Seismicity trends and potential for large earthquakes in the Alaska-Aleutian region

The 1964 Prince William Sound earthquake: Joint inversion of tsunami and geodetic data

“…seismic and tsunami hazards in Alaska requires that we examine closely the slip distribution of the 1964 earthquake. Recent analyses of seismicity and seismic recurrence along the Alaska-Aleutian subduction zone show that the Prince William Sound and Kodiak blocks are separate plate segments with differing rupture probabilities[Nishenko, 1991;Bufe et al, 1994]. Indeed, the historic record suggests that the Kodiak segment has ruptured both independently and together with segments further to the west along the Alaska Peninsula[Davies et al, 1981].The results of the joint inversion do support the division of the 1964 rupture zone into two different segments.…”

Transition from locked to creeping subduction in the Shumagin region, Alaska

“…That quake may have ruptured from the eastern edge of the Shumagins to somewhere west of the Shumagin Islands, but not as far as Sanak Island [Boyd et al, 1988]. Other moderate sized earthquakes have been attributed to rupturing a portion of the plate interface in the Shumagin segment, including an M s 7.5 in 1948 and an M s 7.1 in 1993 [Bufe et al, 1994]. No great earthquakes are known to have occurred in the Shumagin segment, and no large earthquakes are known from the western portion of the Shumagin segment.…”

Intermediate-term earthquake prediction.

“…The last two patterns are not mutually exclusive, since they take place in different areas and time intervals. Less substantiated so far but sufficiently well defined are the following premonitory phenomena: increase of the range of spatial correlation in the earthquake flow (49), and log-periodic variations of the earthquake flow on the background of its exponential rise (16,46,50 Analysis of Model-Generated Seismicity. Analysis of modelgenerated seismicity confirms that the algorithms described above tap rather general symptoms of subcritical state.…”

“…Seismic flux is defined as a spatiotemporal distribution of seismicity smoothed by the magnitude-dependent Gaussian kernels (41 (42)(43)(44), the reversal of territorial distribution of seismicity that is activation of relatively quiet faults and quiescence on relatively active faults (45), the rise of seismic activity (10,15,23,46), and the seismic quiescence (17,47,48). The last two patterns are not mutually exclusive, since they take place in different areas and time intervals.…”