Developments in the understanding about earthquakes associated with reservoirs have been reviewed, in particular based on Deterministic Chaos and Principal components analysis. Our analysis has shown that the earthquake system around Koyna reservoir is predictable with a minimum of 5 parameters in comparison to a large number of parameters around Nurek Dam in complex tectonic setting. Principal component analysis based on global data had brought out a better physical insight Into reservoir associated parameters about earthquake hazard assessment. The continued seismic activity around Koyna reservoir in relation to earthquakes of magnitude 5 could be analysed in greater depth than attempted so far using the same method.