[S-SS05] Advancements in Regional Seismic Networks: Operations, Applications, and Development

[SSS05-07] Seismic networks and monitoring at CWA in Taiwan

★Invited Papers

*Nai-Chi Hsiao¹、Da-Yi Chen¹、Chih-Wen Kan¹、Chun-Wei Ho¹、Guan-Yi Song¹、Yu-Hsuan Chang¹、Kuei-Chih Liu¹ (1.Central Weather Administration, Taiwan)

キーワード：CWASN, TSMIP, earthquake catalogue, strong-motion record, felt earthquake rapid reporting

The Central Weather Administration (CWA), regulated from the original Central Weather Bureau (CWB) due to organizational transformation, is the government agency responsible for earthquake monitoring and reporting in Taiwan. In the years of early 1990s, the CWA has begun to implement modern seismic networks and operations for earthquake monitoring. At that time hundreds of seismic stations were built. While 1999 Magnitude 7.6 Chichi earthquake struck Taiwan, the quake information was automatically determined and send to dedicated users by Email and pager in 102 second after occurrence. The information was very important for emergent response, and the performance of rapid reporting was a milestone of earthquake monitoring in the world. At present, two major seismic networks including the Central Weather Administration Seismographic Network (CWASN) and the Taiwan Strong Motion Instrumentation Program network (TSMIP) are in operation. The main purpose of the CWASN is to observe seismicity around Taiwan region and collect seismic waveforms for seismic related studies and applications. There are three types of seismographs installed in field stations, including short period seismographs, accelerographs, and broadband seismographs, which are co-site or individual installed. The resolution of sensors is 24-bit and the sampling rate is 100 Hz. At present, totally about 200 stations are constructed and distributed with 20 km averaged spacing, including 90 downhole and few ocean bottom seismic stations. Through the daily acquisitions and operations since 1991, we now have a complete earthquake catalogue composed of more than 750,000 events. The valuable data are not only utilized to understand the seismic activities, the seismo-tectonic around Taiwan region were detailed researched as well. The TSMIP network is a dense network with strong-motion stations installed over the whole island, particularly on the urban areas. The numerous strong-motion data collected from 1991 provide us very important sources to understand the shaking characteristics during strong earthquake. Currently, there are more than 700 free-field stations. Following the progress on instrumentation, the resolution of sensors is gradually upgraded to 24 bits. Till now, more than 200,000 strong-motion records above 26,000 strong events are collected, and these data were widely applied for the research of strong-motion seismology and earthquake engineering. The CWASN and TSMIP have been also used as the framework developing systems and operations of felt earthquake rapid reporting in Taiwan. While a significant earthquake occurred in or very near Taiwan, the earthquake early warning (EEW) system can acquire the information and issue the warning message less than 10 seconds averagely. Then, the general public could be notified through the message from Internet applications, Cell Broadcast (CB) on mobile device, TV, and so forth. About 5 minutes later, an official report is generated by earthquake report releasing system. Quick confirmed earthquake report is crucial for the emergent responses of society, and meanwhile, reduce the social panic effectively. Besides, more detailed and observed seismic intensities around strong shaking areas could be quickly provided by the township intensity reporting system. Consequently, the reporting capability of felt earthquake information for seismic hazard mitigation is effectively strengthened.