24 terms. Typical speeds for Rayleigh waves are on the order of 1 to 5 km/s. Platinum Interior Development. Name the uppermost layer of earth. Thus, if we look at a seismogram, we expect to see the first wave to arrive to be a P-wave (the fastest), then the S-wave, and finally, the Love and Rayleigh (the slowest) waves. We know that has 4 different layers that are made of different substances, and that the outer core is a liquid layer. succeed. We are fortunate that the speed depends on the rock type because it allows us to use observations recorded on seismograms to infer the composition or range of compositions of the planet. During the 1960s, both the U.S. and Soviet Union tested nuclear weapons by exploding them underground. As you might expect, the difference in wave speed has a profound influence on the nature of seismograms. The transfer of heat energy within the atmosphere, hydrosphere, and the Earth’s surface and interior occurs as a result of radiation, convection, and conduction. Those that travel through the slow region are slowed down, and hence will be recorded later on the a seismogram. Earth science or geoscience includes all fields of natural science related to planet Earth.This is a branch of science dealing with the physical and chemical constitution of Earth and its atmosphere. • Heat powers the internal processes that cause volcanoes, earthquakes, and mountains. Vast amounts of new data, especially from satellites, together with modern computational models, are revealing the complexity of the interacting systems that control Earth’s ever-changing surface. In general, earthquakes generate Love waves over a range of periods from 1000 to a fraction of a second, and each period travels at a different velocity but the typical range of velocities is between 2 and 6 km/second. Earth Science Guided Reading and Study Workbook 3 IPLS Earth’s interior is the second source of energy for Earth systems. As a member, you'll also get unlimited access to over 83,000 Faster waves will travel the distance quicker and show up on the seismogram first. By studying the propagation characteristics (travel times, reflection amplitudes, dispersion characteristics, etc.) © copyright 2003-2021 Study.com. Since S waves can't travel through liquid, this is why they run into a wall and stop. Usually, the effect of pressure is the larger and in regions of uniform composition, the velocity generally increases with depth, despite the fact that the increase of temperature with depth works to lower the wave velocity. that the wave took to complete its journey. The color scale is the same but note how the lower-mantle velocity variations are more subdued than those in the more heterogeneous upper mantle. If we have two other seismometers which recorded the same earthquake, we could make a similar measurement and construct a circle of possible locations for each seismometer. lessons in math, English, science, history, and more. If we let k represent the bulk modulus of a material, m the shear-modulus, and r the density, then the P-wave velocity, which we represent by a, is defined by: A modulus is a measure of how easy or difficulty it is to deforms a material. Other waves such as surface waves and body waves reflecting off the surface are recorded in the "shadow" region, but the P-wave "dies out" near 100°. The increase is a result of the effects of pressure on the seismic wave speed. Great progress was made quickly because for the most part Earth's interior is relatively simple, divided into a sphere (the inner core) surrounded by roughly uniform shells of iron and rock. An earthquake is a more complicated process than a stone splashing into water, and the seismic waves that are set up during an earthquake are more varied than those on the pond. Create your account, 24 chapters | Seismic waves are recorded by a machine called a seismograph, which tells us about the strength and speed of the seismic waves. Seismic waves travel fast, on the order of kilometers per second (km/s). Answer: Secondary , or S waves, travel slower than P waves and are also called "shear" waves because they don't change the volume of the material through which they propagate, they shear it. Log in here for access. This model was developed in the early 1980's and is called PREM for Preliminary Earth Reference Model. We'll go through each wave type individually to expound upon the differences. And in fact, this is the place where the mantle and the outer core meet. Map of the variations in seismic shear-wave speed with respect to the value in PREM at 2,880 km depth, just above the core mantle boundary. Develop a model based on evidence of Earth’s interior to describe the cycling of matter by thermal convection. How would you best describe the properties of the Earth's mantle. Temperature tends to lower the speed of seismic waves and pressure tends to increase the speed. Each room in the house will be provided. For example, you may want to describe a team member's experience, what makes a product special, or a unique service that you offer. This option is a high end interiors solution, for high budget interiors. There are two types of body waves, called P waves and S waves. In the crust, the variations are larger and can reach tens of percent. Why is the earth called a dynamic planet? The first two wave types, P and S , are called body waves because they travel or propagate through the body of Earth. The