Volcanoes at Subduction Zones
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
Higher order thinking skills goals for this activity
Other skills goals for this activity
Description of the activity/assignment
The Andean Cordillera extends along the entire western margin of South America; it is part of a longer cordillera stretching from North America through Central America and south to Antarctica. "Cordillera" is a Spanish word adopted by geologists to refer to a large mountain range. These mountains include the highest peak in the Americas: Mt. Aconcagua in Argentina, which rises almost 7000 m (23,000 ft) above sea level. The Andes also contain the mountain peak farthest from the center of the Earth: Chimborazo in Ecuador, located on the equatorial bulge of the planet. In fact, the highest volcanoes in the world are part of the Andean Cordillera as a result of the Nazca and Antarctic Plates subducting beneath western South America.
This activity may be assigned with or without using Google Earth. Student materials for both options include the instruction sheet and an Excel spreadsheet. For the Google Earth option, a .kmz file is available containing information about earthquakes in South America and volcanic arcs around the world. For the option without Google Earth, a PDF contains images of the various arcs (screenshots from Google Earth).
The activity first presents the concept of the uneven distribution of volcanoes in South America and compares it with the distribution of earthquake epicenters. Then, students interpret this information in terms of subduction angle variations along the arc. The rest of the activity involves using Google Earth or screenshots to view other volcanic arcs and measure arc-trench distances. These data are entered into Excel and used to calculate the subduction angles for various arcs. Finally, students interpret a graph of the data.
This activity was designed as part of a longer laboratory exercise that includes more detailed work with the 1980 eruption of Mt. St. Helens, a subduction zone volcano. These other activities may also be found on the SERC website. When all three activites are combined, the laboratory exercise consists of the following:
- Part I: Mt. St. Helens Ashfall Eruption <https://serc.carleton.edu/teachearth/activities/181097.html>
- Part II: Mt. St. Helens Topographic Profiles <https://serc.carleton.edu/NAGTWorkshops/geodesy/activities/204957.html>
- Part III: Volcanoes at Subduction Zones
Determining whether students have met the goals
Teaching materials and tips
- Activity Description/Assignment: Student Instructions for Subduction Zone Activity (Microsoft Word 2007 (.docx) 690kB Jun16 19)
- Instructors Notes: Lecture Slides for Volcanoes Activity (Acrobat (PDF) 9.7MB Jun16 19)
- Student Workbook for Volcanoes Activity (Excel 2007 (.xlsx) 66kB Jun16 19)
- Google Earth file for Volcanoes Activity (KMZ File 130kB Jun16 19)
- Student Handout for Volcanoes Activity (Acrobat (PDF) 38.4MB Jun16 19)
Tilling, R.I., 2009, Volcanism and Associated Hazards: the Andean Perspective: Advances in Geosciences, v. 22, pp. 125-137: Online resource – Accessed 16 June 2019
Subduction Zone Volcanoes, 2017: Annenberg Foundation: Online resource – Accessed 16 June 2019