厄瓜多尔俯冲区震间闭锁与粘弹性变形研究

Study on Interseismic Locking and Viscoelastic Deformation in the Ecuador Subduction Zone

以厄瓜多尔俯冲区为例,建立区域三维纯弹性和粘弹性模型,并基于有限元数值模拟方法分析其震间变形过程,同时以十余年的震间GPS速度场为约束,估算不同模型下的最佳震间闭锁深度。结果表明,在厄瓜多尔俯冲区,基于弹性模型的最佳震间闭锁深度约为30~35 km,而基于粘弹性模型的最佳闭锁深度为25 km。同时,相比于弹性模型,粘弹性模型能够更好地解释震间地表变形,说明该区域深部粘弹性圈层在俯冲板块的推挤作用下会引起较为明显的上地壳变形。

Taking the Ecuador subduction zone as an example,we establish a three-dimensional pure elastic and viscoelastic model of the area,and analyze the interseismic deformation based on the numerical simulation method.We estimate the optimal interseismic locking depth under different models using the interseismic GPS velocity field for more than 10 years as constraint.The results show that in the Ecuador subduction zone,the optimal interseismic locking depth based on the elastic model is about 30 to 35 km,while the optimal locking depth based on the viscoelastic model is 25 km.At the same time,compared with the elastic model,the viscoelastic model can better explain the interseismic surface deformation,indicating that in this area,the deep viscoelastic lithosphere will cause obvious upper crustal deformation under the pushing action of the subducting slabs.