Earthquake is the tremor in earth's crust caused either by volcanic eruptions or by sudden dislocation in the rock structure underneath. The usual phenomena of an earthquake are at first the feeling of a tremor, next two or three severe shocks on earth, and then again there may be a tremor for a short period of time. Sometimes, mild quivering of the earth may continue for several days. An earthquake causes unaccountable damage, and sometimes heavy destruction of life and property. If the tremor is strong, the houses rock violently, sometimes causing the high buildings come down, burying the inmates. An earthquake causes the trees move unusually as in a storm, and the tanks and the rivers thrown into unusual commotion. During an earthquake, it is unsafe to remain inside a multi-storied house. Houses made of thatch and bamboo is more of less safe. The ground floors of buildings are also comparatively safe. It is better for the inmates of houses to come out in the open at the time of an earthquake. Generally, the neighbours are alerted fearing an earthquake by blowing" conch-shells. Even at the dead of the night in a village, the sound of conch-shells may awake and alert the sleeping people about an earthquake. The earthquake of 1934 that took place in Bihar and in a part of Nepal was very strong, destructing thousands of human lives and cattle. In Japan, an earthquake is a common phenomenon. It takes place frequently than in other countries in the world. In India, earthquake is, however, felt from time to time in mild form in different parts of the country.