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.