#COMET DEEP OCEAN WAVES CODE#

Critically, acoustic-gravity waves propagating over the ocean can force the sea surface to generate tsunami-like waves, known as volcano-meteorological tsunamis 4, 7. Acoustic-gravity waves propagate into different media, becoming hydroacoustic (in water), Scholte (in seabed) or Rayleigh–Lamb (in elastic layers) 17, 18. As such, they can travel substantial distances before dissipating 14. Acoustic-gravity waves are low-frequency compression-type sound waves propagating under gravity at speeds close to those of the sound of the medium (for example, about 340 m s −1 in air and 1,500 m s −1 in water) 16. If the explosive pressure is sufficiently large, the thrusting of volcanic products into the atmosphere can produce acoustic-gravity waves 15. Violent explosive eruptions may trigger atmospheric perturbations by a sudden ejection, at supersonic speeds, of lava and gases into the air 14. However, the generation of interoceanic volcanic tsunamis, although rare, is possible through air–water coupling 9, as illustrated by the approximately CE200 Taupō (New Zealand) 8, the 1883 Krakatau (Indonesia) 1, 5, 10– 12 and the 1956 Bezymianny (Kamchatka) 13 eruptions and associated tsunamis. Consequently, they trigger localized point-sourced tsunamis that dissipate energy very efficiently with distance. Typically, most of these mechanisms do not displace enough water to result in long and far-reaching tsunamis. Volcanic activity has long been recognized as a source of tsunamis, with volcanic earthquakes, gravitational and caldera collapses, pyroclastic flows, underwater explosions and volcanic blasts constituting the main triggers of volcanic tsunami waves 3, 4. This coupling mechanism has clear hazard implications, as it leads to higher waves along land masses that rise abruptly from long stretches of deep ocean waters.

Our models also show that the unusually fast travel times and long duration of the tsunami, as well as its global reach, are consistent with an air–water-coupled source. A direct correlation between the tsunami and the acoustic-gravity waves’ arrival times confirms that these phenomena are closely linked. Here we use sea-level, atmospheric and satellite data from across the globe, along with numerical and analytical models, to demonstrate that this tsunami was driven by a constantly moving source in which the acoustic-gravity waves radiating from the eruption excite the ocean and transfer energy into it by means of resonance. The colossal eruption of the Hunga Tonga–Hunga Ha’apai volcano and ensuing tsunami is the first global volcano-triggered tsunami recorded by modern, worldwide dense instrumentation, thus providing a unique opportunity to investigate the role of air–water-coupling processes in tsunami generation and propagation. Violent volcanic explosions, however, can cause global tsunamis 1, 5 by triggering acoustic-gravity waves 6– 8 that excite the atmosphere–ocean interface. These mechanisms rarely displace enough water to trigger transoceanic tsunamis. Volcanoes can produce tsunamis by means of earthquakes, caldera and flank collapses, pyroclastic flows or underwater explosions 1– 4. Figure maps were produced with the Generic Mapping Tools (GMT) 40 and the Python libraries cartopy and matplotlib. The codes related to the analytical solutions are available on request from the corresponding author. The satellite-data-processing scripts are available at the following public repository ( ).

#COMET DEEP OCEAN WAVES CODE#

The Coupled GeoClaw-atmospheric air-pressure code is available on request from the corresponding author. The tsunami numerical code GeoClaw is available on the Clawpack website ( ). Bathymetric/topographic data are available at the General Bathymetric Chart of the Oceans (GEBCO) ( ). Air-pressure data are available at the Center for Operational Oceanographic Products and Services of the National Oceanic and Atmospheric Administration (NOAA) ( ) and at IPMA ( ). DART buoys and US coastal tide-gauge records are available at the Center for Operational Oceanographic Products and Services of the National Oceanic and Atmospheric Administration (NOAA) ( ). Sea-level datasets are available at the Intergovernmental Oceanographic Commission (IOC) of UNESCO in its Sea Level Station Monitoring Facility ( ).

Optical satellite imagery was collected by the NASA Applied Sciences Program and are publicly available at. GOES-16 and GOES-17 satellite imagery data are available at.

Comet deep ocean waves