Slip on the San Andreas Fault at Parkfield, California, over Two Earthquake Cycles, and the Implications for Seismic Hazard

2006 ◽  
Vol 96 (4B) ◽  
pp. S283-S303 ◽  
Author(s):  
J. Murray
Keyword(s):  
Seismic Hazard ◽  
San Andreas Fault ◽  
San Andreas ◽  
Earthquake Cycles

scholarly journals Fractal properties and simulation of micro-seismicity for seismic hazard analysis: a comparison of North Anatolian and San Andreas Fault Zones

2012 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Naside Ozer ◽  
Savas Ceylan
Keyword(s):  
Fractal Dimension ◽  
Seismic Hazard ◽  
Fault Zone ◽  
San Andreas Fault ◽  
Fractal Dimensions ◽  
Fault Zones ◽  
Group Method ◽  
Western Anatolia ◽  
P Value ◽  
San Andreas

We analyzed statistical properties of earthquakes in western Anatolia as well as the North Anatolian Fault Zone (NAFZ) in terms of spatio-temporal variations of fractal dimensions, p- and b-values. During statistically homogeneous periods characterized by closer fractal dimension values, we propose that occurrence of relatively larger shocks (M >= 5.0) is unlikely. Decreases in seismic activity in such intervals result in spatial b-value distributions that are primarily stable. Fractal dimensions decrease with time in proportion to increasing seismicity. Conversely, no spatiotemporal patterns were observed for p-value changes. In order to evaluate failure probabilities and simulate earthquake occurrence in the western NAFZ, we applied a modified version of the renormalization group method. Assuming an increase in small earthquakes is indicative of larger shocks, we apply the mentioned model to micro-seismic (M<= 3.0) activity, and test our results using San Andreas Fault Zone (SAFZ) data. We propose that fractal dimension is a direct indicator of material heterogeneity and strength. Results from a model suggest simulated and observed earthquake occurrences are coherent, and may be used for seismic hazard estimation on creeping strike-slip fault zones.

Seismic hazard analyses of the Metropolitan Water District Emergency Freshwater Pathway, California

2021 ◽  
pp. 875529302110476
Author(s):  
Ivan Wong ◽  
Patricia Thomas ◽  
Nora Lewandowski ◽  
Jeffrey Unruh ◽  
Bob Darragh ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
San Andreas Fault ◽  
Site Response ◽  
Fault System ◽  
Seismic Sources ◽  
Central California ◽  
San Andreas ◽  
San Andreas Fault System ◽  
Water District

The Sacramento-San Joaquin Delta in central California is particularly susceptible to damage in a large earthquake due to the vulnerability of the levees that protect cities, farms, and infrastructure. The Delta is located adjacent to the seismically active San Andreas fault system and is also subject to strong ground shaking from numerous other seismic sources in central California, including faults within the Delta. We performed a probabilistic seismic hazard analysis (PSHA) to provide seismic design ground motions for the Metropolitan Water District (MWD) Emergency Freshwater Pathway. We have evaluated the appropriateness of the Next Generation of Attenuation (NGA)-West2 ground motion models for use in our analyses of the Delta, evaluated shear-wave velocity ( VS) data in the vicinity of the Pathway, and performed site response analyses. The latter was performed to compute the probabilistic hazard at the top of the peat at five sites along the Pathway. The sixth site was located outside the Delta and on firm soil. The probabilistic hazard for the six sites and for a range of return periods of engineering relevance were computed in the PSHA. For a return period of 2500 years, the peak horizontal ground acceleration (PGA) values on peat ranged from 0.40 g to 0.53 g. The seismic sources that control the hazard at these sites vary as a function of return period and spectral frequency, but in general, the closer the sites are to faults within the San Andreas fault system, the higher the hazard.

scholarly journals A case for historic joint rupture of the San Andreas and San Jacinto faults

2016 ◽  
Vol 2 (3) ◽  
pp. e1500621 ◽  
Author(s):  
Julian C. Lozos
Keyword(s):  
Seismic Hazard ◽  
Southern California ◽  
San Andreas Fault ◽  
Plate Boundary ◽  
Data Sets ◽  
Dynamic Rupture ◽  
San Jacinto Fault ◽  
Fault Behavior ◽  
San Andreas ◽  
Primary Plate

