Eartquake report


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This report contains the brief introduction to earthquake,its effect,causes etc..
And case study of kuchha(bhuj),Gujarat Earthquake on 26th january,2001

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Eartquake report

  1. 1. Seminar Report titled EARTHQUAKE Submitted BY Ghanva Krishna Guide(s) Prof. Ankita Parmar Prof. Sapan Parekh SCET, Surat September, 2013-14 Department of Computer Engineering
  2. 2. SARVAJANIK COLLEGE OF ENGINEERING AND TECHNOLOGY, SURAT Abstract Earthquakes occur as a result of global plate motion. However, this simple picture is far from complete. Some plate boundaries glide past each other smoothly, while others are punctuated by catastrophic failures. Some earthquakes stop after only a few hundred metres while others continue rupturing for a thousand kilometres. Earthquakes are sometimes triggered by other large earthquakes thousands of kilometres away. We address these questions by dissecting the observable phenomena and separating out the quantifiable features for comparison across events. We begin with a discussion of stress in the crust followed by an overview of earthquake phenomenology, focusing on the parameters that are readily measured by current seismic techniques. We briefly discuss how these parameters are related to the amplitude and frequencies of the elastic waves measured by seismometers as well as direct geodetic measurements of the Earth's deformation. We then review the major processes thought to be active during the rupture and discuss their relation to the observable parameters. We then take a longer range view by discussing how earthquakes interact as a complex system. Finally, we combine subjects to approach the key issue of earthquake initiation. This concluding discussion will require using the processes introduced in the study of rupture as well as some novel mechanisms. As our observational database improves, our computational ability accelerates and our laboratories become ii
  3. 3. more refined, the next few decades promise to bring more insights on earthquakes and perhaps some answers. Table of Contents 1.0 Introduction……………………………................ ................................ 1 1.1 Earthquake 1.2 Terms Related To Earthquake 2.0 Cause Of Earthquake……………………………………… …………..7 2.1 Faults 2.2 Surface Cause 2.3 Tectonic Cause 2.4 Volcanic Cause 3.0 Types Of Waves………………………………………. ……………....11 3.1 Body Waves 3.1.1 Primary (P) Waves 3.1.2 Secondary (S) Waves iii
  4. 4. 3.2 Surface waves 3.2.1 Love Waves 3.2.2 Rayleigh Waves 4.0 Strength Of Earthquake………………………. …………..…………14 4.1 Seismometers 5.0 Types Of Zones……………………………………………… ………..16 6.0 Earthquake Prediction………………………………………… …….18 7.0 Effect Of Earthquake……………………………………… …………19 8.0 Earthquake Safety Rules………………………………………….. ….23 9.0 Case Study (Earthquake of Bharuch,Gujrat2001)……..………….25 iv
  5. 5. 1.Introduction Earthquakes constitute one of the worst natural hazards which often turn into disaster causing widespread destruction and loss to human life. The effects of earthquake vary upon the magnitude and intensity. Earthquakes occur every now and then all round the world, except in some places where earthquakes occur rarely. The devastation of cities and towns is one of the effects of earthquake. An earthquake is a trembling or a shaking movement of the ground, caused by the slippage or rupture of a fault within the Earth's crust. A sudden slippage or rupture along a fault line results in an abrupt release of elastic energy stored in rocks that are subjected to great strain. This energy can be built up and stored over a long time and then released in seconds or minutes. Strain on the rocks results in more elastic energy being stored which leads to far greater possibility of an earthquake event. The sudden release of energy during an earthquake causes lowfrequency sound waves called seismic waves to propagate through the Earth's crust or along its surface. 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. In California there are two plates the Pacific Plate and the North American Plate. The Pacific Plate consists of most of the Pacific Ocean floor and the California Coast line. The North American Plate comprises most the North American Continent and parts of the Atlantic Ocean floor. These primary boundary between these v
  6. 6. two plates is the San Andreas Fault. The San Andreas Fault is more than 650 miles long and extends to depths of at least 10 miles. Many other smaller faults like the Hayward (Northern California) and the San Jacinto (Southern California) branch from and join the San Andreas Fault Zone. The Pacific Plate grinds northwestward past the North American Plate at a rate of about two inches per year. Parts of the San Andreas Fault system adapt to this movement by constant "creep" resulting in many tiny shocks and a few moderate earth tremors. In other areas where creep is NOT constant, strain can build up for hundreds of years, producing great EQs when it finally releases. Fig 1.1 Dam destroyed by an earthquake 1.1 What is Earthquake? “An Earthquake is the result of a sudden release of energy in the earth’s crust that creates seismic waves.” The seismic activity of an area refers to the frequency,type and size of earthquakes experienced over a period of time. For example: vi
