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  1. 1. EARTHQUAKES Prepared by Abdelrahman Ismail Hassan
  2. 2. Table of Contents:                   Introduction to Earthquakes: (1.1-1.4) (1-1) : History of Earthquakes. (1-2) :What is the Earthquakes. (1-3): What is the Seismic Waves and it’s types. (1-4) :Epicenter location Earthquake Causes (2.0) Earthquake classification Scale (3.1-3.2) (3-1) Predictions (3-2) Scales ,Measuring, and forecasting (Richter & Mercalli scale) Earthquake Locations (4.1-4.3) (4-1) Locations (4-2) 10 Most Destructive Earthquakes (4-3) Earthquakes in Egypt Types of earthquakes.(5.0) Effects of Earthquakes.(6.1-6.2) (6-1) Effects of Earthquakes (6-2) The Great Sumatra-Andaman Earthquake/Tsunami Conclusion .
  3. 3. (1-1) History of Earthquakes. • Earthquakes have been recorded as early as 1177 B.C. in China. Of course earthquakes have been a part of myth and legend since the dawn of man. • In Greek Mythology, Poseidon was "God of the Sea". Yet one of his powers was thought to be the reason of Earthquakes. Introduction to Earthquakes
  4. 4. • Aristotle was one of the first Europeans to create a theory about the origin of Earthquakes. He thought that they were the result of heavy winds • Not much more study was concentrated on earthquakes until the mid-1700s. Introduction to Earthquakes
  5. 5. • Soon scientists from several countries were exchanging observations and theories on earthquakes. • In the 1850s Robert Mallet, figured out a means to measure the velocity of seismic waves. Meanwhile, in Italy, Luigi Palmieri invented an electromagnetic seismograph that was the first seismic instruments capable of detecting earthquakes imperceptible to human beings. Introduction to Earthquakes
  6. 6. • It was about 1910 that Alfred Wegener published his theory of plate tectonics to explain volcanic and seismic activity. • Since then, seismologists have continued to work at a furious pace, building better instruments, computer models, theories and forecast to study the causes and effects of earthquakes. Introduction to Earthquakes
  7. 7. (1.2)What is the Earthquake : • What is the Earthquake ? • It is the vibration of the ground due to the sudden release of energy by the breaking and shifting of rock beneath the Earth´s surface and it creates seismic waves. • The Earths crust near tectonic plate edges are forced to bend, compress, and stretch due to the internal forces within the earth, causing earthquakes. Introduction to Earthquakes
  8. 8. • (1-3)What is the Seismic Waves: Seismic waves are generated by the release of energy during an earthquake. They travel through the earth like waves travel through water. • Focus (Hypocenter): spot underground where the rock begins to break. • Most foci are located within 65 km of the Earths surface, however, some have been recorded at depths of 700 km. Introduction to Earthquakes
  9. 9. • Epicenter: The location on the Earths surface directly above the focus. • Aftershock: tremors that occur as rocks adjust to their new position. Introduction to Earthquakes
  10. 10.  Two types of seismic waves are generated at the earthquake focus: 1. Body waves: spread outward from the focus in all directions. 2. Surface waves spread outward from the epicenter to the Earth’s surface These waves can move rock particles in a rolling motion that very few structures can withstand. These waves move slower than body waves Introduction to Earthquakes
  11. 11. Body waves: 1. Primary Wave (P wave): • Compressional wave (travels in the same direction the waves move • Very fast (4-7 km/second) • Can pass through a fluid (gas or liquid) • Arrives at recording station first Introduction to Earthquakes
  12. 12. • 2. Secondary Wave (S wave): • Transverse wave (travels perpendicular to the wave movement • Slower moving (2-5 km/second) • Caused by a shearing motion • Cannot pass through a fluid (gas or liquid) Introduction to Earthquakes
