The Solid Truth

By Chelsea Nevin

There are many cities that have disappeared into the ocean over the centuries. One such city is featured in the Pirates of the Caribbean films. Port Royal is home to William Turner, Elizabeth Swan and the British Navy. Disney captures the essence of this town though they downplayed the violence and sexual content that this town was infamous for. In reality, Port Royal was described as being the richest and the wickedest city, with brothels and bars occupying nearly a quarter of the town. Port Royal was known for its trade as well as having a strong presence of pirates. Pirates were employed to protect the city from enemies of England that might try to cease the town. Unfortunately, on June 7th, 1692, Port Royal was hit with an earthquake, which was followed by a tsunami. Two-thousand lives were taken as Port Royal fell victim to liquefaction. Today, the city sits underwater along with hundreds of sunken ships. 

Liquefaction, also known as soil liquefaction or earthquake liquefaction, is when soil loses its strength and behaves as a liquid; it exhibits the properties of quicksand. Due to the unstable conditions of the ground, buildings will either collapse or tilt, if they are anchored to pavement. It can cause pavement to shatter and cars to be submerged into the ground. In cases like Port Royal, cities can plunge underwater. China, Mexico City, and San Francisco are among other locations that have been affected by liquefaction. These cities are at risk because they sit on water-saturated soil that is not meant to withhold so much weight.

Liquefaction usually occurs after an earthquake in “water saturated unconsolidated soils.”(Rafter). Sometimes construction in areas where the ground has a high saturation of water, can cause liquefaction, but it is not as common. Unconsolidated soil contains loose materials such as clay, sand, gravel, etc. The layers that are affected by liquefaction are comprised of three layers; there is the ground surface (this can be grass or pavement), the sediment layer, and the water-saturated layer.

In the water-saturated layer, particles are packed and pressed together while water fills any open spaces. If too much water fills these spaces, the water will drain into areas where the pressure is low. The vibrations from an earthquake cause high water pressure that forces the particles to spread apart, essentially weakening the soil. Because the water pressure is so high, it has no other choice but to go up. The water and this granular soil move upward as it disrupts the other layers of the ground.

There are methods to reduce liquefaction, though mother nature is a force never to be reckoned with.  An article from Geography and You suggests avoiding construction where saturated soils are found. This means surveying the land as well as soil mapping and studying prior to construction. The next is to build a “structural system” that can withstand liquefaction, which is near to impossible. The last is to improve soil conditions, which would involve compressing the soil.

Like most disasters, it is impossible to prepare for. Weather conditions such as tornados and earthquakes are impulsive, and their aftermaths are even more unpredictable. Who knows how different life would be if Port Royal never sank into the ocean?

References:

Davis, Nick, Jamaica’s ‘Wickedest City’ Port Royal Banks on Heritage,” BBC News. July 25 2012. https://www.bbc.com/news/world-latin-america-1860135

Rafferty, John P. “Soil Liquefaction” Encyclopedia Britannica, 1 June 2016. https://www.britannica.com/science/soil-liquefaction

“Soil liquefaction.” Youtube, uploaded by Minute Earth 2013. https://www.youtube.com/watch?v=4Uwxr42JqYQ

“What is Soil liquefaction? Causes, Effects and Measures,” Geography and You, 10 May 2018.     https://www.geographyandyou.com/science/what-is-soil-liquefaction/



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