24 research outputs found
Estimating the frequency of volcanic ash clouds over northern Europe
Fine ash produced during explosive volcanic eruptions can be dispersed over a vast area, where it poses a threat to aviation, human health and infrastructure. Here, we focus on northern Europe, which lies in the principal transport direction for volcanic ash from Iceland, one of the most active volcanic regions in the world. We interrogate existing and newly produced geological and written records of past ash fallout over northern Europe in the last 1000 years and estimate the mean return (repose) interval of a volcanic ash cloud over the region to be 44 ± 7 years. We compare tephra records from mainland northern Europe, Great Britain, Ireland and the Faroe Islands, with records of proximal Icelandic volcanism and suggest that an Icelandic eruption with a Volcanic Explosivity Index rating (VEI) ≥ 4 and a silicic magma composition presents the greatest risk of producing volcanic ash that can reach northern Europe. None of the ash clouds in the European record which have a known source eruption are linked to a source eruption with VEI < 4. Our results suggest that ash clouds are more common over northern Europe than previously proposed and indicate the continued threat of ash deposition across northern Europe from eruptions of both Icelandic and North American volcanoes
Book Reviews : de Saez, Eileen Elliott Marketing concepts for libraries and information services. 1993, London: Library Association Publishing, 160pp, £25 (£20 to LA members), ISBN 0 85157 448 3
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Observations of the plume generated by the December 2005 oil depot explosions and prolonged fire at Buncefield (Hertfordshire, UK) and associated atmospheric changes
The explosions and subsequent fire at the Buncefield oil depot in December 2005 afforded a rare opportunity to study the atmospheric consequences of a major oil fire at close range, using ground-based remote-sensing instruments. Near-source measurements (less than 10km) suggest that plume particles were approximately 50% black carbon (BC) with refractive index 1.73-0.42i, effective radius (Reff) 0.45-0.85μm and mass loading approximately 2000μgm-3. About 50km downwind, particles were approximately 60-75% BC with refractive index between 1.80-0.52i and 1.89-0.69i, R eff∼1.0μm and mass loadings 320-780μgm-3. Number distributions were almost all monomodal with peak at r<0.1μm. Near-source UV spectroscopy revealed elevated trace gas concentrations of SO2 (70ppbv), NO2 (140ppbv), HONO (20ppbv), HCHO (160ppbv) and CS 2 (40ppbv). Our measurements are consistent with others of the Buncefield plume, and with studies of the 1991 Kuwaiti oil-fire plumes; differences from the latter reflecting in part contrasts in combustion efficiency and source composition (refined fuels versus crude oils) leading to important potential differences in atmospheric impacts. Other measurements made as the plume passed overhead approximately 50km downwind showed a reduced solar flux reaching the surface, but little effect on the atmospheric potential gradient (electric field). The wind speed data from the day of the explosion hint at a possible explosion signature. © 2007 The Royal Society