Reconnaissance of 2020 M 7.0 Samos Island (Aegean Sea) earthquake

Abstract

The Samos Island (Aegean Sea) Earthquake occurred on 30 October 2020. It produced a tsunami that impacted coastal communities, ground shaking that was locally amplified in some areas and that led to collapse of structures with 118 fatalities in both Greece and Turkey, and wide-ranging geotechnical effects including rockfalls, landsliding, and liquefaction. As a result of the global COVID-19 pandemic, the reconnaissance of this event did not involve the deployment of international teams, as would be typical for an event of this size. Instead, following initial deployments of separate Greek and Turkish teams, the reconnaissance and documentation efforts were managed in a coordinated manner with the assistance of international partners. This coordination ultimately produced a multi-agency joint report published on the 2-month anniversary of the earthquake, and this special issue. This paper provides an overview of the reconnaissance activities undertaken to document the effects of this important event and summarizes key lessons spanning topic areas from seismology to emergency response.

The 2020 Samos (Aegean Sea) M7 earthquake: a normal fault with rupture directivity and near surface slip explaining the tsunami generation and coastal uplift

“…The aftershocks are confined at depths less than 15km in the upper crust, with the Moho located at ~28km in this area. The distribution of the relocated aftershocks depicts the northward dip of the fault and show that other structures inland eastern Samos were activated, as already noted by other researchers (Cetin et al, 2020;Ganas et al, 2020).…”

“…It caused 2 fatalities and 19 minor injuries at Samos Island, but 116 fatalities and over 1,030 injuries in Izmir. The damage in Izmir Bay area (Bayrakli district) was mainly attributed to the amplification of ground shaking at site frequencies in the range 0.7 to 1.6 Hz for both stiff and soft soil sites (Cetin et al, 2020). This earthquake is yet another event along the Turkey-Greece cross border region, severely affecting both nations.…”

“…This earthquake is yet another event along the Turkey-Greece cross border region, severely affecting both nations. Detailed information regarding the seismic history of the region is provided in Cetin et al (2020). Dominant E-W striking normal faults control the northern Samos coastline, the marginal fault of the Samos Basin, is a structure of ~35 km length and of 20-30 km width (Nomikou et al, 2021), inferred from sea topography.…”

“…the Samos Basin Fault (Nomikou et al, 2021) or else catalogued as Kaystrios Fault (Caputo and Pavlides, 2013) or as North Samos Fault (Chatzipetros et al, 2013) that the sequence was associated to. The Samos earthquake predominantly ruptured the western segment of this fault, that had not ruptured in documented historical times (since ~1700) while a number of strong events (1873, M~6.5) may be associated with the eastern segment of this fault (Cetin et al, 2020; see chapter 1).…”

Behavior of RC Beam–Column Joints Strengthened with Modified Reinforcement Techniques

“…In most countries vulnerable to seismic events, pre-seismic codes do not meet present standards for reinforced concrete structures [10]. Earthquakes that have occurred recently (e.g., M7.4 Oaxaca (Mexico), M7.0 Aegean Sea (Turkey-Greece), M6.4 Croatia) have mostly caused failures of masonry buildings, but RC buildings were also, in some cases, heavily damaged [11][12][13]. One reason is that the beam-column joints in moment-resisting RC frame constructions have enough shear strength and ductility [14].…”