Coexisting seismic behavior of transform faults revealed by high-resolution bathymetry

Geology
By: , and 

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Abstract

Transform faults are known to have anomalously low rates of seismicity, but no direct observations reveal why this is the case. We use new, autonomous underwater vehicle high-resolution seafloor mapping to image the morphology of and offsets along transform fault segments in the Gulf of California. Fault splays display a varied history of activation and deactivation of individual fault strands over time, not unlike those mapped onshore or imaged within the bathymetry of the Queen Charlotte-Fairweather and the Palos Verdes faults of offshore western Canada and Southern California. A series of six identically offset depositional fans evidence 21–23 meters of slip along the main transform fault, which could not have been produced by a single earthquake. Rather, the lack of smaller-magnitude offsets indicates synchronous deposition and an absence of multiple slope failure-inducing earthquakes, thus providing the first direct evidence that creep and earthquakes occur at different times in the slip history of a given transform fault segment.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Coexisting seismic behavior of transform faults revealed by high-resolution bathymetry
Series title Geology
DOI 10.1130/G46663.1
Edition Online First
Year Published 2020
Language English
Publisher Geological Society of America
Contributing office(s) Geosciences and Environmental Change Science Center
Country Canada, United States, Mexico