Nov. 9, 2005 Headquarters for Earthquake Research Promotion Earthquake Research Committee

	- Southern Ibaraki prefecture	M5.7 on October 6, 2004 (depth approximately 65km)
	- Ocean area near Yonaguni Island	M6.6 on October 15, 2004
	- Chuetsu region, Niigata prefecture (2004 Niigata Chuetsu Earthquake)
		M6.8 on October 23, 2004 (depth approximately 10km)
	- Off-shore of Kushiro	M7.1 on November 29, 2004 (depth approximately 50km)
	- Southern Rumoi subprefecture	M6.1 on December 14, 2004 (depth approximately 10km)
	- Off-shore southeast of the Boso Peninsula (near the triple junction of the plates)
		M6.8 on January 19, 2005
	- Southern Ibaraki prefecture	M5.4 on February 16, 2005 (depth approximately 45km)
	- Off-shore west of Fukuoka prefecture
		M7.0 on March 20, 2005 (depth approximately 10km)
	- 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)

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2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

- There is no supplementary information for the Hokkaido region.

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(2) Tohoku Region

"On October 22, there was a M5.6 earthquake at a depth of approximately 50km off-shore of Fukushima prefecture. 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 this vicinity, M5.5-6.0 level earthquakes have occurred about once every ten years since August 1923.

"On October 18, there was a M5.4 earthquake at a depth of approximately 10km off-shore west of Aomori prefecture. Two minutes later, a M5.3 earthquake occurred at nearly the same location. The aftershock activity started to decline from October 19, and it is mostly subsiding."
These earthquakes occurred in the central area of the aftershock region of the 1983 Mid-Japan Sea Earthquake (M7.7).

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(3) Kanto-Chubu Region

"On October 16, there was a M5.1 earthquake at a depth of approximately 45km under southern Ibaraki prefecture. (excerpted) Also on October 31, there was a M4.2 earthquake at a depth of approximately 50km to the northwest of this earthquake."
In this vicinity, there was a M5.3 earthquake (maximum seismic intensity 5 Upper) on February 16, and a M5.0 on July 28.

"The long-term changes that have been observed since 2001 in the continuous GPS data in the Tokai region, are still continuing, however recently they appear to be slightly diminishing."
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 trend has been continuing in October, 2005, however, recently there seems to be a slight decrease in the change.
(This evaluation is in agreement with the views presented at the procedural meeting on October 31 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, October 31, 2005)

" 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.
In the Tokai region and its neighboring area, the long-term crustal movements from the slow slip at the plate boundary is continuing, however, recently there seems to be a slight decrease in the change. "

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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

- The weak seismicity that increased temporarily in the Chikuhou region, Fukuoka prefecture on October 2, has almost subsided at present, although there was slight activity in mid-October. The largest earthquake so far was a M2.8 event on October 2.

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(6) Other Region

- On October 15, there was a M6.4 earthquake in the Chishima Islands

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Supplement

-	On November 1, there was a M4.3 earthquake at a depth of approximately 45km under the Kii Strait.
-	On November 4, there was a M4.8 earthquake at a depth of approximately 25km off-shore of Niigata prefecture.

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.