Serway & Jewett — Wave Motion: Problem 50

Tsunamis are ocean surface waves that have enormous wavelengths (100 to 200 km), and the propagation speed for these waves is \( v \approx \sqrt{gd_{\text{avg}}} \), where \( d_{\text{avg}} \) is the average depth of the water. An earthquake on the ocean floor in the Gulf of Alaska produces a tsunami that reaches Hilo, Hawaii, 4 450 km away, in a time interval of 5.88 h. (This method was used in 1856 to estimate the average depth of the Pacific Ocean long before soundings were made to give a direct determination.) Why is the following situation impossible?