Earthquake Early Warning and Engineering Application Prospects

Abstract

The foreseeable future of Earthquake Early Warning Systems (EEWS) is their use as a tool for real-time seismic risk management and mitigation. The applicability potential of EEWS seems to be more related to the immediate activation of safety measures for critical systems rather than as a massive alert to the public. Evacuation of buildings requires warning times which are unlikely to be available in many urbanized areas threatened by seismic hazard, whereas the protection of critical systems may still significantly help to reduce the losses subsequent to a catastrophic event and to increase the resiliency of communities to earthquakes.

Real-Time Seismology (RTS), which consists of methods and procedures for the rapid estimation of earthquake and ensuing ground motion features based on measurements made on the first few seconds of the P-waves, is the focus of a great deal of research. In principle, it may boost the potential of regional seismic sensor networks for site-specific applications, in other words: hybrid EEW. Thus the next challenge of early warning and earthquake engineering is geographically distributed seismic networks for the protection of several critical systems and lifelines at the same time. The key issue is related to uncertainty in the estimation of the event’s features. Therefore, the performance target and feasibility factor of such an EEWS is no longer only to maximize the warning time but also calibrate, in a full probabilistic approach, the alarm thresholds and the decisional rules in order to maximize loss reduction following the decision. This paper reviews and discusses some issues raised for hybrid EEWS in the light of performance-based earthquake engineering (PBEE) for risk reduction applications.