Eruption-triggered avalanche, flood, and lahar at mount st. Helens--effects of winter snowpack.
An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.
Waitt
R B
RB
Pierson
T C
TC
Macleod
N S
NS
Janda
R J
RJ
Voight
B
B
Holcomb
R T
RT