Question

The graph shows how P- and S-waves travel through various depths inside Earth.







Which model of Earth's structure is best supported by the graph?


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Answer 1

The model with a liquid outer core and a solid inner core (solid crust/mantle, liquid outer core, solid inner core).

Reason: S-wave speeds drop to zero at the core–mantle boundary, so S-waves cannot travel through the outer core (it must be liquid). P-waves slow/refract at that boundary but continue and then show an increase in speed again at the inner-core boundary, indicating the inner core is solid.