Preprints
Filtering by Subject: Geophysics and Seismology
Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations
Published: 2019-10-16
Subjects: Astrophysics and Astronomy, Earth Sciences, Geophysics and Seismology, Other Astrophysics and Astronomy, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences
A terrestrial planet is molten during formation and may remain molten due to intense insolation or tidal forces. Observations favour the detection and characterisation of hot planets, potentially with large outgassed atmospheres. We aim to determine the radius of hot Earth-like planets with large outgassing atmospheres. Our goal is to explore the differences between molten and solid silicate [...]
The 2018 Fiji Mw 8.2 and 7.9 deep earthquakes: one doublet in two slabs
Published: 2019-10-13
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The cold Fiji-Tonga subduction zone accounts for >75% of cataloged deep earthquakes but none of the largest ten in the last century. On 19 August 2018 and 06 September 2018, a deep earthquake doublet with moment magnitude (Mw) 8.2 and 7.9 struck the Fiji area, providing a rare opportunity to interrogate the behaviors of great deep earthquakes in cold slabs. By cursory examination, the doublet [...]
Redshift of Earthquakes via Focused Blind Deconvolution of Teleseisms
Published: 2019-10-13
Subjects: Applied Mathematics, Earth Sciences, Electrical and Computer Engineering, Engineering, Geophysics and Seismology, Physical Sciences and Mathematics, Signal Processing
We present a robust factorization of the teleseismic waveforms resulting from an earthquake source into signals that originate from the source and signals that characterize the path effects. The extracted source signals represent the earthquake spectrum and its variation with azimuth. Unlike most prior work on source extraction, our method is data-driven, and it does not depend on any [...]
Making mountains on Earth and beyond
Published: 2019-10-13
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Many of Earth’s mountains are formed in orogenic belts aligned along plate margins. Their altitudes (reaching >8,000 m above sea level in the Himalayas) are the result of the balance between tectonic forces causing their uplift and erosive processes causing their destruction. The tectonic forces result, in part, from isostacy which is determined by the plasticity of the asthenosphere, but [...]
Magnetotelluric multiscale 3-D inversion reveals crustal and upper mantle structure beneath the Hangai and Gobi-Altai region in Mongolia
Published: 2019-10-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Central Mongolia is a prominent region of intracontinental surface deformation and intraplate volcanism. To study these processes, which are poorly understood, we collected magnetotelluric data in the Hangai and Gobi-Altai region in central Mongolia and derived the first three-dimensional (3-D) resistivity model of the crustal and upper mantle structure in this region. The geological and tectonic [...]
Noise-derived broadband full Green functions for a radially layered Earth
Published: 2019-10-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The emerging noise correlation technique provides a way to approximate the Green function of medium with the correlation function between ambient noise wavefields. It has been recognized that not only the regularly observable seismic phase, but also spurious phases that have no correspondence in real seismograms, are constructed from noise correlations. In this study, we synthesize global noise [...]
Crack to pulse transition and magnitude statistics during earthquake cycles on a self-similar rough fault
Published: 2019-10-08
Subjects: Earth Sciences, Engineering, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Tectonics and Structure, Tribology
Faults in nature demonstrate fluctuations from planarity at most length scales that are relevant for earthquake dynamics. These fluctuations may influence all stages of the seismic cycle; earthquake nucleation, propagation, arrest, and inter-seismic behavior. Here I show quasi-dynamic plane-strain simulations of earthquake cycles on a self-similar and finite 10 km long rough fault with [...]
Metastable olivine wedge beneath the Japan Sea imaged by seismic interferometry
Published: 2019-10-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The metastable olivine wedge (MOW) within subducted slabs has long been hypothesized to host deep-focus earthquakes (>300 km). Its presence would also rule out hydrous slabs being subducted into the mantle transition zone. However, the existence and dimensions of MOW remain controversial. Here, we apply inter-source interferometry, which converts deep earthquakes into virtual seismometers, to [...]
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 [...]