Global water level variability observed after the Hunga Tonga-Hunga Ha'apaivolcanic tsunami of 2022

The eruption of the Hunga Tonga-Hunga Ha'apai volcano on 15 January 2022 provided a rare opportunity to understand global tsunamiimpacts of explosive volcanism and to evaluate future hazards, includingdangers from "volcanic meteotsunamis" (VMTs) induced by the atmosphericshock waves that followed the eruption. The propagation of the volcanic andmarine tsunamis was analyzed using globally distributed 1 min measurementsof air pressure and water level (WL) (from both tide gauges and deep-waterbuoys). The marine tsunami propagated primarily throughout the Pacific,reaching nearly 2 m at some locations, though most Pacific locationsrecorded maximums lower than 1 m. However, the VMT resulting from theatmospheric shock wave arrived before the marine tsunami and propagatedglobally, producing water level perturbations in the Indian Ocean, theMediterranean, and the Caribbean. The resulting water level response of manyPacific Rim gauges was amplified, likely related to wave interaction withbathymetry. The meteotsunami repeatedly boosted tsunami wave energy as itcircled the planet several times. In some locations, the VMT was amplifiedby as much as 35-fold relative to the inverse barometer due to near-Proudmanresonance and topographic effects. Thus, a meteotsunami from a largereruption (such as the Krakatoa eruption of 1883) could yield atmosphericpressure changes of 10 to 30 mb, yielding a 3-10 m near-field tsunami thatwould occur in advance of (usually) larger marine tsunami waves, posingadditional hazards to local populations. Present tsunami warning systems donot consider this threat.