100th year anniversary of the last Mt Lassen eruption

Why Have Volcanoes in the Cascades Been So Quiet Lately?
Erik Klemetti Date of Publication: 05.22.15.

This week marks the 100th anniversary of the eruption of California’s Lassen Peak. As the anniversary slides past, it leaves Mount St. Helens as the only Cascade Range volcano that has erupted over the last century. This means that although we have thirteen major composite volcanoes plus a multitude of smaller cinder cones and lava domes running from California into Canada, only one has experienced an eruption in the past 100 years. Does that mean we don’t have to worry about the Cascades as a volcanic hazard anymore? That answer is decidedly “no” … but why?

http://www.wired.com/2015/05/volcanoes-cascades-quiet-lately/
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Four Days in May: Mount Lassen Erupted 100 Years Ago
Andrew Alden, KQED Science Contributor | May 22, 2015 | 0 Comments

One afternoon in the spring of 1914, Mount Lassen awoke with a cough, the sudden burst of steam and ash from its 10,500-foot summit startling residents of the northernmost Central Valley and surrounding mountains.

Burt McKenzie, a cattleman in the high meadows nearby, telephoned a Forest Service ranger and told him the mountain was “blowing up.” The ranger checked it out on snowshoes the next day. Soon he and other climbers confirmed that the explosion had left a smoking crater about 100 by 350 feet in size, ringed with fresh volcanic ash and puffing sulfurous fumes.

Similar activity continued for a year: small explosions and mostly harmless clouds of steam and ash. Newspapers entertained the country’s readers with the newest sensation from colorful California. Local photographers staked out the good spots and sold their images to all and sundry.

Since that time, geologists have learned to discount those historic newspaper stories and prize those historic photographs instead. Michael Clynne, who has studied Lassen for the U.S. Geological Survey since 1975, told an audience last month that about 1,000 different photographs survive showing Lassen in action. With their help and lots of scientific sleuthing, we have made sense of California’s first and only volcanic eruption since statehood.

Mount Lassen was awake for just over three years, from that first blowout in May 1914 until a final burp in June 1917. It climaxed in a proper eruption, with red-hot lava and everything, over the four days of May 19-22, 1915 — 100 years ago this week.

http://blogs.kqed.org/science/2015/05/22/four-days-in-may-mount-lassen-erupted-100-years-ago/