Report on Lewotobi (Indonesia) — April 2009
Bulletin of the Global Volcanism Network, vol. 34, no. 4 (April 2009)
Managing Editor: Richard Wunderman.
Lewotobi (Indonesia) Drops in steaming and seismicity during March 2009
Please cite this report as:
Global Volcanism Program, 2009. Report on Lewotobi (Indonesia). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 34:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200904-264180.
8.542°S, 122.775°E; summit elev. 1703 m
All times are local (unless otherwise noted)
Unrest caused authorities to elevate the alert level here to 2 in May 2008 (BGVN 34:01). No ash emissions were reported, as has been the case since 2003 (BGVN28:06, 28:10, 34:01).
On 23 March 2009, the Center for Volcanology and the Mitigation of Geologic Disaster (CVGHM) lowered the alert level on Lewotobi from 2 to 1 (on a scale of 1-4). This shift was based on visual observations and decreased seismicity during March. Rarely seen diffuse white plumes rose 25 m above the crater and drifted E. Visitors and residents continued to be advised not to approach the crater.
Over the period 1-23 March 2009 a cluster of shallow volcanic earthquakes occurred. Their initial numbers, 5-25 daily, soon declined to 1-5 occurrences per day. The total number of deep volcanic earthquakes did not change, averaging 1-3 daily. No tremor had been recorded since 1 February 2009 and at least as late as mid-2009.
Geologic Background. The Lewotobi "husband and wife" twin volcano (also known as Lewetobi) in eastern Flores Island is composed of the Lewotobi Lakilaki and Lewotobi Perempuan stratovolcanoes. Their summits are less than 2 km apart along a NW-SE line. The conical Lakilaki has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has erupted only twice in historical time. Small lava domes have grown during the 20th century in both of the crescentic summit craters, which are open to the north. A prominent flank cone, Iliwokar, occurs on the E flank of Perampuan.
Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); 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/); Agence France-Presse (URL: http://www.afp.com/); Jakarta Post (URL: http://www.thejakartapost.com/).