Medicine Lake Volcano

Medicine Lake Volcano is a large shield volcano in northeastern California about 30 mi northeast of Mount Shasta. The volcano is located in a zone of east-west crustal extension east of the main axis of the Cascade Volcanic Arc and the Cascade Range. The 0.6 mi thick shield is 22 mi from east to west and 28 to 31 mi from north to south, and covers more than 770 sq mi. The underlying rock has downwarped by 0.3 mi under the center of the volcano. The volcano is primarily composed of basalt and basaltic andesite lava flows, and has a 4.3 by 7.5 mi caldera at the center.

The Medicine Lake shield rises about 3,900 ft above the Modoc Plateau to an elevation of 7,795 ft. Lavas from Medicine Lake Volcano are estimated to be at least 140 cu mi in volume, making Medicine Lake the largest volcano by volume in the Cascade Range. Lava Beds National Monument lies on the northeast flank of the volcano.