Tuesday, October 21, 2014

Tsunami Versus Storm Surge

by Antonio C. Antonio
October 15, 2014

Why is it important to know and understand tsunamis and storm surges?  Are they the same?  Or are they different?  Why are they destructive forces of nature? 

Let’s focus on a recent event… Typhoon Yolanda (international name: Haiyan) which killed over 8,000 people in the Philippines.  Days before the typhoon made landfall in November 8, 2013, national and local government officials were quick to warn coastal residents in the Central Visayan region that the possibility of storm surge loomed large.  As it turned out, storm surge was a less understood and known term and a lot of residents in the City of Tacloban, Leyte did not bother with the warnings.  Today, the question still haunts authorities whether it could have been better if the term “tsunami” (which is a more known term) was used.  Some even say that the “end could have justified the means” and the interchangeable use of these terms could have saved lives; Meaning: If tsunami was a more popular term, why not use it to warn people… if this could have prodded them to act with dispatch and seriousness?  Well… Typhoon Yolanda is behind us but there has to be a better understanding of these natural occurrences from now on; unless we want to again experience the Tacloban tragedy in other places in the archipelago.

“Tsunami” and “storm surge” are terms that are often confused to be the same.  They are, of course, the same in effect, nature and character but radically different in origin and cause.  Tsunamis and storm surges are caused by different events but both result in flooding and damage to coastal areas.  Both start small but have immense sea waves that could go as high as 10 meters.  Vessels along their paths are the first to be affected but the most damage occurs when they reach coastal areas and communities.

Tsunamis, also known as seismic sea waves, are caused by underwater events such as earthquakes, land and mudslides, volcanic eruptions and explosions.  These events cause massive volumes of water which have to go somewhere.  From the center of these activities, waves are produced and as these waves travel outward, they increase in speed and magnitude.

Storm surges are elevated sea levels produced by intense low pressure systems from the open sea.  They are also called coastal floods.  Storm surges are associated with tropical typhoons originating from the Central Pacific Ocean region where ocean temperature is influenced by the warm tides coming from the African Continent.  These low pressure situations are not likely to intensify into tropical storms as they move westward… although in a few cases, like Yolanda, they become monstrous.  The typhoon sucks up warm sea water which results to higher sea level within the storm’s circumference.  The typhoon, now accompanied with large ocean waves, will certainly wreak havoc when it makes landfall… as in the case of Tacloban City.

Knowledge on the difference and similarity between tsunami and storm surge is critical to Filipinos since we live in an archipelago and an earthquake belt.  Hopefully, next time, we need not debate and crack our brains on which term to use: “tsunami” versus “storm surge”.

Just my little thoughts…

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