The Norte Chico civilization of Peru, who built the great city of Caral, are among the earliest civilizations. They stand with the early cities of Mesopotamia and Turkey as among the oldest organized societies ever to exist.
Such glimpses into the dawn of civilization allow us to pick apart how our modern, complex and interwoven society came to be. It allows us to understand what the first priorities of these ancient peoples were, and it would seem that for the Norte Chico, their first problem was earthquakes.
Such events could be entirely destructive to these earliest attempts at building permanent settlements on this scale. But we know the Norte Chico faced these problems, and we know how they dealt with them too. They built shicras.
Their approach was illuminating. The shicra technique may just be the oldest textile production in the entire Andes. It consists of vegetable fiber fabrics, which were used to as bases or fillings for the walls within ceremonial temples and pyramids in the region of Peru.
There is tried and tested research that proves these shicras made the structure anti-seismic and saved them from collapsing due to frequent earthquakes. It is a brilliant technology that dates back to 6000 years ago. Let’s take a deeper look at what this technique has to offer.
The Archaeological Discoveries of Shicra
An archaeologist, Walter Tosso, ran an excavation project around the ancient sites near Pisquillo and named it “The Shicras.” The name wasn’t given to it randomly, but by observing the construction of walls. The walls at the site were still preserving the entire construction. The discovery led them to find large baskets full of stones that were used as a filling to hold the walls.
As per Tosso’s discovery, the constructions were around 3,000 or more years old. There were no signs of collapse, even after enduring numerous earthquakes since that time.
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There was another archaeological excavation at Caral, dating to around 3500 BC, and Tosso gave a verdict that both discoveries were similar to one another. Thus, this resemblance demonstrates that this technique of using shicra and stones for repelling earthquakes was widespread across the pre-Hispanic coast in terms of construction.
Caral is home to one of the oldest civilizations in the world. It was the first place where shicra was discovered. Later, several archaeologists found similar bags full of stones across various ancient sites in Supe, Vichama, Huaura, Aspero and others.
The ancient Peruvians clearly faced serious seismic problems, as the sophistication of the shicra technique shows. And these techniques were developed over the millennia: even today you can see the remnants of the shicra design in the surviving Inca structures in Cusco, with smaller stones at the bottom allowing for flexibility in response to an earthquake.
Experts say that if ancient Peruvians had just used stones without the shicra bag, the weight would significantly increase on the retaining walls, leading the structure to collapse. But, with the shicra bag, the seismic vibrations are spread evenly across the surface, and the earthquake fails to shake the integral strength of the wall.
Construction of pyramids in ancient Peru was followed by the installation of shicras around the site. They probably found the earthquake-resistant technology, which is now modified, upgraded and enhanced in the modern days. The best thing about the shicra concept is that it is today seen in gabions and geogrids.
These modern-day earthquake-resistant techniques are mostly used today as a riparian defense system for rivers or slope containments. But the idea was there, 6,000 years ago.
A Functional Solution
Ancient Peruvians used shicra as stone bags that were placed within the superimposed platforms. It was done for the construction of important enclosures within the building.
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The wall is then built, and shicras are placed or tied onto them with mortar. As it is vegetable fiber and has elastic properties, these shicras create tension throughout the structure, drawing everything together. But, this tension allows the walls to flex when an earthquake hits, bending but not breaking.
Each of the shicra bags wasn’t just placed randomly. They were maintained in a specific order to ensure there was sufficient stability to withstand seismic activities. It is said that this technology helped find the astounding principles of earthquake resistance.
Shicra is a technology made by the ancient Peruvians, which survives today through several other techniques. This method has been implemented at other times since, but it does not use vegetable fiber. It is today being implemented in two ways, one of which is by using gabions.
Gabions are not in the form of bags but are steel mesh filled with stones. It is a similar idea of maintaining enough volume of stones to ensure stability. Until today, shicra technology, with a different name and execution strategy, can be used only on single-story constructions.
There is a possibility that there will be tests on whether the shicra technique will work well with complex constructions with various floors. There might be a need for pairing up the shicra technique with other earthquake-resistant materials such as reinforced polymers, steel and concrete for added benefits. It will be used in complex constructions as well, soon in the near future.
The researchers conducted a shaking test for the shicras with stones on a table to test its response to earthquake vibrations. The results proved that the stones roll during such vibrations, which is the base isolation performance. Thus, it is assumed to perform similarly to the roller base isolation systems.
The solid evidence that the shicra technique works is that the Caral still exists even after 5,000 to 6,000 years. There were several earthquakes around the site within this broad period, but the structures still persist even after dealing with severe tremors.
Top Image: Shicras were a key technology that allowed the Norte Chico to develop a permanent civilization and one of the world’s first cities. Source: I, Xauxa / CC BY 2.5.
By Bipin Dimri
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