magnitude – n. the size of something; the strength of an earthquake's power

interact – v. act in such a way as to have an effect on something or someone else

source – n. a person, place or thing from which something comes

crust – n. hard, outer surface of something

exciting – adj. producing strong feelings

continental shelf – n. an area at the bottom of the sea near the coast of a continent, where the sea is not very deep

phenomenon – n. someone or something that is popular, especially because of an unusual ability or quality

track – v. to follow the progress of something