View to the northwest across Kilauea Caldera. Halemaumau pit crater is in the center of the photo. Photograph by Peggy Lim and courtesy of U.S. Geological Survey.

Calderas dominate the summits of Kilauea and Mauna Loa volcanoes. The rift zones of these volcanoes are marked by the presence of pit craters. This lesson describes how these features form and the path that magma follows from its source to the surface.

Lesson at a glance, Key Concepts, and Lesson Outcomes are available by clicking here.

Click here for a list of references about MAGMA PATHWAYS, CALDERAS, AND PIT CRATERS.

Click here for a list of activities about volcanic landforms.


The background begins with a description of how magma gets from its point of origin to the surface. As magma accumulates in a shallow reservoir near the summit, it exerts more and more force on the surrounding rocks. If the weight of the rocks pushing down is greater than the force of the magma pushing up, the summit can collapse to produce a caldera. The background concludes with a description of how craters form.

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