Abstract
Scientific visits to Lake Nyos in Northwestern Cameroon in the aftermath of the gas disaster that killed over 1,750 people in 1986 revealed the presence of a pyroclastic natural dam in the northern border of the lake. This dam is being affected by back erosion. Collapse of the dam could cause a flood that would affect inhabited areas over a 220 km distance. Timing of dam collapse has been hotly debated based on vastly different carbon-14 and potassium-argon formation ages. In previous work, we used uranium series disequilibria to suggest a formation age of >5,000 years. Detailed comparison of uranium series and trace element data for lavas of Lake Nyos and Mt. Cameroon, both belonging to the Cameroon Volcanic Line, suggests that Lake Nyos basalts erupted with an initial radium-226/thorium-230 ratio that is two times higher than lavas erupting on Mt. Cameroon today. This information is used to infer an age of 8,750 ± 490 years, which we suggest is the formation age of the Lake Nyos dam. The erosion rate deduced from this age does not indicate that collapse of the dam from back erosion alone and the attendant potential flood disaster are as eminent and alarming as previously thought. However, other factors militate for action to secure the dam. Work is underway to reinforce it by engineering methods.
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References
Aka FT, Yokoyama T, Kusakabe M, Nakamura E, Tanyileke G, Ateba B, Ngako V, Nnange JM, Hell JV (2008) U-series dating of Lake Nyos maar basalts, Cameroon (West Africa); implications for potential hazards on the Lake Nyos dam. J Volcanol Geotherm Res 176:212–224
Ateba B, Dorbath C, Dorbath L, Ntepe N, Frogneux M, Aka FT, Hell JV, Delmond JC, Manguelle D (2009) Eruptive and earthquake activities related to the 2000 eruption of Mount Cameroon volcano (West Africa). J Volcanol Geotherm Res 179:206–216
Condomines M, Hémond CH, Allègre CJ (1988) U-Th–Ra radioactive disequilibria and magmatic processes. Earth Planet Sci Lett 90:243–262
Condomines M, Gauthier PJ, Tanguy JC, Gertisser R, Thouret JC, Berthommier P, Camus G (2005) 226Ra or 226Ra/Ba dating of Holocene volcanic rocks: application to Mt. Etna and Merapi volcanoes. Earth Planet Sci Lett 230:289–300
Demidjuk Z, Turner S, Sandiford M, George R, Foden J, Etheridge M (2007) U-series isotopes and geodynamic constraints on mantle melting processes beneath the newer Volcanic province in South Australia. Earth Planet Sci Lett 261:517–533
Freeth SJ (1988) When the Lake Nyos dam fails there will be serious flooding in Cameroon and Nigeria—but when will it fail? EOS Trans Am Geophys Union 69(32):776–777
Freeth SJ, Rex DC (2000) Constraints on the age of Lake Nyos, Cameroon. J Volcanol Geotherm Res 97:261–269
Ivanovich M, Harmon SR (1992) Uranium-series disequilibrium: applications to earth, marine and environmental sciences. Oxford Univ Press, NY
Joint UNEP/OCHA Environment Unit (2005) Lake Nyos dam assessment, Cameroon. http://www.reliefweb.int/library/documents/2005/ocha-cmr
Kümpel HJ (1993) About the dam of lake Nyos. In: Freeth SJ (ed) Newsletter of the international working group on Crater Lakes 6, pp 43–47
Kusakabe M, Ohba T, Issa, Yoshida Y, Satake H, Ohizumi T, Evans WC, Tanyileke G, Kling GW (2008) Evolution of CO2 in Lakes Monoun and Nyos, Cameroon, before and during controlled degassing. Geochem J 42:93–118
Le Guern F, Sigvaldason GE (1989) (eds) The Lake Nyos event and natural CO2 degassing 1. J Volcanol Geotherm Res 39:95–275
