How Volcanoes Work

 Image Described in Caption
Mild explosion as lava enters ocean at Kilauea, Hawaii -- Lava entrance into the ocean is often passive; however, this mild explosion resulted from cracking of a lava tube, which allowed water to enter through the fractures where it instantly flashed to steam. Such occurrences result in sporadic bursts of molten dome-shaped lava bubbles. Courtesy of T.J. Takahashi, USGS.