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  1. 1. Disaster Assessment EARTHQUAKE By: Dalpat Prajapati
  2. 2. Earthquake
  3. 3. What is EARTHQUAKE? • Earthquake refers to the result of a sudden release of energy in the Earth's crust that creates seismic waves. It may also refer to sudden and violent shaking of the ground, sometimes causing great destruction.
  4. 4. What CAUSES Earthquakes? • An earthquake is caused by a sudden slip on a fault. Stresses in the earth's outer layer push the sides of the fault together. Stress builds up and the rocks slips suddenly, releasing energy in waves that travel through the earth's crust and cause the shaking that we feel during an earthquake. An EQ occurs when plates grind and scrape against each other.
  5. 5. Types Of FAULT Strike-slip Thrust Normal The form of faulting depends upon the type of plate motion and nature of rocks.
  6. 6. STRIKE SLIP Fault Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. If the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral.
  7. 7. THRUST Fault A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lowerstratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger. Thrust faults are the result of compressional forces.
  8. 8. NORMAL Fault A fault in which the hanging wall has moved downward relative to the footwall.
  9. 9. Earthquake Terms
  10. 10. Where do earthquakes occur? Is it random? Is any place safe or free of earthquakes?
  11. 11. SHALLOW-FOCUS DEEP-FOCUS earthquakes
  14. 14. EARTHQUAKE SWARMS Earthquake swarms are sequences of earthquakes striking in a specific area within a short period of time. They are different from earthquakes followed by a series of aftershocks by the fact that no single earthquake in the sequence is obviously the main shock, therefore none have notable higher magnitudes than the other.
  15. 15. When an earthquake occurs, the energy is dissipated into the surrounding medium through seismic waves.
  16. 16. SEISMIC WAVES Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.
  17. 17. Type of Seismic waves • There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are Body waves and Surface waves. • Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.
  18. 18. BODY WAVES P-waves; also known as primary waves or pressure waves S-waves; also referred to as secondary or shear waves P- waves S- waves
  19. 19. SURFACE WAVES • Love and Raleigh waves Love waves Raleigh waves
  20. 20. HOW IS EARTHQUAKE INTENSITY MEASURED? There are currently two “measuring” schemes used to “quantify” or “qualify” the destructiveness or power of an earthquake. 1) The Mercalli Intensity scale (it is qualitatively based) 2) The Richter Magnitude scale (it is quantitatively based)
  21. 21. HOW COMMON ARE EARTHQUAKES? Magnitude (Richter Scale) Number per Year 0 – 3.4 >800,000 4.9 – 5.4 1400 5.5 – 6.1 500 7.0 – 7.3 15 >8 1 every 10 years
  24. 24. Shaking and Ground Rupture • Shaking and ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings and other rigid structures. • The severity of the local effects depends on the complex combination of the earthquake magnitude, the distance from the epicenter, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation. The ground-shaking is measured by ground acceleration.
  25. 25. Landslides and Avalanches • Earthquakes, along with severe storms, volcanic activity, coastal wave attack, and wildfires, can produce slope instability leading to landslides, a major geological hazard. Landslide danger may persist while emergency personnel are attempting rescue.
  26. 26. Fires • Earthquakes can cause fires by damaging electrical power or gas lines. In the event of water mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a fire once it has started. For example, more deaths in the 1906 San Francisco earthquake were caused by fire than by the earthquake itself.
  27. 27. Soil Liquefaction • Soil liquefaction occurs when, because of the shaking water-saturated granular material (such as sand) temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits.
  28. 28. Tsunami • Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes. • Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them. • Ordinarily, subduction earthquakes under magnitude 7.5 on the Richter scale do not cause tsunamis, although some instances of this have been recorded. Most destructive tsunamis are caused by earthquakes of magnitude 7.5 or more.
  29. 29. Flood • Earthquakes may cause landslips to dam rivers, which collapse and cause floods. • The terrain below the Sarez Lake in Tajikistan is in danger of catastrophic flood if the landslide dam formed by the earthquake, known as the Usoi Dam, were to fail during a future earthquake. Impact projections suggest the flood could affect roughly 5 million people.
  30. 30. Human Impacts • An earthquake may cause injury and loss of life, road and bridge damage, general property damage (which may or may not be covered by earthquake insurance), and collapse or destabilization (potentially leading to future collapse) of buildings. The aftermath may bring disease, lack of basic necessities, and higher insurance premiums.
  31. 31. PREDICTION
  32. 32. Prediction • Many methods have been developed for predicting the time and place in which earthquakes will occur. Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific day or month. However, for well-understood faults the probability that a segment may rupture during the next few decades can be estimated. • Earthquake warning systems have been developed that can provide regional notification of an earthquake in progress, but before the ground surface has begun to move, potentially allowing people within the system's range to seek shelter before the earthquake's impact is felt.
  33. 33. PREVENTION
  34. 34. Preparing for an Earthquake 1. Become familiar with earthquake terms. Aftershocks Epicenter Fault Focus Intensity Magnitude Mercalli Scale Tidal wave Tsunami
  35. 35. Preparing for an Earthquake 2. Safeguard your home by: • Bolting bookshelves, water heaters and cabinets to wall studs. • Anchoring things so that they will not move or fall during an earthquake is the most important thing you can do to make yourself safe. Keeping things in place also means they will not break.
  36. 36. During Earthquake 1. Get under a heavy table or desk and hold on, or sit or stand against an inside wall. 2. Keep away from windows. 3. If indoors, stay indoors. 4. If outdoors, stay outdoors away from falling debris, trees and power lines. 5. If in a car, stay in the car. 6. Many injuries occur when people act on their impulse to run. 7. Train yourself to take cover where you are.
  37. 37. Responses Inside Buildings during an Earthquake 1. Drop, cover, and hold on. 2. Get under a table. 3. If there are no tables, get under or down between rows of chairs or against inner walls. 4. Do not stand in a doorway. Buildings today have so much partitioning, much of which is temporary, that many doorways are actually weak points. Doorways are not a good solution in a group situation either. 5. If you have nothing to get under, sit down against an interior wall or next to a chair, holding on if possible. 6. If you are in bed, it's best to stay there, hold on, and pull the pillows over your head for protection. 7. If children are in another room, take cover in the closest safe place and call to them to do the same.
  38. 38. Responses If You Are Outside during an Earthquake 1. Outside, get away from buildings, walls, trees and power lines. 1. If you cannot get clear of hazards, getting back inside a building is better than staying on the sidewalk. 2. Sidewalks next to buildings are among the worst places to be. 2. In a car, ease off the accelerator and slow down carefully. Do not stop on or under overpasses and bridges if you can avoid them. Be aware of what traffic around you is doing and act accordingly. 3. If you live in coastal areas, be aware of possible tsunamis.
  39. 39. After Earthquake 1. Take basic precautions immediately after an earthquake. In addition to those outlined in the General Family Preparedness, Residential Fires and Hazardous Materials Accidents sections you should: 2. Expect aftershocks. 3. Avoid using vehicles except in emergencies. 4. Check yourself for injuries and protect yourself by putting on shoes, work gloves and any other protective gear at hand. 5. If the electricity is off, turn on a flashlight.
  40. 40. After Earthquake 6. Once you are sure that you're all right, check the people around you for injuries. 1. You might ask loudly, "Is everyone okay?" This will also help calm people. 2. The types of injuries that happen most often in an earthquake include cuts, bruises, fractures and physiological shock. 7. Check the entire building for structural damage and chemical spills. Refer to the section on Hazardous Materials Accidents for further response information. 8. Check chimneys for cracks and damage. The initial check should be made from a distance. Have a professional inspect the chimney for internal damage that could lead to fire.
  41. 41. CASE STUDY
  42. 42. 26th January, 2001 Bhuj, Gujarat. Scale between 7.6 and 7.7
  43. 43. The 2001 Gujarat earthquake occurred on January 26, 2001, India's 52nd Republic Day, at 08:46 AM local time (3:16 UTC) and lasted for over two minutes. The epicentre was about 9 km south-southwest of the village of Chobari in Bhachau Taluka of Kutch District of Gujarat, India. The earthquake reached a magnitude of between 7.6 and 7.7 on the moment magnitude Scale and had a maximum felt intensity of X (Intense) on theMercalli intensity scale. The quake killed around 20,000 people (including 18 in South eastern Pakistan), injured another 167,000 and destroyed nearly 400,000 homes.
  44. 44. Five Major Earthquakes in India 1. 2. 3. 4. 5. 2001, Gujarat 1934, Bihar 1993, Maharashtra 1950, Assam 1991, Uttarkashi | 7.7 Richter Scale | 12,300 Deaths | 8.1 Richter Scale | 10,500 Deaths | 6.4 Richter Scale | 15,854 Deaths | 8.6 Richter Scale | 1,526 Deaths | 6.1 Richter Scale | 3210 Deaths
  46. 46. 22 May, 1960 Valdivia, Chile. R. Scale 9.5 1655 People Deaths 1
  47. 47. 2 28 March, 1964 Prince William Sound, Alaska R. Scale 9.2 1400 People Deaths
  48. 48. 3 26 December, 2004 Sumatra, Indonesia R. Scale 9.1 227,900 People Deaths
  49. 49. 4 11 March, 2011 Sendai, Japan R. Scale 9.0 15,883 People Deaths
  50. 50. 5 04 November , 1952 Kamchatka, Russia R. Scale 9.0
  51. 51. 6 27 February, 2010 Bio-bio, Chile R. Scale 8.8 800,000 People Deaths
  52. 52. 7 31 January, 1906 The coast of Ecuador R. Scale 8.8 1505 People Deaths
  53. 53. 8 02 April, 1965 Rat Islands, Alaska R. Scale 8.7
  54. 54. 9 28 March 2005 Sumatra, Indonesia R. Scale 8.6 1313 People Deaths
  55. 55. 10 15 August 1950 Assam - Tibet R. Scale 8.6 780 People Deaths
  56. 56. THANK YOU