1.(6 pts). a) Using the travel-times curves (Figure 3.5-4) for earthquakes at the surface and at a depth of 600 km, estimate the ray parameters in s/degree for direct P waves

at 60° distance. b) Find angles of incidence at the earthquake source for these two rays by converting ray parameter values to s/radian and using the velocities estimated from Figure 3.5-1 (also attached). c) In words and with a sketch, explain how and why the angle of incidence for rays reaching a given distance varies with the depth of the earthquake.