September 9, 2010
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
There was no remarkable activity.
* On August 14, there was a M4.6 earthquake at a depth of approximately 110 km under western Hidaka region [mid-eastern Iburi region]. The focal mechanism had a compression axis in a NW-SE direction. This event occurred within the Pacific plate.
* On August 10, there was a M6.3 earthquake off-shore of Sanriku.
* On August 3, there was a M4.6 earthquake at a depth of approximately 80 km, under northern Ibaraki prefecture. The focal mechanism had a compression axis in the direction of the subducting Pacific plate. This event occurred within the Pacific plate.
* On August 14, there was a M5.2 earthquake at a depth of approximately 110 km, under the ocean area near Chichijima. The focal mechanism showed a reverse fault with a compression axis in a NE-SW direction. This event occurred within the Pacific plate.
* There have been no anomalous changes observed in the GPS data for the Tokai region.
There was no remarkable activity.
There was no remarkable activity.
* On September 1, there was a M5.0 earthquake at a depth of approximately 45km, off-shore of Miyagi prefecture. 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.
* On September 4, there was a M5.1 earthquake off-shore of Kushiro.
[ ] was the regional name of the epicenter used in the Japan Meteorological
Agency announcement.
September 9, 2010
Earthquake Research Committee
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during August 2010.
(reference)
The following events for the period from August 2009 to the end of July 2010 have been listed as "Major Seismic Activity" in monthly "Evaluation of Seismic Activity".
– Under Suruga Bay | M6.5 on August 11, 2009 (depth of approximately 25km) | |
– Off-shore East of Hachijojima | M6.6 on August 13, 2009 | |
– Under the Ocean Area near Ishigakijima | M6.7, M6.6 on August 17, 2009 | |
– Off-shore East of the Izu Peninsula | Seismic activity with M5.0 on December 17, M5.1 on December 18, 2009 |
|
– Under the Ocean Area near the Okinawa Main Island | M7.2 on February 27, 2010 | |
– Along the Central Coast of Chile | Mw8.8 on February 27, 2010 | |
|
– Off-shore of Fukushima Prefecture | M6.7 on March 14, 2010 |
|
– Off-shore of Fukushima Prefecture | M6.2 on June 13, 2010 |
|
– Northeastern Chiba Prefecture | M4.9 on July 23, 2010 |
There is no supplementary information for the Hokkaido region.
– Near the border between Iwate and Akita prefectures, there was slightly strong seismic activity with the largest M3.6 since around July 31. It has been subsiding.
"There have been no anomalous changes observed in the GPS data for
the Tokai region":
(This evaluation is in agreement with the views (reference below) presented
at the procedural meeting on August 31 of the Assessment Committee for
Areas under Intensified Measures against Earthquake Disaster.)
(Reference) Recent seismic and crustal activity in the Tokai region and its vicinity (Seismological and Volcanological Department, Japan Meteorological Agency, August 31, 2010)
"So far, there have been no changes of activity which are likely to be associated with the Tokai earthquake.
1. Status of seismicity
General seismicity has been slightly strong since mid-2005 within the crust under mid-western Shizuoka prefecture.
There continue to be fewer events within the Philippine Sea plate under the region around Hamanako. In other regions, seismic activity is generally at a normal level.
2. Status of crustal movements
There have been no remarkable changes observed over the entire region.
According to the GPS data and leveling results, the trend of long-term subsidence at Omaezaki has been continuing as before."
– Non-stationary crustal movements are still observed near Bungo Strait, which have been seen since around autumn 2009. It is thought that they have been caused by slow slip at the boundary between the Philippine Sea and the continental plates.
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: