Landslide Analysis Using Seismic Refraction Tomography And MASW: a Case Study in Ponorogo, East Java, Indonesia

Yusri Prayitna, Widya Utama, Dwa Desa Warnana

Abstract


Bentuk morfologi kabupaten Ponorogo yang terdiri dari dataran tinggi dan perbukitan membuat daerah ini rentan terhadap bencana longsor. Berdasarkan data BNPB (Badan Nasional Penanggulangan Bencana) tahun 2013 hingga 2017, telah terjadi  peristiwa tanah longsor sebanyak 77 kali dan 35% diantaranya terjadi di kecamatan Ngrayun dan Slahung. Salah satu daerah yang berpotensi mengalami longsor adalah Desa Tugurejo di Kecamatan Slahung. Penelitian ini bertujuan untuk mengetahui sifat fisis batuan bawah permukaan dengan menggunakan metode SRT (Seismik Refraction Tomography) dan MASW (Multi-channel Analysis of Surface Waves). Distribusi kecepatan gelombang seismik yang ditentukan dari SRT dan MASW di lokasi penelitian menunjukkan zona dengan porositas yang lebih tinggi yang diinterpretasikan untuk mewakili tingkat dan kedalaman pergerakan massa batuan. Kecepatan gelombang-P dan gelombang-S menunjukkan kecepatan yang sangat rendah yaitu 500-1200 m/s dan 100-250 m/s pada kedalaman hingga 5 m.

Abstract¾ Ponorogo district morphology form consisting of highlands and hills make this area vulnerable to landslides. Based on the BNPB (National Disaster Management Agency) data from 2013 to 2017, 77 landslides and 35% have occurred in Ngrayun and Slahung sub-districts. One area that has the potential to experience landslides is Tugurejo village in Slahung District. This study aims to determine the physical properties of subsurface rocks using SRT (Seismic Refraction Tomography) and MASW (Multi-channel Analysis of Surface Waves). The seismic velocity distribution defined from the SRT and MASW at the study sites shows a zone with a higher porosity that is interpreted to represent the level and depth of rock mass movement. P-wave velocity and S-wave indicates very low velocity of 500 – 1200 m/s and 100 – 250 m/s at depths up to 5 m.


Keywords


seismic Refraction Tomography, Multi-channel Analysis of Surface Waves, Landslide.

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References


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DOI: http://dx.doi.org/10.12962/j23378557.v5i2.a5025

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