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Report on Asamayama (Japan) — November 2003

Bulletin of the Global Volcanism Network, vol. 28, no. 11 (November 2003)
Managing Editor: Edward Venzke.

Asamayama (Japan) Volcanic tremor episodes in April 2003

Please cite this report as:

Global Volcanism Program, 2003. Report on Asamayama (Japan). In: Venzke, E. (ed.), Bulletin of the Global Volcanism Network, 28:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200311-283110.

Volcano Profile |  Complete Bulletin


Asamayama

Japan

36.406°N, 138.523°E; summit elev. 2568 m

All times are local (unless otherwise noted)


Asama has been seismically active since 18 September 2000. Heightened seismicity occurred in June 2002, when the daily number of volcanic earthquakes exceeded 300 (BGVN 27:06). The Asama Volcano Observatory (ERI, University of Tokyo) and Japan Meteorological Agency (JMA) reported a new episode of elevated seismicity during 18-19 September 2002 (BGVN 28:04). According to JMA there were brief ash eruptions on 6 February, 30 March, 7 April, and 18 April 2003 to heights of 200-300 m above the crater with minor ashfall around the summit (BGVN 28:04).

Seismic data and plume observations compiled from JMA reports for September 2000 through April 2003 (table 2) reflect this recent activity. White plumes were reported from the Kama-yama crater during every month in this period, with the addition of grayish white plumes on 6 February, 7 April, and 18 April. These white plumes only rose to 1 km or above in April and May 2001, and June and August 2002. In addition, short isolated episodes of volcanic tremor were recorded in October 2001, February 2003, and March 2003. However, 12 episodes occurred in April 2003, with five on the 29th.

Table 2. Summary of seismicity and plume observations at Asama, January 2000-April 2003. All reported plumes originated from the Kama-yama crater, and were described as either white (W) or grayish white (GW). Data courtesy of JMA.

Month Total volcanic earthquakes Maximum volcanic earthquakes (date) Plume Height (m) (date) Plume Color
Jan 2000 5 1 (4, 5, 9, 14, 18) 300 (25, 26, 28) W
Feb 2000 3 2 (26) 300 (10) W
Mar 2000 8 3 (29) 300 (1, 10) W
Apr 2000 75 27 (17) 400 (17) W
May 2000 10 2 (19, 27) 500 (5, 30) W
Jun 2000 26 6 (4) 300 (4, 5, 15) W
Jul 2000 13 3 (11, 29) 300 (9) W
Aug 2000 20 3 (5) 200 (2, 21, 26) W
Sep 2000 419 149 (19) 500 (21) W
Oct 2000 79 27 (31) 400 (19) W
Nov 2000 322 34 (25) 300 (4, 6, 23, 27) W
Dec 2000 234 18 (4, 6) 500 (27) W
Jan 2001 41 7 (2) 700 (30) W
Feb 2001 128 46 (19) 500 (15) W
Mar 2001 162 29 (24) 800 (12, 21, 24) W
Apr 2001 182 41 (10) 1000 (28) W
May 2001 20 3 (3, 36) 1200 (17) W
Jun 2001 11 2 (6, 7) 800 (3) W
Jul 2001 115 24 (13) 600 (5) W
Aug 2001 36 5 (18) 400 (13, 28, 29) W
Sep 2001 99 14 (23) 500 (24, 25) W
Oct 2001 113 12 (29) 700 (27) W
Nov 2001 144 13 (9) 600 (11) W
Dec 2001 80 7 (4) 200 (many) W
Jan 2002 150 11 (15) 300 (6, 24) W
Feb 2002 57 5 (many) 400 (24) W
Mar 2002 732 51 (30) 300 (4, 25) W
Apr 2002 979 103 (9) 600 (29) W
May 2002 953 49 (9) 700 (28) W
Jun 2002 1434 360 (22) 1000 (2, 24) W
Jul 2002 1499 119 (9) 500 (many) W
Aug 2002 1464 176 (9) 1500 (6) W
Sep 2002 1358 243 (18) 600 (19) W
Oct 2002 837 40 (6) 700 (12) W
Nov 2002 630 40 (11) 400 (6) W
Dec 2002 601 58 (22) 300 (23, 26) W
Jan 2003 775 42 (20) 500 (20, 30) W
Feb 2003 594 43 (3) 500 (19) W, GW (6)
Mar 2003 614 41 (15) 300 (20, 30) W
Apr 2003 458 31 (18) 400 (22) W, GW (7, 18)

Geologic Background. Asamayama, Honshu's most active volcano, overlooks the resort town of Karuizawa, 140 km NW of Tokyo. The volcano is located at the junction of the Izu-Marianas and NE Japan volcanic arcs. The modern Maekake cone forms the summit and is situated east of the horseshoe-shaped remnant of an older andesitic volcano, Kurofuyama, which was destroyed by a late-Pleistocene landslide about 20,000 years before present (BP). Growth of a dacitic shield volcano was accompanied by pumiceous pyroclastic flows, the largest of which occurred about 14,000-11,000 BP, and by growth of the Ko-Asama-yama lava dome on the east flank. Maekake, capped by the Kamayama pyroclastic cone that forms the present summit, is probably only a few thousand years old and has an historical record dating back at least to the 11th century CE. Maekake has had several major plinian eruptions, the last two of which occurred in 1108 (Asamayama's largest Holocene eruption) and 1783 CE.

Information Contacts: Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/).