Explained: What are tetrapods, and did their removal cause ‘unusual vibrations’ along Mumbai’s Marine Drive

Source: The post is based on the article “Explained: What are tetrapods, and did their removal cause ‘unusual vibrations’ along Mumbai’s Marine Drive” published in Indian Express on 22nd July 2022.

What is the News?

In Mumbai, the unusual vibrations (like earthquakes), coinciding with high-tide times, were the result of the relocation of tetrapods as part of the ongoing Coastal Road Project(MCRP).

What are Tetrapods?

Tetra pod in Greek means four-legged. These are four-legged concrete structures that are placed along coastlines to prevent erosion and water damage.

Tetrapods were first used in France in the late 1940s to protect the shore from the sea. Each tetrapod can weigh about two tonnes, sometimes up to 10 tonnes.

What is the importance of Tetrapods?

Each of the Tetrapods’ four legs extends out in a different direction, leaving space in between its legs. This allows the tetrapod to dissipate the force of the incoming waves by making the water flow around and not against it. 

A group of tetrapods also reduces displacement by mutually interlocking. Moreover, their weight and design permit them to battle any weather conditions, and their interlocking, porous barrier dissipates the power of waves and currents.