  7. 7. If you throw stone in a pond of still water,series of waves are produced on the surface of water,these waves spread out in all directions from the point where the stone strikes the water. similarly, any sudden disurbances in the earth’s crust may produce vibration in the crust which travel in all direction from point of disturbances. 1.2Terms Related To Earthquake Crust: the top layer of the earth, which consists of solid rock. Both the continental crust (land masses) and oceanic crust (the land beneath the ocean) belong to the crust. Hypocentre or Focus: It is the point within the earth, from where seismic waves originate.It is the point on the fault where rupture(breaking of rocks) occurs and the location from which seismic waves are released. Epicenter: It is the point on the surface of the earth, vertically above the place of origin (hypocenter) of an earthquake. This point is expressed by its geographical Coordinates in terms of latitude and longitude. vii
  8. 8. Focal depth: It is the vertical distance between the Hypocentre (Focus) and Epicentre. Fault Line: A Fault line is the surface trace of a fault, the line of intersection between the earth’s surface. Fault plane:Fault plane are the crackes or sudden slips of the land . Fault Scrap: A Fault scrap is the topographic expression of faulting attributed to the displacement of the land surface by movement along faults. Richter Scale: An objective measure of the strength of an earthquake. It measures the degree of magnitude. Seismic Waves: vibrations that move through the earth in a way similar to waves moving in water. They can travel through solids and liquids. 2.Causes Of Earthquake The primary cause of an earthquake is faults on the crust of the earth. 2.1 Fault: “A fault is a break or fracture between two blocks of rocks in response to stress.” There is a chicken and egg relationship between faults and earthquakes viii
  9. 9. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake - or may occur slowly, in the form of creep. Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated displacements over geologic time. During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. The fault surface can be horizontal or vertical or some arbitrary angle in between. Earth scientists use the angle of the fault with respect to the surface (known as the dip) and the direction of slip along the fault to classify faults. Faults which move along the direction of the dip plane are dip-slip faults and described as either normal or reverse, depending on their motion. Faults that move horizontally are known as strike-slip faults and are classified as either rightlateral or left-lateral. Faults, which show both dip-slip and strike-slip motion are known as oblique-slip faults. ix
  10. 10. 1. Normal fault: a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems. 2. Thrust (reverse)fault: a dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. This type of faulting is common in areas of compression, such as regions where one plate is being sub ducted under another as in Japan. When the dip angle is shallow, a reverse fault is often described as a thrust fault. 3. Strike-slip fault: a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault. • A left-lateral strike-slip fault is one on which the displacement of the far block is to the left when viewed from either side. • A right-lateral strike-slip fault is one on which the displacement of the far block is to the right when viewed from either side. x
  11. 11. Some major causes of earthquakes on basic of its causes are: 1.Surface cause 2.Tectonic cause 3.volcanic cause 2.2 Surface Cause Great explosions, landslides, slips on steep coasts,dashing of sea waves, avalanches , railway trains, heavy trucks, some large engineering projects cause minor tremors.some of them are man made,other are natural. 2.3 Tectonic Cause Structural disturbances resulting in the parts of the lithosphere is the main cause of this type of earthquake. Most of the disastrous earthquakes belong to this category and occur in areas of great faults and fractures. Sudden yielding to strain produced on the rocks of accumulating stress causes displacements especially along old fault zones known as great transform faults. 2.4 Volcanic Cause xi
  12. 12. Earthquakes related to volcanic activity may produce hazards which include ground cracks, ground deformation, and damage to manmade structures. There are two general categories of earthquakes that can occur at a volcano: • volcano-tectonic earthquakes • long period earthquakes. Volcano-tectonic earthquakes: Earthquakes produced by stress changes in solid rock due to the injection or withdrawal of magma (molton rock). These earthquakes can cause land to subside and can produce large ground cracks. These earthquakes can occur as rock is moving to fill in spaces where magma is no longer present. Volcano-tectonic earthquakes don't indicate that the volcano will be erupting but can occur at anytime. Long period earthquakes: It is produced by the injection of magma into surrounding rock. These earthquakes are a result of pressure changes during the unsteady transport of the magma. When magma injection is sustained a lot of earthquakes are produced (Chouet, 1993). This type of activity indicates that a volcano is about to erupt. Scientists use seismographs to record the signal from these earthquakes. This signal is known as volcanic tremor. xii
