Tectonic Shifts under Colombian territories

Two weeks ago, on August 17th, we experienced a strong ground shake around noon in Bogota. It had a magnitude of 6.3 and a sever intensity (MMI) that lasted for about 3 minutes. At our apartment, books, pictures and other objects fell from shelves and walls, water from the toilets overflowed, and blinds and doors swung. I was sitting working on a computer, near a window, and few seconds after the violent shaking started I stood up and walked towards the living room and told Inara and Cony, who were having lunch, that we needed to locate under the dining table. It is an earthquake? Yes, it is. The quake was intense. After the initial sudden large jolt, a strong shaking lasted for several minutes. MJ and Teresita, who were also at the apartment, joined us under the dining table, and we waited until the earthquake passed. When it stopped, we thought about exiting the building, and talked about how to do it safely, until another quake occurred, this time at a 5.6 magnitud, and for a shorter period of time. While listening sirens and alarms nearby we exited the building using the stairs and met with other neighbors on the street. Lots of people were there, surprised, scared, talking to each other, calling and sending messages with their phones on their hands.

This was the first strong earthquake I have experienced with a strong intensity in my life. My perception of it, and of the replicas that followed during the day, let me in a state of post-earthquake stress for several days. During the past weeks I have been dealing with post-earthquake dizziness, a feeling of disturbance in the equilibrium that is known a an “earthquake hangover.” Such feeling has triggered my curiosity about the power of seismic waves generated by planet Earth’s tectonic shifts, their scale, and how they can literally move the ground of complete populations and communities. Our planet is dynamic, in constant change, and the major and minor tectonic plates that make up the Earth’s crust are always moving. The movements of these plates are driven by the convective currents in the underlying semi-fluid asthenosphere, where heat generated from the Earth’s interior causes the lithospheric plates to drift, collide, pull apart, or slide past one another. Tectonic shifts are not only responsible for the ever-changing landscapes on our planet but also play a crucial role in the distribution of continents, the formation of oceans, and the geological events that have shaped the history of our planet over millions of years.

And yet it moves. The Earth’s surface is active and move us, all the time. Always interacting and shifting, the motion of tectonic plates reshapes the planet’s rigid outer shell. This movement produces not only earthquakes, but also volcanoes and mountains ranges. In northern South America, where the territory of Colombia is located, seismic activity is high. This territory is located atop a restless intersection of tectonic plates: the Pacific Ocean’s Nazca Plate, the Caribbean plate, and the South American plate. Such interaction has made several geological faults, and has defined a particular geography full of topographic diversity and accidents. The split of the Andean Cordillera in three ranges, and the high plain of Bogota (altiplano) in the eastern the Eastern Cordillera are examples of such dramatic and voluptuous topography.

Moreover, it creates many earthquakes. There are thousands of quakes in Colombia every year, particularly in the areas of the central, eastern and western Andean mountain ranges, and the Pacific coast. I have been checking the online seismic viewer from the Servicio Geologico Colombiano (SGC) who monitors the earthquake activity in the country, and it is impressive to see the amount of shakes that take place every day under Colombian territory.

SGC online seismic activity viewer. Data from August 27, 2023.

Despite the perplexing earthquake activity in Colombia, there is little knowledge among the population about how to act during and after a quake. The Servicio Geologico Colombiano (SGC) has been doing a great job on social media, answering the several questions that emerged after the past August earthquake. Since this shake was strongly felt by many people in Bogota, the country’s capital, the event and its consequences got a lot of attention by the national media. Below is a Twitter/X threat from the SGC that communicates knowledge to a broad audience, explaining the causes, providing tips on how to react, and what to expect during and after an earthquake.

https://twitter.com/sgcol/status/1692530917900743154?s=20

This kind of open science communication is useful, and helps people to navigate the anxieties and stresses that emerge during and after the tectonic shifts. It should be developed not only as a reaction, but also as a proactive strategy to build knowledge and prevent crisis situations.

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