Traditional seismic hazard analyses underestimate hazard levels when compared to observations from the 2023 Kahramanmaras earthquakes

Abstract

A sequence of two major earthquakes, Mw7.8 Pazarcik, and Mw7.5 Elbistan, struck Southeastern Turkey in February 2023. The large magnitudes of the earthquakes and the short time between the two events raised questions about whether this sequence was an extremely rare disaster. Here, based on prior knowledge, we perform seismic hazard assessment for the region to estimate exceedance probabilities of observed magnitudes and ground motions. We discuss that many regional studies indicated the seismic gap in the area but with lower magnitude estimations. Observed ground motions generally agree with empirical models for the Pazarcik event. However, some records with high amplitudes exceed the highest observed amplitudes in an extensive database of shallow crustal earthquakes. We observe a notable trend of residuals for the Elbistan earthquake, leading to underestimation at long periods. We discuss potential advances in science for better characterization of such major earthquakes in the future.