  13. 13. 3.Types Of Waves Seismic waves produced due to earthquake are basically divided into two major types: • Body waves • Surface waves xiii
  14. 14. 3.1 Body waves: Two types of body wave are there: 3.1.1 Primary (P) Wave: • The faster of these body waves is called the primary or P wave. • Its motion is the same as that of a sound wave in that, as it spreads out, it alternately pushes (compresses) and pulls (dilates) the rock. • These P waves are able to travel through both solid rock, such as granite mountains, and liquid material, such as volcanic magma or the water of the oceans. 3.1.2 Secondary (S) Wave: • The slower wave through the body of rock is called the secondary or S wave. • As an S wave propagates, it shears the rock sideways at right angles to the direction of travel. • If a liquid is sheared sideways or twisted, it will not spring back. xiv
  15. 15. • S waves cannot propagate in the liquid parts of the earth, such as oceans and lakes. 3.2 Surface Wave: Surface waves travels parallel to the earth’s surface and these waves are slowest and most damaging. Surface wave are divided into following types: 3.2.1 Love waves: • Its motion is essentially that of S waves that have no vertical displacement. • it moves the ground from side to side in a horizontal plane but at right angles to the direction of propagation. • The horizontal shaking of Love waves is particuly damaging to the foundations of structures. • Love waves generally travel faster than Rayleigh waves. • Love waves (do not propagate through water) can effect surface water only insofar as the sides of lakes and ocean bays pushing water sideways like the sides of a vibrating tank. xv
  16. 16. 3.2.2 Rayleigh waves: • It’s Like rolling ocean waves. • Rayleigh waves wave move both vertically and horizontally in a vertical plane pointed in the direction in which the waves are travelling. • Rayleigh waves, becasuse of their vertical component of their motion can affect the bodies of water such as lakes. 4.Strength Of Earthquake Earthquake intensity varies. Some are so minor that they can only be felt at the epicenter. Other earthquakes are so strong that it shakes hundreds of thousands of square miles. xvi
  17. 17. Scientists measure the strength of earthquakes using machines known as seismographs, which record the trembling of the ground. This instrument is simply a pen that traces a straight line on a turning drum. When the earth moves, the pen is jolted out of its normal course, and traces a wiggle on the paper beneath it. A very sensitive seismograph can magnify the tiniest tremors one million times. The stronger the earth’s movement, the larger the wiggle is drawn. Using the information from the seismograph, scientists determine its strength using a magnitude scale known as the Richter Scale. The official definition of the magnitude of an earthquake is: “the logarithm to base ten of the maximum seismicwave amplitude (in thousandths of a millimeter) recorded on a standard seismograph at a distance of 100 kilometers from the earthquake epicenter.” Amount of energy released during different Earthquake: Intensity Of Earthquake On Richter Scale: 1.0 2.0 3.0 4.0 5.0 6.0 7.0 7.5 8.0 Energy Release (Amount Of TNT): 170 Grams 6 Kilogram 179 Kilogram 5 Metric Tons 179 Metric Tons 5643 Metric Tons 179100 Metric Tons 1 Mega Tons 564300 Metric Tons 4.1 Seismometers-The measurement of earthquake xvii
  18. 18. • Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and otherseismic sources. • Seismometers may be deployed at Earth's surface, in shallow vaults, in boreholes, or underwater. • A complete instrument package that records seismic signals is called a seismograph. Networks of seismographs continuously record ground motions around the world to facilitate the monitoring and analysis of global earthquakes and other seismic sources. Rapid location makes tsunami warnings possible of earthquakes because seismic waves travel considerably faster than tsunami waves. • Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth. xviii
  19. 19. 5.Types Of Zones The Geological Survey of India (G. S. I.) first published the seismic zoning map of the country in the year 1935. With numerous modifications made afterwards, this map was initially based on the amount of damage suffered by the different regions of India.because of earthquakes. Color coded in different shades of the color red, this map shows the four distinct seismic zones of India. Following are the varied seismic zones of the nation, which are prominently shown in the map: xix
