Frequency of large past earthquakes in the Aegean and associated risk susceptibility. Combining cosmogenic dating, historical data, and spatial analysis (FEARS)
Project leader: Lucilla Benedetti (CEREGE)
Participants: Samuel Robert (ESPACES), Olivier Bellier (CEREGE), Jules Fleury (CEREGE), Matthieu Ghilardi (CEREGE), Magali Rizza (CEREGE), Jim Tesson (CEREGE), Cengiz Yildirim (ITU), Vasiliki Mouslopoulou (GFZ Postdam), Ersen Aksoy (Mugla Univ.).
The objective of this project is to explore the concept of “susceptibility to seismic hazard” in specific areas of the Mediterranean that are 1- associated with an important seismic hazard and 2- important for the economical income of their countries in term of tourism either because of their location close to sea shore, or because of their cultural heritage.
The Aegean region appears to be an appropriate place to investigate those aspects at a regional scale. It is one of the seismically most active region in the Mediterranean, but the seismic risk is, however, not very well characterized, the sources of strong earthquakes being mostly unknown. Human and economical stakes associated with a strong earthquake that would occur today in this region are not well characterized either. The Aegean, which includes the major part of Greece and western Turkey, is however one of the most touristy area in the Mediterranean.
Thus to investigate human-environment interactions through the study of seismic hazard and its consequences on society in the Aegean, we will aim in the framework of this project at:
1- acquiring a long record of paleoearthquakes in specific targeted areas to assess specific metrics associated with the past earthquakes triggering and future repetition,
2- collecting qualitative and quantitative information on the humans -stakes in the same area with a spatial dimension
3- providing metrics of seismic risk exposure allowing to define how future earthquakes may affect the socio-economic development of these regions using entries from the part 1 and 2.
This methodology will be developped in 2 targeted areas in Greece and Turkey to confront and test this approach in different environments. We will first map the main active faults using high resolution satellite images. Such images will also be used to construct a digital elevation model of each studied areas. The study of reports on destructions related to catastrophic earthquakes that have occurred in the area will allow the making of the isoseismal contours centred on the approximate location of the earthquake epicentre. To assess the human stakes associated with seismic risk in the studied areas, various sources of information will be used (land use data, spatial structures of each area, topography, existence of archaeological sites of great importance, demographic data, infrastructures, housing and administrative units). The new paleoseismological methodology successfully developed on normal faults in Italy using 36Cl cosmogenic dating, will allow to acquire a long record on past earthquakes of targeted normal faults in the studied areas and understand how the earthquakes have repeated over the last 10-20 kyrs. All those information and data gathered and acquired during the project will be integrated into a geographical database to caracterise the territories. According to a scale which is to be designed, these zones will be classified as being highly susceptible (because past seismicity is high and present human stakes are numerous and of major importance) or, at the opposite, lowly susceptible (no past seismicity + no human stakes).