Original scientific paper

https://doi.org/10.17794/rgn.2024.1.6

ASSESSMENT OF ULTRA-LOW FREQUENCY (ULF) GEOMAGNETIC PHENOMENA ASSOCIATED WITH EARTHQUAKES IN THE WESTERN PART OF JAVA ISLAND, INDONESIA DURING 2020

Cinantya Nirmala Dewi orcid.org/0000-0003-1327-2286 ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia *
Febty Febriani orcid.org/0000-0002-0232-1559 ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Titi Anggono orcid.org/0000-0003-1210-6972 ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Syuhada Syuhada ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Mohamad Ramdhan ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Mohammad Hasib orcid.org/0000-0002-3560-4547 ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Aditya Dwi Prasetio ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Hendra Suwarta Suprihatin ; Indonesian Agency for Meteorological, Climatological, and Geophysical (BMKG), Jl.Angkasa I No.2 Kemayoran, Jakarta Pusat 10610, Indonesia
Suaidi Ahadi ; Indonesian Agency for Meteorological, Climatological, and Geophysical (BMKG), Jl.Angkasa I No.2 Kemayoran, Jakarta Pusat 10610, Indonesia
Mohammad Nafian ; Physics Department, Syarif Hidayatullah State Islamic University, Jl.Lkr Kampus UIN Ciputat Timur, Tangerang Selatan 15412, Indonesia
Suwondo Suwondo orcid.org/0009-0005-9329-5737 ; Physics Department, Syarif Hidayatullah State Islamic University, Jl.Lkr Kampus UIN Ciputat Timur, Tangerang Selatan 15412, Indonesia
Faiz Muttaqy ; Research Center for Geological Disaster, National Research and Innovation Agency (BRIN), Jl.Sangkuriang Dago, Bandung 40135, Indonesia
Muhamad Syirojudin ; Indonesian Agency for Meteorological, Climatological, and Geophysical (BMKG), Jl.Angkasa I No.2 Kemayoran, Jakarta Pusat 10610, Indonesia
Hasanudin Hasanudin ; Indonesian Agency for Meteorological, Climatological, and Geophysical (BMKG), Jl.Angkasa I No.2 Kemayoran, Jakarta Pusat 10610, Indonesia
Indah Marsyam ; Indonesian Agency for Meteorological, Climatological, and Geophysical (BMKG), Jl.Angkasa I No.2 Kemayoran, Jakarta Pusat 10610, Indonesia

* Corresponding author.

Abstract

Ultra-low frequency (ULF) geomagnetic analysis is a robust method for earthquake (EQ) forecasting. We conducted a simultaneous study of EQ precursors around the western part of Java Island in 2020 using wavelet transform (WT) and detrended fluctuation analysis (DFA) methods. ULF geomagnetic data (March to December 2020, 16:00–21:00 UTC or 23.00–04.00 LT) from Lampung Selatan (LPS) geomagnetic station were used to assess the precursors. We analyzed four EQs with an epicenter distance (R) of around 100 km from LPS station and a magnitude (M) greater than 5 Mw. We analyzed changes in the SZ/SG values and α values from the WT and DFA analyses against the threshold (µ±2σ) to identify anomalies related to the EQs. The result showed that SZ/SG anomalies occurred simultaneously with a decrease in α values several weeks prior to probable source EQ when there was a very low geomagnetic activity (Dst ≤ -30 nT). The Mw5.4 (07/07/2020) EQ might be the main source that led to the appearance of the precursor since it had the highest magnitude and KLS values compared to others. The combined WT and DFA results showed anomalies 1.5–13 weeks before the Mw5.4 (07/07/2020) EQ. The results suggest that WT and DFA are suitable methods for detecting EQ precursors but more work is needed to link the precursors to specific EQs.

Keywords

earthquake precursor; ULF emission; wavelet transform analysis; detrended fluctuation analysis

Hrčak ID:

314919

URI

https://hrcak.srce.hr/314919

Publication date:

1.3.2024.

Article data in other languages: croatian

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