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) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200311-283110
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) |
Geological Summary. 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 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-Asamayama 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 observed activity 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/).