Usually, when volcanic eruptions are mentioned, the first image that comes to mind is a classic vertical eruption in which volcanic ash, rock, and lava are being ejected from the volcano’s vent located at its peak. However, there are sometimes lateral eruptions, where a blast occurs on one of the volcano’s flanks. These are not as common as vertical eruptions, but some lateral eruptions that occurred throughout the 20th century have been studied extensively. Bezymianny in 1956, Arenal in 1968, Mount St. Helens in 1980, and Soufriere Hills in 1997 are some of the most well-known case studies. While they all experienced lateral eruptions, they were not under the same conditions. Composition plays a critical role in that the volcano can undergo degassing and lateral dike injection is important for magma to build up and exert pressure on any one of the volcano’s flanks. The internal volume of the magma also plays an important role because the amount of magma will help determine how much pressure can be exerted on the volcano’s edifice. Furthermore, depressurization can trigger a lateral blast, but it is not required to do so as several case studies have shown. However, the size of the eruption itself is irrelevant as long as some of the conditions are met leading up to the eruption.


Pollock, Megan


Earth Sciences; Geology


Geochemistry | Geology | Geomorphology | Volcanology

Publication Date


Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis



© Copyright 2021 Grant D. Holter