Aulya, Ratu Shelma (2026) Analisis Deformasi Menggunakan SBAS Time Series InSAR dan Korelasinya dengan Aktivitas Seismik. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Gunung Semeru merupakan gunung api aktif dengan karakter sistem kawah terbuka yang memerlukan pemantauan deformasi untuk memahami dinamika aktivitas vulkaniknya. Penelitian ini bertujuan untuk menganalisis deformasi permukaan Gunung Semeru periode Mei 2025 hingga Februari 2026, memvalidasi hasil InSAR terhadap data GNSS, serta mengkaji hubungannya dengan aktivitas kegempaan. Metode yang digunakan adalah time series SBAS-InSAR menggunakan LiCSBAS terhadap citra Sentinel-1 orbit ascending dan descending. Hasil LOS dari kedua orbit didekomposisi menjadi komponen vertikal dan timur–barat, kemudian dibandingkan dengan data GNSS. Hasil penelitian menunjukkan bahwa fase pra-erupsi didominasi uplift gradual dengan perubahan vertikal rata-rata +6,8 mm. Pada fase ko-erupsi, deformasi relatif kecil dan terkonsentrasi pada zona proximal 0–3 km dari kawah, sedangkan fase pasca-erupsi masih menunjukkan uplift sebesar +0,6 mm. Validasi terhadap GNSS dilakukan setelah offset datum konstan kedua deret dihapus dan menunjukkan kesesuaian yang bervariasi, dengan RMSE LOS umumnya 7–14 mm; dua kombinasi mencapai NSE positif sementara sisanya tetap negatif. Kesesuaian terbaik pada arah LOS diperoleh di stasiun LEKR orbit descending dengan r = 0,338, RMSE = 12,5 mm, dan NSE = +0,11. Hasil dekomposisi menunjukkan bahwa komponen vertikal lebih layak dijadikan dasar interpretasi dibandingkan komponen timur–barat, dengan NSE vertikal positif pada stasiun TWSG (+0,15) dan ARGO (+0,11) serta korelasi tertinggi pada stasiun TWSG (r = 0,385), meskipun kesesuaian kuantitatif komponen timur–barat terhadap GNSS masih terbatas. Integrasi SBAS-InSAR, GNSS, dan data kegempaan menunjukkan adanya pola uplift sebelum erupsi, perubahan kecil saat erupsi, dan uplift lanjutan setelah erupsi 19 November 2025.
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Mount Semeru is an active volcano with an open-vent system, requiring surface deformation monitoring to better understand its volcanic dynamics. This study aims to analyze the surface deformation of Mount Semeru from May 2025 to February 2026, validate InSAR-derived deformation with GNSS data, and examine its relationship with volcanic seismic activity. The method used in this study is SBAS-InSAR time-series analysis using LiCSBAS applied to Sentinel-1 ascending and descending orbit images. The LOS deformation from both orbits was decomposed into vertical and east–west components and then compared with GNSS observations. The results show that the pre-eruption phase was dominated by gradual uplift, with an average vertical displacement of +6.8 mm. During the co-eruption phase, deformation was relatively small and concentrated within the proximal zone of 0–3 km from the crater, while the post-eruption phase still showed continuing uplift of +0.6 mm. Validation against GNSS was carried out after removing the constant datum offset between the two series and showed varying levels of agreement, with LOS RMSE generally ranging from 7 to 14 mm; two combinations reached positive NSE values while the others remained negative. The best LOS agreement was obtained at the LEKR station on the descending orbit, with r = 0.338, RMSE = 12.5 mm, and NSE = +0.11. The decomposition results indicate that the vertical component remains more suitable as the basis for interpretation than the east–west component, with positive vertical NSE values at the TWSG (+0.15) and ARGO (+0.11) stations and the highest correlation at the TWSG station (r = 0.385), although the quantitative agreement of the east–west component with GNSS remains limited. The integration of SBAS-InSAR, GNSS, and seismic data indicates a pattern of uplift before the eruption, minor deformation during the eruption, and continued uplift after the 19 November 2025 eruption.
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