Analysis of Liquefaction Potential based on CPT data in the Samas Coastal Area, Bantul Regency, Yogyakarta Special Province, Indonesia

Abstract

Bantul Regency is an area of the Special Region of Yogyakarta Province prone to earthquakes, mainly due to plate tectonic activity. On May 27, 2006, an earthquake of 6.3 Mw hit the Special Region of Yogyakarta and caused considerable damage in Bantul Regency. One of the impacts of the earthquake liquefaction, therefore, it is necessary to analyze the potential for liquefaction in the southern part of Bantul Regency. This research aims to determine the potential for liquefaction at the research location by considering the value of the liquefaction safety factor from the cone penetration test (CPT) data. The method used in this research is potential liquefaction analysis using the calculation method from the NCEER1998 consensus. The results of the potential liquefaction analysis are based on CPT data at three test points and correlated with core drilling data. The liquefaction potential zones in the CPT-1 are at a depth of 0.2 meters to 5.4 meters with a thickness of 5.2 meters. Whereas in CPT-2 potential for liquefaction zone that has the is at a depth of 0.2 -9.4 meters with a thickness of the liquefied layer of 8.4 meters, then in CPT-4, it is at a depth of 0.2 -11.2 meters with a layer thickness of 8.2 meters. Based on the three CPT data, the liquefied layers are in a layer of fine sand to coarse sand.