These pages present some background, details and results of ongoing work on the volcanoes of southern Chile by David Pyle (University of Oxford), Tamsin Mather (University of Oxford) and collaborators from Chile, Belgium and the UK. This work began in 2003, when we made our first scientific visit to Villarrica and Llaima, and has continued since with funding from, among others, the Natural Environment Research Council (UK), the International Association of Volcanology and Chemistry of the Earth’s Interior, the British Council, the Leverhulme Trust and the Royal Society.
Current project: the Tempo of Post-Glacial Volcanism in Southern Chile
Our current project is funded by NERC from 2010 – 2014, and is an extended investigation into the nature, timing and consequences of explosive volcanic activity in the Southern Volcanic Zone of Chile, with a focus on the volcanic activity since the peak of the last glaciation (roughly the past 20,000 years); and on the region from about 38 to 41 degrees South (roughly from Llaima to Osorno). This work is a large-scale collaborative effort, and many people have been, or continue to be, involved with aspects of this project. Our primary collaborator in Chile is Jose Antonio Naranjo, of the Chilean Geological Survey (SERNAGEOMIN). Jose has done much of the formative work on the young tephra deposits of this region of Chile, working closely with Hugo Moreno Roa and other colleagues. Outside Chile, we are collaborating with a team at the University of Ghent led by Marc de Batist, who have collected lake cores from many of the larger lakes of southern Chile, and who have been very happy to allow us to sample the volcanic ash layers from their cores. In Oxford, the team include Karen Fontijn, who is a Post-Doctoral Researcher funded on the grant, and also an associate researcher at the University of Ghent; and two PhD students, Harriet Rawson, who is focussing on Mocho Choshuenco volcano; and Stefan Lachowycz, who is working both on Sollipulli volcano, and on the tephra records of the southernmost part of the Southern Volcanic Zone, and the Austral Volcanic Zone. The current work developed out of the NERC-funded PhD work by Sebastian Watt (now a lecturer at the University of Birmingham) in southern Chile, which also involved a team including Tamsin Mather and Jose Naranjo. This work established a tephra-stratigraphy for a part of the volcanic arc between about 41 and 43 degrees South (Watt et al., 2011); a region which became the focus of quite a lot of interest following the eruption of Chaiten volcano in 2008.
Project Rationale: How does volcanic activity respond to changing climate?
There is a growing body of evidence for the coupling of volcanic activity with the climatic system on a range of timescales (e.g. Rampino et al., 1979; Jull and McKenzie, 1996; Jellinek et al., 2004; Mason et al., 2004; Sigmudsson et al., 2010). Theoretical work suggests that glacial cycles may ‘pace’ volcanic activity, modulate eruption style and influence rates of melt production, storage and eruption (e.g. Huybers and Langmuir, 2009; Sigmundsson et al., 2010). Recent work, brought into focus by Huybers and Langmuir (2009), develops the hypothesis that the end of the Last Glaciation was followed by a dramatic pulse of volcanic activity in regions that had once been glaciated. But the field evidence for this pulse of activity is weak. Other than in Iceland (e.g. Sigmundsson et al; 2010) and Europe (Nowell et al., 2006), few places have been investigated sufficiently carefully to see whether this effect is real, or not. Huybers and Langmuir (2009) proposed that degassing of volcanic CO2 as a consequence of a post-glacial pulse in volcanic activity may have helped to accelerate warming globally, at the end of the Late Glacial. But this argument is problematic, since the ‘pulse’ in volcanic activity peaks at ca. 8 – 13 ka; at least 6,000 years after the onset of northern Hemisphere deglaciation (Clark et al., 2009). An alternative explanation is that the pulse is in part an artefact, due the absence of reliable data on eruption rates over the past 20 ka. One reason why the response of volcanic activity to deglaciation is not well understood is because of an absence of evidence from regional-scale studies of post-glacial volcanism. To fill this gap, we propose to reconstruct the post-glacial volcanic history of the southern Chilean volcanic arc, from 38 – 42 degrees S, by integrating archives of eruptions (tephra) and climate from lake core sediments with information from the deposits of major explosive volcanic eruptions from other geological contexts across the region, in order to determine the volcanic response to deglaciation in southern Chile.
We shall address the question of how has volcanic activity along the southern Andean volcanic zone has changed during post-glacial times, through the systematic investigations of tephra (volcanic ash) samples preserved in soils, lakes and peat bogs from sites both close to and distant from the active volcanoes. Our overall aim is to quantify the rates and sizes of volcanic eruptions for this region over the past 18 ka.
The specific objectives of this work are:
A) To characterise the tephra from a number of southern Chilean lakes including Villarrica, Riñihue and Calafquén, among others.
B) To assign analysed tephra layers to source volcanoes, based on fingerprinting of their composition, mineralogy and location;
C) To correlate tephra from core to core, and to develop a tephra-stratigraphic framework for the region extending from 38 – 42 degrees S.
