M1 Earthquakes, Volcanoes, and Tsunamis PDF

M3. Earthquakes, Volcanoes, and Tsunamis UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg Outline Earthquakes: geology and seismology Volcanoes: formation, activities, and monitoring Tsunamis: generation mechanism, impact, and monitoring Geol...

M3. Earthquakes, Volcanoes, and Tsunamis UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg Outline Earthquakes: geology and seismology Volcanoes: formation, activities, and monitoring Tsunamis: generation mechanism, impact, and monitoring Geologic hazards in the Philippines 1990 Luzon Earthquake 1991 Mt. Pinatubo Eruption 2011 Great East Japan Earthquake (東⽇本⼤震災) - Tsunami UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis Objectives In this module you should learn: how faults manifest and generate earthquakes how seismic waves propagate and their use in locating earthquake epicenters how earthquake sizes are estimated UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth’s lithosphere that creates seismic waves (http://www.geologypage.com/2017/10/what-is- earthquake.html#ixzz6EGlTUEtg) - plates are in (very slow) motion that their boundaries are in friction larger buildup larger energy = released (recall static and kinetic friction) UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis EARTHQUAKES I compensatina g as Stresses in rock mass: > manaman , Confining Stress – caused by gravitational - pressure of overlying land mass and lateral earth pressures Tensile (extensional) Stress – pulls rock mass tension apart weak rock is under Compressional Stress – pushes rock mass together Shear Stress – split/sliding of rock mass UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  in stress small increases strain increase in leads to higher EARTHQUAKES permanent deformation ↑ Stresses in rock mass cause accompanying change in volume or strain. The deformation [ stages of stress-strain build up are mainly: & regainthe deformationa end Elastic deformation – recoverable strain Ductile deformation – irrecoverable strain but - no rupture (formation of discontinuity) - Fracture – material ruptures emp. UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES temp. increases / depth 3 lithosphere is the most brittle Material behavior depends on: : and least ductile Temperature – lower temperature, less ductile behavior Confining pressure – lower confining stress, higher tendency for fracture Loading/Strain rate – slower loading/strain rates, more time to accommodate ductile deformation fast Force will brittle properties cause Chemical Composition – mineralogical make-up influences overall behavior Presence of water – increases ductile behavior by reacting with specific minerals in the rock clay reacting wlwater exhibit ductile properties nagiging Flory Kase UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - stress builds up and when the static friction can no longer resist it, the rocks “snap” and release the energy - can also be generated by large scale explosions, underwater mass movement, meteor impacts, volcanic activity in chamber movement of magma UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  extrose beneath , the intersection of the - epicniis O ↑nonoper did of chergy starb , almost always beneath the gon a UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - generated at the boundary of two plates (trench) or two blocks of rock (fault) moving against each other - happen underground and originate from the focus (area where energy was released) - location of focus is described by location on the surface (epicenter) and depth UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis San Andreas Fault FAULT left lateral strike slip Fault UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  ↑ > UST Civil Engineering Department | AY2021T1 | Eng Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  Si gsinher UST Civil Engineering Department | AY2021T1 | Eng Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  normal Fault oblique slip normal Reverse Fault rotational chinges Fault Strike Slip Scissor pivot UST Civil Engineering Department | AY2021T1 | Eng Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis * movement of water in faults minerals that combine bring lines have mineral deposits are to * fault movementOf water er material oungerFanta r tested umunlit yung material if drilled ⑭ ↓ & UST Civil Engineering Department | AY2021T1 | Eng Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  atson caused by upmass : right lateral ↑ Right (left) Left-step in right- lateral slip fault – compression causes uplift of land mass sudden shift to suddenshi right: RIGHT - ↑ STEP STEP (right) Right-step in left lateral slip fault – tension causes cavity I O you are O you are formation there there UST Civil Engineering Department | AY2021T1 | Eng Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis TRANSFORM FAULTS special type of horizontal movement of rock mass/plates lateral to spreading centers or trenches fault identified by J. Tuzo Wilson (Canadian geologist) fracture zones extend from transform faults but plates move in same direction UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - produce vibrations in the ground that can be broken down into four (4) seismic wave types: * used to 1. Pressure/primary (P) waves: 𝑉 = (𝐾 + ⁄ 𝜇)/𝜌 BodyWavese to the the determine & 2. Shear/secondary (S) waves: 𝑉 = 𝜇/𝜌 grounds epicenter , shorter period 3. Love/Quer (Q) waves surface waves 4. Rayleigh waves & longer period where: 𝑉 = velocity of P-wave 𝐾 = incompressibility 𝜇 = modulus of rigidity 𝑉 = velocity of S-wave 𝜌 = density UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  parang slinky toy up and down ocean , waves parang rolling nattravel , Snake walang galaw na humps, Sa bottom UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - larger earthquakes have larger rupture surfaces and release more energy that is manifested in longer-period seismic waves (i.e. surface waves) - surface waves can cause the most damage to built assets and structures UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - seismic motion is measured by a seismometer UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  Howis the earthquake epicenter located? UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  lagtime = by distance covered the seismic waves https://www.iris.edu/hq/files/interactives/HowAreEQLocated_ WalkRunActivity.html The lag time is plotted on the leftmost line and the amplitude on the rightmost. The points are connected and the intersection of the formed line with the middle scale estimates the Richter magnitude. · G · 3. Smth magnitude L largest movement ⑳ lagtime lagtime (left) sample seismogram record (right) nomogram for estimating magnitude on the Richter scale G Richter Scale UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - strength of an earthquake is quantified according to magnitude (e.g. Richter scale , JMA Scale); https://authors.library.caltech.edu/47921/1/1.full%20%281%29.pdf this is determined by the amplitude and distance from the focus in * increase energy - MEASURED is usually 31 times - logarithmic in nature – an increase on the scale corresponds to increase tenfold (10x) increase in magnitude (i.e. amplitude, NOT energy) 1 UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  Richter Scale Average frequency of Mercalli Magnitude Description Average earthquake effects occurrence globally intensity (estimated) Continual/several million 1.0–1.9 Micro I Microearthquakes, not felt, or felt rarely. Recorded by seismographs. per year 2.0–2.9 I to II Felt slightly by some people. No damage to buildings. Over one million per year Minor Often felt by people, but very rarely causes damage. Shaking of indoor objects can be 3.0–3.9 III to IV Over 100,000 per year noticeable. Noticeable shaking of indoor objects and rattling noises. Felt by most people in the affected area. Slightly felt outside. Generally causes zero to minimal damage. Moderate 4.0–4.9 Light IV to VI 10,000 to 15,000 per year to significant damage very unlikely. Some objects may fall off shelves or be knocked over. Can cause damage of varying severity to poorly constructed buildings. Zero to slight 5.0–5.9 Moderate VI to VII 1,000 to 1,500 per year damage to all other buildings. Felt by everyone. Damage to a moderate number of well-built structures in populated areas. Earthquake- resistant structures survive with slight to moderate damage. Poorly designed structures 6.0–6.9 Strong VIII to X 100 to 150 per year receive moderate to severe damage. Felt in wider areas; up to hundreds of miles/kilometers from the epicenter. Strong to violent shaking in epicentral area. Causes damage to most buildings, some to partially or completely collapse or receive 7.0–7.9 Major severe damage. Well-designed structures are likely to receive damage. Felt across great 10 to 20 per year distances with major damage mostly limited to 250 km from epicenter. Major damage to buildings, structures likely to be destroyed. Will cause moderate to X or greater 8.0–8.9 heavy damage to sturdy or earthquake-resistant buildings. Damaging in large areas. Felt One per year Great in extremely large regions. 9.0 and At or near total destruction – severe damage or collapse to all buildings. Heavy damage One per 10 to 50 years greater and shaking extends to distant locations. Permanent changes in ground topography. Based on U.S. Geological Survey documents.  https://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/magnitudeScaleCalculations.html Seismic energy Earthquake energy as a function of magnitude. Magnitude Energy in joules Notes -3.0 2 1 kg dropped 20 cm -2.0 63 -1.0 2000 100 kg person jumps down 2 m 4 0.0 6.3 x 10 6 1.0 2.0 x 10 7 2.0 6.3 x 10 Only felt nearby 9 3.0 2.0 x 10 Energy from 50 litres of petrol 10 4.0 6.3 x 10 Often felt up to 10's of miles away 12 5.0 2.0 x 10 Energy from 50 000 litres of petrol 13 6.0 6.3 x 10 3.3 Hiroshima-size A bombs 15 7.0 2.0 x 10 16 8.0 6.3 x 10 1–2 earthquakes this size each year 18 9.0 2.0 x 10 Total annual energy use of UK MAGNITUDE SCALES mb measured from body- - waves, specifically P- - Ms measured from surface-waves, ML Richter scale measured from the lag time of body waves Mo seismic moment measures the strain energy released G Mw moment magnitude waves that are 1- to specifically Rayleigh and the amplitude; =(average fault adjusted scale used in 10-sec periods waves that are 18- to uses 0.1- to 2-sec displacement) x recent years 22-sec periods period waves (rupture area) x (shear if malayosa station yung strength of faulted eq., hindi underestimates underestimates - restricted to namemeasure rock) energy from large smaller and measuring localized - earthquakes moderately sized - earthquakes with suited for large since disregards it earthquakes moderate size; the earthquakes; takes surface waves wh is more destructive small period waves weeks or months to used are not suited for quantify correctly distant and significantly large earthquakes UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  EARTHQUAKES - the severity of effects on humans and built environment is qualified according an intensity scale (e.g. Modified