Analisis Anomali Geomagnetik Ultra Low Frequency (ULF) Sebagai Prekursor Gempa Bumi Pada Gempa Sumatera 2016

Authors

  • Osi Yusdesra Laboratorium Fisika Bumi, Jurusan Fisika, FMIPA, Universitas Andalas, Kampus Unand, Limau Manis, Padang, 25163., Indonesia
  • Elistia Liza Namigo Laboratorium Fisika Bumi, Jurusan Fisika, FMIPA, Universitas Andalas, Kampus Unand, Limau Manis, Padang, 25163, Indonesia
  • Dian Mega Y BMKG Padang Panjang, Jl. Meteorologi, Silaing Bawah, Padang Panjang Bar, Kota Padang Panjang, 27118, Indonesia

DOI:

https://doi.org/10.25077/jif.10.2.64-72.2018

Abstract

Penelitian tentang anomali sinyal geomagnetik ultra low frequency (ULF) sebagai prekursor gempa telah dilakukan pada 3 gempa besar yang terjadi di Pulau Sumatera tahun 2016. Gempa tersebut adalah gempa Mentawai (Mw=7,8) pada tanggal 2 Maret, gempa Pesisir Selatan (Mw=6,5) pada tanggal 1 Juni dan gempa Pidie Jaya (Mw=6,5) pada tanggal 6 Desember. Penelitian dilakukan dengan menggunakan data geomagnetik yang direkam oleh magnetometer MAGDAS di stasiun pengamatan Gunung Sitoli (GSI), Sumatera Utara. Data geomagnetik yang dianalisis memiliki rentang waktu 2 bulan sebelum kejadian gempa. Data ini diolah pada frekuensi 0,012 Hz. Anomali ditentukan berdasarkan nilai polarisasi power ratio SZ/SH yang melewati batas standar deviasi. Anomali yang terdeteksi kemudian divalidasi dengan data indeks Dst dan indeks Kp. Validasi dilakukan untuk memastikan bahwa anomali merupakan prekursor gempa bumi yang sedang diteliti. Hasil analisis menunjukkan terdapat anomali sinyal eletromagnetikik (ULF) yang terjadi sebelum kejadian gempa bumi. Sebelum kejadian gempa Mentawai terdeteksi 31 anomali, 10 diantaranya dapat dianggap sebagai prekursor gempa. Onset time anomali untuk gempa ini terjadi pada tanggal 19 Februari dengan lead time 12 hari sebelum gempa. Untuk gempa Pesisir Selatan terdeteksi 5 dari 28 anomali yang dapat dijadikan sebagai prekursor gempa dengan onset time pada tanggal 15 Mei dan lead time anomali 17 hari sebelum gempa . Kemudian, terdapat 36 anomali sebelum gempa Pidie Jaya, dimana ada 8 anomali yang dapat dijadikan sebagai prekursor gempa. Gempa ini memiliki onset time yang terjadi pada tanggal 13 November  dan lead time 24 hari sebelum gempa. Dari hasil penelitian dapat disimpulkan bahwa pengamatan prekursor gempa untuk gempa di Sumatera (Mw>6) menggunakan anomali sinyal geomagnetik ULF mempunyai lead time dalam rentang 12-24 hari sebelum gempa terjadi.

 

Kata kunci: prekursor gempa, anomali sinyal geomagnetik, Ultra Low Frequency (ULF),
   MAGDAS, polarisasi power ratio, gempa Sumatera

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Published

2018-10-22

How to Cite

Yusdesra, O., Namigo, E. L., & Mega Y, D. (2018). Analisis Anomali Geomagnetik Ultra Low Frequency (ULF) Sebagai Prekursor Gempa Bumi Pada Gempa Sumatera 2016. JURNAL ILMU FISIKA | UNIVERSITAS ANDALAS, 10(2), 64–72. https://doi.org/10.25077/jif.10.2.64-72.2018

Issue

Vol. 10 No. 2 (2018): September 2018

Section

Research Article

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