Analysis of geomagnetic field and atmospheric pressure anomalies associated with seismic activity on the Scotia plates and Sandwich

• Main Authors: Arecco, María Alejandra, Larocca, Patricia A., Otero, Lidia A., Mora, Mariana C., Canero, María Florencia
• Format: Article in Journal/Newspaper
• Language: Spanish
• Published: Asociación Argentina de Geofísicos y Geodestas 2022
• Subjects: actividad geomagnética; variación de presión atmosférica; sismos; placas Scotia y Sandwich; geomagnetic activity; atmospheric pressure; earthquakes; scotia plate; Argentino; Argentina; Merra; Orcadas; King Edward Point; antartic*; South Atlantic Ocean
• Online Access: https://revistas.unlp.edu.ar/geoacta/article/view/14495

Geomagnetic field and atmospheric pressure disturbances are analyzed on this work, related to seismic events. These are located on the Scotia and Sandwich plate-margins in the South Atlantic Ocean. Near the epicenters are placed the INTERMAGNET geomagnetic observatories: King Edward Point (KEP) on the South Georgia’ islands, Orcadas (ORC) on Orcadas’ islands, Argentina Island (AIA) on Antartica and Puerto Argentino (PST) on Malvinas Islands. Geomagnetic field records from the observatories are studied during the previous twenty four hours of the seismic event. As the horizontal geomagnetic component is the most sensitive one to these changes, results in the magnitude selected for the analysis. To avoid the diurnal variation effects on the geomagnetic data, the differences between the horizontal components of two observatories are calculated. It is important to remark that on the period of study severe geomagnetic storms are not registered due to a low Sun activity phase. Analyzing the mentioned differences with the wavelets method it is possible to observe ranges of high energy up to very high frequencies previous to the event; in addition to ± 2 nT magnetic peaks of amplitude on the oscillations and a variable duration when applied a low-pass filter. It is possible to detect abnormal variations on an interval of approximately 3 hours before seismic events for Mw ≥ 6.6. On the other hand, atmospheric pressure grids at the sea level global are analyzed, selected on the seism zone, on periods of two to four hours previous to the event, showing distinctive low and high pressure zones. The data is obtained from the MERRA-2 base. The temporal series makes evident a pressure local minimum few hours before the event due to the sea surface ascent/descent. En este trabajo se analizan perturbaciones del campo magnético terrestre y presión atmosférica a nivel del mar relacionadas con eventos sísmicos. Los mismos están localizados en los márgenes de las placas Scotia y Sándwich, en el Atlántico Sur. Los observatorios ...