GPS data reveal possible earthquake, tsunami hazard in northwestern Colombia

GPS data reveal possible earthquake, tsunami hazard in northwestern Colombia

Data from a GPS network in Colombia have revealed a shallow and completely closed portion of the Caribbean subduction zone in the country suggesting a potentially large earthquake and tsunami risk for the northwestern region.

The lock patch located south of the city of Cartagena is capable of generating an earthquake of 8.0 magnitude every 600 years, said Sindhi Lizarazo of Nagoya University in Japan, who presented the study at the 2021 annual meeting of the Seismological Society of America (SSA).

Colombia lies in the middle of a complex tectonic zone, where Caribbean, Nazca and South American tectonic plates and other small tectonic blocks converge. The Caribbean plate is converging very slowly along the northern part of Colombia – moving at 7 millimeters per year – which in part may be the reason for the long stay in Northwest Columbia between major earthquakes.

“The only historical record of a recent devastating [magnitude 6.4] earthquake in the Colombian Caribbean region was close to Santa Marta on May 22, 1834,” Lizarazzo said. “However, there is no seismic event that meets the magnitude estimated by our study, nor the tsunami in the historical record on the northern part of Colombia.”

To better understand the complex movements and crustal deformations that are taking place in the area, Lizrazzo and his colleagues analyzed data from a nationwide GPS network known as GEOdesia: Red de Estudios de Deformación in Spanish. The network has been operated by the Geological Survey of Columbia since 2007 and has 150 permanent stations in continuous operation.

GPS data can be used to estimate the movements and crustal deformation of tectonic plates interacting against each other.

The data analyzed by Lizrazzo and his colleagues traced the motion of the northern part of the North Andean Block – a “microplate” squeezed between the Nazca and South American plates – causing it to interact with the overlying Caribbean plate.

Using these data with realistic slab configurations, the researchers hypothesized that there is a limit and degree of interplate locking along this range, where stress can build up without releasing in an earthquake.

“The study provides the first evidence of a shallow closed area south of Cartagena,” Lizarazzo said. “This indicates that this stretch of the Caribbean – South America plate boundary in northwestern Colombia may be the location of significant earthquake and tsunami hazards.”

To fully evaluate the potential of this threat, researchers need to conduct large-scale geological mapping, and look for evidence of past tsunamis and major earthquakes in the region, among other studies.

“It is also necessary to continue with the density of GPS networks in the country, increasing its coverage and operations in real time,” Lizarazzo said.

The lock patch located south of the city of Cartagena is capable of generating an earthquake of 8.0 magnitude every 600 years, said Sindhi Lizrazo of Nagoya University in Japan, who presented the study at the 2021 annual meeting of the Seismological Society of America (SSA).

Colombia lies in the middle of a complex tectonic zone, where Caribbean, Nazca and South American tectonic plates and other small tectonic blocks converge. The Caribbean plate is converging very slowly along the northern part of Colombia – moving at 7 millimeters per year – which in part may be the reason for the long stay in Northwest Columbia between major earthquakes.

“The only historical record of a recent devastating [magnitude 6.4] earthquake in the Colombian Caribbean region was close to Santa Marta on May 22, 1834,” Lizarazzo said.

“However, there is no seismic event that meets the magnitude estimated by our study, nor the tsunami in the historical record over the northern part of Colombia.”

To better understand the complex movements and crustal deformations that are taking place in the area, Lizrazzo and his colleagues analyzed data from a nationwide GPS network known as GEOdesia: Red de Estudios de Deformación in Spanish.

The network has been operated by the Geological Survey of Columbia since 2007 and has 150 permanent stations in continuous operation.

GPS data can be used to estimate the movements and crustal deformation of tectonic plates interacting against each other.

The data analyzed by Lizrazzo and his colleagues traced the motion of the northern part of the North Andean Block — a “microplate” squeezed between the Nazca and South American plates — causing it to interact with the overlying Caribbean plate.

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