Utilization of Station Clusters for Earthquake Early Warning

Andrew B. Lockman and Richard M. Allen
University of Wisconsin-Madison

AGU Fall Meeting 2004

Earthquakes from three seismically active regions demonstrate a scaling relation between event magnitude and the predominant period of the P-wave, and confirm the potential of using P-wave arrivals to rapidly estimate event magnitude and issue a warning prior to the onset of damaging ground motion. Results show that using the scaling relations to calculate the magnitude produce errors that decrease as more stations record the earthquake, with an average error of ±0.5 magnitude units once four stations register the predominant period. This suggests that the use of P-wave detection for earthquake early warning does not require a dense seismic network, and that a small cluster of broadband seismic instruments is sufficient to provide a useful warning of impending ground motion.

Our study focuses on both rapid magnitude determination and earthquake location using P-wave arrivals at station clusters that may not encompass the epicenter. We begin by analyzing the capacity of the closest single station to determine the distance and depth of an earthquake, and investigate how the accuracy of these estimates change as more stations record the event. Not surprisingly, there is significant inaccuracy in earthquake location using only one station, but the ability to locate the epicenter, hypocenter, and origin time increases significantly as more stations record the event.