Molten areas within the earth slow down p waves and stop s waves because their shearing. Graph of earthquake compressional wave velocity and density in. Identifying and understanding earthquakes using seismic. Seismic waves are waves of energy that travel through the earths layers and are a result of earthquakes, volcanic eruptions, massive landslides and large humanmade explosions. Seismology and earth s interior there are two categories of earthquake waves. The periods of the earths free oscillations depend on the elastic moduli and densities of the interior. An earthquake radiates p and s waves in all directions and the interaction of the p and s waves with earths surface and shallow structure produces surface waves. Body waves traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. Just as the prism below refracts light at its faces, seismic waves bend, reflect and change speed at the boundaries between different materials below the earths surface2. Overall, this type of seismic wave is the most destructive.
Seismic waves and earths interior penn state earthquake. Importance of understanding the interior of the earth understanding the structure of the earths interior crust, mantle, core and various forces heat, seismic waves emanating from it is essential to understand the evolution of the earths surface, its current shape and its future. Seismic waves and earths interior measuring and locating earthquakes. A seismologist is a scientist who studies earthquakes and seismic waves. Feb 26, 2017 description of the properties of p primary and s secondary waves. Seismic waves travel more quickly through denser materials and therefore generally travel more quickly with depth. 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. Description of the properties of p primary and s secondary waves.
Describe the characteristics of seismic waves and explain the difference between primary waves, secondary waves, and surface waves. Students complete fill in the blanks and draw a diagram of the interior of the earth. S waves, known as secondary waves, are seismic waves that simply go about in an s shape, form, and is the second wave to arrive during an earthquake. Evidence on the structure and composition of the earths interior comes from 1 observations of surface rocks, 2 geophysical data from earthquakes, flow of heat from the. Pdf this chapter outlines some of the understanding of the earths interior derived from. Es15 seismic waves teacher prep science from scientists.
The division of the earth into the earths crust, mantle and core, the later division into socalled bullen zones, or the latest laterally. The scientific study of the earths interior structure is enabled by the utilization of two types of energy waves. Youve seen my video on the actual layers of the earth, and seismic waves are crucial to actually realizing how people figured out what the different layers of the earth are. The refraction or reflection of seismic waves is used for research into the structure of the earths interior. Seismic waves oscillations propagating in the earth from the foci of earthquakes, explosions, and other sources. Near the foci of strong earthquakes, seismic waves have destructive force over a period of tenths of a second. Seismic waves article about seismic waves by the free. Earths interior seismic evidence explanation duration. From seismic tomography, first introduced in the late 1970s refs 1, 2, we now have a good understanding of the firstorder characteristics of the longwavelength 1,0002,000 km threedimensional elastic structure of earths. This product includes cornell notes, an activity, a presentation on the lesson, and a mini quiz built into the presentation on how seismic waves pass through earths interior. Pdf earth is a very unique planet in the solar system.
The most important information on the constitution of the earths interior has been obtained from studies of seismic body waves longitudinal and transverse seismic waves propagating through the earth. Seismic waves that travel through earth s interior primary p, waves a type of seismic wave that involves alternating compression and expansion push together and pull apart of the material through which it passes. When seismic waves pass between geologic layers with contrasting seismic. For ocean waves sometimes called seismic sea waves, see tsunami.
A the focus of the earthquake is directly below the epicenter. Observations of the propagation of seismic waves made on the earths surface make it possible to study the structure of the earth. By studying the seismic waves, scientists discovered several different layers. This lesson includes the following main ideasvocabulary. Seismic waves can be defined as, the waves of energy caused by the sudden breaking of rock within the earth or an explosion1. Primary waves p waves for short travel the fastest and are the first or primary. Earths hum helps probe planets interior earths layers. The lithosphere is free to move glide over the weak asthenosphere.
The ambient seismic noise that makes earth hum could help scientists map the planets interior, from the crust, through the mantle and possibly to the core. This product is part of my earthquake interactive notebook bundle. A free powerpoint ppt presentation displayed as a flash slide show on id. Geological survey 1200 south eads street, arlington, va 22202. How do seismic waves help us visualize earths layers. Surface waves can only travel very near the surface of the earth. Seismic waves that travel through earths interior primary p, waves a type of seismic wave that involves alternating compression and expansion push together and pull apart of the material through which it passes. Unit 2 quiz earths interior swaves, a type of seismic wave, cannot travel through liquids.
