Microzonation of potential liquefaction in Sidoarjo mud volcanoes (LUSI).

LUSI still holds potential hazards, for the past 16 years in addition to the mudflow process that is still active, the presence of high pore water pressure in the affected area has caused various subsequent disaster impacts. When the pore pressure is increased, the effective stress decreases and has an impact on reducing the strength of the soil / rock. Liquefaction has a high potential to occur in LUSI, the main conditions for triggering liquefaction have been met in the study area including the presence of shallow groundwater levels, soil properties, and seismicity factors. The research method is an empirical analysis based on standard penetration test (SPT) based evaluation, SPT tests from 26 drill points with N-SPT values <15. Using the seismic code with a 10% in 50 years and site characteristics, Sidoarjo City has an earthquake PGA of 0.28 to 0.38g. The results of the analysis obtained the value of FS<1, Liquefaction Potential Index (LPI) from low to very high. Analysis with 2 methods in general the results of FS and LPI showed a very high potential for liquefaction in the northern and eastern areas of the study site, while the low potential was in the southern and western areas. The potential for liquefaction is largely determined by soil properties, the distribution of loose sand layers, and the depth of the groundwater level in the study area. The results from the microzonation mapping of the potential for liquefaction will provide an important tool in efforts to mitigate and control Sidoarjo mud volcanoes in the future. [ABSTRACT FROM AUTHOR]