In the event of a volcano eruption what does a volcanologist do?

They risk their lives in order to get information on the eruption. Part of their job is to place instruments around the Volcano, that read how hard the Earth shakes, if that area is rising, how hot it is there, gases produced, etc. By being near the Volcano when it is active, they are putting their lives at risk to further the knowledge of how to predict, when it will erupt, how big the eruption will be, what direction, and who is in harms way (towns, cities, etc.)