tephra

noun (used with a plural verb)

1. clastic volcanic material, as scoria, dust, etc., ejected during an eruption.

noun

1. mainly US solid matter ejected during a volcanic eruption

1. Solid matter, such as ash, dust, and cinders, that is ejected into the air by an erupting volcano. Tephra is a general term for all pyroclastic materials ejected from a volcano.