19-03-2014, 03:43 PM
A Natural Disaster
Natural Disaster.pptx (Size: 320.41 KB / Downloads: 20)
DEFINITION
An earthquake is a series of vibration induced in the earth crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating . It is also some thing that is severely disruptive and upheaval. The science of earthquake is called seismology which is coming from the Greek word ‘ seismos ’ meaning an ‘earthquake’ and ‘logos’ meaning ‘science’.
Foreshock(s) - is (are) the earthquake(s) generated at or very near the focus of the main earthquake disturbance and prior to the main shock.
Aftershock(s) - is (are) the earthquake(s) generated at or very near the focus of the main earthquake disturbance and following the main shock---the aftershock(s) is (are) smaller in magnitude than the main shock but may be of substantial magnitude and follow the main earthquake by a short or substantial time interval
Main shock - is the main earthquake disturbance generated at the focus
Earthquake Waves
Types of waves
1.Body waves : it travels below the earth’s surface.
Body waves are of two types.
Primary waves: it moves essentially in a straight line path.