一个覆盖太平洋区域的地震海啸波幅预报系统及检验

基于线性长波方程和缓变地形近岸波幅格林公式建立了覆盖整个太平洋区域的准实时地震海啸波幅预报系统。系统利用了GPU并行加速技术，可在90 s之内完成太平洋区域32 h的海啸传播计算和中国沿海城市岸段的波幅特征值预报。筛选了自2006年以来的9次发生在太平洋区域，矩震级（Mw）超过8.0且资料丰富的历史地震海啸事件，对预报系统进行了后报检验。结果表明，线性长波模型能够很好的模拟海啸在大洋中的传播过程；格林公式能够较为准确的估算缓变水深和开阔地形条件下的近岸海啸最大波幅，波幅预警准确率可达80%，基本满足海啸预警需求。以2011年日本Mw9.0地震海啸为例，评估了该系统对中国城市岸段的波幅预警能力，结论基本合理。需要注意的是，利用该系统计算对海啸源特别敏感的近场海啸波幅可能产生较大偏差。提出了若要进一步提高定量海啸波幅预警的准确率，可从以下两个方面加强研究和业务实践:一是采用多数据联合反演方法提升海啸源的精度；二是提高格林公式的适用性，或者构建高效的近岸精细化海啸数值预报系统。

Development and validation of a tsunami amplitude forecast system covering the whole Pacific Ocean

Based on linear shallow water equation and tsunami amplitude Green''s law, a rapid earthquake induced tsunami amplitude forecast system covering the Pacific Ocean is developed. Thirty-two hour tsunami propagation simulation and amplitude forecast for Chinese coast can be completed within 90 s by using GPU parallel method. The system is validated by 9 major historical tsunamis induced by submarine earthquakes with Mw more than 8.0 in the Pacific region since 2006 with abundant observations. The results indicate that the linear shallow water model is capable of simulating the tsunami propagation in the ocean. And the Green''s law basically can be used for amplitude estimation in the coastal region under the condition of slow-varying topography and open coastline with no complex geometry. Forecasting accuracy of threat levels is acceptable in terms of tsunami warning purpose, with 80% of results falling into the corresponding levels. The evaluation also confirms that the forecasting system can meet the requirement of tsunami warning in Chinese coastal areas. Note that near-field amplitude may have large deviations because of its sensitivity to tsunami source. In order to further improve the accuracy of quantitative warning of tsunami amplitude, we need to strengthen the research and operational practice from the following aspects:one is to improve the precision of the tsunami source by using method of multiple-data joint inversion; the second is to validate the feasibility of Green''s law, or to construct refined and high-efficiency tsunami forecast model in coastal regions.