Could Surface Precipitations Destabilize a Craton?

The high integrated brittle strength of cratons with a cool and thick lithosphere protects cratonic interiors from tectonic deformation. High strain rates (>10^-15 s^-1) at plate boundaries facilitate enhanced faulting. However, cratons are not immuned from seismic activities. Intraplate earthquakes have caused more fatalities than interplate earthquakes. For example, the 1556 Huaxian earthquake (M 8.0), the deadliest earthquake in human history that killed 830,000 people, occurred in the middle of continental China. Seismic quiescent may in some stable continent relate to short instrumental histories (< ~150 years) with respect to the earthquake cycles (>10⁴ years) and the limited resolution of geodetic surveys for fault motions in stable cratons. The extremely long earthquake cycles in stable continents make it hard to be detected due to surface erosional processes, particularly for those ‘one-off’ events. Classical seismic hazard estimation based on slip deficit calculations may not apply to earthquakes in stable continents when the last destructive earthquake occurred in history is unknown. To quantify the impact of seasonal hydrological cycles on seismicity in stable cratons, we integrate seismic catalogs with GRACE(-FO) data, borehole water levels, precipitation records, and InSAR observations from the Pilbara and Yilgarn cratons in Australia. Our analysis tests whether seismic responses to hydrological stress are consistent across cratons and assesses whether these perturbations induce temporary or permanent changes in craton stability.