  13. 13. • Surface waves: are produced when earthquake energy reaches the Earth's surface. Surface waves moves rock particles in a rolling and swaying motion, so that the earth moves in different directions. These are the slowest moving waves, but are the most destructive for structures on earth. 1. Love (L) wave: Rock moves from side to side like snake 2. Raleigh wave: Rolling pattern like ocean wave Introduction to Earthquakes
  14. 14. Introduction to Earthquakes
  15. 15. (1-4)Epicenter location: • Earthquake scientists, or seismologists, can locate the epicenter of an earthquake as long as the vibrations are felt at three different seismograph stations by: 1. Locate at least 3 stations on a map that recorded the seismic waves 2. Calculate the time difference between arrival of Pwaves and arrival of S-waves from a seismogram 3. The epicenter is where the circles intersect. Introduction to Earthquakes
  16. 16. Epicenter location using three stations McGraw Hill/ Glencoe, 1st ed., pg 170 Introduction to Earthquakes
  17. 17. (2.0) Causes of Earthquakes:
  18. 18. • How Earthquakes Happen? • Most earthquakes are caused indirectly by plate tectonics. • Plates move at 1-10 cm/year (about how fast your fingernails grow) and have moved vast distances in the Earth’s 4.6 billion year history. Earthquake Causes
  19. 19. Earthquake locations around the world and their correlation to plate boundaries. Plate boundaries are outlined by red circles, which indicate past earthquake epicenters. Earthquakes Causes
  20. 20. • There are approximately 7 major and 12 minor plates. The boundaries between plates often do not coincide with the boundaries between continents and oceans. • There are three types of boundaries between plates: • (1) convergent [plates coming together] • (2) divergent [plates separating] • (3) transform [plates sliding past one-another]. FEMA 159. Earthquakes. Produced by The National Science Teachers Association, 1992. Earthquake Causes
  21. 21. • Faults Plate movement or other forces can cause tremendous stress on the rocks that make up the earth’s outer shell. When rock is strained beyond its limit, it will fracture, and the rock mass on either side will move. This fracture is called a fault. Faults often are classified according to whether the direction of movement is predominantly horizontal or vertical FEMA 159. Earthquakes. Produced by The National Science Teachers Association, 1992.
  22. 22. • Intraplate Activity : Plate tectonics involves inter-plate, or “between-plate,” activity. Although this theory explains plate boundary earthquakes, it does not explain all seismic activity. Many large, devastating earthquakes occur within continents, away from plate edges. These earthquakes are caused by intra-plate activity. The 1811 and 1812 New Madrid fault earthquakes in the central United States are a good example of earthquakes caused by intra-plate activity. Earthquakes of this type probably result from more localized geological forces such as mid-plate compression
  23. 23. • Sudden Rupture • during an earthquake when a sudden rupture occurs along a fault. As the rupture travels through the rock, energy is released that creates the motions associated with an earthquake. • If a fault rupture is shallow enough, the fault line may appear on the earth’s surface. • Most rocks are brittle above 15-20 km depth and ductile below this depth. This boundary is called the brittle-ductile transition (BDT), and corresponds to a temperature of 300-450ºC.
  24. 24. • Most deep earthquakes (greater than BDT depth) occur at subduction zones in a zone called a Wadati-Benioff zone which extends to 670 km depth. • Deep earthquakes occur in the Wadati-Benioff zone for two reasons: 1. rocks remain cool, below the BDT temperature 2. sudden mineral changes induce zones of weakness that allow rocks to suddenly shift, producing earthquakes.
