My guess is a large Tesla longitudinal scalar EM energy slug initiating harmonic wave-coupling within the interatomic bonding of the ground rock could cause an earthquake, and a resultant tsunami, like the one that occurred off the coast of Japan not too long ago. The weapon's microsecond wave release of a concentrated EM energy pulse causes an explosive splitting apart of the interatomic-level bonding of the targeted material, such as below-ground rock, in other words, it would create a huge explosion and a earthquake, indistinguishable from a 'normal' earthquake. The explosion could possibly cause a 30 foot wave, or tsunami, or sudden rise in the sea level. Then again I'm probably wrong, and hope I am!