Paleoseismic investigations of Quaternary active faults in the forearc and backarc of the central Pacific Northwest

  • 27 Sep 2022
  • 7:00 PM
  • Online and in-person at Central Oregon Community College, SCI 190

Ashley Streig

Portland State University

Historically, few damaging earthquakes have occurred in the Pacific Northwest region of the United States, although the region overlies the seismically active Cascadia Subduction Zone. Earthquake resilience efforts here have largely focused on the offshore Cascadia Subduction Zone and its potential for M 9 earthquakes. Damaging earthquakes on upper-plate faults, such as the Seattle fault (WA) or the Gales Creek fault (OR), are also a poorly understood threat to the region. Few active faults have been identified onshore in Oregon, but in the last decade new laser terrain imagery (lidar) has revealed widespread and previously unknown active faults distributed across the landscape.

Our research seeks to improve our understanding of crustal deformation through targeted tectonic-geomorphic and paleoseismic investigations of Holocene active faults in the forearc and backarc of the central Pacific Northwest, where the rates and timing of faulting during the past 30,000 years remain largely unconstrained. Data from these ongoing studies will allow us to evaluate the persistence of rigid to semi-rigid block boundaries determined from GPS velocity data, and will improve our understanding of complex crustal accommodation of Pacific Northwest rotation on Holocene to late-Pleistocene time.

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Central Oregon Geoscience Society

P.O. Box 2154,  Bend, Oregon 97709

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