February 9, 2017
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion
There was no remarkable activity.
There was no remarkable activity.
* On January 5, there was a M5.3 earthquake at a depth of approximately 55 km, offshore Fukushima prefecture. The focal mechanism showed a reverse fault type with a compression axis in an NW-SE direction.
* On January 5, there was a M5.6 earthquake offshore Fukushima prefecture. The focal mechanism showed a normal fault type with a tension axis in a WNW-ESE direction. This event occurred in the activity area of a M7.4 earthquake, which occurred on November 22, 2016 offshore Fukushima prefecture, in the continental crust.
* On January 26, there was a M5.2 earthquake at a depth of approximately 35 km, offshore Iwate prefecture. The focal mechanism showed a reverse fault type with a compression axis in an E-W direction. This event occurred at the boundary between the Pacific and the continental plates.
* On January 28, there was a M5.0 earthquake at a depth of approximately 150 km under the southern inland, Akita prefecture. The focal mechanism had a tension axis in an ENE-WSW direction. This event occurred within the Pacific plate.
* On January 13, there was a M4.9 earthquake at a depth of approximately 50 km under the northeastern Chiba prefecture. The focal mechanism showed a reverse fault type with a compression axis in an E-W direction. This event occurred at the boundary between the Pacific and the Philippine Sea plates.
* On January 18, there was a M4.2 earthquake at a depth of approximately 55 km, offshore Ibaraki prefecture. The focal mechanism showed a reverse fault type with a compression axis in a WNW-ESE direction. This event occurred at the boundary between the Pacific and the continental plates.
* In the GNSS data for the Tokai region, there has been no change of activity which is likely to be associated with the Tokai earthquake.
There was no remarkable activity.
* On January 11, there was a M3.4 earthquake at a depth of approximately 10 km in the Kumamoto region, Kumamoto prefecture. The focal mechanism showed a normal fault type with a tension axis in an NNW-SSE direction. This event occurred within the crust.
Note: GNSS (Global Navigation Satellite System) is a general name of satellite positioning system such as GPS.
February 9, 2017
Earthquake Research Committee
The following are the numbers of earthquakes by magnitude (M) that occurred in Japan and the surrounding area during January 2017.
(reference)
The following events for the period from January 2016 to late December 2016 have been listed as "Major Seismic Activities" in monthly "Evaluation of Seismic Activities."
| – Sanpachi-Kamikita Region, Aomori Prefecture | M4.6 on January 11, 2016 (Depth of approximately 10 km) |
|
| – Offshore Urakawa | M6.7 on January 14, 2016 (Depth of approximately 50 km) |
|
| – Kumamoto Earthquakes | M6.5 on April 14, 2016 and M7.3 on April 16, 2016 (Depth of approximately 10 km) |
|
| – Southern Ibaraki Prefecture | M5.5 on May 16, 2016 (Depth of approximately 40 km) |
|
| – Uchiura Bay | M5.3 on June 16, 2016 (Depth of approximately 10 km) |
|
| – Northern Ibaraki Prefecture | M5.4 on July 27, 2016 (Depth of approximately 55 km) |
|
| – Kumamoto Region, Kumamoto Prefecture | M5.2 on August 31, 2016 (Depth of approximately 15 km) |
|
| – Ocean Area near Okinawa Main Island | M5.6 on September 26 (Depth of approximately 45 km) |
|
| – Central Tottori Prefecture | M6.6 on October 21, 2016 (Depth of approximately 10 km) |
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| – Offshore Fukushima Prefecture | M7.4 on November 22, 2016 (Depth of approximately 10 km) |
|
| – Northern Ibaraki Prefecture | M6.3 on December 28, 2016 (Depth of approximately 10 km) |
There is no supplementary information for Hokkaido region.
There is no supplementary information for Tohoku region.
– In the northern Ibaraki prefecture, where a M6.3 earthquake occurred on December 28, 2016, 13 earthquakes with seismic intensity 1 or over occurred in January. Of these the maximum was the M3.7 one on January 1. The seismic activity still continues, decaying as a whole.
–"In the GNSS data for the Tokai region, there has been no change
of activity which is likely to be associated with the Tokai earthquake.":
(This evaluation is in agreement with the views presented at the regular
meeting on January 30 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 30, 2017)
"No change of activity which is likely to be associated with the Tokai earthquake has been observed until now. (Excerpted)"
There is no supplementary information for Kinki-Chugoku-Shikoku region.
– "On January 11, there was a M3.4 earthquake at a depth of
approximately 10 km in the Kumamoto region, Kumamoto prefecture. (Excerpted)
"
In January, 1 earthquake with maximum seismic intensity 4 (0 in December, 2016) and 1 earthquake with maximum seismic intensity 3 (3 in December, 2016) occurred in the Kumamoto and Aso regions, Kumamoto prefecture. A series of seismic activity of the 2016 Kumamoto Earthquakes in the Kumamoto and Aso regions still continues, decaying as a whole. According to the GNSS observation, postseismic deformation is still observed in the area centered on the series of the seismic activity.
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: