Learn more about the causes and effects of earthquakes in this article. Develop understanding of the structure of the earths interior and ultimately, relationships to plate tectonics, occurrence of earthquakes. About 95% of all earthquakes occur in the circumpacific belt coastal regions of chile, central america, indonesia, japan, and alaska and along the alpinehimalayan belt europeasia. Earthquakes and earth structure geological society, london. Within the earth rocks are constantly subjected to forces that. An earthquake, or seismic event, is a sudden movement of earths crust that releases energy. That activity builds stress and creates earthquakes.
These vibrations travel laterally as surface waves. The earth, the crust, the mantle, the core, continental crust, oceanic crust, upper mantle, lower mantle, inner core, outer core, lithosphere 865 km thick 2900 km thick 3480 km thick 5500. As discussed all earthquakes are relatively shallow. As discussed all earthquakes are relatively shallow, with the deepest at about 700 km depth. Over 14,000 residents of the region were killed as poorly constructed. The pdf portable document format versions of the lecture notes are optimized for printing. Exploring geology and evolution, 7e instructors manual chapter 9. It is given fact that the radius of earth is 6,370 km. Earthquakes teacher notes and student activities ga.
The second presentation covers earthquake hazards and tsunamis. Earthquakes and earths interior what causes earthquakes. Large amount of heat was generated by this fusion, and slowly as the. Earthquakes and earths interior summary abrupt movements of faults that release elastically stored energy cause earthquakes elastic rebound. Learning earthquake tip 1 earthquake design and construction. The usgs earthquake hazards program is part of the national earthquake hazards reduction program nehrp, established by congress in 1977, and the usgs advanced national seismic system anss was established by congress as a nehrp facility. The first covers the basics of earthquakes and seismology. It is a large fault zone that separates two great sections of earths crust. Pdf earth is a very unique planet in the solar system. There is a large amount of geologic activity and movement along the borders of these plates.
Earthquakes are the sudden shaking and vibrating of the earths crust as a result of a rapid release of energy when rocks break and move along faults. Seismic waves and earths interior earthquakes and plate. Earthquakes can happen when there is a large amount of. Explain the elastic rebound theory, which provides an explanation for the origin of earthquakes. Although earthquakes cause death and destruction through such secondary. Focus and epicenter the point within earth where the earthquake starts is called the focus. Earthquakes teacher notes and student activities ga record. Earthquakes are caused by slippage along a break in the lithosphere, called a fault. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. 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. Seismographs are instruments that record earthquake waves.
Physical geology by steven earle used under a ccby 4. Therefore, the stress on rocks near the surface builds until the rocks break, and an earthquake occurs. A fault is a fracture or crack in the rocks where one side has moved relative to the other figure 1. The mild motion of a small seismic event can be exciting. The other main risk from earthquakes is the generation of tsunami. The usgs and its partners monitor and report earthquakes, assess earthquake impacts and. Geology 12 earthquakes and earths interior earth science x. Earthquakes can happen when the strain on weak rocks forces them to break and fracture. They are solid bodies developed out of materials same as, or similar to, our planet. Its like when youre teacher loses their marbles because youve asked them the same question 7 times in a row. Many earthquakes happen at the borders of tectonic plates. Surface rocks respond to stress by elastic bending called strain. Earth s layers can be examined indirectly, such as by studying earthquakes, magnetism, gravity, and heat flow and by applying the laws of physics. Energy moves outward as an expanding sphere of waves.
Major tectonic plates on the earths surface the earth and its interior long time ago, a large collection of material masses coalesced and formed the earth. Realtime notifications, feeds, and web services get realtime earthquake notifications sent to you on your phone or by email, or subscribe to realtime feeds. Travel times of p and s waves through earth vary depending on the properties of the materials 2. Explain how the materials in earths interior affect seismic waves. The material and the structure observed in the meteors are similar to that of the earth. Oct 29, 2015 geology 12 earthquakes and earth s interior earth science x. Also, since earth has a magnetic field, there must be metal within the planet. Focus is the point within earth an earthquake is the vibration of earth produced by the rapid release. The earths interior earth and planetary science university of. While many countries have borders along faults and mountain ranges, earthquakes dont care about political boundaries. Vibration of earth produced by the rapid release of energy 2. 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. Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another.
Field investigations determined that during this single earthquake, the pacific plate. Earthquake tip 1 learning earthquake design and construction figure 3. Chapter 8 earthquakes and earths interior section 1 what is an earthquake. Earthquake earthquake methods of reducing earthquake hazards. The constitution of the interior of the earth, as revealed by. The focus and epicenter of an earthquake can be located by measuring the differences in travel times between p and s waves. This gives most important evidences of interior of earth. Although earthquakes cause death and destruction through such.
