Magma Ascent and Degassing at Volcán de Colima, Mexico: Monitoring the Increasing Activity
Abstract
Volcán de Colima presents a great opportunity for the study of conduit and plume processes. Since 2001, the volcano has been in almost constant eruption with daily explosive activity and three significant effusive periods occurring since 1998. It is clear that small variations in certain factors, such as the magma ascent rate, temperature or volatile-contents can promote a change in eruption style. During 2005, various rapid switches were observed, with at times simultaneous occurrence of explosions and dome growth at different vents within the crater. The sequence of explosions included the largest observed since the last Plinian event in 1913. The monitoring strategy at Volcán de Colima is being revised as a response to the increase in activity during the last few years, which possibly signifies the start of a pre-Plinian phase. Traditional systems are being supplemented with thermal and infrasound monitoring, which are greatly increasing the data available to study the evolution of activity and facilitate hazard assessment. To highlight the critical parameters, models are required of the magma ascent and degassing processes. Vulcanian explosions from 2005 were characterized by variable ash-content, column ascent velocity and gas emission. The processes are being studied, integrating a variety of data sets. Following an explosion, rapid sealing of the system was often followed by brittle fracturing within the conduit. During subsequent pressurization, seismic swarms were detected as precursory signals to the following explosion. Increased fumarole temperatures have been measured remotely prior to this type of larger magnitude event some minutes or hours prior to their onset. In addition to the precursors, the relationship between different parameters is being studied, including a statistical study of the explosivity, temperature and ascent velocity of the column, and partitioning of acoustic and seismic energy. Resulting models will have an impact for the future monitoring strategy.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2007
- Bibcode:
- 2007AGUSM.V41B..03V
- Keywords:
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- 7280 Volcano seismology (8419);
- 8414 Eruption mechanisms and flow emplacement;
- 8419 Volcano monitoring (7280);
- 8428 Explosive volcanism;
- 8430 Volcanic gases