Preprints

Filtering by Subject: Geophysics and Seismology

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, Alberto Tomás Caselli, Thiago Ribas Moncinhatto, Gelvam André Hartmann, Michael Ort, Wilbor Poletti, Ricardo Ivan Ferreira da Trindade

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, Aksel Haukanes

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, Stuart A Weinstein, Andi E Sakya

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 normal fault growth using numerical models of continental extension

Sophie Pan, John Naliboff, Rebecca E. Bell, Chris Jackson

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 of appropriate scale, particularly over intermediate timescales (10^4-10^6 yrs). Using 3D numerical simulations of continental [...]

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

Blaž Vičič, Seyyedmaalek Momeni, Alessandra Borghi, Anthony Lomax, Abdelkrim Aoudia

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

The 2019-2020 Indios, Puerto Rico earthquake sequence ruptured on 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 of the deep lithosphere between Pamir and Tarim

Wasja Bloch, Bernd Schurr, Xiaohui Yuan, Lothar Ratschbacher, Sanaa Reuter, Sofia‑Katerina Kufner, Qiang Xu, Junmeng Zhao

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

The Pamir orogen protrudes $\sim$300-km between the Tajik and Tarim lithosphere of central Asia. It is debated, whether its salient location and shape is controlled by indentation of a promontory of Indian mantle lithosphere or by rollback of thinned Tarim--Tajik-basin lithosphere. We present a new local-seismicity and focal-mechanism catalog and a P-wave velocity model [...]

Microstructural differences between naturally-deposited and laboratory beach sands

Amy Ferrick, Vashan Wright, Michael Manga, Nicholas Sitar

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, Sanne Cottaar

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, Svein Mykkeltveit

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 [...]

Imaging the seismic velocity structure of the crust and upper mantle in the northern East African Rift using Rayleigh wave tomography

Emma Louise Chambers, Nicholas Harmon, Catherine Rychert, Ryan Gallacher, Derek Keir

Published: 2021-04-13
Subjects: Geophysics and Seismology

Within the northern East African Rift, multiple seismic models have been produced to understand the evolution of magmatism, however variations in method, resolution, and scale make direct comparisons challenging. The lack of instrumentation off rift further limits our understanding of the spatial extent of tectonic and magmatic processes, which is crucial to understanding magmatic continental [...]

Orbital, the Box - An interactive educational tool for in-depth understanding of astronomical climate forcing.

Bryan C. Lougheed

Published: 2021-04-07
Subjects: Adult and Continuing Education, Astrophysics and Astronomy, Climate, Earth Sciences, Education, Educational Methods, Geology, Geophysics and Seismology, Higher Education, Instructional Media Design, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, The Sun and the Solar System

“Orbital, the Box” provides an interactive tool with graphical user interface (GUI) for stimulating active, visual learning for understanding of astronomical climate forcing. This cross-platform tool can be run locally on a personal computer using a standard web browser environment with no need for plugins, thus maximising accessibility for students and teachers alike. The tool facilitates in the [...]

Coulomb Threshold Rate-and-State Model for Fault Reactivation: Application to induced seismicity at Groningen

Elias Rafn Heimisson, Jonathan D Smith, Jean-Philippe Avouac, Stephen Bourne

Published: 2021-04-06
Subjects: Environmental Monitoring, Geophysics and Seismology, Tectonics and Structure

A number of recent modeling studies of induced seismicity have used the rate-and-state friction model of Dieterich (1994) to account for the fact that earthquake nucleation is not instantaneous. Notably, the model assumes a population of seismic sources accelerating towards instability with a distribution of intial slip speeds such that they would produce earthquakes steadily in absence of any [...]

Dilatancy and compaction of a rate-and-state fault in a poroelastic medium: Linearized stability analysis

Elias Rafn Heimisson, John Rudnicki, Nadia Lapusta

Published: 2021-04-06
Subjects: Applied Mathematics, Geophysics and Seismology, Tectonics and Structure

Faults in the crust at seismogenic depths are embedded in a fluid-saturated, elastic, porous material. Slip on such faults may induce transient pore pressure changes through dilatancy or compaction of the gouge or host rock. However, the poroelastic nature of the crust and the full coupling of inelastic gouge processes and the host rock have been largely neglected in previous analyses. Here, we [...]

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