Development of earthquake early warning system in Taiwan

Abstract

With the implementation of a real‐time strong‐motion network by the Central Weather Bureau (CWB), an earthquake early warning (EEW) system has been developed in Taiwan. In order to shorten the earthquake response time, a virtual sub‐network method based on the regional early warning approach was utilized at first stage. Since 2001, this EEW system has responded to a total of 225 events with magnitude greater than 4.5 occurred inland or off the coast of Taiwan. The system is capable of issuing an earthquake report within 20 sec of its occurrence with good magnitude estimations for events up to magnitude 6.5. Currently, a P‐wave method is adopted by the CWB system. Base on the results from 596 M ≥ 4.0 earthquakes recorded by the real‐time strong‐motion network, we found that peak displacement amplitudes from initial P waves ( P d ) can be used for the identification of M ≥ 6.0 events. Characteristic periods τ c and τ p max of the initial P waves can be used for magnitude determination with an uncertainty less than 0.4. We expect to achieve a 10‐second response time by the EEW system in Taiwan in the near future.