Jiji Press TOKYO (Jiji Press) — The Japan Meteorological Agency said Friday that there was a miscalculation behind its emergency warning on that day of a strong earthquake off the coast of Ibaraki Prefecture, which was followed by no major earthquake.
An earthquake measuring up to 3 on the Japanese seismic intensity scale of 7 occurred off the prefecture at 11:02 a.m., while another earthquake also registering up to 3 took place in the central prefecture of Toyama around the same time, according to the agency.
But the agency’s system to issue emergency quake warnings recognized the two earthquakes as a single temblor, leading to the emergency warning.
The early warning affected public transportation in the Tokyo metropolitan area. Tokyo Metro Co. suspended train operations for three minutes.
The agency issues such alerts when it predicts an earthquake of lower 5 or stronger on the Japanese scale.
The alerts are based chiefly on seismometer data and are issued in order to minimize damage.
“As a result [of the mixed data], the system overestimated the quakes,” said agency official Seiichiro Honda, who is in charge of the development of earthquake prediction models. “We’ll consider ways to improve the system,” he added.Speech