Chaitén and Llaima updates from SERNAGEOMIN 1 September 2009Posted by admin in activity reports, Chaitén, Chile, eruptions, Llaima.
Tags: Chaitén, Chile, Llaima, South America, volcanic activity reports, volcanic eruptions
The Chilean state geological service SERNAGEOMIN has published brief updates on Chaitén and Llaima volcanoes on its website in a combined bulletin dated 31 August 2009. Translation as follows.
SERNAGEOMIN bulletin on Chaitén and Llaima volcanoes
In the period between 4 and 20 August the eruptive activity of Chaitén has continued with the growth of the dome complex – particularly towards the western sector of the caldera – observable only occasionally because of the winter season. The column of gases, composed of water vapour and ash, has occasionally risen to 1.5 km above the complex.
Moreover, the quantity of pyroclastic material from fallen volcanic rock originating from both block-and-ash flows and lateral explosions has formed important accumulations in the adjacent valleys and especially towards the valley of the Chaitén river, from which the fresh occurrence of lahars towards Chaitén during torrential rains cannot be ruled out.
In consequence, given that the seismic activity remains elevated as a result of the growth of the dome complex, with the possibility of the generation of block-and-ash flows which may affect the surrounding valleys including the new generation of new lahars, SERNAGEOMIN maintains Volcanic Red Alert.
While seismicity at Llaima volcano tended to decrease in the early days of August, it has subsequently increased, slightly exceeding its usual values in this latest period (17-21 August). These oscillations in seismic activity (LP-type earthquakes [Long Period earthquakes] of high and low frequency) could be related to the rising and falling of the magma column located in the principal conduit of the volcano, demonstrating the instability of the magma column.
The absence of other types of seismic activity in this type of phenomenon suggests the existence of an unobstructed volcanic conduit, in which magmatic fluids can suddenly rise freely, bringing about a new eruptive phase.
Due to the markedly erratic behaviour which the volcano has shown during recent times, it is not possible to rule out its reactivation. Because of the foregoing, SERNAGEOMIN continues with Green Alert level 2, maintaining a 4-km radius of exclusion around the principal crater.
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
Erupción del Volcán Chaitén – extensive coverage of the Chaitén eruption
Global Volcanism Program: Llaima – summary information for Llaima (1507-11=)
Proyecto Observación Visual Volcán Llaima – Llaima Visual Observation Project
SERNAGEOMIN – Servicio Nacional de Geología y Minería, Chile