Assessment of the earthquake potential of the west Aegean region of Turkey based on seismicity, tectonics, crustal deformation and geo-archaeological evidence and its geotechnical aspects

The western Aegean region of Turkey is highly populated; the centrally-located city of Izmir is the third largest city in Turkey. This region has suffered very large earthquakes in the past, of which one of the most devastating occurred in 1928. Some areas are particularly prone to severe ground liquefaction. This study is concerned with the earthquake potential of the region, focusing on a possible earthquake faulting mechanism and its associated characteristics based on historical and current regional seismicity, tectonics, crustal deformation and geo-archaeological evidence. The first part of the study presents a faulting mechanism, tectonics, recurrences and the fundamental characteristics of existing faults and past earthquakes. Then, the characteristics of potential earthquakes are discussed in light of evaluations of recent crustal deformation and empirical relations developed for Turkey by the first author. The final part presents geotechnical aspects, including liquefaction and the characteristics of strong ground motions recorded in the region, such as spectral acceleration, attenuation of maximum ground acceleration and velocity. Furthermore, their possible implications are discussed in view of current Turkish seismic design codes. The faulting mechanism of regional earthquakes has indicated that the classical horst-graben concept does not explain the earthquake mechanism in the region of concern. The magnitude of earthquakes inferred from the length and type of known active faults may be up to 7.7. Based on an evaluation of crustal deformation in the region, the highest disturbing stress and mean stress concentration with a compressive character occurs in close proximity to İzmir. The spectral accelerations generally exceed those of Turkish seismic design codes. The liquefaction potential in areas of alluvial quaternary deposits is particularly high and is one of the major geotechnical issues in light of historical records and evaluations presented in this manuscript.