Analisis Tensor Fase dan Pemodelan 2D Data Magnetotellurik
(Studi Kasus Lapangan Panas Bumi Mountain Home, Idaho, USA)
Keywords
Dimensionalitas, Magnetotellurik, Panas Bumi, Tensor FaseAbstract
Salah satu metode geofisika untuk mengetahui bawah permukaan bumi adalah metode magnetotellurik yang memanfaatkan sumber alami berupa medan magnet bumi dari medan listrik dan variasi medan magnet. Namun, data yang diperoleh dari lapangan masih dipengaruhi oleh noise atau distorsi yang akan menutupi dimensionalitas sebenarnya dari struktur bawah permukaan, sehingga dapat mengakibatkan kesalahan dalam melakukan interpretasi. Oleh karena itu perlu dilakukan analisis tensor fase untuk mengidentifikasi struktur bawah permukaan yang tidak dipengaruhi distorsi galvanik. Berdasarkan hasil yang diperoleh daerah penelitian memiliki dimensionalitas 2D dengan arah geo-electrical strike N1750E berarah Utara Barat Laut hingga Tenggara. Hasil inversi 2D menunjukkan bahwa resistivitas rendah 1-10 Ωm diidentifikasi sebagai zona alterasi atau clay cap yang berupa batuan sedimen yang berada kedalaman ~1.5 km dimana zona alterasi ini memiliki kemenerusan ke arah timur laut. Pada resistivitas 200-500 Ωm diidentifikasikan sebagai basal berpori. Pada resistivitas 50-70 Ωm diidentifikasikan sebagai riolit yang berasosiasi dengan fluida geotermal.
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