Abstract

Code amplitude decay rates as a function of lapse time (time measured from the origin time) for two moderate size Alaskan earthquakes are related to their known values of seismic moments. This relation is then used to compute seismic moments from coda-wave data for a selected group of small earthquakes located in the greater Fairbanks, Alaska, seismic zone. The computed values of moment appear to be consistent with the local magnitudes. Next, with the moment and magnitude data, an empirical moment-magnitude relation is obtained for central and southcentral Alaska. This relation is similar to those for central and northern California proposed by others. Computation for Q values in the frequency (f) band 1.03 to 1.5 Hz for central and southcentral Alaska with local coda-wave data yielded values in the range from about 160 to 290. The minimum of Q(f) appears to be in the frequency interval from 0.5 to 1.5 Hz. Moreover, Q values (f = 1 Hz) in the above range have been recently reported by others for areas in western United States having similar tectonic history as the Alaskan study area.

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