3-D structure of colombia from 1-D constrained joint inversion of receiver functions and surface wave dispersion.

摘要

The country, Colombia, resides at the northwest corner of the South America with seismicity and volcanism due to the intersections of the Nazca, South America and Caribbean tectonic plates (Figure 1). The boundaries of the South America plate, on which Colombia lies, borders between 60 to 200 kilometers from its coasts. A dense spot of seismicity known as the Bucaramanga Nest has had many theories to explain its existence. Two tectonic microplates suspected in this region have not been well understood. With many mysteries of the behavior of the tectonic plates beneath Colombia, using new methods may shed light on some of these controversies.;We need to generate models of the crust and mantle to examine these plates. To make that model, we can calculate 1-D joint inversion models that combine receiver functions and surface wave dispersion tomography which will be useful in this application due to their complementary ability to study velocities. A new method to calculate receiver functions by adjusting back azimuth rotations will be used.;Not many 3-D models that can be directly compared to our data so asserting the correctness of the geologic analysis would be difficult. Other studies of Colombia have focused on this region in much different scales and areas without much exactness on their depths and locales. Using our data sets and techniques, we believe our data to have some consistencies with recent and past models of Colombia. Notable features we found in this research that can be comparable to others would be the presence of plates in the upper mantle at appropriate depths.;We believed to have seen the major plates beneath the North Andes plate. At about 60 km depth across the North Andes -- South America plate boundary, we see a very shallow subduction that continues for a few hundred kilometers. We believe to have seen the deep slabs that are causing the Bucaramanga Nest seismicity that had been studied in Zarifi et Al (2007). The Nazca plate can be below at our western stations. Along the subduction zone of the Caribbean plate beneath the North Andes plate, we saw steep subduction.