More than 60 percent of the early warnings issued by the Meteorological Agency since last year's March 11 earthquake were inappropriate as they included small quakes registering 2 or less on the Japanese seismic intensity scale to 7, the agency said Thursday.
The agency has issued 104 early warnings since last year's disaster struck, but 63 of them, were inappropriate, agency officials said.
While the early warning system is aimed at alerting the public to the possibility of a strong quake, inappropriate warnings were issued as the system calculated a number of quakes that occurred almost simultaneously, as one, the agency said.
After the warning system's software was upgraded last August, seven of the 17 warnings were judged to be inappropriate, the agency added. The frequency of incorrect warnings has thus dropped to just over 40 percent in percentage terms.
The agency also said its survey of 817 residents in the three prefectures that experienced especially strong quakes — Iwate, Miyagi and Fukushima — showed that 90 percent of them found the early warnings useful.