NCEO:Theme 6

COMET+

National Centre for Earth Observation: Theme 6
Investigators
Co-Investigator	Dr Don Grainger University of Oxford
Recognised Researcher	Dr Elisa Carboni University of Oxford
Funding Agency
NERC
Project start	1 April 2008
Project finish	30 March 2013

National Centre for Earth Observation: Theme 6

NCEO: Theme 6 is a component of the National Centre for Earth Observation funded by NERC.

The aim of this sub-theme is to use EO data to measure global and regional budgets of volcanic emissions, particularly of SO2, and to integrate these measurements with regional- to local-scale measurements of volcanic emissions, ground deformation, and seismicity, to improve mathematical models for the mechanics of volcanic systems.

Volcanic SO2 is a key gas species for the planet’s radiative balance and atmospheric composition (Graf et al., 1997; Robock, 2000; Grainger and Highwood, 2003; Millard et al., 2006), and, in combination with other species, for understanding magmatic processes. Volcanic SO2 is also a significant component of the stratospheric S budget (Pyle et al., 1996), however volcanic SO2 release to the atmosphere is both uncertain and variable (7–11 Tg S yr-1, Mather et al., 2003) and individual volcanic emissions can cause large local and regional perturbations. Recent developments in satellite-borne remote sensing of volcanic gases and particles allow us, for the first time, to detect and measure volcanic emissions on a global scale in near-real time. These advances will enable us to investigate the controls on these fluxes, and to understand their consequences for the Earth’s surface and atmosphere.

The processes of magma ascent and eruption depend strongly upon the evolution of the magma’s physical properties as it partitions into melt, crystals and gas during ascent, upon the mechanical interactions between magma and its surrounding rock, which determine the magma’s pathways through the crust, and upon the local stress regime. We plan observations on a hierarchy of scales from the global to the regional down to the individual volcano, to address different aspects of volcanic systems.

Volcanoes generate readily measurable ground deformation in response to influx and efflux of magma and gases. One strand of this sub-theme (§4.2.3) is to relate detailed quantitative budgets of the fluxes of erupted gas, lava, and tephra to the ground deformation at selected volcanoes in order to constrain physical models of the volcanic processes. It has recently been shown, however, that external forcings (the hydrological cycle; large earthquakes) influence volcanic activity on a range of spatial and temporal scales (Neuberg, 2000; Mason et al., 2004; Manga and Brodsky, 2006), suggesting that magmatic systems may be sensitive to small stress changes organized on a scale much larger than that of an individual volcano. For this reason, we shall combine measurements of gas emissions and ground deformation on the largest scales that are practicable, to test hypotheses about external forcings of volcanic arcs. Rift zones are the only examples accessible to direct observation of the major means of delivery of magma to the earth’s surface (most of which takes place at the oceanic ridges), and we shall undertake regional scale deformation studies of selected rift systems in order to constrain the kinematics and dynamics of such zones (§4.2.2).