February 8, 2010
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
There was no remarkable activity.
* On January 15, there was a M5.0 earthquake at a depth of approximately 50km under southern Tokachi subprefecture. The focal mechanism showed a reverse fault with a compression axis in a NW-SE direction. This event occurred at the boundary between the Pacific and the continental plates.
* On January 16, there was a M5.1 earthquake off-shore east of Hokkaido. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction.
* On January 24, there was a M4.5 earthquake at a depth of approximately 15km, off-shore east of Aomori prefecture.
* On January 30, there was a M4.0 earthquake at a depth of approximately 15km in northern Miyagi prefecture. The focal mechanism showed a reverse fault with a compression axis in an E-W direction. This event occurred within the crust.
* On January 30, there was a M4.1 earthquake at a depth of approximately 10km in southern Miyagi prefecture. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred within the crust.
* On January 21, there was a M4.4 earthquake in the Izu region, Shizuoka prefecture [off-shore east of the Izu Peninsula]. The focal mechanism had a compression axis in a NNW-SSE direction.
* There have been no anomalous changes observed in the GPS data for the Tokai region.
There was no remarkable activity.
* On January 7, there was a M4.8 earthquake under the ocean area near Amami Oshima.
* On January 25, there was a M5.4 earthquake at a depth of approximately 50km, off-shore east of the Osumi Peninsula. The focal mechanism had a tension axis in the direction of the subducting Philippine Sea plate. It is thought that this event occurred within the Philippine Sea plate.
* On January 15, there was a M5.6 earthquake at a depth of approximately 120km, off-shore northwest of the Okinawa Main Island. This event occurred within the Philippine Sea plate. The focal mechanism had a compression axis in a NNW-SSE direction.
[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
February 8, 2010
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during January 2010.
(reference)
The following regions have been noted as having major seismic activity during the period from January 2009 to the end of December 2009.
| – 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 |
There is no supplementary information for the Hokkaido region.
There is no supplementary information for the Tohoku region.
"On January 21, there was a M4.4 earthquake in the Izu region, Shizuoka
prefecture [off-shore east of the Izu Peninsula]. (excerpted)"
There was a strong seismicity off-shore east of the Izu Peninsula in December ,2009. The recent earthquake occurred near the northwestern edge of that active region. There were no remarkable changes in seismicity or crustal movements before and after the event.
"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 January 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, January 25, 2010)
"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
Within the crust under mid-western Shizuoka prefecture, general seismicity has been slightly strong since mid-2005.
There continue to be fewer events within the Philippine Sea plate under the region around Hamana lake.
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."
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: