Short-range distance measurements along the San Andreas fault system in central California, 1975 to 1979

1981 ◽  
Vol 71 (5) ◽  
pp. 1607-1624
Author(s):  
M. Lisowski ◽  
W. H. Prescott
Keyword(s):  
San Andreas Fault ◽  
Slip Rate ◽  
San Juan ◽  
Distance Measurements ◽  
Slip Rates ◽  
Central California ◽  
San Andreas ◽  
Fault Slip Rates ◽  
San Juan Bautista ◽  
Wide Zone

abstract Periodic measurements of fault-crossing networks with a side length of 1 to 3 km are being made to monitor deformation across fault zones in California. The distance measurements are made with a Hewlett-Packard 3800 or 3808 electronic distance meter and have a maximum standard deviation of 5 mm. Deformation measured within networks that span the San Juan Bautista-Cholame segment of the San Andreas fault in central California yields slip rates similar to those measured across a 100- to 300-m-wide zone by repeated alinement array surveys. Fault slip rates increase from near 0 to 32 mm/yr between San Juan Bautista and Bitterwater Valley in step-like increments. From Bitterwater to Slack Canyon slip rates vary between 26 and 32 mm/yr. Slip rates decrease southwestward of Slack Canyon to 3 mm/yr at Cholame. In contrast, Geodolite measurements of deformation across a 20-km-wide zone are consistent from San Juan Bautista to Slack Canyon and imply a 32 ± 2 mm/yr slip rate. Deformation across the Calaveras fault accounts for the difference between Geodolite and near-fault slip rates between San Juan Bautista and Bear Valley, although the zone of deformation is wider than 2.5 km just south of Hollister. At Bear Valley, measurements of a short-range network crossing the Paicines fault imply a slip rate of 10 ± 3 mm/yr during the period 1976 to 1979. From Slack Canyon to Cholame, Geodolite measurements show a constant decrease in the rate of shallow slip.

scholarly journals New geodetic constraints on southern San Andreas fault-slip rates, San Gorgonio Pass, California

Geosphere ◽  
2020 ◽  
Author(s):  
Katherine A. Guns ◽  
Richard A Bennett ◽  
Joshua C. Spinler ◽  
Sally F. McGill
Keyword(s):  
Velocity Field ◽  
Southern California ◽  
San Andreas Fault ◽  
Plate Boundary ◽  
Slip Rate ◽  
Fault Slip ◽  
Slip Rates ◽  
San Andreas ◽  
Fault Slip Rates ◽  
Gps Velocity Field

Assessing fault-slip rates in diffuse plate boundary systems such as the San Andreas fault in southern California is critical both to characterize seis­mic hazards and to understand how different fault strands work together to accommodate plate boundary motion. In places such as San Gorgonio Pass, the geometric complexity of numerous fault strands interacting in a small area adds an extra obstacle to understanding the rupture potential and behavior of each individual fault. To better understand partitioning of fault-slip rates in this region, we build a new set of elastic fault-block models that test 16 different model fault geometries for the area. These models build on previ­ous studies by incorporating updated campaign GPS measurements from the San Bernardino Mountains and Eastern Transverse Ranges into a newly calculated GPS velocity field that has been removed of long- and short-term postseismic displacements from 12 past large-magnitude earthquakes to estimate model fault-slip rates. Using this postseismic-reduced GPS velocity field produces a best- fitting model geometry that resolves the long-standing geologic-geodetic slip-rate discrepancy in the Eastern California shear zone when off-fault deformation is taken into account, yielding a summed slip rate of 7.2 ± 2.8 mm/yr. Our models indicate that two active strands of the San Andreas system in San Gorgonio Pass are needed to produce sufficiently low geodetic dextral slip rates to match geologic observations. Lastly, results suggest that postseismic deformation may have more of a role to play in affecting the loading of faults in southern California than previously thought.

