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TitleTsunami inundation scenarios for Oregon
AuthorPriest, G R; Witter, R C; Zhang, Y J; Wang, K; Goldfinger, C; Stimely, L L; English, J; Pickner, S G; Hughes, K L B; Wille, T E; Smith, R L
Source 2013.
Alt SeriesEarth Sciences Sector, Contribution Series 20130211
PublisherOregon Department of Geology and Mineral Industries
Mediapaper; on-line; digital
ProgramAssessing Earthquake Geohazards, Public Safety Geoscience
Links Hinchey" title="Online - En ligne">Online - En ligne
AbstractThis digital data release is for seven tsunami inundation scenarios for the entire Oregon coast in the form of polygons (ArcGIS shapefiles). These scenarios are depicted on published Oregon Department of Geology and Mineral Industries (DOGAMI) tsunami inundation maps (TIM¿s). The hydrodynamic computer model, SELFE, is used to simulate tsunami generation, propagation and maximum inundation for five Cascadia subduction zone (CSZ) earthquake sources (SM1, M1, L1, XL1, XXL1) and two Mw (moment magnitude) 9.2 Alaska earthquake sources: the historical maximum that struck in 1964 (AK64) and a hypothetical maximum (AKMax) with highly efficient focusing of tsunami energy at the Oregon coast. Inundation for XXL1 and the AKMax are the recommended evacuation zones for local and distant tsunamis, respectively. Model CSZ slip is estimated primarily from size and time between deposits left behind by submarine sand and silt slurries (turbidites) triggered by CSZ earthquakes. Relative CSZ tsunami heights at each latitude scale directly to local peak fault slip calculated from model time intervals over which the CSZ accumulates slip that is released in earthquakes as follows: Sm1 = 300 yrs, M1 = 425-525 yrs, L1 = 650-800 yrs, XL1 = 1,050-1,200 yrs, XXL1 = 1200 yrs. All five CSZ sources partition fault slip from the CSZ megathrust to an offshore splay fault with an average eastward inclination of ~30°. Based on a logic tree summarizing sources of variability, the five CSZ inundations cover the following percentages of potential variability in CSZ tsunami inundation: Sm1 = 26%, M1 = 79%, L1 = 95%, XL1 = 98%, XXL1 = 100%. Model tide for all seven scenarios is assumed to be Mean Higher High Water (MHHW), varying south to north from 2.07 m (6.8 ft) to 2.71 m (8.9 ft) NAVD88 (North American Vertical Datum of 1988). Tsunami simulations utilize unstructured computational grids constructed from detailed bathymetric and topographic data, particularly lidar. Spacing between computational grid points, a measure of the precision of the inundation boundaries, is generally less than 10 m in populated areas and at critical shoreline features such as jetties.
Summary(Plain Language Summary, not published)
Over the past few years, Oregon Department of Geology and Mineral Industries (DOGAMI) has developed a suite of tsunami inundation models for a number of assumed Cascadia megathrust rupture scenarios, and used them as basis for probablistic tsunami hazard assessment for the Oregon coast. The rupture source models are based on the best knowledge of geology, geodynamics, earthquake physics, and Cascadia earthquake history. The tsunami models are developed with an advanced computer code of hydrodynamics. DOGAMI is now releasing the digital files of the model-predicted inundation scenarios that all have been published in peer-reviewed journals. This report, to accompany the digital files, briefly summarizes the science and analytical methods involved.