Gaua (previously called Santa Maria) Island is one of the Banks and Torres group in the northern part of the Vanuatu archipeligo.

Gaua rises about 9,800 feet (3,000 m) from the sea floor. Steaming Hill Lake, a crescent-shaped crater lake, is just below Mt. Garat, a secondary cone and summit of the stratovolcano (a volcano made of both lava flows and pyroclastic <ejected> material) volcano. Solfataras (a type of fumerole, with particularly sulphurous gasses) are on the south side of the volcano and hot springs are on the north slope. Gaua has had at least 13 eruptions from Mt. Garat since 1963. The most recent eruption was in 1982 and lasted less than one day. Most of the historic eruptions have lasted only 1-2 days with the 1963 and 1973-1974 eruptions lasting a few months. Each of these eruptions was small with VEI of about 2 except for the 1965 eruption which had VEI=3. However, from time to time the gases emitted have been poisonous and approaching it is dangerous.

Soritmeat - (Mt. Sere'ama)

At least six volcanic peaks define the spine of Vanua Lava Island. Soretimeat, near the center of the island, is a complex volcano like Vesuvius. Soretimeat has a summit crater about 2,700 feet (900 m) in diameter and 300 feet (100 m) deep which contains a lake. A solfataric (a type of fumerole, with particularly sulphurous gasses) area, called Frenchman's Sulphur Deposit, is on the outer northeast flank of the volcano. Steam, hydrogen sulfide, carbon dioxide, and some sulfur dioxide is released.

Three historic eruptions occurred ca. 1860, ca. 1865, and from 1965-1966. Each of these eruptions was small with VEI of about 2. The two eruptions in the 19th century were from the central vent and were explosive. The most recent eruption was on the northwest flank and was phreatic (when water and heated rocks, not magma, combine to cause an explosive eruption of steam and pulverised rocks).

A sample of basaltic lava from Soretimeat contains crystals of plagioclase, pyroxene, and a little olivine. A chemical analysis of the basalt is: 54.3% SiO2, trace TiO2, 15.2% Fe2O3, 16.3% Al2O3, trace MnO, 8.5% CaO, 1.9% MgO, 3.3% Na2O, and 0.8% K2O

Traitor's Head

A stratovolcano with two historic eruptions. In 1881, the volcano erupted from a submarine vent on the northeast flank. In 1959, an eruption was reported from four submarine vents north of Erromango Island.