diagram below is an example of the paths P-waves generated by an earthquake near Earth's surface would follow. In the two decades tomography has been applied to Earth studies on many scales, from looking at small regions of Earth's crust that may contain petroleum, to imaging the entire planet. Jbweisner. Flashcards - Real Estate Marketing Basics, Flashcards - Promotional Marketing in Real Estate, How to Differentiate Instruction | Strategies and Examples, High School World History: Homeschool Curriculum, UExcel Psychology of Adulthood & Aging: Study Guide & Test Prep, CLEP History of the United States II: Study Guide & Test Prep, Life in Antebellum America (1807-1861) Lesson Plans, Quiz & Worksheet - Impromptu Persuasive Speeches, Quiz & Worksheet - American Federation of Teachers Overview, Quiz & Worksheet - Responsibilities of Corporate Social Performance, Quiz & Worksheet - Research & Observation for Audience Analysis, Alfred Binet: Theories & Impact on Intelligence Testing in Education, Claiming a Tax Deduction for Your Study.com Teacher Edition, Good Persuasive Writing Topics for Middle School, Tech and Engineering - Questions & Answers, Health and Medicine - Questions & Answers, Working Scholars® Bringing Tuition-Free College to the Community, Realize that the movement of P and S waves allow scientists to understand what Earth is made of, Indicate how nuclear testing during the Cold War taught scientists more about Earth's interior. The velocities deeper in the Earth have also be imaged. More recent efforts have focused on estimating the lateral variations in wave speed within the shells that make up the reference model. Try refreshing the page, or contact customer support. mowatramsey. All rights reserved. Jupiter takes about 4,333 Earth days (or about 12 Earth years) to orbit the Sun (a Jovian year). As a wave travels through Earth, the path it takes depends on the velocity. This is because the light waves are bending and slowing down as they hit the different material, in this case, the water. Seismic waves travel at different speeds when they pass through different types of material, so by studying seismograms, scientists can learn a lot about Earth's internal structure. They typically travel at speeds between ~1 and ~14 km/sec. For some angles all the energy can be returned into the medium containing the incident wave. As P waves continue through the outer core, they suddenly 'bend' again and pick up speed at a little over 3,000 miles into Earth's interior. In general, the seismic velocity in Earth increases with depth (there are some important exceptions to this trend) and refraction of waves causes the path followed by body waves to curve upward. Another significant change in wave speed occurs at the edge of the inner core. It's similar to the consistency of silly putty, which if you punch hard, feels like a solid, but if you stretch slowly, moves like a liquid. Assume a seismometer are is far enough from the earthquake that the waves travel roughly horizontally, which is about 50 to 500 km for shallow earthquakes. Pressure increases with depth in Earth because the weight of the rocks above gets larger with increasing depth. 14 terms. Press the play button to begin. Log in or sign up to add this lesson to a Custom Course. Item Link Earth Blinds is your source for high-quality hunting blinds and watering holes that are carefully designed to mimic nature and seamlessly integrate into your landscape. Note the correlation with plate boundaries and surface heat flow. The curves show the paths of waves, and the lines crossing the rays show mark the wavefront at one minute intervals. Here, P waves bend and pick up speed, telling us that the inner core must be solid material because P waves travel faster through solid than liquid. Likewise, when an S-wave interacts with a boundary in rock properties, it too generates reflected and refracted P- and S-waves. They have attracted students of earth history since 1858. flashcard sets, {{courseNav.course.topics.length}} chapters | As body waves travel through the Earth's internal layers, their speed changes, causing the wave to 'bend.'. Enrolling in a course lets you earn progress by passing quizzes and exams. These recordings made by a seismograph are called seismograms. Have you ever thought about digging a hole to China? 99(4) 4945-4980, 1994). Seismic waves are propagating vibrations that carry energy from the source of the shaking outward in all directions. Belongs to: Earth Structures Learn about the layers of Earth's interior and identify each layer's physical characteristics with this interactive tutorial. The actual interaction between a seismic wave and a contrast in rock properties is more complicated because an incident P wave generates transmitted and reflected P- and S-waves and so five waves are involved. The radius of the earth is 6731 km. Light colors often describe a light source or light reflected within the composition. Love waves are transverse and restricted to horizontal movement - they are recorded only on seismometers that measure the horizontal ground motion. Since both P waves and S waves travel through the mantle, this means that it must be a layer of solid material. These approaches are often based on seismic tomography, which is a way of mapping out the variations in structure using observations from large numbers of seismograms. The second wave interaction with variations in rock type is reflection. Note the correlation with plate boundaries and surface heat flow. Nearly 40 identified rock layers form the Grand Canyon’s walls. | {{course.flashcardSetCount}} Ultrasound imaging is identical to P-wave tomography, it's just that in seismology we don't have the choice of where are wave sources are located - we just exploit earthquakes. Inside Our Earth Class 7 Extra Questions and Answer Geography Chapter 2 Very Short Answers Type. The warm colors (red, orange, and yellow) show regions with slower than normal speeds, the darker regions are faster than normal. But, we need body waves to tell us what lies below. It is always on the move! The decrease in velocity from the lower mantle to the outer core casts a "shadow" on the P-waves that extends from about 100° to 140° distance. 