This article came out on the 16th. I didn’t notice it at the time but, come to think of it, I was kind of busy then.

Two thoughts.

First, before the first earthquake hit, I wasn’t under the impression that Kumamoto was particularly vulnerable to earthquakes, as this article indicates that the experts had already assessed it to be. I watch the news in Japanese and read a Japanese newspaper (though not the Kumanichi) so I’m wondering if I missed it or if this possibility just wasn’t talked about that much in the media. I’d be particularly interested to hear what Japanese residents of Kumamoto think about this: Do you think we were adequately warned?

Second, I think this is an interesting explanation of why we are having so many aftershocks:

「Hideki Shimamura, a professor at Musashino Gakuin University, said the shallow depths of the epicenters of the quakes and diverging fault lines are the reasons for the frequent shaking. The epicenters for the magnitude 6.5 quake on Thursday was 11 kilometers below ground and 12 kilometers for the magnitude-7.3 temblor on Saturday. “The same thing happened during the 2004 Niigata Chuetsu earthquake in which the epicenter was also shallow,” said Shimamura. “If the epicenter is about 100 kilometers, there won’t be so many aftershocks.”」

By the way, the media is reporting the number of earthquakes and aftershocks over shindo 1 on the Japanese scale. Personally, I’m more interested in the number at 3 or higher where I live because that’s what I tend to notice (1 and 2 are a bit too mild for me to notice unless I’m sitting very quietly). I just checked the database and found that the Central Ward (Chuo-ku) of Kumamoto where I live has had 50 level 3 or greater quakes since this all started on the 14th. (It was 49 when I first checked but then we had another level 3 quake as I was writing this post.) By contrast, my little corner of Kumamoto had had just two quakes of level 3 or higher intensity in the 5 year period between April 14, 2011 and April 13, 2016 (one each in 2011 and 2015).

– Kirk

The searchable database I referred to is here: http://www.data.jma.go.jp/svd/eqdb/data/shindo/index.php

http://www.japantimes.co.jp/news/2016/04/16/national/big-temblors-no-surprise-to-experts/