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Caldera Collapse

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Sonar Data Reveals Why Tonga’s 2022 Volcano Collapse Triggered Record Tsunami
science14 days ago

Sonar Data Reveals Why Tonga’s 2022 Volcano Collapse Triggered Record Tsunami

New research published in Nature Geoscience explains why the 2022 Hunga-Tonga eruption produced the largest tsunami ever recorded from an underwater volcano. By comparing rare pre- and post-eruption sonar maps, scientists determined that the volcano’s caldera collapsed as a single, massive block, displacing nearly 9 cubic kilometers of material. This rapid, piston-like subsidence displaced enough ocean water to generate waves up to 40 meters high, challenging previous assumptions that only large volcanic structures could cause such extreme hazards.

Tiny Caldera, Huge Hazards: Rapid Submarine Collapse at Hunga Tonga, 2022
geoscience25 days ago

Tiny Caldera, Huge Hazards: Rapid Submarine Collapse at Hunga Tonga, 2022

Time-series bathymetry shows the 2022 Hunga Tonga eruption caused a rapid, piston-like collapse of a ~4.8 km wide submarine caldera, deepening from ~150 m to ~850 m and displacing ~8.9 km³ (6.85 km³ from caldera collapse; the rest from erosion). Intercalated landslides and inward terraces indicate syn-eruptive, ring-fault–driven subsidence with minor wall collapse. About 7–8 km³ of Dense Rock Equivalent magma drove the collapse (roughly 30 MPa underpressure), suggesting a relatively small reservoir could trigger a large collapse. The eruption generated a record submarine tsunami (~40 m near source). Post-eruption surveys show limited geomorphic change after months, but ongoing shallow magmatic fluids imply continued magmatic activity. Globally, small submarine calderas can produce extreme tsunami hazards, underscoring the need for high-resolution repeat seafloor mapping, improved hazard assessments, and seafloor infrastructure protection.