Raised Holocene paleo-shorelines along the Capo Vaticano coast (western Calabria, Italy): Evidence of co-seismic and steady-state deformation

摘要

Detailed mapping of geomorphological and biological sea-level markers around the Capo Vaticano promontory (western Calabria, Italy), has documented the occurrence of four Holocene paleo-shorelines raised at different altitudes. The uppermost shoreline (PS1) is represented by a deeply eroded fossilifer-ous beach deposit, reaching an elevation of ～2.2 m above the present sea-level, and by a notch whose roof is at ～2.3 m. The subjacent shoreline PS2 is found at an elevation of ～1.8 m and is represented by a Dendropoma rim, a barnacle band and by a wave-cut platform. Shoreline PS3 includes remnants of vermetid concretions, a barnacle band, a notch and a marine deposit, and reaches an elevation of ～1.4 m. The lowermost paleo-shoreline (PS4) includes a wave-cut platform and a notch and reaches an elevation of ～0.8 m. Radiocarbon dating of material from individual paleo-shorelines points to an average uplift rate of 1.2-1.4 mm/yr in the last ～6 ka at Capo Vaticano. Our data suggest that Holocene uplift was asymmetric, with a greater magnitude in the south-west sector of the promontory, in a manner similar to the long-term deformation attested by Pleistocene terraces. The larger uplift in the south-western sector is possibly related to the additional contribution, onto a large-wavelength regional signal, of co-seismic deformation events, which are not registered to the north-east. We have recognized four co-seismic uplift events at 5.7-5.4 ka, 3.9-3.5 ka, ～1.9 ka and ＜1.8 ka ago, superposed on a regional uplift that in the area, is occurring at a rate of ～1 mm/yr. Our findings places new constrains on the recent activity of border faults south of the peninsula and on the location of the seismogenic source the 1905 destructive earthquake.