An explosion takes place in an underground mine 15 km away from a home located in a vall...

An explosion takes place in an underground mine 15 km away from a home located in a valley where the soil consists of a clay material with Young’s modulus The average density of the soil in that area is How long after the P waves have shaken the home does the sound of the blast finally arrive? (See also Question 13.)

(reference question 13)

A woman wakes up just after 2 AM. Wondering what woke her, she goes to the window and looks around. Noting nothing out of the ordinary, she sits back down on her bed and all of a sudden a loud explosion rattles her window. The next day, she reads that an underground munitions dump exploded about 10 km from her home. She thinks that perhaps she woke up because she experienced a psychic precognition of the explosion. Can you think of a physical explanation for what might have awoken her the few moments before the sound from the blast hit her window? (See Problem 69.)