Preprints
Filtering by Subject: Geophysics and Seismology
Stress, rigidity and sediment strength control megathrust earthquake and tsunami dynamics
Published: 2020-08-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Megathrust faults host the largest earthquakes on Earth which can trigger cascading hazards such as devastating tsunamis. Determining characteristics that control subduction zone earthquake and tsunami dynamics is critical to mitigate megathrust hazards, but is impeded by structural complexity, large spatio-temporal scales, and scarce or asymmetric instrumental coverage. Here we use [...]
A Source Clustering Approach for Efficient Inundation Modeling and Regional Scale PTHA
Published: 2020-08-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
For coastal regions on the margin of a subduction zone, near-field megathrust earthquakes are the source of the most extreme tsunami hazards, and are important to handle properly as one aspect of any Probabilistic Tsunami Hazard Assessment (PTHA). Typically, great variability in inundation depth at any point is possible due to the extreme variation in extent and pattern of slip over the fault [...]
Isotropic and Azimuthally Anisotropic Rayleigh Wave Dispersion Across the Juan de Fuca and Gorda Plates and U.S. Cascadia from Earthquake Data and Ambient Noise Two- and Three-Station Interferometry
Published: 2020-08-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
We use data from the Cascadia Initiative (CI) amphibious array and the USArray Transportable Array to construct and compare Rayleigh wave isotropic and azimuthally anisotropic phase speed maps across the Juan de Fuca and Gorda Plates extending onto the continental north- western United States. Results from both earthquakes (28–80 s) as well as ambient noise two- and three-station interferometry [...]
Principal component analysis of seismic facies
Published: 2020-08-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic facies analyses are fundamental to the study of sedimentary, tectonic and magmatic systems using seismic reflection data. These analyses generally assume that seismic facies are: (1) well defined, (2) distinct and (3) prevalent patterns in the data. Here, we examine these assumptions critically. First, we demonstrate how to extract the main seismic facies from conventional industry [...]
Seismic diffraction imaging to better characterise mass-transport complexes: examples from the Gulf of Cadiz, south west Iberian Margin
Published: 2020-08-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Mass‐transport complexes (MTCs) are often characterised by small‐scale, discontinuous internal structure, such as slide blocks, rough interfaces, faults and truncated strata. Seismic images may not properly resolve such structure because seismic reflections are fundamentally limited in lateral resolution by the source bandwidth. The relatively weak seismic diffractions, instead, encode [...]
Notes on Seismic Source Models in Elastostatics
Published: 2020-07-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic source models in elastostatics lay the foundations for the popular earthquake deformation formula derived in Okada (1992), which forms key components for many studies in earthquake displacement simulations, earthquake source inversions and ground-motion predictions. However,despite of their importance, we found that the assumptions and proofs of some important theorems about the topic are [...]
Inferring Interseismic Coupling along the Lesser Antilles Arc: a Bayesian Approach
Published: 2020-07-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The Lesser Antilles subduction zone is a challenging region when it comes to unraveling its seismogenic behavior. Over the last century, the subduction megathrust has been seismically quiet, with no large thrust event recorded, which raises the question whether this subduction zone is able to produce large interplate earthquakes or not. However, two historical earthquakes in the 19th century, a M [...]
Robust Q estimation using surface seismic data
Published: 2020-07-30
Subjects: Applied Mathematics, Computational Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Numerical Analysis and Computation, Physical Sciences and Mathematics
Direct wave arrivals are the most robust signals to determine velocity and consequently they have been used for almost a century in hydrocarbon exploration. The reason is simple as the arrivaltime is explicitly available and provide a direct measurement of the average velocity of the sub-surface ray-path. These signals have not been extensively used to estimate attenuation or Q. One reason may [...]
Energetic Rupture and Tsunamigenesis during the 2020 Mw 7.4 La Crucecita, Mexico Earthquake
Published: 2020-07-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The La Crucecita earthquake ruptured on the megathrust generating strong shaking and a modest, long-lived tsunami. This is a significant earthquake that illuminates important aspects of the behavior of the megathrust as well as the potential related hazards. The rupture is contained within 15-30km depth, ground motions are elevated and the energy to moment ratio is high. We argue that it [...]
Whats down there? The structures, materials and environment of deep-seated tremor and slip
Published: 2020-07-16
Subjects: Earth Sciences, Geochemistry, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Episodic tremor and slow slip (ETS) events occur downdip of the seismogenic zone of numerous subduction megathrusts and plate boundary strike-slip faults. These events represent a fascinating and perplexing mode of fault failure that has greatly broadened our view of earthquake dynamics. In this contribution, we review constraints on the ETS deformation process from both geophysical observations [...]
Precursory slow slip and foreshocks on rough faults
Published: 2020-07-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Foreshocks are not uncommon prior to large earthquakes, but their physical mechanism controversial. Two interpretations have been put forward: 1. foreshocks are driven by aseismic nucleation; 2. foreshocks are cascades, with each event triggered by earlier ones. Here we study seismic cycles on faults with fractal roughness at wavelengths exceeding the nucleation length. We perform 2-D [...]
Bayesian inference for fault slip distributions based on ensemble modeling of the uncertainty of underground structure
Published: 2020-07-15
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The prediction errors that originate from the uncertainty of underground structure is often a major contributor of the errors between the data and the model predictions in fault slip estimation using geodetic or seismic waveform data. However, most studies on slip inversions either neglect the model prediction errors or do not distinguish them from observation errors. Several methods that [...]
On the effect of grain fragmentation on frictional instabilities in faults with granular gouge
Published: 2020-07-15
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics
The evolution of frictional strength during stick-slip dynamics of a fault system is key to understanding the earthquake nucleation and rupture patterns. In mature faults, granular gouge is produced by wear, comminution or fragmentation during tectonic movements. In this work, we introduce a fragmentation model in the simulation of a sheared granular fault to explore the influence of grain [...]
TRAINING A PHYSICS-GUIDED CONVOLUTIONAL NEURAL NETWORK FOR SEISMIC INVERSION
Published: 2020-07-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The determination of subsurface elastic property models is crucial in quantitative seismic data processing and interpretation. This problem is commonly solved by deterministic physical methods, such as tomography or full waveform inversion (FWI). However, these methods are entirely local, and require accurate initial models. Deep learning represents a plausible class of methods for seismic [...]
Tracking and measuring of clay shrinking and swelling using spaceborne remote sensing
Published: 2020-07-12
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics
New capabilities for measuring and monitoring are needed to improve the shrink/swell hazard. A new French experimental site at Chaingy (Centre-Val de Loire) has been instrumented using extensometers at the surface and soil moisture sensors in the clay layer. Here we show by direct comparison between remote and in situ data for a period longer than three years that the vertical ground [...]