ejecta

The word "ejecta" refers to material that is forcefully thrown out during an eruption, impact, or similar violent event. It is most often used in geology, volcanology, and planetary science. When a volcano erupts, it does not only release molten rock. It can also send out ash, dust, lapilli, and large rock fragments. All of this thrown-out material can be described as ejecta. The amount, size, and spread of volcanic ejecta can tell geologists a great deal about how powerful the eruption was and what kind of magma was involved.

The term is also common in astronomy and planetary science. Impact craters on planets and moons are often surrounded by a blanket of ejecta, which is the dust and rock blasted outward from the point of impact. Studying this lunar or planetary ejecta helps scientists estimate the size and speed of the object that struck and learn more about the surface that was hit.

Outside those fields, the word is less common, and people would usually say "debris" or "material" instead. Still, the basic idea stays the same: something has been blasted, thrown, or pushed out from where it started. So, whether it is ash falling around a volcano or rock scattered around a fresh crater, ejecta is the material sent outward by the event.