Mercalli Scale, Rossi-Forel Scale, PHIVOLCS Earthquake Intensity Scale) - PERCEIVED/FELT UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  PHIVOLCS Earthquake Intensity Scale (PEIS) https://www.phivolcs.dost.gov.ph/index.php/earthquake/earthquake-intensity-scale Intensity Scale Shaking Description I Scarcely Perceptible Perceptible to people under favorable circumstances. Delicately balanced objects are disturbed slightly. Still Water in containers oscillates slowly. II Slightly Felt Felt by few individuals at rest indoors. Hanging objects swing slightly. Still Water in containers oscillates noticeably. III Weak Felt by many people indoors especially in upper floors of buildings. Vibration is felt like one passing of a light truck. Dizziness and nausea are experienced by some people. Hanging objects swing moderately. Still water in containers oscillates moderately. IV Moderately Strong Felt generally by people indoors and by some people outdoors. Light sleepers are awakened. Vibration is felt like a passing of heavy truck. Hanging objects swing considerably. Dinner, plates, glasses, windows and doors rattle. Floors and walls of wood framed buildings creak. Standing motor cars may rock slightly. Liquids in containers are slightly disturbed. Water in containers oscillate strongly. Rumbling sound may sometimes be heard. V Strong Generally felt by most people indoors and outdoors. Many sleeping people are awakened. Some are frightened, some run outdoors. Strong shaking and rocking felt throughout building. Hanging objects swing violently. Dining utensils clatter and clink; some are broken. Small, light and unstable objects may fall or overturn. Liquids spill from filled open containers. Standing vehicles rock noticeably. Shaking of leaves and twigs of trees are noticeable. VI Very Strong Many people are frightened; many run outdoors. Some people lose their balance. motorists feel like driving in flat tires. Heavy objects or furniture move or may be shifted. Small church bells may ring. Wall plaster may crack. Very old or poorly built houses and man-made structures are slightly damaged though well-built structures are not affected. Limited rockfalls and rolling boulders occur in hilly to mountainous areas and escarpments. Trees are noticeably shaken. VII Destructive Most people are frightened and run outdoors. People find it difficult to stand in upper floors. Heavy objects and furniture overturn or topple. Big church bells may ring. Old or poorly-built structures suffer considerably damage. Some well-built structures are slightly damaged. Some cracks may appear on dikes, fish ponds, road surface, or concrete hollow block walls. Limited liquefaction, lateral spreading and landslides are observed. Trees are shaken strongly. (Liquefaction is a process by which loose saturated sand lose strength during an earthquake and behave like liquid). VIII Very Destructive People are panicky. People find it difficult to stand even outdoors. Many well-built buildings are considerably damaged. Concrete dikes and foundation of bridges are destroyed by ground settling or toppling. Railway tracks are bent or broken. Tombstones may be displaced, twisted or overturned. Utility posts, towers and monuments mat tilt or topple. Water and sewer pipes may be bent, twisted or broken. Liquefaction and lateral spreading cause man- made structure to sink, tilt or topple. Numerous landslides and rockfalls occur in mountainous and hilly areas. Boulders are thrown out from their positions particularly near the epicenter. Fissures and faults rapture may be observed. Trees are violently shaken. Water splash or stop over dikes or banks of rivers. IX Devastating People are forcibly thrown to ground. Many cry and shake with fear. Most buildings are totally damaged. bridges and elevated concrete structures are toppled or destroyed. Numerous utility posts, towers and monument are tilted, toppled or broken. Water sewer pipes are bent, twisted or broken. Landslides and liquefaction with lateral spreadings and sandboils are widespread. the ground is distorted into undulations. Trees are shaken very violently with some toppled or broken. Boulders are commonly thrown out. River water splashes violently on slops over dikes and banks. X Completely Devastating Practically all man-made structures are destroyed. Massive landslides and liquefaction, large scale subsidence and uplifting of land forms and many ground fissures are observed. Changes in river courses and destructive seiches in large lakes occur. Many trees are toppled, broken and uprooted. Questions After this module you should be able to answer the following: Foot wall wall Slip Fault Plane hanging What are the anatomy of a fault? its different types? , , , > - slip , oblique normal , reverse , strike snake a moving humps & What are the types of seismic waves and how do they propagate? Raileigh) > - surface (Love destructive - b more waves How are earthquake epicenters located? the radius of the distance of the EQ Body (P and s getting > -. Following in diff. areas. The intersection of the circlesis 1st , higher amplitude felt the epicenter How can the magnitude of an earthquake be estimated?W lag (P-waves) the time by obtaining Richter magnitude amplitude (s-waves) then use and peak height of , scale UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis  “It takes an earthquake to remind us that we walk on the crust of an unfinished planet.” - Charles Kuralt UST Civil Engineering Department | AY2021T1 | Engr. Rajiv Eldon E. Abdullah, MEngg | CE2234 Disaster Science | M3. Earthquakes, Volcanoes, and Tsunamis