Earthquakes
Tsunamis
Conclusion
Further Reading
Of course, it is well known that Cyprus is prone to earthquakes. Rarely a
day goes by without a minor tremor, mostly imperceptible. Major ones are,
fortunately, rare but, in the past, there have been some very severe ones
which have devastated large areas and caused many deaths. There is plenty of
evidence of this.
In 1956, I remember snorkelling at Salamis and marvelled at the harbour
quays a couple of metres under the surface. The rows of amphorae, ready for
loading on boats, were clearly visible, as were numerous other artefacts
dating from 1600 years earlier. The level of the land dropped an estimated 4
metres in a single earthquake which must have had an intensity of at least 8
on the Richter scale, probably more. At Kourion, there is evidence that the
city was probably down to sea level and one person has claimed it was
initially destroyed by a tsunami and then rose to its present level by
seismic elevation, some ten years later.
In recent times, one earthquake in September 1953 in the Paphos region
caused considerable destruction and killed 63 persons. Since then, there
have been few severe ones with relatively little destruction and few
fatalities.
Santamas (1988) reports that since 1900, Cyprus has been affected by
approximately 800 earthquakes of magnitudes ranging from 4.0 - 7.0 on the
Richter scale, 21 of which had magnitude ≥ 5. He concluded that there is a
possibility of a potentially damaging earthquake will occur approximately
every 12 years and a destructive earthquake every 25 years.
The earthquakes are caused by the African continent moving northwards and
the tectonic plate colliding with the Eurasian and Anatolian plates. There
appear to be three parallel fault lines. The most important one is the
Anatolian fault running from Greece, through Istanbul and parallel with the
North Coast of Turkey. South of this, there is a potential fault line
running along the north side of the Troodos massif. This may have been
responsible for the historic destruction of Nicosia and Salamis in the 4th c
AD. The one most likely to affect the island is the Cyprian arc. This runs
roughly parallel to the South Coast of Cyprus, about 100 - 200 km offshore,
with subduction under the island. It is an active fault and shock waves from
it are the cause of most of the temblors that are felt in the Paphos,
Limassol and Larnaca districts.
Since 26 December 2004, the world has become sensitised to the risk of
tsunamis and Cyprus is no exception. Tsunamis are caused when there is a
major drop in the level of the seabed. In the case of the catastrophic Asian
one, the drop has been estimated at 30 metres, in conjunction with an
earthquake of 9.0 on the Richter scale.
Tsunamis are known in the Mediterranean, especially in the Aegean Sea. It
is not impossible for one from there to reach the Akamas coast, but it is
not likely. Perhaps more likely would be a sudden subduction of the African
plate, causing one to reach the South Coast. However, the chances of this
happening are remote, even if it may have happened in the past. Even if it
did, the energy involved would be small compared with the Asian event and
large-scale destruction from the wave itself would seem remote.
It is worth noting that if the Cyprian Arc did suddenly subduct in such a
way as to cause a tsunami, an early warning system would be useless. From
the time of the quake causing it to the time of it hitting the shoreline
would be about 5 to 15 minutes. It is clearly impossible for the event to be
interpreted, the public to be warned and to react in this short period.
The risk of earthquakes in Cyprus is omnipresent. Most houses are
constructed accordingly. The risk of a catastrophic tsunami is remote.
SPATIAL CONSIDERATIONS IN THE REANALYSIS OF CYPRUS EARTHQUAKE
EARTHQUAKE RISK ASSESSMENT CASE STUDY: CYPRUS
Reflections after Fukushima, 11.03.2011
The earthquake and subsequent tsunami that hit the north-east coast of
Japan on 11 March 2011 merits a little reflection as to whether a
similar set of circumstances could hit Cyprus. Since the above text was
written, a major technical paper has been published, "Seismotectonics of
the Cyprian Arc", Shimon Wdowinski et al. The strongest earthquakes
along the Cyprian arc in recent times have been the 1996 Paphos quake
and the 1998 Adana one, respectively of magnitude 6.8 and 6.2. These
were apparently deep (up to 85 km) and were strike-slip events and not
subduction. This type of earthquake would never produce a tsunami.
Notwithstanding, subduction does occur in the eastern part of the arc.
However, the relative movement of the plates is small and the
accumulated energy is not great. It would therefore make it unlikely
that a major fall would occur, causing a tsunami. It should also be
considered that the Mediterranean is relatively shallow and small; if a
tsunami did occur, it is not likely to be very high or long-lasting.
That having been said, it is believed that Cyprus has been hit by
tsunamis in the past.
Without doubt, most of the damage experienced in Japan and particularly
in the Fukushima nuclear complex was caused by the tsunami and not by
the earthquake. If a large earthquake occurred in the Cyprian arc, the
opposite would be the case in Cyprus; most of the damage would be from
the earthquake and little from the tsunami, if such happened.