New thermoluminescence age estimates for the Nyos maar eruption (Cameroon Volcanic Line)

• Published in: PloS one Vol. 12; no. 5; p. e0178545
• Main Authors: Schmidt, Christoph, Tchouankoue, Jean Pierre, Nkouamen Nemzoue, Peguy Noel, Ayaba, Félicité, Nformidah-Ndah, Siggy Signe, Nformi Chifu, Emmanuel
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.05.2017; Public Library of Science (PLoS)
• Subjects: Age; Analysis; Bedrock; Biology and Life Sciences; Cameroon; Dams; Data processing; Dating techniques; Deposits; Dosage; Earth science; Earth Sciences; Ecology and Environmental Sciences; Emission analysis; Geology; Hazard assessment; Hazard mitigation; Lava; Local population; Luminescence; Methods; Minerals; People and Places; Physical Sciences; Quartz; Risk assessment; Size distribution; Social Sciences; Thermoluminescence; Volcanic Eruptions; Volcanoes; Cameroon
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0178545

Nyos maar is located in the Cameroon Volcanic Line and generates a multitude of primary and secondary hazards to the local population. For risk assessment and hazard mitigation, the age of the Nyos maar eruption provides some vital information. Since previous dating efforts using a range of techniques resulted in vastly varying eruption ages, we applied thermoluminescence (TL) methods to obtain independent and direct chronological constraints for the time of maar formation. Target minerals were granitic quartz clasts contained in pyroclastic surge deposits. Thermoluminescence plateau results prove that heat and/or pressure during the phreatomagmatic eruption was sufficient to reset the inherited luminescence signal of granitic bedrock quartz. Parallel application of three TL measurement protocols to one of the two samples gave consistent equivalent doses for the quartz ultra-violet emission. Despite the robustness of our dose estimates, the assessment of the dose rate was accompanied by methodological challenges, such as estimation of the original size distribution of quartz grains in the pyroclastic deposits. Considering results from additional laboratory analyses to constrain these uncertainties, we calculate an average maximum TL age of 12.3 ± 1.5 ka for the Nyos maar eruption. Based on these new data, a more solid risk assessment can be envisaged.