The Mt. Spurr eruption, July 9, 1953

Abstract

The July 9, 1953 eruption of a subsidiary cone of Mt. Spurr, Alaska, is of particular interest because the initial phases were under close observation by the crews of two jet aircraft which were in the vicinity when the eruption started. Within one hour the eruption cloud assumed a mushroom shape which reached an altitude of approximately 70,000 ft. Extremely heavy rains accompanying the eruption, and water supplied by the melting of ice in the immediate vicinity of the vent, caused flash floods which carried sufficient debris to dam one of the major rivers in the area and form a lake nearly five miles long. A one‐quarter‐inch blanket of ash was deposited on the city of Anchorage, 80 mi from Mt. Spurr; but, in the opposite direction, no discoloration of snow fields and glaciers could be seen within two or three miles of the volcano. Observations of this eruption of Mt. Spurr particularly emphasize the importance of prevailing wind direction in the control of ash‐fall distribution resulting from an eruption of this type.