List the key observations that revealed earth to possess a. Earthquakes and the earths interior earthquakes earthquakes occur when energy stored in elastically strained rocks is suddenly released. Our direct knowledge of earth s interior is limited to the first few tens of kilometers immediately below the surface. This fact sheet uses data from the 1994 magnitude 6. For example, p waves travel fastest through materials that are very. This section explains what earthquakes and faults are and what causes earthquakes. Such knowledge is needed to predict ground motions in future earthquakes so that earthquakeresistant structures can be designed. The diagram to the left figure 31, which is the same as figure 9. What you feel as an earthquake is the sudden movement of the ground, which releases stored energy. Geology 12 earthquakes and earths interior youtube. Also, the origin of many phenomena like earthquakes, volcanoes, tsunami etc are linked with the structure of earths interior. The composition of the material through which p waves and s waves travel affects the speed and direction of the waves. An earthquake is the vibration of earth produced by the rapid release of energy within the lithosphere. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
But its properties are studied indirectly by deducing conclusions from the study of earthquake waves that propagate through the interior rocks and other such indirect means. Chapter 8 earthquakes and earths interior section 8. Mar 24, 2020 earthquake, any sudden shaking of the ground caused by the passage of seismic waves through earths rocks. As you might imagine, only body waves can give us any information about the deep interior of the earth. 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. Evidence on the structure and composition of the earths interior comes from 1 observations of surface rocks, 2 geophysical data from earthquakes, flow of. Earthquakes and the earths interior tulane university. The configuration of the surface of the earth is largely a product of the processes operating in the interior of the earth. Vibrations earthquakes occur as rock elastically returns to its. Earthquake energy also causes earth s surface to vibrate. It is the outermost solid and brittle part of the earth.
Understanding the basic structure of earth is very important to learn higher concepts well. Earthquakes and earths interior free download as powerpoint presentation. In this article geography section, we discuss the interior of the earth. Other clues to earths interior includes the fact that we know that earths overall density is higher than the density of crustal rocks, so the core must be made of something dense, like metal. Earthquake, any sudden shaking of the ground caused by the passage of seismic waves through earths rocks. Therefore, the interior of earth can not be studied only by direct observations. Search earthquake catalog view historic seismicity, find past earthquakes that meet your criteria. Vocabulary earthquake focus epicenter fault elastic rebound hypothesis aftershock foreshock each year, more than 30,000 earthquakes occur worldwide that are strong enough to be felt. Reading strategy building vocabulary as you read this section, write a definition for each vocabulary term in your own words. Over the course of geological time, earthquakes, floods, and other natural events have helped to shape the surface of our planet.
By analyzing these seismic waves, seismologists can explore the earths deep interior. Of all regions of the earth none invites speculation more than that which lies beneath our feet, and in none is speculation more dangerous. We shall look into the details of earthquake laters on. Earthquakes and the earths interior a violent pulse. Use the green headings as the main topics and the blue headings as subtopics. The interior of the earth can be understood only by indirect evidences as neither any one has nor any one can reach the interior of the earth. Plates, earthquakes and volcanoes maite cozar activity 5 fill the mindmap with the words below. What can earthquakes tell us about the interior of the earth. The deadly izmit earthquake struck northwest turkey on august 17, 1999, at 3 a. When an earthquake occurs the seismic waves p and s waves spread out in all directions through the earths interior. Earthquakes occur when energy stored in elastically strained rocks is suddenly released. Earthquakes and the earth s interior earthquakes earthquakes occur when energy stored in elastically strained rocks is suddenly released.
The presentation about earthquakes is divided into 2 separate discussions. Earthquakes are often caused by slippage along a break in the lithosphere, called a fault. Also, the seismic waves from earthquakes can be used to image the deep interior of the earth, providing vital clues to the internal structure of our planet. The focus is the point on the fault surface where motion begins. Powerpoint click to download the ms powerpoint file 10. Chapter 8 earthquakes and earth s interior section 8. Energy released at an earthquakes focus radiates outward as body waves, which are of two kinds.
Defining an earthquake defining an earthquake an earthquake is a natural occurrence, like rain. They can be used on the earths surface or buried text pp 222228 underground. Most of our knowledge of earths interior comes from the study of p and s earthquake waves 1. Hence, this becomes yet another source of information about the interior of the earth. Earthquakes from the link above, color in each state with the appropriate color from your key in order to represent how many earthquakes of magnitude 3.
Earthquake methods of reducing earthquake hazards britannica. Energy waves from large earthquakes can move through large portions of the earth. Various output formats, and links to earthquake details. Considerable work has been done in seismology to explain the characteristics of the recorded ground motions in earthquakes. Reading strategy outlining as you read, fill in the outline with the important ideas in this section. This waveform energy can be measured around the globe. The constitution of the interior of the earth, as revealed. Tsunami were primarily responsible for most of the 280,000 deaths in one of the earths deadliest earthquakessumatra, 2004and for most of the tens of billions of dollars in damage in one of the earths costliest earthquakestohoku japan, 2011. An earthquake is the vibration of earth produced by the rapid release of energy. Seismology and earths interior body waves can travel deep. Earthquakes and earths interior objectives explain the connection between earthquakes and plate tectonics. 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. Hence, this becomes yet another source of information about the interior. Earthquake waves transmitted through the earth are of two types.
Faults are fractures in earth where movement has occurred. For more information on how to use these and other tools, see appendix a. Define and describe the composition of earths crust, mantle and core. Exogenic as well as endogenic processes are constantly shaping the landscape. Use your map to answer the questions on the back of the worksheet. Chapter 8 earthquakes and earths interior summary 8. We know, with sufficient accuracy for most purposes, its size and shape. The epicenter is the point on earths surface directly above the focus. An earthquake generates body waves that spread out in all directions, like light.
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