Tuesday, June 09, 2015
It seems like yesterday.
Mt St. Helens under a layer of snow, towering above Spirit Lake, just the place for a holiday of camping and hiking. 35 years ago, just before it blew its top leaving a horseshoe-shaped crater and devastation for miles. The top of the volcano was blocked by a plug of hardened magma so the mountain simply blew out of the side after an earthquake of 5.1. It caused one of the largest known debris avalanches in recorded history. The magma caused a massive pyroclastic flow of hot gas and wind down the side of the mountain flattening everything in its path over an area of 600 square kilometres. The debris was then carried further by the melted snow combined with earth as huge lahars flowed.
Thirty-five years later and the scars have still not quite healed. The horseshoe crater is still visible as is the new magma dome inside the crater. Beautiful Spirit Lake is in the upper centre of the image. At centre right of the image is Castle Lake. At right of Spirit Lake, debris avalanche deposits surround the tiny St. Helens Lake and the long line of Coldwater Lake.
Scientists estimate the eruption released over 1.5 million tonnes of sulfur dioxide into the atmosphere and recorded a Volcanic Explosivity Index of five.
This image was assembled from data acquired by the Operational Land Imager on Landsat 8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite.
Like I said, it just seems like yesterday. In geological terms, it's a blink which is why climate change deniers are going to be eating their words after another 35 years. And please, could we possibly have a Minister for Science some time before then and preferably not Greg Hunt who can't see the coral for the reef and insists that all that coal mining and coal shipping won't hurt the Great Barrier Reef at all, not a bit.