Lockwood JP (1988) Lake Nyos dam: reply. EOS Trans Am Geophys Union 69(32):776–777
Lockwood JP, Rubin M (1989) Origin and age of Lake Nyos maar, Cameroon. J Volcanol Geotherm Res 39:117–124
Lockwood JP, Costa JE, Tuttle ML, Tebor SG (1988) The potential for catastrophic dam failure at Lake Nyos maar, Cameroon. Bull Volcanol 50:340–349
McKenzie D (1985) 230Th–238U disequilibrium and the melting processes beneath ridge axes. Earth Planet Sci Lett 72:149–157
Ntepe N, Aka FT, Ubangoh RU, Ateba B, Nnange JM, Hell JV (2004) The July 2002 earthquake in the Kribi region: geological context and a preliminary evaluation of seismic risk in southwestern Cameroon. J Afr Earth Sci 40:163–172
Rubin KH, MacDougall JD (1990) Dating of neovolcanic MORB using (226Ra/230Th) disequilibria. Earth Planet Sci Lett 101:313–322
Sigurdsson H, Devine ID, Tchoua FM, Presser TS, Pringle MK, Evans WC (1987) Origin of the lethal gas burst from Lake Monoun, Cameroon. J Volcanol Geotherm Res 31:1–16
Spatial Data Infrastructure—2010 Africa newsletter 9(12) 5. (http://www.gsdi.org/newsletters.php)
Tabot CT, Fairehead JD, Stuart GW, Ateba B, Ntepe N (1992) Seismicity of the Cameroon volcanic line, 192–1990. Tectonophysics 212:303–320
Walker AB, Redmayne DW, Browitt CWA (1988) Seismic monitoring of Lake Nyos, Cameroon, following the gas release disaster of August 1986. BGS-Global Seismol. Intern. Rep. WL/88/14
Yokoyama T, Aka FT, Kusakabe M, Nakamura E (2007) Plume-lithosphere interaction beneath Mt. Cameroon volcano, West Africa: constraints from 238U–230Th-226Ra and Sr-Nd-Pb isotopic systematics. Geochim Cosmochim Acta 71:1835–1854
Acknowledgments
Samples were collected from Lake Nyos using funds from the 2003 Monbusho International Scientific Research Program (#16403012) to Emeritus Professor Minoru Kusakabe (standing in a pothole on Fig. 1c). Analyses were done at the Okayama University Institute for Study of the Earth’s Interior (ISEI) in Japan when AFT was on a ‘mis à la disposition’ of ISEI from the Cameroon Ministry of Scientific Research and Innovation (MINRESI). Work at ISEI was supported by COE-21 research grants to Prof. Eizo Nakamura and also by JSPS grants for ‘Asia–Africa Science Platform Program’ (AASPP - Geochemistry of Lake Nyos gas disaster, Cameroon Volcanic Line-Rift Valley volcanoes and the underlying mantle). Collaboration from colleagues and administration of ISEI is acknowledged. Pictures shown in this article were taken during many trips to Lake Nyos within the framework of (1) the Lakes Nyos and Monoun Degassing Project funded by the Government of Cameroon, USAID and the French Cooperation; (2) SATREPS-IRGM project headed by Prof. Takeshi Ohba of Tokai University (Japan) and funded by the Government of Cameroon, the Japan International Cooperation Agency (JICA) and the Japan Science and Technology Agency (JST); (3) the Lake Nyos dam reinforcement project funded by the Government of Cameroon & the European Union. We acknowledge the leadership of MINRESI, through IRGM (Drs. Joseph Hell, Luc Sigha and Greg Tanyileke) that coordinates all these projects. Review comments from Prof. J. P. Lockwood and an anonymous reviewer are thankfully acknowledged.
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Aka, F.T., Yokoyama, T. Current status of the debate about the age of Lake Nyos dam (Cameroon) and its bearing on potential flood hazards. Nat Hazards 65, 875–885 (2013). https://doi.org/10.1007/s11069-012-0401-4
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DOI: https://doi.org/10.1007/s11069-012-0401-4