Estimación de la anisotropía sísmica en Colombia y su relación con rasgos tectónicos regionales
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Aranguren Canal, Daniel Alfonso
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Abstract
This thesis consists of the estimation of seismic anisotropy parameters (φ, δt) for the
different seismic stations in Colombia, relating the obtained results with the different
regional tectonic features of the northwestern corner of South America. To achieve it,
the polarization of S phases of local events (associated with Nazca-South America and
Caribbean-South America subduction processes) and SKS phases of teleseismic
events is studied. The local events have a depth below 70 km, as well as magnitudes
above or equal to 4.5, while the teleseismic events have hypocentral distances between
90°-130°, and magnitudes above or equal to 6.5. The obtention of seismic anisotropy
parameters (φ, δt) is done for each one of the seismic stations which belong to the
Colombian National Seismological Network, comprising a record time of six consecutive
years (2016-2021). This is done by free-access Python software known as ObsPy and
SplitWavePy. As a result, a mixed control of the anisotropy in the crust is established,
where it prevails a S wave polarization inside the faults rather than a polarization due to
stresses; erratic patterns of φ due to the presence of fluids in the crust are observed;
and orientations of astenospheric flow under the subducting slabs are obtained with a
generalized convergence oriented SW-NE under the NW corner of South America.
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