Natural disastersBy; devina vinay and anwita vinay
When our life is in harmony with nature , things seem to be smooth and pleasant. When living things on earth become victims of natures fury we say that a natural disaster has happened. Natural disasters may destroy a part of life and property. Some such disasters which might affect our lives are earthquakes , volcanoes , tidal waves and drought.
earthquakesEarthquakes are measured using observations fromseismometers. Themoment magnitudeis the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as theRichter magnitude scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. Intensity of shaking is measured on the modifiedMercalli scale. The shallower an earthquake, the more damage to structures it causes,all else being equal.
Volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle.
Tidal wavesA storm surge, or tidal surge, which can cause waves that breach flood defences. A tsunami, a series of water waves in a body of water caused by the displacement of a large volume water, although this usage of "tidal wave" is not favored by the scientific community because tsunamis are not tidal in nature.
droughtA drought is a period of below-average precipitation in a given region, resulting in prolonged shortages in its water supply, whether atmospheric, surface water or ground water. A drought can last for months or years, or may be declared after as few as 15 days.