  25. 25. Earthquake classification scales (Forecasting &Measuring) (3.1) Predictions • Earthquakes can be felt over large areas although they usually last less than one minute. • Earthquakes cannot be predicted -- although scientists are working on it • It is thought that some animals may feel vibrations from a quake before humans, and that even minutes before a quake dogs may howl and birds fly erratically. • Most of the time, you will notice an earthquake by the gentle shaking of the ground. You may notice hanging plants swaying or objects wobbling on shelves. Earthquake classification scales
  26. 26. • Earthquakes can be very destructive at the Earths surface. The magnitude of an earthquake is a measure of how destructive it is. Basically the magnitude corresponds to how much energy is released. • Today, a standard magnitude scale is used, Seismic Moment, which more accurately represents the energy released in an earthquake, especially large magnitude events. • Thousands of earthquakes are recorded every day with magnitudes < 3.0 but are almost never felt. Earthquake classification scales
  27. 27. (3.2) Scales (Forecasting &Measuring)  Seismometer: instruments that detect seismic waves  seismogram is visual record of arrival time and magnitude of shaking associated with seismic wave  Seismograph: device that measures the magnitude of earthquake Earthquake classification scales
  28. 28.  Mercalli Intensity scale: measures the intensity of how people and structures are affected by the seismic event. In essence, it measures damage. It is much more subjective and uses numbers ranging from 1 (no damage) to 12 (total destruction). Earthquake classification scales
  29. 29.  Richter Scale- (logarithmic scale) • The Richter Scale is used to express earthquake magnitude on the basis of the height (amplitude) of the largest line (seismic wave, P or S) on a seismogram. • The Richter scale was originally developed for earthquakes in Southern California. The utility of this scale was its ability to account for decreased wave amplitude with increased distance from the epicenter. Earthquake classification scales
  30. 30. Complications of the Richter scale include: 1. The Richter scale originally only applied to shallow-focus earthquakes in southern California so now must be modified. 2. Magnitudes calculated from seismograms above 7 tend to be inaccurate. Earthquake classification scales
  31. 31. MERCALLI VS. RICHTER Earthquake classification scales
  32. 32. Earthquake Locations (4-1) Locations • No part of the Earth's surface is safe from earthquakes. But some areas experience them more frequently than. • Earthquakes are most common at plate boundaries, where different tectonic plates meet. The largest events usually happen where two plates are colliding - this is where large amounts of stress can build up rapidly. • Earthquake classification scales
  33. 33. Plate boundaries Earthquake Locations
  34. 34. • About 80 percent of all recorded earthquakes occur at the circum-Pacific seismic belt (also known as The Ring of Fire). The Ring of Fire Earthquake classification scales
  35. 35. • Intraplate earthquakes occur less commonly. They take place in the relatively stable interior of continents, away from plate boundaries. This type of earthquake generally originates at more shallow levels. 2 1 Intraplate earthquakes Earthquake classification scales 3
  36. 36. Earthquakes map world (USGS 2004-2010) Earthquake classification scales
  37. 37. (4-2) 10 Most Destructive Earthquakes Earthquake Locations
  38. 38. Earthquake classification scales
  39. 39. • (4-3) Earthquakes in Egypt : • The 1992 Cairo earthquake occurred on 12 October, near Dahshur, 35 km south of Cairo. The earthquake had a magnitude of 5.8, but was unusually destructive for its size. The earthquake was felt throughout most of northern Egypt, in Alexandria, Port Said and as far south as Asyut, and in southern Israel. • The Earthquake caused about 545 deaths, injuring 6,512 and making 50,000 people homeless. It was the most damaging seismic event to affect Cairo. Earthquake classification scales
  40. 40. • Many buildings and monuments were severely damaged or collapsed. Modern concrete skeletal structures suffered minor nonstructural damage. • Earthquake physical damage was estimated at about one billion U.S. Dollars. Earthquake Locations
  41. 41. • The 1995 Gulf of Aqaba earthquake (Nuweiba earthquake) occurred on November 22 and registered 7.3 on the moment magnitude scale. • The epicenter was located 60 kilometers south of the head of the Gulf of Aqaba where the countries of Egypt, Israel, Jordan, and Saudi Arabia converge. Earthquake Locations
  42. 42. • At least 8 people were killed and 30 were injured in the meizoseismal area. • Damage to buildings occurred in the coastal cities of Eastern Egypt. Earthquake Locations
