Liquefaction vulnerability analysis as a coastal spatial planning concept in Pariaman City – Indonesia

Abstract

Knowledge about the liquefaction vulnerability in Pariaman city which is prone to an earthquake is very much needed in disaster mitigation based spatial planning. This research was conducted by analyzing the potential of liquefaction vulnerability based on the Conus penetration to produce Microzonation of the susceptibility of subsidence due to liquefaction at 4 locations in Pariaman city, i.e Marunggi village, Taluak village, Pauh Timur village and Padang Birik-Birik village. Based on the results of the analysis using this method, the critical conditions of liquefaction found in the intermediate sandy soil to solid. The fine sand layer which has the potential for liquefaction is in sand units formed from coastal deposits, coastal ridges and riverbanks. This liquefaction vulnerability zones analysis is limited to a depth of 6.00 m due to the limitations of the equipment used. The results of the analysis show that the fine sand layer which has the potential for liquefaction occurs at a depth of> 1.00-6.00 m with the division of zones, i.e 1) High liquefaction in the sandy soil layer which has a critical acceleration (a) <0.10 g with shallow groundwater surface; 2) Intermediate liquefaction in the sandy soil layer which has a critical acceleration (a) between 0.10-0.20 g with shallow groundwater surface; and 3) Low and very low liquefaction in the sandy soil layer which has a critical acceleration (a) between 0.20-0.30 g with an average groundwater deep enough surface.