- Ground-motion model is:
where PGA is in g, C1 = -7.515, C2 = 1.049, C3 = -0.105, C4 = -0.0211, C5 = -0.287 and σ = 0.511.
v = 0 for horizontal PGA and 1 for vertical PGA.
- Data from basalt sites (7 stations), thick hard lateritic soil underlain by basalt (1 station) and dam galleries
- Data from 13-station strong-motion network (AR-240 and RFT-250 instrument types) close to Koyna
Dam. Exclude data from dam top. Use data from foundation gallery because believe they can be considered
as ground acceleration data. Select set of 31 significant records after scrutinizing all data.
- Correct for instrument response and filter using cut-off frequencies based on a signal-to-noise ratio > 1.
- Use a 2-stage regression method. Firstly, find C1, C2 and C5 (magnitude and component dependencies)
and then find updated C1, C3 and C4 (distance dependence) using residuals from first stage.
- Find that equation matches the observed data quite well.