June 11, 2012
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
* On May 24, there was a M6.1 earthquake offshore east of Aomori prefecture. This event had a maximum seismic intensity 5 Upper in Aomori prefecture and caused damage.
* On May 4, there was a M4.5 earthquake at a depth of approximately 85 km under the southern Nemuro region [near the Kunashir Island]. The focal mechanism had a tension axis in an N-S direction. This event occurred within the Pacific plate.
* On May 4, there was a M4.5 earthquake at a depth of approximately 85 km under the southern Nemuro region [near the Kunashir Island]. The focal mechanism had a tension axis in an N-S direction. This event occurred within the Pacific plate.
* On May 24, there was a M6.1 earthquake at a depth of approximately 60 km, offshore east of Aomori prefecture. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred on the boundary between the Pacific and the continental plates.
* On May 18, there was a M4.8 earthquake at a depth of approximately 50 km under southern Ibaraki prefecture. The focal mechanism showed a reverse fault with a compression axis in an NW-SE direction. This event occurred on the boundary between the Philippine Sea and the continental plates.
* On May 27, there was a M6.3 earthquake at a depth of approximately 500 km, offshore west of the Bonin Islands [under the sea near Chichijima]. The focal mechanism had a compression axis in an NW-SE direction. This event occurred within the Pacific plate.
* On May 29, there was a M5.2 earthquake at a depth of approximately 65 km under northwestern Chiba prefecture. The focal mechanism showed a reverse fault with a compression axis in an E-W direction. This event occurred on the boundary between the Philippine Sea and the Pacific plates.
* In the GNSS data for the Tokai region, there have been no changes of activity which are likely to be associated with the Tokai earthquake.
There was no remarkable activity.
* On May 21, there was a M5.1 earthquake at a depth of approximately 90 km, offshore northwest of the Okinawa Main Island. The focal mechanism had a compression axis in an NNW-SSE direction. This event occurred within the Philippine Sea plate.
* On June 1, there was a M5.1 earthquake at a depth of approximately 45 km under northwestern Chiba prefecture [southern Ibaraki prefecture]. The focal mechanism showed a reverse fault with a compression axis in an NNW-SSE direction. This event occurred on the boundary between the Philippine Sea and the continental plates.
* On June 4 at 15:51, there was a M4.4 earthquake at a depth of approximately 10 km in the foot of mountains in southern Miyazaki prefecture. The focal mechanism had a tension axis in a WNW-ESE direction. This event occurred within the crust. On the same day at 14:09, there was a M3.8 earthquake.
* On June 6, there was a M6.3 earthquake offshore east of Chiba prefecture. The focal mechanism showed a strike-slip fault with a compression axis in an N-S direction.
Note: [ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
GNSS (Global Navigation Satellite System) is a general name of satellite
positioning system such as GPS.
June 11, 2012
Earthquake Research Committee
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during May 2012.
