Identification of low‐frequency earthquakes on the San Andreas fault with deep learning

2021 ◽  
Author(s):  
A. M. Thomas ◽  
A. Inbal ◽  
J. Searcy ◽  
D. R. Shelly ◽  
R. Bürgmann
Keyword(s):  
Deep Learning ◽  
San Andreas Fault ◽  
Low Frequency ◽  
San Andreas

Learning the low frequency earthquake daily intensity on the central San Andreas Fault

2020 ◽  
Author(s):  
Christopher Johnson ◽  
Claudia Hulbert ◽  
Bertrand Rouet-Leduc ◽  
Paul Johnson
Keyword(s):  
San Andreas Fault ◽  
Low Frequency ◽  
San Andreas

Near-field observations and source parameters of central California earthquakes

1974 ◽  
Vol 64 (6) ◽  
pp. 1855-1886 ◽  
Author(s):  
Lane R. Johnson ◽  
Thomas V. McEvilly
Keyword(s):  
San Andreas Fault ◽  
Strong Dependence ◽  
Source Parameters ◽  
Broad Band ◽  
Low Frequency ◽  
Corner Frequency ◽  
Fault Plane Solutions ◽  
Low Frequencies ◽  
Central California ◽  
San Andreas

abstract This is a study of source characteristics of 13 earthquakes with magnitudes between 2.4 and 5.1 located near the San Andreas fault in central California. On the basis of hypocentral locations and fault-plane solutions the earthquakes separate into two source groups, one group clearly related to the throughgoing northwest-trending San Andreas fault zone and the other apparently associated with generally north-trending bifurcations such as the Calaveras fault. The basic data consist of broad-band recordings (0.03 to 10 Hz) of these earthquakes at two sites of the San Andreas Geophysical Observatory (SAGO). Epicentral distances range between 2 and 40 km, and maximum ground displacements from 4 to 4000 microns were recorded. The whole-record spectra computed from the seismograms lend themselves to source parameter studies in that they can be interpreted in terms of low-frequency level, corner frequency, and high-frequency slope. Synthetic seismograms have also been used to estimate source parameters in both the time domain and frequency domain, and the results compare favorably with those estimated directly from the spectra. The influences of tilts and nonlinear response of the seismometer were considered in the interpretation of the low frequencies. Seismic source moments estimated from the low-frequency levels of the spectra show a linear dependence on magnitude with a slope slightly greater than 1. The geology at the recording site can contribute an uncertainty factor of at least 3 to the estimated moments. Observed corner frequencies are only weakly dependent on magnitude. Interpreted in terms of source dimension, these corner frequencies imply values of 1 to 2 km for the earthquakes of this study. The corner frequencies may also be interpreted in terms of the rise time source function, yielding values in the range 0.5 to 1.0 sec. The data indicate that the earthquakes of this study are all surprisingly similar in their fundamental source parameters, with only the seismic moment showing a strong dependence on magnitude.

scholarly journals Using Low-Frequency Earthquake Families on the San Andreas Fault as Deep Creepmeters

2018 ◽  
Vol 123 (1) ◽  
pp. 457-475 ◽  
Author(s):  
A. M. Thomas ◽  
N. M. Beeler ◽  
Q. Bletery ◽  
R. Burgmann ◽  
D. R. Shelly
Keyword(s):  
San Andreas Fault ◽  
Low Frequency ◽  
San Andreas

scholarly journals Constraints on the source parameters of low‐frequency earthquakes on the San Andreas Fault

2016 ◽  
Vol 43 (4) ◽  
pp. 1464-1471 ◽  
Author(s):  
Amanda M. Thomas ◽  
Gregory C. Beroza ◽  
David R. Shelly
Keyword(s):  
San Andreas Fault ◽  
Source Parameters ◽  
Low Frequency ◽  
San Andreas

Along‐Strike Variations in Fault Frictional Properties along the San Andreas Fault near Cholame, California, from Joint Earthquake and Low‐Frequency Earthquake Relocations

2016 ◽  
Vol 106 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Rebecca M. Harrington ◽  
Elizabeth S. Cochran ◽  
Emily M. Griffiths ◽  
Xiangfang Zeng ◽  
Clifford H. Thurber
Keyword(s):  
San Andreas Fault ◽  
Low Frequency ◽  
Frictional Properties ◽  
San Andreas

scholarly journals Connecting a broad spectrum of transient slip on the San Andreas fault

2020 ◽  
Vol 6 (33) ◽  
pp. eabb2489
Author(s):  
Yen Joe Tan ◽  
David Marsan
Keyword(s):  
Broad Spectrum ◽  
San Andreas Fault ◽  
Low Frequency ◽  
Small Deformation ◽  
Slow Slip ◽  
Rupture Velocity ◽  
Slow Slip Events ◽  
Temporal Decay ◽  
San Andreas ◽  
Aftershock Sequences

Strain accumulated on the deep extension of some faults is 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 (SSEs) are often accompanied by coincident tremor bursts composed of many low-frequency earthquakes. Here, we probabilistically estimate the spatiotemporal clustering properties of low-frequency earthquakes detected along the central San Andreas fault. We find that tremor bursts follow a power-law spatial and temporal decay similar to earthquake aftershock sequences. The low-frequency earthquake clusters reveal that the underlying slow-slip events have two modes of rupture velocity. Compared to regular earthquakes, these slow-slip events have smaller stress drop and rupture velocity but follow similar magnitude-frequency, moment-area, and moment-duration scaling. Our results connect a broad spectrum of transient fault slip that spans several orders of magnitude in rupture velocity.

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