Nov 26, 2012 the ambient seismic noise that makes earth hum could help scientists map the planet s interior, from the crust, through the mantle and possibly to the core. This quiz and worksheet combination will help you test your understanding of how. Vibration of earth produced by the rapid release of energy 2. The large earthquake that triggered the tsunami of 2004 sent waves of energy through much of the planet. Seismic waves generated in earths interior provide images that help us to better understand the pattern of mantle convection that drives plate. Many earthquakes happen because of stress on local areas of rock.
Earths interior 1 earths interior 2 no transcript 3 discovery of earths layers. Among the many types of seismic waves, one can make a broad distinction between body waves, which travel through the earth, and surface waves, which travel at the earths surface 4850. List the key observations that revealed earth to possess a. Students test several models of the interior of the earth beginning with a simple homogeneous earth and moving toward more complex multilayered earth models. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. The refraction or reflection of seismic waves is used for research into the structure. A model is a simplified mathematical representation of the actual threedimensional material property variations within the. Seismic tomography of the earths interior article pdf available in american scientist 725 september 1984 with 342 reads how we measure reads. The earths interior structure lecture 1 how do we know whats inside the earth. This article is about waves that travel through the earth.
Seismic wavefield imaging of earths interior across. Gravitation and the diameter of the earth help in estimating pressure deep inside. This fact sheet uses data from the 1994 magnitude 6. Explain the elastic rebound theory, which provides an explanation for the origin of earthquakes. This product includes cornell notes, an activity, a presentation on the lesson, and a mini quiz built into the presentation on how seismic waves pass through earth s interior. This worksheet has 3 multiple choice, 3 matching, 12 fill in the blank, and 6 short answer questions. Ppt types of seismic waves powerpoint presentation free. Earthquakes and the earths interior earthquakes earthquakes occur when energy stored in elastically strained rocks is suddenly released. Seismic velocities depend on the material properties such as composition, mineral phase and packing structure, temperature, and pressure of the media through which seismic waves pass. The ambition to constrain the structure of earths interior using complete seismicwave propagation physics dates back to the early 1980s fig. How the study of seismic waves help us to understand the. Waves of energy that travel through the earth s layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large manmade explosions. Seismic waves and earth s interior see page 2 this document for an i incoming ray angle measured from vertical extract from chuck ammons excellent v1 velocity of that ray. Using seismic waves to image earths internal structure.
Seismic surface waves in laterally inhomogeneous earth. Modeling the interior of the earth using seismic waves. 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. While some of the waves occur on the surface, other waves of energy move through the planet at very deep levels.
There are two kinds of body waves, and two kinds of surface waves. Earthquakes occur when energy stored in elastically strained rocks is suddenly released. Earthquakes create seismic waves that travel through the earth. Interior of the earth lab microsoft word 121kb feb9 06 is a word file that is what the students use and fill out. Seismic waves are used to determine the depth of layers of molten and semi molten material under the top surface. This is an inquirybased student exercise designed to explore how we use seismic waves to understand the structure of the earth s interior.
Earthquakes and the earth s interior earthquakes earthquakes occur when energy stored in elastically strained rocks is suddenly released. Robertson abstract evidence on the structure and composition of the earths interior comes from 1 observations of surface rocks, 2 geophysical data from earthquakes, flow of heat from the interior, the magnetic field, and gravity, 3 laboratory ex. Earths interior earthquake waves shadow zone december 20, 2016 rawan239 most of the knowledge we have about earths deep interior comes from the fact that seismic waves penetrate the earth and are recorded on the other side. Some types of seismic waves travel through the interior of the earth and are detected by seismic stations on the other side of the earth. Earthquakes and earths interior flashcards quizlet. Seismic waves provide a probe of the earths deep interior, and their predictable behavior, as set out in chapters 3 and 4, makes it is possible to obtain highresolution models of some of the earths internal properties. Indirect sources of information about the earth s interior. Pdf refraction why do seismic waves travel a curving. A teachers guide designed to introduce the concepts of waves and seismic waves that propagate within the earth, and to provide ideas and suggestions for how to teach about seismic waves. Seismic stations located at increasing distances from the earthquake epicenter will record seismic waves that have traveled through increasing depths in the earth. Seismic waves, shadow zone of pwaves and swaves pmf ias. Includes activities on elasticity, demonstrating seismic wave types with the slinky, water waves in a wave tank, wave velocity, and the human wave demonstration. This worksheet has 3 multiple choice, 3 matching, 12 fill in. Just as the prism below refracts light at its faces, seismic waves bend, reflect and change speed at the boundaries between different materials below the earth s surface2.
