HR: 0830h
AN: V11C-0518    [PDF]
TI: SO$_{2}$ loss rates at Lascar volcano, Chile: preliminary results and interpretations from 2002 measurements
AU: * Rodriguez, L A
EM: larodrig@mtu.edu
AF: Geological and Mining Engineering & Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Watson, I
EM: watson@mtu.edu
AF: Geological and Mining Engineering & Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Tassi, F
EM: francot@steno.geo.unifi.it
AF: Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, Via la Pira 4, Firenze, 50121 Italy
AU: Viramonte, J
EM: viramont@unsa.edu.ar
AF: Instituto GEONORTE, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Buenos Aires 177, Salta, 4400 Argentina
AU: Poodts, M
EM: marpoodts@yahoo.com.ar
AF: Instituto GEONORTE, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Buenos Aires 177, Salta, 4400 Argentina
AU: Rose, W I
EM: raman@mtu.edu
AF: Geological and Mining Engineering & Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Bluth, G J
EM: gbluth@mtu.edu
AF: Geological and Mining Engineering & Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AB: The measurement of volcanic SO$_{2}$ emission rates is commonly performed on cross sections of the plume some distance downwind from the active vent, some time after its interaction with other volcanogenic gases (primarily water), particles and droplets of volcanogenic and/or meteoric origin, and atmospheric gases. The emission rates being measured therefore do not necessarily represent the real fluxes emitted by the volcano; instead they are underestimated due to the conversion of SO$_{2}$ to SO$_{4}$$^{-2}$ (Oppenheimer et al., 1998). Near source plume chemistry is not well understood, but can have significant effects on climatologically active species, which is why it is important to quantify volcanic SO$_{2}$ conversion rates as a function of meteorological environment and plume age. A mini-UV spectrometer and a Microtops II sun photometer were used to measure SO$_{2}$ emission rates and aerosol particle size distributions at Lascar volcano, Central Andes, during the months of October and November 2002. Direct gas measurements from fumaroles in the crater were made on November 1. These represent the first gas samples ever collected directly in the crater. Lascar volcano represents one of the end-members of the environmental spectrum, being a high volcano (summit altitude at $>$5600 meters above sea level) in a dry atmosphere (average RH$<$15$%$). Its location allows for simultaneous near-vent and downwind measurements at similar altitudes. Here we present our preliminary results from November 2, 2002, taken at a variety of azimuthal angles (effective distances from the plume) from the vent downwind to about 20 km, during a two-hour period (0900-1100 local time). This represents a time downwind of up to $\sim$42 minutes, based on a plume speed of $\sim$8 m/sec. Initial interpretations and correlations with the direct measurements are also presented. The data obtained from a Kestrel 4000 weather station will help clarify the effects of Lascar's high, dry, and extremely transmissive atmosphere upon SO$_{2}$ conversion rates.
DE: 0370 Volcanic effects (8409)
DE: 3360 Remote sensing
DE: 8409 Atmospheric effects (0370)
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting