A comparison of 10³–10⁵ year uplift rates on the South Alkyonides Fault, central Greece: Holocene climate stability and the formation of coastal notches

Measurements of Holocene coastal notch sequences exposed in the footwall of the active South Alkyonides normal fault, Greece, reveal 3 Holocene paleoshorelines near the lateral fault tip, rising in elevation eastward toward the center of the fault, where a 4th paleoshoreline appears. The implied eastward increase in Holocene uplift rate mirrors that for an uplifted Quaternary marine terrace (0.29 mm/yr – 0.55 mm/yr from west to east). Assuming these uplift rates were constant through the Holocene, notch elevations predict ages of 650, 1900, 3700 and 6500 years B.P., comparable with published ¹⁴C ages on notch fauna, and well correlated with periods of relatively stable Holocene climate. We propose that the notch sequences formed when post-glacial sea level rise became outpaced by the coastal uplift rate, whilst individual notches formed when stable climate facilitated sustained erosion. The parity of the Holocene and Quaternary uplift rates suggests that notch sequences could be used to characterize long-term patterns of uplift, slip-rate and seismic hazards on active normal faults, if 6500 years is long enough to fully characterize temporal variation in the seismic cycle.