2013 April 13th Earthquake in Awaji Island area

Launched:April 15th, 2013

Last updated:April 16th,2013


An earthquake with magnitude 6.3 occurred at Awaji Island area (located in southwest Japan) on 13th April, 05:33 JST.

[Note: Research/analysis outcomes gained by individual researchers in our institute will be posted on this website. All information publicized here do not indicate any official opinion as the Earthquake Research Institute.]

[Basic Information](JMA)

  • Location of hypocenter: Latitude 34.4N, Longitude 134.8E,
  •  10km depth
  • Magnitude: 6.3

Temporary Observation of the aftershocks

In order to clarify the earthquake plain fault, aftershock distribution and focal mechanism solution, we launched a temporary aftershock observation together with DPRI, Kyushu University and Kochi University.

(Associate prof. Shinichi Sakai)

Fig.1 Temporary observation sites and aftershocks (top)and cross-sectional diagram of its depth
(bottom left: east-west, bottom right: north-south)
Red star: main shock, White circle: aftershocks, ■:Temporary off-line observation sites(DPRI), ▲:Telemeter observation sites(Tsuna:JMA), ■ : Temporary telemeter observation sites (Eisaki:Kyushu.Univ.), ■: Temporary telemeter observation sites(Goshiki:ERI), ■: Temporary off-line observation sites (Kochi.Univ).
Aftershocks distributes around 10 to 15km depth, in direction of NNW-SSE, on a plain of high-angle westerly dip.
This distribution corresponds to one of the earthquake fault surface expected from the focal mechanism solution.


Fig.2 The hypocenter (right) and aftershock distribution after the earthquake in the southern Hyogo pref. (left)
This time, the earthquake occurred at the southern edge of the aftershock distribution derived by the joint-observation of the aftershocks of Southern Hyogo earthquake (27th January to 9th April).
It is located slightly on the South East, and not in the line of the fault plain of the earthquake of southern Hyogo.



Moment Tensor Solution derived by W-phase Source Inversion

Following is the Moment Tensor Solution derived by W-phase Source Inversion using waveform data recorded in regional scale. This method is developed by Kanamori and Rivera (2008).

(Associate prof.Hiroshi Tsuruoka)

Waveform recorded in the Earthquake Data Sharing system

In the Center for Geophysical Observation and Instrumentation, ERI, we provide earthquake data observed in the Kanto and Koshinetsu area, Kii peninsula and surrounding area and the western Seto Inland sea as a regional center of observational research for earthquake prediction.

(Center for Geophysical Observation and Instrumentation)