Question

The violent flank eruption of Mount St. Helens in 1980 was set off by _______________ (A) an earthquake that caused the collapse of part of the mountain thus rapidly releasing pressure (B) They can form with little or no warning and move at extremely high velocities. (C) They can cover large areas with a dense cloud of ash and dust that can asphyxiate an entire city. (D) The temperature of the cloud can be several hundred degrees Centigrade causing fires.

Answer 1

(A) an earthquake that caused the collapse of part of the mountain thus rapidly releasing pressure