EARLY QUAKE ALERT SYSTEM IN JAPAN FUMBLES
A familiar scene has played out around the country, much to the chagrin of the Japan Meteorological Agency. After an early earthquake warning is issued, startled people brace themselves for the “big one.” They feel a slight wobble, or even nothing at all, and then go about their business as usual.
The agency has improved the technology for issuing accurate and timely warnings for quakes, but the limitations of the system are still clear, Ryo Yamagishi wrote for the Asahi Shimbun on July 26, 2020.
Since April, the agency has issued several early earthquake warnings for regions where the intensity of the quakes was projected at lower 5 on the Japanese scale of 7. The shaking of a lower 5 earthquake makes it difficult to walk.
But almost all the warnings issued since April have proved wrong. For example, an alert was sent at 1:13 p.m. on May 19 during a news program aired by public broadcaster Japan Broadcasting Corp. (NHK). “An earthquake emergency warning has just been issued,” an announcement said during the show. “Please remain alert against strong shaking.” However, the quake’s maximum seismic intensity, which was recorded in Takayama, Gifu Prefecture, was 4.
Aside from the quake in question, six warnings were issued between April 20 and May 19 for tremors originating in areas along the boundary of Gifu and Nagano prefectures in central Japan and in the Kanto region. But none of them was strong enough to hit the lower 5 threshold. The most embarrassing ones were issued on May 11 and May 19. The former was for a quake off Ibaraki Prefecture that was later estimated at an intensity of just 3. The May 19 quake in Gifu Prefecture was predicted to be up to upper 5, but, like the Ibaraki tremor, the actual intensity was 2 levels lower.