Home Reef is a submarine volcano in the Tonga archipelago known for its “now you see it, now you don’t” nature. Throughout history, eruptions have repeatedly built small islands that are then eroded away by the ocean. These islands are typically short-lived, lasting from a few months to a few years. The volcano is part of the Tofua volcanic arc. Home Reef’s eruptions often produce dramatic displays, including surges of molten lava, ash plumes, and vast rafts of floating pumice. The most recent eruption, which began on Dec 4 2024, is mostly effusive and continues to expand the small island.
False colour – Sentinel 2 – 7/12/24
Recent Sentinel-2 satellite imagery provides evidence of the ongoing volcanic activity. The data indicates that the newly formed island is not only expanding laterally but also vertically, with the development of an ever increasing cone/dome.
Lateral Growth: Analysis of the imagery reveals that the island currently measures approximately 460 meters in length and 360 meters in width. This represents a slight increase in area compared to observations in November, indicating continued effusion of lava and deposition of volcanic material. The expansion appears to be primarily concentrated along the eastern and western flanks of the island, suggesting that these are the main areas of current effusive activity.
True colour – Sentinel 2 – 7/12/24
Vertical Growth:
Though we can’t be certain without proper observation, previous eruptions have produced dacite lava and pumice. This lava has a high viscosity and tends to form thick, blocky lava flows and/or steep-sided lava domes. The central mound visible on the imagery appears more pronounced and continues to grow upwards. This has implications for the island’s longevity, as a higher elevation increases its resilience to wave erosion and potential submergence.
MODIS continues to record moderate thermal anomalies.
False colour – Sentinel 2 – 7/12/24
Comparison, showing both lateral and vertical island growth
