Surveying of neotectonic structures and macro-seismic effects on the volcanic rocks of Western Lesvos. A case study: The earthquake in Skalochori, Lesvos (4.0 Mw) of 15 April 2021

The island of Lesvos is located in the North Aegean, a region with high seismicity, directly affected by the southern branch of the North Anatolia Fault (NAF) which is an active right-lateral strike-slip fault.

The purpose of this study is the localization, recording and cartographic mapping of neotectonic structures and macro-seismic effects on the volcanic rocks of Western Lesvos, after the occurrence of an earthquake in ​​Skalochori. The earthquake was shallow - focal depth 6km -, with its epicenter in the inland, 44km NNW of Mytilene and the geological background of the area consists of volcanic rocks and quaternary deposits.

In this paper we collect seismological data from research institutes in the area, we collect and analyse data from the field and we review of published research and data on the active trend field in the North Aegean region.

The fieldwork identified a variety of evidence in a major NNW-SSA address band,10km long and 7km wide. They mainly concern surface ruptures, movements/falls of rocks and small landslides. Their main characteristics are the small size (cracks of millimeters to a few centimeters, volume drops of a few m³), which show a specific and systematic appearance and distribution in space. A left-lateral strike-slip fault was also detected.

The correlation of the main direction of the ruptures, the arrangement of the epicenters, the seismic moment tensor solution and the fault, in combination with the existing research leads to the conclusion that the evidence collected is related to the recent seismic activity and is identical with the existing active field.