At the edge of a continental shelf, where the depth of the ocean column can vary rapidly by a factor of \(\sim \) 20, tsunamis are expected to be severely refracted in application of Snell’s Law. We use beaming techniques applied to numerical simulations under the shallow-water approximation, in the geometry of two real-life provinces of the Pacific Basin featuring sharp bathymetric discontinuities and extended shelves (Southeastern Alaska and Nicaragua). We conclude that tsunamis do indeed undergo refraction under Snell’s Law with equivalent refraction indices as high as 5. We apply the same technique to actual records of the 2011 Tohoku tsunami by an array of seafloor pressure sensors off the coast of Southern California, and similarly observe Snell refraction despite a smaller velocity contrast and the presence of a shelf with extremely irregular bathymetry. Finally, we show numerically that for a source and a linear array of receivers both deployed on a well developed continental shelf bordering a deep basin, the tsunami will develop a head wave in all ways similar to the familiar case of refraction seismology.

在大陆架的边缘，海洋柱的深度可以迅速变化\（\ sim \）20，海啸预计将在应用斯涅尔定律时发生严重折射。我们使用波束赋形技术将浅水近似值应用到太平洋盆地两个真实存在的省份（以陡峭的测深不连续性和扩展的架子（阿拉斯加东南部和尼加拉瓜））的几何形状中的数值模拟。我们得出的结论是，海啸确实确实在斯涅尔定律下发生了折光，折光率高达5。我们通过南加州沿海的一系列海底压力传感器，对2011年东北海啸的实际记录应用了相同的技术，并进行了类似观察尽管速度反差较小，并且存在具有极不规则的测深仪的架子，但斯涅尔折射仍然存在。最后，