Nature 376, 675 - 678 (24 August 2002); doi:10.1038/376675a0

Forest-killing diffuse CO₂ emission at Mammoth Mountain as a sign of magmatic unrest

C. D. Farrar^*, M. L. Sorey^†, W. C. Evans^†, J. F. Howle^*, B. D. Kerr^‡, B. M. Kennedy^§, C.-Y. King^† & J. R. Southon

^*US Geological Survey, Carnelian Bay, California 96140, USA
^†US Geological Survey, Menlo Park, California 94025, USA
^‡US Geological Survey, Sacramento, California 95825, USA
^§Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
Lawrence Livermore National Laboratory, Livermore, California 94551, USA

MAMMOTH Mountain, in the western United States, is a large dacitic volcano with a long history of vo lean ism that began 200 kyr ago¹ and produced phreatic eruptions as recently as 500 200 yr BP (ref. 2). Seismicity, ground deformation and changes in fumarole gas composition suggested an episode of shallow dyke intrusion in 1989–90 (refs 3, 4). Areas of dying forest and incidents of near asphyxia in confined spaces, first reported in 1990, prompted us to search for diffuse flank emissions of magmatic CO₂, as have been described at Mount Etna⁵ and Vulcano⁶. Here we report the results of a soil-gas survey, begun in 1994, that revealed CO₂ concentrations of 30–96% in a 30-hectare region of killed trees, from which we estimate a total CO₂ flux of 1,200 tonnes per day. The forest die-off is the most conspicuous surface manifestation of magmatic processes at Mammoth Mountain, which hosts only weak fumarolic vents and no summit activity. Although the onset of tree kill coincided with the episode of shallow dyke intrusion, the magnitude and duration of the CO₂ flux indicates that a larger, deeper magma source and/or a large reservoir of high-pressure gas is being tapped.

References

1.	Bailey, R. A. Map I-1933 (US Geol. Surv., 1989).
2.	Miller, C. D. Geology 13, 14−17 (1985). | Article |
3.	Sorey, M. L., Kennedy, B. M., Evans, W. C., Farrar, C. D. & Suemnicht, G. A. J. geophys. Res. 98, 15871−15889 (1993).
4.	Hill, D. P. et al. Bull. seism. Soc. Am. 80, 325−339 (1990).
5.	Allard, P. et al. Nature 351, 387−391 (1991). | Article | ISI | ChemPort |
6.	Baubron, J. C., Allard, P. & Toutain, J. P. Nature 344, 51−53 (1990). | ChemPort |
7.	Drew, M. C. in Plant Life under Oxygen Deprivation (eds Jackson, M. B., Davies, D. D. & Lambers, H.) Ch. 20 (SPB Academic, The Hague, 1991).
8.	Qi, J., Marshall, J. D. & Mattson, K. G. New Phytol. 128, 435−441 (1994).
9.	Joseph, E. J. (ed.) Chemical Safety Data Guide (Bureau National Affairs, Washington DC, 1985).
10.	Solomon, D. K. & Cerling, T. E. Wat. Resour. Res. 23, 2257−2265 (1987). | ChemPort |
11.	Cerling, T. E., Solomon, K. D., Quade, J. & Bowman, J. R. Geochim. cosmochim. Acta 55, 3403−3405 (1991). | Article | ChemPort |
12.	Aravena, R., Schiff, S. L., Trumbore, S. E., Dillon, P. J. & Elgood, R. Radiocarbon 34, 636−645 (1992). | ISI | ChemPort |
13.	Barberi, F. & Carapezza, M. L. Bull volcan. 56, 335−342 (1994).
14.	Symonds, R. B., Reed, M. H. & Rose, W. I. Geochim. cosmochim. Acta 56, 633−657 (1992). | Article | ISI | ChemPort |
15.	Casadevall, T. J. et al. Science 221, 1383−1385 (1983). | ChemPort |
16.	Harris, D. M., Sato, M., Casadevall, T. J., Rose, W. I. Jr & Bornhorst, T. J. Prof. Pap. U.S. geol. Surv. 1250, 201−207 (1981). | ChemPort |
17.	Gerlach, T. M. EOS 72, 249−255 (1991).
18.	Gerlach, T. M. & Graeber, E. J. Nature 313, 273−277 (1985). | Article | ISI | ChemPort |
19.	Bottinga, Y. & Javoy, M. Earth planet. Sci. Lett. 95, 215−225 (1989). | Article | ChemPort |
20.	Langbein, J., Hill, D. P., Parker, T. N. & Wilkinson, S. K. J. geophys. Res. 98, 15851−15870 (1993). | ISI |
21.	Pitt, A. M. & Hill, D. P. Geophys. Res. Lett. 21, 1679−1682 (1994). | Article |
22.	Sanders, C. O., Ponko, S. C., Nixon, L. D. & Schwartz, E. A. J. geophys. Res. 100, 8311−8326 (1995). | Article |
23.	Hill, D. P., Bailey, R. A. & Ryall, A. S. J. geophys. Res. 90, 11111−11120 (1985).
24.	Bailey, R. A. & Hill, D. P. Geosci. Canada 17, 175−179 (1990).