Resumen:
Subduction of the Nazca oceanic plate under the South American plate and the obliquity
of this subduction has generated the NE movement of the Astilla Norandina (NAS) whose
eastern limit in Ecuador is the Chingual-Cosanga-Pallatanga-Puná mega- fault (CCPP).
The CCPP is a strike-slip fault system and its segments represent some of the most active
intra-continental seismic structures in Ecuador. This study provides thefirst tomographic
images of the cortex along the CCPP to contribute to the characterization of its
geometry. In order to achieve this objective, seismic data, seismic
wave velocity models, topographic and geological maps were used. The geometric
characteristics of the fault segments were obtained by travel-time tomography.
Tomography of the Puná and Chingual segments shows almost vertical dipping angles.
The southern section of Pallatanga shows a dipping angle of 75 ° oriented to the west
and increases to a near vertical dip to the north. The Cosanga segment isthe only reverse
segment of the CCPP. The convergence of two faults that make up this segment could
be related to the superficial landslide of the Bermejo River. The Chingual segment
advances N-NE and marks the separation between sedimentary and metamorphic
lithologies. This investigation presents images of the crust in depth for the CCPP mega fault and the associations with the lithology of its segments to offer a complete
interpretation of the geometry and seismicity of this fault system.
