What is the cause of foreshocks?

Foreshocks are smaller seismic events that occur in the same region before a larger earthquake, often referred to as the mainshock. Their exact cause is not fully understood, but they are believed to result from the buildup of stress along geological faults as tectonic plates move. This stress can lead to smaller fractures or slips in the crust, which release energy and manifest as foreshocks. The occurrence of foreshocks can sometimes serve as a precursor to a larger seismic event, though not always predictably.