The occurred on May 4, 1998 at 08:30 local time (UTC+9) (on May 3 at 23:30 UTC) in the Philippine Sea region with M_w 7.5 (USGS) and M7.7 (JMA). The epicenter was 260 km from Ishigaki Island, Japan, 400 km from Basco, Philippines, and 425 km from Hualian, Taiwan. A small local tsunami of 4 cm was observed on Miyako. The earthquake was felt in the Ryukyu Islands and in parts of eastern Taiwan. The highest intensity was shindo 3 recorded on Yonaguni, Ishigaki, and Miyako.^[1] In 1999, the former Japan Marine Science and Technology Center ( ) (Japan Agency for Marine-Earth Science and Technology (JAMSTEC) ( ) after 2004) conducted an investigation in the region of the source of this earthquake.^[2]

The source of this earthquake was a sinistral (left-lateral) strike-slip fault. It was an inner-plate earthquake inside the Philippine Sea Plate.^[2][3] Such large inner-plate earthquakes inside the Philippine Sea Plate are not very common in this region. This earthquake was the strongest inner-plate earthquake inside the Philippine Sea Plate in the Ryukyu Islands region in 100 years as it occurred.^[4]

References

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