Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 2, February 1995

Barren Island (Andaman Islands)  New eruption on 20 December; lava
       flows reach the ocean

Barren Island
Andaman Islands, Indian Ocean, India
12.29N, 93.88E; summit elev. 305 m

A new eruption at Barren Island was first noticed by the Indian
Navy on 20 December 1994. A team composed of scientists from the
Geological Survey and Zoological Survey of India arrived at the
island early on 24 January, and an aerial survey over the volcano
was made on the 31st. As of 22 February, this mainly Strombolian
eruption was still "in its initial stage, gradually gaining
momentum."

During January and February, thick clouds of pale brownish gas,
dark ash particles, and white steam from the crater area were
rising ~200 m at intervals of 30 seconds, accompanied by continuous
rumbling and intermittent "cracking" sounds. Two new vents were
active, the first within the main crater near the SW corner, and
the second ~50 m from the summit down the SW flank. The eruption is
believed to have started from the flank vent, around which a new
100-m-diameter subsidiary crater had formed.

Incandescent material (cinder and volcanic bombs) rising to heights
of 20 m could be seen from 4 km offshore. Particles ranged in size
from a few cubic centimeters to ~1 m^3, with the average size being
slightly less than 10 cm^3. Ejecta filled a valley on the S side of
the western-most 1991 lava bed. Lava flows travelled ~1.5 km from
the active vents into the sea, producing profuse steaming at the
ocean entry. The moving lava front was ~50 m wide and 6 m thick by
22 February. Megascopically the lava was basaltic andesite, similar
to that erupted during September 1991, with a high percentage of
large plagioclase phenocrysts and frequent olivine in a dark-gray
glassy groundmass.

On 9 March at around 0530 GMT astronauts on the Space Shuttle
noticed a small plume rising from Barren Island. They made a short
video recording (~15 seconds) showing a V-shaped plume that
extended for ~3 km before dispersing. Visible imagery from the
NOAA-14 (at 0730 GMT) and GMS (0430-0830 GMT) satellites failed to
reveal a volcanic plume. A photograph taken from the Shuttle on 14
March at 0749 GMT again showed a small plume blowing W towards the
Andaman Islands (figure 1). As this issue went to press, an
aviation notice to airmen (NOTAM) on 27 March stated that the
intensity of the eruption was unpredictable and advised all
aircraft to avoid overflying the area.

Located ~135 km NE of Port Blair (South Andaman Island), Barren
Island contains a 1.6-km-wide somma open to the W with a central
pyroclastic cone that was the source of historical eruptions
reported in 1787, 1789, 1795, 1803-04, possibly 1852, and 1991.
Lava flows from the 1803 and 1991 eruptions reached the coast. The
1991 eruption began in late April with hot gases and strong ash
emissions and ended in late October (Bulletin v. 16, nos. 5, 8, 10,
12, and v. 17, nos. 1 & 5). Initial activity was from a vent on the
upper NE flank of the central cone, but expanded to include the
main crater. Basaltic andesite lava flows covered an area of about
1,600 m^2 to an average thickness of 5-6 m. Gas emissions were
observed from lava flows near the NW coast in April 1993 (Bulletin
v. 18, no. 9).

Information Contacts: Director General, Geological Survey of India,
27 Jawaharlal Nehru Road, Calcutta -700016, India; Cindy Evans,
Space Shuttle Earth Observations Office, Mail Code C102, Lockheed
Engineering & Sciences, P.O. Box 58561, Houston, TX 77258 USA
(Email: evans@sn.dnet.nasa.gov); Jim Lynch, NOAA/NESDIS Synoptic
Analysis Branch, Room 401, 5200 Auth Road, Camp Springs, MD 20746
USA.

Figure 1. Oblique photograph of the Barren Island eruption plume
taken from the Space Shuttle, 14 March 1995 at 0749 GMT, looking
NW. Ash plume is blowing generally W towards the Andaman Islands.
NASA photograph STS 067-721A-052. Courtesy of Cindy Evans.