Análisis 3D de la deformación y cinemática de la Fosa Mesoamericana en la confluencia entre las placas de Rivera y Cocos con las placas Caribe y Norteamericana

Strain 3D analysis and kinematics of the Middle American Trench in the junction of the Rivera and Cocos plates with the North-American and Caribbean plates

Jorge Luis Giner-Robles^1*, Raúl Pérez-López², Javier Elez³, Pablo Silva³, Elvira Roquero⁴,

Adrià Ramos², Carolina Canora¹, Emilio Rodríguez-Escudero¹, Miguel Ángel Rodríguez-Pascua²

¹ Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco s/n, 28049 Madrid, España.

² Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003 Madrid, España.

³ Departamento de Geología, Universidad de Salamanca, Escuela Politécnica Superior de Ávila, Facultad de Ciencias, Hornos Caleros, 50, 05003 Ávila, España.

⁴ Departamento de Edafología. Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, España.

* Autor para correspondencia: (J. L. Giner-Robles) This email address is being protected from spambots. You need JavaScript enabled to view it.

How to cite this article:

Giner-Robles, J.L., Pérez-López, R., Elez, J., Silva, P., Roquero, E., Ramos, A., Canora, C., Rodríguez-Escudero, E., Rodríguez-Pascua, M.A., 2021, Análisis 3D de la deformación y cinemática de la Fosa Mesoamericana en la confluencia entre las placas de Rivera y Cocos con las placas Caribe y Norteamericana: Boletín de la Sociedad Geológica Mexicana, 73 (2), A150121. http://dx.doi.org/10.18268/BSGM2021v73n2a150121

ABSTRACT

In this work, we propose a kinematic model based on the strain 3D spatial distribution from focal mechanism solutions of instrumental earthquakes located along the Middle American Trench, in the convergence zone of Rivera and Cocos plates with North-American and Caribbean tectonic plates. We have used more than 1300 focal mechanisms of earthquakes (M ≥ 5.5), from the Global Centroid-Moment-Tensor (CMT) online global program to perform a cluster analysis of the spatial distribution of the tectonic strain tensor (e_y, e_x, e_z) and its shape (k’). Accordingly, we have applied the Right Dihedral Method to a population of geographically clustered focal mechanisms, as well as the Slip Method, based on the slip data on the theoretical fault plane, for determining the extensional, compressive, and strike-slip zones, in correspondence with the principal tectonic features. Furthermore, we have realized 14 depth profiles across the Middle American Trench (MAT) of the shape of the strain tensor and ternary Kaverina diagrams for constraining the tectonic deformation and developing a 3D model of the kinematics in the region. This analysis depicts a zonation in relation with the changing subduction angle of the slab and an increase of the convergence rate towards the SE, resulting from the mechanical coupling of the subduction, and showing less thrust earthquakes at the Rivera-North American convergence zone than at the Cocos-North American one. The proposed 3D geometry is in good agreement with the spatial distribution of large earthquakes, the slab dip angle, the presence of mantle currents at a 100 km depth and the occurrence of normal-type earthquakes. This model could also account for the presence of anomalous earthquakes such as slow and silent earthquakes in the Guerrero Gap.

Keywords: focal mechanism, Inversion, strain tensor, k’, Mexico.