Deformation Analysis of Jangli Road Section, Diponegoro University, Semarang Using Microtremor Method

The new road in Tembalang was built to reduce traffic congestion in the Gombel area. Jalan Jangli is an alternative road to Undip or vice versa. There is a deformed road on Jalan Jangli therefore by identifying the characteristics of the soil based on the analysis of the HVSR spectrum (Horizontal to Vertical Spectral Ratio) is used to assess the soil response to vibrations or earthquakes and identify the causes of deformation of Jalan Jangli. The study was conducted with microtremor with 48 measurement station, this study aims to determine the value of soil amplification (, seismic vulnerability index value (), and Ground Shear Strain (GSS) value on Jalan Jangli Baru Tembalang. Based on the results of the study, the distribution value of soil amplification ( on the road of Jangli Tembalang, the amplification value in the research area is 1.0008-6.61. The lowest value is at point 31 and the highest value is at point 36. The value of the seismic vulnerability index () on the road of Jangli Tembalang is in the range of 0.07-22.76. The highest Ground Shear Strain (GSS) value on the road of Jangli Tembalang is at point 18 with a value of . Analysis of deformation of the Jangli Road Section based on field conditions at point 36 has a high classification ( and (), the GSS value is 0.003 based on the table of relationships between strain and dynamic soil properties (Ishihara, 1996) including the phenomenon of cracking and land subsidence, this is in accordance with field conditions. Keywords: soil amplification, seismic susceptibility index and Ground Shear Strain.