Georgina M. Sawyer

A total volatile inventory for Masaya Volcano, Nicaragua

NERC project “Magma dynamics at persistently degassing basaltic volcanoes: A novel approach to linking volcanic gases and magmatic volatiles within a physical model” (NE/F004222/1 and NE/F005342/1).

Effects of a volcanic plume on thermal imaging data

Ground-based thermal imaging is becoming an increasingly important tool for volcano surveillance, however the impact of volcanic plumes on quantitative measurements of surface temperature has not been previously evaluated. Here we use a radiative transfer model to simulate gas ( primarily H2O and SO2) and aerosol absorptions over the path between a thermal camera and a heat source on Stromboli volcano, Italy. A FTIR spectrometer was used to quantify path amounts of gases likely to be encountered when making thermal measurements of the active craters. We find that when using a camera sensitive from 7.5 to 13 mu m, underestimates of similar to 400 K may be produced when viewing a source with an actual temperature of 1200 K. Cameras that operate between 3 and 5 mu m are somewhat less susceptible to these errors.

High‐resolution size distributions and emission fluxes of trace elements from Masaya volcano, Nicaragua

Active volcanoes are significant natural sources of trace elements to the atmosphere yet the processes of emission and the impacts of deposition into terrestrial and aquatic environments remain poorly understood. The varying contributions of volatile degassing and magma ejection (i.e., spattering, spraying, extrusion and fragmentation) to the emission of trace elements from Masaya volcano (Nicaragua) are investigated through measurement of high-resolution trace element size distributions using cascade impactors in 2009 and 2010. The volatile elements (e.g., As, Cd, Tl, Cu, Pb, Zn) are strongly correlated across the size distribution and exist in the plume primarily as fine sulfate (0.6 μm diameter) with lesser amounts transported as coarse sulfates (3.5 μm diameter) and coarse chlorides (11 μm diameter). These results suggest that trace elements released from the magma as chlorides react rapidly with H2SO4 in the plume to form sulfates. In contrast, the non-volatile elements (e.g., alkali earth and rare earth) exist primarily as particles in the 1–10 μm range and show no correlation with sulfate, chloride or the volatile elements, suggesting that they are emitted primarily by magma ejection. Trace element emission fluxes from Masaya in 2010 were estimated using filter pack measurements, with emissions of Cu, Zn, As, Tl, Rb and Cd each in excess of 10 kg d−1. These emission fluxes are similar to those measured in 2000–2001 suggesting notable decadal stability in the emission of trace elements from Masaya.

Observations of the plume generated by the December 2005 oil depot explosions and prolonged fire at Buncefield (Hertfordshire, UK) and associated atmospheric changes

The explosions and subsequent fire at the Buncefield oil depot in December 2005 afforded a rare opportunity to study the atmospheric consequences of a major oil fire at close range, using ground-based remote-sensing instruments. Near-source measurements (less than 10 km) suggest that plume particles were approximately 50% black carbon (BC) with refractive index 1.73−0.42i, effective radius (Reff) 0.45–0.85 μm and mass loading approximately 2000 μg m−3. About 50 km downwind, particles were approximately 60–75% BC with refractive index between 1.80−0.52i and 1.89−0.69i, Reff∼1.0 μm and mass loadings 320–780 μg m−3. Number distributions were almost all monomodal with peak at r<0.1 μm. Near-source UV spectroscopy revealed elevated trace gas concentrations of SO2 (70 ppbv), NO2 (140 ppbv), HONO (20 ppbv), HCHO (160 ppbv) and CS2 (40 ppbv). Our measurements are consistent with others of the Buncefield plume, and with studies of the 1991 Kuwaiti oil-fire plumes; differences from the latter reflecting in part contrasts in combustion efficiency and source composition (refined fuels versus crude oils) leading to important potential differences in atmospheric impacts. Other measurements made as the plume passed overhead approximately 50 km downwind showed a reduced solar flux reaching the surface, but little effect on the atmospheric potential gradient (electric field). The wind speed data from the day of the explosion hint at a possible explosion signature.

Modern Multispectral Sensors Help Track Explosive Eruptions

Due to its massive air traffic impact, the 2010 eruption of Eyjafjallajokull was felt by millions of people and cost airlines more than U.S.

Chapter 5: Volcanic Fluorine Emissions: Observations by Fourier Transform Infrared Spectroscopy

1.7 billion. The event has, thus, become widely cited in renewed efforts to improve real-time tracking of volcanic plumes, as witnessed by special sections published last year in Journal of Geophysical Research, (117, issues D20 and B9).

Deep Carbon Emissions from Volcanoes

Volcanoes are an important natural source of fluorine to the environment. For several decades, fluorine emissions from volcanoes have been measured by laboratory analysis of samples collected in situ, and abundances compared with other gas species to infer magmatic and hydrothermal processes occurring at depth. More recently, open-path Fourier transform infrared (OP-FTIR) spectroscopy has been applied to field measurements of volcanic gas plumes, offering several advantages including the ability to detect and quantify simultaneously, and with high time resolution, many volcanic gas species. These include hydrogen fluoride (HF) and silicon tetrafluoride (SiF4), and potentially other F-bearing gases. Such measurements yield valuable insights into the degassing of fluorine from magmas and contribute to our understanding of the environmental impacts of volcanic emissions.