Dense geophysical observations reveal a triggered, concurrent multi-fault rupture at the Mendocino Triple Junction

William L. Yeck; David R. Shelly; Dara Elyse Goldberg; Kathryn Zerbe Materna; Paul S. Earle

doi:10.1038/s43247-023-00752-2

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Dense geophysical observations reveal a triggered, concurrent multi-fault rupture at the Mendocino Triple Junction

William L. Yeck·David R. Shelly·Dara Elyse Goldberg·Kathryn Zerbe Materna·Paul S. Earle

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Abstract

A central question of earthquake science is how far ruptures can jump from one fault to another, because cascading ruptures can increase the shaking of a seismic event. Earthquake science relies on earthquake catalogs and therefore how complex ruptures get documented and cataloged has important implications. Recent investments in geophysical instrumentation allow us to resolve increasingly complex, multi-fault ruptures for even moderate-sized earthquakes. We combine dense seismic and geodetic measurements to reveal an enigmatic rupture in late 2021 at the Mendocino Triple Junction in northern California. We show that rupture was dynamically triggered, yet concurrent, on two distinct faults roughly 30 km apart. Thus, this rupture combines features of complex ruptures usually considered to be single earthquakes, and triggered ruptures considered as multiple earthquakes. This event illustrates that moderate-sized earthquakes can exhibit similar complexity to that more commonly documented for large earthquakes.

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Nature Communications Earth and Environment Article

Source-reported bounding extent: 39.87808437058166° to 41.014611349173805° latitude; -124.51940881271767° to -123.6408804704962° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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William L. Yeck, David R. Shelly, Dara Elyse Goldberg, Kathryn Zerbe Materna, Paul S. Earle. 2023-03-25. Dense geophysical observations reveal a triggered, concurrent multi-fault rupture at the Mendocino Triple Junction. https://doi.org/10.1038/s43247-023-00752-2

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