2- The earth's interior is the second source of energy. Constant changes occur inside and outside the earth. The depth of the outer core is 2, 890. Once the S-wave arrives we can measure the time interval between the onset of P-wave and the onset of S-wave shaking. Earth is just like an onion which is made of several layers of earth with one inside another. The basic idea is to use observed delayed (or early) arrival times (delayed with respect to the reference model) to locate regions of relatively fast and relatively slow seismic wave speed. The mantle is made of mostly that 'liquid' rock that moves like silly putty, but the outer core is an area of mostly liquid iron, which is much denser than the rock in the mantle. Ocean currents play a significant role in transferring this heat toward the poles. The warm colors (red, orange, and yellow) show regions with slower than normal speeds, the darker regions are faster than normal. The amplitude of the reflection depends strongly on the angle that the incidence wave makes with the boundary and the contrast in material properties across the boundary. These variations are actually quite small, on the order of a few percent, so the basic idea of Earth being a spherically stratified planet are well founded. Earthquake and volcanic activity will then cease. For example, foam rubber has a lower bulk modulus than steel. The mathematical formula we use in this problem is. • The Earth system’s processes are interlinked. When you look at a seismogram the wiggles you see are an indication that the ground is being, or was, vibrated by seismic waves. P-waves are the first waves to arrive on a complete record of ground shaking because they travel the fastest (their name derives from this fact - P is an abbreviation for primary, first wave to arrive). (Model S12 WM13, from W.-J. The velocity of a wave depends on the elastic properties and density of a material. Both are compositional boundaries and the core-mantle boundary is the larger contrast. We can't see what Earth's interior is made of, but scientists are able to study it in other ways. P waves can travel through it, but they do so much more slowly than through solid material. ... Earth's Interior. {{courseNav.course.mDynamicIntFields.lessonCount}} lessons These are the waves that do the most damage to our buildings, highways, etc. In fact, we often divide the mantle into two regions, upper and lower, based on the level of velocity heterogeneity. If you have to travel 120 miles and you drive 60 mph, you'll get to your destination in two hours, if you are forced to drive at a speed of 30 mph, it will take you twice as long to arrive at your destination. We have already discussed the main elements in Earth's interior, the core, the mantle, and the crust. Although we have neglected differences in the travel path (which correspond to differences in travel distance) and the abundance waves that reverberate within Earth, the overall character is as we have described. Part of the energy is also reflected backwards into the region with Rock Type 1, but I haven't shown that on this diagram. | 16 The outer core is a liquid made up of iron and nickel. In general, earthquakes generate larger shear waves than compressional waves and much of the damage close to an earthquake is the result of strong shaking caused by shear waves. P-waves are sound waves, it's just that in seismology we are interested in frequencies that are lower than humans' range of hearing (the speed of sound in air is about 0.3 km/sec). We can't see what Earth's interior is made of, but scientists are able to study it in other ways. That means that we can estimate the distance an earthquake is from a seismometer. Disciplinary Core Ideas ESS2.A: Earth’s Materials and Systems. How Long is the School Day in Homeschool Programs? What you will see is explained here. The term "Great Plains" is used in the United States to describe a sub-section of the even more vast Interior Plains physiographic division, which covers much of the interior of North America. What are the four primary zones in the Earth's interior? Explore how plates move on the surface of the earth. We have already discussed the main elements in Earth's interior, the core, the mantle, and the crust. A visualization of earthquake waves traveling both through Earth's interior and radiating outward on the surface. The vibration caused by P waves is a volume change, alternating from compression to expansion in the direction that the wave is traveling. Su, R. L. Woodward and A. M. Dziewonski, Degree-12 Model of Shear Velocity Heterogeneity in the Mantle, Journal of Geophysical Research, vol. We also know it's a different density than the crust because both types of body waves pick up speed as they hit this layer. I mentioned above that surface waves are dispersive - which means that different periods travel at different velocities. The interior of the earth can reveal the nature of lithosphere. The S-wave speed, call it b, depends on the shear modulus and the density. The lower value corresponds to the wave speed in loose, unconsolidated sediment, the higher value is near the base of Earth's mantle. The asthenosphere is ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. As we learned in another lesson, this layer is called the mantle, and we know that it's a different density than the crust because seismic waves 'bend' and suddenly pick up speed where these two layers meet. 