Frequency-moment distribution of earthquakes in the Aleutian Arc: A test of the characteristic earthquake model

Abstract

Abstract The frequency-moment distribution of earthquakes is derived for discrete regions of the entire Aleutian Arc, both for segments which have ruptured in historic times and those regions which have been identified as seismic gaps. This distribution is then compared to the moment of the largest event in the respective region, or for gaps, the largest event which is likely to occur based on a plate-kinematic model of accumulated moment. Data for this study are based upon three data sources. Instrumental data are utilized for the 18 yr subsequent to the establishment of the World Wide Standardized Seismograph Network (WWSSN). Data for events of magnitude 7 and greater have been carefully collected and are presumed to be complete for the time period 1899 to present. The last data set is comprised of the largest event in each region, either an actual earthquake or the moment estimate based on current plate slip rates. Data were normalized to the recurrence time of the largest event in the respective zone. In all cases, the data seriously underestimate the largest moment event, indicating that a characteristic earthquake model is appropriate for individual fault zones. However, if the data are combined for the entire arc, the largest event is closely predicted. This indicates that a b-value model may be utilized only for regions in which there is a distribution in the size of earthquake producing faults.