An earthquake is the shaking of the Earth's surface caused by a sudden release of energy in the lithosphere that causes seismic waves. Key Point An earthquake is a sudden release of energy in the earth's crust that causes the earth's surface to shake. The number, nature, and size of earthquakes experienced in a given area are referred to as seismicity or seismic activity. The type and severity of an earthquake are determined by the seismic activity in the area. precautionary measures should be taken to avoid and reduce the devastating effects of seismic events are following: All buildings in high-risk areas should include earthquake-resistant elements.​ To curb deforestation and large scale quarrying in mountain areas so that landslides, avalanches can be reduced. Construct earthquake-resistant communal facilities and buildings such as schools, dharamshalas, hospitals, prayer halls, and other structures, particularly in seismic zones with moderate to higher intensities. Restricting urban development in hilly areas. Mechanisms for obtaining precautionary funds or sharing risks in order to give relief, rehabilitation, and reconstruction. Supporting research and development in the areas of disaster mitigation, preparedness, and prevention, as well as post-disaster management. Thus, Statements I and II are correct. Additional Information The Richter magnitude scale was the first of the instrumental scales used to describe the size of an earthquake, which was developed in the 1930s. Different types of seismic waves Longitudinal P-waves (shock- or pressure waves) Transverse S-waves (both body waves) Surface waves – (Rayleigh and Love waves) Some events of earthquake in India are the Cutch Earthquake (1819), the Assam Earthquake (1897), Bihar-Nepal Earthquake (1934), Koyna Earthquake (1967), Uttarkashi (1991), Killari (1993), Bhuj (2001), Jammu Kashmir (2005)