Rex Trulove
This is the image of Crater Lake that many people may have seen.
Crater Lake formed about 8,000 years ago after a large mountain named Mount Mazama underwent the last of a series of large number of explosive volcanic eruptions. Unlike the eruption of the much smaller Mount Saint Helens, and despite what a person might think, the caldera that the lake partly fills wasn’t the result of Mount Mazama ‘blowing its top’.
Rather, the magma chamber under the lake became depleted during the last major eruption. This created an immense void or hollow empty spot inside the mountain. The billions of tons of rock were no longer supported so the mountain top collapsed into the void.
Over the course of thousands of years, snow runoff filled the lake. Although the lake is only about six miles across, it contains an enormous amount of water. Part of this is due to the fact that this is the deepest lake in the United States. Give or take, Crater Lake is about 4,942 feet deep, though the bottom has still not been fully mapped.
There are no streams that flow into or out of the lake. The water level is maintained through precipitation, primarily in the form of snow.
Wizard Island, in the center of this image, was created by a small eruption after the mountain collapsed and it is a cinder cone.
