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dc.contributor.authorHreinsdottir, Sigrun
dc.date.accessioned2018-07-11T01:04:08Z
dc.date.available2018-07-11T01:04:08Z
dc.date.issued2005
dc.identifier.urihttp://hdl.handle.net/11122/8777
dc.descriptionThesis (Ph.D.) University of Alaska Fairbanks, 2005
dc.description.abstractGPS geodetic measurements are used to study two major earthquakes, the 2001 MW 7.7 El Salvador and 2002 MW 7.9 Denali Fault earthquakes. The 2001 MW 7.7 earthquake was a normal fault event in the subducting Cocos plate offshore El Salvador. Coseismic displacements of up to 15 mm were measured at permanent GPS stations in Central America. The GPS data were used to constrain the location of and slip on the normal fault. One month later a MW 6.6 strike-slip earthquake occurred in the overriding Caribbean plate. Coulomb stress changes estimated from the M W 7.7 earthquake suggest that it triggered the MW 6.6 earthquake. Coseismic displacement from the MW 6.6 earthquake, about 40 mm at a GPS station in El Salvador, indicates that the earthquake triggered additional slip on a fault close to the GPS station. The MW 6.6 earthquake further changed the stress field in the overriding Caribbean plate, with triggered seismic activity occurring west and possibly also to the east of the rupture in the days to months following the earthquake. The MW 7.9 Denali Fault earthquake ruptured three faults in the interior of Alaska. It initiated with a thrust motion on the Susitna Glacier fault but then ruptured the Denali and Totschunda faults with predominantly right-lateral strike-slip motion unilaterally from west to east. GPS data measured in the two weeks following the earthquake suggest a complex coseismic rupture along the faults with two main regions of moment release along the Denali fault. A large amount of additional data were collected in the year following the earthquake which greatly improved the resolution on the fault, revealing more details of the slip distribution. We estimate a total moment release of 6.81 x 1020 Nm in the earthquake with a M W 7.2 thrust subevent on Susitna Glacier fault. The slip on the Denali fault is highly variable, with 4 main pulses of moment release. The largest moment pulse corresponds to a MW 7.5 subevent, about 40 km west of the Denali-Totschunda fault junction. We estimate relatively low and shallow slip on the Totschunda fault.
dc.subjectGeophysics
dc.subjectGeographic information science and geodesy
dc.subjectGeology
dc.titleCoseismic Deformation Of The 2001 El Salvador And 2002 Denali Fault Earthquakes From Gps Geodetic Measurements
dc.typeThesis
dc.type.degreephd
dc.identifier.departmentDepartment of Geology and Geophysics
dc.contributor.chairFreymueller, Jeffrey T.
refterms.dateFOA2020-01-24T15:08:50Z


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