  20. 20. • Zone – II This is said to be the least active seismic zone. This region is liable to MSK VI or less and is classified as the Low Damage Risk Zone. • Zone - III: This zone is classified as Moderate Damage Risk Zone which is liable to MSK VII. and also 7.8 The IS code assigns zone factor of 0.16 for Zone 3.The Andaman and Nicobar Islands, parts of Kashmir, Western Himalayas fall under this zone. • Zone - IV: This zone is called the High Damage Risk Zone and covers areas liable to MSK VIII. The IS code assigns zone factor of 0.24 for Zone 4. The IndoGangetic basin and the capital of the country (Delhi), Jammu and Kashmir fall in Zone 4. In Maharashtra the Patan area (Koyananager) is also in zone 4. • Zone - V: Zone 5 covers the areas with the highest risks zone that suffers earthquakes of intensity MSK IX or greater. The IS code assigns zone factor of 0.36 for Zone 5. It is referred to as the Very High Damage Risk Zone. The state of Kashmir,the western and central Himalayas, the North-East Indian region and Kutch fall in this zone. xx the Rann of
  21. 21. 6.Earthquake Prediction Earthquake prediction is usually defined as the specification of the time , location , and magnitude of a future earthquake within stated limits. But some evidence of upcoming Earthquake are following: • Unusual animal behavior • Water level in wells • Large scale of fluctuation of oil flow from oil wells • Foreshocks or minor shocks before major earthquake • Temperature change • Uplifting of earth surface • Change in seismic wave velocity xxi
  22. 22. 7.Effect Of Earthquake Most earthquake-related deaths are caused by the collapse of structures and the construction practices play a tremendous role in the death toll of an earthquake.Some primary effect of earth quack are following: • Loss of life and property • Damage to transport system i.e. roads, railways, highways, airports, marine • Damage to human infrastructure. • Communications such as telephone wires are damaged. • Water pipes, sewers are disrupted • Economic activities like agriculture, industry, trade and transport are severely affected. Secondary effects are the after-effects of the earthquake, such as fires, tidal waves, landslides and disease,lend slides,tsunami etc. • Landslides xxii
  23. 23. The shocks produced by earthquakes particularly in hilly areas and mountains which are tectonically sensitive causes landslides and debris fall on human settlements and transport system on the lower slope segments, inflicting damage to them. Occasionally large landslides can be triggered by earthquakes. In 1970 an earthquake off the coast of Peru produced a landslide than began 80 miles away from the earthquake. The slide was large (it's height at about 30 meters or 100 feet), traveled at more than 100 miles per hour and plowed through part of one village and annihilated another, killing more than 18,000 people. • Shaking and ground rapture 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. Ground rupture is a visible breaking and displacement of the Earth's surface along the trace of the fault, which may be of the order of several metres in the case of major earthquakes. Ground rupture is a major xxiii
  24. 24. risk for large engineering structures such as dams, bridges and nuclear power stations. • Fires The strong vibrations caused by severe earthquakes strongly shake the buildings and thus causing severe fires in houses, mines and factories because of overturning of cooking gas, contact of live electric wires, churning of blast furnaces, displacement of other fire related and electric appliances. • Soil liquefaction Soil liquefaction occurs when, because of the shaking, water-saturated granular material (such as sand) temporarily loses its strength and transforms from xxiv
  25. 25. a solid to a liquid. Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits. For example, in the 1964 Alaska earthquake, soil liquefaction caused many buildings to sink into the ground, eventually collapsing upon themselves. • Tsunami The seismic waves caused by earthquake( measuring more than 7 on richter scale) travelling through sea water generate high sea waves and cause great loss of life and property.fig shows the tsunami of the 2004 Indian ocen earthquake. xxv
  26. 26. • Floods A flood is an overflow of any amount of water that reaches land. Floods occur usually when the volume of water within a body of water, such as a river or lake, exceeds the total capacity of the formation, and as a result some of the water flows or sits outside of the normal perimeter of the body. However, floods may be secondary effects of earthquakes, if dams are damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods. xxvi
  27. 27. 1 8. Earthquake Safety Rules  Before an earthquake • Ensure that water heaters and gas appliances are firmly fixed and shut off when not in use, as they can cause fire hazards during an earthquake. • Conduct occasional home earthquake drills so that your family has the knowledge to avoid unnecessary injuries and panic in the event of an earthquake. • Evacuate old damaged buildings as they are sure to down first during the earthquake. xxvii
