Effect of large-scale surface water level fluctuations on earthquake recurrence interval under strike-slip faulting

Abstract

While tectonic motion is seen as a primary cause of the earthquakes, the effects of water level fluctuations on geological rates of seismicity have not been studied in depth. Can fluctuations of tens to hundreds of meters significantly perturb local fault systems and modify the behaviour of their seismic cycles? Our novel theoretical modelling can explain variability in the paleoseismic rates of large earthquakes rupturing strike-slip faults, by large-scale water level fluctuations in basins overlying the faults. We demonstrate that water level increase can significantly affect effective stresses at the faults, generate immediate and delayed seismic responses, and accelerate seismic events under strike-slip faulting regime. Both, water level induced stress change and hence seismic recurrence interval, are significantly affected by an interplay between hydro-mechanical properties of the fault zone. Our modelling demonstrates that water level fluctuation of historic water bodies in the tectonic depression of the Dead Sea fault could have triggered changes in the paleo-seismic rates.