Matsushiro earthquake swarm

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Epicenters distribution
(August 1965 ~ May 1967)

The Matsushiro earthquake swarm (

earthquake swarms
.

Overview

The Matsushiro swarm lasted from 1965 to 1967 and generated about 1 million earthquakes.[2] The total sum of energy from all the tremors was approximately equivalent to an M6.4 earthquake.[3][4] This swarm had the peculiarity to be sited just under a seismological observatory installed in 1947 in a decommissioned military tunnel. It began in August 1965 with three earthquakes too weak to be felt, but three months later, a hundred earthquakes could be felt daily. On 17 April 1966, the observatory recorded 6,780 earthquakes, with 585 of them having a magnitude large enough to be felt, which meant that one earthquake could be felt every 2 minutes 30 seconds on average.[5] The phenomenon was clearly identified as linked to a magma uplift, perhaps initiated by the 1964 Niigata earthquake which happened one year before.[6]

References

  1. ^ 日本国語大辞典,デジタル大辞泉,世界大百科事典内言及, 日本大百科全書(ニッポニカ),精選版. "松代群発地震とは". コトバンク (in Japanese). Retrieved 2021-05-26.{{cite web}}: CS1 maint: multiple names: authors list (link)
  2. ^ "松代群発地震(1965年8月3日) | 災害カレンダー". Yahoo!天気・災害 (in Japanese). Retrieved 2021-05-26.
  3. ^ "松代群発地震_松代地震観測所". www.data.jma.go.jp. Retrieved 2021-05-26.
  4. ^ "Matsushiro earthquake swarm". www.data.jma.go.jp. Retrieved 2017-10-31.
  5. .