Recent history of the Eastern Eliki Fault, Gulf of Corinth: geomorphology, palaeoseismology and impact on palaeoenvironments

ABSTRACT

The Eliki fault system dominates the landscape of the southwestern shore of the Gulf of Corinth, where rapid extension rates result in frequent earthquakes. These include an event in 373 BC that destroyed the city of Helike and a recent event in 1861. Uplifted Late Pleistocene marine terraces within the Eastern Eliki Fault footwall suggest revised slip rates of ∼3–5 mm yr⁻¹, contributing ∼2–3 mm yr⁻¹ geological extension to a net geodetic extension of ∼10–15 mm yr⁻¹ across this part of the rift. Palaeoseismological trenches indicate two and possibly three earthquakes on the Eastern Eliki Fault in the last 1500 yr, including the 1861 earthquake. One trench (EET1A) reveals displaced stratigraphy, but the main fault trace is thought to lie further south beneath the Old National Road. Trench EET1A reveals liquefied sediments associated with an event between AD 1460 and the present, which may be the 1861 event, and displacement during a second event in the interval AD 440–1410 or AD 1270–1640. A third earlier event identified by liquefaction occurred on the Eliki or a nearby fault in AD 440–1410. Using the 1861 and second event (most likely AD 1270–1640), the interval between recent earthquakes is ∼200–600 yr. Suitable trench sites are rare in this region, compounded by human activity over several thousand years. Borehole and trench data indicate that the Kerynites river frequently flowed eastwards along the Eastern Eliki Fault during the last 20–40 kyr, possibly influenced by tectonic tilting from the Eliki and Aigion fault systems and natural channel avulsion.