The document discusses earthquakes, including their causes, measurement, effects, and zones of risk. Some key points: - Earthquakes are caused by movement of tectonic plates and faults in rocks. Their magnitude is measured on the Richter Scale and their intensity by the Mercalli scale. - Seismic waves transmit earthquake energy and are used to locate epicenters. The major earthquake zones are the Pacific Ring of Fire, Alpide Belt, and Mid-Atlantic Ridge. - India has five seismic zones of risk. Zone V including Kashmir and Northeast India faces the highest risk, while Zone I including parts of central India faces the lowest risk.