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

Mostafa Khoshmanesh, Manoochehr Shirzaei

    Research output: Contribution to journalArticle

    2 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

    Fingerprint

    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

    @article{9abf72d5abea495aa8b9804167728eb2,
    title = "Episodic creep events on the San Andreas Fault caused by pore pressure variations",
    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.",
    author = "Mostafa Khoshmanesh and Manoochehr Shirzaei",
    year = "2018",
    month = "6",
    day = "18",
    doi = "10.1038/s41561-018-0160-2",
    language = "English (US)",
    pages = "1--5",
    journal = "Nature Geoscience",
    issn = "1752-0894",
    publisher = "Nature Publishing Group",

    }

    TY - JOUR

    T1 - Episodic creep events on the San Andreas Fault caused by pore pressure variations

    AU - Khoshmanesh, Mostafa

    AU - Shirzaei, Manoochehr

    PY - 2018/6/18

    Y1 - 2018/6/18

    N2 - 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.

    AB - 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.

    UR - http://www.scopus.com/inward/record.url?scp=85048670128&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=85048670128&partnerID=8YFLogxK

    U2 - 10.1038/s41561-018-0160-2

    DO - 10.1038/s41561-018-0160-2

    M3 - Article

    SP - 1

    EP - 5

    JO - Nature Geoscience

    JF - Nature Geoscience

    SN - 1752-0894

    ER -