Lassen National Park – 100 Years of Changing Landscape

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The Cascade Mountains stretch from southern British Columbia, Canada, all the way into northern California. Part of the famed Ring of Fire – a string of volcanoes and mountains running throughout the Pacific Ocean – the southern Cascades contain hundreds of small- to medium-sized volcanoes. This includes more than 30 volcanoes that make up California’s Lassen Volcanic National Park.

This week marks the 100th anniversary of one of Lassen’s most powerful volcanic eruptions.

Mt. Lassen before the eruption.

Formed approximately 30,000 years ago, Lassen Peak began as a volcanic vent on Mount Tehama (also known as Brokeoff Mountain). Eroded by glaciers during the last Ice Age, Lassen’s May 19, 1915, eruption changed the area’s landscape and stirred the American imagination.

Eruptions actually began in May 1914. The first explosion generated a small crater at the summit of Lassen Peak. Over the next 11 months, steam explosions blasted out a crater 1,000 feet (300 m) long. The ultimate explosion on May 22 was the worst since Europeans settled the West in the late 1800s.

Visible from as far away as Eureka on California’s coast, the vertical eruption column rose to a spectacular 30,000 feet. Its partial collapse generated a high-speed avalanche of hot ash, pumice, rock fragments and gas that swept down the northeast side of the volcano, rushing down to Old Station, flooding lower Hat Creek Valley.

Lassen erupting, photo by B.F. Loomis, courtesy of National Park Service.

The half-mile wide lava and mudflow partially dammed lakes and creeks, completely obliterated Jessen Meadows and destroyed an estimated 5 million board feet of trees in what’s now called the Devastated Area. Ash rained down as far away as Elko, Nevada – 280 miles away.

In the early 20th century the Lassen area was home to two national monuments – Lassen Peak and Cinder Cone, the park’s second-most famous volcano which a study by the USGS and the Park Service established was formed during eruptions in 1666.

But it was Lassen’s dramatic eruption and the stunning pictures captured by local businessman and amateur photographer Benjamin Franklin Loomis that helped create the current National Park in 1916, which now encompasses 106,372 acres.

Lassen Devastated after 1915 eruption. Photo by B.F. Loomis, courtesy of National Park Service.

Lassen – Butte Lake after the 1915 eruption.

Although Lassen Peak has been relatively benign since its 1915 eruption, it is still an active volcano, says Michael Clynne, PhD., lead researcher with the United States Geological Survey (USGS). Clynne has worked with the National Park Service at Lassen since 1975.

The USGS worked with the park service to study Lassen’s geothermal activity. After Mount St. Helens erupted in 1980, this work folded into the Volcano Hazards program where the USGS reevaluated risks posed by other potentially active volcanoes in the Cascade range.

One of the surprises they found, said Clynne, is that Lassen has a large integrated volcanic system. And its amazing hydrothermals are driven by steam generated by boiling of an underground reservoir of hot water. These include fumaroles (steam and volcanic-gas vents), bubbling mudpots (hot springs with boiling mud), boiling pools, and steaming ground. All are related to active volcanism and are indications of the ongoing potential for future eruptions from the Lassen volcanic center.

Infrared photo of Lassen Cinder Cone.

“The geothermal system (whose reservoir is about 240 degrees Celsius or 464 Fahrenheit.} tells us there’s magma in the subsurface,” said Clynne, “and it could potentially become eruptable.”.

But the USGS California Volcano Observatory in Menlo Park, California, operates a sophisticated sensor network to detect any increase in seismicity, ground deformation, or gas emissions that could indicate magma rising toward the surface ahead of any future Lassen eruption.

The seismic network includes nine seismometers based around the volcano. Its information is telemetered to the Observatory and interpreted. GPS locations around the volcano monitor ground formation. They’re sensitive enough to note if the magma starts to rise and the ground’s surface is disturbed.

“We’re monitoring it,” said Clynne. “(But) it’s a wonderful natural laboratory for studying volcanoes.”

Lassen is certainly going to erupt in the future, Clynne said. “It’s an active volcano. (But) volcanoes are like people,” he said. “Each one has its own individual characteristics and behavior. (That’s) why we have to understand their history, to study what they’ve done in the past. If we know what (they’ve done), we’ll know what to expect.”

For now, Lassen and its natural wonders are to be enjoyed and appreciated. And to remember that natural cataclysm that occurred a century ago.

Click here to learn more about the 100th anniversary and here to read Doni Chamberlain’s conversation with radio host and Lassen Volcanic National Park volunteer Dave Schlom.

To reach Debra Atlas, contact her at or via her blog at

A former long-term resident of Redding who loves its natural wonders, journalist and blogger Debra Atlas is reachable or
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7 Responses

  1. Avatar Sheila Barnes says:

    Very interesting article. What else is interesting is that yesterday, when I was at a volunteer recognition event, the fellow sitting next to me shared that he could predict earthquakes and that he had been invited on the Oprah show to talk about this along with other folks who were able to make predictions about “natural events”. I think he said this was in the 1990’s that he was on the show. He told me there would be an earthquake “soon”. He did not specify when, but mentioned the time table in weeks or months. He mentioned Mount Lassen and Mount Shasta. I did not initiate the topic of conversation with this fellow. I guess he felt a need to share. I am not judging the credence of what he told me, nor am I jumping on any believer bandwagon. I am posting this as an interesting – and perhaps timely – observation.

    • Avatar Dearth Johnson says:

      In light of the geothermal nature of this region, predicating a “significant” earthquake within weeks or months is no more meaingful or indicative of special abilities than an augering that a large ball of burning hydrogen will be present in the sky tomorrow.

  2. Randall R. Smith Randall R. Smith says:

    Interesting article. I was unaware that Cinder Cone and Lassen both ejected material in 1915. I had previously been told that the Cinder Cone was perhaps last active during travel of wagons using the Noble Trail which passes its north shoulder and is still easily seen.

    • Dave Schlom Dave Schlom says:

      Absolutely not true. Cinder Cone’s last eruption was in 1666. Not sure where you got that bit of misinformation. misinformation. Certainly not from us at the NPS and the USGS.

  3. Avatar Debra Atlas says:

    Dave and Randy:

    First thanks for reading my article and for your comments.
    As I mentioned in the article, I was told by Michael Clynne, the leading expert on Lassen, that a study conducted by the U.S. Geological Survey with the Natl. Park Service established that Cinder Cone was formed during eruptions during 1666 (the newest date was made via tree ring dating).

    Hope this clears up any confusion.


  4. Dave Schlom Dave Schlom says:

    Your article was excellent. Not sure where that reader got the 1915 coupling with Cinder Cone…

  5. Dave Schlom Dave Schlom says:

    Now I see where the confusion came from. The image of the tephra fall out is from Cinder Cone in 1666. Nothing to do with 1915…The caption is what is misleading.