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July 11, 2007 |
| * | There was no remarkable activity. to supplementary reports |
| * | On June 23, there was a M4.9 earthquake at a depth of approximately 130km under western Hidaka subprefecture. The focal mechanism had a tension axis in a N-S direction. This earthquake occurred within the Pacific plate. to supplementary reports | |
| * | There was no remarkable activity. to supplementary reports |
| * | On June 23, there was a M4.2 earthquake at a depth of approximately 55km off-shore of Ibaraki prefecture. | |
| * | On June 2, there was a M4.6 earthquake at a depth of approximately 50km under southern Ibaraki prefecture. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. This event occurred at the boundary between the Philippine Sea and the continental plates. | |
| * | On June 1, there was a M4.5 earthquake at a depth of approximately 60km under northern Saitama prefecture. The focal mechanism showed a strike-slip fault with a compression axis in a NNW-SSE direction. This event occurred within the Philippine Sea plate. | |
| * | On June 28, there was a M4.1 earthquake at a depth of approximately 15km in western Tama, Tokyo. The focal mechanism showed a reverse fault with a compression axis in a NE-SW direction. This event occurred within the crust. | |
| * | On June 1, there was a M4.3 earthquake at a depth of approximately 15km in western Shizuoka prefecture. The focal mechanism showed a strike-slip fault with a compression axis in a WNW-ESE direction. This event occurred within the crust. | |
| * | The aftershock activity of the Noto Hanto Earthquake on March 25 (Noto Hanto Earthquake in 2007) has been declining overall, although there was a M5.0 event near the main shock on June 11. | |
| * | On June 22, there was a M4.6 earthquake at a depth of approximately 10km off-shore west of Ishikawa prefecture. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. This event occurred within the crust, at a location to the south of the aftershock area of the Noto Hanto 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 | |
| * | On June 6, there was a sequence of seismicity with the largest event a M4.9 earthquake in central Oita prefecture. The focal mechanism of the largest earthquake (M4.9) showed a normal fault with a strike-slip component, which had a tension axis in a N-S direction. This event occurred within the crust. The seismic activity was strong at first and has been declining at present. to supplementary reports | |
| * | On July 1, there was a M5.8 earthquake at a depth of approximately 130km under northern Nemuro subprefecture. The focal mechanism had a tension axis in the direction of the subducting Pacific plate. This event occurred within the Pacific plate. | |
| * | On July 3, there was a M4.5 earthquake at a depth of approximately 50km under the border between Ibaraki and Chiba prefectures [southern Ibaraki prefecture]. The focal mechanism showed a reverse fault with a compression axis in an E-W direction. This event occurred at the boundary between the Pacific and the Philippine Sea plates. | |
[ ] were the regional names of the epicenters used in the Japan Meteorological Agency announcement.
July 11, 2007
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during June 2007.
| M4.0 or greater: 81 (81 events occurred in May) | |
| M5.0 or greater: 11 (11 events occurred in May) | |
| M6.0 or greater: 0 (There has been a total of 7 events for 2007 by the end of June.) |
(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 June 2006 to the end of May 2007.
| - 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 | |
| - 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 |
There is no supplementary information for the Hokkaido region.
There is no supplementary information for the Tohoku region.
"On June 28, there was a M4.1 earthquake at a depth of approximately 15km
in western Tama, Tokyo. The focal mechanism showed a reverse fault with
a compression axis in a NE-SW direction. This event occurred within the
crust.":
In the area near this event, there was light seismic activity during the period from May 6 through 12, with the largest earthquake a M3.8 event on May 9.
"The aftershock activity of the Noto Hanto Earthquake on March 25 (Noto
Hanto Earthquake in 2007) has been declining overall, although there was
a M5.0 event near the main shock on June 11.":
According to leveling results, a maximum uplift of approximately 40cm was
observed in the area from Shika-machi through Wajima-city. That is consistent
with the geological field surveys and the analysis results of the SAR interferometry.
"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 June 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, June 25, 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, from June 15 to 17, some low-frequency earthquakes and crustal movements were observed, apparently associated with the short-term slow slip at the plate boundary directly under southern Nagano prefecture. In this vicinity, a similar phenomenon was seen from late August until early September last year."
There is no supplementary information for the Kinki - Chugoku - Shikoku region.
"On June 6, there was a sequence of seismicity with the largest event a
M4.9 earthquake in central Oita prefecture. The focal mechanism of the
largest earthquake (M4.9) showed a normal fault with a strike-slip component
and had a tension axis in a N-S direction. This event occurred within the
crust. The seismic activity was strong at first, and has been declining
at present.":
In the vicinity of the recent event, there was a sequence of seismicity
in April, 2000, with the largest earthquake a M4.2 event, and other similar
activity has occurred frequently. In addition, the Beppu - Haneyama Fault
Zone is located in this vicinity.
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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 |
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| 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 |