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Historical Note on Earthquakes
Published in Santiago Pujol, Ayhan Irfanoglu, Aishwarya Puranam, Drift-Driven Design of Buildings, 2022
Santiago Pujol, Ayhan Irfanoglu, Aishwarya Puranam
The shell of the earth, the crust, can be said to have two different thicknesses. Under the oceans, it is relatively thin. It varies in thickness from 5 to 8 km. Under the land masses, it is relatively thick. The thickness of the continental crust varies from 10 to 65 km. The eggshell analogy for the crust is not an exaggeration. It is paper thin compared with the radius of the earth, which is approximately 6,400 km. The total weight of the continental crust is less than 0.3% of the weight of the earth. Variations in the crust thickness are compensated by the weight of the water and the differences in the specific gravities of the crust under the oceans (3.0–3.1) and under the continents (2.7–2.8). If one thinks of the crust as virtually floating on the mantle, one is less likely to wonder why the earth does not wobble as it rotates about its axis. The weight of the crust plus the mantle has a reasonably uniform distribution over the globe.
Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
The earth’s crust is a thin layer of igneous, metamorphic and sedimentary rock covering the earth’s surface (already discussed). The earth’s crust can be divided into the continental (land) crust and the ocean crust. The oceanic crust consists of the sea bottom. Both crusts exhibit similarities as well as clear distinctions. The continental crust is lighter, lower-density and thicker than the ocean crust. The thickness of the continental crust varies from 20 to 70 km, whereas the thickness of the ocean crust is almost uniform and constant (8–10 km). The continental crust is made up of lighter minerals containing lighter elements such as silicon, aluminum and calcium; the ocean crust is predominantly made up of the heavier minerals containing heavier elements magnesium, iron and nickel. The ocean bottom crust is more active geologically. Underground geological phenomena are more pronounced in the ocean bottom than on land. Both types of crust are constantly being made and broken. However the continental crust is comparatively stable.
Environmental Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Another important feature of our planet is its geological activity such as volcanic fissures and lava eruption. The earth’s crust (or continental crust) is the outermost solid land surface of the earth. It is chemically and mechanically different from the underlying mantle and has been generated largely by igneous processes in which magma (molten rock) cools and solidifies to form solid land. Plate tectonics, mountain ranges, volcanoes, and earthquakes are geological phenomena that can be explained in terms of energy transformations in the earth’s crust and might be thought of as the process by which the earth resurfaces itself. Beneath the earth’s crust lies the mantle, which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of magma, which is in a state of semi-perpetual convection. This convection process causes the lithospheric plates to move, although slowly. The resulting process is known as plate tectonics. Volcanoes result primarily from the melting of subducted crust material. Crust material that is forced into the asthenosphere melts, and some portion of the melted material becomes light enough to rise to the surface, giving birth to volcanoes.
On torsional wave in void type porous layers between viscoelastic and piezoelectric media with parabolic irregularity
Published in Waves in Random and Complex Media, 2023
Pato Kumari, Rupali Srivastava
For the present problem, a void-type porous layer has been considered, which is overburdened by an initially stressed inhomogeneous viscoelastic layer. The layer is placed over a piezoelectric substratum. Earth’s crust contains elements such as Granite (also known as the planet's signature rock), which is a kind of piezoelectric material. The continental crust also has typical chemical constituents that are broadly granitic. Piezoelectric materials are also used in various geophysical applications, such as seismic sensing, acoustic wave sensing, and ultrasonic testing, which can provide information on the porosity, permeability, and fluid content of the reservoir. Similarly, piezoelectric sensors have been used to measure the seismic properties of rocks, which can help identify subsurface structures such as faults and fractures, thereby motivating the authors to incorporate piezoelectric media as a substratum to the porous layer in the proposed geophysical model for the present research.