Seismic Activity for November 2007

1 Major Seismic Activity

* There was no remarkable activity. to supplementary reports

• Seismic Activity for All of Japan during November 2007 (Magnitude 4.0 and greater)

2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

* There was no remarkable activity. to supplementary reports

• Hokkaido Region

(2) Tohoku Region

* On November 26, there was a M6.0 earthquake at a depth of approximately 45km 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. to supplementary reports

• Tohoku Region
• Earthquake Off-shore of Fukushima Prefecture on November 26

(3) Kanto-Chubu Region

* On November 30, there was a M4.7 earthquake at a depth of approximately 55km off-shore of Ibaraki 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.

* There have been no anomalous changes observed in the GPS data for the Tokai region. to supplementary reports

• Kanto-Chubu Region
• Earthquake Off-shore of Ibaraki Prefecture on November 30
• Continuous GPS Monitoring in the Area from Kakegawa to Omaezaki
• Recent Crustal Movements in the Tokai Region (Horizontal Movements) [Ogata is the fixed reference point] (November 2006–November 2007)
• Crustal Movements in the Tokai Region, Time series, Ogata is the fixed reference point
• Area of Ocean Survey and Seismic Depth Section Along S-2 with the Aftershock Distribution (ERI [OBS])
• Seismic Depth Section Along S-3 with the Aftershock Distribution (ERI [OBS]) and Seismic Depth Section Along S-1 with the Aftershock Distribution (ERI [OBS])

(4) Kinki-Chugoku-Shikoku Region

* There was no remarkable activity. to supplementary reports

• Kinki-Chugoku-Shikoku Region

(5) Kyushu-Okinawa Region

* There was no remarkable activity. to supplementary reports

• Kyushu Region
• Okinawa Region

Supplementary Information to the Evaluation of Seismic Activity for November 2007 by the Earthquake Research Committee

December 7, 2007

1 Major Seismic Activity

The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during November 2007.

• M4.0 or greater: 69 (88 events occurred in October)
• M5.0 or greater: 7 (9 events occurred in October)
• M6.0 or greater: 1 (There has been a total of 22 events for 2007 by the end of November.)

(reference)

• M4.0 or greater: 73 / month (Median number of earthquakes over the past 10 years from 1996 through 2005)
• M5.0 or greater: 9 / month (Median number of earthquakes over the past 30 years from 1976 through 2005)
• M6.0 or greater: 1.4 / month, approximately 17 / year (Average number of earthquakes over the past 80 years from 1926 through 2005)

The following regions have been noted as having significant seismic activity during the period from October 2006 to the end of September 2007.

to the text

2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

There is no supplementary information for the Hokkaido region.

to the text

(2) Tohoku Region

There is no supplementary information for the Tohoku region.

to the text

(3) Kanto-Chubu Region

- Since mid-November, there has been light seismic activity within the crust at a depth of approximately 15km in western Shizuoka prefecture, with the largest earthquake a M3.6 event on December 2.

• Seismic Activity in Western Shizuoka Prefecture

"There have been no anomalous changes observed in the GPS data for the Tokai region.":
(This evaluation is in agreement with the views presented at the procedural meeting on November 26 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, November 26, 2007)

"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. Under central Shizuoka, the seismicity remains at a level lower than normal within the plate, and higher within the crust. In other regions, seismic activity is generally at a normal level.
There were no notable changes observed in crustal movements in the Tokai region and its neighboring areas."

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(4) Kinki-Chugoku-Shikoku Region

- On November 6, there was a M4.1 earthquake at a depth of approximately 10km near the border between Osaka and Nara prefectures [in Nara prefecture].

• Earthquake near the Border between Osaka and Nara Prefectures [in Nara Prefecture] on November 6

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(5) Kyushu-Okinawa Region

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

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[  ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.