Deep beneath the Pacific, another active Hawaiian volcano waits to emerge

 
Although no one directly witnessed the eruption — as that would mean waiting in a deep-sea submersible at a reasonable distance away — scientists still knew about it. Lo‘ihi sits on the side of the Big Island, so the strong earthquakes that typically accompany eruptions were picked up by Hawaii's seismic monitoring instruments. 

"It was one of the most energetic earthquake swarms that we had ever seen in Hawaii," Jackie Caplan-Auerbach, an associate professor of geology at Western Washington University, said in an interview. 

Caplan-Auerbach spent a couple years directly studying Lo‘ihi, floating above it in a research vessel and once even taking a submersible down to the volcano.