Motion on the Kaparelli fault (Greece) prior to the 1981 earthquake sequence determined from ³⁶Cl cosmogenic dating

Abstract

ABSTRACT In February and March 1981, three successive destructive earthquakes occurred at the eastern end of the Gulf of Corinth. The third shock (March, 4, Ms ≈ 6.4) ruptured the Kaparelli fault. About 40 cm of a limestone fault scarp was exhumed by the earthquake. Each major prehistoric earthquake has added new surface to this cumulative scarp exposing fresh material to cosmic‐ray bombardment. Using 36 Cl cosmic ray exposure dating we have obtained the continuous exposure history for this 4–5‐m‐high limestone surface at two sites about 50 m apart. The results suggest that the Kaparelli fault has ruptured three times prior to 1981 at 20 ± 3 ka, 14.5 ± 0.5 ka and 10.5 ± 0.5 ka with slip amplitudes between 0.6 m and 2.1 m. The Kaparelli fault appears to have been inactive for 10 thousand years prior to the 1981 event.