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February 14, 2007 |
| On January 13, there was a M8.2 earthquake off-shore east of the Chishima Islands. This event caused tsunamis from the coast of the Okhotsk Sea and along the whole Pacific coast (of Japan). to supplementary reports |
| * | On January 9, there was a M4.7 earthquake at a depth of approximately 10km off-shore of Abashiri. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. to supplementary reports | |
| * | There was no remarkable activity. to supplementary reports |
| * | On January 4, there was a M4.2 earthquake at a depth of approximately 55km off-shore of Ibaraki prefecture. | |
| * | On January 9, there was a M4.3 earthquake at a depth of approximately 80km near the border of Saitama, Chiba and Ibaraki prefectures [southern Ibaraki prefecture]. | |
| * | On January 16, there was a M5.8 earthquake at a depth of approximately 180km under the Izu region, Shizuoka prefecture [eastern Shizuoka prefecture]. The focal mechanism had a compression axis in the direction of the subducting plate. This event occurred within the Pacific plate. | |
| * | On January 5, there was a M4.0 earthquake at a depth of approximately 55km under eastern Mino, Gifu prefecture. | |
| * | On January 22, there was a M4.5 earthquake at a depth of approximately 15km near the border of Fukui and Gifu prefectures [Reihoku, Fukui prefecture]. The focal mechanism showed a strike-slip fault with a compression axis in a WNW-ESE direction. | |
| * | 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. | |
| * | 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 |
| * | There was no remarkable activity. to supplementary reports |
| * | On January 13, at 13:23 (JST) there was a M8.2 earthquake off-shore east of the Chishima Islands (maximum seismic intensity 3 in Japan). The focal mechanism showed a normal fault with a tension axis in a NNW-SSE direction. It is thought that this event occurred within the Pacific plate. According to the GPS data, there were no remarkable changes observed in Japan before and after this event. |
| * | On January 25, there was a M6.1 earthquake near Taiwan. The focal mechanism showed a strike-slip fault with a compression axis in a WNW-ESE direction. to supplementary reports |
| * | On February 4, there was a M4.3 earthquake at a depth of approximately 65km under northwestern Chiba prefecture. |
[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
February 14, 2007
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during January 2007.
| M4.0 or greater: 140 (136 events occurred in December) | |
| M5.0 or greater: 27 (29 events occurred in December) | |
| M6.0 or greater: 4 (3 events occurred in December) |
Of the events listed above, 71 earthquakes of M4.0 or greater, 17 earthquakes of M5.0 or greater, and 1 earthquake of M6.0 or greater, were associated with the aftershock activity of the earthquakes off-shore east of the Chishima Islands on November 15 and on January 13. (In December, 53 earthquakes of M4.0 or greater, 18 earthquakes of M5.0 or greater, and 1 earthquake 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 January 2006 to the end of December 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.
There is no supplementary information for the Tohoku 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 January 29 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, January 29, 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. 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."
to the text
There is no supplementary information for the Kinki - Chugoku - Shikoku region.
- On January 16, there was a M4.7 earthquake at a depth of approximately 35km under the ocean near Amami Oshima.
"On January 13, at 13:23 (JST) there was a M8.2 earthquake off-shore east of the Chishima Islands (maximum seismic intensity 3 in Japan). The focal mechanism showed a normal fault with a tension axis in a NNW-SSE direction. It is thought that this event occurred within the Pacific plate. According to the GPS data, there were no remarkable changes observed in Japan before and after this event.":
Associated with this earthquake, tsunamis traveled to the coast of the
Okhotsk Sea and the whole Pacific coast (of Japan). The largest tsunami
observed in Japan had a height of 43cm (preliminary value at the Tsubota
tidal observatory on Miyakejima). (The largest tsunami associated with
the earthquake on November 15, 2006 had a height of 84cm at the Tsubota
tidal observatory on Miyakejima).
After the M7.9 event occurred on November 15, 2006 to the WNW of the recent earthquake, the seismic activity increased with its area divided into two parts; the western area of the M7.9 event and the eastern area immediately under the trench axis. The seismicity in both areas had been subsiding, when the recent event occurred. Earthquakes which occurred in the western area had focal mechanisms of reverse faults, which indicated those events occurred at the plate boundary, and earthquakes occurring in the eastern area had normal faults, showing that those events occurred within the Pacific plate.
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. |