Earthquake Prof. R. Nagarajan, CSRE , IIT Bombay GNR 639 GNR 639 : - - PowerPoint PPT Presentation

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Lesson 2 Earthquake

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake is the result of a sudden release of energy (seismic waves) in the Earth's crust, caused by sudden breaking and movement of large sections (tectonic plates) of the earth's crust. Most earthquakes occur along the fault lines when the plates slide past each other or collide against each other. The seismicity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. This movement of masses generate shock waves that may be powerful enough to

• alter the surface of the Earth, thrusting up cliffs and opening great cracks in the

ground and

• cause great damage - collapse of buildings, man-made structures, broken power

and gas lines and the consequent fire, landslides, snow avalanches, tsunamis and volcanic eruptions.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

(Source courtesy: usgs)

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake frequency - High Magnitudes

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Types of earthquake

Tectonic Earthquakes when rocks in the earth's crust break due to geological forces created by movement of tectonic plates. Volcanic Earthquakes occur in conjunction with volcanic activity. Explosive Earthquakes result from the explosion of nuclear and chemical devices. Collapse Earthquakes are small earthquakes in underground caverns and mines.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Tectonic earthquakes

Continental plates converge, diverge or grind past each other (transform fault). Earthquakes are caused by a sudden release of stress along faults in the crust. Due to continuous motion of tectonic plates, stress builds in the rock on both sides of a fault. Most of them happen where tectonic plates meet and glide against each other due to the frictional stress of the movement exceeds the strength of the rocks, causing a failure at a fault line. Violent displacement of the Earth's crust follows, leading to a release of elastic strain energy. Fault or fault plane = the surface where when two blocks of the earth suddenly slip past one another

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GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Geological faults

San Andrea’s fault California; Displacement of beds

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Epicenter is the point on the Earth's surface directly above the point where the fault begins to rupture. It is the area of greatest damage. However, in larger events, the length of the fault rupture is much longer, and damage can be spread across the rupture zone. Hypocenter (also know as focus) is the point within the earth where an earthquake rupture starts. The epicenter is the point directly above it at the surface of the Earth. Seismic waves propagate spherically out from the hypocentre. Seismic waves - an elastic wave by an earthquake or other means. Seismic waves: P (primary) waves, S (secondary) waves and surface waves, which arrive at seismic recording stations one after another. Both P and S waves penetrate the interior of the Earth while surface waves do not, hence, they are body waves.

Source courtesy: scwcweb.cwb.gov.tw

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

P waves – Compressional, longitudinal waves. Travel at 1.5-8 km/sec in the Earth's crust and first to arrive at seismic stations They shake the ground in the direction they are propagating. Travel through the Earth's core S waves - shear waves slower than P waves, 2nd to arrive at seismic stations. Shake the ground perpendicular to the direction in which they are propagating & do not travel through liquid (ie. water, molten rock, the Earth's outer core) Surface waves (Love & Rayleigh)– travels only on earth’

• surface. moves ups and down like ocean waves. Slowest of all

Source courtesy: colarado.edu

(Source courtesy:ndma.gv.pk)

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Human induced seismicity

Induced seismicity is a minor low magnitude earthquakes and tremors that are caused by human activity that alters the stresses and strains on the Earth's crust.

Source courtesy: en.wikipedia.org

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Reservoir-induced seismic activity appears to occur on dams with heights more than 100 m. The extra water pressure created by large reservoirs is the most accepted explanation for the seismic activity. World Commission on Dams, Reservoir-Induced Seismicity (RIS) is related to the extra water pressure created in the micro-cracks and fissures in the ground . Hydraulic fracturing has a low risk for inducing earthquakes that can be felt by

• people. Underground injection of wastewater produced by hydraulic fracturing

and other energy technologies has a higher risk of causing such earthquakes.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Artificial lakes

Creation of deep artificial lake ( high Water column) alters in-situ stress along an existing fault . Weight of the water column significantly change the stress on the underlying fault and increase the effective stress through the increased pore water pressure. This stress change can lead to sudden movement resulting in an earthquake

Mining

Large scale Voids alter the balance of forces in the rock, causing rock bursts. These voids may collapse producing seismic waves and also reactivate existing faults causing minor

• earthquakes. Collapse of Natural cavern sinkholes/ natural cavern produce an identical

local seismic event.

