Mount Vesuvius in Italy erupted in March, 1944, destroying a number of villages.
North American soldiers were in the area at the time, fighting in the Second World War.
The original caption of the picture reads:
Crew member cleaning the ashes and cinders off the wing of a North American B-25 of the 340th Bomb Group. This was caused by the eruption of Mt. Vesuvius on 23 March 1944.