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Describe the direct and indirect sources for the internal study of the earth

Answer» There are two sources for information about interior of the earth – a) Direct Sources and b) Indirect Sources:•Direct Sources: Mining, drilling and volcanic eruption are examples of direct sources. During the process of mining and drilling rocks and minerals are extracted which gives information that there are layer system in the crust. Crust is made of many kinds of rocks and minerals. Volcanic eruption suggests that there is some zone inside the earth which is very hot and in liquid condition. Direct sources are not very reliable because mining and drilling can be done only up to some depth only.Indirect Sources: Seismic waves, gravitational field, magnetic field, falling meteors etc are example of indirect sources. They are very important for know about earth‘s interior. Movement of seismic wave suggests that there are three layers in the earth and each layer has different density. Density increases toward the center of the earth.<br>The\xa0direct sources\xa0are those that provide first-hand information about events whereas the indirect sources\xa0involve the reports and analysis of\xa0direct\xa0information by other people.\xa0In scientific disciplines, experiments are the most common\xa0direct source; in other disciplines, surveys and interviews, or research into written and oral records of events provide\xa0direct\xa0access to information.\xa0Most of our\xa0information\xa0about\xa0earth\'s interior\xa0has come from seismic studies. Seismic waves produced during an earthquake are recorded by a seismograph when these waves reach the surface of the\xa0earth. There are two types of seismic waves- body waves and surface waves.


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