Scaling characteristics in ultra low frequency magnetotelluric signals: Investigating of possible earthquake precursors, northern Algeria
In the recent decade, earthquake-related electromagnetic phenomena have been considered one of the most promising candidates to achieve short-term earthquake prediction. Magnetotelluric measurements still remain one of the most challenging and debated questions in the scientific community regarding short-term earthquake prediction. Since 2018, a continuous recording magnetotelluric station has been installed at the Medea Observatory (Northern Algeria), whose main role is the assessment of seismo-electromagnetic signals. Using an MTU-A Phoenix system, we measure the five components of the telluric and magnetic fields. Multifractal detrended fluctuation analysis is a powerful method for capturing scaling behavior in non-stationary time series. Using an appropriate instability index, it is possible to identify and quantify deviations from uniform power-law scaling, which suggest the presence of changing dynamics in the system under study. In this context, the calculated scaling instability index β (defined as the range of the local scaling exponents) of magnetotelluric time series (in the frequency range below 1 Hz) were investigated. We considered only those seismic events that satisfy the Dobrovolsky rule (r=100.43M). Several significant scaling behaviors in the magnetotelluric temporal fluctuations were revealed, which could be linked with the occurrence of earthquakes in the northern part of Algeria, such as the 2021 Bejaïa earthquake (M = 6, epicentral distance 235 km) and the 2020 Blida earthquake (M = 4.5, epicentral distance 18 km). These results prove to be powerful for short-term earthquake prediction.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)