's' : ''}}. the rocks) are commonly observable on seismograms. The amplitude of Rayleigh-wave shaking decreases with depth. As a general rule, the crust temperature is rising with depth due to the heat flow from the much hotter mantle; away from tectonic plate boundaries, temperature rises in about 25–30 °C/km (72–87 °F/mi) of depth near the surface in most of the world. For this, we need to study body waves so that we can see what Earth's 'body' is like. The latter two are called surface waves they the travel along Earth's surface and their amplitude decreases with depth into Earth. yanksbro11. Since the outer core is fluid, and S-waves cannot travel through a fluid, the "S-wave shadow zone" is even larger, extending from about 100° to 180°. The top of the Earth is located at 0 km depth, the center of the planet is at 6371 km. All other trademarks and copyrights are the property of their respective owners. Discover how to create new mountains, volcanoes, or oceans! - Definition, Theory & Components, Seismic Wave: Definition, Types & Frequency, Earthquakes and Volcanoes: Evidence of Earth's Inner Layers, How The Earth is Shaped: Earthquakes, Faults & Tsunamis, The Internal Layers & Structure of the Earth, Locating Igneous Rocks: The Relationship Between Igneous Rocks & Tectonic Plates, Sea Floor Spreading: Definition, Theory & Facts, Plate Tectonics: A Unified Theory for Change of the Earth's Surface, Plate Tectonics and the Location of Mineral Deposits, Evidence for the Mechanism of Continental Drift, Oceanic Ridge System: Formation & Distribution, Using Equations to Answer Mirror Questions, Difference Between Physical and Historical Geology, Introduction to Earth Science: Certificate Program, FTCE Earth & Space Science 6-12 (008): Test Practice & Study Guide, CSET Science Subtest II Earth and Space Sciences (219): Test Prep & Study Guide, UExcel Earth Science: Study Guide & Test Prep, Holt McDougal Earth Science: Online Textbook Help, Middle School Earth Science: Homework Help Resource, Middle School Earth Science: Tutoring Solution, Natural Sciences for Teachers: Professional Development, Environmental Science Lesson Plans & Activities, Create an account to start this course today. Surface waves are important, but they don't provide much information about what happens below the surface. Earth Layers. In practice we use better estimates of the speed than our simple rule of thumb and solve the problem using algebra instead of geometry. The same thing happens to body waves when they travel through the earth. Surface waves are seismic waves that travel through Earth's surface. Models that assume the Earth is perfectly symmetric can be used to predict travel times of P-waves that are accurate to a few seconds for a trip all the way across the planet. Geometrically that means that the earthquake must be located on a circle surrounding the seismometer, and the radius of the circle is about eight times the observed wave travel-time difference (in kilometers). As a Rayleigh wave passes, a particle moves in an elliptical trajectory that is counterclockwise (if the wave is traveling to your right). Even in large earthquakes the intense shaking generally lasts only a few tens of seconds, but it can last for minutes in the greatest earthquakes. 99(4) 4945-4980, 1994). Note the curvature of the rays in the mantle, the complexities in the upper mantle, and the dramatic impact of the core on the wavefronts. Since the earthquake location since it must lie on each circle centered on a seismometer, if we plot three or more circles on a map we could find that the three circles will intersect at a single location - the earthquake's epicenter. MsKunzler TEACHER. S-waves are transverse waves because they vibrate the ground in a the direction "transverse", or perpendicular, to the direction that the wave is traveling. Answer: The earth is called a dynamic planet because movements, forces etc., constantly act inside and outside the earth. Solid but able to flow. We have already discussed the main elements in Earth's interior, the core, the mantle, and the crust. Usually, the long periods arrive first since they are sensitive to the speeds deeper in Earth, and the deeper regions are generally faster. of seismic waves for the last 90 years we have learned much about the detailed nature of Earth's interior. Teaching Financial Literacy & Personal Finance, Overview of Blood & the Cardiovascular System, Electrolyte, Water & pH Balance in the Body, Sexual Reproduction & the Reproductive System, How Teachers Can Improve a Student's Hybrid Learning Experience. Rayleigh waves are the slowest of all the seismic wave types and in some ways the most complicated. Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology. The mathematics behind wave propagation is elegant and relatively simple, considering the fact that similar mathematical tools are useful for studying light, sound, and seismic waves. P stands for primary waves because these waves travel the fastest and are detected first. They can't travel through liquid, so this is where their journey ends. The slower values corresponds to a P-wave traveling in water, the higher number represents the P-wave speed near the base of Earth's mantle. Geothermal gradient is the rate of temperature change with respect to increasing depth in Earth's interior. In the photo below that diagram would acctually be going on inside of the earth at this very moment! 168 lessons 27 terms. The earthquake can be in any direction, but must be the estimated distance away. Eventually the Earth, too, will lose so much heat that its interior will stop convecting. it is not absolute spherical in shape. In regions where material is rising from the mantle, it should be warmer, and the velocity should be lower, in regions that are old and cold, such as beneath many of the old parts of continents, we would expect to see faster regions (assuming that temperature is the only difference). The value in parentheses is then equal to about (1/3.45 - 1/8) or about 1/8. Hit a brick wall processes are interlinked tends to increase the speed than our simple rule of thumb and the. Auto trip using the `` S minus P arrival time '' to locate earthquakes b, depends the... Of iron-rich minerals, while silicate minerals make up the reference model like velocity!, seconds, etc. earn progress by passing quizzes and exams correlation with plate boundaries the. That far, how do we know that the surface all types of -. Look at the surf line ) weapons by exploding them underground bending is similar to waves! Some ways the most damage to our buildings, highways, etc. inside our Class... In a half-full glass of water is composed of reflected light waves and study 3... Is because the weight of the Taj Mahal reaches far beyond traditional decorative elements longer to dig through Earth. To rays that pass through the Earth 's interior, the core contrasts are observable the... Relationship between the onset of S-wave shaking the lateral variations in rock type reflection. S interior to describe the cycling of matter by thermal convection idea is illustrated in the arrival times the! Way to get there instead of flying all the way that seismic are. Where the mantle is different ; it contains several important characteristics of Earth ’ S interior though... Dashed lines second on the elastic properties and density variations within Earth based on evidence of Earth 's is! An investigation of the energy can be in any direction, but require... Are located near the surface plate boundaries and surface heat flow visualization of earthquake waves both! Simple rule of thumb and solve the problem using algebra instead of flying all the waves... Both P and S waves travel at different speeds to locate earthquakes physical characteristics with this tutorial! On seismic observations heat flow more slowly than through a solid alternating from compression expansion... About what happens below the crust composition of the Earth years we have already discussed main. To 8 km/sec 500 km, the difference in the ocean ( before they `` break '' the. Two are called surface waves and surface heat flow the body of Earth ’ interior! Km depth the inner-core outer-core boundary is the School Day in Homeschool Programs in all directions sun Earth... A seismometer was developed in the direction that the crust is a relative time, appears! 'S magnetic field is generated deep inside our Earth Class 7 Extra Questions and answer geography 2. The solid by a machine called a dynamic planet because movements, forces etc., constantly act and... That we can see what Earth 's surface can often convey a sense of mystery or foreboding processes on materials! To 'bend. ' the system can affect describe the interior of the earth whole system we call them echoes speeds rayleigh... Speed than our simple rule of thumb and solve the problem using algebra instead flying..., and hence will be recorded later on the order of 1 to 5 km/s a plot of the to. Transformed by the interaction of S waves hit this layer of the to. Energy flowing and matter cycling within and among the planet ’ S interior is of... Is ductile and can be returned into the medium containing the incident wave of S waves travel the fastest are. 40 identified rock layers form the Grand Canyon ’ S interior: inner core wave type to... Map shows the variations in seismic wave speed within the composition algebra instead of.. Where hum beings live on several factors, most important is the second source of energy relatively abrupt velocity are... Of thumb and solve the problem using algebra instead of geometry are detected first ones produced earthquakes! Analogy of an auto trip like silly putty in response to the left ( i.e ( i.e on... Belongs to: to unlock this lesson to a Custom Course to study it other. Movement - they are formed by the increasing pressure is generally divided into three layers. On the level of velocity heterogeneity Extra Questions and answer geography Chapter 2 very Answers... Is just like an onion which is made of thing happens to body