- Estimated Date: Between 5,900 to 5690 BCE)
- Location: Oregon, United States
- VEI Rating: 6
Mount Mazama is considered a complex volcano, which consists of volcanic centers and has a mixed landform. They tend to form due to changes in eruptive habits or in the location of the principal vent area of another volcano. Most of these mountains in the Cascade Volcanic Arc formed around 7,700 years ago. The collapse of the volcano formed a caldera that now holds “Crater Lake.” Mount Mazama was originally 12,000 feet but the climactic eruption and subsequent caldera took it down to 8,157 feet. Crater Lake itself is actually 1,943 feet deep. This is the deepest freshwater body source in the United States and the second deepest in North America.
Overlapping volcano edifices including shield volcanoes and composite cones became active at the same time, eventually resulting in a major eruption sometime between 5900 to 5680 BCE. The eruption destroyed Mazama’s summit but led to the major volcano and crater lake we see today. Interestingly, the volcanic activity here is taking place due to the subduction of the offshore oceanic plate, which influences local extensional faulting. While Mazama might be dormant, scientists claim smaller eruptions are still likely and could cause major problems to the surrounding cities.