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Role of Emerging Technologies in Energy Transformation and Development of Clean and Green Energy Solutions
Published in Anirbid Sircar, Gautami Tripathi, Namrata Bist, Kashish Ara Shakil, Mithileysh Sathiyanarayanan, Emerging Technologies for Sustainable and Smart Energy, 2022
Geothermal energy is derived from internal heat of earth. This energy is present in the fluid present in the pore spaces of rocks due to some anomalous heat source present in earth’s crust. Geothermal energy sources have been broadly divided into low enthalpy and high enthalpy reservoirs (Kazmarczyk et al. 2020). Several workers have done detail investigation of geothermal provinces in India (Craig et al., 2013; Dimri 2013; Yadav and Sircar, 2021) and other parts of world (Gunnlaugsson, 2004, Carella, 1985). The hot water and steam gush out to surface due to their subsurface heating. One of the most common heat sources is subsurface magma chamber, which is a reservoir of molten rocks at high temperatures. Radioactive isotope decay and resultant energy generation in the earth’s crust is also another important source of geothermal energy. Mantle convection results in transfer of heat from lower mantle to lithosphere, which is also a source of geothermal energy.
Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
In 1929, shortly after Wegener proposed that continental drift occurred, Arthur Holmes suggested that convection, involving flow of generally solid material, occurs in the mantle. He proposed that hot materials are less dense than cold materials are and will naturally rise to Earth’s surface where they will split the crust. Continued upward flow forces the crust to move apart and, when they cool, pieces of the crust will eventually descend back to depth again. According to Holmes, these two processes could drive the continental drift proposed by Wegener. It was not until the 1960s, however, that Holmes’s ideas received much attention. Today, mantle convection is acknowledged as a key driver of plate tectonics. Although the mantle is mostly solid, because it is hot and somewhat elastic, it can flow like an extremely viscous liquid. Flow rates are slow, but over geological time, the distances can be great.
Earthquake prediction
Published in Ömer Aydan, Earthquake Science and Engineering, 2023
The plate tectonics theory has been presumed to be able to answer the causes of tectonic stresses and to explain why earthquakes occur along some regions. However, this theory is also insufficient to explain intra-plate earthquakes as the theory is based on rigid body kinematics. The driving force for plate tectonics is assumed to be mantle convection, which is thought to be resulting from nonuniform temperature distribution in the upper mantle caused by subducting plates. There is no doubt that such a temperature difference could cause the convection. Then, the questions are why subduction of plates occurs and why Earth’s surface is divided into several plates. There are probably no answers to these questions in the field of geophysics, presently. As explained in Chapter 2, Aydan (1995a) analysed the stress state of Earth by modelling it as a spherical object consisting of layers exhibiting thermo-elasto-plastic behaviour under pure gravitational acceleration. He was able to show that the whole of Earth could not be an elastic object at all and it must have already been in a plastic state. This simply implied that the fracturing and plastic yielding of the whole mantle must have taken place in its geological past together with tangential and radial stresses being the compressive maximum and minimum principal stresses, respectively. This finding also indicated that subduction or overriding phenomenon should occur within Earth’s crust, and the mantle so that the conditions for mantle convection may be generated. It should not be forgotten that Earth is a part of the solar system. Earth rotates around the Sun with a varying speed between 29.3 and 30.321 km/s, and it wobbles. These facts should certainly cause some special circumstances to disturb its spherical symmetry, resulting in material inhomogeneity. Within this perspective, we have to consider the rupturing of Earth’s crust, resulting in earthquakes.
An XFEM Model for Seismic Activity in Indian Plate
Published in Journal of Earthquake Engineering, 2018
S. Jayalakshmi, S. T. G. Raghukanth, B. N. Rao
However, there are numerous drawbacks existing in the present methodology. One of the important challenges in seismic hazard analysis is to estimate ground motions for large return periods that range between 10,000 and 1 million years. The earthquake catalog will not be complete for this duration. Tectonic processes including plate movements, mantle convection, and the formation of faults also play an important role in estimating seismic hazard. Therefore, mechanistic models based on long-term behavior of the plate are likely to provide insights on seismic activity for this period and parameters such as upper bound magnitude (mu) can be established from such models. Another difficulty in the present modeling approach is that the model cannot represent seismic activity along the depth profile of a particular fault. The fixed boundary condition along Himalaya absorbs deformations and yields maximum stresses in this region. Lastly, the approach used in the modeling cannot be used to simulate site-specific ground motions due to earthquakes since it requires definition of material properties in higher resolution. The implementation of material properties from velocity and density variations in the crust is difficult due to the lack of availability of data. Hence in the present study, the range of values from the properties of rock are chosen between 1–100 GPa for Young’s Modulus and 0.25–0.4 for Poisson’s ratio [Turcotte and Schubert, 2002] for the various regions of the plate. This limitation can be overcome with the availability for more data on crustal velocity structure for a large part of Indian Plate. Thus, the scope of the present study is limited to computation of the weightage factors for faults in India and their activity parameter ‘C’ in Eq. (16). Further availability of data, including GPS measurements and velocity models, is likely to improve and update the mechanistic model for estimation of more parameters related to seismic hazard.