Tonga sits astride the Tonga Trench, where the Pacific Plate plunges beneath the Australian Plate at one of the fastest subduction rates on Earth. This intense convergence makes the kingdom exceptionally active, generating deep, powerful earthquakes and a submarine volcanic arc studded with active vents.
In 2022 the eruption of Hunga Tonga–Hunga Haʻapai became one of the most explosive volcanic events in modern history, sending an ash plume into the mesosphere and triggering a tsunami and pressure wave felt around the globe. Large offshore earthquakes are frequent, and the region's tsunami hazard keeps Tonga among the world's most closely watched geological hotspots.