Review on Recent Progress in Near-Field Tsunami Forecasting Using Offshore Tsunami Measurements: Source Inversion and Data Assimilation

Abstract

Traditional tsunami forecasting methods are based on seismic observations. The development of offshore observational devices makes it possible to utilize offshore tsunami measurements for providing early warnings. This paper reviews the tsunami data-oriented forecasting methods of two main types: tsunami source inversion and tsunami data assimilation. In the first type, offshore tsunami measurements are used to enhance and speed up the traditional tsunami source inversion methods. The effectiveness and uncertainties of the tsunami source estimation are discussed. In the second type, tsunami data assimilation, the wavefield is directly reconstructed and forecasted without considering the source. We review the techniques that are adopted to improve the speed and accuracy of data assimilation and to determine the optimal design for an ocean bottom pressure gauge (OBPG) network. It is important for tsunami data-oriented forecasting methods to accurately extract tsunami signal in real time, particularly when the OBPG is located inside the source area.

Sequential Bayesian Update to Detect the Most Likely Tsunami Scenario Using Observational Wave Sequences

“…Nevertheless, in situ wave data have the potential to contribute to minimizing such uncertainties since they directly reflect information about occurring tsunamis, as argued by Wang et al. (2021). A similar idea is already employed in the current tsunami warning system in Japan, which relies on a database of precalculated and stored tsunami simulations for various possible earthquake scenarios.…”

Real‐Time Prediction of Alongshore Near‐Field Tsunami Runup Distribution From Heterogeneous Earthquake Slip Distribution

“…Recent progress in the first step of tsunami forecasting can be found in Tsushima and Ohta (2014) and Wang, Tsushima, et al. (2021).…”

“…Instead of inferring earthquake information, some studies suggest methods to directly estimate the tsunami's initial free-surface displacement from the observations without any assumptions about the earthquake (Tsushima et al, 2009(Tsushima et al, , 2011(Tsushima et al, , 2012Saito et al, 2010). Recent progress in the first step of tsunami forecasting can be found in and Wang, Tsushima, et al (2021).…”

Data Assimilation Using High‐Frequency Radar for Tsunami Early Warning: A Case Study of the 2022 Tonga Volcanic Tsunami

“…It directly uses offshore observations to reconstruct the tsunami wavefield and does not require tsunami source information for forecasting. Therefore, it is applicable to tsunamis generated by various sources, such as earthquakes, landslides, and volcanic eruptions (Gusman et al., 2016; Wang et al., 2021). Offshore tsunami observations are primarily provided by offshore bottom pressure gauges (OBPGs).…”