Crustal structure beneath two seismic broadband stations revealed from teleseismic P-wave receiver function analysis in the Virunga volcanic area,Western Rift Valley of Africa |
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| Institution: | 1. Mercator & Ortelius Research Centre for Eruption Dynamics, Geology Department, Ghent University, Belgium;2. Geophysical Department, National Museum of Natural History, Luxembourg;3. Geology Department, Royal Museum for Central Africa, Tervuren, Belgium;4. Earth Sciences Department, University of Addis Ababa, Ethiopia;5. Department of Earth & Environmental Sciences, University of Rochester, USA;6. Environmental Sciences Department, Università di Napoli II, Italy;7. Istituto Nazionale di Geofisica e Vulcanologia (INGV), Roma, Italy;8. Goma Volcano Observatory, Democratic Republic of Congo;9. School of Earth & Environment, University of Leeds, UK;10. Department of Earth & Atmospheric Sciences, Purdue University, USA;1. Institute of Drug Discovery and Technology, Ningbo University, Ningbo 315211, China;2. Department of Chemistry, Zhejiang University, Hangzhou 310028, China;3. School of Material Science and Chemical Engineering, Ningbo University, Ningbo 315211, China;4. Department of Environmental Engineering, Wuchang University of Technology, Wuhan 430223, China;1. Géosciences Montpellier, UMR 5243, Université de Montpellier, Université des Antilles, CNRS, place Eugène Bataillon, 34095 Montpellier cedex 05, France;2. Géosciences Montpellier, UMR 5243, Université des Antilles–Université de Montpellier–CNRS, Campus de Fouillole, 97170, Pointe-à-Pitre, FWI, France;3. Département des Sciences de la Terre, Ecole Nationale Supérieure des Mines, Rabat, Morocco;4. laboratoire des Géosciences Appliqués LGA, Université Mohamed 1er, faculté des sciences, Oujda, Morocco;5. Département de Géologie, Université Abdelmalek Esaadi, 93003 Tetuán, Morocco;1. Géosciences Montpellier, UMR5243, Université de Montpellier, Montpellier, France;2. School of Earth and Ocean Sciences, University of Victoria, Victoria BC, Canada;3. Scientific Institute, Mohammed V University, Rabat, Morocco;4. International Centre for Theoretical Physics, Trieste, Italy;5. Faculté des Sciences et Techniques de Tanger, Tanger, Morocco;1. Higher Polytechnic School, University of Almeria, 04120 Almeria, Spain;2. Faculté Polidisciplinaire d''Errachidia, University of Moulay Ismaïl, B.P. 509 Boutalamine, Morocco;3. NAGET (North Africa Geophysical and Tsunami Group), Algeria;4. National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Egypt;5. Scientific Institute, Mohammed V University, Rabat, Morocco;1. Lithosphere Fluid Research Lab, Institute of Geography and Earth Sciences, Eötvös University Budapest, 1117 Pázmány Péter sétány 1/c, Hungary;2. MTA-EPSS FluidsByDepth Lendület Research Group, Institute of Earth Physics and Space Science (EPSS), Eötvös Loránd Research Network, Sopron, 9400 Csatkai Endre utca 6-8, Hungary;3. Institute of Geography and Earth Sciences, Department of Geology and Meteorology, Faculty of Sciences, University of Pécs, Ifjúság u. 6, Pécs 7624, Hungary;4. College of Earth Sciences and Engineering, Department of Geology, University of Dodoma, P. O. Box, 11090, Dodoma, Tanzania;5. Research School of Earth Sciences, Australian National University, Building 142, Mills Road, Acton, ACT 2601, Australia |
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| Abstract: | The shear velocity structure beneath the Virunga volcanic area was estimated by using an average solution in the time domain inversion of stacked teleseismic receiver functions provided by two seismic broadband stations KUNENE (KNN) and KIBUMBA (KBB). These two stations are 29 km apart and located at the eastern and western escarpment of the Western Rift Valley of Africa in the Virunga area, respectively. The velocity model was presented as P-wave velocity models. From these models, the crust mantle transition zone beneath the area sampled by KNN and KBB in the Virunga area was determined at depth from about 36 to 39 km and 30 to 41 km, respectively. A low velocity zone was observed below stations KNN and KBB at depths between 20–30 km and 18–28 km, respectively, and with average velocity 5.9 km/s and 6.0 km/s. This low velocity zone may probably related to a magma chamber or a melt-rich sill. The models show also high velocity material (6.8–7.4 km/s) lying beneath stations KNN and KBB at depths 3–20 km and 3–10 km, respectively, which is indicative of magma cumulates within the volcanic edifice. The result obtained in this study was applied to the determination of epicentres during the period prior to the 27 November 2006 Nyamuragira eruption. This eruption was preceded by a swarm of hybrid volcanic earthquakes with clear P-waves onset. Using the receiver function model was found to improve the location of events. The located events correlate well with the location of the eruptive site and data provided by the INSAR observations of surface deformation associated with eruption. |
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