Mauna Loa

Mauna Loa. It is one of five volcanoes that form the Island of Hawaiʻi in the U.S. state of Hawaii in the Pacific Ocean. The largest subaerial volcano in both mass and volume, it has historically been considered the largest volcano on Earth, a title it shares with its neighbor, Mauna Kea. Mauna Loa is an active shield volcano with relatively gentle slopes, built by countless flows of basaltic lava, and is a primary feature of Hawaiʻi Volcanoes National Park.

Geography and geology

Mauna Loa encompasses over half of the land area of the Island of Hawaiʻi. Its summit caldera, Mokuʻāweoweo, measures approximately 5 by 2.5 kilometers and is dotted with pit craters. The volcano's flanks are characterized by two primary rift zones extending northeast and southwest from the summit, which are the source of most historical eruptions. Geologically, it is a classic example of a hotspot volcano, formed as the Pacific Plate moves over a stationary mantle plume, with its oldest exposed rocks dated to around 1 million years. The composition of its lavas is predominantly tholeiitic basalt, typical of the Hawaiian–Emperor seamount chain.

Eruptive history

The documented eruptive history of Mauna Loa extends back to 1843, with well over 30 confirmed eruptions since then, making it one of the most frequently active volcanoes in the world. Notable eruptions include the 1859 event that sent lava flows to the coast near Kiholo Bay, the 1950 eruption which was one of the most voluminous in recorded history, and the 1984 eruption that threatened the city of Hilo. Its most recent eruption occurred in late 2022, ending a 38-year period of quiescence, with lava flows confined to the summit region within Hawaiʻi Volcanoes National Park. Prior to written records, extensive geologic mapping reveals a long history of voluminous eruptions and significant flank collapses.

Monitoring and research

Mauna Loa is closely monitored by the United States Geological Survey's Hawaiian Volcano Observatory, established in 1912 following a devastating eruption on Kīlauea. The observatory employs a comprehensive network of instruments including seismometers, tiltmeters, GPS stations, and gas sensors to detect magma movement and ground deformation. The volcano's slopes are also home to the Mauna Loa Observatory, a premier atmospheric research facility operated by the National Oceanic and Atmospheric Administration, famous for its continuous measurements of atmospheric carbon dioxide since 1958, known as the Keeling Curve.

Human impact and cultural significance

Eruptions have repeatedly impacted infrastructure, destroying villages, roads, and historically threatening the Hilo harbor. The 1950 eruption overran portions of the Saddle Road. In Hawaiian culture, the volcano is considered the physical manifestation of the deity Pele. The regions on its slopes are important for agriculture, including coffee farms in the Kaʻū district and macadamia nut orchards. The volcano's presence is a central part of the identity of the Hawaiian Islands and a major draw for Hawaiʻi Volcanoes National Park, attracting scientists and tourists from around the globe.

Comparison with other volcanoes

While often compared to its neighbor Mauna Kea, Mauna Loa is more voluminous and active. Globally, it is dwarfed in volume by the submarine Tamu Massif in the Pacific Ocean. Among active shield volcanoes, it is more frequently eruptive than Piton de la Fournaise on Réunion island but less so than the persistently active Kīlauea. Its gentle profile contrasts sharply with the steep stratovolcanoes of the Pacific Ring of Fire, such as Mount Fuji in Japan or Mount St. Helens in the United States. Its role in atmospheric science at the Mauna Loa Observatory is unique among the world's volcanoes.

Category:Volcanoes of Hawaii Category:Hawaiian–Emperor seamount chain Category:Shield volcanoes of the United States