GEMS: the opportunity for stress-forecasting all damaging earthquakes worldwide

Abstract

A new understanding of rock deformation allows the accumulation of stress before earthquakes to be monitored by using shear-wave splitting to assess stress-induced changes to microcrack geometry. Using swarms of small earthquakes as the source of shear-waves, such stress accumulations have been recognised with hindsight before some fifteen earthquakes worldwide. On one occasion the time, magnitude, and fault-break of an M 5 earthquake was successfully stress-forecast in a comparatively narrow magnitude/time window. However, suitable swarms of small earthquakes are very uncommon, and routine forecasting requires measurements of controlled-source observations at bore-hole Stress-Monitoring Sites (SMSs). A prototype SMS confirmed that both science and technology are effective for monitoring stress changes before earthquakes, and the sensitivity is such that a network of SMSs, on a 400 km-grid, say, could stress-forecast all M ≥ 5 earthquakes, that is all damaging earthquakes, within the grid. This paper suggests that a Global Earthquake Monitoring System (GEMS) could forecast all damaging earthquakes in both developing and developed countries worldwide