Seismological, structural and geotechnical aspects of the 2020 Samos (Aegean Sea) earthquake

Overview

The 30 October 2020 M7.0 Samos (Kuşadasi Gulf, Izmir) earthquake reportedly caused two fatalities and 19 minor injuries at Samos Island, while in Western Turkey, the effects of the event were more severe, with 115 fatalities, over 1,030 injuries and structural damage that included at least six collapses in Izmir, approximately 70 km away from the epicentre. This webinar will give an overview of this notable event based on recent analysis of seismological data, as well as field reconnaissance observations.

The earthquake ruptured a north dipping normal fault, projecting offshore, very close to the northern coast of Samos Island, which was previously inferred from the bathymetry and regional tectonics. Following the main event, a cascade of M6+ earthquakes that occurred in the Aegean Sea, highlighting the significant earthquake risk imposed on urban areas from unknown and unmapped offshore faults. The typology of buildings affected in the Samos region were mostly of plain masonry with few occurrences of reinforced concrete structures.

Typical damage patterns, as identified in the surveyed buildings, will be discussed and qualitatively interpreted in the context of their typology, dimensions and the quality of their construction. The earthquake also led to some landslides, evidence of liquefaction, lateral spreading and damage to quay walls in ports on the northern side of Samos Island. Despite the proximity to the fault, and the significant amplitude / duration of shaking, the associated liquefaction phenomena were not pervasive, while no liquefaction was observed in and around Izmir. Both Samos and Izmir Bay yielded interesting observations regarding site and topography effects.