4 (1 to 30 Nov, 1998)
| 9 December 1998 |
| Headquarters for Earthquake Research Promotion |
| Earthquake Research Committee |
Seismic Activity in Japan November 1998
A magnitude (M)6.3 earthquake occurred on 20 November south of the island Ishigakijima.
* There was no unusual activity.
An M5.1 earthquake occurred on 24 November offshore of Miyagi Prefecture (Pref.) at a depth of 80km. This earthquake occurred on the bottom plane of the double-planed deep seismic zone of the subducting Pacific Plate; the focal mechanism has its tension axis in the direction of plate subduction.
* An M4.6 earthquake occurred on 8 November in Northwest Chiba Pref. at a depth of 80km. The focal mechanism of this earthquake was of the reverse-fault type with a compressional axis in an east-west direction.
* An M4.7 earthquake occurred on 16 November off the coast of Noto Peninsula (Ishikawa Pref.) at a depth of 15km. This earthquake occurred in the aftershock zone of the M6.6 earthquake that occurred on 7 February 1993.
* An M4.3 earthquake occurred on 28 November in Northwest Chiba refecture at a depth of 70 km. Its hypocenter was in roughly the same position as the hypocenter of the M5.1 earthquake that occurred on 29 August.
* Seismic activity on the borders between Nagano, Gifu, and Toyama prefs. continues in the area centering on Kamikochi, but the number of earthquakes is diminishing.
* Results of GPS observation of the Shizuoka-Aichi-Gifu area showed no notable variation.
* An M4.2 earthquake occurred on 10 November in western Kochi Pref. at a depth of 45km.
* An M4.5 earthquake occurred in the coastal waters of the island Amami Oshima at a depth of 20km.
* An M6.3 earthquake occurred on 20 November south of the island Ishigakijima. This earthquake occurred in a position to the northeast of and contiguous to the aftershock zone of the M7.6 earthquake that occurred on 4 May 1998.
* An M4.7 earthquake occurred on 7 December in the coastal waters of Amami Oshima at a depth of 60km.
