Home Reef volcano grows to 6 hectares (15 acres), Tonga

Home Reef volcano re-emerged above sea level on September 9, 2022, prompting authorities in Tonga to issue a Hazard Alert to all marines to sail at least 5 km (3.1 miles) away from the volcano. The volcano is located midway between Metis Shoal and Late Island in the central Tonga islands. It was first reported active in the mid-19^th century when an ephemeral island formed.

In 24 hours to 21:00 UTC on October 3, the Tonga Geological Services recorded a total of 16 eruptions, compared to 9 eruptions in the prior 24 hours.¹

Volcano activity is progressive, with the last eruption recorded at 13:29 UTC on October 3.

The recent eruptions were dominantly steam with no volcanic ash detected in the last 24 hours.

On September 9, the volcano formed a land area of about 0.40 ha (1 acre) a.s.l. with a diameter of 70 m (230 feet) and an estimated elevation of 10 m (33 feet) a.s.l.²

At 21:40 UTC on September 28, the volcano was measured at 268 m (879 feet) North-South and 283 m (9288 feet) East-West, with an approximate total surface area of 6 hectares (15 acres) and an estimated height of 15 to 18 m (49 – 59 feet) above sea level.

Volcanic plume continues to disperse from the island carried by the ocean currents. The plume causes discoloration of the water and it is thickest within 1 km (0.6 miles) of the volcano and thinner within 2 km (1.2 miles) from the island.

The island has steep headlands on the eastern half and a smoother slope on the western half.

There is no risk to communities in Vava’u and Ha’apai.

All mariners are advised to sail beyond 4 km (2.5 miles) from the volcano until further notice.

The video below shows Planet’s high-resolution satellite images compiled to create a movie of Home Reef’s evolution from June to September 2022.

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-19^th century when an ephemeral island formed.

An eruption in 1984 produced a 12 km (39 370 feet) high eruption plume, copious amounts of floating pumice, and an ephemeral island 500 x 1 500 m (1 640 x 4 900 feet) wide, with cliffs 30 – 50 m (98 – 164 feet) high that enclosed a water-filled crater.

Another island-forming eruption in 2006 produced widespread dacitic pumice rafts that reached as far as Australia.³

References:

¹ Public notice on Home Reef volcano activity #23 – Volcano Watch Team of the Tonga Geological Services of the Ministry of Lands and Natural Resources – October 3, 2022

² Home Reef volcano re-emerges above sea level, Tonga – The Watchers – September 14, 2022

³ Home Reef – Geological summary – GVP

Featured image: Home Reef volcano eruption on September 9, 2022. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers (True Color)