Final answer:
Mount St. Helens' 1980 eruption was catastrophic and explosive, reducing the mountain's height and decimating surrounding ecosystems, while Kilauea's eruptions are typically less explosive and preserve the local environment.
Step-by-step explanation:
The eruption of Mount St. Helens in 1980 was a cataclysmic event that contrasts with the typical eruptions seen at Hawaii's Kilauea volcano. Mount St. Helens' explosion caused a massive debris avalanche, significantly reducing the peak's height from 9,677 ft to 8,363 ft and leaving a 1-mile-wide horseshoe-shaped crater.
The eruption released a large amount of carbon-containing gases and devastated the forests on the north side, creating new soil devoid of any pre-existing ecosystem. In contrast, Kilauea is known for its effusive eruptions that create lava flows and are less explosive.
Kilauea's eruptions are associated with mantle hot spots rather than the subduction zones that characterize the Cascades and tend to be less destructive, preserving surrounding ecosystems.