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Llaima update, 7 December 2009 7 December 2009

Posted by admin in activity reports, Chile, Llaima.
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Some more information on activity at Llaima volcano in Chile, which is currently on Yellow Alert.

Chilean state emergencies office ONEMI has issued a new bulletin, reporting that ‘a seismic swarm associated with internal degasification’ and marked by ‘increased release of the volcano’s internal energy’ was detected at Llaima between 16:00 and 18:00 local time on 6 December. Fumarolic activity has been continuing, and the main crater remains obstructed. ONEMI is maintaining Yellow Alert for Llaima and surrounding communities, and the 4-kilometre radius exclusion zone remains in force.

Llaima volcano, 18 November 2009 (OVDAS-SERNAGEOMIN)
Above: Webcam image of Llaima volcano viewed from Cherquenco on 18 November 2009 (OVDAS-SERNAGEOMIN). [source]

The state geological service SERNAGEOMIN have also published a new Llaima bulletin on their web site today, which notes that fumarolic activity and volcanic gas emissions were observed during the period 14 November to 1 December when weather permitted, and contains the following information about recent changes in the volcano’s seismic activity:

Regarding the seismicity associated with Llaima volcano, it has been marked by the occurrence of a new type of LP [long period] event, of low frequency (less than 3.0 Hz), characterized by a spindle-shaped envelope with a higher amplitude (energy) than the other types of LP seismicity and a duration in some cases of up to 4 minutes. A continuing decline in the numbers of the other three types of LP earthquakes was observed, with an average 5 earthquakes per hour being registered, of which two to three correspond to this new type of event. The background tremor kept its characteristics of amplitude and spectral content.

The foregoing (the changes in the types of seismic events, which appear to be generated by different mechanisms) implies a greater complexity in the internal dynamics of the volcano. In addition, the main crater remains blocked, so the likelihood of a possible volcanic reactivation is greater than in previous months.

Yellow Alert, notes the bulletin, indicates that ‘eruptive activity may occur within weeks or months’.

For all our Llaima coverage: Llaima « The Volcanism Blog.

Information
Global Volcanism Program: Llaima – summary information for Llaima (1507-11=)
Oficina Nacional de Emergencia – Chilean government emergencies office
SERNAGEOMIN – Servicio Nacional de Geología y Minería, Chile
Proyecto Observación Visual Volcán Llaima – Llaima Visual Observation Project

The Volcanism Blog