The global reach of the 2022 Tonga volcanic eruption

The Tonga volcanic eruption of 15 January 2022 generated tsunami waves that impacted the entire Global Ocean as far away as 18,000 km from the source in the tropical Pacific Ocean. A defining characteristic of the tsunami was the dual forcing mechanism that sent oceanic waves radiating outward from the source at the longwave speed and atmospheric pressure Lamb waves radiating around the globe at the speed of sound (i.e. roughly 1.5 times faster than the longwave phase speed). Based on time series from several hundred high-resolution observational sites, we constructed global maps of the oceanic tsunami waves and the atmospheric Lamb waves. In some areas of the Pacific Ocean, we were able to distinguish between the two types of motions and estimate their relative contribution. A global numerical model of tsunami waves was constructed and results from the model compared with the observations. The modeled and observed tsunami wave heights were in good agreement. The global maps also enabled us to identify regional “hot spots” where the tsunami heights were highest. In addition to areas in the Pacific Ocean (Chile, New Zealand, Japan, the U.S. West Coast, and the Alaska/Aleutian Islands), “hot regions” included the Western Mediterranean and the Atlantic coasts of Europe and northern Africa.