Deposits of pre-1980 pyroclastic flows and lahars from Mount St. Helens Volcano, Washington

The early part of the Kalama eruptive period may be analogous to the dacitic eruptive activity that began at Mount St. Helens in 1980 with an explosive eruption followed by dome extrusion. If the current eruptive sequence repeats the events of Kalama time, future volcanic activity will include multiple eruptions of dacite in the form of domes, tephra, and pyroclastic flows, and andesite in the form of lava flows, tephra, and pyroclastic flows, and will continue intermittently for at least a century.