Prolonged and heavy exposure to particles of respirable, crystalline silica-rich volcanic ash could potentially cause chronic, fibrotic disease, such as silicosis, in individuals living in areas of frequent ash fall. Here, we show that the rhyolitic ash erupted from Chaitén volcano, Chile, in its dome-forming phase, contains increased levels of the silica polymorph cristobalite, compared to its initial plinian eruption. Ash erupted during the initial, explosive phase (2–5 May 2008) contained approximately 2 wt.% cristobalite, whereas ash generated after dome growth began (from 21 May 2008) contains 13–19 wt.%. The work suggests that active obsidian domes crystallise substantial quantities of cristobalite on time-scales of days to months, probably through vapour-phase crystallisation on the walls of degassing pathways, rather than through spherulitic growth in glassy obsidian. The ash is fine-grained (9.7–17.7 vol.% <4 µm in diameter, the respirable range) and the particles are mostly angular. Sparse, fibre-like particles were confirmed to be feldspar or glass.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Baxter PJ, Bonadonna C, Dupree R, Hards VL, Kohn SC, Murphy MD, Nichols A, Nicholson RA, Norton G, Searl A, Sparks RSJ, Vickers BP (1999) Cristobalite in volcanic ash of the Soufriere Hills Volcano, Montserrat, British West Indies. Science 283:1142–1145
Getahun A, Reed MH, Symonds R (1996) Mount St. Augustine volcano fumarole wall rock alteration: mineralogy, zoning, composition and numerical models of its formation process. J Volcanol Geotherm Res 71:73–107
Hincks TK, Aspinall WP, Baxter PJ, Searl A, Sparks RSJ, Woo G (2006) Long term exposure to respirable volcanic ash on Montserrat: a time series simulation. Bull Volcanol 68:266–284
Horwell CJ (2007) Grain size analysis of volcanic ash for the rapid assessment of respiratory health hazard. J Environ Monit 9:1107–1115
Horwell CJ, Baxter PJ (2006) The respiratory health hazards of volcanic ash: a review for volcanic risk mitigation. Bull Volcanol 69:1–24
Horwell CJ, Sparks RSJ, Brewer TS, Llewellin EW, Williamson BJ (2003) The characterisation of respirable volcanic ash from the Soufriere Hills Volcano, Montserrat, with implications for health hazard. Bull Volcanol 65:346–362
Le Blond JS, Cressey G, Horwell CJ, Williamson BJ (2009) A rapid method for quantifying single mineral phases in heterogeneous natural dust using X-ray diffraction. Powd Diffr 24:17–23
Naranjo JA, Stern CR (2004) Holocene tephrochronology of the southernmost part (42°30′-45°S) of the Andean Southern Volcanic Zone. Rev Geol Chile 31:225–240
Reich M, Zúñiga A, Amigo A, Vargas G, Morata D, Palacios C, Parada MA, Garreaud RD (2009) Formation of cristobalite nanofibers during explosive volcanic eruptions. Geology 37:435–438
Swanson SE, Naney MT, Westrich HR, Eichelberger JC (1989) Crystallization history of Obsidian Dome, Inyo Domes, California. Bull Volcanol 51:161–176
Watkins J, Manga M, Huber C, Martin M (2009) Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles. Contrib Mineral Petrol 157:163–172
World Health Organisation (1986) Asbestos and other natural mineral fibres: environmental health criteria 53. World Health Organisation, Geneva
Zoltai T (1981) Amphibole asbestos mineralogy. Mineral Soc Am Rev Mineralogy 9A:237–278
Thanks to Chris Rolfe, University of Cambridge, UK for grain size analyses and Nick Marsh, University of Leicester, UK for XRF analyses. Thanks to all those who were kind enough to supply fresh ash samples so rapidly following eruption. We are grateful to Luis Lara for advice on the Chaitén dome obsidian. Horwell acknowledges a Natural Environment Research Council (NERC) Urgency Grant NE/G001561/1 and a NERC Post-doctoral Fellowship NE/C518081/2. JSL's work is funded by an NERC studentship NER/S/A/2006/14107. Particular thanks to P. Baxter, A. Bernard, G. Plumlee and S. Hillier for useful reviews of the paper before and after submission.
Editorial responsibility: P. Delmelle
Electronic Supplementary Materials
Below is the link to the electronic supplementary material.
(DOC 49.5 kb)
About this article
Cite this article
Horwell, C.J., Le Blond, J.S., Michnowicz, S.A.K. et al. Cristobalite in a rhyolitic lava dome: evolution of ash hazard. Bull Volcanol 72, 249–253 (2010). https://doi.org/10.1007/s00445-009-0327-1