Lateral propagation of the surface trace of the South Alkyonides normal fault segment, central Greece: its impact on models of fault growth and displacement–length relationships

The evolution of deformed marine terraces and drainage systems have been examined in order to investigate the growth and lateral propagation of an active normal fault. Geological mapping has revealed three distinct raised marine terraces in the immediate footwall of the western end of the active South Alkyonides Fault Segment (SAFS), Gulf of Corinth, central Greece. We correlate these terraces with sea-level highstands at 125, 240 and 330 ka. Using elevation estimates of the inner edges of the terraces we show that uplift rates decrease towards the Perachora Fault Segment Boundary at the western end of the SAFS. Analysis of terraces and drainage wind gaps in the footwall of the fault shows that the surface trace of the SAFS propagated westwards at a rate of 12.1–16.7 mm/y over at least the last 330 ka. Whilst the surface trace length has increased, analysis of the geometry and kinematics of fault-slip suggests that fault length at depth has remained fixed, implying progressive increase in the values for the displacement–length ratio. If this is correct, growth is not self-similar and fault length has been established early in the evolution of the system, i.e. before 330 ka.