Eruptive and earthquake activities related to the 2000 eruption of Mount Cameroon volcano (West Africa) |
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| Authors: | B Ateba C Dorbath L Dorbath N Ntepe M Frogneux FT Aka JV Hell JC Delmond D Manguelle |
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| Institution: | 1. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan;2. Department of Mines, Ministry of Mines, Industry and Technological Development, P.O. Box 70, Yaoundé, Cameroon;3. Institute of Mining and Geological Research, P.O. Box 4110, Yaoundé, Cameroon;4. Graduate School of Science, Hokkaido University, N10W8 Kita-ku, Sapporo, 060-0810, Japan;5. Department of Chemistry, School of Science, Tokai University, Hiratsuka 259-1211, Japan;6. Department of Earth Sciences, University of Dschang, Cameroon;7. Higher Teachers'' Training College, Bambili, University of Bamenda, P.O. Box 39, Bambili, Cameroon;1. Laboratoire d''Hydrologie et de Géochimie de Strasbourg, EOST, Université de Strasbourg et CNRS, 1, rue Blessig, 67084 Strasbourg Cedex, France;2. Bureau de Recherches Géologiques et Minières (BRGM), 3 av. Guillemin, 45060 Orléans Cedex, France;3. GEOTOP, Université du Québec à Montréal, CP 8888, Succ Centre Ville, Montréal, Qc, H3C 3P8, Canada;4. Institut de Minéralogie et de Physique des Milieux Condensés, Université Pierre et Marie Curie, CNRS, IRD, 4 Place Jussieu, 75005, Paris, France;1. GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, D-24148 Kiel, Germany;2. Department of Geology, Faculty of Science, University of Buea, P. O box 63, SW Region, Cameroon;3. Mt. Cameroon Observatory, Institute for Geological and Mining Research, P.O box 370, Buea, SW Region, Cameroon;4. Institute of Geosciences, Christian Albrechts University Kiel, Ludewig-Meyn-Str.10, D-24118 Kiel, Germany;1. Geowissenschaftliches Zentrum, Georg-August-Universität, Göttingen, Germany;2. Dipartimento di Scienze della Terra, dell''Ambiente e delle Risorse, University Federico II of Naples, Italy;3. Istituto Nazionale di Geofisica e Vulcanologia - sezione di Napoli Osservatorio Vesuviano, Naples, Italy;4. Istituto Nazionale di Geofisica e Vulcanologia - sezione di Palermo, Italy;5. Department of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology, Trondheim, Norway |
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| Abstract: | Mount Cameroon is an active volcano located in the Gulf of Guinea, west of Central Africa. After the March–April 1999 eruption on the SW flank, another eruption of the volcano occurred in 2000. It took place from three sites on the southwest flank and near the summit. The first eruptive site was located 500 m to the southwest of the summit, at 3900 m altitude. Activity on this site was mainly explosive with no lava flow. The second site was located between 3220 and 3470 m altitude. Lava was emitted along NNE–SSE fissures from this site and flew towards Buea, the main city of the area, stopping ~ 4 km from the first houses. The last site was located in the south western flank at 2750 m altitude. The lava ejected from an old cone near the first 1999 eruptive site was divided into two branches, for a total length of around 1 km. The location of active volcanic cones in 1999 and 2000 seems to be linked to the local tectonics. The pre-eruptive period was characterized by a seismic swarm which may be a precursor recorded in March 2000 by an analogue seismic station. The main shock was a magnitude 3.2 event, and was felt by the population in Ekona town located on the eastern flank. It had a Modified Mercalli intensity of III–IV. When the eruption started, a temporary network of short period 3-component seismic stations was set up around the volcano to improve the monitoring of seismic activity. The co-eruptive period from late May to September was characterized by sequences of earthquake swarms, volcanic tremor and a family of earthquakes having similar waveform and appearing regularly in August and early September. Some of the earthquakes were felt by the population in Buea and its environments. The largest seismic event recorded had a magnitude of 4. During the post-eruptive period from mid-September to December, seismicity returned to its background level of 1–3 earthquakes per 3 days. Hypocenter locations reveal a linear narrow structure under the summit zone which could represent the magmatic conduit of the volcano. The frequency/magnitude relationship revealed a b-value of 1.43 higher than those previously determined, but more representative of volcanic media. Seismic energy release was gradual after the 2000 eruption started. |
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