Batu Tara has been active since January 2007, with thermal anomalies and occasional low-level ash plumes at least through 24 November 2009. This report discusses activity since our previous report (BGVN 34:01), which covered activity through 10 March 2009.

Since 10 March 2009, the eruption of low-level ash plumes has continued at least through 24 November 2009. Many reports of Batu Tara plumes came from the Darwin Volcanic Ash Advisory Centre (table 3).

Table 3. Summary of Volcanic Ash Advisories for Batu Tara reported by the Darwin Volcanic Ash Advisory Centre (VAAC) during 11 March 2009-24 November 2009. Many of these plumes were described as ash plumes. This table continues the table in BGVN 34:01. Courtesy of the Darwin VAAC.

NASA's Earth Observatory described the scene from an image taken on 30 April 2009 (figure 5). "In this true-color picture, Batu Tara looks like a small, smoking speck in the Flores Sea. Initially blowing toward the NW, the volcanic plume changes direction multiple times, forming a large question-mark shape, mingling with clouds in the N. When volcanic gases mingle with oxygen and moisture in the presence of sunlight, vog, or volcanic smog, often results. The off-white color and diffuse shape of the volcanic plume in the N are suggestive of vog." MODVOLC recorded thermal alerts at Batu Tara on 26 and 29 May, and 3 July 2009.

Figure 5. Image of plume from Batu Tara taken on 30 April 2009 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite. Plume extends W and NW. Courtesy NASA Earth Observatory.

Geological Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km N of Lembata (fomerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks to within 50 m of the summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption, during 1847-52, produced explosions and a lava flow.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); NASA Earth Observatory (URL: http://earthobservatory.nasa.gov/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).