Geology and History

Eruption History for Mount Mazama and Crater Lake Caldera

The climactic eruption of Mount Mazama devastated the terrain for tens of kilometers from the volcano, sent pyroclastic flows as far as 70 km (43 mi) down every valley heading on the volcano, and produced ash fall throughout much of the Pacific Northwest and parts of southern Canada.

Since the climactic eruption of Mount Mazama, “postcaldera volcanism,” has been confined within the caldera.

In the summer of 2000 scientists surveyed the lake floor with modern techniques to provide a bathymetric (depth) map for interpreting the postcaldera geologic history.

The long history of volcanism at Mount Mazama, the volcano that houses Crater Lake, suggests that this volcanic center will be active in the future. Future eruptions will likely occur within the caldera and probably beneath the water's surface.

Mount Mazama is one of the major volcanoes of the Cascades Arc.

Crater Lake National Park was dedicated in 1902 and encompasses 645 square kilometers of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama.