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

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.

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

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 Preliminary work on an early warning and rapid response program for moderate earthquakes

1995 ◽  
Vol 85 (4) ◽  
pp. 1257-1265
Author(s):  
Craig W. Scrivner ◽  
Donald V. Helmberger
Keyword(s):  
Ground Motion ◽  
Southern California ◽  
San Andreas Fault ◽  
Ground Motions ◽  
Source Parameters ◽  
Reverse Direction ◽  
Peak Displacement ◽  
San Andreas ◽  
Single Station ◽  
Sierra Madre

Abstract Warning of imminent ground shaking due to a large earthquake would be useful to a variety of agencies. This kind of ground-motion prediction is possible in southern California for events with magnitude less than 6, where path effects dominate. The 28 June 1991 Sierra Madre earthquake is presented as a test case for this concept. A single-station inversion of the record from the Pasadena station 20 km SW of the epicenter produces reasonable source parameters for the event. With these source parameters and a library of Green's functions calculated for an average southern California crustal model, ground motions can be predicted throughout the region. In particular, since the peak displacement for the Sierra Madre event occurs at Pasadena before ground motion begins at a station near the San Andreas Fault in San Bernardino, ground motions near the San Andreas Fault can be calculated before the seismic energy has propagated into the area. Considering this scenario in the reverse direction, records from a station near an earthquake on the San Andreas Fault could be used to predict ground motions in the metropolitan Los Angeles area. Broadband, high-dynamic-range seismic instruments produce high-quality records for events over a wide magnitude range. Thus, the development of a warning system can be approached in stages, starting with small events. With path effects determined by modeling moderate-size events, work can begin on developing distributed fault models to predict ground motions of great earthquakes.

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.

scholarly journals The slow self-arresting nature of low-frequency earthquakes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xueting Wei ◽  
Jiankuan Xu ◽  
Yuxiang Liu ◽  
Xiaofei Chen
Keyword(s):  
Source Parameters ◽  
Low Frequency ◽  
Slip Rates ◽  
Rupture Dynamics ◽  
San Andreas ◽  
Use Phase ◽  
Fault Deformation ◽  
Stress Drops ◽  
Unusual Type ◽  
Stress Accumulation

AbstractLow-frequency earthquakes are a series of recurring small earthquakes that are thought to compose tectonic tremors. Compared with regular earthquakes of the same magnitude, low-frequency earthquakes have longer source durations and smaller stress drops and slip rates. The mechanism that drives their unusual type of stress accumulation and release processes is unknown. Here, we use phase diagrams of rupture dynamics to explore the connection between low-frequency earthquakes and regular earthquakes. By comparing the source parameters of low-frequency earthquakes from 2001 to 2016 in Parkfield, on the San Andreas Fault, with those from numerical simulations, we conclude that low-frequency earthquakes are earthquakes that self-arrest within the rupture patch without any introduced interference. We also explain the scaling property of low-frequency earthquakes. Our findings suggest a framework for fault deformation in which nucleation asperities can release stress through slow self-arrest processes.

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