December 10, 2009
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion

Seismic Activity for November 2009

1 Major Seismic Activity

There was no remarkable activity.

• Seismic Activity for All of Japan during November 2009 (Magnitude 4.0 and greater)

to supplementary reports

2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

* On November 24, there was a M5.0 earthquake off-shore east of Hokkaido. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction.

• Hokkaido Region
• Earthquake Off-shore East of Hokkaido on November 24

to supplementary reports

(2) Tohoku Region

* On November 21, there was a M4.5 earthquake at a depth of approximately 10km near the border between Fukushima and Tochigi prefectures [in northern Tochigi prefecture].

• Tohoku Region
• Earthquake near the Border between Fukushima and Tochigi prefectures on November 21

to supplementary reports

(3) Kanto-Chubu Region

* On November 4, there was a M5.6 earthquake off-shore west of the Ogasawara Islands [under the ocean area near Chichijima].

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

• Kanto - Chubu Region
• Earthquake Off-shore West of the Ogasawara Islands on November 4
• 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 2008 – November 2009)
• Crustal Movements in the Tokai Region, Time series, Ogata is the fixed reference point (Postseismic movements have been removed)

to supplementary reports

(4) Kinki-Chugoku-Shikoku Region

There was no remarkable activity.

• Kinki-Chugoku-Shikoku Region

to supplementary reports

(5) Kyushu-Okinawa Region

There was no remarkable activity.

• Kyushu Region
• Okinawa Region

to supplementary reports

[  ] were the regional names of the epicenters used in the Japan Meteorological Agency announcement.

Supplementary Information to the Evaluation of Seismic Activity for November 2009 by the Earthquake Research Committee

December 10, 2009

1 Major Seismic Activity

The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during November 2009.

• M4.0 or greater: 59 (73 events occurred in October)
• M5.0 or greater: 4 (12 events occurred in October)
• M6.0 or greater: 0 (There has been a total of 15 events by the end of November in 2009.)

(reference)

• M4.0 or greater: 73 / month (Median number of earthquakes over the past 10 years from 1998 through 2007)
• M5.0 or greater: 9 / month (Median number of earthquakes over the past 35 years from 1973 through 2007)
• M6.0 or greater: 1.4 / month, approximately 17 / year (Average number of earthquakes over the past 84 years from 1924 through 2007)

The following regions have been noted as having major seismic activity during the period from November 2008 to the end of October 2009.

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2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

– On November 19, there was a M4.2 earthquake at a depth of 5km in the Kitami region, Abashiri subprefecture.

• Earthquake in the Kitami Region, Abashiri Subprefecture on November 19

to the text

(2) Tohoku Region

There is no supplementary information for the Tohoku region.

to the text

(3) Kanto-Chubu Region

"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 30 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" (Seismological and Volcanological Department, Japan Meteorological Agency, November 30, 2009)

"So far, there have been no changes of activity which are likely to be associated with the so-called Tokai earthquake.
1. Status of seismicity
The aftershock activity of the earthquake under Suruga Bay on August 11, has been subsiding.
Within the crust under mid-western Shizuoka prefecture, general seismicity has been slightly strong since mid-2005.
There continue to be fewer events within the Philippine Sea plate under the region around Hamana lake.
In other regions, seismic activity is generally at a normal level.

2. Status of crustal movements
There have been no remarkable changes observed over the entire region.
According to the GPS data and leveling results, the trend of long-term subsidence at Omaezaki has been continuing as before."

– On November 22, there were two M3.7 earthquakes at a depth of 10km in the Reinan region, Fukui prefecture. Both focal mechanisms showed reverse faults with compression axes in an E-W direction. These events occurred within the curst.

• Earthquakes in the Reinan Region, Fukui Prefecture on November 22

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(4) Kinki-Chugoku-Shikoku Region

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

to the text

(5) Kyushu-Okinawa Region

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

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