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A search in strainmeter data for slow slip associated with triggered and ambient tremor near Parkfield, California

Journal of Geophysical Research B: Solid Earth

By:
and
DOI: 10.1029/2008JB006040

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Abstract

We test the hypothesis that, as in subduction zones, slow slip facilitates triggered and ambient tremor in the transform boundary setting of California. Our study builds on the study of Peng et al. (2009) of triggered and ambient tremor near Parkfield, California during time intervals surrounding 31, potentially triggering, M ≥ 7.5 teleseismic earthquakes; waves from 10 of these triggered tremor and 29 occurred in periods of ambient tremor activity. We look for transient slow slip during 3-month windows that include 11 of these triggering and nontriggering teleseisms, using continuous strain data recorded on two borehole Gladwin tensor strainmeters (GTSM) located within the distribution of tremor epicenters. We model the GTSM data assuming only tidal and “drift” signals are present and find no detectable slow slip, either ongoing when the teleseismic waves passed or triggered by them. We infer a conservative detection threshold of about 5 nanostrain for abrupt changes and about twice this for slowly evolving signals. This could be lowered slightly by adding analyses of other data types, modeled slow slip signals, and GTSM data calibration. Detection of slow slip also depends on the slipping fault's location and size, which we describe in terms of equivalent earthquake moment magnitude, M. In the best case of the GTSM above a very shallow slipping fault, detectable slip events must exceed M~2, and if the slow slip is beneath the seismogenic zone (below ~15 km depth), even M~5 events are likely to remain hidden.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A search in strainmeter data for slow slip associated with triggered and ambient tremor near Parkfield, California
Series title:
Journal of Geophysical Research B: Solid Earth
DOI:
10.1029/2008JB006040
Volume
114
Issue:
12
Year Published:
2009
Language:
English
Publisher:
Wiley
Contributing office(s):
Earthquake Hazards Program
Description:
B00A14
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research B: Solid Earth