by punjabedupoint

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Published Mar 6, 2014 in Business & Management
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Presentation Slides & Transcript

Presentation Slides & Transcript

Earthquakes"An earthquake is the way the Earth relieves its stress by transferring it to the people who live on it." ?1

What is Earthquake???An earthquake is a sudden movement or shaking of the earth’s crust caused by the rapid release of energy that is stored in rocksEarthquakes are produced by abrupt motion along fault when friction that resists such motion is overcome by stress2

What is Earthquake???3

What causes earthquakes and where do they happen?The earth has four major layers: the inner core, outer core, mantle and crustThe crust and the top of the mantle make up a thin skin on the surface of our planet. This skin is not all in one piece These puzzle pieces keep slowly moving around, sliding past one another. These puzzle pieces are called tectonic plates, and the edges of the plates are called the plate boundariesThe locations of earthquakes generally coincide with the boundaries of lithospheric plates4

How earth releases the stored energy?When an earthquake occurs, it releases the stored up energy in seismic waves that travel away from the focusBody WavesSurface Waves5

Measurement of Seismic WavesEarthquakes are recorded by instruments called seismographs The recording seismographs make is called a seismogram6

Locating the EpicenterEstimate the time interval between the arrival of the P and S waves (the S-P interval) on the seismograms from at least three different stations7

Locating the Epicenter8Travel-time curve are use to calculate the distance between an earthquake epicenter and a seismograph

Locating the Epicenter9The distance defines a circle around the receiving station. The radius of each circle equals that station distance from the earthquake epicenter. The epicenter is where the circles intersect

Magnitude of EarthquakeThe magnitude is a number that characterizes the relative size of an earthquakeMagnitude measures the energy released at the source of the earthquake. Magnitude is determined from measurements on seismographs10

Magnitude of Earthquake11In 1935 Charles Richter devised the Richter scale to express the amount of energy released during an earthquake

Magnitude of Earthquake12

Magnitude of EarthquakeThere is a rough correlation between the amount of energy released during an earthquake and the magnitude of the earthquake:Energy (joules) = 10 to the power of (5.24 + (1.44 x Magnitude)) E = 10^(5.24 + (1.44 x M))13

Magnitude of EarthquakeThe moment magnitude scale is the most recent scale and was introduced in 1979 by Hanks and Kanamori Rather than relying on measured seismogram peaks, the Mw scale is tied to the seismic moment (M0) of an earthquakeThe seismic moment is defined as14

Magnitude of Earthquake15where Mw is the moment magnitude and M0 is the seismic moment (in displacement along the fault during earthquakeA= size of area that slippedS= strength of rock Moment magnitude is calculated from seismic moment using the relation of Hanks and Kanamori (1979)

Intensity of EarthquakeIntensity measures the strength of shaking produced by the earthquake at a certain locationIntensity is determined from effects on people, human structures, and the natural environmentMercalli Intensity scale is the most widely applied intensity scale16