What can cause a volcano to erupt out of the sudden?

While sudden eruptions of volcanos is rare, and usually means that we missed the telltale signs of an impending eruption, some volcanos in history have “surprised us”, most notably the eruption of Vesuvius in 79 AD. read more

A third example, from 2014, was Mt Ontake, was the sudden eruption on a busy Saturday, catching many hikers on the volcano slopes, and causing many deaths. One scientist noted that typically you would get 24 to 72 hours of warning - magmatic quakes, ash clouds, micro-seismic movement. read more

The “Big Island” as Hawaii is known, has 5 active volcanoes- Maura Loa, Mauna Kea , Kohala, Hualalai and Kilauea. Out of those 5 only Kilauea is erupting. read more