December 7, 2007
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion


Seismic Activity for November 2007


1 Major Seismic Activity

* There was no remarkable activity. to supplementary reports

2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

* There was no remarkable activity. to supplementary reports

(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

(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

(4) Kinki-Chugoku-Shikoku Region

* There was no remarkable activity. to supplementary reports

(5) Kyushu-Okinawa Region

* There was no remarkable activity. to supplementary reports



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.

(reference)

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


- Off-shore east of the Chishima Islands M7.9 on November 15, 2006

- Off-shore east of the Chishima Islands M8.2 on January 13, 2007

- Noto Hanto Earthquake M6.9 on March 25, 2007 (depth approximately 10km)

- Central Mie prefecture M5.4 on April 15, 2007 (depth approximately 15km)

- Off-shore northwest of Miyakojima seismic activity with M6.3, M6.7 and M6.1 on April 20, 2007

- Niigataken Chuetsu-oki Earthquake in 2007 M6.8 on July 16, 2007 (depth approximately 10km)

- Off-shore west of Sakhalin M6.4 on August 2, 2007

- Near the coastal area of Kujukurihama seismic activity with M5.3 on August 16, and M4.8 on August 18, 2007

- Coast of Peru M8.0 on August 16, 2007

-Western Kanagawa prefecture M4.9 on October 1, 2007 (depth approximately 15km)

2 Nationwide Seismic Activity by Region

(1) Hokkaido Region

There is no supplementary information for the Hokkaido region.

(2) Tohoku Region

There is no supplementary information for the Tohoku region.

(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.

"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."

(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].

(5) Kyushu-Okinawa Region

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

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


Reference 1
Earthquakes that are described in the "Evaluation of Seismic Activity" (Monthly Report of Seismic Activity in Japan) have the following features.

  1. Events of M6.0 and greater, or events that have maximum seismic intensity 4 or greater
  2. Onshore events of M4.5 and greater that have maximum seismic intensity 3 or greater
  3. Events under the ocean areas of M5.0 or greater that have maximum seismic intensity 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