Report on Nyiragongo (DR Congo) — January 2009
Bulletin of the Global Volcanism Network, vol. 34, no. 1 (January 2009)
Managing Editor: Richard Wunderman.
Nyiragongo (DR Congo) Lava lake and seismicity elevated in October 2008; lava lake persists into 2009
Please cite this report as:
Global Volcanism Program, 2009. Report on Nyiragongo (DR Congo). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 34:1. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200901-223030.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
Previous evidence and observations indicated continued activity at Nyiragongo's summit crater lava lake through August 2007 (BGVN 32:08). MODVOLC thermal alerts have been detected over Nyiragongo nearly daily for at least the past 5 years, as late as January 2009, an indication of the persistence of the summit crater's lava lake.
John Seach climbed to the summit crater in August 2008 and saw the active lava lake, including surface currents and fountaining.
In a Die Welt news story, Kasereka Mahinda, director of the the Goma Geophysical Observatory, stated that during a visit to the crater in October 2008, a noticeable rise in the magma level of the lava lake was observed, and recent earthquakes had been felt. Much of the observatory's monitoring equipment has been looted by local civil war combatants, Mahinda explained. The war thus made instrument-based assessments impossible and prevents new instrument installations.
Gas analyses. Sawyer and others (2008) discuss the composition and flux of gas from Nyiragongo by ground-based remote-sensing techniques during mid-2005 through mid-2007. Ultraviolet spectroscopic measurements in May/June 2005 and January 2006 indicated respective average SO2 emission rates of 38 and 23 kg/s. Open-path Fourier transform infrared spectroscopic measurements obtained in May/June 2005, January 2006, and June 2007 indicated respective average molar proportions of 70, 24, 4.6, 0.87, 0.26, 0.11, and 0.0016% for H2O, CO2, SO2, CO, HCl, HF, and OCS (carbonyl sulfide). The plume compositions were similar in a 24-month span during 2005-2007, with little temporal variation in CO2, SO2, and CO proportions. This stability persisted despite variable degassing from the lava lake, including Strombolian bursts and lava fountains, and variations in the SO2 emission rate.
Reference. Sawyer, G. M., Carn, S. A., Tsanev, V.I., C. Oppenheimer, C., and Burton, M., 2008, Investigation into magma degassing at Nyiragongo volcano, Democratic Republic of the Congo: Geochem. Geophys. Geosyst., v. 9, Q02017, doi:10.1029/2007GC001829.
Geologic Background. One of Africa's most notable volcanoes, Nyiragongo contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. In contrast to the low profile of its neighboring shield volcano, Nyamuragira, 3470-m-high Nyiragongo displays the steep slopes of a stratovolcano. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 parasitic cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.
Information Contacts: John Seach, New South Wales, Australia (URL: http://www.volcanolive.com/); Observatoire Volcanologique de Goma, Departement de Geophysique, Centre de Recherche en Sciences Naturelles, Lwiro, D.S. Bukavu, DR Congo (Email: email@example.com); 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://hotspot.higp.hawaii.edu/); Die Welt (URL: http://www.welt.de/welt_print/article2721874/Ein-Vulkan-kurz-vor-dem-Ausbruch.html).