Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the correct order to form a meaningful and coherent paragraph.
A. These are generated by a violent undersea disturbance or ocean activity.
B. Once generated, they travel outward on the ocean surface in all directions.
C. A tsunami is made up of a series of very long waves.
D. Spreading thus, they look like ripples caused by throwing a rock in a pond.