Waste disposal wells

Injection of liquids (high-saline water) into waste disposal (salt water disposal (SWD) wells, is practiced in disposing of produced water from oil and natural gas wells. This activity result in increasing the subsurface pore pressure, trigger movement along faults.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Extraction of fossil fuels / groundwater The changes in crustal stress patterns caused by the large scale extraction of groundwater as well fossil fuels has been shown to trigger earthquakes. Geothermal energy Enhanced geothermal systems (EGS), involves pumping fluids at pressure to enhance or create permeability through the use of hydraulic fracturing

• techniques. Hot dry rock (HDR) actively creates geothermal resources

through hydraulic stimulation. Induced seismicity events are reported from the Geysers geothermal field has been strongly correlated with injection data

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Seismometer is an instrument for measures seismic waves that are propagating vibrations that carry energy from the source of an earthquake outward in all directions. They travel through the interior of the Earth and can be measured with sensitive detectors called seismographs. Network of seismometers is used to calculate the magnitude and source of an earthquake in three dimensions: Magnitude: the size of the earthquake Depth: how deep the earthquake was Location: where the earthquake occurred

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Seismograph of earthquake & Nuclear explosion shock waves

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Richter magnitude scale assigns a magnitude number to quantify the energy released by an earthquake. It is a base- 10 logarithmic scale, which defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

(Source courtesy: oliphantearth.com)

Modified Mercalli scale ranks intensity of earthquakes from (barely felt) to 12 (total destruction) Earthquake depth range:

• shallow - 0 and 70 km ,

(result of the sudden release of strain energy built up over

time in rock by brittle fracture and frictional slip over planar surfaces )

• intermediate 70 - 300 km
• deep 300 - 700 km

(Subducted lithosphere subject to the pressure and temperature regime at depths greater than 300 km should not exhibit brittle behavior, but should rather respond to stress by plastic deformation)

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Physical Damage

• Landslides
• Tsunamis
• Fires
• Mudslides
• Liquefaction

Structural Damage

• Buildings Collapse
• Roadways Collapse

Structural damage depends on:

• Strength of the earthquake waves that reach the surface
• Duration of the motion
• Proximity
• Geologic foundation
• Structural design and construction quality

Emotional Damage

• Deaths

people trapped under the rubble and debris. Falling structures and flying glass and other objects striking people

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Source courtesy : db.world-housing.net

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

(Source courtesy: geomexico.com) (Source courtesy: theatlandic.com (Source courtesy: emaze.com) (Source courtesy: borderneapal.wordpress.com)

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

• Ground Motion: Shaking of structures results in damage or total collapse structures
• Liquefaction: Happens in loose saturated cohesion-less soils in which the firm soil is

converted into a fluid state which has no shear strength and thus structures found

• n these soils fail due to loss of bearing capacity of the ground
• Landslides/avalanches: Vibrations during earthquake trigger large slope failures
• Fire, Dust and Pollution : Indirect effect of earthquakes (large scale damage

triggered by EQ to gas pipe line and power lines)

• Tsunamis: large waves created by the instantaneous displacement of the sea floor

during submarine earthquakes

Effects of Earthquakes

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Shaking and ground rupture 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 risk for large engineering structures such as dams, bridges and nuclear power stations and requires careful mapping of existing faults to identify any which are likely to break the ground surface within the life of the structure.[

Effects of earthquake

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Soil liquefaction is a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.

(Source courtesy: ema.alabama.gov)

(Source courtesy: sciblog.co.nz) (Source courtesy: blogs.agu.org) Sendai earthquake Sand ejected through a crack forming a series of sand boils along the railroad tracks in Olympia USGS

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Landslide and avalanches – trigger the slope instability leading to

• landslide. Landslide danger persist even during emergency operations.

Fire is caused by damaging of electrical power or gas lines. In the event

• f water mains rupturing and a loss of pressure, It may also difficult to

stop a fire once it started. Human impacts Injury and loss of life, dust, road and bridge damage, general property damage, and collapse or destabilization of buildings. The aftermath may bring disease, lack of basic necessities, mental consequences such as panic attacks, depression to survivors,[56] and higher insurance premiums.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Tsunamis are long-wavelength, long-period sea waves produced by the sudden or abrupt movement of large volumes of water. In the open ocean the distance between wave crests can surpass 100 km, and the wave periods can vary from five minutes to one hour. Such tsunamis travel 600-800 km/hour, depending on water

• depth. Large waves produced by an earthquake or a submarine landslide can
• verrun 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

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Factors affecting the Impact of Earthquakes:

