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Why the ground shook so far away and for so long

Editorial illustration for “Why the ground shook so far away and for so long”
Illustration éditoriale En Colombie

Updated August 12, 2026 at 11:31 a.m. Colombia time

Distance from the epicentre alone cannot explain what each city felt. Released energy, depth, wave paths and local ground conditions combine.

Subduction: a deep driving force

Along the Pacific coast, the Nazca plate moves beneath the South American plate. Rocks can store stress for long periods before rupturing. The precise mechanism of this event must still be confirmed by the Colombian Geological Survey.

Intermediate depth and wide propagation

An estimated hypocentre near 96 kilometres can spread waves over a broad area. Depth does not remove the danger: magnitude 7.4 represents enormous energy and can damage vulnerable buildings far from the source.

The ground changes the motion

Soft ground and sedimentary basins may amplify some frequencies and prolong shaking. This is known as a site effect. Neighbourhood-level intensity therefore cannot be inferred from magnitude alone.

Between 90 seconds and two minutes recorded near the epicentre

The SGC distinguishes the duration felt by a person, the ground motion recorded by instruments and the duration of motion at the source. For the San José del Palmar earthquake, stations closest to the epicentre recorded about 90 seconds to two minutes of significant motion.

This instrumental range does not mean every witness felt the same duration. Distance from the hypocentre, ground conditions and the building affect perception; softer soils may amplify motion and prolong the sensation of swaying.

Watch the footage on YouTube

These Shorts document damage and search operations in the affected cities.

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