What were the destruction of mount st Helens?

Answer 1

In the 1980 eruption of Mount St. helens the near-supersonic lateral blast, loaded with volcanic debris, caused widespread devastation as far as 19 miles from the volcano. The area affected by the blast can be subdivided into three roughly concentric zones: Direct blast zone, the innermost zone, averaged about 8 miles in radius, an area in which virtually everything, natural or manmade, was obliterated or carried away. For this reason, this zone also has been called the tree-removal zone." The flow of the material carried by the blast was not deflected by topographic features in this zone. Channelized blast zone, an intermediate zone, extended out to distances as far as 19 miles from the volcano, an area in which the flow flattened everything in its path and was channeled to some extent by topography. In this zone, the force and direction of the blast are strikingly demonstrated by the parallel alignment of toppled large trees, broken off at the base of the trunk as if they were blades of grass mown by a scythe. This zone was also known as the "tree-down zone." Seared zone, also called the "standing dead" zone, the outermost fringe of the impacted area, a zone in which trees remained standing, but singed brown by the hot gases of the blast.