Volcanic Hazard key terms

What is magnitude?

Volcanic events range from small, slow lava flows to huge eruptions of lava, ash and gas.

Magnitude can be measured using the Volcanic Explosivity Index.

What is the Volcanic Explosivity Index?

Grades volcanoes from 0 to 8 based on the amount of material ejected and how high the material is blasted.

What is frequency?

Some active volcanoes erupt only once every 100,000 years or so, whereas others erupt every few months.

Generally, less frequent eruptions are larger in magnitude, and more damaging.

What is randomness vs regularity?

Some volcanoes erupt at very regular intervals, whereas others may be dormant for hundreds of thousands of years