Mauna Loa, Earth’s largest active volcano, is located on the Island of Hawai‘i and is monitored by the U.S. Geological Survey’s (USGS) Hawaiian Volcano Observatory (HVO).
Mauna Loa erupted most recently in 1984 and will erupt again in the future, posing significant risk to people living on the flanks of the volcano. This geonarrative provides an overview of Mauna Loa’s eruptive history and hazards and includes interactive maps and datasets to help residents prepare for the next eruption (Wright and others, 1992; Trusdell and others, 1996; Wolfe and Morris, 1996; Sherrod and others, 2007; Kauahikaua and others, 2017; Trusdell and Lockwood, 2017; Trusdell and Zoeller, 2017; Trusdell and Lockwood, 2019, 2020).
The Hawaiian Islands exist because of a hot spot beneath the oceanic crustal plate, where magma upwells and erupts at the surface.
As the Pacific Plate drifts northwestward, the hot spot below remains almost stationary, resulting in a chain of islands and atolls called the Hawaiian Ridge-Emperor Seamount volcanic chain. The hot spot is now below the Island of Hawai‘i and Kama‘ehuakanaloa (formerly Lō‘ihi Seamount) to the southeast, and the chain is progressively older and more eroded with increasing distance from the hot spot.
Mauna Loa is on the Island of Hawai‘i—the largest and youngest island in the chain—at the southeastern end of the Hawaiian Islands.