Accelerating Seismic Moment Release and Outer-Rise Compression - Possible Precursors to the Next Great Earthquake in the Alaska Peninsula Region

The moment release rate in the Kodiak Island (KI) segment increased prior to the great 1964 Prince William Sound earthquake (M(w) = 9.2). Starting in 1983 the moment release rate in the Shumagin Island (SI) segment shows a similar increase. In July 1990, an outer-rise reverse earthquake showed are-normal compression at a depth of 42 km seaward of the Alaska Peninsula (AP) segment. Because accelerating moment release and are-normal compression have both been proposed as precursors to large and great earthquakes, we suggest this is evidence that the SI-AP region is nearing the end of the seismic cycle between large thrust earthquakes.