An explosive eruption from Mount St. Helens on 22 July 1980, seen here from the north, produced a Plinian eruption column that rose 16 km above the volcano. At the base of the column ash can be seen rising above a pyroclastic flow traveling down the N flank towards Spirit Lake. This was the third of three explosive pulses on July 22 and lasted more than two hours.

Photo by Jim Vallance, 1980 (U.S. Geological Survey).

Keywords: ash plume | eruption | explosive eruption | pyroclastic flow | Plinian | pyroclastic density current | PDC

St. Helens