The size of volcanic eruptions is determined by the amount of lava emitted. The largest eruption over the past 2 centuries was Tambora in Indonesia in 1815.
Large volcanic eruptions are more frequent than asteroid impacts of similar magnitude.
Many volcanoes have been in continuous eruption for decades. Etna, Stromboli, and Yasur have been erupting for hundreds or thousands of years.
The following 4 volcanoes emit the most lava. Kilauea (Hawaii), Mt Etna (Italy), Piton de la Fournaise (Réunion), Nyamuragira, (D.R. Congo)
When there are no signs of an active magma chamber beneath the volcano (no unusual seismic activity, no volcanic gasses escaping etc.), and when there hasn't been any activity for a long time span (at least 10,000 years).
Some volcano eruptions throught history have been significant in their contribution to science. The following volcanoes were significant for their contribution to knowledge about eruptions, or occurred close to large populations.
Volcanism is a major factor on all of the terrestrial planets, so it has had a huge affect in forming the Earth, Mars, and Venus.
The fact that it is a continuous challenge. And this challenge involves both my body and my brain. My body because many places are hard to reach, my brain because I never end to learn and to have more curiosities.
I went to Western Washington University for my Bachilors degree, New Mexico Institute of Mining and Technology for my Master's degree and now I am here at University of North Dakota working on my Ph.D. I will be moving to the University of Oregon this Fall to complete my studies.
Here's one from Hawaii, and it involved flying in a helicopter, which is one of the more dangerous things that volcanologists do.
Misti is just over 19,000 feet high which is easily the highest volcano that I have ever studied. However, because it is an island and a large part of the volcano is below sea-level Erebus is the overall largest volcano that I have ever studied.
The scariest volcano experience that I had was also in Antarctica. The first time that I worked on the volcano I was there with a fairly large group of people, including a scientist who wanted to study gases that were coming out of the lava lake. To reach the lava lake, we first had climb down a steep face, using ropes, to reach the main crater floor. The lava lake was in an inner crater, another 3 or 4 hundred feet below that.