[S15] AM-1

[S15-03] Constructing an empirical envelope function of seismic waveforms for the evaluation of EEW in Japan

*Hong Peng¹, Stephen Wu^1,2, Masumi Yamada^3,4 (1. Institute of Statistical Mathematics, 2. The Graduate University for Advanced Studies, 3. Kyoto University, 4. Disaster Prevention Research Institute)

In Japan, earthquake early warning (EEW) system analyzes the data from seismic networks and predicts the seismic intensity (SI) at locations where the strong ground motions are expected to arrive within seconds or minutes. Integrated particle filter (IPF) and propagation of local undamped motion (PLUM) are the two operating EEW systems providing public warnings. IPF predicts the SI through seismic source inversion, while PLUM directly predicts the SI using waveform propagation theory on real-time seismic waveform data. As a result, warnings from IPF are generally faster but less accurate than PLUM. Regarding the hazard assessment, Japan Meteorological Agency (JMA) select the largest SI among the two systems and broadcasts a single warning to the public. In this study, we aim at improving the selection of the final warning by evaluating the performance of the two systems in real-time based on a new empirical envelope function. We fit a double sigmoid function to SI curves extracted from seismic event data, which obtains about 500,000 waveform records from JMA, K-net and KiK-net in the past 20 years. Our preliminary results demonstrated high potential to use such a simple approach as a reliable performance metric for comparing different EEW systems in real-time.