Subaerial Fallout Tephra

The transport modes of subaerial fallout tephra are (1) by ballistic trajectory and (2) by turbulent suspension. Energy is supplied initially to fragments by the eruption and later by wind. Tephra that falls from the atmosphere onto land is called subaerial fallout or airfall tephra. Tephra deposited in standing water is called subaqueous fallout tephra and includes (1) submarine or marine tephra, and (2) sub- lacustrine tephra. Subaqueous fallout tephra originating from eruptions on land is discussed separately (Chap. 7) from pyroclastic materials originating wholly beneath water (Chap. 10). Island arc and oceanic island flank environments generally include both kinds.