THE 1971 MAY 12 BURDUR EARTHQUAKE SEQUENCE, SW TURKEY - A SYNTHESIS OF SEISMOLOGICAL AND GEOLOGICAL OBSERVATIONS

It is now widely accepted that the rapid extension observed in western Turkey is mainly accommodated by large active normal faults which control the geomorphology. The NE-SW trending Burdur, Acigol and Baklan basins bounded by large faults form a system of half-graben whose orientation is evident in both the topography and the tilting of Neogene sediments adjacent to them. We used long-period P- and SH-waveforms to determine the source parameters of the two largest earthquakes of the 1971 May 12 sequence that occurred in the Burdur region. The main shock was followed by many aftershocks, which were distributed in a broad zone elongated NE-SW, parallel to the long axes of the basins in the region. Documented surface breaks of the 1971 event suggest that the northwest-dipping faults along the southern margin of the Burdur Basin are those which moved. Well-exposed fault planes are found dominantly to the south of Burdur lake; the surface dips of these faults are greater than that of the NW-dipping nodal plane obtained for the main shock. Combined seismological and geological observations suggest that these faults have listric geometries.