TAIPEI (Taiwan News) — Experts warned that aftershocks of up to magnitude 6 could strike Taiwan this week after a powerful offshore earthquake rattled the island late Saturday, per CNA.

A magnitude 7.0 earthquake struck off the coast of Yilan County at 11:05 p.m., according to the Central Weather Administration, which said aftershocks measuring between magnitude 5.5 and 6.0 could be felt over the next three days to one week.

The CWA’s Seismological Center said the quake was the third magnitude 7 earthquake to affect Taiwan in the past 26 years. A similar earthquake on Sept. 21, 1999, killed more than 2,400 people and caused widespread destruction, while the most recent quake of that scale on April 3, 2024, left 20 people dead and more than 1,000 injured.

According to the CWA, the epicenter of Saturday’s earthquake was offshore, about 32.3 kilometers east of the Yilan County Government, at a depth of 72.8 kilometers. Multiple areas across Taiwan recorded a maximum seismic intensity of 4. Shaking lasted about 21 seconds in Hualien and roughly 10 seconds in northern Taiwan.

Chen Da-yi (陳達毅), section chief of the CWA Seismological Center, told a late-night press conference that the earthquake was caused by the northward subduction of the Philippine Sea Plate colliding with the Eurasian Plate. He said the mechanism was similar to a magnitude 6.1 earthquake that struck off the coast of Yilan on Aug. 27 this year.

“Saturday’s quake was felt across Taiwan, but because it occurred at a considerable depth and its epicenter was offshore, it was relatively unlikely to cause serious damage,” Chen said. He added that areas north of Taichung experienced a maximum intensity of 4, while southern regions recorded intensities of 3 and 2.

Chen said a national-level earthquake alert was issued 15.2 seconds after the quake, covering nearly all counties and cities in Taiwan. A second alert followed 16.3 seconds later, targeting Pingtung County and outlying islands.

He urged the public to remain vigilant for aftershocks of magnitude 5.5 to 6.0 that could occur within the next week.