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January 10, 2007 |
| There was no remarkable activity. to supplementary reports |
| * | On December 31, there was a M5.0 earthquake at a depth of approximately 45km off-shore southeast of the Nemuro Peninsula. | |
| * | On December 6, there was a M5.0 earthquake at a depth of approximately 30km off-shore of Kushiro. to supplementary reports | |
| * | On December 28, there was a M4.4 earthquake at a depth of approximately 70km off-shore of Miyagi prefecture. to supplementary reports |
| * | On December 4, there was a M4.5 earthquake at a depth of approximately 50km under northeastern Chiba 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 Philippine Sea and Pacific plates. | |
| * | Since December 30, there has been seismic activity with the largest event a M4.7 earthquake under the ocean near Niijima and Kozushima. | |
| * | On December 16, there was a M4.0 earthquake at a depth of approximately 20km under central Shizuoka prefecture. | |
| * | On December 19, there was a M4.4 earthquake at a depth of approximately 15km near the border between Aichi and Gifu prefectures [eastern Mino, Gifu prefecture]. The focal mechanism showed a strike-slip fault with a compression axis in an E-W direction. | |
| * | On December 26, there was a M4.9 earthquake at a depth of approximately 15km under the ocean near Sado. The focal mechanism showed a reverse fault with a compression axis in a N-S direction. | |
| * | There have been no anomalous changes observed in the GPS data for the Tokai region. to supplementary reports | |
| * | There was no remarkable activity. to supplementary reports |
| * | On December 11, there was a M5.7 earthquake off-shore northeast of Amami Oshima. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. to supplementary reports |
| * | On December 26, there was a M7.2 (determined by USGS) earthquake near Taiwan. The focal mechanism showed a normal fault with a tension axis in an ENE-WSW direction. In addition, 8 minutes later, a M7.1 (determined by USGS) earthquake occurred at nearly the same location. to supplementary reports |
| * | On January 5, there was a M4.0 earthquake at a depth of approximately 55km under eastern Mino, Gifu prefecture. |
| * | On January 8, there was a M4.8 earthquake at a depth of approximately 15km in the Chuetsu region, Niigata prefecture. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred within the aftershock region of the 2004 Niigata Chuetsu Earthquake. |
| * | On January 9, there was a M4.7 earthquake at a depth of approximately 10km off-shore of Abashiri. |
| * | On January 9, there was a M4.4 earthquake at a depth of approximately 80km under southern Ibaraki prefecture. |
[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
January 10, 2007
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during December 2006.
| M4.0 or greater: 136 (121 events occurred in November) | |
| M5.0 or greater: 29 (45 events occurred in November) | |
| M6.0 or greater: 3 (There have been a total of 23 events in 2006.) |
Of the events listed above, 53 earthquakes of M4.0 or greater, 18 earthquakes of M5.0 or greater, and 1 earthquake of M6.0 or greater, were associated with the aftershock activity of the earthquake off-shore east of the Chishima Islands on November 15. (In November, 54 earthquakes of M4.0 or greater, 38 earthquakes of M5.0 or greater, and 2 earthquakes of M6.0 or greater occurred.)
(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 December 2005 to the end of November 2006.
| - Hyuganada | M5.5 on March 27, 2006(depth approximately 35km) | |
| - Off-shore east of the Izu Peninsula | seismic activity with M5.8 on April 21 and M4.5 on April 30, 2006 | |
| - Central Oita prefecture | M6.2 on June 12, 2006(depth approximately 150km) | |
| - Off-shore east of the Chishima Islands | M7.9 on November 15, 2006 |
There is no supplementary information for the Hokkaido region.
"On December 28, there was a M4.4 earthquake at a depth of approximately 70km off-shore of Miyagi prefecture.":
This event occurred within the aftershock region of the M7.1 earthquake that occurred on May 26, 2003.
"On December 19, there was a M4.4 earthquake at a depth of approximately 15km near the border between Aichi and Gifu prefectures [eastern Mino, Gifu prefecture]. The focal mechanism showed a strike-slip fault with a compression axis in an E-W direction.":
The aftershock activity immediately after the earthquake was relatively strong. However, it has subsided at the present time.
"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 December 25 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, December 25, 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 remains at a level lower than normal directly under the area from eastern Hamana Lake through central Shizuoka prefecture. 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."
There was additional activity in the Kanto - Chubu region, as follows.
- On December 31, there was a M4.9 earthquake at a depth of approximately 45km off-shore southeast of Chiba prefecture.
There is no supplementary information for the Kinki - Chugoku - Shikoku region.
There is no supplementary information for the Kyushu - Okinawa region.
On December 8, 2006, there was a M6.4 earthquake off-shore east of the Chishima Islands. This event occurred within the aftershock region of the M7.9 earthquake that occurred on November 15.
Reference 1Earthquakes 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. |
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| Reference 2 Information that is described in the "Supplementary Information to the Evaluation" includes: |
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| 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. |