Miscellaneous Study Materials 15 Nov 2019

Seismic Activities (Geography)

Seismic Activities Earthquakes

In Earthquake, there is a sudden release of energy in the Earth’s crust, which leads to a series of motions because of the waves created due to this energy released. The waves are called Seismic Waves. We have studied the types of seismic waves already. These seismic waves originate in a limited region and spread in all directions. We have also studied that all that we know about what happens in the mantle and cores of the Earth has been derived from circumstantial evidence-mostly the analysis of seismic data. Scientists use earthquake waves to better understand the Earth’s interior. As speculated by the scientists, the first earthquake probably occurred sometime after the Earth’s crust had cooled enough to become solid some 4.55 billion years ago. Ancient records of earthquakes are scarce, despite the fact that writing had started as back as 8000BC. Earliest record of Earthquakes is from China dating back to 1177 BC.

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Volcanoes & Volcanism

A volcano is simply an opening in the Earth‟s surface in which eruptions of dust, gas, and magma occur; they form on land and on the ocean floor. The driving force behind eruptions is pressure from deep beneath the Earth‟s surface as hot, molten rock up wells from the mantle The results of this activity are a number of geological features, including the build-up of debris that forms a mound or cone, which we commonly imagine when talking about a volcano.
An opening or vent through which the magma, molten rocks, ashes, gases and other volatiles erupt on the surface of Earth is called a Volcano. The most known types of Volcanoes are conical mountains which spit law and poisonous gases. But there are other types of Volcanoes. Download Attachment