Frozen lakes end the winter with an 'ice tsunami'

If the winds are strong enough and sustained, the spring can deliver ice shove or ice heave at the edge of lakes in the north of the globe

In late February, the winter ice may start to melt. When that happens, frozen lakes can send spectacular slow-motion waves of crushed ice cascading over the shoreline onto the land. These waves are sometimes called "ice tsunamis" but, to meteorologists, they are "ice shove" or "ice heave".

Specific conditions are needed to produce ice heave. There must be large cracks in the lake ice, which must be separated from the shore, so that it becomes several free-floating sheets. This only occurs when a thaw starts. Then there needs to be a powerful wind blowing in the direction of the shore for at least 12 hours.