Hawaii’s Kilauea volcano has been a hotbed of explosive activity since early May, gushing lava and toxic gases that have destroyed more than 25 homes and forced thousands of area residents to flee. Most recently, Kilauea's lava has begun flowing into the Pacific Ocean, generating plumes of toxic gas and steam called "laze" and shards of volcanic glass as the molten rock hits the seawater.

Kilauea has been continuously erupting since 1983 and is expected to remain a threat in the coming days and weeks. But what has its latest violent episode taught us about volcanic eruptions? How are scientists able to tell when a dormant volcano will rumble to life? And how does predicting volcanic eruptions compare to earthquake prediction and weather forecasting?

To learn the answers to these and other questions, NBC News MACH's Denise Chow spoke with Paul Segall, a professor of geophysics at Stanford University and a noted expert on volcanism. This interview has been edited for clarity and brevity.

MACH: How difficult is it to predict when a volcano is ramping up activity, or when we might see big eruptions like we’ve seen at Kilauea over the past two weeks?

Segall: Most eruptions — but not all — are preceded by precursory activity. We usually see an increase in the number and frequency of earthquakes. We usually see some evidence of ground deformation. Sometimes we see evidence of gas emission — volcanic gases coming out of the ground. It would be great if it was 100 percent of the time, and it would be great if we had more ability to turn that into specific forecasts as to when something might erupt. But we also have times when activity will build up and nothing will happen. There are false alarms.

How many of the world’s volcanoes are monitored for activity?

Very few volcanoes are monitored as extensively as Kilauea. It's one of the most heavily instrumented. It's kind of a test case for the best scenario. It's also a volcano that erupts very frequently, so it's worth putting a lot of resources there. There are many volcanoes that have not a single seismometer on them, so we wouldn't know except from regional earthquake networks, and the earthquakes would have to get pretty big before they'd be picked up by regional networks.