ORIGINAL PAPER Identification of Possible Liquefaction Zones Across Guwahati and Targets for Future Ground Improvement Ascertaining no Further Liquefaction of Such Zones Safik Khan . Abhishek Kumar Received: 29 September 2018 / Accepted: 27 November 2019 Ó Springer Nature Switzerland AG 2019 Abstract Liquefaction is associated with the loss of shear strength of soil, causing considerable damages. The Northeast Indian region has experienced many major (M C 7.0) to great earthquakes (EQs) such as 1869 Cachar EQ and 1897 Shillong EQ. As a consequence, Guwahati city had faced large scale damage and significant induced effects such as liquefaction during past EQs. At present, Guwahati is the largest business hub of the northeast India. Further, Guwahati is also amongst the list of cities, Government of India has shortlisted to be developed as ‘‘smart city’’. For these reasons, the city attracts lots of infrastructural growth in the times to come. In the present work, the liquefaction potential of Guwahati subsoil is evaluated. For the purpose, seismic scenar- ios experiences during 1869 Cachar EQ (M w = 7.5), 1897 Shillong EQ (M w = 8.1), average horizontal seismic coefficient given by IS 1893 (Part 1): 2016 (seismic zone V) and maximum amplified peak ground acceleration (PGA) values obtained based on site-specific subsoil data are considered separately. In- situ subsoil properties are obtained from 244 boreholes (BHs) till 30 m depth and maps showing possible liquefiable zones across Guwahati are developed. In addition, maps showing target SPT-N value (N improved ), to be obtained at above liquefiable zones after ground improvement, ensuring no further lique- faction, are also developed. Thus, the present study collectively identify zones which may undergo lique- faction during future EQs and further, how much improvement in the subsoil strength properties are required so that the above found liquefaction can be avoided, is also estimated. Obtained results and proposed values will provide very useful information to field engineers regarding where and how much ground improvement is required for avoiding future liquefaction. In addition, the present study is very helpful for city planning and microzonation studies. Keywords Subsoil  Liquefaction  Guwahati  Ground improvement  Scenario earthquakes 1 Introduction Liquefaction is a phenomenon where shear strength of soil is lost when subjected to dynamic loading, specifically during EQ loading. It occurs due to increase in pore water pressures and development of large shear strains during cyclic loading in the soil. Soil liquefaction is a major threat to various buildings and infrastructures and may induce ground failures. After significant damages caused by devastating EQs during 1964 Good Friday EQ in Alaska and 1964 S. Khan  A. Kumar (&) Department of Civil Engineering, Indian Institute of Technology, Guwahati, India e-mail: abhiak@iitg.ernet.in; abhitoaashu@gmail.com 123 Geotech Geol Eng https://doi.org/10.1007/s10706-019-01128-0