  28. 28. • Be aware to tackle situations of earthquake while at home, driving a car or in a public place. If you are in house; • Don’t use lift for getting down from building. • Be prepared to move with your family. If you are in shop ,school or office; • Don’t run for an exit. • Take cover under a disk/table. • Move away from window glass. • Do not go near electric point and cable. Keep away from weak portion of the building and false ceiling.  After the Earthquake • Keep calm, switch on the transistor radio and obey instructions. • Keep away from beaches and low banks of river. A huge wave may sweep in. • Do not re enter badly damaged buildings and do not go near damage structures. • Turn off the water, gas and electricity. • Do not smoke, light match or use a cigarette lighter. • Do not turn on switches there may be gas leak or short circuit xxviii
  29. 29. • If there is any fire, try to put it out or call fire brigade. • Do not drink water from open containers without having examined it. • If you aware of people have been buried, tell the rescue team. Do not rush and try not to worsen the situation. • Avoid places where there are loose electric wires and do not come in contact with any metal object. • Eat something. You will better and more capable of helping other. • Do not walk around the streets to see what is happening. Keep the streets clear so rescue vehicles can access the roads easily. Some major Earthquake of india: Date Place Scale Damage Sept 2, 1993 Latur (maharashtra) 6.3 Large areas of Maharashtra rocked. 10,000 people lost lives. May 22, 1997 Jabalpur (Maharashtra) 6.0 40 person killed and over 100 injured. March 29, 1999 Nandprayag 6.8 widespread destruction in chamoli , rudraprayag and other areas. Massive loss of human life. Jan. 26, 2001 Bhuj (gujrat) 7.8 Tremors left by India and its neighboring countries. Over 1 lakh people killed. Huge loss to property and infrastructure. Oct. 8, 2005 Muzzaffarabad in Pakistan occupied Kashmir 7.4 Heavy damage to life and property. Death toll about one lakh in Pakistan and nearly 2000 in India. xxix
  30. 30. 9.Casestudy Earthquake Case study: Bhuj Earthquake 26th January 2001 A Powerful Earthquake of magnitude 6.9 on Richter-Scale rocked the Western Indian State of Gujarat on the 26th of January, 2001. It caused extensive damage to life & property. This earthquake was so devastating in its scale and suffering that the likes of it had not been experienced in past 50 years. Leaving thousands seriously injured, bruised and handicapped; both physically, psychologically and economically. The epicenter of the quake was located at 23.6 north Latitude and 69.8 east Longitude, about 20 km Northeast of Bhuj Town of the Kutch district in Western Gujarat. At a depth of only 23 kms below surface this quake generated intense shaking which was felt in 70% region of India and far beyond in neighbouring Pakistan and Nepal too. This was followed by intense after shocks that became a continued source of anxiety for the populace. The Seismicity of the affected Area of Kutch is a known fact with a high incidence of earthquakes in recent times and in historical past. It falls in Seismic Zone V. The only such zone outside the Himalayan Seismic Belt. In last 200 years important damaging earthquakes occurred in 1819, 1844, 1845, 1856, 1869,1956 in the same vicinity as 2001 earthquake. Twenty-one xxx
  31. 31. of the total 25 districts of the state was affected in this quake. Around 18 towns, 182 talukas and 7904 villages in the affected districts have seen large-scale devastation. The affected areas even spread up to 300 km from the epicentre. In the Kutch District, four major urban areas – Bhuj, Anjar, Bachau and Rapar suffered near total destruction. The rural areas in the region are also very badly affected with over 450 villages almost totally destroyed. In addition, wide spread damages also occurred in Rajkot, Jamnagar, Surendranagar, Patan and Ahmedabad districts. Other Urban areas such as Ganhidham, Morvi, Rajkot and Jamnagar have also suffered damage to major structures, infrastructure and industrial facilities. Ahmedabad the capital was also severely affected. Bhuj Earthquake: • Date: 26 January 2001 • Origin line: 08 hrs.46 min. 42.9 sec. IST • Epicenter: Latitude 23.40° N Longitude 70.28°E • Magnitude: 7.7 • Focal Depth: 25 kms. On the morning of January 26, 2001, the Nation’s 52nd Republic Day, a devastating earthquake occurred in the xxxi
  32. 32. Kutchh district of the state of Gujarat. The earthquake was felt as far away as Delhi in the north, Kolkata in the east. Bhuj town and the village Bhachau, 60 km east of Bhuj, were the worst affected and many other areas of Gujarat including its state headquarters Ahmedabad, were badly affected. Damage assessment : • There were more than 20,000 deaths and 167,000 people injured Four districts of Gujarat lay in ruin and altogether, 21 districts were affected. • Around 300,000 families and at least 3 million children aged 14 and under were affected. • Around 600,000 people were left homeless. • In the city of Bhuj, more than 3,000 inhabitants of the city lost their lives; the main hospital was crushed and close to 90% of the buildings was destroyed. • There was significant damage to infrastructure with facilities such as hospitals, schools, electric power and water systems, bridges and roads damaged or destroyed. xxxii
  33. 33. Fig (a): Damage to high rise building in Bhuj cx c Fig (b): 5 year old girl recovers at a hospital in Bhuj on Monday after Friday's massive earthquake. ccvvvv xxxiii