Earthquake Engineering 2012 Lecture 0103 Measures of Earthquakes

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  • 1. EARTHQUAKEENGINEERING1.3. Waves & Measures 1.3.1. Seismic Waves 1.3.2. Earthquake Measures
  • 2. 1.3.1. Seismic WavesDefinition "seismic waves seismic waves" are the vibrations resulting as a result  g of the energy released from the earthquake These waves travel outward from the source of the  earthquake along the surface and through the Earth at  earthquake along the surface and through the Earth at varying speeds depending on the material through  which they move. Prof. Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 3. 1.3.1. Seismic WavesClassification Body Waves Primary (P) Secondary (S) SV SH Surface Waves Love (LQ) Reliegh (LR) Successive (Torsion)Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 4. 1.3.1. Seismic WavesBody and Surface WavesDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 5. 1.3.1. Seismic WavesBody Waves (Primary Waves)The faster of the seismicwaves The P waves are able to travel through solid rock, liquid Its motion is the same as material, such as volcanic magma that of a sound wave in a or the water of the oceans. fluid In most earthquakes, the P waves are felt firstDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 6. 1.3.1. Seismic WavesBody Waves (Secondary Waves) The slower wave through the body of rock is called the secondary or S wave. At right angles to the direction of travel The S waves cannot propagate in the liquid parts of the earth, such as the oceans, and their amplitude is significantly reduced in liquefied soil.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 7. 1.3.1. Seismic WavesIllustration (Body & Surface Waves) Rayleigh Waves Love WavesDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 8. 1.3.1. Seismic WavesSurface Waves Love wave moves the ground side to side in a horizontal plane parallel to the earth’s surface Rayleigh a e Ra leigh wave like rolling ocean wave, the pieces of rock distributed by a Its It motion i restricted t ti is t i t d to Rayleigh wave move both near the ground surface. vertically and horizontally in a vertical planeDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 9. 1.3.1. Seismic WavesIllustration (Surface Waves) Love wave Rayleigh wave Rayleigh Waves Love WavesDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 10. 1.3.1. Seismic WavesPropagation of WavesDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 11. 1.3.1. Seismic WavesPropagation of WavesDr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 12. 1.3.1. Seismic Waves Earths Structure Earth Diameter about 12756 Km Crustal Earthquakes Up to 30 Km Shallow Earthquakes 5-20 Km Moderate E th M d t Earthquakes 20 50 K k 20-50 Km Deep Earthquakes 300-700Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 13. 1.3.1. Seismic WavesWave Recording g Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 14. 1.3.1. Seismic Waves Wave Velocity y Velocity of P wave Velocity of S wave K - Bulk Modulus - Soil Rigidity  - DensityProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 15. 1.3.1. Seismic WavesWave Velocity y P Waves 1-14 (8) S Waves 1-8 (4) Love W L Waves 2-6 Releigh Waves 1-5Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 16. 1.3.1. Seismic WavesFocal DistanceArrival Timesd- Focal DistanceCommon Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 17. 1.3.2. Earthquake Measures Magnitude Modified Mercally Scale (1 to 12 Points concerning Earthquake Effects Peak Ground Acceleration (PGA) (from Earthquake Acceleration Record ) Peak Ground Velocity (PGV) (from Earthquake Velocity Record ) Peak Ground Displacement (PGD) (from Earthquake Displacement Record ) Duration of Ground motion and Frequency content
  • 18. 1.3.2. Earthquake Measures Magnitude g  Measured for the Amount of Strain Energy Released  Logarithm (Base 10) of maximum amplitude measured in micrometers of the earth record obtained from Wood-Anderson seismograph corrected to distance of 100 km  Less than 5 No structural damage is expectedProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 19. 1.3.2. Earthquake Measures Frequency & Energy q y gyProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 20. 1.3.2. Earthquake Measures Frequency & Description q y p Richter Frequency of Desc. Earthquake effects M occurrence <20 2.0 Micro Micro earthquakes not felt [6] earthquakes, felt. 8,000 8 000 per day 2.0–2.9 Generally not felt, but recorded. 1,000 per day Minor 3.0–3.9 Often felt, but rarely causes damage. 49,000 per year Noticeable shaking of indoor items, rattling noises. 4.0 4.9 4.0–4.9 Light 6,200 per year Significant d Si ifi damage unlikely. lik l Can cause major damage to poorly constructed 5.0–5.9 Moderate buildings over small regions. At most slight damage to 800 per year well-designed buildings. g g Can be destructive in areas up to about 160 kilometres 6.0–6.9 Strong 120 per year (100 mi) across in populated areas. 