Read the following passage, and answer the questions that follow

On April 30, 2018 the Pu’u ‘O’o crater on Hawaii’s Kilauea volcano, suddenly collapsed. It was the starting point for the volcano’s months long eruption, which went on to produce 320,000 Olympic-sized swimming pools’ worth of lava that transformed the landscape and ultimately destroyed 700 homes.

A volcanic eruption occurs when hot materials from the Earth's interior are thrown out of a volcano. Some eruptions are terrible explosions that throw out huge amounts of rock and volcanic ash and can kill many people. Some are quiet outflows of hot lava. Several more complex types of volcanic eruptions have been described by volcanologists. These are often named after famous volcanoes where that type of eruption has been seen. Some volcanoes may show only one type of eruption during a period of activity, while others may show a range of types in a series.

When does a volcanic eruption occur?

____________________________________________________________