Preprints
Filtering by Subject: Geophysics and Seismology
Deep Low-Frequency Earthquakes Associated with the Eruptions of Shinmoe-dake in Kirishima Volcanoes
Published: 2019-10-06
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Deep low-frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal the relationship between DLF earthquakes and volcanic activity including eruptions by relocating the hypocenters of the earthquakes using the network correlation coefficient method and detecting the earthquakes comprehensively using the matched [...]
Key controls on hydrocarbon retention and leakage from structural traps in the Hammerfest Basin, SW Barents Sea: implications for prospect analysis and risk assessment
Published: 2019-10-03
Subjects: Analysis, Earth Sciences, Geology, Geophysics and Seismology, Mathematics, Physical Sciences and Mathematics, Tectonics and Structure
Evidence of hydrocarbon leakage has been well documented across the SW Barents Sea and is commonly associated with exhumation in the Cenozoic. However, further study is required to understand what specific mechanism(s) facilitate such leakage, and why this occurs in some locations and not others. We use seismic and well data to quantify fault- and top-seal strength based on mechanical and [...]
The fingerprints of flexure in slab seismicity
Published: 2019-10-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquake moment tensors in east Pacific (ePac) slabs typically show downdip tensional axes (DT), whereas in the west Pacific (wPac) they typically show downdip compressional axes (DC) or have mixed orientations indicative of unbending. Prevailing conceptual models emphasise uniform stress/deformation modes, i.e. bulk stretching or shortening, as the dominant control on intermediate depth [...]
Thermal and magnetic evolution of a crystallizing basal magma ocean in Earths mantle
Published: 2019-10-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences
We present the thermochemical evolution of a downward crystallizing BMO overlying the liquid outer core and probe its capability to dissipate enough power to generate and sustain an early dynamo. A total of 61 out of 112 scenarios for a BMO with imposed, present-day $Q_{BMO}$ values of 15, 18, and 21 TW and $Q_r$ values of 4, 8, and 12 TW fully crystallized during the age of the Earth. Most of [...]
Mechanisms controlling fluid break-up and reconnection during two-phase flow in porous media
Published: 2019-10-01
Subjects: Earth Sciences, Engineering, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics
The use of Darcys law to describe steady-state multiphase flow in porous media has been justified by the assumption that the fluids flow in continuously connected pathways. However, a range of complex interface dynamics have been observed during macroscopically steady-state flow, including intermittent pathway flow where flow pathways periodically disconnect and reconnect. The physical [...]
An introduction to seismic diffraction
Published: 2019-09-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Despite its unique properties the diffracted seismic wavefield is still rarely exploited in common practice. Although the first works on seismic diffraction date back at least as far as the 1950s, a first rigorous theoretical framework for diffraction imaging only evolved decades later and many important questions still remain unanswered until the present day. While this comparably slow [...]
The Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS)
Published: 2019-09-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Numerical simulations of Sequences of Earthquakes and Aseismic Slip (SEAS) have made great progress over the past decades to address important questions in earthquake physics and fault mechanics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between aseismic fault slip, earthquake nucleation, and dynamic rupture; and understanding physical factors [...]
Controls on the development and termination of failed continental rifts: Insights from the crustal structure and rifting style of the North Sea via ambient noise tomography
Published: 2019-09-21
Subjects: Applied Mathematics, Computer Sciences, Earth Sciences, Geophysics and Seismology, Numerical Analysis and Computation, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Probability, Statistics and Probability
The mid to lower crust plays an important role in rift initiation and evolution, particularly when large scale sutures and/or terrane boundaries are present. These inherited features can focus strain or act as inhibitors to extensional deformation. Ancient tectonic features are known to exist beneath the iconic failed rift system of the North Sea making it the ideal location to investigate the [...]
Weak phases production and heat generation controls fault friction during seismic slip
Published: 2019-09-15
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The triggering and magnitude of earthquakes is determined by the friction evolution along faults. Experimental results have revealed a drastic decrease of the friction coefficient for velocities close to the maximum seismic one, independently of the material studied. Due to the extreme loading conditions during seismic slip, many competing physical phenomena are occurring (like mineral [...]
Coseismic or Landslide? The source of the 2018 Palu Tsunami
Published: 2019-09-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
On 28 September, 2018, Indonesia was struck by a MW 7.5 strike-slip earthquake. An unexpected tsunami followed, inundating nearby coastlines leading to extensive damage. Given the traditionally non-tsunamigenic mechanism, it is important to ascertain if the source of the tsunami is indeed from coseismic deformation, or something else, such as shaking induced landsliding. Here we determine the [...]
Bayesian elastic Full-Waveform Inversion using Hamiltonian Monte Carlo
Published: 2019-09-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a proof of concept for Bayesian elastic full-waveform inversion in 2-D. This is based on (1) Hamiltonian Monte Carlo sampling of the posterior distribution, (2) the computation of misfit derivatives using adjoint techniques, and (3) a mass matrix tuning of the Hamiltonian Monte Carlo algorithm that accounts for the different sensitivities of seismic velocities and density. We apply our [...]
Recommended "Best Practices" for Chirp Acquisition and Processing
Published: 2019-09-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
This BOEM report describes details our experience/lessons learned in chirp subbottom data collection and processing.
Investigating global correlations between tsunami, earthquake, and subduction zone characteristics
Published: 2019-09-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Tsunamigenic earthquakes pose a large hazard in subduction zones, but it is currently unclear in which - if any - tectonic setting they preferentially occur. Here, we compile the global Subduction Nature & Interconnected Tsunamigenic earthquake Characteristics (SNITCH) database with parameters on subduction geometry and tectonics, megathrust seismicity, and tsunami characteristics of tsunamis [...]
Methods and Test Cases for Linking Physics-Based Earthquake and Tsunami Models
Published: 2019-09-06
Subjects: Computer Sciences, Earth Sciences, Geology, Geophysics and Seismology, Other Computer Sciences, Physical Sciences and Mathematics
Despite the inter-dependence of long term deformation, earthquakes and tsunamis, few modelling approaches bridge these processes. To advance the understanding of tsunami generation and earthquake-tsunami interactions, we present new methods for linking physics-based models of subduction zone geodynamics and seismic cycling, three-dimensional dynamic earthquake rupture, and tsunami generation, [...]
The 1987 to 2019 Tennant Creek, Australia, earthquake sequence: a protracted intraplate multi-mainshock sequence
Published: 2019-09-06
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The 1987 to 2019 Tennant Creek earthquake sequence comprises three 1988 surface-rupturing mainshocks (moment magnitude (Mw 6.2, 6.3, and 6.5) that occurred within a 12-hour period, a preceding foreshock sequence commencing in 1987, and a prolonged aftershock sequence including a Mw 5.0 earthquake on the 1st August 2019. Each surface rupturing event produced a distinct scarp; the south-dipping [...]