Sentence:  The Los Alamos mesa rested against the eastern slope of the Jemez Mountains, on the rime of the Valles Caldera, formed as a result of two explosive <WSD>super-eruptions</WSD> 1.6 and 1.1 million years ago. 
Meaning of the word marked with <WSD> tags:  The massive eruption of a supervolcano. (from 20th c.)