Hawaiian power companies prepared for the tsunami by moving vulnerable generation plants offline to avoid a loss of electricity.

Hawaii Electric Co. spokesman Peter Rosegg says generators use distilled water in boilers to make steam for turbines that make the electricity but rely on sea water for cooling the system.

He says a tsunami can cause the water level in the ocean to withdraw in advance of the wave, which could leave those intake pipes high and dry and affect the plant’s operation.

Rosegg says to prevent that, power providers on the islands shifted power generation to other plants that are not in the so-called inundation zone and are less vulnerable to a retreat of water.