D) To link this framework with the eruption histories of major volcanoes of the region, including Llaima, Villarrica, Sollipulli, Mocho-Choshuenco and Puyhehue, and develop an age model for the regional volcanism of the past 18 ka;
E) To develop isopach maps and estimate eruption size for selected deposits; and to use these data to estimate eruption rates and eruptive fluxes for the region over the past 18 ka;
F) To integrate the new data on volcanic records of the region with evidence, from the same cores, for the timing of climatic changes and large earthquakes over the same period.
Project bibliography (Papers published to date)
Bertrand, S. et al. 2008a. Tephrostratigraphy of late glacial and Holocene sediments of Puyehue Quat. Res. 70:343;
Bertrand, S. et al. 2008b. Climate variability of southern Chile since the Last Glacial Maximum: a continuous sedimentological record from Lago Puyehue (40 S). J Paleolimnol 39:179;
Charlet, F. et al. 2008. Seismic stratigraphy of Lago Puyehue (Chilean Lake District): new views on its deglacial and Holocene evolution. J Paleolimnol 39: 163-177.
Clark, PU et al. 2009. The Last Glacial Maximum. SCIENCE 325:710-714
De Batist, M et al. 2008. A 17,900-year multi-proxy lacustrine record of Lago Puyehue (Chilean Lake District): introduction. J Paleolimnol 39:151-161.
Gilbert, JS et al. 1996. Non-explosive, constructional evolution of the ice-filled caldera at Volcan Sollipulli, Chile. Bull Volc 58: 67-83
Glasser, N.F., et al. The glacial geomorphology and Pleistocene history of South America… Quat Sci Rev 27:365-390, 2008.
Huesser, CJ, 2003. Ice Age Southern Andes: a chronicle of paleoecological events. Developments in Quaternary Science, 3, 240 pp.
Huybers, P. & C. Langmuir. Feedback between deglaciation, volcanism and atmospheric CO2. Earth. Plan. Sci. Lett. 286, 479-491, 2009.
Jellinek, A.M., M. Manga, M.O. Saar. Did melting glaciers cause volcanic eruptions in eastern California?… J. Geophys. Res. 109:B09206, 2004.
Jull, M., D. McKenzie. The effect of deglaciation on mantle melting beneath Iceland. J. Geophys. Res. 101:21815-21828, 1996.
Juvigne, E et al 2008. Tephrostratigraphy of lake sediments located in an active geodynamic setting: lessons from lake Icalma (Chile, southern volcanic zone, 38 S). Quaternaire 19:175-189.
Mason, BG et al. 2004, Seasonality of volcanic eruptions, Journal of Geophysical Research 109, B04206
Moernaut, J et al. 2009. Fluidization of buried mass-wasting deposits in lake sediments and its relevance for paleoseismology: Results from a reflection seismic study of lakes Villarrica and Calafquen (South-Central Chile). Sed Geol 213: 121-135.
Naranjo JA, Moreno H, 1991. Actividad explosiva postglacial en el volcan Llaima, Andes del Sur (38° 45′ S). Rev Geol Chile, 18: 69-80
Naranjo, J.A. & C.R. Stern 2004. Holocene tephrochronology of the southernmost part of the Andean Southern Volcanic Zone. Rev. Geo. Chile 31, 224-240.
Naranjo, JA & CR Stern, 1998, Holocene explosive activity of Hudson Volcano, southern Andes. Bull Volcanol 59: 291-306
Naranjo, JA et al.,1993, Volcanismo explosivo reciente en la caldera del volcán Sollipulli, Andes del Sur (39°S). Rev Geol Chile, 20: 167-191.
Nowell, DAG et al. 2006, Episodic Quaternary Volcanism in France and Germany. J Quat Sci 21, 645-675 Pagli,C., F.
Rampino, M.R et al., 1979. Can rapid climatic change cause volcanic eruptions? Science, 206:826-829.
Sigmundsson, F et al., 2010. Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from Iceland. Phil Trans Royal Soc London A368: 2519-2534
Stern, CR, 2008. Holocene tephrochronology record of large explosive eruptions in the southernmost Patagonian Andes. Bull Volcanol 70, 435-454.
Watt SFL et al. 2011, Holocene tephrochronology of the Hualaihue region (Andean southern volcanic zone, ~ 42 S), southern Chile. Quaternary International (INTREPID volume), 246, 324-343.
Watt SFL et al. 2013, The volcanic response to deglaciation: evidence from glaciated arcs and a reassessment of global eruption records, Earth-Science Reviews 122, 77-102.
Whitlock, C et al., 2006, Postglacial vegetation, climate, and fire history along the east side of the Andes (lat 41–42.5°S), Argentina, Quaternary Research 66, 187-201.
Links to general information on the volcanoes of Chile
Chilean Volcano Monitoring Network (SERNAGEOMIN) Lists the current status of many of Chile’s active volcanoes