Field observations and logs from the Rose Hip trench exposure across a north-facing scarp within the Seattle Fault Zone, southern Bainbridge Island, Washington

Stephen J. Angster; Brian L. Sherrod; Wes Johns; Jessie K. Pearl

doi:10.3133/sim3520

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Field observations and logs from the Rose Hip trench exposure across a north-facing scarp within the Seattle Fault Zone, southern Bainbridge Island, Washington

Stephen J. Angster·Brian L. Sherrod·Wes Johns·Jessie K. Pearl

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Abstract

The Seattle Fault Zone is an approximately 70-km-long, east-west-trending zone of south-dipping blind reverse faults within the Puget lowland region in Washington. Because of the proximity, the Seattle Fault Zone poses a significant earthquake hazard to the Puget sound and Seattle metropolitan regions. We present preliminary mapping and trench-site information from a paleoseismic investigation across a newly identified active fault scarp located within the hanging wall of the Seattle Fault Zone on southern Bainbridge Island, Washington. The trench exposed monoclinally folded Miocene bedrock, fractured and faulted glacial-related deposits, and laminated lacustrine deposits capped by slope-derived colluvium. The observations from this investigation record late Pleistocene to Holocene north-vergent folding and faulting along this new fault scarp.

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Scientific Investigations Map Report

Source-reported bounding extent: 47.53289178907738° to 47.757608280978104° latitude; -122.67488163265297° to -122.40034867558737° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Stephen J. Angster, Brian L. Sherrod, Wes Johns, Jessie K. Pearl. 2024-06-11. Field observations and logs from the Rose Hip trench exposure across a north-facing scarp within the Seattle Fault Zone, southern Bainbridge Island, Washington. https://doi.org/10.3133/sim3520

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