<Li> passive control devices have no feedback capability between them, structural elements and the ground; </Li> <Li> active control devices incorporate real - time recording instrumentation on the ground integrated with earthquake input processing equipment and actuators within the structure; </Li> <Li> hybrid control devices have combined features of active and passive control systems . </Li> <P> When ground seismic waves reach up and start to penetrate a base of a building, their energy flow density, due to reflections, reduces dramatically: usually, up to 90% . However, the remaining portions of the incident waves during a major earthquake still bear a huge devastating potential . </P>

The best building material to use in an earthquake prone region is