Seismic retrofit imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example. The retrofit techniques outlined here are also applicable for other natural hazards such as tropical cyclones, tornadoes, and severe winds from thunderstorms. Whilst current practice of seismic retrofitting is predominantly concerned with structural improvements to reduce the seismic hazard
Seismic inverse Q filtering from the phase. Comparing with fig.1.b. we can see that the smaller the reference frequency f in the forward solution,the more phase effect we get. In the inverse solution (1.8.a) we have the opposite effect,the higher value of f the more the forward phase effect is compensated, toward a causal solution. The graphs give a good illustration of Q-filtering according to the theory of Wang. However, more calculations should be done and more seismic models should be introduced. The effect of amplitude inverse Q-filtering should also be studied. Seismic inverse Q filtering Seismic inverse Q filtering is a data processing