Two‐dimensional seismic image of the San Andreas Fault in the Northern Gabilan Range, central California: Evidence for fluids in the fault zone

Thurber, C. H.; Roecker, S. W.; Ellsworth, W. L.; Chen, Y.; Lutter, William J.; Sessions, R.

doi:10.1029/97gl01435

Cited by 110 publications

(89 citation statements)

References 23 publications

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“…Therefore, we think that the mainshock fault of the 2000 Western Tottori Earthquake represents young weak planes in a relatively homogeneous structure, instead of a boundary between different geological structures. Thurber et al (1997) found zones of low V p and high V p/V s (≥ 2.0) beneath the SAF. The high V p/V s zones extend to a depth of about 6 km and cut across areas of very different V p values.…”

Section: Discussionmentioning

confidence: 99%

High resolution 3-D velocity structure in the source region of the 2000 Western Tottori Earthquake in southwestern Honshu, Japan using very dense aftershock observations

Shibutani

Katao

2005

Earth Planet Sp

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We carried out high density aftershock observations a week after the 2000 Western Tottori Earthquake for 40 days. We deployed 72 seismic stations in and around the aftershock area. The average spacing of the stations in the aftershock area was 4-5 km. We determined accurate hypocenters and focal mechanisms for ∼1,000 aftershocks and obtained a high resolution 3-D velocity structure in the source region. High P and S wave velocity anomalies (> 4%) near the southeasternmost aftershock area at 2 km depth correlated with Jurassic to Late Cretaceous plutonic and high pressure metamorphic rocks. The depth distribution of the P and S wave velocities along the mainshock fault showed that high velocity anomalies were located at the shallow southeastern edge and the deeper central part of the aftershock area. The ratio between P and S wave velocities in the high velocity anomalies was a little higher (∼1.75) than the average value (∼1.70) in the upper crust. These results indicate that the high velocity anomalies could correspond to the plutonic or metamorphic rocks. The distributions of the high velocity anomalies and large slips of the mainshock were complementary. These suggest that the high velocity anomalies could be stronger than the surrounding materials and might behave as barriers to the mainshock rupture.

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Section: Discussionmentioning

confidence: 99%

High resolution 3-D velocity structure in the source region of the 2000 Western Tottori Earthquake in southwestern Honshu, Japan using very dense aftershock observations

Shibutani

Katao

2005

Earth Planet Sp

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“…The low-velocity and low-resistivity zone on the San Andreas fault (SAF) near Parkfield has been revealed by many researchers (e.g., Lees and Malin, 1990;Li et al, 1990;Ben-Zion and Malin, 1991;Michelini and McEvilly, 1991;Eberhart-Phillips and Michael, 1993;Thurber et al, 1997;Unsworth et al, 1997). Using fault-zone trapped waves recorded at the SAF near Parkfield (Li et al, 1997(Li et al, , 2004Korneev et al, 2003), an approximately 100-to 200-m wide low-velocity waveguide has been delineated on the SAF at seismogenic depths at which shear-velocities are reduced by 20-40%.…”

Section: Introductionmentioning

confidence: 99%

Seismic velocity variations on the San Andreas fault caused by the 2004 M6 Parkfield Earthquake and their implications

Chen

Cochran

et al. 2007

Earth Planet Sp

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mainshock show a peak of an approximately 2.5% decrease in seismic velocity at stations within the fault zone, most likely due to the co-seismic damage of fault-zone rocks during dynamic rupture of this earthquake. The damage zone is not symmetric; instead, it extends farther on the southwest side of the main fault trace. Seismic velocities within the fault zone measured for later repeated aftershocks in the following 3-4 months show an approximate 1.2% increase at seismogenic depths, indicating that the rock damaged in the mainshock recovers rigidity-or heals-through time. The healing rate was not constant but was largest in the earliest post-mainshock stage. The magnitude of fault damage and healing varies across and along the rupture zone, indicating that the greater damage was inflicted and thus greater healing is observed in regions with larger slip in the mainshock. Observations of rock damage during the mainshock and healing soon thereafter are consistent with our interpretation of the low-velocity waveguide on the SAF being at least partially softened in the 2004 M6 mainshock, with additional cumulative effects due to recurrent rupture.

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“…These shallow depth earthquakes (from the surface to ~10 km), might correspond to the activity of the Cimandiri fault zone. This fact is also shown by the other faults, for example the San Andreas fault system which extends more than 810 miles long from northern California southward to Cajon Pass near San Bernardino [11,12]. Figure 4 also show that in general the southwestern and central parts of the fault zone is seismically active than the northeastern part.…”

Section: Resultsmentioning

confidence: 51%

Seismicity around the Cimandiri fault zone, West Java, Indonesia

Febriani

2016

AIP Conference Proceedings

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Two‐dimensional seismic image of the San Andreas Fault in the Northern Gabilan Range, central California: Evidence for fluids in the fault zone

Cited by 110 publications

References 23 publications

High resolution 3-D velocity structure in the source region of the 2000 Western Tottori Earthquake in southwestern Honshu, Japan using very dense aftershock observations

High resolution 3-D velocity structure in the source region of the 2000 Western Tottori Earthquake in southwestern Honshu, Japan using very dense aftershock observations

Seismic velocity variations on the San Andreas fault caused by the 2004 M6 Parkfield Earthquake and their implications

Seismicity around the Cimandiri fault zone, West Java, Indonesia

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