Earthquake felt in Chennai - a few minutes ago

Wednesday 11^th of April 2012 - @ around 14.10 hrs

Earthquake  occurred at certain places,  could be easily felt in Office.  Could feel some movement, sort of shaking of the ground under the feet.

Those inside the office realized and as afterthought started moving outside their premises and gathered on roads and infront of building.  There was some fear, though not many exhibited the same.

Clearly no one had any clue as to do what next ! – almost everyother person was seen talking on mobile to dear, near and known persons – conveying their perception and asking others to be safe.

Fortunately, there appeared to be no panic reaction nor spreading of rumours.  Some state that the earthquake was felt throughout the city and in many parts of the State.  The size and magnitude of the quake is not known and it does not appear to have caused any damage.

Chennai houses many old buildings and some flyovers and how safe or how prepared are we – often would have no answers !

News reports suggest that a magnitude 8.9 earthquake struck off the West coast of Northern Sumatra in Indonesia according to US Geological Survey.  Indonesia issued tsunami warning off Aceh Province.  This in Indian time is 2:08:38  and was at 02.38.38 pm at the epicenter i.e., Indonesia.

With regards – S. Sampathkumar

Subsequent Update :

After Sunday, 26 December 2004,  Tsunami has become household name and everyone has started speaking on it whenever an earthquake is reported.  Tsunamis are indeed rarest of rare phenomenons. 

There are reports that India has issued a tsunami warning for the Andaman and Nicobar Islands, located in the Indian Ocean, after a massive earthquake off the coast of Sumatra.   It is reported that the Indian National Centre for Ocean Information Service issued a red high-level warning for the islands, and also put out lower alerts for the coasts of Andhra Pradesh and Tamil Nadu states in the southeast of the country.

A Tsunami warning system (TWS) is used to detect tsunamis in advance and issue warnings to prevent loss of life and damage.  Tsunamis are ocean waves produced by earthquakes or underwater landslides. The word is Japanese and means "harbor wave," because of the devastating effects these waves have had on low-lying Japanese coastal communities. Tsunamis are often incorrectly referred to as tidal waves, but a tsunami is actually a series of waves that can travel at speeds averaging 450 (and up to 600) miles per hour in the open ocean.  From an initial tsunami generating source area, waves travel outward in all directions much like the ripples caused by throwing a rock into a pond. As these waves approach coastal areas, the time between successive wave crests varies from 5 to 90 minutes. The first wave is usually not the largest in the series of waves, nor is it the most significant.

Tsunami Watch  is an alert issued to areas outside the warned area. The area included in the watch is based on the magnitude of the earthquake. For earthquakes over magnitude 7.0, the watch area is 1 hour tsunami travel time outside the warning zone. For all earthquakes over magnitude 7.5, the watch area is 3 hours tsunami travel time outside the warning zone. The watch will either be upgraded to a warning in subsequent bulletins or will be cancelled depending on the severity of the tsunami.

Tsunami Warning - Indicates that a tsunami is imminent and that coastal locations in the warned area should prepare for flooding. The initial warning is typically based on seismic information alone. Earthquakes over magnitude 7.0 trigger a warning covering the coastal regions within 2 hours tsunami travel time from the epicenter. When the magnitude is over 7.5, the warned area is increased to 3 hours tsunami travel time. As water level data showing the tsunami is recorded, the warning will either be cancelled, restricted, expanded incrementally, or expanded in the event of a major tsunami

It is better to be careful and prepared but is more important not to spread rumours and misinformation.