Geo-graphy notes for grade 12 on Earthquakes
Earth’s internal processes Earth Quakes Earth quake is defined as a violent tremor in the earth’s crust which sends out series of vibrating waves in all directions. Explanation of terms i. Origin: point at which begins. It is also called the focus. ii. Tremor: this is a vibration within the earth’s crust produced by gentle waves. When this vibration occurs on ocean floor, they produce tsunami (gigantic water wave up to 10m high). iii. Epicenter: the is the region immediately above the focus where the shock wave first hits the earth surface. iv. shock wave: there are two types: a. body wave: it travels through the earth crust and are two types: - Primary wave: it causes crustal rocks to move backward and forward in the direction of the wave movement. - Secondary wave causes crustal rocks to move from side to side at right angles in to the direction of the wave. b. Surface wave: this travel through
