Colombia Earthquake's Tectonic Origin Differs from Venezuela's, Despite Similar Magnitude

A powerful magnitude 7.4 earthquake struck Colombia on Monday, originating near San José del Palmar in the Chocó department. The seismic event, which occurred at an intermediate depth of 103 kilometers, tragically resulted in at least 132 fatalities and was felt across a wide area of the country.

Viviana Dionisio, a seismologist with Colombia's National Seismological Network, clarified that the earthquake's tectonic origin differs from recent seismic activity in Venezuela, despite both events registering similar magnitudes. The Colombian quake is classified as a "subduction event," occurring when the Nazca Plate slides beneath the South American Plate in the Pacific Ocean. This process builds up energy along the boundary, capable of generating major earthquakes, similar to those historically recorded along the Pacific Ring of Fire.

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It was a tectonic earthquake primarily associated with a subduction mechanism.

"When one tectonic plate is sliding under another, it is called a subduction earthquake. They generally occur on the coasts," Dionisio explained, drawing parallels to significant earthquakes in Chile, Japan, and Ecuador. She contrasted this with the earthquakes in Venezuela, which were linked to a different mechanism.

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When one tectonic plate is sliding under another, it is called a subduction earthquake. They generally occur on the coasts.

In contrast, the seismic events in Venezuela, which caused over 6,300 deaths, resulted from a "strike-slip mechanism" involving the lateral movement between the Caribbean and South American plates. "Venezuela's earthquakes are shallower and have to do with another mechanism, which is a strike-slip mechanism. This is a deeper earthquake, a subduction earthquake," Dionisio emphasized.

Dionisio further elaborated that earthquake depth significantly influences the intensity of damage. Shallower earthquakes release seismic waves closer to the surface, potentially causing more intense shaking near the epicenter. Deeper earthquakes, however, lose energy as their waves travel through more material. Nevertheless, she cautioned that depth alone does not determine damage severity, as building vulnerability and local ground conditions also play crucial roles. Colombia, situated at the confluence of several tectonic plates, faces significant seismic risk.

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Venezuela's earthquakes are shallower and have to do with another mechanism, which is a strike-slip mechanism. This is a deeper earthquake, a subduction earthquake.