Kilauea (; Hawaiian: ) is a currently active
shield volcano in the
Hawaiian Islands, and the most
active of the five volcanoes that together form the island of
Hawaii. Located along the southern shore of the island, the volcano is between 300,000 and 600,000 years old and emerged above sea level about 100,000 years ago. It is the second youngest product of the
Hawaiian hotspot and the current eruptive center of the
Hawaiian–Emperor seamount chain. Because it lacks
topographic prominence and its activities historically coincided with those of
Mauna Loa, Kilauea was once thought to be a satellite of its much larger neighbor. Structurally, Kilauea has a large, fairly recently formed
caldera at its summit and two active
rift zones, one extending east and the other west, as an active
fault of unknown depth moving vertically an average of per year.