A seismic wave is a wave that travels through the Earth, most often as the result of a tectonic earthquake, sometimes from an explosion. Seismic waves are also continually excited by the pounding of ocean waves and the wind. Seismic waves are studied by seismologists, and measured by a seismograph, which records the output of a seismometer, or geophone.

focus= To center the vision upon. To set so as to form a perfectly clear image, as the lenses of eyeglasses, a telescope or a camera. seismic waves=Wave caused by an earth quake. frequency= The number of repeated operations of a mechanical part in a unit of time as in vibration or revolution. The number of cycles persecond produced by the generator of an alternating electric current. Mercalli scale=measure the affect of the earthquake at different sites. epicentre= Area on the earth’s surface directly above the point of origin of an earthquake. magnitude=is the size, greatness of bulk or extent. the importance. Richter Scale= assigns a single number to quantify the size of an earthquake.