8. SEISMOGRAPH Seismograph is an instrument which is used to detect,measure and record seismic waves. Invented by Charles Richter. (1935) It measures and determines the magnitude of an earthquake
14. Magnitude Frequency Per Year Great 8.0 + 1 Major 7 -7.9 18 Large 6-6.9 120 Moderate 5-5.9 1000 Minor 4-4.9 6,000 Generally Felt 3-3.9 49,000 Potentially Perceptible 2 – 2.9 300,00 Inperceptible less than 2 600,000+
15. SEISMIC WAVES The energy released by an earthquake travels through the earth. The speed of a seismic waves depends on the density and elasticity of the material through which they travel.
16. TYPES OF SEISMIC WAVES Body waves Surface waves P -WAVES S – WAVES R -WAVES L – WAVES
17. BODY WAVES Speed decreases with increasing density of rock and increases with rock elasticity
18. P –WAVES (PRIMARY WAVES) Compressional waves that vibrate parallel to the direction of wave movement. Travels through all medium. Fastest seismic waves.
19. S – WAVES (Secondary waves) Also known as shear waves. Vibrate perpendicular to the direction of wave movement. Travel only on solid.
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21. R – WAVES (Rayleigh waves) Behave like water waves with elliptical motion of material in wave. Generally slower than L waves.
29. Kobe Earthquake In January 1995 a road connecting Kôbe with Osaka collapsed during the most deadly earthquake to hit Japan since 1923. The quake ignited firestorms and caused massive destruction in Kôbe. In all, more than 5,000 people were killed and hundreds of thousands were left homeless .
30. Alaskan Earthquake The Alaskan earthquake of 1964 was rated 9.2 on the Richter scale. One of the most powerful earthquakes ever known to hit North America, it claimed 131 lives and devastated parts of Anchorage and Valdez. The quake destroyed foundations and left gaping cracks in the cement of this street.
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34. MAJOR E’Q IN INDIA 7.7 Bhuj 2001 6.3 Killar 1993 6.5 Uttarkashi 1991 6.3 Koyana 1967 8.7 Assam 1950 7.6 Quetta 1935 8.4 Bihar-Nepal 1934 8.6 Kangra 1905 8.7 Assam 1897 8.0 Kutch 1819 Magnitude Location Year
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36. Seismic Zones There are five seismic zones named as I to V as details given below:- Zone V : Covers the areas liable to seismic intensity IX and above on Modified Mercalli Intensity Scale. This is the most severe seismic zone and is referred here as Very High Damage Risk Zone. Zone IV : Gives the area liable to MM VIII. This, zone is second in severity to zone V. This is referred here as High Damage Risk Zone. Zone III : The associated intensity is MM VII. This is termed here as Moderate Damage Risk Zone. Zone II : The probable intensity is MM VI. This zone is referred to as Low Damage Risk Zone. Zone I : Here the maximum intensity is estimated as MM V or less. This zone is termed here as Very Low Damage Risk Zone
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38. Global Positioning System (GPS): A system of Earth-orbiting satellites, each providing precise time and position information which enables GPS receiving devices to compute positions on the Earth. Signals must be received from at least three satellites in order to establish the receiver’s position in latitude and longitude, or according to a national coordinate system provided by the equipment. Measurements from a fourth satellite are required to calculate altitude (height) position.
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41. Rupture in seafloor pushes water upwards starting the wave Wave moves rapidly in deep ocean reaching speed up to 500km/h Wave heads inland destroying all its path As the wave nears land it Slows up to 45km/h But is squeezed upwards increasing in height
