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April 11, 2007 |
| On March 25, there was a M6.9 earthquake# at a depth of approximately 10km near the west coast of the Noto Peninsula.
This event had maximum seismic intensity 6 Upper in Ishikawa prefecture,
and caused damage with one death and about 300 injured people. The aftershock
activity associated with this earthquake included a M5.3 event on March
25 (maximum seismic intensity 5 Lower), a M4.8 event on March 26 (maximum
seismic intensity 5 Lower), and a M4.9 event on March 28 (maximum seismic
intensity 5 Lower). #Japan Meteorological Agency named this earthquake the Noto Hanto Earthquake in 2007. to supplementary reports |
| * | On March 30, there was a M5.6 earthquake at a depth of approximately 100km near Kunashiri Island. The focal mechanism had a compression axis in a WNW-ESE direction. This event occurred within the Pacific plate. | |
| * | On March 11, there was a M5.6 earthquake at a depth of approximately 15km off-shore east of Hokkaido. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. This event occurred within the aftershock area of the 1994 Off-shore East Hokkaido Earthquake. | |
| * | On March 18, there was a M5.6 earthquake at a depth of approximately 60km 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 Pacific and the continental plates and within the aftershock area of the 2003 Off-shore Tokachi Earthquake. | |
| * | On March 30, there was a M4.7 earthquake at a depth of approximately 45km under southern Tokachi subprefecture. The focal mechanism had a compression axis in a NW-SE direction. This event occurred at the boundary between the Pacific and the continental plates. to supplementary reports | |
| * | On March 31, there was a M4.8 earthquake at a depth of approximately 75km off-shore of Miyagi prefecture [under northern Miyagi prefecture]. The focal mechanism showed a reverse fault with a compression axis in the direction of the subducting Pacific plate. This event occurred within the Pacific plate and within the aftershock area of the earthquake (M7.1) off-shore of Miyagi prefecture on May 26, 2003. |
| * | On March 7, there was a M4.2 earthquake at a depth of approximately 15km onshore in northern Akita prefecture. to supplementary reports |
| * | On March 22, there was a M4.2 earthquake at a depth of approximately 80km near the border between Saitama and Chiba prefectures [under southern Saitama prefecture] | |
| * | On March 10, there was a M4.0 earthquake at a 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 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. | |
| * | (The Noto Hanto Earthquake in 2007 and its aftershock activity are described in a separate section.) | |
| * | 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 March 22, there was a M4.0 earthquake, and on March 23, there was a M4.1 earthquake at a depth of approximately 5km in the Kumamoto region, Kumamoto prefecture. to supplementary reports |
| * | 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 April 5, there was a M4.5 earthquake at a depth of approximately 10km under Sendai Bay [off-shore of Miyagi prefecture]. The focal mechanism showed a reverse fault with a compression axis in an ENE-WSW direction. This event occurred within the crust. |
| * | On April 10, there was a M4.3 earthquake at a depth of approximately 75km off-shore of Miyagi prefecture [on southern coast of Iwate prefecture]. |
[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
April 11, 2007
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during March 2007.
| M4.0 or greater: 125 (67 events occurred in February) | |
| M5.0 or greater: 16 (10 events occurred in February) | |
| M6.0 or greater: 3 (1 event occurred in February) |
Of the events listed above, 30 earthquakes of M4.0 or greater and 3 earthquakes of M5.0 or greater were associated with the aftershock activity of the Noto Hanto Earthquake in 2007.
(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 March 2006 to the end of February 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 |
- Since late March, light seismic activity has been observed off-shore southeast of Etorofu Island, with the largest earthquake a M5.5 event (on April 2).
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 March 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, March 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."
to the text
There is no supplementary information for the Kinki - Chugoku - Shikoku region.
"On March 22, there was a M4.0 earthquake, and on March 23, there
was a M4.1 earthquake at a depth of approximately 5km in the Kumamoto region,
Kumamoto prefecture.":
Including these earthquakes, there was slightly active seismicity for three days.
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. |