Explosive eruptions can blast pebble- to boulder-sized fragments of rock, ice, or pumice into the air, where they travel on arcuate, ballistic trajectories away from the vent. These projectiles, called ballistics, fall at high speed, and can injure or kill people, and crush or damage equipment and buildings. Most ballistics will fall within a few kilometers of the vent.
DGGS online catalog of government agency publications relating to: Ballistics
Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS) 3354 College Road, Fairbanks, AK 99709