Abstract
AbstractA series of earthquakes that struck Taiwan's southern Longitudinal Valley on September 17 and 18, 2022 severely damaged several buildings in Taitung and Hualien. The Chishang earthquake, which had a magnitude of ML 6.8 and a large foreshock with a magnitude of ML 6.6 the day before, was the mainshock in this sequence. The strongest intensity reported in the epicentral region during this earthquake sequence, which was 6 + , is the highest ever recorded since the Central Weather Bureau (CWB, renamed as the Central Weather Administration since September 15, 2023) revised its seismic intensity scale. National Taiwan University (NTU) has operated a low-cost earthquake early warning (EEW) system known as the P-Alert for a decade. In this study, we demonstrate the performance of the P-Alert network during the 2022 Chishang earthquake and the largest foreshock. The P-Alert network plotted shake maps during these earthquakes that displayed various values within 5 min. The high shaking areas on these maps were in good agreement with observed damages during this earthquake, providing valuable insights into rupture directivity, a crucial component of earthquake engineering. Individual P-Alert stations acted as on-site EEW systems and provided a lead time of 3–10 s within the blind zone of CWB. For the ML 6.8 mainshock, there was a lead time of at least 5 s, even up to 10 s, demonstrating their effectiveness in the blind zone. The P-Alert regional EEW system provided the first report about 9 s and 7 s after the mainshock and the largest foreshock occurrence, respectively, with estimated magnitudes of 5.74 and 5.67. The CWB system estimated magnitudes of 6.72 and 6.16 in the first report, respectively, about 7 s and 9 s after the earthquake occurrence. The timeliness of the two systems were not significantly different. Despite the effectiveness of the P-Alert network, data loss due to connection interruptions prompted us to develop a new compact data logger for improved data availability.
Funder
National Science and Technology Council
Publisher
Springer Science and Business Media LLC
Subject
Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Oceanography
Reference38 articles.
1. Chen KH, Toda S, Rau RJ (2008) A leaping, triggered sequence along a segmented fault: the 1951 ML 7.3 Hualien-Taitung earthquake sequence in eastern Taiwan. J Geophys Res Solid Earth. https://doi.org/10.1029/2007JB005048
2. Chen DY, Hsiao NC, Wu YM (2015a) The earthworm based earthquake alarm reporting system in Taiwan. Bull Seismol Soc Am 105(2A):568–579. https://doi.org/10.1785/0120140147
3. Chen DY, Wu YM, Chin TL (2015b) Incorporating low-cost seismometers into the central weather bureau seismic network for earthquake early warning in Taiwan. Terr Atmos Ocean Sci 26(5):503. https://doi.org/10.3319/TAO.2015.04.17.01(T)
4. Chou CC, Wu CL, Chai JF, Yao GC (2023) Reconnaissance Report on Seismic Damage Caused by the 2022 Guanshan and Chihshang Earthquake Sequence, Taiwan, Technical Report of National Center for Research on Earthquake Engineering, NCREE-23-007, 229 pp
5. Hayes GP, Rivera L, Kanamori H (2009) Source inversion of the w-phase: real-time implementation and extension to low magnitudes. Seismol Res Lett. 80(5):817–822. https://doi.org/10.1785/gssrl.80.5.817