Submarine Lava Lakes

Submarine lava lakes result from the rapid eruption of very hot and fluid lava along mid-ocean ridges. They were first discovered on the Galapagos Ridge and East Pacific Rise in the late 1970s. Both of these ridges also have fast spreading rates, approximately four inches (10 cm) per year.

In 1994, an international team discovered two extensive lava lakes on the mid-Atlantic ridge. Unlike the other ridges, the mid-Atlantic ridge spreads at a slower rate, about 2 inches (5 cm) cm per year. The team planned to use their discovery to learn more about the magmatic and hydrothermal systems beneath slow-spreading centers.

Dives were made on two topographic highs along the Mid-Atlantic Ridge near the Azore hot spot. At Lucky Strike (37.3N) the lava lake is 1,000 feet (300m) in diameter and is in the bottom of a 0.6 mile (1 km) diameter caldera. The lava lake is encircled by the largest (0.4 square mile, 1 square km) hydrothermal vent field on the Mid-Atlantic Ridge. At Menez Gwen (37.8N) the lava lake is about 1,200 by 4,700 feet (0.4 by 1.4 km) in diameter and centered in a graben along the crest of the ridge. The hydrothermal field is 0.6 miles (1 km) north of the lava lake near a 650 feet (200 m) high volcano.

The lava lakes are produced by rapid outpourings of lava. The scientific team suggests a shallow magma chamber must be located beneath the axis of the ridge. The shallow magma chamber can produce the rapid outpourings of lava to make the lava lakes.

The discovery also shows that the additional heat of the nearby hot spot is needed to have rapid outpourings of lava and lava lakes in areas where spreading is slow. Away from the influence of the hot spot, topographically high areas with hydrothermal deposits do not have lava lakes.

Summary by Steve Mattox based on Fouquet, Y., Ondreas, H., Charlou, J.L., Donval, J.P., Radford-Knoery, J., Costa, I., Lourenco, N., and Tivey, M.K., 1995, Atlantic lava lakes and hot vents, Nature, v. 377, p. 210.

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