Global Volcanism Program

20 July-26 July 2011

Based on pilot observations and analyses of satellite imagery, the Wellington VAAC reported that on 19 July an ash plume from Ambrym rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 185 km NW.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

Available Weekly Reports

20 July 2011 Back to Top

Based on pilot observations and analyses of satellite imagery, the Wellington VAAC reported that on 19 July an ash plume from Ambrym rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 185 km NW.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

22 June 2011 Back to Top

On 27 June, the Vanuatu Geohazards Observatory reported that data collected from Ambrym's monitoring network showed significant degassing daily and occasional explosions in the crater. Field observers noted that the level of the lava lakes was high. During June, villages reported minor ashfall and that acid rain affected vegetables in some areas W, S, and E. The Alert Level remained at 1 (on a scale of 0-4).

Sources: Vanuatu Geohazards Observatory

18 August 2010 Back to Top

Based on pilot observations, analyses of satellite imagery, and information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported that on 8 and 10 August ash-and-steam plumes from Ambrym rose to an altitude 6.1 km (20,000 ft) a.s.l. and drifted W and NW.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

3 March 2010 Back to Top

Based on pilot observations and analyses of satellite imagery, the Wellington VAAC reported that ash plumes from Ambrym rose to an altitude of 2.4 km (8,000 ft) a.s.l. on 5 March.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

2 December 2009 Back to Top

On 3 December, a diffuse plume from Ambrym, likely largely composed of sulfur dioxide, was visible on satellite imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) and posted on NASA's Earth Observatory website.

Sources: NASA Earth Observatory

25 March 2009 Back to Top

Based on information from the Port Vila airport tower, the Wellington VAAC reported that on 25 March an ash plume from Ambrym rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted about 55 km S. The next day, a pilot reported that "smoke" rose to an altitude of 2.4 km (8,000 ft) a.s.l. Ash was not identified on satellite imagery.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

2 May 2007 Back to Top

The Wellington VAAC reported that a pilot observed an ash plume from Ambrym on 3 May. The plume rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE. Ash was visible on satellite imagery.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

25 April 2007 Back to Top

The Wellington VAAC reported that an ash plume from Ambrym was visible on satellite imagery on 1 May. The altitude and direction of the plume were not reported.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

28 March 2007 Back to Top

The Wellington VAAC reported that on 3 April pilots observed lava and ash emissions from Ambrym. Ash plumes rose to altitudes below 2.4 km (8,000 ft) a.s.l.

Sources: Wellington Volcanic Ash Advisory Center (VAAC)

31 March 2004 Back to Top

According to a report from John Seach, during March an active lava lake was present in Ambrym's Mbwelesu crater.

