Buried Aseismic Slip and Off-Fault Deformation on the Southernmost San Andreas Fault triggered by the 2010 El Mayor Cucapah Earthquake revealed by UAVSAR Journal Article uri icon

Overview

abstract

  • ; We use UAVSAR interferograms to characterize fault slip, triggered by; the Mw 7.2 El Mayor-Cucapah earthquake on the southernmost San Andreas; Fault in the Coachella Valley providing comprehensive maps of landscape; change that complement; in situ; measurements. Creepmeters and; geological mapping of fault offsets on Durmid Hill recorded 4 mm and 8; mm of average triggered slip respectively on the fault, in contrast to; radar views that reveal significant off-fault dextral deformation; averaging 20 mm. Unlike slip in previous triggered slip events on the; southernmost San Andreas fault, dextral shear in 2010 is not confined to; transpressional hills in the Coachella valley. Edge detection and; gradient estimation applied to the 50-m-sampled interferogram data; identify the location (to 20 m) and local strike (to < 4°) of; secondary surface ruptures. Transverse curve fitting applied to these; local detections provides local estimates of the radar-projected dextral; slip and a parameter indicating the transverse width of the slip, which; we equate with the depth of subsurface shear. These estimates are; partially validated by fault-transverse interferogram profiles generated; using the web-based UAVSAR tool of GeoGateway, and appear consistent for; radar-projected slip greater than about 5 mm. An unexpected finding is; that creep and triggered slip on the San Andreas fault terminate in the; shallow subsurface below a surface shear zone that resists the simple; expression of aseismic fault slip. We introduce the notion of a surface; locking depth above which fault slip is manifest as distributed shear,; and evaluate its depth as 6-27 m.;

publication date

  • February 1, 2021

has restriction

  • hybrid

Date in CU Experts

  • May 18, 2023 1:27 AM

Full Author List

  • Parker J; Bilham R; Donnellan A; Ludwig LG; Pierce M; Wang J; Mowery N

author count

  • 7

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