Liquefaction Hazard Mapping of Lucknow: A Part of Indo-Gangetic Basin (IGB)

Even though the size of the earthquake is moderate, presence of soft soil near the surface can cause devastating damage due to local site and induced effects like liquefaction. Evidence of liquefaction due to past Indian earthquakes was highlighted in many Paleo-seismic studies, particularly in the Himalayan region. The objective of this paper is subsurface characterization of part Indo-Gangetic Basin (IGB) and estimation of liquefaction hazards for the possible surface ground motions based on the region seismic study. Drilling of boreholes and measurement of standard penetration N values are carried out at selected locations for subsurface characterization. Possibility of liquefaction for soil deposits are assessed by comparing the grain size distribution curves obtained from laboratory tests with the range of grain size distribution curves of potentially liquefiable soils. The minimum factor of safety values has been identified for each location and presented in the form of maps showing FOS against liquefaction for average and maximum amplified peak ground acceleration (PGA) values. These maps have highlighted that the northern, western and central parts of Lucknow fall under very critical to critical for liquefaction while southern parts shows moderate to low critical area.