Preprints

Filtering by Subject: Geophysics and Seismology

The effect of temperature-dependent material properties on simple thermal models of subduction zones

Iris van Zelst, Cedric Thieulot, Timothy J Craig

Published: 2021-06-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

To a large extent, the thermal structure of a subduction zone determines where seismicity occurs through the transition from brittle to ductile deformation and the depth of dehydration reactions. Thermal models of subduction zones can help understand this seismicity by accurate modelling of the thermal structure of the subduction zone. Here, we assess a common simplification in thermal models of [...]

Inferring rheology and geometry of subsurface structures by adjoint-based inversion of principal stress directions

Georg S Reuber, Lukas Holbach, Anton A. Popov, et al.

Published: 2021-05-21
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure

Imaging subsurface structures, such as salt domes, magma reservoirs, or subducting plates, is a major challenge in geophysics. Seismic imaging methods are, so far, the most precise methods to open a window into the Earth. However, the methods may not yield the exact depth or size of the imaged feature and may become distorted by phenomena such as seismic anisotropy, fluid flow, or compositional [...]

Tectonostratigraphy of the northern Okavango Delta and Rift Zone, Botswana

Vashan Wright, Juan Pablo Canales, Nicole de'Enremont, et al.

Published: 2021-05-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

The Okavango Rift Zone (ORZ) and Okavango Delta in Northwest Botswana are Earth’s youngest continental rift system and largest inland delta. The delta and its underlying sediments record the effects of incipient rifting on the geomorphology and stratigraphy within the (incipient) southwestern arm of the East African Rift System in Botswana. Three open questions that we use river-borne [...]

Automatic seismic swarm analyzer system based on template matching algorithms and Master-Cluster relative location methods

Eduardo Andres Diaz Suarez, Itahiza Dominguez Cerdeña, Carmen Del Fresno

Published: 2021-05-19
Subjects: Geophysics and Seismology

Seismic swarms may have periods of intense activity with a high number of earthquakes per hour, with overlapping events and/or low signal-to-noise ratio seismic records. During these intervals, the manual characterization of the activity can become very complex to perform by seismic or volcanic observatories, resulting in inhomogeneous seismic catalogs. In order to tackle this problem, we have [...]

AMS and rock magnetism in the Caviahue-Copahue Volcanic Complex (Southern Andes): emission center, flow dynamics, and implications to the emplacement of non-welded PDCs

Mauricio Barcelos Haag, Carlos Augusto Sommer, Jairo Fransciso Savian, et al.

Published: 2021-05-14
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology

Pyroclastic deposits can cover significant areas and register major geological events. Despite their importance, understanding depositional dynamics of pyroclastic density currents (PDCs) and linking explosive deposits to their emission centers is still a challenge, especially in the case of non-welded, massive ignimbrites. Located in the Southern Andes, the Caviahue Copahue Volcanic Complex [...]

Distributed Acoustic Sensing for Near Surface Imaging from Submarine Telecommunication Cable: Case Study in the Trondheim Fjord

Kittinat Taweesintananon, Martin Landrø, Jan Kristoffer Brenne, et al.

Published: 2021-05-13
Subjects: Geophysics and Seismology, Geotechnical Engineering, Signal Processing, Systems and Communications

Distributed acoustic sensing (DAS) transforms submarine telecommunication cables into densely sampled seismic receivers. To demonstrate DAS applications for seismic imaging, we use an optical cable on the seafloor in the Trondheim Fjord, Norway, to record seismic data generated by a controlled seismic source. The data are simultaneously recorded by a towed hydrophone array and the fiber optic [...]

Multiple imputation via chained equations for elastic welllog imputation and prediction

Antony Hallam, Debajoy Mukherjee, Romain Chassagne

Published: 2021-05-13
Subjects: Geophysics and Seismology

Well logging is an essential component in the petroleum industry for developing a proper understanding of the subsurface geology and formation conditions. Unfortunately, the measurements are rarely complete and missing data intervals are common due to operational issues or malfunction of the logging device. Therefore the imputation of missing data from down-hole well logs is a common problem in [...]

A numerical study of SMART Cables potential in marine hazard early warning for the Sumatra and Java regions

Amir Salaree, Bruce M Howe, Yihe Huang, et al.

