The science behind earthquakes what is an earthquake. It is then only intuitive that any additional stress acting on a fault system that approaches failure could trigger. The rocks then snap apart, releasing energy in the form of seismic waves figure 10. Life after death experience nde with steve gardipee, vietnam war story one of the best ndes duration. Ch 6 quiz multiple choice chapter 6 multiple choice 1. An earthquake is what happens when two blocks of the earth suddenly slip past one another.
A theory of tectonics in which the outer part of the earth lithosphere is comprised of rigid plates that interact collide, translate, rift apart, subduct. The elastic rebound theory is an explanation for how energy is spread during earthquakes. When the strength of the rock is exceeded, it suddenly breaks, releasing some of its stored energy as seismic waves. Reid, the elasticrebound theory of earthquakes, univ. How is the elastic rebound theory related to earthquakes.
However, based on studies in the tonga islands, earthquakes occur within the weak, ductile. When fault stresses rise above a critical threshold for rupture1, the earth slips along the fault and an earthquake results. On the morning of april 18, 1906, san francisco was struck by a violent earthquake that shook the city and ignited an even deadlier menace a threeday fire that burned up and down the citys streets and incinerated its buildings and neighborhoods. Due to the motion of the earths tectonic plates, the ground beneath our feet is always moving, just too slow and g. The elastic rebound theory for the origin of earthquakes was first proposed. The surface where they slip is called the fault or fault plane. Causes of earthquakes earthquake hazard and emergency management 27 c. Earthquakes that occur within plate boundaries, called intraplate earthquakes, have long intrigued. Jan 12, 2014 this snapping back into position, upon the release of strain, is the elastic rebound of reids theory the elastic rebound theory is an explanation for how energy is spread during earthquakes. Though it is releasing the energy equivalent of a 7. However, based on studies done in the tonga islands, earthquakes occur within the weak, ductile asthenosphere. Feb 22, 2014 1 the veolcity of s waves decreases as the waves enter the asthenosphere what does this suggest about the asthenosphere compared to the overlying lithosphere.
The elastic rebound theory is now well accepted as the reason for the occurrence of earthquakes. Types of earthquakes and faults most earthquakes in the world occur along the boundaries of the tectonic plates as described above and are called interplate earthquakes e. Slowly they deform, until their internal rigidity is exceeded. Earthquake precursors in the light of peroxy defects theory arxiv. The gradual accumulation and release of stress and strain is called the elastic rebound theory of earthquakes. Jan 24, 2012 a theory of small earthquakes teaches us something new about love and sex, jealousy and loyalty, and, most importantly, motherhood. The plane defined by the rupture is known as a fault, and the rock layers. How do earth scientists explain this contradiction. In 1906, henry fielding reid, professor of geology at johns hopkins university, concluded that the earthquake must have involved an elastic rebound of previously stored elastic stress.
This book presents an innovative new approach to studying source mechanisms of earthquakes, combining theory and observation in a unified methodology, with a key focus on the mechanics governing. However some of the characteristics of earthquakes can be explained by using a simple elastic rebound theory. This activity was developed for use in a high school grades 912 earth science class. Over time stresses in the earth build up often caused by the slow movements of tectonic plates. According to the elastic rebound hypothesis, most earthquakes are produced by the rapid release of energy stored in rock that has been subjected to great forces. According to the elastic rebound theory, rocks can bend elastically up to a point, until they finally break. This video discusses the relationship between plate boundaries and earthquakes, deformation, elastic limit and rebound and the 3 kinds of faults earthquakes can happen in. The elastic rebound theory of earthquakes bulletin of the department of geology, calif university of california.
Seismic waves free download as powerpoint presentation. The scale independent inclusion theory of rock failure developed in part i is applied to the problem of crustal earthquakes and, in particular, to the problem of premonitory phenomena reported to precede such earthquakes. In elastic rebound theory, what must occur to produce an. The location below the earths surface where the earthquake starts is called the hypocenter, and the.
The theory involves the slow build up of elastic strain due to largescale stresses in the crust on either side of a locked fault i. Reids elastic rebound theory usgs earthquake hazards. Rocks at the edges of tectonic plates are subject to tremendous forces resulting in intense deformation. The elasticrebound theory of earthquakes harry fielding. The elastic rebound theory of earthquake sources allows rough prediction of the occurrence of large shallow earthquakes.
Earthquakes earthquakes occur when energy stored in elastically strained rocks is suddenly released. Elastic rebound theory says that earthquakes are produced when a. Basically elastic rebound is the primary reason earthquakes even happen. The term refers to how the earth is built of plates, and the theory. Reids elastic rebound theory usgs earthquake hazard program. Dows recovery theory rocks recover violently when a mass collides with them. Illuminates the causes of earthquakes by elastic rebound theory and earthquake location as focus and epicenter. Elastic rebound theory is one of the central ideas to the mechanics of earthquakes and was originally proposed by reid 1910 following the 1906 san francisco earthquake on the san andreas fault. Earthquakes occur when a critical amount of stress is applied to the crust. In elastic rebound theory, what must occur to produce an earthquake. For example, they may be subjective assessments of damage following an event.