Sources: Volcano Live

Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date	Stop Date	Eruption Certainty	VEI	Evidence	Activity Area or Unit
2008 May 23	2011 (continuing)	Confirmed	1	Historical	Benbow and Marum
2006 Nov 8	2007 Dec 27 (in or after)	Confirmed	1	Historical	Marum (Mbwelesu)
1996 Jun (in or before)	2005 Aug (in or after)	Confirmed	1	Historical	Benbow, Marum, Niri Mbelesu, Mbwelesu
1994 Dec (in or before)	Unknown	Confirmed	1	Historical	Benbow and Marum
1990 Sep (in or before)	1991 Jul (in or after)	Confirmed	2	Historical	Mbwelesu, Niri Mbwelesu, Niri Taten
1989 Apr 24	1989 Dec 23	Confirmed	2	Historical	Marum, Benbow, Niri Mbwelesu Taten
1988 Feb 12 (?)	1988 Aug 23	Confirmed	3	Historical	Benbow, Mbwelesu, Marum, Niri Taten
1986 Nov 13	1986 Nov 19 (?)	Confirmed	2	Historical	New cone 3 km east of Marum
1984	1986 Mar 8 (in or after)	Confirmed	2	Historical
1983	Unknown	Confirmed	2	Historical	Marum
1981 Feb 20	1981 Sep 30	Confirmed	2	Historical	Benbow, Marum
1980 May 16	1980 Aug 18	Confirmed	2	Historical	Marum
1979 Jun 6	1979 Sep (?)	Confirmed	2	Historical	Benbow, Marum
1979 Jan 26 ± 5 days	1979 Feb 18 (?)	Confirmed	2	Historical	Benbow
1977 Aug	1977 Sep 30	Confirmed	2	Historical
1977 Jan 20 ± 5 days	1977 Jan 28 (?)	Confirmed	2	Historical
1973 Apr 15 ± 5 days	1976 Oct 14	Confirmed	2	Historical	Benbow, Mbuelesu, Marum
1972 Apr 15	1972 Aug 15	Confirmed	2	Historical	Benbow, Marum
1971 Feb 3	1971 Nov 5	Confirmed	2	Historical	Marum, Benbow
1967 Jul	1970 Aug 29	Confirmed	2	Historical	Marum, Benbow, Mbuelesu
1964 Feb (?)	1966 Sep (in or after)	Confirmed	2	Historical	Marum, Benbow
1963 Aug 30	1963 Sep 23 (in or after)	Confirmed	2	Historical	Benbow, Marum
1961 Aug 15	1963 Apr 3	Confirmed	1	Historical	Benbow, Marum, south of Marum
1960 Sep 17	Unknown	Confirmed	1	Historical	Mbuelesu, Benbow, near Marum
1959 Apr	Unknown	Confirmed	2	Historical	Marum
1958 Nov 18	Unknown	Confirmed	2	Historical	Benbow and Marum
1957 Aug 26 ± 5 days	1957 Oct	Confirmed	1	Historical	Benbow, Marum
1955	Unknown	Confirmed	2	Historical	Benbow
1954	Unknown	Confirmed	2	Historical	Benbow
1953 May	1953 Oct 13 (?)	Confirmed	2	Historical	Benbow, Mbuelesu, S flank of Benbow
1952 Aug 10	1952 Dec 26 ± 5 days	Confirmed	2	Historical	Benbow
1950 Dec 6	1951 Nov 25 ± 5 days	Confirmed	3	Historical	Benbow
1942 Jun 6	Unknown	Confirmed	2	Historical	NW flank of Benbow
1938	Unknown	Confirmed	2	Historical	Benbow, Marum ?
1937 Mar 27	1937 Apr	Confirmed	2	Historical	Benbow and west flank
1935 Sep	1936 Jan	Confirmed	2	Historical	Benbow
1929 Jun 28	1929 Jul 1	Confirmed	2	Historical	Benbow, west flank, Marum
1915 Oct 20	Unknown	Confirmed	2	Historical	Marum, crater at SE point
1913 Oct 14	1914	Confirmed	2	Historical	Benbow, west flank, Marum
1912	Unknown	Confirmed		Historical	Marum ?, west flank ?
1910	Unknown	Confirmed	0	Historical	Base of Marum
1909 Jul 28 (?)	Unknown	Confirmed	2	Historical
1908	Unknown	Confirmed	2	Historical
1898 Mar 26	Unknown	Confirmed	1	Historical
1894 Oct 15	1895 Feb 10 (in or after)	Confirmed	3	Historical	Benbow and west flank
1888 Feb 24 ± 4 days	1888 Apr (?)	Confirmed	2	Historical	SE flank (6 km from SE Point), Marum
1886 Jul	Unknown	Confirmed	2	Historical
1884	Unknown	Confirmed	2	Historical	Marum and/or Benbow
1883	Unknown	Confirmed	2	Historical	Marum
1871	Unknown	Confirmed	2	Historical
[ 1870 ]	[ Unknown ]	Uncertain
1863	1864	Confirmed	2	Historical
1820 (?)	Unknown	Confirmed		Historical	West flank
1774	Unknown	Confirmed	2	Historical
50 ± 100 years	Unknown	Confirmed	6	Radiocarbon (uncorrected)

Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.