Pyroclastic flow from Mayon Volcano, Philippines. A PC flow is a ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas that rushes down the side of a volcano as fast as 100 km/hour or more. The temperature within a pyroclastic flow may exceed 500° C.   USGS Photo by Chris Newhall, September, 1984.

           Return to Archive or go to Next Photo.