Active faulting at the Corinth Canal based on surface observations, borehole data and paleoenvironmental interpretations. Passive rupture during the 1981 earthquake sequence?

摘要

The most important active fault that crosses the Corinth Canal is studied in detail, involving surface observations, borehole data and paleoenvironmental interpretations. This fault intersects and/or is parallel and at short distances from major infrastructure facilities such as the Athens-Corinth highway, the railway and the Corinth Canal. It is a secondary structure accommodating displacement between the other major E-W trending active faults. It exerts an influence on the topography and the stratigraphy, backtilting Middle Pleistocene sediments on its immediate footwall, showing also significant synsedimentary activity. It has a short length (similar to 5.5 km) and is not expected to produce extensive primary surface ruptures and large displacements (<14 cm). Borehole data and correlation between the footwall and hangingwall horizons, indicate that only minor displacement of several meters has been accumulated over the last 175 ka, implying a low slip-rate (similar to 0.04 +/- 0.02 mm/year). Paleoenvironmental interpretations based on borehole data show a very complex sedimentation history during the Middle and Upper Pleistocene that involves subaerial exposure, coastal, lagoonal, shallow marine environments and possibly even some lake sediments. There is strong evidence that this fault was passively ruptured up to 6 cm during the 1981 earthquake sequence and questions emerge on whether part of its throw can be attributed to such a mechanism. (C) 2014 Elsevier B.V. All rights reserved.