ejecta

In volcanic regions tephra (erupted ash) may also contribute to soil depth and fertility.

…by an explosive blast, and solid fragments are ejected in a great cloud of ash-laden gas that rises tens of thousands of metres into the air. One feared phenomenon accompanying some explosive eruptions is the nuée ardente, or pyroclastic flow, a fluidized mixture of hot gas and incandescent particles that…

…creating what are known as pyroclastic fragments. (The term pyroclastic derives from the Greek pyro, meaning “fire,” and clastic, meaning “broken.”) Pyroclastic materials are classified according to their size, measured in millimetres: dust (less than 0.6 mm [0.02 inch]), ash (fragments between 0.6 and 2 mm [0.02 to 0.08 inch]),…