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Mount Lassen is only one of two volcanoes belonging to the Cascade Range that have erupted in the 20th Century – the other is Mount Saint Helens. Lassen Peak (the other name of Mount Lassen) is one of the biggest lava domes in the world and was part of what was once known as Mount Tehama.
The summit of Lassen Peak is located some 610 m above the terrain that surrounds it. This mountain holds the highest volume of snowfall in California. Although its average annual snowfall is about 16.8 m, it has a tendency to receive 25.4 m of snow in certain years.
Cascade Range, which stretches from British Columbia to Northern California, is part of the violent Pacific Ring of Fire. Aside from the two mentioned earlier, some of the volcanoes that form part of the Cascade Range are: Mount Rainier, Mount Jefferson, Mount Washington, Glacier Peak, Mount Baker, Mount Adams, Mount Hood, and Newberry Volcano. There are about 18 large volcanoes in the range.
The Cascade Range is a result of plate tectonics that has the North American plate overriding both the Juan De Fuca and Gordon plates. Just like other plate boundaries, the active tectonic activities in this region fuels volcanic eruptions. The formation of these peaks are estimated to have happened some 35 million years ago.
However, it was only some 27,000 years ago that Mount Lassen started rising to form its dome. Then between 25,000 to 18,000 years ago, glacial erosion took a bigger role in the formation of the mountain. The bowl-shape on Mount Lassen’s side, for instance is a result of glacial erosion.
This volcano’s most recent long-term activity stretched from 1914 to 1915, reaching a climax in that last year wherein the eruption released a 10 km tall mushroom-shaped cloud. That eruption is only second to the one of Mount Saint Helen’s in 1980 as the largest recent eruption in the US.
So large was the cloud of volcanic ash, that it was said to be visible even as far as Eureka, California.
Today, volcanic activity in Mount Lassen is being jointly monitored by the United States Geological Survey and the United States Park Service.
Mount Lassen is named after Peter Lassen, a Danish blacksmith who in the 1830s helped and guided immigrants past the mountain on their way to Sacramento Valley.
You can read more about convergent boundaries, one of the places where most mountains form, here in Universe Today. Here are the links:
There’s more about it at USGS. Here are a couple of sources there:
Here are two episodes at Astronomy Cast that you might want to check out as well: