## Essential University Physics: Volume 1 (3rd Edition)

As we know that velocity of tsunami for depth d is $v=\sqrt{gd}=450\frac{Km}{h}$ so velocity of tsunami for depth 2d is $v^{\prime}=\sqrt{2gd}$ $\implies v^{\prime}=\sqrt{2} \space gd$ $\implies v^{\prime}=\sqrt{2}\times 450\approx 640\frac{Km}{h}$