<P> An earthquake at 8 : 32 : 17 a.m. PDT ( UTC − 7 ) on Sunday , May 18 , 1980 , caused the entire weakened north face to slide away , creating the largest landslide ever recorded . This allowed the partly molten , high - pressure gas - and steam - rich rock in the volcano to suddenly explode northwards toward Spirit Lake in a hot mix of lava and pulverized older rock , overtaking the avalanching face . </P>
<P> An earthquake at 8 : 32 : 17 a.m. PDT ( UTC − 7 ) on Sunday , May 18 , 1980 , caused the entire weakened north face to slide away , creating the largest landslide ever recorded . This allowed the partly molten , high - pressure gas - and steam - rich rock in the volcano to suddenly explode northwards toward Spirit Lake in a hot mix of lava and pulverized older rock , overtaking the avalanching face . </P>
when did mount st helens blew its top off
when did mount st helens blew its top off
8 : 32 : 17 a.m. PDT ( UTC − 7 ) on Sunday , May 18 , 1980
8 : 32 : 17 a.m. PDT ( UTC − 7 ) on Sunday , May 18 , 1980