Santa Maria Volcano , Guatemala. The eruption of Santa Maria volcano in was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since , a lava-dome complex, Santiaguito, has been forming in the crater.
Growth of the dome has produced pyroclastic flows as recently as the they can be identified in this image. The city of Quezaltenango approximately 90, people in sits below the m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in , which killed about people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows.
More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. The growth and decay of ocean-island volcanoes are intrinsically linked to vertical movements.
While the causes for subsidence are better understood, uplift mechanisms remain enigmatic. Santa Maria Island in the Azores Archipelago is an ocean-island volcano resting on top of young lithosphere, barely km away from the Mid-Atlantic Ridge.
Like most other Azorean islands, Santa Maria should be experiencing subsidence. Yet, several features indicate an uplift trend instead. The fact that an island located in young lithosphere experienced a pronounced uplift trend is remarkable and raises important questions concerning possible uplift mechanisms.
