Medicine Lake VulkanMedicine Lake is a large shield volcano in northeastern California about 50 km (30 mi) northeast of Mount Shasta, rising about 1,200 metres (3,900 ft) above the Modoc Plateau to an elevation of 2,376 metres (7,795 ft). It contains a 12 km x 7 km wide caldera.
The shield volcano is composed primarily of basaltic lava flows up to about 1 km thick, but measures 35 from E to W and 45 km from N to S, covering more than 2000 km2. Its sheer weight has bended the underlying strata down by 0.5 km under its center. It contains at least 600 km3 of lava, making it the most voluminous volcano of the Cascades.
Although it probably has not erupted for 1000 years, there have been at least 6 eruptions during the past 4,000 years, and it is likely to erupt again in the future. Its proximity to inhabited towns, roads and other infrastructure, it has been designated a "high threat volcano" by the USGS.
It is believed that the Medicine Lake volcano is fed by many small magma chambers rather than one large one.