Magnitude 5 aftershocks could follow New Taipei quake: CWA

Taipei, July 27 (CNA) Aftershocks of up to magnitude 5 could occur within a week of the earthquake that struck northern Taiwan on Sunday night, though they are unlikely to be strongly felt due to their depth, the Central Weather Administration (CWA) said.

The magnitude 5.6 earthquake struck at 8:36 p.m., with its epicenter located in New Taipei's Shuangxi District at a depth of 95.7 kilometers. The quake registered an intensity of 3 on Taiwan's seven-tier intensity scale in Yilan County, New Taipei, Taipei, Taoyuan, Hsinchu County, Hualien County, Taichung and Miaoli County.

According to CWA Seismological Center Director Wu Chien-fu (吳健富), the earthquake was caused by the subduction of the Philippine Sea Plate.

As the plate extends northward from waters off Hualien and descends at an angle to a depth of about 90 to 100 kilometers, earthquakes can occur beneath a broad area stretching from waters off Yilan to New Taipei and Taipei, Wu explained.

He said aftershocks measuring around magnitude 4.5 to 5 cannot be ruled out within the next week. However, because they would occur at considerable depths, much of the seismic energy would be absorbed before reaching the surface, resulting in a surface intensity of only 1 to 2, likely making them barely noticeable to the public.

The earthquake on Sunday night also prompted the CWA to issue Public Warning System (PWS) alerts for Yilan County, Taoyuan, Keelung, Taipei and New Taipei.

Wu said that because the quake occurred deep underground, surface monitoring stations needed to receive sufficient signals before processing the data, meaning the alerts were issued about 17 seconds after the quake and the timing of the warnings and the tremors felt by the public varied slightly among areas.