Non-triggering and then triggering of a repeating aftershock sequence in the Dead Sea by the 2023 Kahramanmaraş earthquake pair: Implications for the physics of remote delayed aftershocks

Abstract

Most aftershocks occur in areas experiencing large co-seismic stress changes, yet some occur long after the mainshock in remote lightly-stressed regions. The triggering mechanism of these remote delayed aftershocks is not well understood. Here, we study aftershocks occurring in the Dead Sea (DS) area following the 2023 Mw7.8 and Mw7.6 Kahramanmaraş earthquakes. Most aftershocks cluster along previously quiescent structures off the main the DS fault strand. Visual inspection disclosed three aftershocks instantaneously triggered by the Mw7.6 in the Northern DS basin, and match-filtering revealed a delayed aftershock. Waveform similarity and temporal clustering suggest the northern DS aftershocks re-rupture a stick-slip patch loaded by surrounding creep. Velocity-gradient seismograms show the Mw7.6 exerted larger transient stresses than the Mw7.8, which may explain triggering by the Mw7.6, but not by the Mw7.8. This account of instantaneously-triggered repeaters underscores the role of interactions between aseismic and seismic slip in remote triggering.