The Birth of a New Island
In late December 2014 into early 2015, a submarine volcano in the South Pacific Kingdom of Tonga erupted, sending a violent stream of steam, ash and rock into the air. When the ash finally settled in January 2015, a newborn island with a 400-foot summit nestled between two older islands – visible to satellites in space.
The newly formed Tongan island, unofficially known as Hunga Tonga-Hunga Ha’apai after its neighbors, was initially projected to last a few months. Now it has a 6- to 30-year lease on life, according to a new NASA study.
Hunga Tonga-Hunga Ha’apai is the first island of this type to erupt and persist in the modern satellite era, it gives scientists an unprecedented view from space of its early life and evolution. The new study offers insight into its longevity and the erosion that shapes new islands. Understanding these processes could also provide insights into similar features in other parts of the solar system, including Mars.
The new island is perched on the north rim of a caldera on top of an underwater volcano that stands nearly 4,600 feet (1,400 meters) above the surrounding the sea floor, according to seaborne bathymetry measurements made by geologist and co-author Vicki Ferrini at the Lamont-Doherty Earth Observatory at Columbia University in Palisades, New York.
Underwater, the base of the new volcanic dome that formed the island extends about 0.6 miles (1 kilometer) from the shoreline into the floor of the larger caldera, which is about three miles (five kilometers) across. In the shallowest part of the survey area closest to the southern side of island, the seafloor levels out into a nearly flat shelf, which is likely important in explaining the pattern of redistribution for the eroded material
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