4 (May 1999)
| 7 June 1999 |
| Headquarters for Earthquake Research Promotion |
| Earthquake Research Committee |
Seismic Activity in Japan May 1999
* A magnitude (M) 6.4 intermidiate-depth earthquake occurred on 13 May in south-central Kushiro Administrative District, and caused damage.
* An M6.4 earthquake occurred on 13 May in south-central Kushiro Administrative District at a depth of about 100km, and caused damage. The focal mechanism showed a tension axis in the direction of plate subduction. This earthquake occurred within the subducting Pacific plate, and was adjacent to northwest part of the aftershock zone of the 1993 earthquake (M7.8) offshore of Kushiro.
* An M4.6 earthquake occurred on 31 May in south-central Kushiro Administrative District at a depth of about 70km. This earthquake occurred on the upper plane of the double-planed deep seismic zone associated with subducting Pacific Plate.
* An M3.6 earthquake occurred on 22 May in the northwestern Iwate Prefecture (Pref.) at a depth of less than 5km. The hypocenter of this earthquake was in the vicinity of Mt. Iwatesan, northeast of the M6.1 earthquake of 3 September 1998.
* An M4.7 earthquake occurred on 7 May in central Shizuoka Pref. at a depth of about 20km. The focal mechanism was a strike-slip type showing a NW-SE compressional axis. From the depth of the hypocenter and the focal mechanism, it is thought to have occurred above the plate boundary.
* An M4.1 earthquake occurred on 22 May in western Kanagawa Pref. at a depth of about 25km.
* The seismic activity in central Mie Pref. that commenced in late January has diminished somewhat but continues.
* The results of GPS observation in the Tokai (Shizuoka-Aichi-Gifu) area showed no marked variation.
* There was no marked activity.
* There was no marked activity.
