HR: 11:20h
AN: V12B-05    [Abstracts]
TI: Quantification of the Gas Mass Emitted During a Single Explosion on Stromboli with the SO2 Camera
AU: * Mori, T
EM: mori@eqchem.s.u-tokyo.ac.jp
AF: Laboratory for Earthquake Chemistry, Graduate School of Science, University of Tokyo, 7-3- 1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
AU: Burton, M
EM: burton@ct.ingv.it
AF: Instituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, 95123, Italy
AU: Wright, T E
EM: tew24@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom
AB: The recent development of the SO₂ camera is a powerful new tool for volcanologists that allows quantitative imaging of SO₂ amounts within volcanic plumes. Such SO₂ images are information-rich compared to traditional measurements by COSPEC or compact UV spectrometer systems which measure the equivalent of one pixel in an SO₂ image. Furthermore, using time-series of SO₂ images, we can examine short- lived events on the order of seconds and quantitatively constrain wind speed, the greatest source of error in flux determination. The new capabilities offered by the SO₂ camera herald a major step forward for understanding degassing processes and therefore civil defence. On October 3 and 4, 2006, we performed SO₂ imaging measurements at Stromboli volcano, Italy. The SO₂ camera was placed on the north-eastern flank of the volcano about 2.4 km from the summit craters and recorded SO₂ images with a time-interval of 5.0 seconds on Oct. 3 and 3.2 seconds on Oct. 4, respectively. More than 1500 SO₂ plume images were collected. Major variations in SO₂ flux were observed over a timescale of a few minutes and several peaks were seen. By relating the major increases of the flux with a movie of the SO₂ plume images, we can conclude that the main cause of these variations was strombolian explosions. In the afternoon of Oct. 3, we took the SO₂ camera to the summit of the volcano. The aim of the measurements was to quantify the amount of SO₂ emitted during a single explosion. The SO₂ camera was set up 400 m north of the craters and a single UV band-pass filter (Center wavelength: 310 nm, HWHM 10 nm) was used in the measurements. We obtained more than 600 plume images with time interval between frames of ~2 seconds. By analyzing the SO₂ images, we could separate several explosive events from the background quiescent degassing. The amount of SO₂ emitted by a single explosion was 15 - 40 kg which corresponds to approximate total gas mass of 350 - 900 kg. Assuming that the gas slug originated from ~75 MPa (as demonstrated by recent FTIR measurements on Stromboli) we may calculate the volume of the slug at that pressure. Using the ideal gas law and assuming a spherical bubble in the conduit, at a pressure of 75 MPa and temperature of 1150°, this gas amount will occupy a sphere with radius 0.8 - 1.1 m.
DE: 8419 Volcano monitoring (7280)
DE: 8430 Volcanic gases
DE: 8485 Remote sensing of volcanoes
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting