Episodic creep events on the San Andreas Fault caused by pore pressure variations

Mostafa Khoshmanesh, Manoochehr Shirzaei

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Recent seismic and geodetic observations indicate that interseismic creep rate varies in both time and space. The spatial extent of creep pinpoints locked asperities, while its temporary accelerations, known as slow-slip events, may trigger earthquakes. Although the conditions promoting fault creep are well-studied, the mechanisms for initiating episodic slow-slip events are enigmatic. Here we investigate surface deformation measured by radar interferometry along the central San Andreas Fault between 2003 and 2010 to constrain the temporal evolution of creep. We show that slow-slip events are ensembles of localized creep bursts that aseismically rupture isolated fault compartments. Using a rate-and-state friction model, we show that effective normal stress is temporally variable on the fault, and support this using seismic observations. We propose that compaction-driven elevated pore fluid pressure in the hydraulically isolated fault zone and subsequent frictional dilation cause the observed slow-slip episodes. We further suggest that the 2004 Mw 6 Parkfield earthquake might have been triggered by a slow-slip event, which increased the Coulomb failure stress by up to 0.45 bar per year. This implies that while creeping segments are suggested to act as seismic rupture barriers, slow-slip events on these zones might promote seismicity on adjacent locked segments.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalNature Geoscience
DOIs
StateAccepted/In press - Jun 18 2018

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San Andreas Fault
pore pressure
creep
rupture
earthquake trigger
radar interferometry
asperity
dilation
fluid pressure
temporal evolution
seismicity
fault zone
compaction
friction
earthquake

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Cite this

Episodic creep events on the San Andreas Fault caused by pore pressure variations. / Khoshmanesh, Mostafa; Shirzaei, Manoochehr.

In: Nature Geoscience, 18.06.2018, p. 1-5.

Research output: Contribution to journalArticle

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