You might think that while California has earthquakes all the volcanic activity is up north in Washington State. You would be wrong, Lassen Peak in California had its last major eruption in 1914/15 and from then it was considered to be the only active volcano in the ‘Lower 48’ states of the USA. It was not until 1980 that Mount St Helens stole Lassen’s unique selling point by coming to life in a spectacular fashion. The area around Lassen Peak became a National Park in 1916 to preserve its scenery from the threat of logging and uncontrolled tourist development. The geothermal features here don’t come close to matching Yellowstone, but if Wyoming is too far to go then Lassen will provide an excellent introduction to volcanic activity.

Lake Helen

Away from the area affected by recent volcanic activity can be found some stunning lake scenery. Lake Helen is typical of these; a mountain lake whose deep blue colour is attributed to minerals in the water. At an elevation of around 2,800 metres (9200 feet) the air is very clear giving the picture and almost unreal clarity and colour saturation. In winter this area is covered in deep snow, but even in summer the 33 metre (110 foot) deep lake remains extremely cold.

Lassen Volcanic National Park

Sulphur Works

For those who lack the time or energy to walk to Bumpass Hell, there is some geothermal activity  right by the road through the National Park near the southwest entrance. You won’t see boiling mud pots or brightly coloured pools here, but these steam vents do emit a smell of pure volcano. If you are sensitive to the smell of sulphur, don’t get too close!

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Boiling Pool, Bumpass Hell

You won’t find geysers spouting at Bumpass Hell, but the sulphurous crust and boiling pools create a riot of colour and the steam makes it seem rather surreal. The unstable nature of the ground here was brought home to us when we revisited  in 2006 after a gap of 25 years. Although the setting of Bumpass Hell was unchanged the walkways and the layout of the pools had undergone significant change.

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Bumpass Hell

The Peak may have been quiet since 1921 but there there are still plenty of other signs of activity. A 2.4 kilometre (1.5 mile)  walk from the road through the park takes you to Bumpass Hell, a geothermal basin containing fumaroles, mudpots and hot springs. It is named explorer Kendall Vanhook Bumpass who in 1864 lost a leg after falling through the crust into a boiling pool. The area remains very dangerous so wooden walkways have been erected for safe viewing of the area. Click on Tab 2 for a view of a boiling mud pot.

Lassen Peak & the devastated area

Although over 50 years had elapsed when this picture was taken in 1981, the damage caused by the 1914/15 eruption was still clearly visible. Lassen did not blow off its top Mount St Helens style, instead the damage was caused in May 1915 by a Pyroclastic Flow of hot mud and gas that raced down the mountain from the main vent flattening everything in its path for 6 kilometres (4 miles). The cloud created by the eruption is estimated to have reached 12 kilometres (40,000 feet) high. Although the Lassen quietened down after 1915, minor eruptions continued until 1921 but since then the peak has been dormant. When we revisited Lassen Volcanic National Park in 2006 we found that the trees in the foreground had grown, masking much of this view.

© Mike  Elsden 1981 - 2025

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