2:00 PM - 2:15 PM
[HDS11-07] Airwave-tsunami source inversion using barometer data for the 2022 Tonga volcanic tsunami
Keywords:Volcanic tsunami, Airwave, Inversion, Tsunami prediction, Hunga Tonga - Hunga Ha'apai
The 2022 Hunga Tonga – Hunga Ha’apai eruption generated atmospheric pressure waves, or airwaves, that were recorded at meteorological stations around the world. This type of wave can effectively trigger tsunamis when propagating over the deep ocean. Airwaves propagate at a speed almost equivalent to the speed of sound (~320 m/s), which is faster than the typical speed of a tsunami (about 200 m/s in water depths of 4 km). By analysing the airwave data, we might obtain a sufficient lead time for an effective tsunami warning. We used airwaves data recorded in New Zealand, Niue, Cook Islands, and Japan for an airwave source inversion. We used airwave data recorded in New Zealand, Niue, the Cook Islands, and Japan for airwave source inversion. The unit source was constructed using a B-spline function characterised by a diameter of 50 km. We simulated synthetic airwaves by solving the long-wave equations, assuming a constant wave speed of 310 m/s. For the source inversion, the time window spanned 3 hours with a total of 30 time-windows and a 90-second shift between each window. We performed the inversion for each station to determine the source time function and then analysed the differences and similarities among the estimates. Overall, all stations suggested that the total source duration is about 30 minutes, while the peak is around 15-20 minutes after the initiation. The estimated source time functions in Niue and Cook Islands are slightly more energetic than those at New Zealand and Japanese stations. We analysed the inversion outcomes to understand the explosion's magnitude and sequence. The source time functions reveal at least four distinct peaks, each corresponding to observed explosions. Furthermore, we investigated whether the inversion result can be used to forecast the tsunami.