When something spews out a substance or when a substance spews from something, the substance flows out quickly in large quantities.
The volcano spewed out more scorching volcanic ashes, gases and rocks. [VERB noun with adverb]
Leaking oil spewed from the tanker. [VERB preposition]
An oil tanker spewed its cargo into the sea. [VERB noun preposition]
Synonyms: shed, discharge, send out, issue