The blocky surface of Chaos Jumbles in the foreground was produced by collapse of a portion of the Chaos Crags lava dome complex in the background about 1650 CE. The cold rock avalanche traveled 5 km from its source, and may have occurred in the absence of any eruptive activity. Three successive lobes of the avalanche cover an area of 8 km².

Photo by Lee Siebert, 1982 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Lassen Volcanic Center