News Two small quakes make one big

[thomas]

This was quite disturbing yesterday: we had three devices going off at the same time, but the quake never materialised. Fortunately, I guess.

The big one last night went unannounced though.

That's shindo, not magnitude.

Earthquake warnings leave Kanto jolted, but the big shake never came

Across the Kanto region and in parts of Fukushima Prefecture, alarms suddenly rang out at 11:02 a.m. Friday from cellphones and public speakers. "Emergency earthquake warning," the text of the cellphone alert from the Meteorological Agency read. "An earthquake has occurred off the coast of Ibaraki. Prepare for strong shaking."

But the jolt never came to the region. The agency had estimated that a magnitude 6.4 earthquake would hit off the coast of Ibaraki Prefecture. In fact, that quake was magnitude 4.4 and 3 on the Japanese intensity scale. But at the same time, a second quake hit Toyama Prefecture, this one a magnitude 3.9 that also measured 3 on the Japanese scale. The erroneous warning — and unnerving alarms — came as a result of the two quakes being processed by the prediction system as one event, a statement released by the Meteorological Agency said. The agency said it will further investigate the incident and make efforts to improve the system.

Source

Simultaneous small quakes in Japan trigger emergency warning - Japan Today

 

[Mike Cash]

I also got the warning while sitting seaside down at the docks in Tokyo yesterday. I clicked NHK radio on and got reports of a shindo 3 quake and wondered what in hell all the fuss was over a 3. Then they announced that the epicenter of the quake was off the coast of Sendai or somewhere off the Pacific coast, I forget exactly where....and then a few seconds later the epicenter had jumped to off the coast of Toyama in the Sea of Japan. They had some rather confused announcing going on for a while.

I was surprised that there was nothing about that big rocker after midnight. That thing shook the hell out out my truck.

 

[Lomaster]

It reminds me how Ministry of Emergency Situations of Russia failed to notify the population of impending calamities on several occasions. After being criticized for that, the Ministry began issuing warnings in spam-like manner even for such "calamities" as a slight breeze and drizzle (should i mention that often times the warnings don't manifest at all?)
Perhaps that's the case with 気象庁 too? "Better safe than sorry" approach.