EERI: LUGU, TAIWAN SEPTEMBER 18, 2022, Mw 6.9 EARTHQUAKE

On September 18th, 2022, at 2:44 pm local time, a moment magnitude 6.9 earthquake struck 42.7 km north of Taitung City, Taiwan. The epicentral coordinates reported by the U.S. Geological Survey and the Taiwanese Central Weather Bureau Seismological Center were 23.159°N 121.316°E and 23.14°N 121.20°E, respectively. The USGS reported a hypocenter depth of 10.0 km, whereas the Central Weather Bureau Seismological Center reported a depth of 7.0 km. The earthquake was preceded by a magnitude 6.5 earthquake in the same area 17 hours earlier. There have been several earthquakes of magnitude 5.0 and larger in the sequence. This earthquake caused some geotechnical failures and damage to infrastructure, mainly bridges, railroads, and highways. Damage to buildings was observed, but it was primarily concentrated on older non-ductile structures and non-structural component damage. At least one building collapsed and hundreds more had some damage. The earthquake resulted in at least one death and 171 earthquake related injuries. The earthquake highlighted the vulnerabilities of older non-ductile concrete buildings in seismic regions, concrete bridges, and non-structural building components during an earthquake. This event also highlighted the importance of an earthquake early warning system. The purpose of this Preliminary Virtual Reconnaissance Report (PVRR) is to provide a summary of the characteristics of the event, the seismicity of the impacted region, and an overview of the main effects of the earthquake as collected from publicly available information.