Preprints
Search for earthquake (504 results)
Stress drop variation of deep-focus earthquakes based on empirical Greens function
Published: 2020-03-04
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We analyze source characteristics of global, deep-focus (> 350 km) earthquakes with moment magnitudes (Mw) larger than 6.0-8.2 using teleseismic P-wave and S-wave spectra and an empirical Greens functions approach. We estimate the corner frequency assuming Brunes source model and calculate stress drops assuming a circular crack model. Based on P-wave and S-wave spectra, the one-standard [...]
Dynamic fault interaction during a fluid-injection induced earthquake: The 2017 Mw 5.5 Pohang event
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics
The November 15th, 2017 Mw 5.5 Pohang earthquake (South Korea) has been linked to hydraulic stimulation and fluid injections, making this the largest induced seismic event associated with an Enhanced Geothermal System (EGS). To understand its source dynamics and fault interactions, we conduct the first 3D high-resolution spontaneous dynamic rupture simulations of an induced earthquake. We account [...]
Effect of fault damage zones on long-term earthquake behavior on mature strike-slip faults
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Mature strike-slip faults are usually surrounded by a narrow zone of damaged rocks characterized by low seismic wave velocities. Observations of earthquakes along such faults indicate that seismicity is highly concentrated within this fault damage zone. However, the long-term influence of the fault damage zone on complete earthquake cycles, i.e., years to centuries, is not well understood. We [...]
Analytical prediction of seismicity rate due to tides and other oscillating stresses
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences, Tectonics and Structure
Oscillatory stresses are ubiquitous on earth and other solid-surface bodies. Tides and seasonal signals perpetually stress faults in the crust. Relating seismicity to these stresses offers fundamental insight into earthquake triggering. We present a simple model that describes seismicity rate due to perpetual oscillatory stresses. The model applies to large amplitude, non-harmonic, and [...]
WORKSHOP REPORT: Securing Legacy Seismic Data to Enable Future Discoveries September 18-19, 2019 Albuquerque, New Mexico
Published: 2020-02-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
On September 18-19, 2019 a workshop on Securing Legacy Data to Enable Future Discoveries was held in Albuquerque, New Mexico engaging 29 researchers representing universities, national laboratories, and governmental agencies that included 4 international and 10 early career participants. The need and funding for this workshop grew out of a June 2018 event focused on legacy seismic data organized [...]
Inchworm-like source evolution through a geometrically complex fault fueled persistent supershear rupture during the 2018 Palu Indonesia earthquake
Published: 2020-02-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
How does fault slip follow an earthquake rupture front propagating faster than the local shear-wave velocity (i.e., at supershear speed)? How does a supershear rupture front pass through a geometrically complex fault system? Resolving the evolution of such complex earthquake ruptures is fundamental to our understanding of earthquake-source physics, but these events have not been well captured by [...]
Processing Seismic Ambient Noise Data with the Continuous Wavelet Transform to Obtain Reliable Empirical Green’s Functions
Published: 2020-02-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We propose a new data processing flow to compute empirical Green’s functions (EGF) from ambient seismic noise based on a soft thresholding designaling and denoising method using the continuous wavelet transform. The designaling algorithm is carried out during the initial data processing to remove earthquakes and other transient signals in the seismic record. A continuous wavelet transform [...]
Evidence of recurrent mass movement in front of the maximum slip area of the 1960 Chile earthquake: Implications for risk assessment and paleoseismology
Published: 2020-02-20
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics
We present evidence that suggests a new risk scenario for the Valdivia basin in south Chile, located in the area of the magnitude 9.5 1960 earthquake. In 1960, three mass movements, triggered by the earthquake shaking, dammed the upper course of the San Pedro River and threatened Valdivia City until it was opened in a controlled manner by its inhabitants. Published historical accounts indicate [...]
Array-based iterative measurements of SmKS travel times and their constraints on outermost core structure
Published: 2020-02-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Vigorous convection in Earths outer core led to the suggestion that it is chemically homogeneous. However, there is increasing seismic evidence for structural complexities close to the outer cores upper and lower boundaries. Both body waves and normal mode data have been used to estimate a P-wave velocity, Vp, at the top of the outer core (the E layer), which is lower than that in the Preliminary [...]
Large-scale crustal structure beneath Singapore using receiver functions from a dense urban nodal array
Published: 2020-02-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Geophysics has a role to play in the development of smart cities, for example through geohazard mitigation and subsurface imaging for underground construction. This is particularly true for Singapore, one of the worlds most densely populated countries. Imaging of Singapores subsurface is required to identify geological faults, model shaking from future earthquakes and provide a framework for [...]
Connecting a broad spectrum of transient slip on the San Andreas fault
Published: 2020-02-13
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Strain accumulated on the deep extension of some faults are episodically released during transient slow-slip events which can subsequently load the shallow seismogenic region. At the San Andreas fault, the characteristics of slow-slip events are difficult to constrain geodetically due to their small deformation signal. Slow-slip events are often accompanied by coincident tremor bursts composed of [...]
The 2019 MW 5.7 Changning earthquake, Sichuan Basin, China – a shallow doublet with different faulting styles
Published: 2020-02-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The increased seismic activity of the last ~10 years in Changning county of Sichuan Province comprised just small (mostly ML < 5.0) injection-induced earthquakes. The MW 5.7 earthquake of June 17, 2019 is the largest event ever reported there. Moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole. We resolve its fine structure showing it was a doublet, [...]
Impact of topography on earthquake static slip inversions
Published: 2020-02-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Our understanding of earthquakes is limited by our knowledge, and our description, of the physics of the Earth. When solving for subsurface fault slip, it is common practice to assume minimum complexity for the Earths characteristics such as topography, fault geometry and elastic properties. These characteristics are difficult to include in simulations and our knowledge of them is incomplete, [...]
Stress Changes on the Garlock fault during and after the 2019 Ridgecrest Earthquake Sequence
Published: 2020-02-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The recent 2019 Ridgecrest earthquake sequence in Southern California jostled the seismological community by revealing a complex and cascading foreshock series that culminated in a M7.1 mainshock. But the central Garlock fault, despite being located immediately south of this sequence, did not coseismically fail. Instead, the Garlock fault underwent post-seismic creep and exhibited a sizeable [...]
Fault rupture during the December 26, 2018, Mw 4.9 Fleri earthquake (Mt. Etna): surface faulting in a volcano-tectonic environment
Published: 2020-02-04
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
On December 26, 2018, the largest instrumental earthquake ever recorded in Mt. Etna (Sicily, southern Italy) shook the eastern flank of the volcano, with epicenter near the Fleri village along the right-lateral Fiandaca Fault (focal depth less than 1 km, Mw 4.9). The mainshock was accompanied by widespread surface faulting. We surveyed and mapped the coseismic ground ruptures and collected [...]