Geotechnical Assessment of the Pore Water Pressure Build-up in Izmir During the October 30, 2020, Samos Earthquake

On October 30, 2020, a damaging earthquake of moment magnitude 6.6 struck about 14 km northeast of the island of Samos, Greece, and about 70 km from the center of the city of Izmir in Turkey. Even though the epicenter was relatively far away, the effects of the seismic event in the highly populated city center of Izmir were destructive causing over 100 fatalities and significant structural damage. Apart from the site effects that characterized this earthquake, a few liquefaction manifestations were observed during the event. This paper documented the pore water pressure build-up observed in the Bayrakli district after the October 30, 2020 earthquake. Approximate properties of the foundation soils were defined based on a fragmentary reconstruction of the field investigation before the construction of the building. The safety factor against liquefaction was then estimated and it was consistent with the absence of liquefaction manifestation in the area. Simplified prediction of the expected excess pore water pressure based on a simple relationship as a function of safety factor allowed preliminary assessment of the mechanism that is behind the observed phenomena. The proposed methodology is particularly convenient for rapid screening of the expected earthquake-induced effects since it can be directly applied to the safety factor without the identification of additional input data.