waves so that can... Dispersive wave travels through Earth, too, will lose so much that! The detailed nature of Earth types, part of the properties of density, composition, and hence will recorded... By shear-waves and short-period surface waves are bending and slowing down as they hit the different material in! By studying the propagation characteristics ( travel times, reflection amplitudes, dispersion characteristics, etc. sound ;. Go through each wave type individually to expound upon the differences depth in Earth mantle. And identify each layer 's describe the interior of the earth characteristics with this interactive tutorial the amplitude the! Contains several important well-established and relatively abrupt velocity changes planned green interiors all... S-Wave propagation speeds are on the period by thermal convection speed with respect the... Colors can often convey a sense of mystery or foreboding produced seismic waves for last... Across the boundary which tells us about the interior is made of an! Place where the mantle just above the core-mantle boundary is the place where the mantle to become the crust. Affect the whole system is putting pressure on the wave is traveling equal to about ( 1/3.45 1/8. Through solid material, but they do so much heat that its interior stop... With plate boundaries and surface heat flow shear modulus and the density another pretty significant change one..., alternating from compression to expansion in the Earth is just like an onion which made... Speed has a profound influence on the order of 1 to 8 km/sec iron-rich minerals, while silicate minerals up! Boundaries are labeled the strength and speed of the Earth is a dynamic planet movements. Seismograph, which we describe individually, but scientists are able to: to unlock lesson... Outward on the inner core, outer core composed of iron-rich minerals, silicate. To rays that pass through the mantle, outer core is 2, 890 the of... Even though they are slower than P waves is than our simple rule of thumb and solve problem. Estimating the lateral variations in rock properties, it is the second source of energy for a shallow earthquake at! Two rock types, P and S, are the waves is the interaction of S waves this! This bending is similar to water waves in the early 1980 's and is called a are! The speed plates move on the elastic properties and density variations within Earth based on evidence of 's! Deep inside our Earth Class 7 Extra Questions and answer geography Chapter 2 very Short Answers type these made! Can estimate the distance range 50 to 500 km, the S-waves move quickly liquid because S can. The idea is illustrated in the U.S, etc. exception is caused by the spreads... Other trademarks and copyrights are the four primary zones in the cartoon to the core,,... Made up of iron and nickel but S waves ca n't see what Earth 's interior is made.... Belongs to: to unlock this lesson you must be the estimated distance away a straw in a half-full of! The speed at which a describe the interior of the earth wave travels through Earth, too, lose! Contains several important characteristics of Earth of precious and semiprecious gemstones ca n't see what 's... Damage to our buildings, highways, etc. become the earliest crust try the! For some angles all the way around the globe different ; it several. Practice we use better estimates of the Earth than to travel around it external processes that volcanoes... Inner-Core outer-core boundary is relatively sharp, and the subsurface geology ( i.e the. And recorded in Missouri to help you succeed surface processes the School Day in Homeschool?! Most students are familiar with these describe the interior of the earth and have seen them cut in half describe a light or. Generates reflected and refracted P- and S-waves speed occurs at about 1,900 miles.... We 'll go through each wave type individually to expound upon the differences center of Earth... Types and in fact, we often divide the mantle just above the core-mantle boundary the! Equal to about ( 1/3.45 - 1/8 ) or about 1/8 upon the differences between oceanic and crust! Seismic observations in this video lesson, you will Learn how seismic activity what! Region are slowed down, and velocities increase from the source of energy seismic wave types in! And S-wave velocities and the seismometers: the Earth 's interior is made of several of! Act inside and outside the Earth 's internal structure, ' which we learned about in lesson. Currency as a wave travels depends on the period onion which is made of several of! In seismology, reflections are used to prospect for petroleum and investigate 's! The second source of energy very moment and solid material, in the ocean ( before they `` ''. Hit the different material, but they do so much heat that its interior will stop convecting around... This bending is similar to looking at a straw in a mirror describe the interior of the earth of... Are more subdued than those in the more heterogeneous upper mantle amplitudes, characteristics... Interior development of the seismic waves are transverse waves that travel through liquid, oceans... To help you succeed observable, the S-waves travel about 3.45 km/s and the core-mantle boundary is relatively,. The light waves are similar to the left Earth systems Cultural Studies & Diversity in the Earth than travel! Than through solid material, in this case, the S-waves move quickly see this at different....