Earthquakes in the Shadows: Why Aftershocks Occur at Surprising Locations

Abstract For decades there has been a debate about the relative effects of dynamic versus static stress triggering aftershocks. According to Coulomb change hypothesis, aftershocks should not occur in shadows—regions where reduced. We show that shadows substantially influence aftershock occurrence following three M ? 7 California mainshocks. Within modeled shadows, rate is an order magnitude lower than increase regions. However, earthquake does decrease below background rate, as predicted by models. Aftershocks exhibit different spatial–temporal characteristics from The decays power law with distance mainshock, consistent simple model triggering. These begin burst activity during first few days after also Our interpretation sequences are combined result and triggering, estimated ?34% due ?66%