Localization of Quaternary slip rates in an active rift in 10⁵ years: An example from central Greece constrained by ²³⁴U‐²³⁰Th coral dates from uplifted paleoshorelines

Abstract

[1] Mapping, dating, and modeling of paleoshorelines uplifted in the footwall of the 1981 Gulf of Corinth earthquake fault, Greece (Ms 6.9-6.7), are used to assess its slip rate history relative to other normal faults in the area and study strain localization. The 234 U-230 Th coral ages from Cladocora caespitosa date uplifted shoreface sediments, and paleoshorelines from glacioeustatic sea level highstands at 76, (possibly) 100, 125, 175, 200, 216, 240, and 340 ka. Uplifted Quaternary and Holocene paleoshorelines decrease in elevation toward the western tip of the fault, exhibiting larger tilt angles with age, showing that uplift is due to progressive fault slip. Since 125 ka, uplift rates varied from 0.25 to 0.52 mm/yr over a distance of 5 km away from the fault tip. Tilting was also occurring prior to 125 ka, but uplift rates were lower because the 125 ka paleoshoreline is at 77% of the elevation of the 240 ka paleoshoreline despite being nearly half its age. Comparison of paleoshoreline elevations and sedimentology with the Quaternary sea level curve shows that slip rates increased by a factor of 3.2 ± 0.2 at 175 ± 75 ka, synchronous with cessation of activity on a neighboring normal fault at 382-112 ka. We suggest that the rapid localization of up to 10-15 mm/yr of extension into the narrow gulf ($30 km wide) resulted from synchronous fault activity on neighboring faults followed by localization rather than sequential faulting, with consequences for the mechanism controlling localization of extension.

Deformation pattern of the 6 and 7 April 2009, <i>M</i><sub>W</sub>=6.3 and <i>M</i><sub>W</sub>=5.6 earthquakes in L'Aquila (Central Italy) revealed by ground and space based observations

“…Overall, the value of this ratio is very important particularly for seismic hazard assessment purposes since it governs the fault slip-rates. For example, in some regions such as the Gulf of Corinth and the region of Calabria in Italy the only way to deduce slip-rates covering a long-time period, is from dated uplifted Quaternary marine terraces situated on the footwall of the faults (Bordone and Valensise, 1998;Houghton et al, 2003;Tortrici et al, 2003;Catalano et al, 2003;McNeill and Collier, 2004;De Martini et al, 2004;Ferranti et al, 2007;Roberts et al, 2009). Due to subsidence the entire hangingwall area is usually located offshore.…”

Quantitative dating of Pleistocene deposits of the Kyrenia Range, northern Cyprus: implications for timing, rates of uplift and driving mechanisms

“…The interaction of such deep-seated tectonic processes drives surface uplift in various parts of the easternmost Mediterranean and the adjacent region. For example, major surface uplift occurred during the Plio-Pleistocene in the Peloponnese and elsewhere in Greece (Roberts et al 2009;Turner et al 2010) and in the Taurus Mountains of southern Turkey .…”

Fault architecture and deformation processes within poorly lithified rift sediments, Central Greece

“…Collier, 1990;Dia et al,1997;Roberts et al, 2009;Turner et al, 2010). The marls are either cohesive fine-grained (silt-clay) carbonates or less cohesive silty carbonates interbedded with sands.…”