Ejecta
In volcanology , in particular , the term refers to particles including pyroclastic materials ( tephra ) that came out of a volcanic explosion and magma eruption volcanic vent , or crater , has traveled through the air or under water , and fell back on the ground surface or on the ocean floor . 
<triplet> volcanic <subj> volcanology <obj> studied by <subj> tephra <obj> made from material <triplet> crater <subj> volcanic <obj> part of