HR: 17:00h
AN: V24A-05    [Abstracts]
TI: Thermal Monitoring at Volcán de Colima, Mexico: Characterizing the Activity and Studying the Transition Between Explosive and Effusive Regimes
AU: * Varley, N R
EM: nick@ucol.mx
AF: Facultad de Ciencias, Universidad de Colima, Av. 25 de Julio #965, Colima, COL 28045 Mexico
AU: Johnson, J
EM: jeff.johnson@unh.edu
AF: Department of Earth Sciences, University of New Hampshire, 56 College Road, Durham, NH 03824 United States
AB: Volcán de Colima has significantly increased in its activity during the last few years. Explosive activity during 2005 produced pyroclastic flows which reached up to 5.44 km, distances which not been recorded since the last Plinian eruption (1913). Monitoring is being improved by the introduction of thermal, infrasound and scanning UV spectrometer systems. Seismic monitoring has been enhanced by the use of pattern recognition techniques for rapid evaluation. The techniques are being utilized to characterize and quantify both explosive and effusive activity to enable improved modelling and understand the transition between styles. Thermal imaging using an infrared camera has enabled the temporal variation in fumarole temperature to be monitored remotely. Precursory activity has been identified prior to large explosive events: swarms of low frequency (< 10 Hz) seismic events and an increase in fumarole temperatures. The distribution of the seismic events has been analysed, showing the relationship between the swarm and the magnitude of the associated explosion. Increasing temperatures reflect the uprising of the magma body and pressurization within the conduit. Explosive activity has been examined in detail, comparing the thermal characteristics of the plume with its ascent rate, gas flux, ash content and associated seismicity. The thermal evolution of some of the larger events was captured with an installed sensor. The arrival of the relatively cool pyroclastic flows was also registered. A poor correlation has been observed between certain variables, which has important implications for both numeric modelling of this type of activity and for monitoring, where seismic amplitudes are often used to quantify explosive events. Thermal monitoring during episodes of effusion enables the study of the evolution of the dome and flows, which can assist in the forecasting of collapse events. It is clear that the integration of thermal monitoring with various other geophysical tools allows more precise models to be created and thus better forecasting of upcoming activity.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8425 Effusive volcanism
DE: 8428 Explosive volcanism
DE: 8430 Volcanic gases
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005