Recognition of past earthquakes along the Sparta fault (Peloponnesus, southern Greece) during the Holocene, by combining results of different dating techniques

Sparta fault is an impressive landform, located on the eastern front of Taygetos mountain, southern Greece. Detailed morphotectonic observations on this fault suggest that it should be active at least since Early Quaternary. However, according to the current seismological knowledge, this region is characterized by very low seismicity. The only reported earthquake to have occurred in this area is that of 464 b.c., a destructive event that devastated the whole city of Sparta. In order to get information on the occurrence of past earthquakes during the Holocene, results of different independent dating works that have performed along the Sparta fault were used. These researchers confirm the existence not only of the 464 b.c. earthquake but also of several more that occurred at ca. 3900 b.c., 2500 b.c. and 2000 b.c., 550 a.d. and 1000 a.d. The events that occurred at 2500 and 464 b.c. should correspond to major events of magnitude of the order of 7, which ruptured the entire length of the fault, while these at 3900 b.c., 2000 b.c., 550 a.d. and 1000 a.d., to smaller events of magnitude 6-6.5. The return periods of strong earthquakes along the Sparta fault is estimated to be around 2000 years, but within these periods events of smaller magnitude that ruptured segments of the fault have also occurred.