The image was created using observations from the Sentinel-1 satellites, which are part of the European Copernicus programme. These satellites do not take traditional photographs; Instead, they use their radar to “illuminate” the Earth’s surface and record the time it takes for the signal to return to the sensor. By comparing two measurements of the same location taken on different dates, scientists can determine if the ground has shifted, even if the change is too small to be seen with the naked eye.
To create the map, scientists compared an observation taken on June 18, a week before the earthquake, with another observation taken on June 25, the day after the pair of earthquakes, which were magnitudes 7.2 and 7.5, respectively. This comparison allowed them to construct what is known as an interferogram, which shows how much the ground was deformed after the event.
ESA explains that what stands out in the map are the repeating colored bars that form horizontal lines in the north. Each complete repetition of the sequence – blue, green, yellow, red and blue again – represents a fixed increase in the change in distance between the satellite and the ground. The more complete cycles seen between one area and another, the greater the cumulative ground displacement.
The pattern of bands seen in the northern part of the map matches the area of the earthquake’s epicenter, where the main deformation also occurred. The bands roughly follow the path of the San Sebastian Fault System, one of the main tectonic structures in northern Venezuela. ESA estimates that displacement in the area was on the order of 30 centimeters (12 in).
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