Filenews 28 October 2021 - by Vassos Vassiliou
Two earthquakes with magnitudes of 3.3 and 3.1 degrees on the Richter scale yesterday upset residents mainly in Limassol, although they were also felt in other areas of Cyprus. Residents of various areas described online how they experienced the earthquakes.
Both seismic tremors were centred in Gerasa northwest of Limassol, where the active fault of Gerasa is located, which, as recalled by the Senior Geological Officer of the Geological Survey Department Dr. Sylvana Pilidou, in 1999 had caused the strong earthquake of 5.6 Richter.
He also recalled that in the last 20 years, this particular earthquake was followed by 1,000 earthquakes of which 20 were of magnitude beyond 4 degrees while about 250 were of magnitude greater than 3 degrees. Of these, about 200 were felt.
It is noted that the Gerasa fault is the largest in Cyprus and has a length of 25 km. The fault breaks down into two sections 10 and 15 km long respectively. It is considered the only active rift in Cyprus.
However, according to estimates, it cannot cause an earthquake beyond 5.6 on the Richter scale, although an earthquake of this magnitude will shake the whole of Cyprus. A fault is considered active when an earthquake has been created in it in the last 10,000 years.
The remaining faults (Ovgou in Nicosia, Kythrea and two others in Paphos) are considered too small to cause strong earthquakes, although theoretically they are active.
In Cyprus the largest fault was the Arakapas fault which, however, is inactive. It is also called a transformation rift, because it was created 80 million years ago, when Cyprus was still under the sea and in the process became inactive.
About 60 million- 70 million years ago, when Pentadaktylos and Troodos began to emerge from the sea, gradually began the erosion of materials that constituted the two mountains, resulting in these materials to fill the basin of Mesaoria.
According to estimates, because the corrosion was relatively fast, the materials deposited did not manage to be compressed on their own and under their weight, which resulted in subsidence through the centuries. This process leads to the creation of cracks that contribute to the filling of the gaps created.
The materials that came from the corrosion of Pentadaktylos reach up to Mia Milia while the rest of the materials whose erosion created the soil of Nicosia, come from Troodos.
The boundary of pentadaktylos materials extends to Kioneli while the boundary of the Troodos materials reaches up to Agios Dometios.
Many materials were transported by rivers. The rivers Serrahis and Pedieos continue to this day to carry various materials.
