This lateral blast of hot material accelerated to at least 300 miles per hour, then slowed as the rocks and ash fell to the ground and spread away from the volcano; several people escaping the blast on its western edge were able to keep ahead of the advancing cloud by driving 65 to 100 miles an hour!The blast cloud traveled as far as 17 miles northward from the volcano and the landslide traveled about 14 miles west, down the North Fork Toutle River.
1980-1986: Large explosive eruption on May 18, 1980, followed by 21 smaller eruptive episodes.
The last 17 episodes built a lava dome in the volcano's crater. 1800-1857: Large explosive eruption in 1800 was followed by extrusions of lava that formed a lava flow on the volcano's northwest flank (Floating Island lava flow) and a lava dome on the north flank (Goat Rocks lava dome). Helens on May 18, 1980 was an important geological event because we observed and documented large-scale catastrophic processes, which are extremely rare occurrences.
The largest and most destructive lahar was formed by water seeping from inside the huge landslide deposit through most of the day.
This sustained flow of water eroded material from both the landslide deposit and channel of the North Fork Toutle River.
Based on the best-selling book of the same name, this enthralling documentary features interviews with archaeological specialists and biblical scholars from all over the world, including experts from the Louvre, the Museum of Cairo, the Museum of Jerusalem, and the British Museum.