THE SEISMICITY OF CYPRUS

Cyprus lies within the Alpine-Himalayan seismic zone, in which about 15% of the world earthquakes occur. The seismicity of Cyprus is thought to be due to the “Cyprus Arc (Figure S1)”, which constitutes the tectonic boundary between the African and Eurasian lithospheric plates (Figure S2) in the region. It is situated in the sea to the west and south of Cyprus. Many epicentres are concentrated along this arc (Figures S3, S4), indicating that the tectonic movements along it are the cause of many earthquakes.

Historical references and archaeological findings reveal that strong earthquakes struck Cyprus in the past, which on several occasions destroyed its towns (Photo S1). Historical data show that 16 destructive earthquakes with intensities of at least VIII on the modified Mercalli scale occurred between 26 BC and 1900 AD. Pafos was levelled in 15 BC while in 76 AD the town was destroyed along with Salamis and Kition. Salamis and Pafos were destroyed again in 332 AD and 342 AD.

More accurate data regarding the earthquakes occurring in the Cyprus region have been collected since 1896, when seismological stations started operating in neighbouring countries. The situation has improved considerably since the mid-1980s, with the establishment of seismological stations in the southern and northern parts of the island.

In the time period 1896-2004, more than 400 earthquakes with their epicentres on Cyprus and the surrounding region were felt in parts of the island. Of these, 14 caused damage and some of them had victims (Figure S6). The most catastrophic ones were those of 1941, 1953, 1995 (Photos S5, S6), 1996 and 1999.

The study of the historical and recent earthquakes shows that the distribution in time of the seismic activity is not regular, but there are periods of intense activity followed by periods of quiescence. In the years 1995-1999 there was an increase in seismic activity with strong to very strong earthquakes with magnitudes of 5.6-6.5 on the Richter scale.

Cyprus lies in a seismic zone and the whole of the island can be considered as an earthquake vulnerable area. However, the most earthquake prone area of Cyprus (Figure S7) is the coastal zone that extends from Pafos through Limassol and Larnaca to Famagusta.

Earthquakes are natural phenomena, which Man cannot avoid. However, Man is in a position to reduce considerably or even obliterate the effects of earthquakes on structures and generally on the environment and in this way offer protection to himself. In order to achieve this, measures have been taken in Cyprus since the 1980s that have concentrated principally on the following: a) the study and better understanding of the seismicity of the Cyprus region (Figure S8); b) the study of the behaviour of the soils during an earthquake (Figure S9) in which buildings and other structures are founded, with special emphasis on the soils of urban and coastal areas; c) the construction of seismic resistant structures and the anti-seismic shielding of existing ones; and d) the establishment of the necessary infrastructure for immediate and effective reaction following an earthquake.

Modern seismological stations (Figure S10, Photos S4, S3) are in operation today in the northern and southern parts of Cyprus. The basic targets of the operation of these stations are: a) the collection of trustworthy data for the study of the seismicity of Cyprus; b) the immediate and accurate analysis of the earthquakes occurring in the Cyprus region and communication of the results to international and regional seismological centres; and c) immediate informing to the relevant authorities and the public for all felt earthquakes