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Insights into active deformation of southern Prince William Sound, Alaska from new high-resolution seismic data

FINN, S.P., Boise State University, Boise/ID/USA, sfinn@cgiss.boisestate.edu; LIBERTY, L.M., Boise State University, Boise/ID/USA, lml@cgiss.boisestate.edu; HAEUSSLER, P.J., USGS, Anchorage/AK/USA, pheuslr@usgs.gov; PRATT, T.L., USGS, School of Oceanography, UW, Seattle/WA/USA, tpratt@ocean.washington.edu

We collected ~400km of multi-channel seismic data in August 2009 in eastern and southern Prince William Sound, Alaska, for identifying and characterizing active faults. Preliminary processing show at least three seismic facies that we infer are late Quaternary and younger sediments, which are less than a few hundred meters thick. We found numerous high-angle faults, particularly in the southern part of the Sound. Beneath Montague Strait, we observe a zone of uplift and faulting broader than what occurred in the 1964 M9.2 earthquake. Additionally, growth faulting and the shallow depth to Tertiary rocks suggest reactivation of older structures and long-term regional uplift. Within eastern Prince William Sound, lineations mapped on land and sea floor are also related to active faulting, suggesting significantly greater deformation related to megathrust earthquakes in the area than previously published. Additional analyses of newly acquired data, in combination with existing surveys should help improve seismic hazard assessments and tectonic models for the area.

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Last Modified: 2011 Aug 10

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