Geologists first study data from seismographs, this shows what kinds of seismic waves the earthquake produced and how strong they wereit also helps geologists infer how much movement occurred along the fault and the strength of the rocks that broke when the fault slippedthey use all this info to rate the quake on the m. Seismologists use seismic waves to learn about earthquakes and also to learn about the earths interior. The farther away the epicenter is, the greater the difference between the two arrival times. Information on teaching about seismic waves and demonstrations of seismic wave characteristics using a slinky are provided at. Pdf seismic waves and seismic barriers researchgate. Seismic waves are studied by geophysicists called seismologists. A seismic wave is a wave that travels through the earth, most often as the result of a tectonic earthquake, sometimes from an explosion. Identifying and understanding earthquakes using seismic activity. As they travel through earths in terior, seismic waves do not follow straight paths. Further information on seismic waves, wave propagation in the earth, and visualizations of seismic waves can be found in bolt 1993, p. The epicenter was near mineral, va, but the tremor shook homes, schools, and office buildings in washington, dc, including smithsonian institution buildings, and beyond. Some activities of man including use of explosives and mechanical methods e.
They are much slower than body waves, therefore they arrive after body waves. Students learn about the types of seismic waves produced by earthquakes and how they move the earth. When an earthquake strikes, p waves arrive at a seismograph first and s waves next. A seismograph is an instrument that records and measures. The three types of seismic waves are primary waves, secondary waves and surface waves. Surface waves are the slowest seismic waves and travel outward on the earths surface from the epicenter much like ripples do from a stone thrown into water figure 3. Seismic wave propagation and earth models gfzpublic. Seismic waves can cause earthquakes and have destructive capability. Earthquakes generate four principal types of elastic waves. They are the energy that travels through the earth and is recorded on seismographs. By carefully examining these seismic wave fronts and their propagation, the seismic waves tool illustrates how earthquakes can provide evidence that allows us. Seismic waves can then be recorded as wiggly lines by pen and ink on paper wrapped around a rotating drum.
Seismic waves viewer incorporated research institutions. The richter scale is a rating of an earthquakes magnitude based on the size of the earthquakes seismic waves. The degree of elasticity determines how well they are transmitted. A typical recording of an earthquake records a typical train of seismic waves. Depending on nature of seismic waves that are most probable in a specific. Seismic waves click here to a msword version of this page. P waves the first kind of body wave is the p wave or primary wave. The earthquake vibrations are waves of energy that radiate through earth away from the focus. Using the information you learned about seismic waves and label the first drawing as a p wave or an s wave. When the plates fracture or slip, energy is released as seismic waves source. Seismic phases and 3d seismic waves main seismic phases. Within this type of waves can be differentiated two forms, referred to as rayleigh waves and love waves in honor to the scientists who theoretically demonstrated its existence. When stress builds up in rock, the rock breaks causing an earthquake. Seismic waves are waves of energy that travel through the earths layers, and are a result of.
Seismic waves are usually generated by movements of the earths tectonic plates but may also be caused by explosions, volcanoes and landslides. An earthquake is the shaking that results when rocks move inside earth. Seismic waves and earthquake location earthquake science center. In this lesson, you will learn what seismic waves are, the various types of seismic waves, and their frequencies. There are several different kinds of seismic waves, and they all move in different ways. However, where a free surface is present like the earthair interface these two types of. The december 26, 2004 sumatra earthquake is chosen as the source of seismic waves but this lesson can be adapted to a dozen other large earthquakes. The seismogram recorded at station a would show the 1 arrival of p waves, only 2 arrival of s waves before the arrival of p waves 3 greatest difference in the arrival times of p waves and s waves. We present a concise naming scheme for seismic waves and an overview of the features of the seismic wavefield on europa, titan, ganymede. Use target reading skills as you read about seismic waves, complete the graphic organizer by. Through the body of the earth these are called pwaves for primary because they are fastest and swaves for secondary since they are slower. Seismic wave fields are recorded by a seismometer, hydrophone in water, or accelerometer. Earth material must behave elastically to transmit them.
Earthquakes and seismic waves pages 5157 types of seismic waves pages 5253 key concept. Body waves p waves compression wave the first kind of body wave is the p wave or primary wave. The results resemble those of predicted travel time curves from prem preliminary reference earth model, by dziewonski and anderson 1 seismic phases and 3d seismic waves. An earthquake occurs when earths surface shakes because of the release of seismic energy following the rapid movement of large blocks of the crust along a fault. During an earthquake two main types of waves are generated. The pwave motion, same as that of sound wave in air. Compressional p and shear s waves propagate through the earths interior and are known as body waves.
First the p waves, followed in succession by the s and surface waves. A wave of energy that is generated by an earthq uake or other earth vibration and that travels w ithin the earth or along its surface. There are two types of seismic wave, namely, body wave. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. Wave type and names particle motion other characteristics p, compressional, primary, longitudinal alternating compressions pushes and dilations pulls which are directed in the same direction as the. An earthquake has different types of waves that it sends out. Learn vocabulary, terms, and more with flashcards, games, and other study tools. On longitudinal waves in two contacting media 35 5. A seismograph, or seismometer, is an instrument used to detect. 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.
Seismic stations a, b, and c received the data used to locate the earthquake epicenter. Because of the elastic properties of earth materials rocks and the presence of the earths surface, four main types of seismic waves propagate within the earth. Wave type and names particle motion other characteristics p, compressional. P waves and s waves arrive almost simultaneously at a seismograph station the velocity of seismic waves increases as the waves cross the b. The importance of seismic wave research lies not only in our ability to understand and predict earthquakes and tsunamis, it also reveals information on the earths composition and features in much the same way as it led to the discovery of mohorovicics discontinuity. Earthquake vibrations seismic waves can be initiated by a number of subsurface actions including movement along faults, and volcanic activity. Learn about the types of seismic waves and how they move. Seismograms record ground motion and are used to locate quakes. Shear waves on the other hand have larger amplitudes and travel at a slower speed, and move from side to side or up and down. An earthquakes magnitude is a number that geologists assign to an earthquake based on the earthquakes strength. Because compression waves travel at a faster speed they are also know as primary waves or p waves.
P waves, known as primary waves, are also part of a seismic wave. When an earthquake occurs, the shockwaves of released energy that shake the earth and temporarily turn soft deposits, such as clay, into jelly liquefaction are called seismic waves, from the greek seismos meaning earthquake. This is the fastest kind of seismic wave, and, consequently, the first to arrive at a seismic station. Easytouse controls speedup, slowdown, or reverse the wave propagation. Although an earthquake occurs, a seismograph station receives no seismic waves. The december 26, 2004 sumatra earthquake is chosen as the source of seismic waves but this lesson can be. Despite some similarities which water waves and seismic surface waves. Start studying earthquakes and seismic waves study guide. Sep, 2012 students investigate how seismic waves travel through earths internal layers and bounce and bend at internal boundaries between mantle, outer core, and inner core. At all distances from the focus, mechanical properties of the rocks, such as incompressibility, rigidity, and density, play a role in the speed with which the waves travel and the shape and duration of the wave trains. These are stacked data records from many event and station pairs. The two types of seismic waves described in plate tectonics, pwaves and swaves, are known as body waves because they move through the solid body of the earth. A seismic wave is an elastic wave generated by an impulse such as an earthquake or an explosion.
The propagation velocity of seismic waves depends on density and elasticity of the medium as well as the type of wave. A seismologist is a scientist who studies earthquakes and seismic waves. They create most of the damage at the surface because they are the waves that produce the most ground movement and pass through an area the most slowly. You will learn about p waves, s waves, rayleigh waves and love waves. As our theoretical understanding of the physics behind seismic waves has grown, physical and numerical modeling have greatly. Three types of waves carry the energy, p, s, and surface waves. Compression waves have small amplitudes and can travel at around 4. Temperature tends to lower the speed of seismic waves and pressure tends to increase the speed. The two main types of waves are body waves and surface waves. Terms in this set 21 name the three types of seismic waves. Explain that the amplitude of seismic waves is related to the amount of energy released from the source and decreases with distance from the. Epicenter determination, seismic waves, and hazards introduction earthquakes are vibrations of earth caused by large releases of energy that accompany volcanic eruptions, explosions, and movements of earths crust along fault lines.
Earthquakes and seismic waves this section explains how energy from an earthquake travels through earth, how it can be detected, and how the size of an earthquake can be measured. Seismic waves seismic waves radiate from a break or movement in the earths crust and can cause damage. Similar waves, which are generated by earthquakes, artificial explosions and analogous sources, and prpagate along the earths surface, are referred to as seismic surface waves. Information on teaching about seismic waves and demonstrations of seismic wave characteristics using a. Seismic waves may travel either along or near the earths surface rayleigh and love waves or through the earths interior p and s waves. The map below shows the location of an earthquake epicenter in new y york state. Seismic wave propagation in icy ocean worlds arxiv. Seismic waves carry energy from an earthquake away from the focus, through earths interior, and across the surface.
The velocity of rayleigh waves in this medium, c, is slightly less than the transverse wave velocity, c 0. From earthquakes to music is a 2hour interactive program that we use to present seismology in an approachable way. You will learn about pwaves, swaves, rayleigh waves and love waves. Students investigate how seismic waves travel through earths internal layers and bounce and bend at internal boundaries between mantle, outer core, and inner core. Primary and secondary waves are known as body waves, and these waves penetrate the interior of the earth, whereas surface waves do not penetrate the earth. Seismic wave propagation in stratified media brian kennett. Seismic waves seismology is the study of earthquakes and seismic waves that move through and around the earth. Earthquakes an earthquake is shaking or trembling of the earths surface, caused by the seismic waves or earthquake waves that are generated due to a sudden movement sudden release of energy in the earths crust shallowfocus earthquakes or upper mantle some shallowfocus and all intermediate and deepfocus earthquakes. Schmidts experiment and the theory of characteristics 25 3. They are the most destructive of seismic waves and are responsible for almost all of the damage that occurs because of an earthquake. Faults are breaks in the crust that may be hundreds of kilometers long and extend downward 10 to 20 km 612 miles into the crust.
Seismic waves earthquakes discovering geology british. The precise speed that a seismic wave travels depends on several factors. Seismic wave, vibration generated by an earthquake, explosion, or similar energetic source and propagated within the earth or along its surface. Seismic wave speed seismic waves travel fast, on the order of kilometers per second kms. It is intended to give the audience an indepth explanation about earthquake physics and how energy is carried through the earth by seismic waves.
This time difference tells scientists how far from the seismograph the epicenter is. When you toss a pebble into a pond, it creates radiating waves in the water. The dangers of earthquakes are presented as well as the necessity for engineers to design structures for earthquakeprone areas that are able to withstand the forces of seismic waves. These waves are of a higher frequency than surface waves. Its like when youre teacher loses their marbles because youve asked them the same question 7 times in a row. Earthquakes and seismic waves barren county schools. S waves cannot travel through liquids, they can travel through solids. The layering of the rocks and the physical properties of surface soil also affect wave characteristics. Seismic wave propagation in stratified media oapen. Geologists use seismic waves to locate an earthquakes epicenter. Seismic waves are fundamentally of two types, compressional, longitudinal waves or shear, transverse waves. Seismic waves can be defined as, the waves of energy caused by the sudden breaking of rock within the earth or an explosion1. The p wave can move through solid rock and fluids, like water or the liquid layers. Equations of motion and boundary conditions for the propagation of seismic waves in a nondispersive medium 30 4.