DAS-based empirical amplitude prediction for earthquake early warning along Japan's Shinkansen railway

Abstract

Japan's Shinkansen (bullet train) system has faced concerns regarding potential earthquakes occurring near its railways, motivating seismologists and Japan Railways Group (JR) leaders to keep developing its independent early warning system. Since the inception of Distributed Acoustic Sensing (DAS) technology, which transforms telecommunications fiber optic cables into seismometers, it has proven reliable in retrieving earthquake information and shows strong potential for early warning. This paper presents strategies demonstrating the effective use of DAS for real-time earthquake monitoring along the Shinkansen system. To accomplish this objective, we conducted an analysis of a specific segment of the JR Central Shinkansen line, spanning from Atami to Tokyo Station. We calibrated body-wave empirical scaling relations following two distinct approaches: 1) a method that determines earthquake location and magnitude to predict the S-wave peak strain-rate amplitude (PSRA), and 2) an empirical relationship between S- and P-wave amplitudes, allowing PSRA prediction without prior earthquake location information. All these procedures can be completed within the initial 3-4 s following the first P-wave arrival. Consequently, our methods represent a comprehensive early warning procedure.