The model adopted in this paper assumes that a medium is permeated with a continuum field of defects and that a flow of defects describes an advanced. Ppt elastic rebound theory powerpoint presentation free to download id. New zealands geologic hazards agency reported this week an ongoing, silent earthquake that began in january is still going strong. If drainage is unable to occur, the tendency to decrease in volume results in an increase in pore pressure. The rise of earthquake science living on an active earth. The theory also predicted, of course, that the place would be along tectonic earthquakes. Several wellknown premonitory effects such as anomalous variation in the ratio of longitudinal v p and shear v s seismic velocities,v p v s, tilt, regional and local. Learning earthquake tip 1 earthquake design and construction. According to the elastic rebound theory reids, 2 the seismic cycle consists of two.
Duponts plasticslip theory rocks store bending energy until they cannot store it any longer, then snap like a rubber ball. Ayelet waldman, author of bad mother and red hook road in her ten previous nonfiction books, meredith maran has trained her journalistic eye on the subtle dance between the political and the personal. The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific. Transfer due to slip on the fault, and is defined as. As the earths crust deforms, the rocks which span the opposing sides of a fault are subjected to shear stress. D chandrasekharam department of earth sciences head, centre of studies in resources engineering indian institute of technology bombay such news items raises several questions like what are earthquakes. The goal of this lesson is for students to learn the concepts of elastic rebound and friction and how these apply to earthquakes and faults. At some point the stresses become so great that the. In geology, the elastic rebound theory is an explanation for how energy is released during an earthquake. Reid gave, for example, a crude forecast of the next great earthquake near san francisco. As rocks on oppo site sides of a fault are subjected to force and shift. Pdf physical mechanism of major earthquakes by earthquake cases. Obviously, the fault deformation in the elastic rebound hypothesis is.
Ppt elastic rebound theory powerpoint presentation. Elastic reboundtheory elasticrebound theelasticreboundtheoryisanexplanationforhow energyisspreadduringearthquakes. Instructional material complementing fema 451, design examples earthquake mechanics 2 21 if a saturated sand is subjected to ground vibrations, it tends to compact and decrease in volume. Previously it was thought that ruptures of the surface were the result of strong ground shaking. Pdf understanding the physical mechanism of major earthquakes is very important for earthquake prediction. In geology, the elastic rebound theory was the first theory to satisfactorily explain earthquakes. Reids elastic rebound theory not only allowed to explain the. According to the elastic rebound hypothesis most earthquakes. Elastic rebound earthquake mechanism slippage at the weakest point the focus occurs. A number of earthquakes also occur within the plate itself but away from the plate boundaries e. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext.
Earthquakes mechanics and effects civil engineering. Mar 09, 2016 this video discusses the relationship between plate boundaries and earthquakes, deformation, elastic limit and rebound and the 3 kinds of faults earthquakes can happen in. Reids elastic rebound theory rocks store elastic energy until they cannot store it any longer, then snap like a rubberband. In geology, the elasticrebound theory is an explanation for how energy is released during an earthquake. This release of energy causes intense ground shaking in the area near the source of the earthquake and sends waves of elastic energy, called seismic waves, throughout the earth. Triggering of aftershocks of the japan 2011 earthquake by. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Elasticreboundtheory elasticrebound theelasticreboundtheoryisanexplanationforhow energyisspreadduringearthquakes. Sometimes seismological data are not based directly on seismograms. In the past, earthquakes were believed to occur because the ground would shake in a very strong manner. From an examination of the displacement of the ground surface which accompanied the 1906 earthquake, henry fielding reid, professor of geology at johns hopkins university, concluded that the earthquake must have involved an elastic rebound of previously stored elastic stress. What was learned scientifically from 1906 1906 marked the dawn of the scientific revolution reids elastic rebound theory soil types and damage big quakes can be followed by decades of inactivity paleoseismology 1906 earthquake photos eyewitness accounts other major earthquakes in the sf bay area learn more about earthquakes acknowledgements. Elastic rebound theory moment magnitude scale earthquakes.
Elastic rebound theory is directly related to earthquakes. Earthquakes most often occur along existing faults whenever the frictional forces on the fault surfaces are overcome. New explanation for slow earthquakes on san andreas. The mechanisms and processes involved when earthquakes occur are extremely complex. After the devastating 1906 san francisco, california earthquake, a fault trace was discovered that could be followed along the ground in a more or less straight line for 270 miles. In the standard rebound theory of earthquakes, elastic deformation energy is. Nov 17, 20 the elastic rebound theory predicts that earthquakes can be generated only in the lithosphere. View notes ch 6 quiz multiple choice from esc at florida state college at jacksonville. Vibrations earthquakes occur as the deformed rock springs back to its original shape elastic rebound. According to the elastic rebound theory reids, 2 the seismic cycle consists of two phases. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates.
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