  43. 43. (5.0)Types of earthquakes: There are three different types of earthquakes: tectonic, volcanic, and explosion. The type of earthquake depends on the region where it occurs and the geological make-up of that region. 1. Tectonic earthquakes: These occur when rocks in the Earth's crust break due to geological forces created by movement of tectonic plates. Types of earthquakes
  44. 44. 2. Volcanic earthquakes: occur in conjunction with volcanic activity. Types of earthquakes
  45. 45. 3. Explosion earthquakes result from the explosion of nuclear and chemical devices. Types of earthquakes
  46. 46. (6-1) Effects of Earthquakes 1. Ground Displacement Ground surface may shift during an earthquake (esp. if focus is shallow). Vertical displacements of surface produce fault scarps Landslides. 2. Liquefaction and Landslides: Results in a loss of soil strength & the ability of the soil to support weight Effects of earthquakes
  47. 47. 3. Fatalities(Death) Effects of earthquakes
  48. 48. 4. Fires: Fires often break out following earthquakes. Fires can easily get out of control since the earthquake. There are many demands made on the emergency response systems that slow down response to fires. Effects of earthquakes
  49. 49. 5. Shaking and Collapse of Building : Frequency of shaking differs for different seismic waves. High frequency body waves shake low buildings more. Low frequency surface waves shake high buildings more. Intensity of shaking also depends on type of subsurface material. Effects of earthquakes
  50. 50. 6. Seiches • The back & forth movement of water in a semi closed/closed body of water- could cause flooding more from submarine landslide. • In 1959, a 7.3 magnitude earthquake occurred in Montana. As a result of faulting near Hebgen Lake, the bedrock beneath the lake was permanently warped, causing the lake floor to drop and generate a seiche. Maximum subsidence was 6.7 meters in Hebgen Lake Basin. About 130 square kilometer subsided more than 3 meters, and about 500 square kilometers subsided more than 0.3 meters. Types of earthquakes
  51. 51. 7. Seismic Sea Waves Tsunami) : a series of huge waves that can cause major devastation and loss of life when they hit the coast. The word tsunami is a Japanese word which means 'harbor waves' (tsu - harbor, nami - waves). The possible causes of a tsunami are an underwater earthquake with the Richter scale magnitude of over 6.75, sub marine rock slides, volcanic eruptions or if an asteroid or a meteoroid crashes into the water from the space. Types of earthquakes
  52. 52. Types of earthquakes
  53. 53. • When such a large volume of water is moved, the resulting wave is very large and can be spread over an area of a hundred miles. This wave can travel from the point of origin to the coast at great speed. A tsunami has been known to travel with speeds as high as 600 mph in the open ocean. a tsunami can move from one end of the ocean to the other end in a few hours! Effects of earthquakes
  54. 54. Effects of earthquakes
  55. 55. • With the advance in technologies over the years, tsunamis can now be detected before they hit the coast thereby reducing loss of life. Fortunately, tsunamis are very rare with approximately six of them hitting the coast every century, most of them occurring in the Pacific Ocean. Effects of earthquakes
  56. 56. Tsunami damage in Hilo, Hawaii. Effects of earthquakes
  57. 57. Effects of earthquakes
  58. 58. (6-2) The Great Sumatra-Andaman Earthquake/Tsunami • Since 1945, more people have been killed by tsunamis than earthquakes. A tsunami event that occurred recently and received global news coverage was the catastrophic tsunami that was generated in the Indian Ocean on December 26, 2004. The epicenter of the earthquake that triggered the series of tsunami’s was located off the west coast of Sumatra, Indonesia. More than 225,000 people in 11 countries were killed. The waves were up to 100 feet high Effects of earthquakes
  59. 59. • The earthquake was the 2nd largest ever recorded on a seismograph at ~9.2 on the Richter scale and it cause the entire planet to vibrate up to 1 centimeter, causing smaller earthquakes in other parts of the world. • The tsunami took anywhere from 15 minutes to 7 hours to reach the various coastlines that were devastated. • In the minutes preceding the tsunami wave, the sea withdrew from the shores by nearly 2 miles, attracting people to the beach with fatal consequences. Effects of earthquakes
  60. 60. Types of earthquakes
  61. 61. • References: • Earthquake Causes and Characteristics • Fergany, E.A.; Sawda S. (2009). "Estimation of Ground Motion at Damaged Area During 1992 Cairo Earthquake Using Empirical Green's Function“ . • South Carolina Department of Education 2005. • Klinger, Yann; Rivera, Luis; Haessler, Henri; Maurin, JeanChristophe (August 1999) , "Active Faulting in the Gulf of Aqaba: New Knowledge from the Mw 7.3 Earthquake of 22 November 1995” • Mohamad,, Abdul, Gomez, Francisco; Muawia et al (2000), "Remote Earthquake Triggering along the Dead Sea Fault in Syria following the 1995 Gulf of Aqaba Earthquake.
  62. 62. • • •
  63. 63. Thank you