Rapid creep on the San Andreas fault at Bitterwater Valley

Hay, E. A.; Hall, N. Timothy; Cotton, W. R.

doi:10.1029/ft309p0036

Cited by 3 publications

(3 citation statements)

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“…Most of our exposures did not provide evidence for individual earthquakes. In most exposures, the fault zone extended effectively to the ground surface or into massive, fine-grained units near the surface through which faulting was difficult or impossible to trace, consistent with a creeping fault (Hay et al, 1989). However, in two exposures, trenches 2 and 6, we documented upward fault terminations that we interpret to be the result of coseismic slip during an earthquake.…”

Section: Prehistoric Surface Rupturementioning

confidence: 71%

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

Prentice¹,

Larsen²,

Kelsey³

et al. 2014

Bulletin of the Seismological Society of America

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The Maacama fault is the northward continuation of the Hayward-Rodgers Creek fault system and creeps at a rate of 5:7 0:1 mm=yr (averaged over the last 20 years) in Willits, California. Our paleoseismic studies at Haehl Creek suggest that the Maacama fault has produced infrequent large earthquakes in addition to creep. Fault terminations observed in several excavations provide evidence that a prehistoric surfacerupturing earthquake occurred between 1060 and 1180 calibrated years (cal) B.P. at the Haehl Creek site. A folding event, which we attribute to a more recent large earthquake, occurred between 790 and 1060 cal B.P. In the last 560-690 years, a buried channel deposit has been offset 4:6 0:2 m, giving an average slip rate of 6:4-8:6 mm=yr, which is higher than the creep rate over the last 20 years. The difference between this slip rate and the creep rate suggests that coseismic slip up to 1.7 m could have occurred after the formation of the channel deposit and could be due to a paleoearthquake known from paleoseismic studies in the Ukiah Valley, about 25 km to the southeast. Therefore, we infer that at least two, and possibly three, large earthquakes have occurred at the Haehl Creek site since 1180 cal B.P. (770 C.E.), consistent with earlier studies suggesting infrequent, large earthquakes on the Maacama fault. The short-term geodetic slip rate across the Maacama fault zone is approximately twice the slip rate that we have documented at the Haehl Creek site, which is averaged over the last approximately 600 years. If the geodetic rate represents the long-term slip accumulation across the fault zone, then we infer that, in the last ∼1200 years, additional earthquakes may have occurred either on the Haehl Creek segment of the Maacama fault or on other active faults within the Maacama fault zone at this latitude. Online Material: Trench logs, discussion of channel B, photographs of compressional features, and table of radiocarbon analyses.

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Section: Prehistoric Surface Rupturementioning

confidence: 71%

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

Prentice¹,

Larsen²,

Kelsey³

et al. 2014

Bulletin of the Seismological Society of America

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“…Hay et al . [] do find a long‐term rate of at least 28 mm/yr at Flook Ranch, near Bitterwater valley; however, they find a much higher rate of 34 mm/yr since 1885. The nearest well‐documented rates are 26 + 6.4/ − 4.3 at Parkfield [ Toké et al ., ] and 34 +/− 3 mm/yr at Wallace Creek on the Carrizo segment [ Sieh and Jahns , ].…”

Section: Discussionmentioning

confidence: 83%

Fault coupling and potential for earthquakes on the creeping section of the central San Andreas Fault

Maurer

Johnson

2014

JGR Solid Earth

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The 150 km long central section of the San Andreas Fault (CSAF) in central California creeps at the surface and has not produced a large earthquake historically. However, sections of the San Andreas Fault to the north and south are known to have ruptured repeatedly in M~7-8 earthquakes. It is currently unclear whether the creeping CSAF could rupture in large earthquakes, either individually or along with earthquakes on the locked sections to the north and south. We invert Global Positioning System and interferometric synthetic aperture radar data with elastic block models to estimate the degree of locking on the CSAF and place bounds on the moment accumulation rate on the fault. We find that the inferred moment accumulation rate is highly dependent on the long-term fault slip rate, which is poorly constrained along the CSAF. The inferred moment accumulation rate, normalized by shear modulus, ranges from 3.28 × 10 4 to 5.85 × 10 7 m 3 /yr, which is equivalent to a M w = 5.5-7.2 earthquake every 150 years for a long-term slip rate of 26 mm/yr and M w = 7.3-7.65 for a long-term slip rate of 34 mm/yr. The comparisons of slip distributions with microseismicity and repeating earthquakes indicate a possible locked patch between 10 and 20 km depth on the CSAF that could potentially rupture with M w = 6.5.

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“…Thus, the Hayward fault presents a challenge in paleoseismology because we need to distinguish evidence of distinct coseismic surface ruptures associated with paleoearthquakes from deformation produced by interseismic creep. Previous studies along creeping faults have attempted to distinguish between features generated by creep and features created by coseismic rupture with equivocal results (Hay et al, 1989;Stenner and Ueta, 2000). Several types of evidence that may be indicative of the occurrence of a ground-rupturing event along a fault accompanying a large earthquake may become moot for creeping fault traces (Kelson and Baldwin, 2001).…”

Section: Evidence For Paleoearthquakesmentioning

confidence: 97%

A Record of Large Earthquakes on the Southern Hayward Fault for the Past 500 Years

Lienkaemper¹,

Dawson²,

Personius³

et al. 2002

Bulletin of the Seismological Society of America

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The Hayward fault, a major branch of the right-lateral San Andreas fault system, traverses the densely populated eastern San Francisco Bay region, California. We conducted a paleoseismic investigation to better understand the Hayward fault's past earthquake behavior. The site is near the south end of Tyson's Lagoon, a sag pond formed in a right step of the fault in Fremont. Because the Hayward fault creeps at the surface, we identified paleoseismic events using features that we judge to be unique to ground ruptures or the result of strong ground motion, such as the presence of fault-scarp colluvial deposits and liquefaction. We correlate the most recent event evidence (E1) to the historical 1868 M 6.9 earthquake that caused liquefaction in the pond and recognize three additional paleoruptures since A.D. 1470 ‫ע‬ 110 yr. Event ages were estimated by chronological modeling, which incorporated historical and stratigraphic information and radiocarbon and pollen data. Modeled, mean age and 95-percentile ranges of the three earlier events are A.

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Rapid creep on the San Andreas fault at Bitterwater Valley

Cited by 3 publications

References 0 publications

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

Late Holocene Slip Rate and Ages of Prehistoric Earthquakes along the Maacama Fault Near Willits, Mendocino County, Northern California

Fault coupling and potential for earthquakes on the creeping section of the central San Andreas Fault

A Record of Large Earthquakes on the Southern Hayward Fault for the Past 500 Years

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