Preprints
Filtering by Subject: Geophysics and Seismology
The moment duration scaling relation for slow rupture arises from transient rupture speeds
Published: 2019-07-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The relation between seismic moment and earthquake duration for slow rupture follows a different power law exponent than sub-shear rupture. The origin of this difference in exponents remains unclear. Here, we introduce a minimal one-dimensional Burridge-Knopoff model which contains slow, sub-shear and super-shear rupture, and demonstrate that different power law exponents occur because the [...]
Influence of fault roughness on surface displacement: from numerical simulations to coseismic slip distributions
Published: 2019-07-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Field studies characterized early on natural faults as rough, i.e. non-planar at all scales. Fault roughness induces local stress perturbations, which dramatically affect rupture behavior, resulting in slip heterogeneity. The relation between fault roughness and produced slip remains, however, a key knowledge gap in current numerical and field studies. In this study, we analyze numerical [...]
Seismological evidence for subcrustal magmatic injection beneath Fogo volcano, Cape Verde hotspot
Published: 2019-07-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Fogo volcano belongs to the Cape Verde hotspot and its most recent eruption occurred from November 2014 to February 2015. From January to December 2016 we operated a temporary seismic network on Fogo and were able to locate 289 earthquakes in total. While most of the events occur at distances > 25 km near the neighboring island of Brava. However, on 15th August 2016 we recorded an isolated [...]
Photonic seismology in Monterey Bay: Dark fiber DAS illuminates offshore faults and coastal ocean dynamics
Published: 2019-07-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Emerging fiber-optic sensing technology coupled to existing subsea telecommunications cables can provide access to unprecedented seafloor observations of both ocean and solid earth phenomena. During March 2018, we conducted a Distributed Acoustic Sensing (DAS) measurement campaign along a buried fiber-optic cable typically used for data transfer to and from a scientific cabled observatory [...]
Denoising ambient seismic field correlation functions with convolutional autoencoders
Published: 2019-07-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic interferomestry is an established method for monitoring the temporal evolution of the Earths physical properties. We introduce a new technique to improve the precision and temporal resolution of seismic monitoring studies based on deep learning. Our method uses a convolutional denoising autoencoder, called ConvDeNoise, to denoise ambient seismic field correlation functions. The technique [...]
Segmentation of the Main Himalayan Thrust inferred from geodetic observations of interseismic coupling
Published: 2019-07-05
Subjects: Computer Sciences, Earth Sciences, Environmental Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Probability, Statistics and Probability, Tectonics and Structure
Mapping the distribution of locked segments along subduction megathrusts is essential for improving quantitative assessments of seismic hazard. Previous geodetic studies suggest the Main Himalayan Thrust (MHT) is homogeneously locked (or coupled) along its complete length over a down-dip extent of ~100 km. However, an increasing number of seismological and geophysical observations suggests the [...]
Pervasive foreshock activity across southern California
Published: 2019-06-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Foreshocks have been documented as preceding less than half of all mainshock earthquakes. These observations are difficult to reconcile with laboratory earthquake experiments and theoretical models of earthquake nucleation, which both suggest that foreshock activity should be nearly ubiquitous. Here we use a state-of-the-art, high-resolution earthquake catalog to study foreshock sequences of [...]
Are magnetic stripes on the Cuvier Abyssal Plain (offshore NW Australia) diagnostic of oceanic crust?
Published: 2019-06-22
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Magnetic stripes have long been used to define the presence and age of oceanic crust. However, continental crust heavily intruded by magma can record magnetic reversals akin to those observed in oceanic crust. We re-evaluate the nature of the Cuvier Abyssal Plain (CAP), offshore NW Australia, which hosts magnetic stripes and has previously been defined as oceanic crust. We use magnetic, 2D [...]
Comments on the paper “Two independent real-time precursors of the 7.8 M earthquake in Ecuador based on radioactive and geodetic processes – Powerful tools for an early warning system” by Toulkeridis et al. (2019)
Published: 2019-06-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In the paper entitled “Two independent real-time precursors of the 7.8 M earthquake in Ecuador based on radioactive and geodetic processes – Powerful tools for an early warning system”, Toulkeridis et al. (2019) claim that they found radiation and GPS signal anomalies before the April 16th 2016 Pedernales earthquake (Ecuador) and that their findings can be used to forecast earthquakes in the [...]
Gravitational field calculation in spherical coordinates using variable densities in depth
Published: 2019-06-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a new methodology to compute the gravitational fields generated by tesseroids (spherical prisms) whose density varies with depth according to an arbitrary continuous function. It approximates the gravitational fields through the Gauss-Legendre Quadrature along with two discretization algorithms that automatically control its accuracy by adaptively dividing the tesseroid into smaller [...]
Areal parameter estimates from multiple datasets
Published: 2019-06-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A wide range of methods exist for interpolation between spatially distributed points drawn from a single population. Yet often multiple datasets are available with differing distribution, character and reliability. A simple scheme is introduced to allow the fusion of multiple datasets. Each dataset is assigned an a priori spatial influence zone around each point and a relative weight based on its [...]
Distributed sensing of earthquakes and ocean-solid Earth interactions on seafloor telecom cables
Published: 2019-06-07
Subjects: Earth Sciences, Environmental Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions. The potential to leverage the existing fiber optic seafloor telecom cables that criss-cross the oceans, by turning them into dense arrays of seismo-acoustic sensors, remains to be evaluated. Here, we [...]
Physically consistent modeling of dike induced deformation and seismicity: Application to the 2014 Bárðarbunga dike, Iceland
Published: 2019-06-03
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Dike intrusions are often associated with surface deformation and propagating swarms of earthquakes. These are understood to be manifestations of the same underlying physical process, although rarely modeled as such. We construct a physics-based model of the 2014 B\ar{\dh}arbunga dike, by far the best observed large dike ($> 0.5$ km$^3$) to date. We constrain the background stress state [...]
The 2007 Caldera Collapse of Piton de la Fournaise Volcano: Source Process from Very-Long-Period Seismic Signals
Published: 2019-06-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In April 2007, Piton de la Fournaise volcano experienced its largest caldera collapse in at least 300 years. This event consisted of a series of 48 subsidence increments characterized by very-long-period (VLP) seismic signals equivalent to Mw 4.4 to 5.4. Source analysis of VLP events suggests a piston-like mechanism with a collapsing crack source corresponding to the contraction of the magma [...]
A shallow earthquake swarm close to hydrocarbon activities: discriminating between natural and induced causes for the 2018–19 Surrey, UK earthquake sequence
Published: 2019-05-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes induced by subsurface industrial activities are a globally emotive issue, with a growing catalogue of induced earthquake sequences. However, attempts at discriminating between natural and induced causes, particularly for anomalously shallow seismicity, can be challenging. An earthquake swarm during 2018–19 in south-east England with a maximum magnitude of ML 3.2 received great public [...]