Contents of 8.3 How do we know ... how to determine velocities of seismic waves in rocks?

8.3 How do we know ... how to determine velocities of seismic waves in rocks?

The measures of velocity tell geologists that there are differences within Earth
As these occur out of sight, experimentation must be used to deduce the details.
Variations of rock type, temperature, and pressure are the primary variables in these experiments to measure in the lab and then extrapolate to Earth itself.