Seismic Activity in Japan July 1999

1 Major Seismic Activity

* There was no marked activity.

• The whole of Japan M4 (July 1999)

2 Seismic Activity in each Region

(1) Hokkaido Region

* There was no marked activity.

• Hokkaido Region

(2) Tohoku Region

* There was no marked activity.

• Tohoku Region

(3) Kanto-Chubu Region

* A magnitude (M) 6.1 earthquake occurred on 3 July in the sea near Chichijima Island at a depth of about 440km. The focal mechanism showed a vertical compressional axis.

* An M4.9 earthquake occurred on 15 July near the border of Ibaraki Prefecture (Pref.) and Chiba Pref. at a depth of about 55km.

* An M5.1 earthquake occurred on 20 July in the sea near Chichijima Island.

* The results of GPS observation in the Tokai (Shizuoka-Aichi-Gifu) area showed no marked variation.

• Kanto-Chubu Region
• Seismic activity in the vicinity of the border between Ibaraki and Chiba Prefs.
• Seismic activity in the sea near Chichijima Island
• GPS continuous observation base-line chart (the vicinity of Kakegawa and Omaezaki)
• Base-line-length variation graph
• Height-difference variation graph

(4) Kinki-Chugoku-Shikoku Region

* An M4.4 earthquake occurred on 16 July in southeastern Hiroshima Pref. at a depth of about 20km, and caused damage.

• Kinki-Chugoku-Shikoku Region
• Seismic activity in southeastern Hiroshima Pref.

(5) Kyushu-Okinawa Region

* An M4.0 earthquake occurred on 31 July offshore of western Kagoshima Pref. at a depth of about 10km.

• Kyushu Region
• Seismic activity offshore of western Kagoshima Pref.
• Okinawa Region