a geologist is camped 8,000 m from a volcano as it erupts.
a) how much time elapses before the geologist the sound from the eruption? discuss what we are assuming about the propagation of the wave.
b) how much time does it take the seismic waves produced by the eruption to reach the geologist's camp, assuming the waves travel through granite as sound waves do? discuss why the speed of a wave changes when they go through different materials.