Current is the ultimate after effect of the tsunami. The plates that make up the earth’s crust, push each other hard enough to cause an underwater earthquake; one plate moves upward, and the other moves downward, with such force, that a huge amount of water is displaced, and has to go somewhere.  This displacement causes the water to explode outward in all directions.  As the water moves forward it carries an intensity that is hard to identify.  There is no one huge wave of significant height, getting ever taller and more fierce.  The fierceness is there and the tsunami moves with great speed UNTIL it meets with shallow water, close to land masses.  At this point, the wave rises upward and becomes a virtual wall (sometimes 100 miles long or more) and rises to great heights.   The shock effect against the shore is so horrific that the water recedes completely for a brief moment.  The receding factor is one of the few signs of an oncoming tsunami.  Seconds later the monster wall of water is killing, destroying and tearing apart anything in its path.