Rapid Estimation of Ground Motions
Immediately after a major earthquake, emergency responders and operators of lifeline systems in the affected area need guidance as to the likely distribution of damage. In areas that are densely instrumented with a network of seismometers, the measured distribution of strong ground shaking can be rapidly assembled and broadcasted as an indirect measure of likely damage. In sparsely instrumented locations, however, insufficient empirical data may be available. To supplement such data, new methods make it possible to automatically determine finite-source parameters of earthquakes such as the causative fault plane characteristics and rupture velocity. These source parameters are then used to simulate near-fault ground motions for areas where there are no nearby recording instruments. This process can be carried out automatically, to produce and distribute estimates of shaking within 30 minutes of the event, and can then be reviewed and updated by seismologists in real time. The process is aided by previous PEER studies aimed at improving simulation technologies. This is an important contribution toward the objective of near-real-time reporting of earthquake shaking hazard, and has been provided to ShakeMap V2.x software for widespread application.