Open Journal of Earthquake Research, 2018, 7, 269-284 http://www.scirp.org/journal/ojer ISSN Online: 2169-9631 ISSN Print: 2169-9623 DOI: 10.4236/ojer.2018.74014 Nov. 28, 2018 269 Open Journal of Earthquake Research Seasonality and Tectonic Influences on Subduction Zones for Ultra-Deep Earthquakes Marilia Hagen 1 , Anibal Azevedo 2 1 Instituto de Física, Universidade Federal Fluminense, Niterói, Brazil 2 Faculdade de Ciências Aplicadas da Unicamp, Limeira, Brazil Abstract Our previous research has found that deep or very deep earthquakes can be influenced by different seasons of the year. It also indicates that other factors may impact the seasonality in addition to these external parameters. This would explain why the response from Northern Hemisphere and Southern Hemisphere for the seasons is different. In the current research, we will focus on very deep earthquakes over a very long period, 1950-2017, which have high magnitude of M ≥ 6 with depth ≥ 500 km and named ultra-deep earth- quakes (UDQ). We will separate such events by coordinates of each subduc- tion area located in the Pacific Ring of Fire to find which effects the seasons have on these specific areas. Former tomographic studies in such regions pointed out that each area mentioned had systematic differences in the slab configuration along arcs. Our conclusions showed that those discrepancies may influence the enhancement of earthquakes in some seasons or months. Keywords Ultra-Deep Earthquakes (UDQ), Subduction Zones, Tectonics 1. Introduction Our previous works [1] [2] showed that there was a correlation between the sea- sons of the year and the deep or very deep earthquakes. According to those stu- dies, the seasonality of the earthquakes also depends on the location we are searching. The subduction locations examined were displayed by their different coordinates and positions in relation to the globe. We also discussed the impor- tance of dividing into the Northern or Southern Hemispheres, which presented some idiosyncrasies when also calculating by area. How to cite this paper: Hagen, M. and Azevedo, A. (2018) Seasonality and Tec- tonic Influences on Subduction Zones for Ultra-Deep Earthquakes. Open Journal of Earthquake Research, 7, 269-284. https://doi.org/10.4236/ojer.2018.74014 Received: October 25, 2018 Accepted: November 25, 2018 Published: November 28, 2018 Copyright © 2018 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access