Saturday, May 24, 2008

Chaitén: news from SERNAGEOMIN, 22 May 2008

SERNAGEOMIN have issued a new bulletin today about the situation at Chaitén. The key point is that Chaitén volcano is now busy building a lava dome: ‘The eruptive activity is continuing and has begun a phase of dome construction (the slow accumulation of viscose lava around an eruptive centre) inside the active crater, on the north flank of the old dome’. From its northern flank the new dome is active with ’sporadic explosions’ and the generation of ’profuse pyroclastic flows’, while from its western side ‘a white eruption column of steam’ is being produced. To the south of the new dome is the vent from which the main eruptive activity of the last few weeks has emerged; there ’the main eruption column remains vigorous but low, pushed to the south-east by the prevailing winds. In general the column has maintained an oscillatory form, with occasional explosions lifting it above the volcanic edifice’.

The SERNAGEOMIN report includes this photograph, which is a view within Chaitén crater, looking southwards:

view of the new lava dome. SERNAGEOMIN image.

The new dome (’Domo nuevo’) is in the foreground, with its slopes of debris and reddish eruption plume. it rises from the northern flank of the old dome (’Domo antiguo’). Behind the new dome is a white steam plume (’Columna principal’) erupting from the active vent on the southern side of the old dome. A larger version of this image, without the captions, can be found here.

The bulletin reports that the new seismic networks installed by SERNAGEOMIN and the USGS are being activitated today. The new network will be invaluable in assessing the processes now under way at the volcano and clarifying potential SERNAGEOMIN is maintaining volcanic red alert and continues to be concerned about possible major explosions producing the destruction of the old dome and the generation of pyroclastic flows. Nor can the occurrence of lateral explosions be disregarded. The eruptive dynamic now includes the evolution of the new dome, the growth and collapse of which can, in turn, generate pyrocastic flows on its flanks.