Penentuan Filtering Frekuensi pada Processing Waveform Gempa dalam Menentukan Best Fit Kurva Waveform dengan Data Synthetic dan Solusi Momen Tensor Study Kasus Sequence Lombok pada Tanggal 28 Juli 2018-19 Agustus 2018

Abstract

Research Determination of frequency, variance reduction and fault pattern can be done in the Lombok earthquake in 2018 with magnitude 5.9 MW to 6.9 MW using the ISOLA-GUI program. The principle of this program is to process three components of seismic waves recorded in seismograms. Data in the waveform are processed according to each earthquake event that occurs and the calculation of the Green function and inversion are used. In the inversion stage, 4 filters are used f1, f2, f3, f4 which are filled to obtain the appropriate variance reduction value. Plotting for results is done after the inversion stage and the variance reduction value is obtained which is close to precision 1. The next plot is the moment tensor value along with the fracture plane pattern symbolized by beachball. Processing is carried out at all earthquake events. After calculation, processing and interpretation, the value of the variance reduction and frequency obtained is Event 2018-07-28 22:47:38 obtained by the frequency of 0.022-0.028; 0.032-0.037, variance reduction 0.84. Event 2018-08-05 11:46:34 obtained the frequency of 0.027-0,032; 0.033-0,038, variance reduction 0.71. Event 2018-08-09 05:25:32 the frequency is 0.022-0.028; 0.032-0,037, Variance reduction 0.85. Event 2018-08-19 04:10:22 obtained a frequency of 0.022-0,026; 0.03-0,034 Variance reduction 0.8. Event 2018-08-19 14:56:26 obtained a frequency of 0.023-0,028; 0.032-0,037 Variance reduction 0.67.

Penelitian Penentuan frekuensi, varian reduction dan pola bidang patahan dapat dilakukan pada gempa bumi Lombok pada tahun 2018 dengan magnitude 5.9 Mw sampai 6.9Mw menggunakan program ISOLA-GUI. Prinsip program ini mengolah tiga komponen gelombang seismik yang terekam dalam seismogram. Data berupa gelombang diolah sesuai masing-masing event gempa yang terjadi dan digunakan perhitungan fungsi Green serta inversi. Pada tahap inversi digunakan 4 filter f1, f2, f3, f4 yang diisi untuk memperoleh nilai varian reduction yang tepat. Plotting untuk hasil dilakukan setelah tahap inversi dan didapatkan nilai variance reduction yang bernilai mendekati presisi1. Plot selanjutnya berupa nilai momen tensor beserta pola bidang patahan yang disimbolkan dengan beachball. Pengolahan tersebut dilakukan pada seluruh event gempa. Setelah perhitungan, pengolahan, dan interpretasi, maka nilai varian reduction dan Frekuensi yang didapatkan yaitu Event 2018-07-28 22:47:38 diperoleh frekuensi 0.022-0.028; 0.032-0.037 , varian reduction 0.84. Event 2018-08-05 11:46:34 diperoleh frekuensi 0.027-0.032; 0.033-0.038, varian reduction 0.71. Event 2018-08-09 05:25:32 diperoleh frekuesi 0.022-0.028; 0.032-0.037, Varian reduction 0.85. Event 2018-08-19 04:10:22 diperoleh frekuesi 0.022-0.026; 0.03-0.034 Varian reduction 0.8. Event 2018-08-19 14:56:26 diperoleh frekuesi 0.023-0.028 ; 0.032-0.037 Varian reduction 0.67.