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Abstrak :
Mimika merupakan salah satu daerah di Indonesia tepatnya di Provinsi Papua Tengah yang memiliki potensi pertambangan mineral. Mineral yang tebentuk di di daerah ini merupakan jenis endapan porfiri, dimana mineral emas berasosiasi dengan mineral tembaga (Cu-Au). Keberedaan stuktur yang kompleks pada daerah tersebut menjadi faktor pengontrol terjadinya proses mineralisasi. Pada penelitian ini dilakukan pengolahan data airborne geomagnetic untuk mengidentifikasi keberadaan struktur serta zona mineralisasinya. Data airborne geomagnetic yang sudah di koreksi IGRF dan koreksi harian, ditampilkan dalam Total Magnetic Intensity, yang kemudian dilakukan pemisahan anomali medan magnet regional dan anomali medan magnet residual. Dilakukan juga proses Analytic Signal dan analisis FHD-SVD untuk menentukan keberadaan struktur di daerah tersebut. Didapatkan 4 blok yang menarik dan diidentifikasikan sebagai zona intrusi yaitu blok A, B, C, D. Serta terdapat 3 patahan dengan arah NW-SE yaitu pada patahan SF_1, SF_2, dan SF_3. Selain itu terdapat 2 patahan yang memiliki arah NE-SW, yaitu patahan SF_4 dan SF_5. Hasil pengolahan yang sudah dikorelasikan dengan data geologi, menunjukan bahwa struktur tersebut merupakan pengontrol terjadinya intrusi yang membuat terbentuknya zona mineralisasi. ......Mimika is one of the regions in Indonesia, precisely in Central Papua Province. Mimika has the potential for mineral mining, where the minerals formed in this area are porphyry deposits, where gold minerals are associated with copper minerals (Cu-Au). The existence of complex structures in the area is a controlling factor for the occurrence of the mineralization process. In this study, airborne geomagnetic data processing was carried out to identify the presence of structures and mineralized zones. Airborne geomagnetic data that has been corrected by IGRF and daily corrections are displayed in Total Magnetic Intensity, which is then separated by regional magnetic field anomalies and residual magnetic field anomalies. An Analytic Signal process and FHD-SVD analysis were also carried out to determine the presence of structures in the area. Four interesting blocks were found and identified as intrusion zones, namely blocks A, B, C, D. There were also 3 faults in the NW-SE direction, namely on the SF_1, SF_2, and SF_3 faults. In addition there are 2 faults that have the NE-SW direction, namely the SF_4 and SF_5 faults. Processing results that have been correlated with geological data, show that the structure is a controller of intrusion which causes the formation of mineralized zones.

Abstrak :
Pulau Jawa berada di dekat zona subduksi Lempeng Eurasia dan Indo-Australia, yang menyebabkan terbentuknya patahan-patahan di daratan. Salah satu daerah yang terdampak adalah Kabupaten Sumedang, Jawa Barat. Prediksi gempabumi penting untuk meminimalisir kerusakan. Analisis aktivitas anomali geomagnetik Ultra-low Frequency (ULF) sebelum gempabumi dilakukan di sekitar stasiun geomagnetik TJS Sumedang menggunakan metode Polarization Ratio Analysis (PRA). Metode ini membandingkan nilai medan magnetik komponen vertikal terhadap horizontal (SZ/SG) berbasis Fast Fourier Transform (FFT) untuk mendeteksi anomali geomagnetik ULF (0.01 Hz - 0.04 Hz). Frekuensi ini dipilih karena mudah merambat ke permukaan, memungkinkan deteksi anomali yang jelas. Tiga gempabumi tahun 2020-2021 dengan magnitudo (M) ≥ 5 dan jarak episenter (R) ≤ 150 km (10 Maret 2020, M5; 25 Oktober 2020, M5.4; dan 27 April 2021, M5) dianalisis. Data geomagnetik malam hari komponen X, Y, dan Z dipilih untuk mengurangi noise. Hasil menunjukkan frekuensi 0.01 Hz - 0.04 Hz optimal mendeteksi prekursor gempa pada 27 April 2021. Anomali geomagnetik ULF tidak berkaitan dengan badai geomagnetik, dibuktikan dengan nilai indeks Dst (Disturbance storm time) yang tidak melebihi ambang batas. ......Java Island is adjacent to the subduction zone of the Eurasian and Indo-Australian Plates, causing the formation of several faults on land. From the formation of faults that can be caused by earthquakes, there are areas that are affected, one of which is Sumedang Regency, West Java. Earthquake prediction efforts are very important to minimize the damage that will occur. Ultra-low Frequency (ULF) geomagnetic anomaly activity was analyzed before the earthquake around the TJS Sumedang geomagnetic station using the Polarization Ratio Analysis (PRA) method, which compares the magnetic field value of the vertical component to the horizontal component (SZ/SG) based on Fast Fourier Transform (FFT), which is used to convert data from the time domain into the frequency domain to see ULF scale geomagnetic anomaly activity from 0.01 Hz - 0.04 Hz because this frequency wave easily propagates to the surface, allowing clear anomaly detection. Three earthquakes in 2020-2021 taken at magnitude (M) ≥ 5 and earthquake epicenter (R) ≤ 150 km (EQ1 with M5 on March 10, 2020, EQ2 with M5.4 on October 25, 2020, and EQ3 with M5 on April 27, 2021) in the vicinity of the TJS Sumedang geomagnetic station were selected because the larger the M and the closer the R of the earthquake can strengthen the geomagnetic anomaly readings. Nighttime geomagnetic data of X, Y, and Z components were selected to reduce noise or human activity. The results showed that the frequency of 0.01 Hz - 0.04 Hz was optimal for detecting possible precursors of the M5 earthquake on April 27, 2021 (EQ1), and the ULF geomagnetic anomaly in this study was not related to geomagnetic storms, which was obtained from the Dst (Disturbance storm time) index value which did not exceed the threshold line.