June 11, 2009
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
There was no remarkable activity. to supplementary reports
There was no remarkable activity. to supplementary reports
There was no remarkable activity. to supplementary reports
* On May 12, there was a M4.8 earthquake at a depth of approximately 10km in the Joetsu region, Niigata prefecture. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. This event occurred within the crust.
* On May 25, there was a M4.7 earthquake at a depth of approximately 25km in western Shizuoka prefecture. The focal mechanism showed a strike-slip fault with a tension axis in an E-W direction. This event occurred within the Philippine Sea plate.
* 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 June 5, there was a M6.4 earthquake at a depth of approximately 30km, 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. Associated with this event, small crustal movements were observed in the Hidaka and the southern Tokachi regions.
* On June 6, there was a M5.9 earthquake off-shore east of Chiba prefecture.
June 11, 2009
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during May 2009.
(reference)
The following regions have been noted as having major seismic activity during the period from May 2008 to the end of April 2009.
| - Off-shore of Ibaraki prefecture | M7.0 on May 8, 2008 | |
| - Iwate-Miyagi Nairiku Earthquake in 2008 | M7.2 on June 14, 2008 (depth approximately 10km) | |
| - Off-shore of Ibaraki prefecture | M5.2 on July 5, 2008 (depth approximately 50km) | |
| - Near Okinoerabujima | M6.1 on July 8, 2008 (depth approximately 45km) | |
| - Off-shore of Fukushima prefecture | M6.9 on July 19, 2008 | |
| - Central Iwate prefecture | M6.8 on July 24, 2008 (depth approximately 110km) | |
| - Off-shore of Tokachi | M7.1 on September 11, 2008 |
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 May 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" (Seismological and Volcanological Department, Japan Meteorological Agency, May 25, 2009)
"So far, there have been no changes of activity which are likely to be associated with the so-called Tokai earthquake.
1. Status of seismicity
There was no remarkable seismic activity in general.
There are continued less frequent occurrences of events equal to or larger than M3.5 within the Philippine Sea plate under mid-western Shizuoka prefecture. Also, there continue to be fewer events within the Philippine Sea plate under the region around Hamana lake. On the other hand, seismicity has been continuing to be slightly strong within the crust in mid-western Shizuoka prefecture. In other regions, seismic activity is generally at a normal level.
In addition, during the period from May 4 through 13, there were deep low-frequency earthquakes observed in the area from Mie prefecture, which is adjacent to the Tokai region, through Nara prefecture. In this vicinity, deep low-frequency earthquakes were also observed in November last year. Other deep low-frequency earthquakes were observed near the plate boundary under western Aichi prefecture on May 17.
2. Status of crustal movements
There were no notable changes observed in general.
According to the GPS data and leveling results, the trend of long-term subsidence at Omaezaki has been continuing as before."
There is no supplementary information for the Kinki-Chugoku-Shikoku region.
There is no supplementary information for the Kyushu-Okinawa region.
Reference 1
Earthquakes that are described in the "Evaluation of Seismic Activity" (Monthly Report of Seismic Activity in Japan) have the following features.
Reference 2
Information that is described in the "Supplementary Information to the Evaluation" includes: