The preparatory phase is phase in which a non-hydrostatic stress field is created in a certain region around a fault; direction of preparatory phase is to ultimately define size of actual earthquake. A number of ?foreshocks? are often recorded during this phase.

Structures built on loose soil or sediments or weak rocks will have to withstand greater risk compared to those founded on solid bed rocks in same region, or things being same.

In a storage dam, two types of forces have to be considered: Force due to dam and forces due to reservoir water.

Already exhaustive data has been collected to show that earthquakes occur along boundaries of plates moving apart each or.

Magnitude is term expressing rating of an earthquake on basis of amplitude of seismic waves recorded as seismograms.

The science dealing with study of earthquake in all ir aspects is called seismology. It is interdisciplinary science, which is partly geology and partly physics.

It is customary to mention earthquakes by its magnitude on Ritcher scale. Sometimes earthquakes are grouped into five classes on basis of magnitude.

Three classes of earthquakes are recognized on basis of depth of focus: shallow, intermediate and deep seated.

Foundations for concrete and masonry buildings should be excavated to same level throughout building, and should be, as far as possible of continuous type.

The post failure adjustment is phase during which medium is restored to a state of equilibrium involving series of ?after shocks? which are simply a manifestation of release of residual strain from rocks.