Depth: If the hypocentre of an earthquake is close to the surface then it is more likely to cause greater damage than a deep earthquake. Duration: A longer earthquake is likely to cause greater damage than an earthquake that lasts only a few seconds. Magnitude: Obviously a stronger earthquake is going to have a greater impact than a weaker one. Time of Day: Time of day can be important. If people are sleeping and get trapped in their beds more people can be killed. In Japan an earthquake that struck while people were cooking their evening dinner caused widespread secondary hazards (fire) that caused more deaths.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Epicentre Location: If the epicentre of an earthquake is an uninhabited region it is going to have a lesser effect than one under a densely populated city. Geology: If an earthquake occurs in solid bedrock it is likely to cause less damage than one centred below an alluvial floodplain which may lead to liquefaction. Economic Development (buildings, planning, preparedness): Generally speak more developed countries have better zonal planning, building codes and preparedness mean the effects of the earthquake are less. Duration: The length of time that a hazard lasts for. As a general rule the longer the hazard the more severe it is likely to be. For example and earthquake that lasts 1 minute is likely to be more severe than one that last two seconds and a drought that lasts ten years is likely to be more severe than one that last three months.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Magnitude: The strength of hazards are measured on a scale - Richter scale The stronger the hazard the more severe the hazard is. Predictability: Earthquakes are much harder to predict. Generally speaking hazards that hit with no warning are going to be more serious. Regularity: If hazards happen often and in quick succession - earthquake followed by multiple aftershocks, then the severity is likely to be greater as the region has not recovered from previous damage. Frequency: The return interval of hazards of certain sizes. For example earthquakes with a magnitude of over 8.0 happen on average once a year, but earthquakes of only 3 or 4 happen many times a day. Speed of onset: If the peak of the hazard arrives quickly (earthquake) and slowly (drought), then it affects heavily.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Spatial concentration: Where hazards are located or centred- earthquakes tended to be focused along plate boundaries. Hazards that are located in known areas can be better prepared for and managed better. Areal extent: If a hazard covers a large area e.g. a drought covering the whole of East Africa, then the severity of the hazard is likely to be more severe, than a flood hitting just one village. Number of hazards: If a location is hit by multiple hazards that the affects can be more severe. Hazard hotspots like Indonesia can be hit by earthquakes, volcanoes, landslides and flooding all simultaneously.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Earthquake prediction depending on time scale

Long term prediction estimates the statistical probability of earthquakes occurring in a 10 to 100years time scale. Intermediate term prediction also estimates the statistical probability of earthquakes

• ccurring, but in a 1 to 10 years time scale.

Short term prediction is up to a few weeks, and is focused on finding precursors. Intermediate-term and long-term predictions are typically based on trend methods such as elastic rebound, characteristic earthquakes, seismic gaps, or seismicity patterns. Earthquake precursor is an anomalous phenomenon for effective warning of an impending

• earthquake. None have been found to be reliable for the purposes of earthquake prediction

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Earthquake Pre-cursor

Unusual Animal behaviour

• Thousands of frogs crossed the road near earthquake area in China

Hibernating animals leaving their underground nests

• Animals becomes restless, refuse to go into dens and move upto higher

elevations

• Birds vacate their nest
• Deep water fish come closer to the surface and shore
• May be due to foreshock activity at magnitudes that most people do not notice.

Change in the well water level

• Sudden changes in water levels. Large surface waves force particles of rock near

to the surface to rise or deplete

• Water levels can be affected by any fault creeps, crust tilts, or other seismic

activity.

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Radon Emission

• Radon is released by the decay of radioactive elements. Its short half-life (3.8

days) makes radon levels sensitive to short-term fluctuations.

• Accumulated radon will be released and dissolved in the ground water when it

is fractured. Hence, sudden increase in radon abundances in streams, well and ground water

Foreshocks before the major Earthquake

• Smaller foreshocks are observed before the main shock is used as the warning

system to ensure safety

Statistical Probability

• Using the past earthquake records, combined with knowledge of the fault

movement the USGS has come up with the probability for the earthquakes >6.7M in San Francisco region.

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GNR 639 : Natural Disaster And Management

Seismic gap

• segment of an active fault known to produce significant earthquakes that has

not slipped in an unusually long time, compared with other segments along the same structure.

• Displacement on any segment must be equal to that experienced by all the
• ther parts of the fault.
• Any large and longstanding gap is, therefore, considered to be the fault segment

most likely to suffer future earthquakes.

