Energy and Attenuation

Question 1

what is the relationship between frequency and energy?

Answer 1

high frequency, high energy

Question 2

what is the total energy of the wave?

Answer 2

A^2w^2p/2 where a is amplitude, w is freq, and p is density

Question 3

what is the signifcance of geometrical spreading?

Answer 3

the energy summed across the surface of the sphere around the source is always constant, this is why amplitude decays in relation to 1/r^2. (ONLY FOR HOMOGENOUS, PERFECTLY ELASTIC)

Question 4

what is anelastic/intrinsic attenuation?

Answer 4

energy lost by inelastic material behaviour, friction, heat, etc.

Question 5

what is the quality factor Q and what does it represent?

Answer 5

essentially its damping for soil, parameter related to energy loss per cycle Q = 2 pi (E/dE)
amplitude decay is bounded by A = Ao exp(-wt/2Q)

Question 6

is attenuation higher or lower in newer layers of crust?

Answer 6

higher (like in oceanic ridge)

Question 7

what is scattering?

Answer 7

energy loss due to inhomogenous structure of soil at a much smaller scale than the wavelength in question. the same as light scattering in fog for example.

Question 8

whats the most obvious impact of scattering of waves?

Answer 8

Coda waves - the long string of little waves at the end of an EQ, all the scattered waves making their way through.