Long-period source characteristics of the great 1964 Alaska earthquake

The 1964 Alaska earthquake is the second-largest earthquake ever recorded instrumentally. Current estimates of the long-period source characteristics of this earthquake, including the earthquake size and faulting geometry and the timing and distribution of moment release, date from the 1970s. All of these estimates were made before the development of modern methods of seismogram synthesis and moment-tensor determination. The occurrence of the 26 December, 2004 Sumatra-Andaman Islands earthquake (MW 9.2) has returned attention to the state of our knowledge about the 1964 Alaska earthquake, as the Alaska earthquake presents the most natural target for comparison. The proposed research will make use of existing hand-digitized, high-quality surface-wave seismograms from the 1964 mainshock in an inversion for the earthquake moment tensor, centroid location and depth, and centroid time; effects of Earth's lateral velocity heterogeneity will be accounted for in the inversion. Owing to the very large size of the 1964 earthquake, and to the fact that the available data correspond to late-arriving surface-wave orbits, several experiments will be carried out to validate the results obtained. Results obtained from this study will also be of direct use for comparative studies of other large earthquakes, including the 2004 Sumatra-Andaman Islands earthquake. In addition, the proposed effort to archive the available, hand-digitized data from the 1964 earthquake is anticipated to benefit researchers interested in both earthquake dynamics and Earth structure. The research will support an early-career scientist. At the conclusion of the project, the data used will be permanently archived to make them available for future use by other researchers.