Seismic Electric Signals (SES)

• Measures the geoelectric potential differences between electrodes stack into the

ground at desired distances

• Distinguish meaningful pre-seismic signals, if they exist at all, from these noise.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Earthquakes are predicted where they are likely to happen, but not, when they will happen and how strong they will be. The following aspects are considered:

• Micro earthquakes
• Changes in rock stress
• Ground subsidence, uplift or tilt
• Changes in magnetic field and electrical resistivity of rocks
• Animal behaviour
• Seismic history

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Source zonation models

Area source model

• Active shallow and stable continental areal sources
• Subduction interface modeled as complex fault
• Deep areal sources – All activity computed from seismicity – Fault source

and background seismicity model

• Fault sources in 3D
• Background seismicity
• Subduction interface modeled as complex fault
• Deep seismicity – Fault activity computed from slip rates

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Source courtesy:Air-worldwide.com

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Hazard map highlights areas that are likely to be affected or vulnerable

to a particular hazard such as earthquakes, volcanoes, landslides, flooding and tsunamis. It helps to prevent serious damage and deaths.

Seismic hazard is the probability that an earthquake will occur in a

given geographic area, within a given window of time, and with ground motion intensity exceeding a given threshold.

Peak ground acceleration (PGA) is equal to the maximum ground

acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a particular earthquake.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake hazard

• estimate of the probability of exceeding a certain amount of ground shaking / motion in 50 years.

The hazard depends on the magnitudes and locations of likely earthquakes, how often they

• ccur, and the properties of the rocks and sediments that earthquake waves travel through.

National Hazard Maps

• show the distribution of earthquake shaking levels that have a certain probability of occurrence.

They provide the accurate and detailed information in designing buildings, bridges, highways, and utilities that will withstand shaking from earthquakes. They used to create and update the building codes that are used by cities, counties, and local governments. The larger probabilities indicate the level of ground motion likely to cause problems.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Isoseismal map is used to show lines of equal felt

seismic intensity, generally measured on the Modified Mercalli scale. It helps in identifying earthquake epicenters, particularly where no instrumental records exist, such as for historical earthquakes.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Probabilistic map shows possibilities for the future based on the past

by taking into account, geologic and seismic information:

• Past history of small & larger earthquakes on a given fault
• How much Ground shaking past earthquakes produced
• Location and distribution of faults
• Response of Earth and rocks to ground shaking
• How rapidly the Earth is deforming in response to tectonic forces
• Where deformation is occurring.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Source courtesy: Dpadhikary.wordpress.com

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake of magnitude 6.9 on Richter scale; 7.7 Mw (USGS)

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GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Earthquake alert Conditions and observations necessary Stage 1 An approximately defined area is estimated to be more likely than surrounding seismic areas to experience a future earthquake (eg. Seismic gap or occurrence of at least one geophysical, geological or geodetic anomalous observation). Stage 2 One or several crustal parameters show the beginning of a long to medium-term pattern of change known to have occurred before some other earthquakes. At least one of the prediction elements (location, size or time )is still poorly defined (eg. Occurrence time uncertainty is approximately equal to 50 percent of precursor time) Stage 3 Changes in crustal parameters are observed which can be interpreted as indicating that the end of the long-term preparatory process is near (eg the anomalies return to normal). The three prediction elements are fairly well defined (eg. occurrence time uncertainty is less than about 20 percent of precursor time) Stage 4 In addition to the conditions of stage 3,an anomaly is measured which can be interpreted as a short-term precursor. Occurrence time uncertainty may range from hours to weeks.

Stages of Earthquake alert information and observation (Wyss 1981)

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Period of prediction Buildings Material assets Safeguards for human life Special measures Operative (a few hours to

• ne or two

days) Evacuate dangerous buildings; cease activities in places of public assembly Evacuate the most important material assets Allocate emergency equipment in the danger area; prepare medical establishments Cut off electricity and gas mains; shut down nuclear reactors and dangerous chemical plants In the short term(from 2 to 4 months) Estimate probable damages; prepare public evacuation plans Preserve major assets Prepare emergency measures and medical establishments Remove or safeguard hazardous substances; lower reservoir levels, etc In the long term (12 months) Strengthen buildings of particular vulnerability to earthquakes Plan emergency food stores; plan the use to be made of medical establishments Transfer of hazardous substances to other places

• f storage.

Safety measures based on earthquake predictions

(Savarenskij and Neresov 1978)

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management Earthquake early warning systems

• use developments in science and

technology in monitoring earthquake and alert people when shaking waves generated by an earthquake are expected to arrive at a location.

• seconds

to minutes

• f

advance warning information allow people and systems to protective actions in protecting life and property from destructive shaking.

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

(Source courtesy: hellotravel.com) Source courtesy:twitter.com

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Prepare yourself