Near-source ground motion in the M7.8 Gaziantep (Turkey) earthquake

On the night of February 6, 2023, a major earthquake struck Turkey and nearby Syria, whose moment magnitude (M) was estimated at 7.8 (or 7.7, depending on the data source). It started what can be considered a seismic sequence with thousands of recorded earthquakes with magnitude larger than two, including another M6.7 event (or 6.6) occurring shortly after, and one M7.5 (or 7.6) a day and a half later. The area in the south-eastern part of Turkey hit by the sequence is considered, according to probabilistic models, one of the most hazardous in the wider region. This technical note aims at a preliminary illustration of some features of the shaking, deemed of earthquake engineering relevance. To this aim, it preliminarily analyzes the evolution of the sequence so far and the related ground motion intensity, as estimated from ShakeMap envelopes, then focuses on the largest magnitude event, for which a preliminary model of the source is available, while a supplementary report is provided for the other two events. Based on data available at the time of writing, it is found that the development of the sequence and the recorded ground motions are generally in agreement with available models, although some locations may have experienced peak ground accelerations larger than 1.0 g, and near-source effects, determining pulse-like ground motions, apparently occurred.