Printer Friendly

Compare-Contrast-Connect: Volcanoes

NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas

Not all volcanoes are alike. Volcanoes arise from different geological processes. For example, the volcanoes in SF Fig. 7.8 may look similar in shape, but they have very different properties. Mount St. Helens and Mount Fuji (SF Fig. 7.8 A and C) are both located on subduction zones. They are known as composite volcanoes because the lava produced is a composite, or mix, of continental and oceanic crust. Composite volcanoes rarely erupt, but when they do, they erupt explosively.


SF Fig. 7.8. (A) Mount St. Helens, a composite volcano in Washington state

Image courtesy of United States Geological Survey (USGS)

SF Fig. 7.8. (B) Mauna Kea, a volcano on the island of Hawai‘i, Hawai‘i

Image courtesy of Nula666, Wikimedia Commons


SF Fig. 7.8. (C) Mount Fuji, a volcano in Japan

Image courtesy of Fg2, Wikimedia Commons

SF Fig. 7.8. (D) The eruption of the volcano Eyjafjallajökull, Iceland on 17 April 2010

Image courtesy of Árni Friðriksson, Wikimedia Commons

Mauna Kea (SF Fig. 7.8 B) is over a hot spot, which is a spot on the earth’s surface where a hot magma source is very shallow. The Hawaiian Islands, which are located on the middle of the Pacific plate, formed as the plate moved over this hotspot. Mauna Kea is a dormant volcano. Kīlauea, another volcano on the island of Hawai‘i, is currently active. It is one of the longest continuously erupting volcanoes and usually produces a slow, gentle flow of lava. Iceland, which has a number of volcanoes (e.g., SF Fig. 7.8 D), is a very unusual volcanic landmass because it is formed where the mid-ocean rift actually rises above the surface of the water. Eyjafjallajökull and Mt. Saint Helens are composite volcanoes, which are typically steep and produce explosive eruptions. In SF Fig 7.8, you see an eruption of Eyjafjallajökull (SF Fig 7.8D) and the aftermath of an explosive eruption on Mt. Saint Helens (SF Fig 7.8 A).


Question Set
  1. Locate the volcanoes in SF Fig. 7.8 on a map. On what plate boundaries, or within what plates, are these volcanoes located?
  2. Why do you think hot spot volcanoes have a different type of eruption pattern than volcanoes on subduction zones? Explain your answer in terms of plate movement. (Hint: Research the composition of the magma and lava.)
  3. Research what volcanic eruptions in Iceland are like. Compare their eruptions to those of volcanoes at subduction zones or on hot spots. How are they similar? Different?
  4. Which of the volcanoes in SF Fig. 7.8 are currently erupting? When do scientists predict these eruptions will stop?
  5. Which of the volcanoes in SF Fig. 7.8 are active, but not currently erupting? When do scientists think they will erupt again?
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.