Propagation of a Plane Wave
Plane Wave Approximation from a Spherical Front
Displacements for P and S waves
Radial and Transverse Motion of P and S Waves
Radial and
Transverse Energy
N-S and EW
components have nearly
equal amplitude and
energy (BAZ is 323o)
Rotate the seismogram
to produce Radial and
Transverse components
SKS and SKKS are P to
Sv converted phases and
are strongest on Radial
Sdiff has mostly Sh
energy and is strongest
on Transverse
Particle Motion
If we plot the particle motion for the Radial versus the Transverse component
The SKS phase shows the most energy on the Radial
The Sdiff phase shows the most energy on the Transverse
S wave delays
Note the S wave arrival times on the N-S and the E-W components.
Are they coincident ?
Why or Why not ?
If you see a time delay or offset, what is causing this ?
Seismic and Mineral Anisotropy
P and S wave differences
Effects of Ground Composition on Seismic Energy
Seismometer ground displacements from 1989 Loma Prieta earthquake
Magnitude 5 aftershock
Seismometer on solid bedrock (above)
Seismometer on filled land (below)