Earthquakes

Abstract

Earthquakes have played a major role in the evolution of the Mediterranean landscape. They are the most important geohazard in the region and huge sums are invested annually in seismic monitoring, hazard zoning, and earthquake prediction, and in the design of earthquake-resistant buildings and infrastructure. Large earthquakes of magnitude >7.0 have been recorded across the region and the archaeological record shows that earthquakes have posed a major hazard to human settlements for thousands of years (Ambraseys 1971; Shaw et al. 2008; Bottari et al. 2009; Figure 16.1 and Table 16.1). The study of Mediterranean seismicity started about 2,400 years ago when the first earthquake catalogue was compiled in ancient Greece (Papazachos and Papazachou 1997; Guidoboni et al. 1994). This key development predated, by several centuries, the construction of the first seismograph in China (Bullen and Bolt 1985). Since these early developments a great deal of research has been carried out to improve our understanding of earthquakes and associated hazards in the Mediterranean region and to provide protection from them. Earthquake resistant buildings—such as houses with timber bracing—were introduced in Asia Minor in the seventeenth century (Kirikov 1992; Simopoulos 1984; Stiros 1995) and the first strict anti-seismic construction regulations were implemented on the island of Levkas, Greece, in the nineteenth century under British Rule (Stiros 1995). The first ‘modern’, regional-scale earthquake maps and catalogues were compiled as early as the middle of the nineteenth century (Mallet 1858). Despite this progress, the death toll from Mediterranean earthquakes is still high and earthquakes in the region continue to surprise geoscientists. For example, the diffuse pattern of seismicity that is especially characteristic characteristic of the eastern Mediterranean (Figure 16.2) is not easily reconciled with existing plate tectonic models, and many faults that are believed to demarcate plate boundaries (such as the Jordan Rift) are currently quiescent (Figure 16.3). Similarly, the 1995 Grevena-Kozani earthquake was a surprise for scientists, for it hit the heart of what was believed to be an aseismic region in northern Greece (Stiros 1998a). Furthermore, key aspects of the geodynamic background of the Mediterranean region remain a matter of debate.