From the study of seismic wave refraction and reflection, scientists infer earths internal structure by locating boundaries, or discontinuities, in its composition and physical properties. By analyzing these seismic waves, seismologists can explore the earth s deep interior. The longest period lowest order modes penetrate the core whereas higher order modes mainly sample the mantle. Basic overview of how they are used to determine the structure and properties of the layers of the earth. Ps4 waves and their applications in technologies for information transfer ps4. Seismology and earths interior body waves can travel deep. Variation of seismic velocities in the earths interior the velocity of seismic waves p and s waves advancing to the inside of the earth can be determined at various depths in th e knowledge. The lab acrobat pdf 91kb feb9 06 is also available in. Earthquakes and the earths interior tulane university. At significant distances from the epicenters, seismic waves are elastic waves. It provides an accurate measurement for small, nearby earthquakes. The division of the earth into the earth s crust, mantle and core, the later division into socalled bullen zones, or the latest laterally. Pdf seismic surface waves in laterally inhomogeneous earth.
Seismic waves are waves of energy that travel through the earths layers and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large humanmade explosions. Seismic waves generated in earths interior provide images that help us to better understand the pattern of mantle convection that drives plate motions. The relation between the propagation velocity of p and s waves and depth figure 3 has made it possible to identify a series of structural shells in the earth. Recognize the importance of seismic waves in the study of the earths interior. Jan 16, 2008 seismic waves generated in earths interior provide images that help us to better understand the pattern of mantle convection that drives plate motions. Seismic waves seismology is the study of earthquakes and seismic waves that move through and around the earth. Seismic body waves can be refracted and reflected just as sound and light waves are. The seismic waves are capable of reflecting the density variations in. Variation of seismic velocities in the earths interior the velocity of seismic waves p and s waves advancing to the inside of the earth can be determined at various depths in.
Since waves encounter different material like solid, molten they are used to guess the direction from which the waves occured from. Body waves, which are seismic waves that travel through the earth s inner layers, move at different speeds. We predict the emergence of two unique signatures, namely, a wave that would arrive almost simultaneously everywhere on earths free surface and the excitation of unusual spheroidal modes with a characteristic frequencyspacing in free oscillation spectra. The most important information on the constitution of the earth s interior has been obtained from studies of seismic body waves longitudinal and transverse seismic waves propagating through the earth. Differentiate the different types of seismic waves. Seismic wave propagation and earth models gfzpublic. Seismic waves and earths interior measuring and locating. The refraction or reflection of seismic waves is used for research into the structure of the earth s interior. Ppt earths interior powerpoint presentation free to. The asthenosphere is a region where seismic waves travel slowly. By analyzing these seismic waves, seismologists can explore the earths deep interior.
Understand that seismic waves travel through the earths interior triangulate the location of an epicenter based on the arrival times of p and swaves disciplinary core idea dci. Using seismic waves to image earths internal structure nature. Geologists all over the world have used this for more than 50 years. Dec 01, 2019 importance of understanding the interior of the earth understanding the structure of the earths interior crust, mantle, core and various forces heat, seismic waves emanating from it is essential to understand the evolution of the earths surface, its current shape and its future. S waves cannot travel through liquids, they can travel through solids. Sh waves are totally reflected at the free surface. Ppt types of seismic waves powerpoint presentation. Seismology and earths interior there are two categories of earthquake waves.
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