Multifractal and monofractal characteristics of ULF magnetic fields in Kachchh region, Gujarat, India: Prospects for earthquake precursor detection

IF 1.8 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Journal of Atmospheric and Solar-Terrestrial Physics Pub Date : 2025-02-19 DOI:10.1016/j.jastp.2025.106478

Sushanta Kumar Sahoo, Madhusudhanarao Katlamudi, Chandra Sekhar Pedapudi

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引用次数: 0

Abstract

Understanding electromagnetic emissions linked to earthquakes is critical for advancing precursor studies, yet research remains limited in seismically active regions like Kachchh, Gujarat, India. This study investigates Ultra-Low Frequency (ULF) magnetic field variations recorded over eight months (January 1–August 13, 2012) at the Multi-parametric Geophysical Observatory (MPGO) in Desalpar (23.742°N, 70.686°E). The analysis focuses on their connection to a magnitude 5.1 earthquake near the observatory on June 20, 2012. Data from a Digital Fluxgate Magnetometer (DFM) were analyzed using Detrended Fluctuation Analysis (DFA) and Multifractal Detrended Fluctuation Analysis (MFDFA) to explore scaling properties in the 0.001–0.1 Hz frequency range. Periodogram analysis identified diurnal and semi-diurnal periodicities, removed using Empirical Mode Decomposition (EMD) to isolate aperiodic signals. DFA results showed non-uniform fluctuation functions with scaling exponent variations prior to the earthquake on June 20, 2012. Notably, the instability index (β) increased in the H-component six days before the event (June 14, 2012), in the D-component on June 17–18, 2012, and in the Z-component one day before (June 19, 2012). MFDFA revealed long-range power-law correlations, with differences in multifractal spectra between observed and shuffled time series, indicating long-range correlations drive multifractality. Surrogate analyses confirmed these correlations while reducing Gaussian characteristics. The multifractal spectrum of H, D, and Z components widened during seismically active phases compared to quiet phases, emphasizing the utility of multifractal analysis in detecting ULF magnetic field instabilities. Abnormal time dynamics in the multifractal characteristics of the H- and Z-components were observed shortly before the earthquake on June 20, 2012. This research highlights the potential of such methods for earthquake monitoring and early-warning systems in active seismic regions.

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来源期刊

Journal of Atmospheric and Solar-Terrestrial Physics 地学-地球化学与地球物理

CiteScore

4.10

自引率

5.30%

发文量

审稿时长

6 months

期刊介绍： The Journal of Atmospheric and Solar-Terrestrial Physics (JASTP) is an international journal concerned with the inter-disciplinary science of the Earth''s atmospheric and space environment, especially the highly varied and highly variable physical phenomena that occur in this natural laboratory and the processes that couple them. The journal covers the physical processes operating in the troposphere, stratosphere, mesosphere, thermosphere, ionosphere, magnetosphere, the Sun, interplanetary medium, and heliosphere. Phenomena occurring in other "spheres", solar influences on climate, and supporting laboratory measurements are also considered. The journal deals especially with the coupling between the different regions. Solar flares, coronal mass ejections, and other energetic events on the Sun create interesting and important perturbations in the near-Earth space environment. The physics of such "space weather" is central to the Journal of Atmospheric and Solar-Terrestrial Physics and the journal welcomes papers that lead in the direction of a predictive understanding of the coupled system. Regarding the upper atmosphere, the subjects of aeronomy, geomagnetism and geoelectricity, auroral phenomena, radio wave propagation, and plasma instabilities, are examples within the broad field of solar-terrestrial physics which emphasise the energy exchange between the solar wind, the magnetospheric and ionospheric plasmas, and the neutral gas. In the lower atmosphere, topics covered range from mesoscale to global scale dynamics, to atmospheric electricity, lightning and its effects, and to anthropogenic changes.