Preprints
Filtering by Subject: Geophysics and Seismology
Introduction of covariance components in slip inversion of geodetic data following a non-uniform spatial distribution and application to slip deficit rate estimation in the Nankai Trough subduction zone
Published: 2019-08-02
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
When spatial distribution of observation stations has bias in geodetic slip inversion, modeling errors in the inversion scheme may result in significant unnatural short-wave components in estimated slip distribution, which overfit to data. Combined use of both land and seafloor geodetic data in slip inversion often leads to such situations. To avoid overfitting, I proposed a method to [...]
Fracture and Weakening of Jammed Subduction Shear Zones, Leading to the Generation of Slow Slip Events
Published: 2019-07-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Geodetic data have revealed that parts of subduction interfaces creep steadily or transiently. Transient slow slip events (SSEs) are typically interpreted as aseismic frictional sliding. However, SSEs may also occur via mixed visco‐brittle deformation, as observed in shear zones containing mixtures (mélange) of strong fractured clasts embedded in a weak visco‐brittle matrix. We test the [...]
Basal melting over Subglacial Lake Ellsworth and it catchment: insights from englacial layering
Published: 2019-07-25
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Hydrology, Physical Sciences and Mathematics
Deep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used [...]
Geostatistical characterisation of internal structure of mass-transport deposits from seismic reflection images and borehole logs
Published: 2019-07-24
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic reflection images of mass-transport deposits often show apparently chaotic, disorded or low-reflectivity internal seismic facies. The lack of laterally coherent reflections can prevent horizon-based interpretation of internal structure. This study instead inverts for geostatistical parameters which characterise the internal heterogeneity of mass-transport deposits from depth-domain [...]
Investigating the role of faults in fluid migration and gas hydrate formation along the southern Hikurangi Margin, New Zealand
Published: 2019-07-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The Hikurangi Margin off the east coast of the North Island (Te Ika-a-Māui) is a tectonically active subduction zone and the location of New Zealand’s largest gas hydrate province. Faults are internally complex volumetric zones that may play a significant role in the migration of fluids beneath the seafloor. The combined processes of deformation and fluid migration result in the formation of [...]
Are we in the right path in using early warning systems?
Published: 2019-07-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
This article focusses on the recent tsunami in Indonesia, and the factors led to a large number of fatalities. We also discussed the failure of early warning systems, steps, methods and technologies, in general, to improve the early warning systems in the future to mitigate the loss of lives and property during these impending disasters. This article is timely as Indonesia has seen one of the [...]
Urban Seismic Site Characterization by Fiber-Optic Seismology
Published: 2019-07-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Accurate ground-motion prediction requires detailed site effect assessment, but in urban areas where such assessments are most important, geotechnical surveys are difficult to perform, limiting their availability. Distributed acoustic sensing (DAS) offers an appealing alternative by repurposing existing fiber-optic cables, normally employed for telecommunication, as an array of seismic sensors. [...]
The moment duration scaling relation for slow rupture arises from transient rupture speeds
Published: 2019-07-16
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: 2019-07-10
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: 2019-07-09
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: 2019-07-04
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: 2019-07-04
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 [...]