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TitleSimulated tsunami inundation for a range of Cascadia megathrust earthquake scenarios at Bandon, Oregon, USA
AuthorWitter, R C; Zhang, Y J; Wang, K; Priest, G R; Goldfinger, C; Stimely, L; English, J T; Ferro, P A
SourceGeosphere vol. 9, no. 6, 2013 p. 1783-1803,
Alt SeriesEarth Sciences Sector, Contribution Series 20120390
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf
AreaBrandon; Oregon; United States
Lat/Long WENS-124.5000 -124.0000 43.0000 42.0000
Lat/Long WENS-124.2500 -124.2500 43.1667 42.8333
Subjectsmarine geology; geophysics; tsunami; earthquakes; earthquake studies; earthquake mechanisms; health hazards; geological hazards
Illustrationslocation maps; tables; profiles; plots
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
LinksOnline - En ligne
AbstractCharacterizations of tsunami hazards along the Cascadia subduction zone hinge on uncertainties in megathrust rupture models used for simulating tsunami inundation. To explore these uncertainties, we constructed 15 megathrust earthquake scenarios using rupture models that supply the initial conditions for tsunami simulations at Bandon, Oregon. Tsunami inundation varies with the amount and distribution of fault slip assigned to rupture models, including models where slip is partitioned to a splay fault in the accretionary wedge and models that vary the updip limit of slip on a buried fault. Constraints on fault slip come from onshore and offshore paleoseismological evidence. We rank each rupture model using a logic tree that evaluates a model's consistency with geological and geophysical data. The scenarios provide inputs to a hydrodynamic model, SELFE, used to simulate tsunami generation, propagation, and inundation on unstructured grids with <5 - 15 m resolution in coastal areas. Tsunami simulations delineate the likelihood that Cascadia tsunamis will exceed mapped inundation lines. Maximum wave elevations at the shoreline varied from ~4 m to 25 m for earthquakes with 9 - 44 m slip and Mw 8.7 - 9.2. Simulated tsunami inundation agrees with sparse deposits left by the A.D. 1700 and older tsunamis. Tsunami simulations for large (22 - 30 m slip) and medium (14 - 19 m slip) splay fault scenarios encompass 80% - 95% of all inundation scenarios and provide reasonable guidelines for land-use planning and coastal development. The maximum tsunami inundation simulated for the greatest splay fault scenario (36 - 44 m slip) can help to guide development of local tsunami evacuation zones.