The Mt. St. Helens Eruption 1980 The Mount Saint Helens Eruption.wmv - YouTube
2 long term impacts on Mt. St. Helens: The formation of the volcano is now completely changed. The stratovolcano's northside completely collapsed during the 1980 eruption leaving a gaping crater. The ecosystem was also majorely impacted...rivers and streams contained the contaminated sediments for more than a decade.
The eruption of Mt. St. Helens is similar to another stratovolcano in Mexico, El Chichon. Their pyroclastic flows were the first the first ones studies using modern techniques.