NONCHARACTERISTIC NORMAL FAULTING SURFACE RUPTURES FROM THE GULF OF CORINTH, GREECE

The February 24-25th, 1981, Gulf of Corinth earthquakes, ruptured only the western end of the South Alkyonides Fault Segment (SAFS) whose le ngth has been confirmed by study of spatial variations in fault throw, footwall uplift and hangingwall subsidence, and fault slip directions : this contrasts with what we would expect of the surface ruptures fro m characteristic earthquakes. Specifically, the eastern end of the 198 1 ruptures, where the smallest coseismic throws and northwest plunging coseismic slip vectors were reported, coincides with the position whe re the greatest values for uplift/subsidence and fault throws exist al ong the SAFS, and where fault slip data record northwest, north and no rtheast plunging slip vectors from previous earthquakes. The SAFS appe ars to have grown by recurrence of noncharacteristic earthquakes. A ne w model of earthquake recurrence is proposed which accounts for ruptur es that are shorter than the host fault segments, spatial variations i n cumulative throw and fault slip directions along a fault segment, an d temporal variation in the coseismic slip direction for successive ea rthquakes. The model implies that recurrence intervals vary both along single fault segments and with time for single localities. Thus palae oseismological data from one site may not constrain earthquake recurre nce at another along the same fault segment or fault slip rates over t ime periods containing numerous earthquake cycles.