Question: Which of the following describes the movement and size of a tsunami? Need Assignment Help? Initially, it is shallow, but fast and wide. As it reaches the shoreline, it It is wide and fast from the time it is created until it hits the slows down but gets taller. shoreline. Initially it is small and slow. As it reaches the shorelines, it grows in It starts as tall, slow waves, then increases in width and speed as it size and speed. joins with other waves. It is initially quite narrow and slow, but then becomes wide and fast.