The San Andreas fault is considered to be the primary plate boundary fault in southern California and the most likely fault to produce a major earthquake. I use dynamic rupture modeling to show that the San Jacinto fault is capable of rupturing along with the San Andreas in a single earthquake, and interpret these results along with existing paleoseismic data and historic damage reports to suggest that this has likely occurred in the historic past. In particular, I find that paleoseismic data and historic observations for the ~M7.5 earthquake of 8 December 1812 are best explained by a rupture that begins on the San Jacinto fault and propagates onto the San Andreas fault. This precedent carries the implications that similar joint ruptures are possible in the future and that the San Jacinto fault plays a more significant role in seismic hazard in southern California than previously considered. My work also shows how physics-based modeling can be used for interpreting paleoseismic data sets and understanding prehistoric fault behavior.

On the variation of seismic hazard along the San Andreas fault

1984 ◽  
Vol 74 (2) ◽  
pp. 709-723
Author(s):  
B. F. Howell
Keyword(s):  
Seismic Hazard ◽  
San Francisco ◽  
San Andreas Fault ◽  
The Other ◽  
Plain Area ◽  
San Andreas ◽  
Focal Area ◽  
Large Ratio ◽  
Earthquake Size

Abstract Recurrence probabilities of earthquakes were evaluated at 33 locations along the San Andreas fault using Gumbel's method. Two minima in the mode of the largest annual earthquakes occur, one north of San Francisco centered around 38.75°N latitude and the other centered in the Carizzo Plain area at 35.25°N latitude. The latter is offset by an unusually large ratio of large to small earthquakes, so that only one minimum (around 38.75°N) is observed in the expected 100-yr earthquake size. This broad minimum closely coincides with where the San Andreas fault broke in 1906, and may be only temporary. There appears to be a slight, systematic tendency for the observed largest 50-year earthquake to become larger than the expected 50-yr earthquake as the size of the area being studied is reduced. The preferred explanation for this is that the pattern of size as a function of frequency becomes nonlinear when the size of the area studied is less than the focal area of the largest earthquakes.

scholarly journals Prehistoric earthquakes on the Banning strand of the San Andreas fault, North Palm Springs, California

Geosphere ◽  
2021 ◽  
Author(s):  
Bryan A. Castillo ◽  
Sally F. McGill ◽  
Katherine M. Scharer ◽  
Doug Yule ◽  
Devin McPhillips ◽  
...  
Keyword(s):  
Fault Zone ◽  
San Andreas Fault ◽  
Recurrence Interval ◽  
Recent Event ◽  
Elapsed Time ◽  
San Andreas ◽  
Clay Deposits ◽  
Palm Springs ◽  
Detailed Record ◽  
Earthquake Cycles

We studied a paleoseismic trench excavated in 2017 across the Banning strand of the San Andreas fault and herein provide the first detailed record of ground-breaking earthquakes on this important fault in Southern California. The trench exposed an ~40-m-wide fault zone cutting through alluvial sand, gravel, silt, and clay deposits. We evaluated the paleoseismic record using a new metric that combines event indicator quality and stratigraphic uncertainty. The most recent paleoearthquake occurred between 950 and 730 calibrated years B.P. (cal yr B.P.), potentially contemporaneous with the last rupture of the San Gorgonio Pass fault zone. We interpret five surface-rupturing earthquakes since 3.3–2.5 ka and eight earthquakes since 7.1–5.7 ka. It is possible that additional events have occurred but were not recognized, especially in the deeper (older) section of the stratigraphy, which was not fully exposed across the fault zone. We calculated an average recurrence interval of 380–640 yr based on four complete earthquake cycles between earthquakes 1 and 5. The average recurrence interval is thus slightly less than the elapsed time since the most recent event on the Banning strand. The average recurrence interval on the Banning strand is thus intermediate between longer intervals published for the San Gorgonio Pass fault zone (~1600 yr) and shorter intervals on both the Mission Creek strand of the San Andreas fault (~215 yr) and the Coachella section (~125 yr) of the San Andreas fault.

The San Andreas Fault

1993 ◽  
Author(s):  
Sandra S. Schulz ◽  
Robert E. Wallace
Keyword(s):  
San Andreas Fault ◽  
San Andreas
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