Map of recently active traces of the Rodgers Creek Fault, Sonoma County, California

Hecker, Suzanne; Loar, Carolyn E. Randolph

doi:10.3133/sim3410

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…The faults themselves continue farther along strike. The Calaveras fault reaches farther southeast as it gets closer to the San Andreas fault (see Figure 1), the Rodgers Creek fault reaches farther northwest, as it transitions into the Healdsburg section northwest of Santa Rosa (Hecker & Randolph Loar, 2018), and the Northern Calaveras fault transitions into a complex zone of distributed faulting as it reaches farther north. Due to computational constraints, we truncate the along strike fault geometry.…”

Section: Fault Geometrymentioning

confidence: 99%

A Geology and Geodesy Based Model of Dynamic Earthquake Rupture on the Rodgers Creek‐Hayward‐Calaveras Fault System, California

et al. 2021

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The Hayward fault in California's San Francisco Bay area produces large earthquakes, with the last occurring in 1868. We examine how physics‐based dynamic rupture modeling can be used to numerically simulate large earthquakes on not only the Hayward fault, but also its connected companions to the north and south, the Rodgers Creek and Calaveras faults. Equipped with a wealth of images of this fault system, including those of its 3D geology and 3D geometry, in addition to inferences about its interseismic creep‐rate pattern and rock‐friction behavior, we use a finite‐element computer code to perform 3D dynamic earthquake rupture simulations. We find that the rock properties affect the locations and amount of slip produced in our simulated large earthquakes. Crucial factors that control rupture behavior in our modeling are the earthquake nucleation locations, the fault geometry, and the data that reveal where the fault system is creeping or locked. Our findings suggest that large Rodgers Creek‐Hayward‐Calaveras‐Northern Calaveras (RC‐H‐C‐NC) fault‐system earthquakes may result from dynamic rupture that starts in a locked part of the fault system, but is then stopped by the creeping parts, leading to high‐magnitude‐6 earthquakes; or, from dynamic rupture that starts in a locked part of the fault system, then cascades through some of the creeping parts, leading to magnitude‐7 earthquakes.

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Section: Fault Geometrymentioning

confidence: 99%

A Geology and Geodesy Based Model of Dynamic Earthquake Rupture on the Rodgers Creek‐Hayward‐Calaveras Fault System, California

et al. 2021

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“…The evolution of the northern Hayward and southern Rodgers Creek faults over the last 7 to 10 Ma has involved periods of extension, volcanism, and strike-slip basin development resulting in significant structural overprinting (McLaughlin et al, 2012). The most recently active strands of the Hayward-Rodgers Creek fault zone (Hecker & Randolph Loar, 2018;Watt, Ponce, et al, 2016) form a releasing bend that spans northern San Pablo Bay.…”

Section: Tectonic Settingmentioning

confidence: 99%

“…The Hayward-Rodgers Creek fault system extends approximately 140 km (Figure 1) from its intersection with the Calaveras fault in the south near the town of Alum Rock (Chaussard et al, 2015) to just north of Healdsburg (Hecker & Randolph Loar, 2018;Hecker et al, 2016). This fault system takes up substantial righ-lateral motion within the wide transform boundary between the Pacific and North American plates.…”

Section: Tectonic Settingmentioning

confidence: 99%

Marine Paleoseismic Evidence for Seismic and Aseismic Slip Along the Hayward‐Rodgers Creek Fault System in Northern San Pablo Bay

Watt

McGann

Takesue

et al. 2021

Geochem Geophys Geosyst

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Refining the earthquake history along the Hayward-Rodgers Creek fault zone is critical for estimating the earthquake hazard of and planning for future large earthquakes in the heavily populated San Francisco Bay area. Currently, the 30-year mean probability of a magnitude (M) > 6.7 earthquake on the combined Hayward-Rodgers Creek fault is the highest among faults in the region (Aagaard et al., 2016;Field et al., 2015). Understanding the behavior of an earthquake rupture when it encounters a fault bend requires in-depth knowledge of the fault geometry and connectivity, but also the earthquake history and the amount and distribution of creep, or aseismic slip, occurring along the fault system. Compilations of paleoseismic rupture histories along fault systems worldwide are used to characterize spatial-temporal patterns of large surface-rupturing earthquakes (e.g.,

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“…One such locality has been identified and targeted for future study. En echelon cracking was identified at an outcrop of the northern Rodgers Creek fault (Hecker & Randolph-Loar, 2018) that contains antigorite serpentinite gouge. A recently installed alignment array station (RCBP) set up nearby has recorded a small amount of fault creep thus far (McFarland et al, 2017).…”

Section: Future Research Plansmentioning

confidence: 99%

Serpentinite‐Rich Gouge in a Creeping Segment of the Bartlett Springs Fault, Northern California: Comparison With SAFOD and Implications for Seismic Hazard

2018

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An exposure of a creeping segment of the Bartlett Springs Fault (BSF), part of the San Andreas Fault system in northern California, is a ~1.5‐m‐wide zone of serpentinite‐bearing fault gouge cutting through Late Pleistocene fluvial deposits. The fault gouge consists of porphyroclasts of antigorite serpentinite, talc, chlorite, and tremolite‐actinolite, along with some Franciscan metamorphic rocks, in a matrix of the same materials. The Mg‐mineral assemblage is stable at temperatures above 250–300 °C. The BSF gouge is interpreted to have been tectonically incorporated into the fault from depths near the base of the seismogenic zone and to have risen buoyantly to the surface where it is now undergoing right‐lateral displacement. The ultramafic‐rich composition, frictional properties, and inferred mode of emplacement of the BSF serpentinitic gouge correspond to those of the creeping traces of the San Andreas Fault identified in the SAFOD (San Andreas Fault Observatory at Depth) drill hole. This suggests a common origin for creep at both locations. A tectonic model for the source of the ultramafic‐rich materials in the BSF is proposed that potentially could explain the distribution of creep throughout the northernmost San Andreas Fault system.

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Map of recently active traces of the Rodgers Creek Fault, Sonoma County, California

Cited by 3 publications

References 2 publications

A Geology and Geodesy Based Model of Dynamic Earthquake Rupture on the Rodgers Creek‐Hayward‐Calaveras Fault System, California

A Geology and Geodesy Based Model of Dynamic Earthquake Rupture on the Rodgers Creek‐Hayward‐Calaveras Fault System, California

Marine Paleoseismic Evidence for Seismic and Aseismic Slip Along the Hayward‐Rodgers Creek Fault System in Northern San Pablo Bay

Serpentinite‐Rich Gouge in a Creeping Segment of the Bartlett Springs Fault, Northern California: Comparison With SAFOD and Implications for Seismic Hazard

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