Measurements of the strain field associated with episodic creep events on the San Andreas Fault at San Juan Bautista, California

Gladwin, M. T.; Gwyther, R. L.; Hart, R. H. G.; Breckenridge, K. S.

doi:10.1029/93jb02877

Cited by 63 publications

(56 citation statements)

References 24 publications

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“…There may be an analogy here with the well-documented episodic creep behaviour in normally consolidated near-surface sediments along the San Andreas transform fault system. Some of those creep events have propagation velocities of c. 1 km h 1 and result in slip over zones of area c. 0.3 km 2 or more (Goulty & Gilman 1978;Evans et al 1981;Gladwin et al 1994). These dimensions are comparable to the areas of polygonal fault surfaces.…”

Section: Fluid-escape Featuresmentioning

confidence: 96%

Geomechanics of polygonal fault systems: a review

Goulty

2008

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Layer-bound systems of polygonal faults are found in sequences of very fine-grained sediments that have typically undergone passive subsidence and burial. In the absence of tectonic extension, the heave of the faults must be complemented by horizontal compaction of the sediments. Density inversion, syneresis and low coefficients of friction on fault planes have all been proposed as causal mechanisms for the development of polygonal fault systems, but most sequences that contain polygonal faults are not underlain by sediments of lower density and there is a lack of evidence to support the idea that syneresis is responsible. Laboratory measurements of clay properties and a recent field test based on well data strongly suggest that low coefficients of residual friction in fine-grained sediments are key to the growth of faults that eventually develop into polygonal systems. However, coefficients of residual friction apply to faults only after initial slip has taken place, so some other mechanism must be responsible for the initial nucleation of the faults. Various speculative suggestions have been made, but there is no evidence that nucleation of those faults that evolve into polygonal systems differs fundamentally from the processes involved in the nucleation of other faults in soft sediments.

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Section: Fluid-escape Featuresmentioning

confidence: 96%

Geomechanics of polygonal fault systems: a review

Goulty

2008

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“…Slow earthquakes have been observed in Japan and California as nearly exponential strain changes with durations ranging from about 1 hour to 3 days and strain steps larger than 3 X lo-' (1)(2)(3)(4). Indirect evidence for slow earthquakes comes froin seismograms with anomalous long-period spectral behavior (5)(6)(7)(8)(9).…”

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confidence: 99%

Constraints on Slow Earthquake Dynamics from a Swarm in Central Italy

Crescentini

Amoruso

Scarpa

1999

Science

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Several clustered slow earthquakes have been recorded by a geodetic interferometer in central Italy. The strain rise times of the events range from tens to thousands of seconds, and the seismic moment scales with the square root of the rise time. This scaling law contrasts with the conservative assumption of constant rupture velocity in fault modeling but is consistent with the occurrence of a slow rupture propagation analogous to heat diffusion in a slab.

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“…[2] Observations in Japan and California have proved the existence of faulting processes other than creeping (almost continuous slip without stress buildup) and regular earthquakes (sudden release of accumulated stress) [e.g., Sacks et al, 1978;Gladwin et al, 1994;Kawasaki et al, 1995;Linde et al, 1996]. These phenomena, known as slow earthquakes, have characteristic time scales ranging from tens of seconds to days, and release accumulated stress too slowly to produce seismic waves recordable by seismometers.…”

Section: Introductionmentioning

confidence: 99%

Slow rupture of an aseismic fault in a seismogenic region of Central Italy

Amoruso

Crescentini

Morelli

et al. 2002

Geophysical Research Letters

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Slow earthquakes and afterslips prove that the Earth does not have just two response time scales, i.e. that of tectonic loading and that of regular earthquakes. A swarm of slow earthquakes, with time constants of the order of hundreds of seconds, has been detected by a laser interferometer below the Gran Sasso massif (Italy). We analyse and model these observations to identify a very plausible source in a local fault, with no historic seismic behavior. While slow earthquakes occurring in subduction zones, and at the transition between locked and stably sliding segments of the San Andreas fault, are often associated with seismic events, in the case of the Apennines there is no correlation between local seismicity and slow earthquakes. Slow earthquakes, therefore, may also represent a specific failure behavior for a seismically locked fault, adding further complexity to the interpretation of geologic data for seismic hazard estimates.

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Measurements of the strain field associated with episodic creep events on the San Andreas Fault at San Juan Bautista, California

Cited by 63 publications

References 24 publications

Geomechanics of polygonal fault systems: a review

Geomechanics of polygonal fault systems: a review

Constraints on Slow Earthquake Dynamics from a Swarm in Central Italy

Slow rupture of an aseismic fault in a seismogenic region of Central Italy

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