The Tonga Geological Services reported continuing activity at Home Reef. Satellite imagery from 4 April captured a series of small low-level ash plumes generated by explosions. Surface changes at the vent, including new tephra deposits and lava textures, were identified in a 5 April satellite image. A satellite image from 11 April indicated that the vent had the same dimensions as previously reported, 125 m N-S and 110 m W-E. The dome in the vent had grown, mainly to the SW, and spalled or ejected material that rolled down to the shoreline. In both 11 and 26 April images steam plumes rose from the vent and water around the island was discolored. Moderate thermal anomalies were detected by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system during 8-28 April. A sulfur dioxide emission was identified in a 22 April satellite image. Ash emissions were visible in satellite data at around 1400 on 26 April, prompting Tonga Geological Services to raise the Aviation Color Code to Orange (the second highest level on a four-level scale) that same day. According to the Wellington VAAC intermittent, low-level ash plumes were visible in satellite images during 26-27 and 29 April rising 0.9-1.2 km (3,000-4,000 ft) a.s.l. and drifting W and NW. The Maritime Alert Level remained at Orange (the third level on a four-level scale), and mariners were advised to stay at least 2 nautical miles (3.7 km) away from the island. The Alert Level for residents of Vava’u and Ha’apai remained at Green (the first level on a four-level scale).

Geological Summary. Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, large amounts of floating pumice, and an ephemeral 500 x 1,500 m island, with cliffs 30-50 m high that enclosed a water-filled crater. In 2006 an island-forming eruption produced widespread dacitic pumice rafts that drifted as far as Australia. Another island was built during a September-October 2022 eruption.

Sources: Tonga Geological Services, Government of Tonga, Wellington Volcanic Ash Advisory Center (VAAC)