Published: 2021-05-04
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences

We present results from a series of exploratory numerical experiments based on ocean bottom pressure and seismic data from a simulated linear array of SMART cable stations off the trench in the Sumatra-Java region. We use six rupture scenarios to calculate tsunami propagation using hydrodynamic simulations. Through these experiments we show that such an addition would result in up to several [...]

Bridging spatiotemporal scales of fault growth during continental extension

Sophie Pan, John Naliboff, Rebecca E. Bell, et al.

Published: 2021-04-21
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Continental extension is accommodated by the development of kilometre-scale normal faults, which grow by accumulating metre-scale earthquake slip over millions of years. Reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data with spatiotemporal scales that span the relatively short-term earthquake cycle, and the longer-term paleoseismic record. Using [...]

The 2019-2020 Southwest Puerto Rico earthquake sequence: seismicity and faulting

Blaž Vičič, Seyyedmaalek Momeni, Alessandra Borghi, et al.

Published: 2021-04-20
Subjects: Geophysics and Seismology, Tectonics and Structure

The 2019-2020 Southwest Puerto Rico earthquake sequence ruptured multiple faults with several moderate magnitude earthquakes. Here we investigate the seismotectonics of this fault system using high precision hypocenter relocation and inversion of the near-field strong motions of five largest events in the sequence (5.6≤Mw≤6.4) for kinematic rupture models. The Mw6.4 mainshock occurred on an NE [...]

The Mid-Lithospheric Discontinuity caused by channel flow in the cratonic lithosphere

Haibin Yang, Irina Artemieva, Hans Thybo

Published: 2021-04-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

Stable cratons with a thick (> 200 km) and cold lithosphere form rheologically strong plates that move atop a ductile asthenospheric mantle. Various types of seismic observations show the presence of a potentially rheologically weak zone at depths of ca. 80 – 150 km termed the Mid-Lithosphere Discontinuity (MLD). While various mechanisms may explain the MLD, the dynamic processes leading to the [...]

Structure and stress field of the lithosphere between Pamir and Tarim

Wasja Bloch, Bernd Schurr, Xiaohui Yuan, et al.

Published: 2021-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

The Pamir plateau protrudes ~300km between the Tajik- and Tarim-basin lithosphere of Central Asia. Whether its salient location and shape are caused by forceful indentation of a promontory of Indian mantle lithosphere is debated. We present a new local-seismicity and focal-mechanism catalog, and a P-wave velocity model of the eastern part of the collision system. The data suggest a south-dipping [...]

Microstructural differences between naturally-deposited and laboratory beach sands

Amy Ferrick, Vashan Wright, Michael Manga, et al.

Published: 2021-04-14
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Geotechnical Engineering, Physical Sciences and Mathematics, Sedimentology

The orientation of and contacts between grains of sand reflect the processes that deposit the sands. Grain orientation and contact geometry also influence mechanical properties. Quantifying and understanding sand microstructure thus provide an opportunity to understand depositional processes better and connect microstructure and macroscopic properties. We compare naturally-deposited beach sands [...]

The morphology, evolution and seismic visibility of partial melt at the core-mantle boundary: Implications for ULVZs

Juliane Dannberg, Robert Myhill, Rene Gassmoeller, et al.

Published: 2021-04-14
Subjects: Geophysics and Seismology

Seismic observations indicate that the lowermost mantle above the core-mantle boundary is strongly heterogeneous. Body waves reveal a variety of ultra-low velocity zones (ULVZs), which extend not more than 100 km above the core-mantle boundary and have shear velocity reductions of up to 30%. While the nature and origin of these ULVZs remain uncertain, some have suggested they are evidence of [...]

Probing the DPRK nuclear test-site down to low seismic magnitude

Steven John Gibbons, Tormod Kværna, Sven Peter Näsholm, et al.

Published: 2021-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

On 3 September 2017, the Democratic People’s Republic of Korea (DPRK) carried out its sixth declared underground nuclear test (NK6) at the Punggye‐ri test site. With body‐wave magnitude 6.1, this explosion was significantly larger than any of the previous five explosions, and it has been followed by numerous smaller seismic events. The explosion generated seismic waves dominated by significantly [...]

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