Preprints
Filtering by Subject: Geophysics and Seismology
Creep on seismogenic faults: Insights from analogue earthquake experiments
Published: 2019-05-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Tectonic faults display a range of slip behaviors including continuous and episodic slip covering rates of more than 10 orders of magnitude (m/s). The physical control of such kinematic observations remains ambiguous. To gain insight into the slip behavior of brittle faults we performed laboratory stick-slip experiments using a rock analogue, granular material. We realized conditions under which [...]
Teleseisms and Microseisms on an Ocean-Bottom Distributed Acoustic Sensing Array
Published: 2019-05-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Sparse seismic instrumentation in the oceans limits our understanding of deep Earth dynamics and submarine earthquakes. Distributed acoustic sensing (DAS), an emerging technology that converts optical fiber to seismic sensors, allows us to leverage pre-existing submarine telecommunication cables for seismic monitoring. Here we report observations of microseism, local surface gravity waves, and a [...]
Shallow slow slip events along the Nankai Trough detected by the GNSS-A
Published: 2019-05-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Various slow earthquakes (SEQs), including tremors, very-low-frequency events, and slow slip events (SSEs), occur along megathrust zones. In a shallow plate boundary region, although many SEQs have been observed along pan-Pacific subduction zones, SSEs with a duration on the order of a year or with a large slip have not yet been detected due to difficulty in offshore observation. We try to [...]
A Novel Hybrid Finite Element-Spectral Boundary Integral Scheme for Modeling Earthquake Cycles: Application to Rate and State Faults with Low-Velocity Zones
Published: 2019-05-14
Subjects: Applied Mechanics, Earth Sciences, Engineering, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics
We present a novel hybrid finite element (FE) - spectral boundary integral (SBI) scheme that enables efficient simulation of earthquake cycles. This combined FE-SBI approach captures the benefits of finite elements in modelling problems with nonlinearities, as well as the computational superiority of SBI. The domain truncation enabled by this scheme allows us to utilize high-resolution finite [...]
Complex earthquake behavior on simple faults
Published: 2019-05-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
While power-law distributions in seismic moment and interevent times are ubiquitous in regional catalogs, the statistics of individual faults remains controversial. Continuum fault models typically produce characteristic earthquakes or a narrow range of sizes, leading to the view that the regional statistics originates from interaction of multiple faults. I present theoretical arguments and [...]
Growing primordial continental crust self-consistently in global mantle convection models
Published: 2019-05-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The majority of continental crust formed during the hotter Archean was composed of Tonalite-Trondhjemite-Granodiorite (TTG) rocks. In contrast to the present-day loci of crust formation around subduction zones and intra-plate tectonic settings, TTGs are formed when hydrated basalt melts at garnet-amphibolite, granulite or eclogite facies conditions. Generating continental crust requires a two [...]
Probabilistic space- and time-interaction modeling of main-shock earthquake rupture occurrence
Published: 2019-04-28
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Physical Sciences and Mathematics, Statistical Models, Statistics and Probability, Structural Engineering
This paper presents a probabilistic formulation for modeling earthquake rupture processes of mainshocks. A correlated multivariate Bernoulli distribution is used to model rupture occurrence. The model captures time interaction through the use of Brownian passage-time (BPT) distributions to assess rupture interarrival in multiple sections of the fault, and it also considers spatial interaction [...]
Bayesian parameter estimation for space and time interacting earthquake rupture model using historical and physics-based simulated earthquake catalogs
Published: 2019-04-25
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Physical Sciences and Mathematics, Risk Analysis
This paper presents a robust parameter estimation technique for a probabilistic earthquake hazard model that captures time and space interactions between earthquake mainshocks. The approach addresses the existing limitations of parameter estimation techniques by developing a Bayesian formulation and leveraging physics-based simulated synthetic catalogs to expand the limited datasets of historical [...]
Influence of dissolution on frictional properties of carbonate faults
Published: 2019-04-25
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Physical Sciences and Mathematics
Velocity stepping experiments have been performed on a simulated calcite gouge using an annular shear apparatus to investigate the effect of dissolution on the frictional properties of a carbonate fault. The tested material was put in contact with hydrochloric acid at different concentration in order to dissolve the grains. Particle size analysis shows that the small grains tend to disappear due [...]
A physics-based approach of deep interseismic creep for viscoelastic strike-slip earthquake cycle models
Published: 2019-04-24
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Most geodetic inversions of surface deformation rates consider the depth distribution of interseismic fault slip-rate to be time invariant. However, some numerical simulations show down-dip penetration of dynamic rupture into regions with velocity-strengthening friction, with subsequent up-dip propagation of the locked-to-creeping transition. Recently, Bruhat & Segall (2017) developed a new [...]
A Scalable Algorithm for Cross-correlations of Compressed Ambient Seismic Noise
Published: 2019-04-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Companies and academic geophysicists are increasingly collecting continuous seismic data on denser arrays, and are looking to a variety of lossy compression methods to store and quickly access this data. Some researchers turn to ambient noise interferometry for low-cost near-surface imaging to avoid to cost and permitting required for active source experiments, but the computation can be very [...]
Finite frequency inversion of cross-correlation amplitudes for ambient noise source directivity estimation
Published: 2019-04-15
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a new method for determining the azimuthal variation of ambient seismic noise sources, that combines the computational speed and simplicity of traditional approaches with the rigour of waveform-inversion-based approaches to noise-source estimation. This method is based on a previously developed theoretical framework of sensitivity kernels for cross-correlation amplitudes. It performs a [...]
Efficient 3D large-scale forward-modeling and inversion of gravitational fields in spherical coordinates with application to lunar mascons
Published: 2019-04-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
An efficient forward modeling algorithm for calculation of gravitational fields in spherical coordinates is developed for 3D large‐scale gravity inversion problems. 3D Gauss‐Legendre quadrature (GLQ) is used to calculate the gravitational fields of mass distributions discretized into tesseroids. Equivalence relations in the kernel matrix of the forward‐modeling are exploited to decrease storage [...]
Characterising strong force networks produced during granular shear using percolation methods: Revealing the bridge between local grain scale processes and macroscopic sliding
Published: 2019-04-08
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Physics, Tectonics and Structure
Faults, landslides and subglacial till often contain accumulations of granular debris. Their macroscopic motion is at least to some extent determined by the processes operating in this sheared granular material. A valid question in these environments is how the local behaviour at the individual granular contacts actually sums up to influence macroscopic sliding. Laboratory experiments and [...]
Fast non-linear gravity inversion in spherical coordinates with application to the South American Moho
Published: 2019-04-07
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Estimating the relief of the Moho from gravity data is a computationally intensive non-linear inverse problem. What is more, the modeling must take the Earths curvature into account when the study area is of regional scale or greater. We present a regularized non-linear gravity inversion method that has a low computational footprint and employs a spherical Earth approximation. To achieve this, we [...]