Reicherter et al. 2006a

Reicherter, K., Hübscher, C., Becker-Heidmann, P. (2006): First evidence for an earthquake-induced tsunami and tsunamites in the western Mediterranean: the 1522 Almería earthquake. – In: Geologische Vereinigung (Hg.): Abstracts GV Conference Potsdam 2006, S. 60, Mendig

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Abstract:

The 1522 Almería earthquake (M > 6.5) affected large areas in the western Mediterranean and caused about 2000 causalities. Different epicentral areas have been suspected, mainly along the 50 km long sinistral Carboneras Fault Zone (CFZ), however no on-shore surface ruptures and paleoseismological evidences for this event have been found. High-resolution sea floor imaging (narrow beam sediment profiler) yields evidence for an offshore rupture along a strand of the CFZ that is supported by evaluation of historic documents. We present a isoseismal map of the 1522 Almería earthquake. Based on these data, a new epicentral area precisely at the observed sea floor rupture area is proposed at N 36° 42, W 2° 23 in the Gulf of Almería. Drilling in lagunas and salinas of the near-by Cabo de Gata area proved sedimentary evidence for paleo-tsunamis along the Spanish Mediterranean coast. Several coarse grained intervals with fining-up and thinning-up sequences contain rip-off clasts, shells of lamellibranchs and foraminifera. The coarse-grained intervals have erosive bases and show up to three sequences divided from the next one by a small clayey layer. These intervals are interpreted as tsunamites, and the sequence as “tsunami trail”-deposits. We have also found multiple intercalations of those coarse grained layers downhole, which is interpreted as either an expression of repeated earthquake activity or tsunami-like waves induced by submarine slides triggered seismic shaking in the Gulf of Almería. The clayey sediments below the tsunamite layers have been dated with 14C-AMS as 680±30 BP for the upper layer (0.49 m below surface) and 850±35 BP for the lower layer (1.28 m below surface). The upper layer may well correlate with the 1522 Almería earthquake, the second may possibly be related to a poor description of an east Andalusian earthquake in 1013/1014. The coast of southern Spain, the Costa de Sol, the touristic hot spots in the is one of Mediterranean Europe and very densely populated. Hence, the impact on the vulnerability is of great concern for society and economy, considering destructive earthquakes in coastal residential and industrial areas, especially a holiday and recreation area in the western Mediterranean region. Our evidence suggests a certain tsunami potential and hazard for offshore active and seismogenic faults in the western Mediterranean region.

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