(reference)
The following events for the period from May 2011 to late April 2012 have been listed as "Major Seismic Activities" in monthly "Evaluation of Seismic Activitie"
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– Hamadori, Fukushima Prefecture | M5.2 on May 6, 2011 (Depth of approximately 5 km) |
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– Chuetsu Region, Niigata Prefecture | M4.7 on June 2, 2011 (Depth of approximately 5 km) |
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– Offshore Iwate Prefecture | M6.9 on June 23, 2011 (Depth of approximately 35 km) |
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– Central Nagano Prefecture | M5.4 on June 30, 2011 (Depth of approximately 5 km) |
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– Northern Wakayama Prefecture | M5.5 on July 5, 2011 (Depth of approximately 5 km) |
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– Offshore Sanriku | M7.3 on July 10, 2011 |
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– Southern Ibaraki Prefecture | M5.4 on July 15, 2011 (Depth of approximately 65 km) |
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– Suruga Bay | M6.2 on August 1, 2011 (Depth of approximately 25 km) |
| – Offshore Fukushima Prefecture | M6.5 on August 19, 2011 (Depth of approximately 50 km) |
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– Central Hidaka Region | M5.1 on September 7, 2011 (Depth of approximately 10 km) |
| – Northern Ibaraki Prefecture | M5.2 on September 21, 2011 (Depth of approximately 10 km) |
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| – Hamadori, Fukushima Prefecture | M5.4 on September 29, 2011 (Depth of approximately 10 km) |
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| – Kumamoto Region, Kumamoto Prefecture | M4.5 on October 5, 2011 (Depth of approximately 10 km) |
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– Northern Ibaraki Prefecture | M5.3 on November 20, 2011 (Depth of approximately 10 km) |
| – Northern Hiroshima Prefecture | M5.4 on November 21, 2011 (Depth of approximately 10 km |
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| – Offshore Urakawa | M6.2 on November 24, 2011 (Depth of approximately 45 km) |
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– Offshore Fukushima Prefecture | M5.1 on January 23, 2012 (Depth of approximately 50 km) |
| – Eastern Yamanashi Prefecture-Fujigoko | M5.4 on January 28, 2012 (Depth of approximately 20 km) | |
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– Near Sado | M5.7 on February 8, 2012 (Depth of approximately 15 km) |
| – Northern Ibaraki Prefecture | M5.2 on February 19, 2012 (Depth of approximately 5 km) |
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| – Offshore Ibaraki Prefecture | M5.3 on March 1, 2012 (Depth of approximately 55 km) |
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| – Northern Ibaraki Prefecture | M5.4 on March 10, 2012 (Depth of approximately 5 km) |
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| – Offshore Sanriku | M6.9 on March 14, 2012 | |
| – Offshore East of Chiba Prefecture | M6.1 on March 14, 2012 (Depth of approximately 15 km) |
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| – Offshore Iwate Prefecture | M6.6 on March 27, 2012 (Depth of approximately 20 km) |
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| – Offshore Fukushima Prefecture | M5.9 on April 1, 2012 (Depth of approximately 55 km) |
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| – Northeastern Chiba Prefecture | M5.8 on April 29, 2012 (Depth of approximately 50 km) |
There is no supplementary information for the Hokkaido region.
– A series of seismicity which has been seen since mid-March, 2011 has gradually been decaying in the vicinity of the prefectural border of Aizu, Fukushima prefecture and the Okitama region, Yamagata prefecture.
– In the region from Hamadori, Fukushima prefecture through northern Ibaraki prefecture, brisk seismicity has been continuing since the 2011 off the Pacific Coast of Tohoku Earthquake.
– In the aftershock area of the 2011 off the Pacific Coast of Tohoku Earthquake, brisk seismicity has been seen. There is fear that large aftershocks will occur from now on, and there is a possibility that it will be hit by strong shaking and high tsunami. Crustal movements to the east which are thought to be the postseismic deformation have still been observed in a wide area from the Tohoku through the Kanto-Chubu regions, but they have gradually been decaying.
"In the GNSS data for the Tokai region, there have been no changes
of activity which are likely to be associated with the Tokai earthquake":
(This evaluation is in agreement with the views presented at the regular
meeting on May 29 of the Assessment Committee for Areas under Intensified
Measures against Earthquake Disaster (reference below).)
(Reference)
Recent seismic and crustal activity in the Tokai region and its vicinity (Seismological and Volcanological Department, Japan Meteorological Agency, May 29, 2012)
"No changes of activity which are likely to be associated with the Tokai earthquake have been observed until now. (Excerpted))"
There is no supplementary information for the Kinki-Chugoku-Shikoku region.
There is no supplementary information for the Kyushu-Okinawa region.
Reference 1
Earthquakes that are described in the "Evaluation of Seismic Activity" (Monthly Report of Seismic Activity in Japan) have the following features.
Reference 2
Information that is described in the "Supplementary Information to the Evaluation" includes: