An undersea volcano Hunga Tonga-Hunga Ha'apai, located about 60 km (40 miles) north of Tongatapu, Tonga began erupting in late December 2014. On January 6, 2015, Wellington VAAC said observed volcanic ash is reaching an altitude of 6 km.
The two small volcanic islands of Hunga Tonga and Hunga Ha'apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of the rim of a largely submarine caldera lying east and south of the islands.
Hunga Tonga and Hunga Ha'apai reach an elevation of only 149 m and 128 m above sea level, respectively, and display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera.
Several submarine eruptions have occurred at Hunga Tonga-Hunga Ha'apai since the first historical eruption in 1912, according to GVP.
Its last reported eruption occurred in 2009.
The new eruption seems to be occurring just offshore of Hunga Ha'apai. It was first reported by fisherman who came back from the area on December 19, 2014.
Image credit: Wellington VAAC
The following, natural-color, images from December 29 and 31, 2014, show the waters around Tonga, Hunga Tonga, and Hunga Ha'apai, as observed on by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.
Image credit: NASA Terra/MODIS. Acquired December 29, 2014.
Image credit: NASA Aqua/MODIS. Acquired December 30, 2014.
A white plume rises into the sky on both days. The discolored water nearby suggests an underwater release of gases and rock or the disturbance of sediment by the eruption.
Featured image: Undersea eruption of Hunga Tonga-Hunga Ha'apai on December 30, 2014. Credit: NASA Aqua/MODIS