Preprints
Filtering by Subject: Geophysics and Seismology
Numerical wave propagation through ice-covered regions
Published: 2019-03-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In recent years, seismic station coverage in polar regions has been increasing steadily, providing new insight into the deep structure and dynamics of these remote parts of the globe. Numerical seismic wave propagation through polar regions is complicated by the presence of ice sheets. At periods relevant for regional-scale waveform tomography, the ice acts as a thin layer that, for an exact [...]
Poroelastic effects destabilize mildly rate-strengthening friction to generate stable slow slip pulses
Published: 2019-03-18
Subjects: Applied Mechanics, Earth Sciences, Engineering, Geology, Geophysics and Seismology, Mechanical Engineering, Physical Sciences and Mathematics, Physics, Statistical, Nonlinear, and Soft Matter Physics, Tribology
Slow slip events on tectonic faults, sliding instabilities that never accelerate to inertially limited ruptures or earthquakes, are one of the most enigmatic phenomena in frictional sliding. While observations of slow slip events continue to mount, a plausible mechanism that permits instability while simultaneously limiting slip speed remains elusive. Rate-and-state friction has been successful [...]
The Dynamics of Elongated Earthquake Ruptures
Published: 2019-03-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The largest earthquakes propagate laterally after saturating the fault’s seismogenic width and reach large length-to-width ratios L/W. Smaller earthquakes can also develop elongated ruptures due to confinement by heterogeneities of initial stresses or material properties. The energetics of such elongated ruptures is radically different from that of conventional circular crack models: they feature [...]
The effect of stress changes on time-dependent earthquake probabilities for the central Wasatch Fault Zone, Utah, USA.
Published: 2019-03-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Static and quasi-static Coulomb stress changes produced by large earthquakes can modify the probability of occurrence of subsequent events on neighboring faults. This approach is based on physical (Coulomb stress changes) and statistical (probability calculations) models, which are influenced by the quality and quantity of data available in the study region. Here, we focus on the Wasatch Fault [...]
Post-critical SsPmp and its Applications to Virtual Deep Seismic Sounding 2: 1D Imaging of the Crust/Mantle and Joint Constraints with Receiver Function
Published: 2019-03-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Virtual Deep Seismic Sounding (VDSS) has recently emerged as a novel method to image the crust-mantle-boundary (CMB) and potentially other lithospheric boundaries. In Liu et al., 2018 (“Part 1”), we showed that the arrival time and waveform of post-critical SsPmp, the post-critical reflection phase at the CMB used in VDSS, is sensitive to multiple attributes of the crust and upper mantle. Here, [...]
A secondary zone of uplift due to megathrust earthquakes
Published: 2019-03-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The 1960 M9.5 Valdivia and 1964 M9.2 Alaska earthquakes caused a decimeters-high secondary zone of uplift a few hundred kilometers landward of the trench. We analyze GPS data from the 2010 M8.8 Maule and 2011 M9.0 Tohoku-Oki earthquakes to confirm the existence of a secondary zone of uplift due to great earthquakes at the megathrust interface. This uplift varies in magnitude and location, but [...]
Machine Learning Reveals the State of Intermittent Frictional Dynamics in a Sheared Granular Fault
Published: 2019-03-05
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Geotechnical Engineering, Physical Sciences and Mathematics
The seismogenic plate boundaries are presumed to behave similarly to a densely packed granular medium, where fault and blocks systems rapidly rearrange the distribution of forces within themselves, as particles do in slowly sheared granular systems. We use machine learning and show that statistical features of velocity signals from individual particles in a simulated sheared granular fault [...]
The 2018-2019 seismo-volcanic crisis east of Mayotte, Comoros islands: seismicity and ground deformation markers of an exceptional submarine eruption
Published: 2019-02-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
On May 10th, 2018, an unprecedented long and intense seismic crisis started offshore, east of Mayotte, the easternmost of the Comoros volcanic islands. The population felt hundreds of events. Over the course of one year, 32 earthquakes with magnitude greater than 5 occurred, including the largest event ever recorded in the Comoros (Mw = 5.9 on May 15th, 2018). Earthquakes are clustered in space [...]
Dynamics of the lithosphere and upper mantle in light of seismic anisotropy
Published: 2019-02-23
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic anisotropy records continental dynamics in the crust and convective deformation in the mantle. Deciphering this archive holds huge promise for our understanding of the thermo-chemical evolution of our planet, but doing so is complicated by incomplete imaging and non-unique interpretations. Here, we focus on the upper mantle and review seismological and laboratory constraints as well as [...]
RSFit3000: A MATLAB GUI-Based Program for Determining Rate and State Frictional Parameters from Experimental Data
Published: 2019-02-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a MATLAB, graphical user interface (GUI) software package for analyzing rate and state friction experiments. Called RSFit3000, the software allows users to easily constrain frictional parameters by fitting velocity step and slide-hold-slide events using the aging and slip law forms for state variable evolution. RSFit3000 includes features for removing strain hardening/weakening trends [...]
Can a Raspberry Shake Seismic Network Complement a National Seismic Network? A case study in Haiti
Published: 2019-02-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Complex networks of high-tech sensors are tough to operate and maintain in developing countries – but new low-costs, low-maintenance instruments may help. Because they are “connected objects” they also provide new opportunities to engage the civil society in citizen-science. Here we describe a seismological instrumentation experiment in Haiti with sensors that cost less than 500$ and can be [...]
Technical note on the multi-GNSS, multi-frequency and near real-time ionospheric TEC monitoring system for South America
Published: 2019-02-21
Subjects: Atmospheric Sciences, Earth Sciences, Geophysics and Seismology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Development of regional services able to provide ionospheric total electron content (TEC) maps with a high spatial resolution, and in near real-time, are of high importance for applications and the research community. We provide here the methodologies, and a preliminary assessment, of such a system. The system relies on the public Global Navigational Satellite Systems (GNSS) infrastructure in [...]
Deep Learning Application for 4D Pressure Saturation Inversion Compared to Bayesian Inversion on North Sea Data
Published: 2019-02-21
Subjects: Applied Statistics, Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Statistics and Probability
In this work we present a deep neural network inversion on map-based 4D seismic data for pressure and saturation. We present a novel neural network architecture that trains on synthetic data and provides insights into observed field seismic. The network explicitly includes AVO gradient calculation within the network as physical knowledge to stabilize pressure and saturation changes separation. [...]
Bayesian Dynamic Finite-Fault Inversion: 2. Application to the 2016 Mw6.2 Amatrice, Italy, Earthquake
Published: 2019-02-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In 2016 Central Italy was struck by a sequence of three normal faulting earthquakes with moment magnitude (Mw) larger than 6. The Mw 6.2 Amatrice event (08/24) was the first one, causing building collapse and about 300 casualties. The event was recorded by a uniquely dense network of seismic stations. Here we perform its dynamic source inversion to infer the fault friction parameters and stress [...]
Coupled, Physics-based Modeling Reveals Earthquake Displacements are Critical to the 2018 Palu, Sulawesi Tsunami
Published: 2019-02-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The September 2018, Mw 7.5 Sulawesi earthquake occurring on the Palu-Koro strike-slip fault system was followed by an unexpected localized tsunami. We show that direct earthquake-induced uplift and subsidence could have sourced the observed tsunami within Palu Bay. To this end, we use a physics-based, coupled earthquake-tsunami modeling framework tightly constrained by observations. The model [...]