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"Next generation ground motion prediction models use shear-wave velocity over the top 30 m of subsoil (VS30) as an important assessment parameter of seismic ground surface motion. VS30 can be measured using invasive methods, such as boreholes, or non-invasive methods, such as multichannel analysis of surface waves (MASW). To evaluate this technique in a variety of near-surface conditions, MASW-derived shear-wave velocity profiles (s-wave velocity vs. depth) were statistically compared to direct borehole measurements from three locations of Merapi sediment found on the Universitas Muhammadiyah Yogyakarta (UMY) campus site. A detailed study of the effect from the total number of recording channels of MASW, sampling intervals, source offset, and receiver spacing was conducted near the borehole test site. The soil was classified as a medium soil or SD. The MASW method, which is non-destructive and non-invasive in nature and relatively faster in assessment, provides more reliable shear-wave velocity profiles, i.e. from 0 to 30 meters below the ground surface."

"Penelitian ini dilakukan untuk mengidentifikasi jenis tanah bawah permukaan pada lokasi penelitian serta memanfaatkan informasi tersebut untuk mengetahui zona layak bangunan pada lokasi penelitian. Penelitian ini menggunakan metode seismik refraksi dan MASW. Data yang digunakan adalah data Vp₃₀ dan Vs₃₀ untuk mendapatkan poisson ratio pada kedalaman rata-rata 30 meter. Data ini merupakan hasil dari pengukuran yang dilakukan di 14 titik di sekitar Universitas Indonesia. Hasil pengolahan data Vp₃₀ dan Vs₃₀ dihitung dengan menggunakan rasio Vp₃₀/Vs₃₀ dan menghasilkan nilai poisson ratio yang diinterpolasi untuk identifikasi jenis tanah. Dari hasil pengolahan dan analisis terdapat perbedaan nilai poisson ratio di wilayah utara dan selatan Universitas Indonesia, yaitu di wilayah utara memiliki nilai poisson ratio sebesar 0.38 – 0.41 dan di wilayah selatan memiliki nilai poisson ratio sebesar 0.41 – 0.45. Dari hasil tersebut dapat diprediksi bahwa di wilayah utara Universitas Indonesia memiliki jenis tanah yang lebih keras dibandingkan jenis tanah di wilayah selatan Universitas Indonesia.

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This research was conducted to identify the types of subsurface soil at the research site and utilize this information to determine suitable building zones at the research location. The study employed seismic refraction and MASW methods. The data used included Vp₃₀ and Vs₃₀ data to obtain the Poisson's ratio at an average depth of 30 meters. These data is the result of measurements taken at 14 points around Universitas Indonesia. The Vp₃₀ and Vs₃₀ data processing results are calculated using the Vp₃₀/Vs₃₀ ratio and produce Poisson's ratio values that are interpolated to identify soil types. The analysis revealed differences in Poisson's ratio values between the northern and southern regions of the University of Indonesia. In the northern region, the Poisson's ratio ranged from 0.38 to 0.41, while in the southern region, it ranged from 0.41 to 0.45. From these results, it can be predicted that the northern region of the University of Indonesia has harder soil types compared to the southern region."

"Perumahan Cluster Tranquility Depok sudah menunjukkan indikasi terjadinya penurunan tanah dari hasil keterangan warga. Aspal yang sobek serta tembok yang retak menjadi salah satu contohnya. Penelitian mengenai zona rawan subsidence di komplek perumahan Cluster Tranquility Depok menggunakan metode seismik refraksi dan Multichannel Analysis of Surface Waves (MASW) pada dua lintasan. Pada lintasan 1, analisis didukung oleh data geolistrik dari penelitian sebelumnya. Akuisisi data seismik refraksi dilakukan pada lintasan sepanjang 75 meter dengan 14 titik pukulan berinterval 6 meter, sedangkan akuisisi MASW menggunakan lintasan 33 meter dengan 12 pukulan palu untuk menghasilkan data profil 2D. Data dari kedua metode tersebut digunakan untuk menghitung nilai Poisson Ratio sebagai parameter analisis subsidence. Hasil seismik refraksi menunjukkan bahwa lapisan tanah pada lintasan 1 dan 2 di dominasi oleh unconsolidated layer atau tanah lapuk dengan kecepatan 200 – 350 m/s . Data MASW di kedua lintasan juga menunjukkan nilai kecepatan geser (Vs) <175 m/s yang mengindikasikan jenis tanah lapuk. Sedangkan nilai Poisson Ratio pada lapisan 1 dan 2 mengindikasikan lapisan tanah lempung jenuh (saturated clay) dan juga silt dengan rentang nilai 0.3-0.4. Diperkirakan jenis tanah di kedua lintasan merupakan tanah urukan. Data ini sejalan dengan hasil penelitian sebelumnya yang menyebutkan bahwa lapisan atas lintasan 1 berupa sedimen tidak terkonsolidasi namun adanya sesar tidak terkonfirmasi di penelitian ini.

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The Tranquility Cluster housing estate in Depok has shown indications of land subsidence from residents' testimonies. Torn asphalt and cracked walls are one example. Research on subsidence-prone zones in the Tranquility Cluster housing complex in Depok used refraction seismic and Multichannel Analysis of Surface Waves (MASW) methods on two tracks. On track 1, the analysis was supported by geoelectric data from previous research. Refraction seismic data acquisition was carried out on a 75-metre long track with 14 punch points at 6-metre intervals, while MASW acquisition used a 33-metre track with 12 hammer blows to generate 2D profile data. Data from both methods are used to calculate the Poisson Ratio value as a subsidence analysis parameter. Refraction seismic results show that the soil layer in trajectories 1 and 2 is dominated by unconsolidated layer or weathered soil with velocities of 200 - 350 m/s. MASW data in both tracks also show shear velocity (Vs) values <175 m/s which indicates the type of weathered soil. Meanwhile, the Poisson Ratio values in layers 1 and 2 indicate saturated clay and silt with a value range of 0.3-0.4. It is estimated that the soil type in both tracks is backfill soil. This data is in line with the results of previous research which states that the top layer of track 1 is unconsolidated sediment but the presence of faults was not confirmed in this study. "