AbstractLong waves can be trapped by oceanic ridges due to refraction effect, and such guided waves travel along the ridge and transfer their energy to rather long distance. The guided wave is constrained over the top of the ridge and propagates slower than the free long wave, which leads to the largest amplitude waves arriving later and duration of tsunami activity longer. The existence of trapping effect of ocean ridges has not only been demonstrated mathematically (Buchwald 1969; Zheng et al. 2016), but also been verified by the interpretation of tide-gauge data and numerical models on global tsunami events (Koshimura et al. 2001; Titov et al. 2005).
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Koshimura, S., Imamura, F., and Shuto, N. (2001). "Characteristics of Tsunamis Propagating over Oceanic Ridges: Numerical Simulation of the 1996 Irian Jaya Earthquake Tsunami." Natural Hazards, 24(3), 213-229.
Titov, V., Rabinovich, A. B., Mofjeld, H. O., Thomson, R. E., and González, F. I. (2005). "The Global Reach of the 26 December 2004 Sumatra Tsunami." Science, 309(5743), 2045-2048.
Zheng, J.-h., Xiong, M.-j., and Wang, G. (2016). "Trapping mechanism of submerged ridge on trans-oceanic tsunami propagation." China Ocean Engineering, 30(2), 271-282.