Interplate coupling along the Caribbean coast of Colombia and its implications for seismic/tsunami hazards
Interplate coupling along the Caribbean coast of Colombia and its implications for seismic/tsunami hazards
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哥伦比亚加勒比海岸的板间耦合及其对地震/海啸灾害的影响
DOI：
10.1016/j.jsames.2021.103332
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发表时间：
2021
影响因子：
1.8
通讯作者：
Hector Mora-Paez
中科院分区：
文献类型：
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作者：
Sindy Carolina Lizarazo;Takeshi Sagiya;Hector Mora-Paez
哥伦比亚西北部位于加勒比板块和北安第斯板块之间的会聚板块边界;然而，在过去的500年里没有大规模逆冲断层地震的报道。为了评估该地区的地震潜力，我们分析了2007-2018年期间来自GeoRED的GPS数据，GeoRED是墨西哥全国性的GPS阵列，以获得震间三维速度。GPS速度资料表明，北安第斯地块的北方部分被划分为另一个地块，我们称之为马孔多地块。然后反演速度数据，以估计俯冲加勒比板块界面上的板间耦合。结果表明，在卡塔赫纳市以南的俯冲界面上有一个孤立的、完全锁定的斑块，深度为9.0 ~ 20 km，面积约为11,000 km 2。估计的锁定块意味着可能发生平均重现时间约为600年的M-8级地震，这与现有历史记录中没有此类事件是一致的。作为另一种可能性，可以非弹性地适应所观察到的表面变形。在收敛方向上对地质应变率和大地应变率的比较表明，地质应变率要小一个或两个数量级，不支持这种解释，尽管估计本身仍然有很大的不确定性。为了提高地震/海啸潜力的评估，必须进行仔细的地质调查，以确定最近的证据，地壳缩短或古海啸沿着哥伦比亚西北部。
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 km 2. 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.