Taiwan: Magnitude-7.4 earthquake strikes Hualien County at 07:58 April 3 /update 2

A severe magnitude-7.4 earthquake occurred in Hualien County at around 07:58 April 3. The epicenter was 18 km (11 miles) south-southwest of Hualien City, Taiwan. The tremor occurred at a depth of about 35 km (22 miles), and very strong shaking was likely felt near the epicenter in Hualien County, with strong to moderate shaking likely across the rest of Taiwan. Authorities have rescinded the tsunami warning as the tsunami threat has passed; tsunami waves of 1 meter (3.3 feet) were observed in Hualien, 0.4 meters (1.5 feet) in Chengong, and 0.2 meters (0.7 feet) in Longdong. The Japan Meteorological Agency (JMA) has downgraded the red (middle level on a three-tier scale) tsunami warning for Okinawa Prefecture to a yellow tsunami advisory. Authorities in Japan issued precautionary evacuations for coastal and low-lying areas of Okinawa Prefecture. Tsunami waves of 30 cm (12 inches) were observed on Yonaguni Island and 16 cm (6 inches) on Ishigaki Island.

Significant damage and casualties are likely. It could take several hours until authorities can conduct comprehensive damage assessments, especially in remote areas. A magnitude-6.5 aftershock occurred at 08:11 April 3, a magnitude-5.7 aftershock at 08:35 and 08:46, and a magnitude-5.5 aftershock at 08:43. Numerous other weaker aftershocks have also occurred. Further strong aftershocks are likely over the coming days.

Officials may temporarily shut down transportation infrastructure in the tremor zone to check for damage. Minor disruptions could occur during shutdowns, but service will likely resume quickly if no damage is found. Utility outages are possible where shaking occurs. Reports indicate that the metro systems in Taipei, Taichung, and Kaohsiung cities have been suspended; the suspension is expected to last 40-60 minutes. Several buildings in Hualien City have collapsed. Rescue operations are ongoing. Authorities in Japan instructed all flights scheduled to land at Naha Airport (OKA) to redirect to other airports. Flights scheduled to land at Ishigaki Airport (ISG) were also redirected. The Okinawa Expressway is closed between Kyoda and Naha interchanges.

Tsunamis can be long-duration events, and the threat may persist for hours. Aftershocks could cause additional damage. Cellular networks may be overwhelmed.