11. Seismic waves: When an earthquake occurs , it releases the stored-up energy in seismic waves that travel away from focus. There are several types of seismic waves as: Body waves Surface waves
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14. Typical speeds are 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite.
15. S waves (secondary waves) are transverse or shear waves, which means that the ground is displaced perpendicularly to the direction of propagation.
16. The velocity of S-waves ranges from 2–3 km/s in light sediments and 4–5 km/s in the Earth's crust up to 7 km/s in the deep mantle.
17. S waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses
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19. They travel more slowly than body waves coz of their low frequency, long duration, and large amplitude.
20. They can be the most destructive type of seismic wave.
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22. They are slower than body waves, roughly 90% of the velocity of S waves.
23. Rayleigh waves have been assertedto be visible during an earthquake in an open space.
24. Love waves are surface waves that cause horizontal shearing of the ground.
25. They are named after A.E.H. Love, a British mathematician who created a mathematical model of the waves in 1911.
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27. Earthquakes occurring at a depth of less than 70 km are classified as 'shallow-focus' earthquakes.
28. while those with a depth between 70 and 300 km are commonly termed 'mid-focus' or 'intermediate-depth' earthquakes.
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30. An aftershock is in the same region of the main shock but always of a smaller magnitude.
31. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock.
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36. Effects/impacts of earthquakes: The effects of earthquakes include, but are not limited to, the following: Shaking and ground rupture Landslides and avalanches Fires Soil liquefaction Tsunami Floods Tidal forces Human impacts
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38. Earthquake prediction : An earthquake prediction is a prediction that an earthquake of a specific magnitude will occur in a particular place at a particular time. Despite considerable research efforts by seismologists, scientifically predictions cannot yet be made to a specific hour, day, or month but for well-understood faults, the probability that an earthquake of a given size will affect a given location over a certain number of years.
39. Once an earthquake has already begun, early warning devices can provide a few seconds' warning before major shaking arrives at a given location.
