Natural Phenomenon

NATURAL PHENOMENON

A natural phenomenon is not a man-made event. Examples include sunrise, weather (fog, hurricanes, tornadoes), biological processes (decomposition, germination), physical processes (wave propagation, conservation of energy, erosion), tidal flow, and include natural disasters such as electromagnetic pulses, volcanic eruptions, earthquakes.

Various types of natural phenomena occur, including (but not limited to) the following:

• Geological phenomena (volcanic activity and earthquakes)
• Meteorological phenomena (hurricanes, thunderstorms, and tornadoes)
• Oceanographic phenomena (tsunamis, ocean currents and breaking waves)

Exposure to forces of nature resulted in about 214,000 deaths in 2010 up from 31,000 in 1990.

EARTHQUAKE

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

Earthquakes are measured using observations from seismometers. The moment magnitude is 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 the Richter 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. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (as of October 2012), and it was the largest Japanese earthquake since records began. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

In its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.

 

Effects of Earthquake

1. Shaking and ground rupture

2. Landslides and avalanches

3. Fires

4. Soil liquefaction

5. Tsunami

6. Floods

7. Human impacts

   An earthquake may cause injury and loss of life, road and bridge damage, general property damage (which may or may not be covered by earthquake insurance), and collapse or destabilization (potentially leading to future collapse) of buildings. The aftermath may bring disease, lack of basic necessities, and higher insurance premiums.

    

              

 

 

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