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Title: Investigations of Nyamuragira and Nyiragongo volcanoes (DRC), using Interferometric Synthetic Aperture Radar
Author: Colclough, S. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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InSAR was used to remotely prospect for ground deformation and to map lava flows associated with eruptions at Nyamuragira and Nyiragongo volcanoes (DRC). Eleven ERS SAR scenes were obtained. Initial InSAR results revealed excellent interferometric coherence over barren lava surfaces, although coherence was limited over vegetated areas and on the steep upper slopes of the volcanoes. This resulted in isolated patches of coherence, which despite significant modifications to the processing technique, could not be bridged during the unwrapping of the interferograms. However, reliable results were achieved by processing the isolated areas separately. New areas of interferometric coherence enabled lava flows emplaced during the 2002 Nyiragongo, and 1998 and 2001 Nyamuragira eruptions to be identified and mapped in higher detail than was available in existing maps. Based on the mapped flow areas and assumed flow thicknesses, minimum estimates for the erupted volumes were found to be 22 x 106 m3, 71 x 106 m3 and 133 x 106 m3, respectively. Previously undetected deformation signals were found over both long (years) and short (weeks) time-periods. A persistent and generally decreasing subsidence was observed in Nyamuragira’s NE flow field, and was attributed to post-emplacement cooling and densification of pre- 1997 lavas and associated substrate relaxation due to lava loading. Localised inflation and deflation signals were observed on Nyamuragira’s NE flanks and summit caldera, and were interpreted as reflecting the dynamics of shallow magma systems. Maximum deformation rates within Nyamuragira’s summit caldera were about five times greater than those recorded for the NE flanks. Inflation of Nyamuragira’s NW flanks was interpreted as being due to magma accumulation prior to the 2002 eruption.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available