When Percy Jackson and Annabeth Chase investigated Mount Saint Helens for Hephaestus, they locate a group of Telekhines forging the blade of Kronos' scythe. Percy called upon his power and caused the mountain to erupt. This weakened the seal on Typhon's prison and lead to a reaction within the mountain that awakened him. It was reported that numerous illnesses and minor injuries were caused by the eruption. In addition, half a million people in the area were evacuated.
The mountain kept erupting and was soon obliterated, torn apart and completely destroyed when Typhon escaped from under the mountain.
- In real life, Mount Saint Helens was almost completely destroyed during an eruption in 1980.
- During the 1980 eruption, the mountain lost 1,300 feet off of its peak.