Earthquake Early Warning “False” Far observation point Not used for earthquake size estimation August 8 at 6:48
On July 30, the Earthquake Early Warning was announced targeting the Kanto and Tokai areas, but after the shaking of seismic intensity of 1 or more was not observed, the Japan Meteorological Agency observed as a remedial measure far away from the epicenter. I decided not to use the points to estimate the magnitude of the earthquake.
Although the Earthquake Early Warning was announced on the 30th of last month that a strong tremor is expected in a wide range such as Kanto and Tokai, no tremors with seismic intensity of 1 or more were observed, and the Japan Meteorological Agency apologized that it was a false alarm. ..
A subsequent analysis by the Japan Meteorological Agency revealed that a magnitude 5.8 earthquake occurred with the epicenter in the sea near Torishima of the Izu Islands, but based on the observation results off the Boso Peninsula, etc., it was located off the southern part of the Boso Peninsula. It turned out that it was estimated to.
Furthermore, because the relatively large seismic data on the Hahajima Island of the Ogasawara Islands, which is more than 800 km away, was used to estimate the magnitude of the earthquake, the magnitude was 7.3, which was an overestimate.
For this reason, the Japan Meteorological Agency decided to change the system settings so that the data of the observation points more than 700 km from the hypocenter assumed in September will not be used for the magnitude estimation as an immediate improvement measure.
However, the original problem of having estimated that the epicenter of the earthquake that occurred in the sea near Torishima was off the south side of the Boso Peninsula far away, the fact that it has not been solved yet, the Japan Meteorological Agency is considering a countermeasure. I will continue.