7.0–7.9 Major Can cause serious damage over larger areas. 18 per year Can C cause serious damage in areas several hundred i d i lh d d 8.0–8.9 1 per year Great miles across. 9.0–9.9 Devastating in areas several thousand miles across. 1 per 20 years Never recorded; see below for equivalent seismic q Extremely rare y 10.0+ 10 0+ Massive energy yield. (UnknownProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 21. 1.3.2. Earthquake Measures Frequency & Description q y p Richter TNT for Joule Example App. M Seismic Energy equivalent 0.0 00 15.0 (0.529 15 0 g (0 529 oz) 63.1 63 1 kJ 1.5 2.67 kg (5.88 lb) 11.2 MJ World War II conventional bombs 3.5 2.67 metric tons 11.2 GJ Chernobyl nuclear disaster, 1986 4.0 15.0 metric tons 63.1 GJ Small atomic bomb 4.5 84.4 metric tons 355 GJ Tajikistan earthquake, 2006 6.0 15.0 kilotons 62.7 TJ Double Spring Flat earthquake (Nevada, USA), 1994 6.5 84.4 kilotons 355 TJ Eureka earthquake (California, USA), 2010 6.6 66 119 kilotons 501 TJ San Fernando earthquake (California USA), 1971 (California, USA) 6.7 168 kilotons 708 TJ Northridge earthquake (California, USA), 1994 7.5 2.67 megatons 11.2 PJ Kashmir earthquake (Pakistan), 2005 8.1 21.2 megatons 89.1 PJ Guam earthquake, August 8, 1993[12] 8.35 (app.) 50 megatons 210 PJ Tsar a - Largest thermonuclear weapon ever tested 8.8 238 megatons 1.00 EJ Chile earthquake, 2010 9.0 474 megatons 2.00 EJ Sendai earthquake and tsunami (Japan), 2011 9.5 95 2.67 2 67 gigatons 11.2 11 2 EJ Valdivia earthquake (Chile), 1960 (Chile) 10.0 15.0 gigatons 63.1 EJ Never recordedProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 22. 1.3.2. Earthquake MeasuresHuge Events g Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 23. 1.3.2. Earthquake Measures The Modified Mercalli intensity y I. Instrumental  Not felt by many people unless in favourable conditions. (2) Felt only by a few people at best, especially on the upper floors  II. Feeble (2) of buildings. Delicately suspended objects may swing. Felt quite noticeably by people indoors, especially on the  upper floors of buildings. Many do not recognize it as an  III. Slight (3) earthquake. Standing motor cars may rock slightly. Vibration  similar to the passing of a truck. Duration estimated. i il t th i f t k D ti ti t d Felt indoors by many people, outdoors by few people during  h d A i h k d Di h i d d the day. At night, some awakened. Dishes, windows, doors  IV. Moderate (4) disturbed; walls make cracking sound. Sensation like heavy  truck striking building. Standing motor cars rock noticeably.  Dishes and windows rattle alarmingly. Dishes and windows rattle alarminglyProf.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 24. 1.3.2. Earthquake Measures The Modified Mercalli intensity y Felt outside by most, may not be felt by some outside in non- V. Rather favourable conditions. Dishes and windows may break and large Strong (4) bells will ring. Vibrations like large train passing close to house. g g p g Felt by all; many frightened and run outdoors, walk unsteadily. VI. Strong Windows, dishes, glassware broken; books fall off shelves; some ( ) (5) heavy furniture moved or overturned; a few instances of fallen y ; plaster. Damage slight. Difficult to stand; furniture broken; damage negligible in building of good design and construction; slight to moderate in VII. Very well-built ordinary structures; considerable damage in poorly Strong (5-6) built or badly designed structures; some chimneys broken. Noticed by people driving motor cars. yp p g Damage slight in specially designed structures; considerable in VIII. ordinary substantial buildings with partial collapse. Damage Destructive g great in p poorly built structures. Fall of chimneys, factory stacks, y y, y , (6) columns, monuments, walls. Heavy furniture moved.Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 25. 1.3.2. Earthquake Measures The Modified Mercalli intensity y General panic; damage considerable in specially designed structures, well designed frame structures thrown out of plumb. IX. Ruinous (7) Damage great in substantial buildings, with p g g g, partial collapse. p Buildings shifted off foundations. Some well built wooden structures destroyed; most masonry and X. Disastrous (7) X Di frame structures destroyed with foundation. Rails bent. XI. XI Very Few, Few if any masonry structures remain standing. Bridges standing Disastrous (8+) destroyed. Rails bent greatly. Total damage - Everything is destroyed Total destruction Lines destroyed. destruction. XII. Catastrophic of sight and level distorted. Objects thrown into the air. The (8+) ground moves in waves or ripples. Large amounts of rock move position.Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr
  • 26. 1.3.2. Earthquake MeasuresPGD – PGV - PGA El Centro 1940 San Fernando 1971 North Bridge 1994Prof.Dr. Osman Shaalan Earthquake Engineering Dr. Tharwat Sakr