Evaluating the Usefulness of Earthquake Early Warning for a California Rail System

Abstract:

While earthquake early warning (EEW) has been utilized by Japan Railways (JR) since 1966, public EEW in California only began rolling out at the end of 2018. There are several important differences between U.S. rail systems and JR’s Shinkansen bullet trains. On one hand, U.S. trains travel much slower than bullet trains and can be stopped sooner. On the other hand, seismic hazard in California is dominated by continental faults such that hazardous earthquakes rupture much closer to railways than the subduction zone events that contribute significantly to seismic hazard in Japan, and thus warning times will tend to be shorter in California. We have created a framework for evaluating the effectiveness of EEW system designs and, by analyzing a 1,000-year chronology of scenario California earthquake ruptures, we have explored how effective EEW might be for California rail systems and how it can best be utilized. We demonstrate that there is significant potential for EEW to limit trains’ exposure to damaged tracks. Even so, EEW’s greatest benefits may be psychological (in terms of reassuring the ridership) or as a training opportunity for rail systems to practice earthquake response. Real-world use of our EEW evaluation framework to make actionable decisions on warning system design will be highly dependent on the specific application. Each rail system must consider and assign values (including monetary and societal consideration) to the costs associated with precautionary stops and the benefit from slowing trains when damaging shaking occurs.