The Powers Caldera is a buried summit caldera of Kīlauea on the Big Island of Hawaii. It is the precursor to the modern but smaller Kīlauea Caldera, having formed about 2,200 years ago as a result of powerful phreatomagmatic eruptions. These explosive eruptions lasted for a period of about 1,200 years, during which time the Uwēkahuna Ash Member was deposited. Sometime between 850 and 950 CE, the most powerful explosive eruption sent rocks weighing at least from the summit. Golf ball-sized rocks fell at the coast, away.