How do seismic waves scientists understand earth's layers? select the two correct answers.
1.scientists can observe which seismic waves change the composition of the layers they pass through
2.scientists can observe how seismic waves multiply when passing through different layers.
3.scientists can observe how seismic waves change speeds when passing through different layers.
4.scientists can generate seismic waves in order to observe their paths through earth.
5.scientists can observe which seismic waves cannot pass through certain layers.