May 10, 2006 Headquarters for Earthquake Research Promotion Earthquake Research Committee

	- Northeastern Chiba prefecture	M6.1 on April 11, 2005 (depth approximately 50km)
	- Amakusa Ashikita region, Kumamoto prefecture	M4.8 on June 3, 2005 (depth approximately 10km)
	- Chuetsu region, Niigata prefecture	M5.0 on June 20, 2005 (depth approximately 15km)
	- Northwestern Chiba prefecture	M6.0 on July 23, 2005 (depth approximately 75km)
	- Off-shore of Miyagi prefecture	M7.2 on August 16, 2005 (depth approximately 40km)
	- Chuetsu region, Niigata prefecture	M5.0 on August 21, 2005 (depth approximately 15km)
	- Off-shore of Ibaraki prefecture	M6.3 on October 19, 2005 (depth approximately 50km)
	- Off-shore of Sanriku	M7.2 on November 15, 2005
	- Hyuganada	M5.5 on March 27, 2006 (depth approximately 35km)

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2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

“On April 13, there was a M5.3 earthquake at a depth of approximately 45km off-shore of Urakawa. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred at the boundary between the Pacific and the continental plates.” In addition to that event, there was a M4.6 earthquake on April 9, also M4.5 and M4.6 earthquakes on April 26 off-shore of Urakawa.

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(2) Tohoku Region

- On April 22, there was a M4.6 earthquake at a depth of approximately 65km off-shore of Miyagi prefecture (maximum seismic intensity 4). This event occurred within the Pacific plate.

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(3) Kanto-Chubu Region

"The long-term changes that have been observed since 2001 in the continuous GPS data in the Tokai region, appear to have nearly stopped recently." :
A According to the GPS data, the Pacific side of the Tokai-Chubu region maintained a steady rate with movement to the WNW, consistent with the subduction of the Philippine Sea plate toward the northwest. The results, from observations in the area centered on western Shizuoka prefecture, have been showing a trend of moderate change since about April 2001. This long-term change seems to have nearly stopped recently.
  (This evaluation is in agreement with the views presented at the procedural meeting on April 24 of the Assessment Committee for Areas under Intensified Measures against Earthquake Disaster. (see reference below))


(reference) "Recent seismic and crustal activity in the Tokai region and its vicinity" (Japan Meteorological Agency, Department of Seismology and Volcanology, April 24, 2006)

"So far, there have been no changes of activity which are likely to be associated with the so-called Tokai earthquake.
 There was no remarkable seismic activity in general. The seismicity continues at a level lower than normal directly under Hamana lake. In other regions, seismic activity is generally at a normal level.
  The long-term crustal movements from the slow slip at the plate boundary in the Tokai region and its neighboring area, seem to have nearly stopped recently."

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(4) Kinki-Chugoku-Shikoku Region

- There is no supplementary information for the Kinki - Chugoku - Shikoku region.

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(5) Kyushu-Okinawa Region

- There is no supplementary information for the Kyushu - Okinawa region.

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Reference 1 Earthquakes that are described in the "Evaluation of Seismic Activity"(Monthly Report of Seismic Activity in Japan) are events of M6.0 and greater, or events of M4.0 and greater (M5.0 or greater off-shore) that have maximum intensity of 3 or greater. Reference 2 Information that is described in the "Supplementary Information to the Evaluation" includes: 1) Reference information related to seismic activity described in the "Evaluation of Seismic Activity" 2) Recent earthquake activity over the past year related to the events described in "Major Seismic Activity" in the "Evaluation of Seismic Activity" 3) Seismic activity that has been evaluated, but not included in the "Evaluation of Seismic Activity" because it is within normal bounds and not prominent.