Atmospheric-Solid Earth Coupling Excites Global Vibrations from the Upper Crust to the Upper Mantle Following the 2022 Hunga Eruption, Tonga.
Abstract
The Hunga volcano (Tonga) eruption of January 15, 2022, one of the largest volcanic explosions recorded by geophysical instrumentation (as measured by pressure wave amplitudes), was also notable for a broad range of atmospheric wave phenomena that it generated. In this presentation, we use the Global Seismographic Network's (GSN) co-located seismometers and pressure sensors to demonstrate two mechanisms by which atmospheric signals caused by the eruption coupled into the solid Earth. First, globally observed, 40 to 90 s period infrasound are shown to have induced ground motion throughout the upper several kilometers of Earth's crust. Ground motions predicted by applying a simple modeling scheme and coarse (CRUST1.0; 1-degree lateral resolution) crustal velocity and density model are broadly consistent with observed ground motions to within a factor of two at many GSN stations. Our results suggest that further analysis of seismic-to-acoustic coupling phenomenon from the eruption can place further constraints on global crustal structure models. Second, we show direct observations that the Hunga eruption excited the fundamental mode of Earth's atmosphere, which then coupled into the solid Earth to produce globally observed 270 s period Rayleigh waves (which are sensitive to upper mantle structure). We show that this coupling mechanism likely occurred over a limited spatial area of less than ~1000 km from Hunga Tonga. Similar 270 s Rayleigh waves were reported following the 1991 Pinatubo eruption but were an order of magnitude smaller in amplitude. The physical reason for this difference is unclear; we speculate that it could be due to differing source processes and/or the regional atmospheric structure for each event.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.P26B..03A