Application of Generalized Reciprocal Method on 2D Seismic Refraction Data in Mt. Manglayang, West Java
Abstract
The imaging of shallow subsurface structures, weathered rock thickness and velocity propagation distribution of the rocks can be identified by seismic refraction. This method is one of the geophysical exploration methods utilizing refracted wave once it reaches the boundary of subsurface layer. In this research we used the generalized reciprocal method (GRM) as one of the robust processing methods in analyzing subsurface data. This method was chosen due to its accuracy in interpreting shallow subsurface layer with highly undulating refractors by determining time velocity analysis, XY optimum distances, and time depth analysis, then, the expected depth values can be achieved. The acquisition of data for this research was conducted using 13 geophones with forward and reverse sources, the data were then picked to get travel time values and inverted to obtain real geological setting of the earth. The results were interpreted as 2 layers, the first layer had a velocity distribution of 499.289 m/s which was identified as a weathered layer with a thickness of about 4.74 meters, whereas the second layer was interpreted as clay rock with velocity distribution of 1270.433 m/s with the thickness reached up to 16 meters.
Keywords: generalized reciprocal method, 2D seismic refraction
References
[1] Suwarsono R, NK. “Visualisasi struktur bawah permukaan tanah menggunakan metode Hagiwara. Jurnal Gradien; 2009. pp. 30–3.
[2] Kanao M, Yamashita A. “Characteristic seismic waves associated with cryosphere dynamics in eastern dronning maud land, East Antarctica.,” International Journal of Geophysics. p. 2012.
[3] Nurdiyanto BD. “Penentuan tingkat kekerasan batuan menggunakan seismik refraksi.,” Jurnal Meteorologi dan Geofisika. vol. 12, no. 3, p. 212, 2011. https://doi.org/10.31172/jmg.v12i3.103.
[4] Leung TM. Controls of traveltime data and problems of the generalized reciprocal method. Geophysics. 2003;66(6):1626–32.
[5] Orlowsky D, Ruter H, Dressen L. “Combination of common midpoint refraction with generalized reciprocal method.,” Elsevier. J Appl Geophys. 1998;39:221–35.
[6] Palmer D. The resolution of narrow low-velocity zones with the generalized reciprocal method. Geophys Prospect. 1991;39(8):1031–60.
[7] Salim A. Analisis data seismik refraksi dengan metode generalized reciprocal. ComTech. 2012;3(1):162–5.
[8] Hamdy H. “Is the optimum XY spacing of the Generalized Reciprocal Method (GRM) constant or variabel?” In: 67th Annual Meeting of The German Geophysical Society. El Mansoura: Aachen (2007).
[9] Derecke P. “An introduction to the Generalized Reciprocal Method (GRM) of seismic refraction,” (1981).
[10] Budi S. Pemetaan tingkat kekerasaan batuan menggunakan metode seismik refraksi. Depok: Universitas Indonesia; 2008.
[11] Satrio W. Geologi dan petrologi kawasan Manglayang. Institut Teknologi Bandung. Bandung: Bandung Timur, Jawa Barat; 2016.
[12] Wiqoyah Q. Pengaruh kadar kapur, waktu perawatan dan perendaman terhadap kuat dukung tanah lempung., 2006.