2.13, 3.1

I'm making posts really early, 'cause I'll be gone all weekend...

This section felt a lot like 2.11, there was a good bit of algebra to derive some wave behavior. I understood it better than 2.11 though. I was kind of curious about Love waves - is it possible to give a quick hand-wavy explanation of them like you did with the Raleigh waves (which, I think, did help in understanding the section)? On a more practical note, I'm a little bit curious about what happens around the depth where the retrograde motion turns into prograde motion. It seems like there might be some interesting phenomena there, once some of the terms cancel out and we can see the effects of things we'd neglected elsewhere, but I'm not really sure.

3.1

Phew, I think I'm getting better at understanding this tensor algebra stuff! It's getting quicker to read these types of sections, though it still takes some time to get through it all. One part that I wasn't able to figure out though was the note about 'effective pressure'. It seemed like a silly trick that didn't give me anything useful; did I miss something, is there some physical meaning to it that's good to know or some way in which it needs to be used?