CNN is reporting that the first small  wave from a tsunami has  hit Hawaii.  It was a metre higher than the normal waves in the area.

The first wave is not necessarily the largest wave.

The tsunami was created by a Chilean earthquake that measured  8.8 on the  Richter scale.

According to the West Coast and Alaska  Tsunami Warning Center, a tsunami is a series of long waves.

It undergoes a transformation as it leaves deep water and moves into shallow coastal areas. Its speed diminishes, but the energy level remains constant, the tsunami-warning center notes.  

"Therefore, the speed of the tsunami decreases as it enters shallower water, and the height of the wave grows," it states.  "Because of this 'shoaling' effect, a tsunami that was imperceptible in deep water may grow to be several feet or more in height."

In deeper waters, its length may be 100 miles or more and it can travel at speeds exceeding 970 kilometres per hour. They can't be seen from the air.