ground motion prediction equations

Question 1

why are they usually prediction instead of numerical simulation?

Answer 1

simulation is extremely complex and cumputationally expensive. requires a lot of expertise to do correctly

Question 2

what are some common variables used for GMPEs?

Answer 2

intensity/magnitude, distance (using varying metrics for this), site terms (like vs30), faulting style, fault orientation and geometry, focal depth,

Question 3

whats a way to break down GMPEs into comoonents?

Answer 3

GMPE = source term + path term + site term

Question 4

write out a simple example of a gmpe

Answer 4

logY = a1 + a2M + a3M^2 - a4log(D) + Cs + Cr + sigma
first three are to do with magnitude, another to do with distance / attenuation, another for site and region adjustments, and SIGMA dont forget uncertainty

Question 5

name different measures of distance to a source

Answer 5

epicentral - surface distance
hypocentral - to focal point
joyner-boore - distance to the vertical projection on the surface of the rupture
sesismogenic distance - distance to the seismogenic part of the rupture

Question 6

what is the hanging wall effect?

Answer 6

that sites above the fault on the hanging wall will have larger PGA than sites at the same distance on the footwall as they are closer to a larger area of the fault