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

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.