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SUMMARY The eruption of the submarine Hunga Tonga-Hunga Haʻapai (Hunga Tonga) volcano on 15 January 2022, was one of the largest volcanic explosions recorded by modern geophysical instrumentation. The eruption was notable for the broad range of atmospheric wave phenomena it generated and for their unusual coupling with the oceans and solid Earth. The event was recorded worldwide across the Global Seismographic Network (GSN) by seismometers, microbarographs and infrasound sensors. The broad-band instrumentation in the GSN allows us to make high fidelity observations of spheroidal solid Earth normal modes from this event at frequencies near 3.7 and 4.4 mHz. Similar normal mode excitations were reported following the 1991 Pinatubo (Volcanic Explosivity Index of 6) eruption and were predicted, by theory, to arise from the excitation of mesosphere-scale acoustic modes of the atmosphere coupling with the solid Earth. Here, we compare observations for the Hunga Tonga and Pinatubo eruptions and find that both strongly excited the solid Earth normal mode 0S29 (3.72 mHz). However, the mean modal amplitude was roughly 11 times larger for the 2022 Hunga Tonga eruption. Estimates of attenuation (Q) for 0S29 across the GSN from temporal modal decay give Q = 332 ± 101, which is higher than estimates of Q for this mode using earthquake data (Q = 186.9 ± 5). Two microbarographs located at regional distances (<1000 km) to the volcano provide direct observations of the fundamental acoustic mode of the atmosphere. These pressure oscillations, first observed approximately 40 min after the onset of the eruption, are in phase with the seismic Rayleigh wave excitation and are recorded only by microbarographs in proximity (<1500 km) to the eruption. We infer that excitation of fundamental atmospheric modes occurs within a limited area close to the site of the eruption, where they excite select solid Earth fundamental spheroidal modes of similar frequencies that are globally recorded and have a higher apparent Q due to the extended duration of atmospheric oscillations.
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The wave blown around the world
On 15 January 2022, unusual waves appeared in Earth’s atmosphere and oceans ( 1 – 3 ). The origin of the waves was clearly the catastrophic volcanic eruption in Tonga, which pummeled the atmosphere with the largest eruptive plume since the 1883 eruption of Krakatoa, Indonesia. On page 95 of this issue, Matoza et al. ( 4 ) show that the 2022 Tonga eruption generated waves in the water, air, and even in the ionosphere that wrapped around Earth multiple times. Tsunamis appeared to hop across the land into all of the major ocean basins. And on page 91 of this issue, Kubota et al. ( 5 ) explain that the tsunamis arrived much earlier than expected on the basis of conventional tsunami modeling, and the wave trains lasted much longer than for even the largest earthquakes ( 5 ).
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- Award ID(s):
- 1802364
- PAR ID:
- 10412013
- Date Published:
- Journal Name:
- Science
- Volume:
- 377
- Issue:
- 6601
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 30 to 31
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.abq5392
