Crater Lake is the remnant of a volcano formerly known as Mount Mazama. It is located 97 km NW of Klamath Falls, OR.
From a probable elevation of roughly 12,000 feet, the top of former Mount Mazama was lost to eruption and collapse that left the present caldera and the deepest lake (1,949 feet) in North America. The catastrophic, caldera-forming eruption that occurred 7,700 years ago is the largest known eruption from Cascade Range volcano. Since then, effusive eruptions built the Wizard Island volcano and two others on the caldera floor as Crater Lake filled to its present level. In the most recent known eruption, a small lava dome grew on the flank of the Wizard Island edifice about 4,800 years ago. Crater Lake is still hydrothermally active.
The Cascades Volcano Observatory and the PNSN cooperatively operate 4 seismometers on or near Crater Lake. On average, we locate 0 to 1 earthquakes within 10 km of the volcano each decade.