The research team is studying the degree to which fault loading and strain release rates are constant (or non-constant) in time and space. Their work in addressing this fundamentally important issue focuses on the generation of fault slip rates at a variety of time scales a long the North and East Anatolian faults in Turkey. These faults are particularly attractive targets for the proposed research because of the relative structural simplicity of the Anatolia-Eurasia-Arabia plate boundary in Turkey. Specifically, geodetic and geologic data suggest that in central and eastern Turkey almost all plate boundary strain is accommodated by slip on these two faults. The investigators are focusing their efforts on what increasingly appears to be a critical time scale of observation - the time range between the temporally irregular strain release documented by historical and paleoearthquake data, and longer time scales over which fault slip rates appear to be relatively constant. By using cosmogenic nuclide dating of offset geomorphic features, a technique that yields the duration of time that a geomorphic surface has been exposed to cosmic rays at the earth's surface, they will determine slip rates at eight or more sites along these two faults at a variety of time scales ranging from approximately 1.500 to greater than 10,000 years. Their results, in combination with ongoing paleoseismolgic analyses of these faults by U.S., Turkish, and Japanese researchers, will allow determination of the variability of strain release in time and space within the Anatolia-Eurasia-Arabia plate boundary. These data, in turn, will provide basic constraints necessary for realistic geodynamic models of fault loading mechanisms. Equally importantly, the data from the relatively simple plate boundary in Turkey will provide an important point of comparison with similar data from more mechanically complex plate boundaries (e. g., the Pacific-North America plate boundary in California).
