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Source process of the 3 November 2002 Denali fault earthquake (central Alaska) from teleseismic observations

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2003-06-25
Özacar, Atilla Arda
Beck, SL
Christensen, DH
[1] The November 3, 2002 Denali fault earthquake, which is the largest inland event ever recorded in central Alaska, occurred along an arcuate segment of the right-lateral strike-slip Denali fault. We use first-motion P wave polarities and inversions of teleseismic P waveforms for a fixed focal mechanism to constrain the rupture process. We find clear evidence for a substantial reverse component near the hypocenter at the beginning of the rupture. Twenty-five seconds later, rupture propagated unilaterally to the east on a strike-slip fault and released most of the seismic moment along an asperity located 170 km east of the hypocenter with a maximum slip of 8 m. This earthquake had a duration of similar to120 s and ruptured more than 300 km in length. Correlation with gravity anomalies suggests a relation between moment distribution and physical properties of subsurface rock units that may support a weaker middle fault segment marked by fewer aftershocks.