Palaeoseismology and tectonic geomorphology for detecting the seismic behaviour of the Pidima-Anthia Fault, south Greece

Abstract

Geomorphologic analysis and data from paleoseismological sites across segmented active faults help the evaluation of past and future seismic faulting. The study of paleo-earthquakes on the Pidima-Anthia Fault provides an opportunity to unravel the seismic behaviour of the Eastern Messinia Fault Zone (EMFZ) that defines the western border of the N-S trending Taygetos Mtn range in Peloponnese (southern Greece). This fault zone is segmented and includes a complex system of primarily normal fault- segments dipping westwards, with a traceable length from 6-10 km. We applied geomorphological and palaeoseismological analysis across the Pidima-Anthia Fault segment. The palaeoseismological trench data provide evidence for five M >6.4 earthquakes and indicate an apparent slip rate of 0.23 mm/a. Geomorphologically, the modelling of a footwall series of triangular facets, attest to a slip-rate estimation in the order of 0.28-0.44 mm/a. These data highlight that the slip rate of the fault is remarkably stable for the Quaternary period but particularly over the last 17 ka period, as well as that this duration is enough for a morphogenic active fault to create seismic landscapes. The Holocene earthquake history of the Pidima-Anthia Fault allows its comparison with six other known active normal faults of southern Greece. The overall data indicate a pattern of earthquake clustering in the southern Greece faults ("Wallace-type" behaviour). In particular, the Pidima-Anthia Fault's seismic history resembles with time predictable earthquakes and clustering during the Holocene. However, the Pidima-Anthia Fault during the current period (i.e., post 1 Ka AD) does not display cluster time-predictable behaviour, and a strong earthquake can happen at any time.