Near-field tsunami forecasting from cabled ocean bottom pressure data
Near-field tsunami forecasting from cabled ocean bottom pressure data
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DOI：
10.1029/2008jb005988
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发表时间：
2009-06
影响因子：
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通讯作者：
H. Tsushima;R. Hino;H. Fujimoto;Y. Tanioka;F. Imamura
中科院分区：
文献类型：
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作者：
H. Tsushima;R. Hino;H. Fujimoto;Y. Tanioka;F. Imamura
[1]提出了一种利用海底电缆海啸仪（OBTM）真实的实时数据进行近场海啸预报的方法。我们首先反转记录在OBTMs的海啸波形，以估计在海啸源区的初始海面位移的空间分布，而不作任何假设的断层几何形状和地震震级。然后，我们合成的海岸海啸波形从估计的海面位移分布。为了提高海啸预测的可靠性，我们使用更新的OBTM数据，以1分钟的间隔重复预测计算。我们通过模拟1896年三陆海啸地震来测试我们的方法，该地震导致了日本东北部太平洋沿岸最大爬升高度为沿着38 m的毁灭性海啸。代替真实的OBTM记录，使用代理。模拟结果表明，我们的方法提供了准确的估计海岸到达时间和振幅的第一个峰值的海啸超过20分钟前，最大振幅波到达海岸站点最近的源。我们还将该方法应用于当地地震引起的小海啸的真实的数据，并成功地预测了海啸在沿海潮汐站。我们发现，我们估计的沿海海啸振幅的准确性会受到海啸源和近海观测站之间的空间关系。我们的数值模拟表明，通过部署额外的离岸站，可以实现更准确的海啸振幅预报，这些离岸站之间的距离与海啸源的海沟平行长度相当。
[1] We propose a method for near-field tsunami forecasting from data acquired by cabled offshore ocean bottom tsunami meters (OBTMs) in real time. We first invert tsunami waveforms recorded at OBTMs to estimate the spatial distribution of initial sea-surface displacements in the tsunami source region without making any assumptions about fault geometry and earthquake magnitude. Then, we synthesize the coastal tsunami waveforms from the estimated sea-surface displacement distribution. To improve the reliability of the tsunami forecasting, we use updated OBTM data to repeat the forecast calculation at 1-min intervals. We tested our method by simulating the 1896 Sanriku tsunami earthquake, which caused a devastating tsunami with maximum runup height of 38 m along the Pacific coast of northeastern Japan. Instead of real OBTM records, proxies were used. The simulation demonstrated that our method provided accurate estimations of coastal arrival times and amplitudes of the first peak of the tsunami more than 20 min before the maximum amplitude wave reached the coastal site nearest to the source. We also applied the method to real data of a small tsunami that was caused by a local earthquake and successfully forecasted the tsunami at coastal tide stations. We found that accuracy of our estimated coastal tsunami amplitudes can be affected by the spatial relationship between the tsunami source and the offshore observation stations. Our numerical simulation showed that even more accurate tsunami amplitude forecasts would be achieved by deployment of additional offshore stations separated by a distance comparable to the trench-parallel length of the tsunami source.