1. Rapid response to the Chaiten eruption, Chile, May 2008: ash fallout and impact David Pyle University of Oxford Work funded by a NERC Urgency Grant Collaborators: Sebastian Watt, Tamsin Mather, Naomi Matthews, Blae Quayle, Elspeth Robertson (Oxford); Robert Martin (Cambridge); Costanza Bonadonna (Geneva); Chuck Connor, Alain Volentik (Florida) Thanks to: Alberto Fierro, British Embassy, Buenos Aires; the Mayor of Esquel, Chubut Province; Gustavo Villarosa, Univ. Bariloche. Talk given to the UK National Centre for Earth Observation Science Meeting, September 2009 Photo: Puntiagudo volcano (left) and Osorno volcano (right), southern Chile. David PylePhoto: Chaiten Dome, January 2009. David Pyle

2. Ash dispersal in volcanic eruptions How is ash transported during explosive volcanic eruptions? What is the fate of ash once deposited? How good are current models of ash transport and deposition? Can Earth Observation tools provide a rapid impact assessment following explosive eruptions? Photo: NASA MODIS infra red, May 5 2008

3. Regional context: volcanism in Southern Chile Active volcanic arc (~ 1 volcano every 35 km); multiple eruptions over past 10,000 yr Images: Sebastian Watt; work described in SFL Watt et al, Holocene tephrochronology of the Hualaihue region, Andean southern volcanic zone, southern Chile. Quaternary International (2011, 246, p 324; http://dx.doi.org/10.1016/j.quaint.2011.05.029a) and SFL Watt, PhD thesis, University of Oxford, 2010. http://dx.doi.org/10.1016/j.quaint.2011.05.029a

4. Regional context: volcanism in Southern Chile Location, structure and stability of edifices controlled by regional tectonics SFL Watt et al 2009 Bulletin of Volcanology 71, 559-574

5. Regional context: volcanism in Southern Chile Eruptions often triggered by major regional earthquakes SFL Watt et al 2009 Earth and Planetary Science Letters 277, 399-407

6. Chaiten eruption: May 2008 2008: limited precursory seismicity at a volcano with no known eruptions in ca. 10 kyr Images: Sebastian Watt, unpublished. Central image – earthquake search from NEIC.

7. Chaiten eruption: the ash plume crosses Patagonia May 3, 2008. (MODIS). May 5, 2008. (MODIS). Terra MODIS (15:15 UT, 6 May) 6 May eruption column; Aqua MODIS (19:15 UT, 6 May) Satellite images: NASA MODIS Rapid Response Team SFL Watt et al., Journal of Geophysical Research 114, B04207, 28 April 2009. S Carn et al., EOS Trans AGU, 90 (24), 205-7, 16 June 2009.

8. Satellite imagery records widespread ash fallout across central Patagonia SFL Watt et al., Journal of Geophysical Research 114, B04207, 28 April 2009

9. Chaiten eruption: May 2008 Still cleaning up ash, Futaleufu (January 2009) Lahar damage in Chaiten town, January 2009 Photo: David Pyle

10. Fieldwork in June 2008 by Seb Watt, Rob Martin and Naomi Matthews Chaiten eruption: May 2008 Urgency fieldwork: rapid mapping of ash thickness, grainsize at 250 sites. Area with > 0.1 mm ash ~ 8 x the area of Wales Erupted volume ~ 0.07 km 3 : largest explosive eruption of rhyolite since Katmai (1912).

11. Thick fallout deposits near Chaiten volcano (January 2009) reveal eruption stratigraphy Reworking and continuing activity Main ash fallout phase: May 6-8? Ash fallout: May 3-5? May 2 – initial phase Tracking ash deposit preservation: Argentinian lakes and Chilean grasslands (January 2009) Photos: David Pyle

12. Field data: new constraints for ash dispersal models; ground-truthing satellite observations Proximal stratigraphy preserved on a tree stump near Minchinmavida. Photos: David Pyle F. Alfano et al., Tephra stratigraphy and eruptive volume of the May 2008 Chaiten eruption, Chile. Bulletin of Volcanology (2011, 73, p 613 http://dx.doi.org/10.1007/s00445-010-0428-x) Ash fallout across the snow and ice cap of Minchinmavida. Image from Jan 2009

13. Chaiten eruption: immediate environmental impact? RS Martin et al 2009 Journal of Volcanology and Geothermal Research 184, 462-472.

14. Ephemeral lake waters Wild grasses RS Martin et al., Journal of Volcanology and Geothermal Research 184, 462-472, 20 July 2009. Chaiten eruption: immediate environmental impact? Correlations of trace element concentrations with ash fallout thickness across central Patagonia (June 2008)

15. Chaiten eruption: short lived regional environmental impact Comparison of grasses in June 2008, and January 2009 RS Martin et al., Journal of Volcanology and Geothermal Research 184, 462-472, 20 July 2009.

16. Chaiten eruption, 2008 -Once in a decade opportunity to capture details of fresh ash fallout across a continent - Significant new dataset against which to test and refine ash transport and deposition models - Case study of a major eruption at a long-dormant volcano in an understudied part of the world Chaiten Dome, January 2009. Photo: David Pyle