|
March 14, 2007 |
| There was no remarkable activity. to supplementary reports |
| * | On February 17, there was a M6.2 earthquake at a depth of approximately 40km off-shore of Tokachi. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred at the boundary between the continental and the Pacific plates. This event occurred within the aftershock region of the 2003 Off-shore Tokachi Earthquake. Its largest aftershock (M7.1, maximum seismic intensity 6 Lower) occurred in the vicinity of the recent event. to supplementary reports | |
| * | There was no remarkable activity. to supplementary reports |
| * | On February 4, there was a M4.3 earthquake at a depth of approximately 65km under northwestern Chiba prefecture. | |
| * | 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 March 7, there was a M4.2 earthquake at a depth of approximately 15km onshore in northern Akita prefecture. |
| * | On March 8, there was a M6.0 earthquake at a depth of approximately 150km under the ocean near Torishima. The focal mechanism had a tension axis in an ENE-WSW direction. This event occurred within the Pacific plate. |
| * | On March 9, there was a deep M6.2 earthquake at a depth of approximately 500km under the northern Japan Sea. The focal mechanism had a compression axis in the direction of the subducting Pacific plate. This event occurred within the Pacific plate. |
| * | On March 10, there was a M4.0 earthquake at depth of approximately 10km in the Chuetsu region, Niigata prefecture. This event occurred approximately 20km southwest of the aftershock region of the 2004 Niigata Chuetsu Earthquake. |
| * | On March 11, there was a M5.6 earthquake at a depth of approximately 15km off-shore east of Hokkaido. The focal mechanism (Harvard University) showed a reverse fault with a compression axis in a NW-SE direction. This event occurred within the aftershock region of the 1994 Off-shore East Hokkaido Earthquake. |
[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
March 14, 2007
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during February 2007.
| M4.0 or greater: 67 (140 events occurred in January) | |
| M5.0 or greater: 10 (27 events occurred in January) | |
| M6.0 or greater: 1 (4 events occurred in January) |
(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 February 2006 to the end of January 2007.
| - 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 | |
| - Off-shore east of the Chishima Islands | M8.2 on January 13, 2007 |
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 February 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, February 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. 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.
In addition, during the period from February 5 to 10, some crustal movements and low-frequency earthquakes apparently associated with the short-term slow slip at the plate boundary, were observed in Aichi prefecture. In this vicinity, similar phenomena were seen in August and September last year."
to the text
There is no supplementary information for the Kinki - Chugoku - Shikoku region.
There is no supplementary information for the Kyushu - Okinawa region.
- Aftershock activity associated with the M7.9 and M8.2 earthquakes that occurred off-shore east of the Chishima Islands on November 15, 2006 and January 13, 2007, has been declining.
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. |
|
| 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. |