Northwestern Colombia is located at a convergent plate boundary between the Caribbean plate and the North Andean Block; however, no megathrust earthquakes have been reported during last 500 years. In order to evaluate seismic potential in this area, we analyze GPS data during 2007–2018 from GeoRED – the nationwide GPS array in Colombia – to obtain interseismic 3-dimensional velocities. GPS velocity data indicate the northern part of the North Andean Block is differentiated as another block and we name it Macondo Block. The velocity data are then inverted to estimate interplate coupling on the subducting Caribbean plate interface. The result shows an isolated, fully locked patch south of the city of Cartagena extending from 9.0 to 20 km in depth on the subduction interface with an area of $~$11,000 km². The estimated locked patch implies a potential of M-8 class earthquake with an average recurrence time of ~600 years, which is consistent with the absence of such an event in the available historical record. As another possibility, the observed surface deformation may be accommodated inelastically. A comparison of geological and geodetic strain rates in the convergence direction shows that the geological one is smaller by one or two orders of magnitude and does not support such an interpretation though the estimate itself still has a large uncertainty. For improving the evaluation of earthquake/tsunami potential, it is essential to conduct a careful geological investigation to identify recent evidence of crustal shortening or paleotsunami along northwestern Colombia.

哥伦比亚西北部位于加勒比板块与北安第斯山脉之间的板块交汇处。然而，在过去的500年中，没有大地震的报道。为了评估该地区的地震潜力，我们分析了哥伦比亚全国性GPS阵列GeoRED在2007–2018年期间的GPS数据，以获得地震3维速度。GPS速度数据表明，北安第斯区块的北部被区分为另一个区块，我们将其命名为Macondo区块。然后将速度数据反转，以估算俯冲加勒比板块界面上的板间耦合。结果显示，在卡塔赫纳市以南，一个俯冲界面上深度为9.0至20 km的孤立，完全锁定的斑块，面积为$〜$11,000千米²。估计的锁定斑块暗示可能发生M-8级地震，平均复发时间约为600年，这与可用历史记录中未发生此类事件是一致的。作为另一种可能性，可以无弹性地适应观察到的表面变形。在收敛方向上对地质应变率和大地应变率的比较表明，尽管估算本身仍具有很大的不确定性，但地质应变率要小一个或两个数量级，因此不支持这种解释。为了改进对地震/海啸潜力的评估，必须进行仔细的地质调查，以找出哥伦比亚西北部地壳缩短或古海啸的最新证据。