within the fault zones [...]

The Effects of Layer Thickness on Brittle Boudinage in 3D

Bob Bamberg, Christoph von Hagke, Simon Virgo, et al.

Published: 2021-10-01
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

We analyse the effects of thickness on brittle boudinage in a metre-scale sample of marble containing a layer of amphibolite recording two phases of ductile pinch-and-swell followed by five generations of brittle boudinage. The amphibolite geometry was reconstructed in 3D, employing a method we call ‘outcrop-scale tomography’. Our data suggests that strain localisation depends on the ration of [...]


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