Abstract

We studied the source processes of two large continental earthquakes, the 3 November 2002 Denali fault earthquake and the 14 November 2001 Kunlun fault earthquake, associated with strike-slip faulting along ancient sutures. We inverted teleseismic P waveforms using a pulse-stripping method for multiple time windows with different focal mechanisms and derived composite source models. According to our results, the 2002 Denali fault earthquake began with initial thrusting (Mw 7.3) along a 40-km-long segment of the north-northwest-dipping Susitna Glacier fault and later ruptured a 300-km-long segment along the Denali and Totschunda faults with a right-lateral strike-slip mechanism (Mw 7.7). In contrast, the 2001 Kunlun fault earthquake nucleated near an extensional step-over with a subevent pair consisting of 30-km-long strike-slip (Mw 6.9) event and 40-km-long normal (Mw 6.8) faulting event and later ruptured a 350-km-long segment along the Kunlun fault with a left-lateral strike-slip mechanism (Mw 7.7). Both earthquakes propagated primarily unilaterally to the east and released most of their energy along slip patches (asperities) far from the hypocenter locations. We find that both the Denali fault and Kunlun fault earthquakes had high-average rupture velocities of 3.2 km/sec and 3.4 km/sec, respectively. We also compared the source properties of these two earthquakes with other strike-slip earthquakes. For scaling purposes, large strike-slip earthquakes were classified as interplate, oceanic intraplate, or continental intraplate events. By using this classification the Denali fault and Kunlun fault earthquakes have an interplate signature that suggests overall weak faulting.

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