February 8, 2013
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
* On January 28, there was a M4.8 earthquake in northern Ibaraki prefecture. This event had a maximum seismic intensity 5 Lower in Ibaraki prefecture.
* On January 31, there was a M4.7 earthquake in northern Ibaraki prefecture. This event had a maximum seismic intensity 5 Lower in Ibaraki prefecture.
* On January 3, there was a M4.8 earthquake at a depth of approximately 25 km in the central northern Rumoi region. The focal mechanism showed a reverse fault with a compression axis in an E-W direction. This event occurred within the crust.
* On January 24, there was a M5.2 earthquake at a depth of approximately 65 km, offshore southeast of Nemuro Peninsula. The focal mechanism had a tension axis in a direction of the subducting Pacific plate. This event occurred within the Pacific plate.
* On January 8, there was a M5.4 earthquake at a depth of approximately 35 km, offshore Iwate prefecture. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred on the boundary between the Pacific and the continental plates.
* On January 10, there was a M5.0 earthquake at a depth of approximately 50 km, offshore Fukushima prefecture. The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred on the boundary between the Pacific and the continental plates.
* On January 13, there was a M4.8 earthquake at a depth of approximately 50 km, offshore Iwate prefecture. The focal mechanism showed a reverse fault with a compression axis in an NNW-SSE direction. This event occurred within the Pacific plate.
* On January 22, there was a M5.1 earthquake at a depth of approximately 15 km, offshore east of Chiba prefecture [offshore Ibaraki prefecture]. The focal mechanism showed a normal fault with a tension axis in a WNW-ESE direction. This event occurred within the crust of the continental plate.
* On January 28, there was a M4.8 earthquake at a depth of approximately 75 km under northern Ibaraki prefecture. The focal mechanism showed a normal fault with a tension axis in an ENE-WSW direction. This event occurred within the Pacific plate.
* On January 31, there was a M4.7 earthquake at a depth of approximately 10 km in northern Ibaraki prefecture. The focal mechanism showed a normal fault with a tension axis in an NE-SW direction. This event occurred within the crust.
* In the GNSS data for the Tokai region, there have been no changes of activity which are likely to be associated with the Tokai earthquake.
There was no remarkable activity.
* On January 7, there was a M5.4 earthquake at a depth of approximately 70 km under the ocean near Yonagunijima. This event occurred within the subducting Philippine Sea plate.
* On January 28, there was a M4.9 earthquake at a depth of approximately 50 km under the ocean near Okinawa Main Island. The focal mechanism showed a reverse fault with a compression axis in an NW-SE direction. This event occurred on the boundary between the Philippine Sea and the continental plates.
* On February 2, there was a 6.5 earthquake at a depth of approximately 110 km under the southern Tokachi region [central Tokachi region]. The focal mechanism had a tension axis in a direction of the subsiding Pacific plate. This event occurred within the Pacific plate.
Note: -[ ] was the regional name of the epicenter used in the Japan Meteorological Agency announcement.
GNSS (Global Navigation Satellite System)
is a general name of satellite positioning system such as GPS.
February 8, 2013
Earthquake Research Committee
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during January 2013.
(reference)
The following events for the period from January 2012 to late December 2012 have been listed as "Major Seismic Activities" in monthly "Evaluation of Seismic Activities"
| |
– Offshore Fukushima Prefecture | M5.1 on January 23, 2012 (Depth of approximately 50 km) |
| – Eastern Yamanashi Prefecture-Fujigoko | M5.4 on January 28, 2012 (Depth of approximately 20 km) | |
| |
– Near Sado | M5.7 on February 8, 2012 (Depth of approximately 15 km) |
| – Northern Ibaraki Prefecture | M5.2 on February 19, 2012 (Depth of approximately 5 km) |
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| – Offshore Ibaraki Prefecture | M5.3 on March 1, 2012 (Depth of approximately 55 km) |
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| – Northern Ibaraki Prefecture | M5.4 on March 10, 2012 (Depth of approximately 5 km) |
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| – Offshore Sanriku | M6.9 on March 14, 2012 | |
| – Offshore East of Chiba Prefecture | M6.1 on March 14, 2012 (Depth of approximately 15 km) |
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| – Offshore Iwate Prefecture | M6.6 on March 27, 2012 (Depth of approximately 20 km) |
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| – Offshore Fukushima Prefecture | M5.9 on April 1, 2012 (Depth of approximately 55 km) |
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| – Northeastern Chiba Prefecture | M5.8 on April 29, 2012 (Depth of approximately 50 km) |
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| – Offshore East of Aomori Prefecture | M6.1 on May 24, 2012 (Depth of approximately 60 km) |
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| – Northern Nagano Prefecture | M5.2 on July 10, 2012 (Depth of approximately 10 km) |
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| – Southern Tokachi Region | M6.1 on August 25, 2012 (Depth of approximately 50 km) |
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| – Offshore Miyagi Prefecture | M5.6 on August 30, 2012 (Depth of approximately 60 km) |
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| – Offshore Miyagi Prefecture | M5.6 on October 25, 2012 (Depth of approximately 50 km) |
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| – Offshore Sanriku | M7.3 on December 7, 2012 |
There is no supplementary information for the Hokkaido region.
There is no supplementary information for the Tohoku region.
– In the aftershock area of the 2011 off the Pacific Coast of Tohoku Earthquake, brisk seismicity has been seen. There is fear that large aftershocks will occur from now on, and there is a possibility that it will be hit by strong shaking and high tsunami. Crustal movements to the east which are thought to be the postseismic deformation have still been observed in a wide area from the Tohoku through the Kanto-Chubu regions, but they have gradually been decaying.
"In the GNSS data for the Tokai region, there have been no changes
of activity which are likely to be associated with the Tokai earthquake":
(This evaluation is in agreement with the views presented at the regular meeting on January 21 of the Assessment Committee for Areas under Intensified Measures against Earthquake Disaster (reference below).)
(Reference)
Recent seismic and crustal activity in the Tokai region and its vicinity (Seismological and Volcanological Department, Japan Meteorological Agency, January 21)
"No changes of activity which are likely to be associated with the Tokai earthquake have been observed until now. (Excerpted)"
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: