Detection of ULF Geomagnetic Anomalies Associated to Seismic Activity Using EMD Method and Fractal Dimension Theory

Over the past few years, analysis of anomalies associated to seismic activity in ultra-low frequency (ULF) geomagnetic signals has been the task of many researchers around the world. For the analysis, classical and recent signal processing techniques have been used; yet, despite obtaining promising results, the development and application of new techniques and methodologies that offer suitable and reliable results in terms of complexity and performance are still open issues due to the inherent relevance of this topic for human being. In this work, the analysis of ULF geomagnetic signals using empirical mode decomposition (EMD) method and fractal dimension (FD) theory is carried out. The signals have been obtained at the Juriquilla station, which is localized in Queretaro, Mexico (geographic coordinates: longitude 100.45° E and latitude 20.70° N). First, EMD method is applied as a pre-processing technique, where the goals are to remove background noise and highlight non-visible frequency components. Then, three FD algorithms named Katz, Higuchi, and Box are applied in a separated way in order to assess which algorithm provides more information related to anomalies into the ULF signal. The obtained results show that the EMD-FD-based analysis is a suitable tool to detect geomagnetic anomalies related with seismic activity