Loihi: Hawaii's
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  Above: A 3-man research submarine, the DSV Sea Cliff, is transported on the stern of its mother ship, the Maxine D. Below: The Sea Cliff being launched for a dive. (Photographs by Daniel Fornari, Lamont-Doherty Geological Observatory of Columbia University.) |
If the hot-spot theory is correct, the next volcano in the Hawaiian chain should
form east or south of the Big Island. Abundant evidence indicates that such a new
volcano exists at Loihi, a seamount (or submarine peak) located about 20 miles
off the south coast of the Big Island. Loihi rises 10,100 feet above the ocean
floor to within 3,100 feet of the water surface. Recent detailed mapping shows
Loihi to be similar in form to Kilauea and Mauna Loa. Its relatively flat summit
apparently contains a caldera about 3 miles across; two distinct ridges radiating
from the summit are probably rift zones.
Photographs taken by deep-sea camera show that Loihi's summit area has fresh-appearing, coherent pillow-lava flows and talus blocks. Examination of samples dredged from Loihi indicates that the pillow-lava fragments have fresh glassy crusts, indicative of their recent formation. The exact ages of the sampled Loihi flows are not yet known, but certainly some cannot be more than a few hundred years old. In fact, the occurrence of earthquake swarms at Loihi during 1971- 1972, 1975, and 1984-85 suggests major submarine eruptions or magma intrusions into the upper part of Loihi. Thus, Loihi appears to be a historically active, but as yet submarine, volcano. |
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Updated 05.01.97