ANALISIS DEFORMASI DAERAH PORONG â SIDOARJO TERKAIT SEMBURAN LUMPUR DENGAN TEKNIK INTERFEROMETRI - Agustan, Agustan; Kimata, Fumiaki (MAJALAH ILMIAH GLOBE, 2011)
Semburan lumpur di daerah Sidoarjo, Jawa Timur telah mengakibatkan deformasi lahan. Penelitian ini dilakukan untuk mengkaji kemampuan citra satelit radar dengan teknik interferometri untuk menganalisis deformasi lahan tersebut. Data satelit radar (ALOSPALSAR) dari bulan Agustus 2007 sampai Januari 2009 diolah menggunakan 2-pass differential InSAR. Interferogram dibentuk dari dua data radar dengan ketelitian registrasi offset kurang dari setengah pixel dengan pendekatan polinomial orde tiga. Simulasi data DEM diturunkan dari data SRTM, dan beda fase hasil perhitungan dipertajam dengan menggunakan algoritma Median Spatial Filter. Hasil penelitian menunjukkan bahwa sejak periode awal, daerah terdeformasi telah teridentifikasi. Peningkatan besaran vertikal lebih dominan dibandingkan peningkatan luasnya daerah terdeformasi dan mengilustrasikan penurunan permukaan tanah (land subsidence) di beberapa tempat. Peningkatan permukaan tanah juga teridentifikasi tetapi hal ini mungkin terkait dengan aktifitas peninggian tanggul penahan luapan lumpur. Penurunan permukaan tanah terdeteksi dari 5 â 16 cm dalam 17 bulan. Mekanisme perubahan permukaan dapat dimodelkan berdasarkanpola warna yang terdeteksi dengan pendekatan patahan dan intrusi.Kata Kunci : InSAR, Interferometri Deferensial, Semburan Lumpur, Deformasi LahanABSTRACTThe mud flow in Sidorajo, East Java has caused land deformation. This research focused on assessing the ability of differential InSAR to detect the land deformation related to the mud volcano. Seven ALOS-PALSAR data, which were obtained on August 2007 until January 2009 were processed based on 2-pass differential InSAR. The deformation were enhanced on the image using Median Spatial Filtering technique. It is shown that the deformed areas have expanded to the north as uplifted area and to the west as subsided area. The deformed area has been identified since the first observation. However, the magnitude of vertical deformation in this area has increased time by time. Meanwhile, the subsidence has increased from 5 - 16 centimeters in 17 months. The vertical deformation derived from InSAR was used to model the possible mechanism of land deformation in this region. The result shows that the fringes pattern is differ between the long-term and shorterm data analysis. The fringes pattern from long-term data analysis indicates a combination between faulting and dyke mechanism. Whereas, the fringes pattern derived from the shortterm data analysis indicates point source dislocation.Keywords : InSAR, Differential Interferometry, Mud Volcano, Land Deformation