Buried Aseismic Slip and Off‐Fault Deformation on the Southernmost San Andreas Fault Triggered by the 2010 El Mayor Cucapah Earthquake Revealed by UAVSAR

Parker, Jay; Donnellan, Andrea; Bilham, Roger; Ludwig, Lisa Grant; Wang, Jun; Pierce, Marlon; Mowery, Nicholas; Jänecke, Susanne U.

doi:10.1029/2021ea001682

Cited by 2 publications

(1 citation statement)

References 48 publications

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“…InSAR data also indicate that slip on the southern section of the SHF occurs in a zone narrower than ∼100 m (Figure S3 in Supporting Information ), much more localized compared to slip on the northern section. It was suggested that continuous across‐fault variations in surface displacements due to fault slip might result from a strong shallow layer resisting the propagation of slip to the Earth's surface, resulting in a “surface locking depth” (Brooks et al., 2017; Parker et al., 2021). However, given the low mechanical strength of near‐surface sediments, a more plausible explanation is that the effective width of the shear zone reflects distributed failure within the fault damage zone with depth comparable to (or greater than) its width (Fialko et al., 2002; Lindsey, Fialko, et al., 2014).…”

Section: Evolution Of Fault Slip During the 2023 Ssementioning

confidence: 99%

Characteristic Slow‐Slip Events on the Superstition Hills Fault, Southern California

Vavra,

Fialko,

Rockwell

et al. 2024

Geophysical Research Letters

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The Superstition Hills Fault (SHF) exhibits a rich spectrum of slip modes, including M 6+ earthquakes, afterslip, quasi‐steady creep, and both triggered and spontaneous slow slip events (SSEs). Following 13 years of quiescence, creepmeters recorded 25 mm of slip during 16–19 May 2023. Additional sub‐events brought the total slip to 41 mm. The event nucleated on the northern SHF in early‐May and propagated bi‐laterally at rates on the order of kilometers per day. Surface offsets reveal a bi‐modal slip distribution, with slip on the northern section of the fault being less localized and lower amplitude compared to the southern section. Kinematic slip models confirm systematic variations in the slip distribution along‐strike and with depth and suggest that slip is largely confined to the shallow sedimentary layer. Observations and models of the 2023 SSE bear a strong similarity to previous slip episodes in 1999, 2006, and 2010, suggesting a characteristic behavior.

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Section: Evolution Of Fault Slip During the 2023 Ssementioning

confidence: 99%

Characteristic Slow‐Slip Events on the Superstition Hills Fault, Southern California

Vavra,

Fialko,

Rockwell

et al. 2024

Geophysical Research Letters

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Hematite accommodated shallow, transient Pleistocene slow slip in the exhumed southern San Andreas fault system, California, USA

DiMonte

Ault

Hirth

et al. 2022

Geology

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Slow slip is part of the earthquake cycle, but the processes controlling this phenomenon in space and time are poorly constrained. Hematite, common in continental fault zones, exhibits unique textures and (U-Th)/He thermochronometry data patterns reflecting different slip rates. We investigated networks of small hematite-coated slip surfaces in basement fault damage of exhumed strike-slip faults that connect to the southern San Andreas fault in a flower structure in the Mecca Hills, California, USA. Scanning electron microscopy shows these millimeter-thick surfaces exhibit basal hematite injection veins and layered veinlets comprising nanoscale, high-aspect-ratio hematite plates akin to phyllosilicates. Combined microstructural and hematite (U-Th)/He data (n = 64 new, 24 published individual analyses) record hematite mineralization events ca. 0.8 Ma to 0.4 Ma at <1.5 km depth. We suggest these hematite faults formed via fluid overpressure, and then hematite localized repeated subseismic slip, creating zones of shallow off-fault damage as far as 4 km orthogonal to the trace of the southern San Andreas fault. Distributed hematite slip surfaces develop by, and then accommodate, transient slow slip, potentially dampening or distributing earthquake energy in shallow continental faults.

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Buried Aseismic Slip and Off‐Fault Deformation on the Southernmost San Andreas Fault Triggered by the 2010 El Mayor Cucapah Earthquake Revealed by UAVSAR

Cited by 2 publications

References 48 publications

Characteristic Slow‐Slip Events on the Superstition Hills Fault, Southern California

Characteristic Slow‐Slip Events on the Superstition Hills Fault, Southern California

Hematite accommodated shallow, transient Pleistocene slow slip in the exhumed southern San Andreas fault system, California, USA

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