GEOGRAPHY AND HISTORY

  Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs . There are two main types namely:   1. Body waves   2. Surface waves.        BODY WAVES . These are waves that travel through the surface of the earth. (a) Primary waves.   They cause each crustal rock to move back and forth along the direction of the Wave movement. They are also the fastest waves.   (b) Secondary waves. Referred to as shake or shear waves since they cause the crustal rock particles to vibrate vertically to the direction of the waves movement.    Surface waves. They travel on the surface of the earth and are responsible from a third set of impulses.Surface waves are divided into love waves and LRayleigh waves Love Waves The first kind of surface wave is called a Love wave, named after A.E.H. Love, a Br...

  Approach Define vulcanicity Explain the origin/ causes Identify forms of drainage Identify land forms resulting from vulcanicity associated with drainage with specific examples from East Africa. Answer Guide Volcanicity is the process through which gases and molten rocks are extruded onto the earth’s surface through a central vent or fissures. Volcanicity is brought about by radio activity and geo-chemical reactions in the interior generating intense/ great heat and pressure; melting mantle rock into molten rock/ magma. Some times molten magma forms as a result of Friction between moving rocks during plate movement and faulting. High pressure pushes out the magma into the crust; rising towards the surface through vent and lines of weakness such as faults created by tectonic forces/ movements such as faulting. The shape and the size of the volcanic landforms are determined by the chemical composition/viscosity of magma and the nature of volcanic eruption. That is acidic (high sili...