Abstract

LAROCCA, P.; ARECCO, M. A.  and  MORA, M.. Wavelet-based Characterization of Seismicity and Geomagnetic Disturbances in the South Sandwich Microplate Area. Geofís. Intl [online]. 2021, vol.60, n.4, pp.320-332.  Epub Jan 31, 2022. ISSN 2954-436X.  https://doi.org/10.22201/igeof.00167169p.2021.60.4.2119.

This paper analyzes geomagnetic disturbances associated with seismic events in the northern transcurrent margin of the South Sandwich microplate and South American plate, with their epicenter at distances within 350 km from King Edward Point geomagnetic observatory on the archipelago of the Georgias del Sur islands.

Geomagnetic field records measured over a one-year period in three observatories of the INTERMAGNET network near the area under study are examined. Anomalous variations in geomagnetic records can be detected within approximately 3 hours before the manifestation of seismic events with a magnitude above 4.4 Mw.

Based on the analysis of the differences in horizontal field components among the observatories and the frequency spectrum of the geomagnetic field observations using the wavelet method, oscillations of several nT can be observed before an event' in addition to magnetic peaks with variable amplitude and duration.

It is worth noting that, during the period of study, no severe geomagnetic storms were recorded as this was a phase of low solar activity (solar cycle 24 minimum).

The observation of these potential magnetic precursors suggests that there is a critical preparatory period in a region with geological faults related to the stress generated in the rocks before the built-up energy is released in the hypocenter area, within the lithosphere, which may possibly predict the mechanical motion based on anomalous geomagnetic records.

Keywords : geomagnetic variations; earthquakes; geomagnetic activity indices.