Correlating the Damage Pattern and the Geological Structure. Local Site Effects From the 2006 MW=6.7 Kythira Island Intermediate Depth event, SW Greece.

Abstract eng:
Tens of examples of shallow earthquakes have shown that areas of severe damage are highly localised and that the degree of damage can change abruptly over short distances due to changes in local geology. In this paper we show that the geological structure such as the surface geology, the topography and the distance from detachments and neotectonic faults are controlling factors of the ground motion also for the intermediate depth events. Our case-study refers to the 8th of January 2006 Mw=6.7 thrust faulting event that occurred on the Hellenic subduction zone eastwards the island of Kythira at 70 km depth. Damages and other remarkable earthquake environmental effects (rockfalls, landslides, fractures) were recorded mainly in the village of Mitata. Even though several villages of the island are equidistant from the epicentre, only the Mitata village was damaged. In particular, in the Potamos village situated only 35 km from the epicentre the reported MM intensity was V+, whereas in the Mitata village, situated 40 km away from epicenter, having a similar quality of buildings, the recorded intensity was VII+. A series of geological cross-sections have been constructed, which demonstrate that the variation of the damage pattern was due to the highly unfavorable site specific conditions of the Mitata village. The village of Mitata was devastated (Intensity XI) by a similar deep sourced, but significantly stronger event (M=7.9) in 1903, exhibiting once again significantly higher damages than the neighboring villages, confirming its unfavourable geological site condition.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket