Source parameters of the earthquake, determined by using longperiod seismic waves a217 table 1. Stress arises because the fractured crust rides on a ductile mantle which slowly flows in convection currents. Surface waves unlike body waves, surface waves travel only near or at the surface of the earth. These waves resemble sound waves, since both are compressiondilatation or compression rarefaction waves. There are several different kinds of seismic waves, and they all move in. Produced by the national science teachers association, 1992. Natural disasters a natural disaster is the effect of anatural hazard e. These waves travel slower than both s and p waves, but have a higher amplitude and so can be the most destructive of all the seismic waves. Disasters disasters are hazards that cause destruction or environmental changes. Earthquakes and seismic waves barren county schools. Earthquakes have changed the shape of landmasses on earth for millions of years. When they encounter boundaries between different media, the waves react according to snells law, and the angle of refraction across the boundary will depend on the velocity of the second media relative to the first.
They are longitudinal waves which means that the direction of motion and propagation are the same. An earthquake releases two types of traveling seismic waves, called transverse and longitudinal waves. Surface waves cause the largest ground movements and the most damage. What is the difference between richter magnitudes and mercalli intensities. Three types of unequal stress on the earths crust are compression, tension, and shear. Seismic waves travel through the earth and follow the same laws of refraction and reflection as any other wave at interfaces. Shock waves can be felt on the other side of the earth. Surface waves in earthquakes can be divided into two types. Surface waves are seismic waves that travel through earths surface.
Three types of stress on the earths crust sciencing. Surface waves, the slowest earthquake waves, travel along the surface of the earth rather than down into the earth. As a current student on this bumpy collegiate pathway, i stumbled upon course hero, where i can find study resources for nearly all my courses, get online help from tutors 247, and even share my old projects, papers. Such waves correspond to ripples of water that travel across a lake. This lesson will describe the main types of earthquake waves, their properties, motion, and effectsincluding which cause the most damage. Compare and contrast seismic waves to ripples on water.
Favorite answer 1 structure of the earths interior. These earthquake waves, also called body waves, come in two distinct forms. Earthquake waves that pass through the interior of earth. When you toss a pebble into a pond, it creates radiating waves in the water. Earthquakewaves when earthquake occurring time, there will be many vibrations spreads outwards in all direction from the focus point, it is known as earthquake waves. P wave, the difference between p and s waves and p wave. When an earthquake occurs, waves are produced that travel outward away from the focus of the earthquake, in much the same way that ripples move across the surface of water when a pebble is thrown into a pond. 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. Earthquakes and volcanoes are evidence for plate tectonics.
Model a best represents the motion of earthquake waves called 1 pwaves compressional waves that travel faster than swaves shear waves shown in model b 2 pwaves compressional waves that travel slower than swaves shear waves shown in model b. Rayleigh waves are the surface waves responsible for the rolling or heaving during an earthquake. These are waves that travel through the surface of the earth. The other, less destructive types of waves present during an earthquake are primary and secondary waves. Swaves move like water waves through earths interior. Seismic waves refract and behave differently in different. L waves were named after a geologist who studied them. Earthquake shaking and damage is the result of three basic types of elastic waves. Effects of rayleigh and love waves on microtremor hv spectra.
Swaves on the other hand will completely stop and dissipate once they hit liquids. In these waves each particle vibrates to and fro in the direction of propagation. There are two types of body waves, called p waves and s waves. Among the many types of seismic waves, one can make a broad distinction between body. The richter scale is a rating of an earthquakes magnitude based on the size of the earthquakes seismic waves. Analyzing the types of waves produced by earthquakes. When stress builds up in rock, the rock breaks causing an earthquake. Seismic waves surface waves slowest cause the most damage move with an up and down and sidetoside motion. Seismic waves and earthquake location earthquake science center.
Its motion is the same as that of a sound wave in that, as it spreads out, it alternately pushes compresses and pulls. Explain that the amplitude of seismic waves is related to the amount of energy released from the source and decreases with distance from the source. The third general type of earthquake wave is called a surface wave, reason being is that its motion is restricted to near the ground surface. The types are natural disasters man made disasters 3. 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. When the plates fracture or slip, energy is released as seismic waves source. Video lecture describing speeds and paths of different seismic waves within earth from an earthquake to a distant seismic station. P waves are the fastest seismic waves and can move through solid, liquid or gas.
Seismic waves are fundamentally of two types, compressional, longitudinal waves or shear, transverse waves. Earthquake waves that pass through the interior of. The body waves, which penetrate deep into the earth and return to the surface bearing information about the interior, are of two types. The video describes and compares the four main types of seismic wavesp waves, s waves, love waves, and rayleigh waves. Pdf effects of rayleigh and love waves on microtremor h. The average speed of the transverse and longitudinal waves in rock are 9. A pwave is one of the two main types of elastic body waves, called seismic waves in. P waves are also called pressure waves for this reason. They make the ground roll up and down or shake from side to side. Base your answer to the following question on the diagram below, which shows models of two types of earthquake waves. By comparing the arrival times of the waves, scientists can determine the location of an earthquake many thousands of miles away.
They leave behind a trail of compressions and rarefactions on the medium they move through. Earthquake types and types of waves, its characteristics. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Which type of seismic wave is the most destructive. The plates of the crust collide in some places, pull apart in others, and sometimes grind against each other.
They are responsible for the strongest ground shaking and most of the damage to the built. Earthquakes mechanics and effects civil engineering. As civilization has grown and advanced, many towns and. Body waves traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake.
Introduction and types a wave is a transfer of energy through a medium from one point to another. 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. All three types of seismic wave are generated in an earthquake, and we can monitor them to find out about the nature of one. The wave equation to motivate our discussion, consider the onedimensional wave equation. An introduction to seismology, earthquakes, and earth. 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. Certain animals, such as dogs, can feel the p waves much before an earthquake hits the crust surface waves arrive. They can be either longitudinal rayleigh or transverse love and rayleigh. Before we can understand earthquakes, we first must explore deformation of rocks and faulting. This is the wave motion that is so damaging to structures.
Seismic waves are waves of energy that travel through the earths layers, and are a result of. Three types of waves carry the energy, p, s, and surface waves. Seismograms record ground motion and are used to locate quakes. Two basic types of elastic waves or seismic waves are generated by an. Page 310 earthquake causes and characteristics figure 38 source. Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. Seismic waves earthquakes discovering geology british.
This means that once these waves hit the liquid outer core of earth, pwaves are refracted and swaves are stopped. An introduction to seismology, earthquakes and earth structures is an introduction to seismology and its role in the earth sciences, and is written for advanced undergraduate and beginning graduate students. It is not the task of the new manual of seismological observatory practice nmsop, to. There are different types of waves, some move faster, slower, sideways, or up and down. P waves, also called compressional waves or primary waves, move through material by squeezing and stretching the material in the same direction as the wave is moving. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. Activity investigating the speed of earthquake waves. Although they are the slowest of all earthquake waves, l waves usually cause more damage to society than p or s waves. Earthquakes are caused when energy is released as the lithosphere crust and upper mantle of the earth moves. They are the energy that travels through the earth and is recorded on seismographs. Waves travel outward from the quake zone in all directions in a ripple effect propagation.
P waves, or primary waves are the first waves to hit the seismographs when an earthquake strikes. Within the earth rocks are constantly subjected to. Surface waves travel more slowly than the other types of seismic waves. Seismic wave demonstrations and animations 1 purdue university. Body waves are waves that travel through the earths interior. Seismic wave propagation and earth models gfzpublic. P waves are the first wave to hit the earths surface.
Start studying chapter 2 section 2 earthquakes and seismic waves. There are two types of seismic wave, namely, body wave. Physics question an earthquake releases two types of traveling seismic waves, called transverse and longitudin. Earthquakes radiate seismic energy as both body and surface waves. Dear anna, broadly speaking, there are two types of earthquake waves, namely body waves and surface waves. Surface waves are important, but they dont provide much information about what happens below the surface. There are 2 different types of shadow zones areas where these waves relative to the epicenter of the earthquake. If drainage is unable to occur, the tendency to decrease in volume results in an increase in pore pressure. The fundamentals of seismic wave propagation are developed using a physical approach and then applied to show how refraction, reflection, and teleseismic techniques are used to. The faster of these body waves is called the primary or p wave.
Surface waves are waves that travel close to the earths surface, like waves on a lake. When body waves reach the free surface of the earth some of their energy is converted into complex surface waves that are trapped near the surface of the earth and produce generally lower frequency ground motions. These waves are classified into three types they are primary waves, secondary waves, and long waves. For this, we need to study body waves so that we can see what earths body is like. An earthquakes magnitude is a number that geologists assign to an earthquake based on the earthquakes strength. After a sudden displacement of a large water volume by seismic activity earthquake, the ocean floor is raised or dropped and large tsunami waves can be formed by gravitational forces. The shifting rock in an earthquake causes vibrations called seismic waves that travel within earth or along its surface.
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