Identifikasi Potensi Tanah Longsor di Sekitar Desa Depok, Kecamatan Bendungan, Kabupaten Trenggalek Berdasarkan Data Mikrotremor

Fattah, Ridwan Maulana Al (2026) Identifikasi Potensi Tanah Longsor di Sekitar Desa Depok, Kecamatan Bendungan, Kabupaten Trenggalek Berdasarkan Data Mikrotremor. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5017221013-Undergraduate_Thesis.pdf - Accepted Version Restricted to Repository staff only until August 2026. Download (14MB) | Request a copy

Abstract

Desa Depok, Kecamatan Bendungan, Kabupaten Trenggalek merupakan wilayah dengan kerentanan tinggi terhadap tanah longsor akibat morfologi perbukitan vulkanik yang terjal, lapisan tanah pelapukan tebal dari Formasi Mandalika, serta curah hujan tinggi. Bencana longsor besar tercatat terjadi pada 19 Mei 2025 dan November 2025 yang menyebabkan korban jiwa dan kerusakan infrastruktur. Penelitian ini bertujuan untuk menganalisis karakteristik bawah permukaan dan tingkat kerentanan seismik wilayah Desa Depok menggunakan data mikrotremor tiga komponen yang diakuisisi pada 55 titik pengukuran. Pengolahan data dilakukan dengan metode HVSR (Horizontal to Vertical Spectral Ratio) menggunakan perangkat lunak Geopsy dan Dinver untuk memperoleh parameter frekuensi dominan (f₀), amplitudo H/V (A₀), indeks kerentanan tanah (Kg), nilai kecepatan gelombang geser rata-rata hingga kedalaman 30 meter (Vs30), ketebalan lapukan (h), serta pola particle motion. Hasil analisis menunjukkan nilai f₀ berkisar 0,65–5,54 Hz, A₀ antara 2,05–4,97, Kg antara 2,21–21,18, Vs30 antara 546,4–994,1 m/s, dan ketebalan lapukan 0–25,5 meter. Zona bagian utara hingga barat laut Desa Depok memiliki nilai Kg tinggi, sedimen lebih tebal, dan Vs30 lebih rendah yang mengindikasikan material lunak hasil pelapukan vulkanik intensif. Analisis pola particle motion menunjukkan perbedaan karakteristik gerakan partikel antar zona morfologi lereng. Area A (lereng atas/utara) didominasi kombinasi pola omnidirectional dan directional dengan orbit elips memanjang berorientasi N–S hingga NE–SW dan amplitudo besar, mencerminkan pengaruh kuat topografi serta rekahan dan bidang lemah bawah permukaan. Area B (lereng tengah) bersifat transisional dengan kombinasi pola omnidirectional dan directional berorientasi dominan E–W dan NE–SW yang mencerminkan heterogenitas struktur bawah permukaan pada zona lereng aktif. Area C (kaki lereng/selatan) umumnya berpola omnidirectional dengan beberapa directional lokal berorientasi beragam dan amplitudo lebih kecil, mengindikasikan kondisi bawah permukaan yang relatif lebih homogen dan stabil.
=================================================================================================================================
Depok Village, Bendungan District, Trenggalek Regency is an area with high vulnerability to landslides due to its steep volcanic hill morphology, thick weathered soil layers derived from the Mandalika Formation, and high rainfall intensity. Major landslide disasters were recorded on May 19, 2025 and November 2025, causing fatalities and infrastructure damage. This study aims to analyze the subsurface characteristics and seismic vulnerability level of Depok Village using three-component microtremor data acquired at 55 measurement points. Data processing was carried out using the HVSR (Horizontal to Vertical Spectral Ratio) method with Geopsy and Dinver software to obtain the dominant frequency (f₀), H/V amplitude (A₀), seismic vulnerability index (Kg), average shear wave velocity to a depth of 30 meters (Vs30), sediment thickness (h), and particle motion patterns. The analysis results show f₀ values ranging from 0.65–5.54 Hz, A₀ between 2.05–4.97, Kg between 2.21–21.18, Vs30 between 546.4–994.1 m/s, and sediment thickness of 0–25.5 meters. The northern to northwestern zone of Depok Village exhibits high Kg values, thicker sediments, and lower Vs30, indicating soft material resulting from intensive volcanic weathering. Particle motion pattern analysis reveals differences in particle movement characteristics across slope morphological zones. Area A (upper slope/north) is dominated by a combination of omnidirectional and directional patterns with elongated elliptical orbits oriented N–S to NE–SW and large amplitudes, reflecting the strong influence of topography as well as subsurface fractures and weak planes. Area B (middle slope) exhibits a transitional character with a combination of omnidirectional and directional patterns predominantly oriented E–W and NE–SW, reflecting subsurface structural heterogeneity within the active slope zone. Area C (lower slope/south) generally displays omnidirectional patterns with several locally directional patterns of varied orientation and smaller amplitudes, indicating relatively more homogeneous and stable subsurface conditions.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	mikrozonasi, HVSR, indeks kerentanan tanah, Vs30, particle motion, microzonation, HVSR, seismic vulnerability index, Vs30, particle motion
Subjects:	Q Science > QE Geology > QE539 Microseisms. Q Science > QE Geology > QE599 Landslides. Rockslides
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Ridwan Maulana Al Fattah
Date Deposited:	23 Jul 2026 06:59
Last Modified:	23 Jul 2026 06:59
URI:	http://repository.its.ac.id/id/eprint/136460

Actions (login required)

View Item