National Park Rift Zone Photograph by J.D. Griggs, U.S. Geological Survey, March 4, 1985. These planar, tabular-shaped intrusions of liquid magma are called dikes. They are also called dikes after the magma solidifies. The intrusion of magma causes the volcano to grow laterally.
Intrusions can also cause cracking at the surface.
This photograph is an aerial view of the southwest rift zone of Kilauea Volcano. The view is to the northeast. Crater Rim Drive is near the top of the slide. The darker lava flows are from the September 1971 eruption. The brown tephra seen within the cracks is from the explosive eruption of 1790.