Margin-wide geological and geophysical synthesis to understand the recurrence and hazards of great subduction zone earthquakes in Cascadia

The Cascadia Subduction Zone, located in the U.S. Pacific Northwest and southwestern British Columbia, has hosted magnitude ≥8.0 megathrust earthquakes in the geologic past, a future earthquake is imminent, and the potential impacts could cripple the region. Subduction zone earthquakes represent some of the most devastating natural hazards on Earth.

Despite substantial knowledge gained from decades of geoscience research, the size and frequency of Cascadian earthquakes remain controversial, as do the physics of earthquake rupture, the effects of earthquake shaking, and the effect of resultant tsunamis. This translates into major uncertainties in earthquake hazard assessments that can lead to ineffective preparedness measures. Reducing uncertainties in earthquake hazards along Cascadia requires addressing three fundamental questions in subduction zone science: (1) To what extent does the earthquake-cycle model apply to Cascadia, and to great earthquake recurrence more broadly? (2) How do megathrust earthquakes rupture and radiate? (3) How does the record of secondary coseismic geologic effects inform Cascadia Subduction Zone earthquake timing, magnitude, and hazards?

We will address the questions posed above by compiling and integrating available data, objectively assessing dataset uncertainties, and employing a highly multidisciplinary suite of integrative activities. To meet our goals, we have enlisted experts in tectonics, geophysics, crustal structures, landslides, sedimentology, paleoseismology, land-level changes, geodesy, mantle and crustal rheology, earthquake rupture dynamics, disaster management, and risk communication into our Powell Center working group.

Publications:

Staisch, L.M., 2024, Sensitivity testing of marine turbidite age estimates along the Cascadia subduction zone: Bulletin of the Seismological Society of America, https://doi.org/10.1785/0120230252.

Staisch, L.M., Walton, and R. Witter (2019), Addressing Cascadia Subduction Zone great earthquake recurrence, Eos, 100, https://doi.org/10.1029/2019EO127531. Published on 02 July 2019.

Data Release:
Staisch, L.M., Witter, R.C., Watt, J.T., Grant, A.R., Walton, M.A., Brothers, D., Davis, E., Dura, C., Engelhart, S., Enkin, R., Garrison-Laney, C.E, Goldfinger, C., Hamilton, T., Hawkes, A., Hill, J.C., Hong, I.J., Jaffe, B.E., Kelsey, H., Lahusen, S.R, La Selle, S.M, Nelson, A.R, Nieminski, N.M, Padgett, J.S, Patton, J., Pearl, J.K, Pilarczyk, J., Sherrod, B., and Stanton, K., 2024, Compiled onshore and offshore paleoseismic data along the Cascadia Subduction zone: U.S. Geological Survey data release, https://doi.org/10.5066/P13OJQYW.

Principal Investigator(s):
Lydia M Staisch (Geology, Minerals, Energy, and Geophysics Science Center)
Janet Tilden Watt (Pacific Coastal and Marine Science Center)
Jonathan P Perkins (Geology, Minerals, Energy, and Geophysics Science Center)
Robert C Witter (Alaska Science Center)

Participants:
Maureen Walton (USGS)
Joan Gomberg (USGS)
Erin Wirth (USGS)
Fred Pollitz (USGS)
Brian Sherrod (USGS)
Ray Wells (USGS)
Chris Goldfinger (Oregon State University)
Tina Dura (Virginia Tech)
Simon Engelhart (University of Rhode Island)
Ann Morey (Oregon State University)
Anne Trehu (Oregon State University)