Seismic moments, local magnitudes, and coda-duration magnitudes for earthquakes in central California

1984 ◽  
Vol 74 (2) ◽  
pp. 439-458 ◽  
Author(s):  
William H. Bakun
Keyword(s):  
Seismic Moment ◽  
San Andreas Fault ◽  
Seismic Network ◽  
San Juan ◽  
Local Magnitude ◽  
Central California ◽  
San Andreas ◽  
Duration Magnitude ◽  
San Juan Bautista ◽  
The U.S

Abstract Onscale seismograms recorded at stations in the U.S. Geological Survey's (USGS) central California seismic network (CALNET) have been used to estimate the seismic moment M0 and local magnitude ML for earthquakes of 1 ≦ ML ≦ 4 located on the San Juan Bautista and Parkfield sections of the San Andreas fault, the Coyote Lake section of the Calaveras fault, the Sargent fault, and near Livermore. These data, together with M0 and ML estimates for 4 ≦ ML ≦ 6 earthquakes in these areas, cannot be fit with a single linear log M0-versus-ML relation. Rather, the data are consistent with log M0 = 1.5 ML + 16 for 3 ≲ ML ≲ 6, with log M0 = 1.2 ML + 17 for 1 1/2 ≲ ML ≲ 3 1/2 and with a slope of ⅔ to 1 fro 1/2 ≲ ML ≲ 1 1/2. Whereas USGS coda duration magnitude MD is consistent with ML for 1 1/2 ≲ ML ≲ 3¼, MD is larger than ML at ML ≲ 1 1/2 and smaller than ML at ML ≳ 3¼. Log M0 can be estimated to a precision of 0.2 for 1 ≦ MD ≦ 3 1/2 earthquakes in central California by applying log M0 = 1.2 MD + 17 to the MD that have been routinely published by the USGS.

scholarly journals A revised position for the primary strand of the Pleistocene-Holocene San Andreas fault in southern California

2021 ◽  
Vol 7 (13) ◽  
pp. eaaz5691
Author(s):  
Kimberly Blisniuk ◽  
Katherine Scharer ◽  
Warren D. Sharp ◽  
Roland Burgmann ◽  
Colin Amos ◽  
...  
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Large Magnitude ◽  
Slip Rates ◽  
San Andreas ◽  
The Pacific ◽  
Large Earthquakes ◽  
Dependent Probability

The San Andreas fault has the highest calculated time-dependent probability for large-magnitude earthquakes in southern California. However, where the fault is multistranded east of the Los Angeles metropolitan area, it has been uncertain which strand has the fastest slip rate and, therefore, which has the highest probability of a destructive earthquake. Reconstruction of offset Pleistocene-Holocene landforms dated using the uranium-thorium soil carbonate and beryllium-10 surface exposure techniques indicates slip rates of 24.1 ± 3 millimeter per year for the San Andreas fault, with 21.6 ± 2 and 2.5 ± 1 millimeters per year for the Mission Creek and Banning strands, respectively. These data establish the Mission Creek strand as the primary fault bounding the Pacific and North American plates at this latitude and imply that 6 to 9 meters of elastic strain has accumulated along the fault since the most recent surface-rupturing earthquake, highlighting the potential for large earthquakes along this strand.

scholarly journals Latest Quaternary slip rates of the San Bernardino strand of the San Andreas fault, southern California, from Cajon Creek to Badger Canyon

Geosphere ◽  
2021 ◽  
Author(s):  
Sally F. McGill ◽  
Lewis A. Owen ◽  
Ray J. Weldon ◽  
Katherine J. Kendrick ◽  
Reed J. Burgette
Keyword(s):  
Confidence Interval ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Alluvial Fan ◽  
Slip Rates ◽  
San Jacinto Fault ◽  
The Past ◽  
San Andreas ◽  
San Jacinto Fault Zone ◽  
San Bernardino

Four new latest Pleistocene slip rates from two sites along the northwestern half of the San Bernardino strand of the San Andreas fault suggest the slip rate decreases southeastward as slip transfers from the Mojave section of the San Andreas fault onto the northern San Jacinto fault zone. At Badger Canyon, offsets coupled with radiocarbon and optically stimulated luminescence (OSL) ages provide three independent slip rates (with 95% confidence intervals): (1) the apex of the oldest dated alluvial fan (ca. 30–28 ka) is right-laterally offset ~300–400 m yielding a slip rate of 13.5 +2.2/−2.5 mm/yr; (2) a terrace riser incised into the northwestern side of this alluvial fan is offset ~280–290 m and was abandoned ca. 23 ka, yielding a slip rate of 11.9 +0.9/−1.2 mm/yr; and (3) a younger alluvial fan (13–15 ka) has been offset 120–200 m from the same source canyon, yielding a slip rate of 11.8 +4.2/−3.5 mm/yr. These rates are all consistent and result in a preferred, time-averaged rate for the past ~28 k.y. of 12.8 +5.3/−4.7 mm/yr (95% confidence interval), with an 84% confidence interval of 10–16 mm/yr. At Matthews Ranch, in Pitman Canyon, ~13 km northwest of Badger Canyon, a landslide offset ~650 m with a 10Be age of ca. 47 ka yields a slip rate of 14.5 +9.9/−6.2 mm/yr (95% confidence interval). All of these slip rates for the San Bernardino strand are significantly slower than a previously published rate of 24.5 ± 3.5 mm/yr at the southern end of the Mojave section of the San Andreas fault (Weldon and Sieh, 1985), suggesting that ~12 mm/yr of slip transfers from the Mojave section of the San Andreas fault to the northern San Jacinto fault zone (and other faults) between Lone Pine Canyon and Badger Canyon, with most (if not all) of this slip transfer happening near Cajon Creek. This has been a consistent behavior of the fault for at least the past ~47 k.y.

