What's it like during ashfall?

Notification of advancing eruption clouds are often possible.

Scientists monitor a volcano using several methods, especially during times of increased activity. They typically work with many organizations, businesses, emergency-management professionals, and the media in order to disseminate current information about the likelihood of eruptive activity and the status of an ongoing eruption, including the development of an eruption column.

If scientists know that a volcano is erupting but they or others cannot see it (for example, at night or during poor weather conditions), it is not always possible to determine right away whether an eruption column with the potential for generating ashfall downwind has actually formed. Often, pilots of private and commercial aircraft are the first to verify the existence of an eruption column and a corresponding eruption cloud. Sometimes, verification of an eruption cloud capable of generating ashfall comes from small communities or individuals located within a few tens of kilometers of the volcano.

Meteorological organizations typically issue weather and wind forecasts that can serve to help determine which areas could be affected by an ashfall from a specific volcano. News organizations may use this information to report on the areas likely to get ash if an explosive eruption at a specific volcano were to occur in the next 12 to 24 hours. For notification of eruption clouds:

  • learn how volcano and meteorological information is disseminated in your area or region; and
  • when a volcano in your area is active and ash-producing eruptions are possible, make preparations for yourself, family, and business for an ashfall (see "What can I do").

Small explosion clouds and minor ashfall

Large explosions clouds and heavy ashfall

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