The Lapithas Mountain faults and nearby archaeological damage, western Peloponnese, Greece
Mason, Jack; Reicherter, Klaus; Papanikolaou, Ioannis
published: Dec 1, 2015
Fault slip data are analysed from the E-W striking northern and southern Lapithas Mountain faults, which respectively form the northern and southern boundary between the Alpine mountain horst and the Quaternary basins. Kinematic indicators such as corrugations and striations show that slip directions vary on both these individual faults, which is typical for the Aegean region. Slip direc- tions converge towards the centre of the fault where there is pure dip-slip movement; towards the lateral tips the slip is more oblique with a strike-slip component. These fault slip orientations and calculations of along strike variations in observable throw, are used in combination with published earthquake and offshore bathymetry data to accurately determine the lengths of both the northern and southern Lapithas faults. The northern Lapithas fault comprises two segments; a ca. 18 km long onshore segment and a ca. 15 km long offshore segment. Based on empirical calculations and when viewed separately, potential maximum earthquake magnitudes (Mw) of 6.5 and 6.4 could occur on the onshore and offshore segments respectively. As a worst case scenario, these two segments could both rupture during an earthquake. A multi-segment rupture totalling 33 km in length is capable of producing a maximum magnitude (Mw) of 6.9. The total length of the southern Lapithas fault is ca. 5 km and could therefore produce a maximum potential magnitude (Mw) of 5.8. There are archaeological sites in the vicinity of the Lapithas Mountain which show evidence of possible earthquake damage. Samicum, which is located on the western end of the Lapithas Mountain, contains collapsed towers and displaced walls and blocks; so far this damage has not been attributed to earthquakes, but because of the site's location, the Lapithas Mountain faults are a likely source. Ancient Olympia, which is located 10 km to the north, has oriented fallen columns which have been attributed to earthquakes in AD 522 and/or AD 551. However, a review of the literature and earthquake records shows that no earthquakes in these years can explain the damage; further work is need to determine whether the damage was caused by earthquakes and, if so, to find the causative fault and accurately date the damage.