Preliminary Results of the Full-waveform Tomography of South America and Surrounding Oceans using Spectral Elements and Adjoint Methods

In the last years, the ray coverage in the South American continent has greatly improved thanks to the increasing number of seismographic stations. A major contribution came from the recently installed Brazilian Seismographic Network.

On the other hand, more advanced tomographic methods like full-waveform tomography have been developed and are gradually becoming more extensively used due to the exponential growth in computers processing power, allowing for more and more information to be extracted from the seismograms.

In this work, we are using all the available seismographic data acquired in the period of 2011 to 2016 for the South American and surrounding oceans region, including the new data provided by the recently deployed stations to perform a full-waveform tomography in the area. Our goal is that this new velocity model will provide a more accurate and detailed picture of the mantle structures beneath the region, better constraining our geodynamical interpretations.

A total of 161 earthquakes with magnitudes in the range of 6.0-7.0 M_w were found in the Centroid Moment Tensor solutions from the global catalog (Dziewonski, Chou and Woodhouse, 1981; Ekström, Nettles and Dziewonski, 2012). The CMTs were used to model the earthquakes propagation using SPECFEM3D Global software (Komatitsch and Tromp, 2000) with S362wmani, a global S wave velocity model developed by Kustowski et al. (2006) as starting model and 96 events were chosen to be used in the tomography, based on their better initial misfits and ray coverage.

Results of the first iterations will be presented.