The United States Geological Survey detected a Magnitude 5.5 Earthquake at a depth of 10 km close to the northern shore of the Gulf of Corinth, slightly after 5.35 am local time (slightly after 3.35 am GMT) on Wednesday 17 February 2021. There are no reports of any damage or casualties associated with this event, but people have reported feeling it locally.
The
location of the 17 February 2021 Gulf of Corinth Earthquake. USGS.
The geology beneath the Gulf of Corinth is slightly complicated. The
Gulf forms part of the boundary between the Aegean and Eurasian Plates.
This is a divergent margin, with the two plates moving apart, causing
sinking in the centre of the Gulf, with the rocks on either side sinking
along a series of faults, a structure known as a graben to geologists.
The graben beneath the Gulf of Corinth. The drawing apart of the
Aegean and Eurasian Plates causes the lithosphere under the Gulf to
thin, and the rocks of the crust to sink, splitting along a series of
concentric faults on either side of the Gulf. Moretti et al. (2003).
However this is not the whole story, as to the south of the Peloponnese
the African Plate is being subducted beneath the Aegean Plate along the
Hellenic Subduction Zone, passing under The Peloponnese and the Gulf of
Corinth (note this is oceanic plate attached to the north of Africa, not
the continental African Plate).
Thus there are two potential causes of Earthquakes beneath the Gulf of
Corinth; shallow faulting associated with the graben caused by the
drawing apart of the Aegean and Eurasian Plates, and a deeper zone where
friction between the subducting African Plate and the overlying Aegean
and Eurasian Plates can lead to quakes. However, depth is not the only
guide to the cause of a quake, as the friction of the African Plate
passing under the Aegean and Eurasian Plates also exerts stresses on the
rocks in the graben, and can contribute to quakes there.
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