New USGS Study Details Which California Volcanoes Pose Highest Threat

When Lassen Peak exploded on May 22, 1915, it sent a pyroclastic flow flying down the northeast flank of the volcano, creating a zone now known as the Devastated Area. The flow knocked trees down and destroyed everything in its path — 3 square miles of wilderness was obliterated. In this file photo, ash and smoke spew from Mt. Lassen. (Credit: National Park Service)

When Lassen Peak exploded on May 22, 1915, it sent a pyroclastic flow flying down the northeast flank of the volcano, creating a zone now known as the Devastated Area. The flow knocked trees down and destroyed everything in its path — 3 square miles of wilderness was obliterated. In this file photo, ash and smoke spew from Mt. Lassen. (Credit: National Park Service)

Researchers say nearly 200,000 people live, work or pass through California’s volcanic hazard zones on a daily basis, and there’s a 16 percent probability of an eruption in the next 30 years.

A study released Monday by the U.S. Geological Survey attempts to characterize the exposure of population, infrastructure, resources and the economy from an eruption in any of eight areas statewide that are designated as having moderate, high or very high threat.

Scientist-in-charge Magaret Mangan of the California Volcano Observatory says the report is not a doomsday scenario.

Rather, she says, it should be a springboard for launching studies of the vulnerabilities of specific sites.

The areas include Northern California’s Lassen Volcanic Center, where the state’s last eruption occurred between 1914 and 1917.

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