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Latest Earthquake | Chat Share
When a volcano erupts explosively, an ash cloud will be produced. Its size and travel-distance are determined by the amount of material erupted, the height of the cloud, plus the wind directions and speeds. Knowing where the ash cloud might travel is critical for managing air space and warning downwind communities to be ready for possible ash fall.
The following three Ash3D computer simulations, developed by the USGS, use current wind speed and directional data from the National Oceanic and Atmospheric Administration along with eruption size parameters set by volcanologists to model the potential path of an ash cloud if an eruption were to occur from Mount St. Helens today. This does not mean an eruption has occurred. Read the CVO activity update for information on current volcanic conditions.
For a relatively large eruption similar in size to Mount St. Helens, May 18, 1980:
For a relatively moderate eruption similar in size to Mount Spurr, Alaska, August 18, 1992:
For a relatively small eruption similar in size to Mount St. Helens, July 22, 1980:
What do these graphics show?
How can you be prepared for ash hazards?
Read about the hazards and impacts associated with ash fall. To be prepared for potential ash fall, read about our guidelines for a safety plan and survival kit. During an eruption, stay informed by listening to emergency broadcasts. You may be asked to stay sheltered in place until the ash fall is over.