What do you mean by seismic waves? How seismic waves have helped in understanding the structure of the earth? (250 W/ 15 M)

Mentor’s Comment:

• Introduction should explain about Seismic waves as it has been the basis of most hypotheses developed on earth’s structure. How it gets generated.
• Further, mention the types and their respective features concerning the earth’s structure. How seismic waves are measured.
• Next, mention how these waves helped in understanding the features of earth. As we know today, that Inner core is solid, outer core is liquid. Also the way waves travel gives ideas regarding properties of material through which it is travelling. It also helps in understanding the earth’s velocity, regions of earth quakes, shadow zones etc.
• Mention conclusion based on the points of main part(s).