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Petroleum Seismological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Seismology is the study of earthquakes. Seismic waves are naturally generated during earthquakes and accompanied by movement or vibration of the earth’s crust. The crust vibration is due to the traveling wave energy through the underground structure. Petroleum seismology is the study of the geological characteristics of underground sedimentary rock, through artificially created seismic waves. The seismic wave or energy produced at the surface travels into the ground and results in a variety of reflected, refracted, head refracted and transmitted waves. The reflected and head refracted waves appear back at the surface, whereas the refracted and transmitted waves travel deep into the ground and are lost. The study of reflected and head refracted waves lead to information on the path traveled through the subsurface rock strata in terms of change in the characteristics of the seismic wave. The nature of the strata affects the traveling seismic wave. Change in the characteristics of wave is related to the subsurface rock structure. Petroleum seismology for oil/gas prospecting gives more certain and reliable information than the other geophysical survey methods. The survey is close to the geological reality of the subsurface structure. Besides petroleum prospecting, other areas where seismology is employed are ground engineering, environmental, coal, minerals, hydrology and geothermal studies. The study ranges from shallow to deep earth crust.
Frames
Published in Rob Whitehead, Structures by Design, 2019
Engineers and product manufacturers use physical models for seismic testing more commonly than architects. Very large modeling, including full-scale buildings, can be placed upon a giant moving plane that simulates seismic movement—a larger and more accurate version of a shake-table. These tests help us understand how materials, connections, or energy-absorbing elements perform under seismic loads. We may use information gathered from these tests to create digital simulations. Advancements in dynamic digital modeling have enabled structural designers to better understand the effects of different magnitude earthquakes on buildings. Despite this information, seismic events still have devastating effects, particularly when buildings are constructed of heavy, non-reinforced masonry or concrete—typically a consequence of economic hardship and lack of access to more ductile structural material. The magnitude of seismic forces is measured in the Richter scale; a logarithmic scale system in which each whole number represents a ten-fold increase in amplitude, or nearly 32 times the amount of energy released, from the whole number below. Because a potential earthquake’s magnitude is never known, we design buildings to resist a range of potential forces. But sometimes earthquakes exceed what codes anticipate.
Sensors and sensory systems
Published in You-Lin Xu, Jia He, Smart Civil Structures, 2017
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, nuclear explosions and other sources. As ground motion causes its frame to move, a fixed reference point is required for a seismometer taking measurements. Hence, the installation of a mechanical oscillator can be in the form of a mass-spring system (mobile mass attached to the frame by a spring) or a horizontal pendulum (mobile mass offset from the vertical axis of rotation). Accordingly, there is one way to classify the seismic sensors based on the measurement direction and the aforementioned properties of a mechanical oscillator: either vertical or horizontal. A vertical seismometer, which is used to measure vertical ground motion, utilises an oscillator based on the mass-spring system to compensate for gravity. A horizontal seismometer, which is used to measure horizontal ground motion, is based on the horizontal pendulum principle.
Assessment of Multi-Criteria Evaluation Procedures for Identification of Optimal Seismic Retrofitting Strategies for Existing RC Buildings
Published in Journal of Earthquake Engineering, 2022
Wilson Wladimir Carofilis Gallo, Giammaria Gabbianelli, Ricardo Monteiro
Seismic retrofitting foresees the upgrade of existing buildings, by addressing the aspects that render them vulnerable and compromise a proper performance and the safety of their occupants during earthquake events. Many retrofitting solutions have been studied and adopted in various building types for the past decades, from conventional approaches to more sophisticated methods, as discussed in the work by Pampanin (2006). A vast range of different options, techniques and materials are available to significantly improve the overall performance of existing buildings. For instance, Fig. 1 outlines a series of strategies suggested by ATC-40 (1996), which addresses structural strengthening and stiffening as well as the increase of a building’s deformation capacity. Additionally, ATC-40 (1996) discusses base-isolation and energy dissipation devices as alternatives to act upon the seismic demand side, decreasing it.
Framework for calculating seismic fragility function of urban road networks: A case study on Tangshan City, China
Published in Structure and Infrastructure Engineering, 2021
Ding Wang, Xiaowen Wang, Jun Xu, De-Cheng Feng, Shan Xu
It is generally known that the seismic motions on the ground surface are due to the earthquake waves which are generated by the source and spread in the rock or soil layers. The wave passage effect, the extended source effect, the scattering effect and the attenuation effect all cause the spatial variation of the seismic ground motions (Zerva, 2009). For long-span structures and lifeline systems, the spatial variation of seismic ground motions may significantly affect their responses and damage patterns. The urban road network is one of the lifeline systems which extended spans are so large that the spatial variation of seismic ground motions must be considered. In this article, the edges are subjected to different seismic ground motions during the earthquake because of the spatial variation of seismic ground motions. The ground motions at the midpoints of the roads are generated and used for the fragility evaluation of the single road sections.
Impact of curved boundary on the propagation characteristics of Rayleigh-type wave and SH-wave in a prestressed monoclinic media
Published in Mechanics of Advanced Materials and Structures, 2021
Shalini Saha, Abhishek Kumar Singh, Amares Chattopadhyay
Seismic waves are mechanical disturbance or energy packet propagating through the Earth’s interior generated due to earthquakes, volcanic eruptions, movement of magma, chemical explosion. Mostly two types of seismic waves viz. Body waves and Surface waves contribute to the shaking and trembling of Earth’s surface. Body waves are comprised of two different waves namely P-waves and S-waves and are propagating through the volume of Earth’s interior. The surface waves travel near the surface of the Earth. Among several type of surface waves, Love wave and Rayleigh wave are the two which are responsible for major destruction on the Earth’s surface. The studies of propagation behavior of seismic waves in different material medium unravel many facts regarding Earth’s interior structure as these waves grasp a great deal of information about the seismic source and physical properties of the medium through which they propagate. Moreover, the analysis of the seismic waves further aids in investigating the mechanisms, locations, and magnitude of earthquakes and in designing a more relevant model of Earth’s interior. Although it is a complicated task to exactly model the seismic wave propagation through the Earth’s interior, several authors, assuming various approximations and assumptions in their theoretical model, have made attempt to demonstrate the excitation of seismic waves and their relation to the physical properties of the Earth.