Spatial-temporal variation of low-frequency earthquake bursts near Parkfield, California

Geophysical Journal International
Wu, C; Guyer, R; Shelly, D; Trugman, D; Frank, W; Johnson,P
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Tectonic tremor (TT) and low-frequency earthquakes (LFEs) have been found in the deeper crust of various tectonic environments globally in the last decade. The spatial-temporal behaviour of LFEs provides insight into deep fault zone processes. In this study, we examine recurrence times from a 12-yr catalogue of 88 LFE families with ∼730 000 LFEs in the vicinity of the Parkfield section of the San Andreas Fault (SAF) in central California. We apply an automatic burst detection algorithm to the LFE recurrence times to identify the clustering behaviour of LFEs (LFE bursts) in each family. We find that the burst behaviours in the northern and southern LFE groups differ. Generally, the northern group has longer burst duration but fewer LFEs per burst, while the southern group has shorter burst duration but more LFEs per burst. The southern group LFE bursts are generally more correlated than the northern group, suggesting more coherent deep fault slip and relatively simpler deep fault structure beneath the locked section of SAF. We also found that the 2004 Parkfield earthquake clearly increased the number of LFEs per burst and average burst duration for both the northern and the southern groups, with a relatively larger effect on the northern group. This could be due to the weakness of northern part of the fault, or the northwesterly rupture direction of the Parkfield earthquake.

Publication type Article
Publication Subtype Journal Article
Title Spatial-temporal variation of low-frequency earthquake bursts near Parkfield, California
Series title Geophysical Journal International
DOI 10.1093/gji/ggv194
Volume 202
Issue 2
Year Published 2015
Language English
Publisher Royal Astronomical Society
Publisher location Oxford
Contributing office(s) Earthquake Science Center
First page 914
Last page 919
Country United States
State California
City Parkfield
Online Only (Y/N) N
Additional Online Files (Y/N) N
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