Found that like nuclear fallout, eco shields minimize  if not negate tunami's impact, i had a test game where two islands in direct proximity to geothermal power plants with open coastlines. any off-shore windfarms not within teh shields are set ablaze, like oil rigs, but anything thats shielded will survive and keep on producing even when underwater, at least in my experience, also, trie dto create a break water with pier tiles, tsunami destroyed it instantly, so thats no help, so yeah, shield is, as always, the way to go