Task 4: Integrating fault data and prior earthquake scenarios and Ground Motion in Earthquake Early Warning
Leaders: Harsha BHAT (ENS Paris) and Maren BÖSE (ETH) – Partners involved: IFSTTAR, ENS, ETH, Caltech, Géoazur
Earthquake Early Warning (EEW) needs rapid earthquake detections and accurate shaking forecasts. Large earthquakes present the best opportunities for EEW as large areas, including those far from the epicenter, are affected by damaging shaking and could receive a warning of more than one minute. In regions with dense seismic and/or geodetic real-time networks, present EEW algorithms can determine hypocenters locations, (lower bound) magnitudes, and (lower bound) rupture dimensions within seconds of event initiation. One common assumption, however, is that the state of the seismic source (at the time when an alert is issued) is close to final, which means that « prediction » refers to future Ground Motions, but does not account for the possibility that the rupture has not finished yet.
A more accurate prediction of the anticipated shaking should thus include plausible worst-case scenarios for the evolution of an on-going fault rupture, such as on how large the rupture can eventually grow. The outputs from Tasks 2&3 will enable us to anticipate –for a given hypocenter location and identified causative fault whose macroscopic properties are known– the direction of rupture propagation, the maximum possible extent of the rupture, the maximum slip and its location along the rupture, and the associated Ground Motions (Task 3). These constraints will tell us which areas could experience more damaging shaking and should receive a warning.