Mauna Loa (United States)

Status Unrest Eruption 1984 4170m
Shield (Intraplate / Oceanic crust (< 15 km))

Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world's largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al. 1989). Almost 90% of the surface of the basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.

The low-angle slopes of snow-capped Mauna Loa shield volcano give a deceptive perception of the size of the world's largest active volcano. Mauna Loa rises nearly 9 km from the sea floor to an altitude of 4170 m. Mauna Loa's elongated profile was created by repeated eruptions of thin lava flows, primarily from fissure vents along NE- and SW-trending rift zones. Almost 90% of the volcano's surface area consists of lava flows less than 4000 years old.

Photo by Richard Fiske (Smithsonian Institution).

Last updated 2019-08-04 00:28:03