|Public domain image. SOURCE.|
The field examines the formation and classification of volcanoes, matter expelled during eruptions (pyroclastic flows, lava, dust, ash, gases), volcanic relations to other geologic events (mountain building, earthquakes), and attempts to predict when volcanoes may erupt. It also involves geophysics, geochemistry, seismology, and geodesy.
Volcanoes form because of rising magma from beneath the surface of Earth, usually close to the edges of tectonic plates. There are three types of volcanic activity: spreading center volcanism (takes place along diverging plates), subduction zone volcanism (takes place where two plates converge) and intraplate volcanism (takes place mid-plate where there are no plate edges).
Volcano types are further classified as cones (steeply sloped with the typical volcano shape), shield volcanoes (shallow sloped), and stratovolcanoes (also known as composite volcanoes; they are shallow at the base, curves sharply upward toward the top). Some major kinds of eruptions include fissure eruptions (eruptions occur along a line), Hawaiian eruptions (relatively calm flows of basalt lava with little volcanic gas), Strombolian eruptions (explosive, noisy eruptions that involve a lot of volcanic gas), Vulcanian eruptions (short series of eruptions that send up a lot of rocks at the onset but become quieter and steadier after some time), Plinian eruptions (generate plumes of ash that travel up to 45 km into the air), and hydrovolcanic eruptions (eruptions that happen in water).
|By Ahjartar, CC-BY-SA-3.0. SOURCE.|
Haraldur Sigurðsson is a volcanologist and marine geologist. He received a Ph.D. in Petrology/Geochemistry from Durham University and is a current Professor of Oceanography at the University of Rhode Island. He has studied volcanoes in Iceland, North America, South America, the Caribbean, Indonesia, Italy, and Africa, and has researched underwater volcanoes. He was awarded the Coke Medal by the Geological Society of London for his work. Sigurðsson has also hosted several TV documentaries, including The Riddle of Pompeii, Horizon, Naked Science, and Timewatch.
Video with Haraldur Sigurðsson (embedding was disabled, so I couldn't put it directly in this post):
Do you live near any volcanoes?
-----The Golden Eagle