the magma that erupts from mauna loa likely formed at hawaii hotspot.
the magma that erupts from mauna loa likely formed at hawaii hotspot.
where did the magma that erupts from mauna loa likely form?
hawaii hotspot
mauna loa has probably been erupting for at least 700,000 years, and may have emerged above sea level about 400,000 years ago. the oldest-known dated rocks are not older than 200,000 years. the volcano's magma comes from the hawaii hotspot, which has been responsible for the creation of the hawaiian island chain over tens of millions of years. the slow drift of the pacific plate will eventually carry mauna loa away from the hotspot within 500,000 to one million years from now, at which point it will become extinct.
mauna loa
because kīlauea lacks a topographical prominence and appears as a bulge on the southeastern flank of mauna loa, it was historically interpreted by both native hawaiians and early geologists to be an active satellite of mauna loa. however, analysis of the chemical composition of lavas from the two volcanoes show that they have separate magma chambers, and are thus distinct. nonetheless, their proximity has led to a historical trend in which high activity at one volcano roughly coincides with low activity at the other. when kīlauea lay dormant between 1934 and 1952, mauna loa became active, and when the latter remained quiet from 1952 to 1974, the reverse was true. this is not always the case; the 1984 eruption of mauna loa started during an eruption at kīlauea, but had no discernible effect on the kīlauea eruption, and the ongoing inflation of mauna loa's summit, indicative of a future eruption, began the same day as new lava flows at kīlauea's puʻu ʻōʻō crater. geologists have suggested that "pulses" of magma entering mauna loa's deeper magma system may have increased pressure inside kīlauea and triggered the concurrent eruptions.
mauna loa