Evaluation of Soil Liquefaction Using SPT Data at Boyolali Regency, Central Java

On 27 May 2006 at 05:54 local time, a major earthquake with a moment magnitude (Mw) of 6.3 occurred in Yogyakarta Province. This earthquake was widespread causing several damages in Yogyakarta Province and Central Java Province. One of the regencies in Central Java Province impacted was Boyolali Regency. This research aims to evaluate soil liquefaction based on the Standard Penetration Tests (SPT) in Boyolali Regency. Evaluation of soil liquefaction was necessary to minimize the damage as a preliminary in determining mitigation methods that can be applied. Besides Mw 6.3 earthquakes, according to SPT Data, several factors that triggered liquefaction were found in this study area such as a shallow groundwater table and the existence of a poorly graded sandy soil layer. The liquefaction was evaluated by comparing the Liquefaction Severity Index (LSI) and the Liquefaction Risk Index (LRI) using the simplified method. Based on the analysis, the result showed that Boyolali Regency had a value of LSI in the range of very low until low severity and a value of LRI in the range of low until the high risk.