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

1994 ◽  
Vol 99 (B3) ◽  
pp. 4559-4565 ◽  
Author(s):  
M. T. Gladwin ◽  
R. L. Gwyther ◽  
R. H. G. Hart ◽  
K. S. Breckenridge
Keyword(s):  
Strain Field ◽  
San Andreas Fault ◽  
San Juan ◽  
San Andreas ◽  
San Juan Bautista

scholarly journals Variability of fault slip behavior along the San Andreas Fault in the San Juan Bautista Region

2014 ◽  
Vol 119 (12) ◽  
pp. 8827-8844 ◽  
Author(s):  
Taka'aki Taira ◽  
Roland Bürgmann ◽  
Robert M. Nadeau ◽  
Douglas S. Dreger
Keyword(s):  
San Andreas Fault ◽  
Fault Slip ◽  
San Juan ◽  
San Andreas ◽  
San Juan Bautista

Late Holocene Slip Rate of the Mojave Section of the San Andreas Fault near Palmdale, California

2021 ◽  
Author(s):  
Elaine K. Young ◽  
Eric Cowgill ◽  
Katherine M. Scharer ◽  
Emery O. Anderson-Merritt ◽  
Amanda Keen-Zebert ◽  
...  
Keyword(s):  
Late Holocene ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Earthquake Hazard ◽  
Luminescence Dating ◽  
Geologic Mapping ◽  
Slip Rates ◽  
San Andreas ◽  
Aleatory Variability

ABSTRACT The geologic slip rate on the Mojave section of the San Andreas fault is poorly constrained, despite its importance for understanding earthquake hazard, apparent discrepancies between geologic and geodetic slip rates along this fault section, and long-term fault interactions in southern California. Here, we use surficial geologic mapping, excavations, and radiocarbon and luminescence dating to quantify the displacements and ages of late Holocene landforms offset by the fault at three sites. At the Ranch Center site, the slip rate is determined using the base of a fan marking incision and deflection of an ephemeral channel. At the adjacent Key Slide site, the margin of a landslide deposited on indigenous fire hearths provides a minimum rate. At the X-12 site, the slip rate is determined from a channel that incised into a broad fan surface, and is deflected and beheaded by the fault. We use maximum–minimum bounds on both the displacement and age of each offset feature to calculate slip rate for each site independently. Overlap of the three independent rate ranges yields a rate of 33–39 mm/yr over the last 3 ka, under the assumption that the sites share a common history, given their proximity. Considered in sequence, site-level epistemic uncertainties in the data permit but do not require a rate increase since ∼1200 cal B.P. Modest rate changes can be explained by aleatory variability in earthquake timing and magnitude; larger changes could suggest a shared regional variation with the Garlock and other faults. The new late Holocene slip rates are consistent with geodetic model estimates that include a viscoelastic crust and earthquake cycle effects. The geologic slip rates also provide average slip over dozens of earthquake cycles—a key constraint for long-term earthquake rupture forecasts.

scholarly journals Supplemental Material: New geodetic constraints on southern San Andreas fault-slip rates, San Gorgonio Pass, California

2020 ◽  
Author(s):  
K.A. Guns ◽  
et al.
Keyword(s):  
San Andreas Fault ◽  
Strike Slip ◽  
Fault Slip ◽  
Full Model ◽  
Slip Rates ◽  
San Andreas ◽  
Fault Slip Rates ◽  
Gps Velocities

<div>Includes tables of statistical details regarding estimation of GPS velocities (including the map position and names of all campaign and continuous station sites) and the full model assessments of fit. Also includes figures that present details of all strike-slip and dip-slip fault-slip rates calculated within models.<br></div>

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