Hazard Description

Why can't we predict when a volcano will erupt?

A volcano is an opening or rupture in the earth’s surface that allows ash, gases, and/or molten rock under tremendous pressure to emerge from below the surface. Depending on the type of volcano, an eruption can be among the more spectacular of natural hazard events, ejecting materials thousands of feet into the air, darkening skies, and blanketing surrounding areas with a fine powdery ash or rivers of molten lava. 


No active volcanoes are located within Washoe County; the three closest potentially active volcanoes to Washoe County are located in California. However, Washoe County is close enough to the Long Valley Caldera to be impacted by ash fall. Ash fall could significantly affect airplanes, air quality, and highway driving, as well as cause failure of combustion engines and damage to crops. Eruptions could cause local economic impacts, particularly in the agricultural and transportation and distribution sectors. 


Due to advanced geologic and seismic monitoring techniques, warning time for major eruptions is usually measured in weeks or months so disaster mitigation can occur.

Sign-up for Alerts

Citizens can register for reverse telephone notification, called Code Red, as well as other notifications concerning alerts. To sign up, click on the “Regional Notification” link on the menu and follow the instructions.

To learn more about the California Volcano Observatory, click here.