Chile Deals With Calbuco Volcano's Ash;More Eruptions,Lahars Feared

Four hundred Chilean troops have arrived in the scenic Los Lagos region to assist civilians in recovering from last week's eruption of the Calbuco volcano,the first major eruption in fifty years.There had been no discernible activity since 1972.Ash plumes are still billowing out of the volcano,and the National Office of Emergencies said there have been sporadic secondary explosions,correlated with seismic signals that are in turn associated with the movement of fluids inside the volcano,which suggests more eruptions are on the way.It is a very unstable situation for the trekking mecca.
More than 5,000 people were evacuated from the 20-kilometer exclusion zone,but some areas have been temporarily reopened so people can retrieve personal belongings and begin the cleanup process.The weight of ash has caused the collapse of homes,schools and bridges.It has an estimated aggregate weight of 250 million tonnes so far and has accumulated more than 50 centimeters,or about 19.25 inches,on roofs and streets.It looks like a gray desert,observers say.Lava has melted snow on the mountain,and ash is choking streams as well.There was an effort to rescue salmon from the rivers.Crops and trees are being laid waste.The event is similar in some ways to the eruption of Mount St.Helen's in Washington State on 18 May 1980-almost 35 years ago.
Just as with Mount St.Helen's,the threat of lahars looms large in the mind of scientists.A lahar is a swift,destructive flow of pyroclastic material in the form of hot gas and rock that comes out at a temperature of about 1000 degrees C/1380 F,moving at up to 700 kilometers/450 miles an hour,as well as water,mud and rocky debris,down or across the sides of a volcano.The flood may run hot or cold.It may include huge boulders and scour valleys out,stripping them of all vegetation and killing their wildlife.Millions of trees could be uprooted and deposited downstream by a lahar.Lakes can be devastated,and the channels of rivers and streams rerouted.Homes,bridges and other structures can be washed away or buried in the cataclysmic flow.Death may also befall humans who would not or could not evacuate.Some of Mount St.Helen's 57 victims have never been accounted for,and the unforgettable Spirit Lake was temporarily poisoned and clogged with a mat of tree trunks,the lakeside camps obliterated.Even a small volcanic explosion can trigger a lahar after the main eruption.
Just as with the Mount St.Helen's region,however,the residents of Los Lagos can be confident that,even as nature destroys the ecosystem,she can also heal it.While the people who perished in the eruption and lahars can never be replaced,the forests and wildlife around Mount St. Helen's,and even Spirit Lake,which started to recover within three years,have shown an incredible resilience.
An estimated 1.1 billion dollars of losses have been attributed to the Mount St.Helen's events.