Proceeding of the International ConferenceISBN 978-602-19142-0-5 on Mathematics and Sciences (ICOMSc) 2011 OP10 FUZZY CLUSTERING TO AUTOMATIC ZONATION OF URBAN AREA ON THE INCOMPLETE DATA OF HVSR PARAMETERS W. Utama 1 , Sungkono 2 , A.S. Bahri 3 , D.D. Warnana 4 Physics Department, Faculty of Mathematics and Natural Sciences, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia 1 widutama@yahoo.fr 2 hening_1@physics.its.ac.id 3 syaeful_b@physics.its.ac.id 4 dwa_desa@physics.its.ac.id Triwulan Civil Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia triwulan_marwan@yahoo.com Abstract. In this paper, it’s proposed an automatic procedure which performs the microzonation of seismic impacts in urban area based on an incomplete data of horizontal-to-vertical spectral ratios (HVSR) from ambient noise recordings collected at many measurement points. The derived data from HVSR ambient noise is usually accurate to frequency natural of sediment but that is seldom accurate to amplification of sediment, because of the geological amplification dependent of shaking source. In this technique, for classifying the area, the similarity among the spectral ratios incomplete data is optimized by using Gustafson−Kessel with partial distance strategy. The technique is applied to microzonation of seismic impact in the Surabaya city. The results show a good correlation to the geological condition and vulnerability index. Keywords: Microzonation, Urban area, HVSR parameters, Fuzzy clustering. 1 Introduction Seismic microzonation is the identification and mapping at local areas having different potential hazardous earthquake effect, i.e. ground shaking intensity, liquefaction, site effect, or land slide area [1]. It is commonly performed by geophysical and geological condition of different nature. For microzonation of ground shaking intensity and site effect can be used two parameters which are derived by horizontal-to-vertical spectral ratio (HVSR) of ambient noise recording at many sites. These are offer convenient, quick, practical and low cost tool to be used in the urban area, it’s applicable in the areas of low to moderate seismicity is limited by the time to gather a recordings number with good signal to noise ratio, hence it can be used very effectively formicrozonation[2]. The parameters result of HVSR analysis are frequency natural and amplification of site effect. The natural frequency and amplification correlated with damage building during earthquake, the high damage building is shown by low natural frequency or/and high amplification.