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Seismic Hazard Potential in Punjab Province of India Through Site Response Analysis and Its Liquefaction Assessment

Description: 

Punjab is a flat low land state occupied by thick deposits of various types of loose to dense soil due to active sedimentation and constitutes 1.53% of the geographical area of the country. The flat alluvial plains of Punjab have been formed by the deposition of Indo-Gangetic alluvium, with a maximum thickness of 300 meters over the base rocks of the Pleistocene and Holocene Siwalik Systems. Much of the Punjab shelf is bounded to the east by active fault systems viz MBT and MCT. All the geomorphological units in the region can easily amplify ground motion due to large impedance contrast and are liquefiable under strong seismic shaking. Effective shear wave velocity for soil/ alluvium column derived from both Geophysical and Geotechnical investigations at 350 locations in the region categorizes Punjab into D4, D3, D2 and D1 site classes according to the NEHRP and Global standard nomenclatures. 1D non-linear/equivalent linear site response analysis has been performed employing stochastically synthesized ground motion for a few near field earthquakes at engineering bedrock for all soil types. Site-specific generic Site spectra have been generated for all four site classes, together with Predominant Frequency (PF) and Site Amplification Factor (SAF) distribution in the region, with SAF varying between 2.21-3.77 times and PF varying between 1.0-5.8 Hz. Surface-consistent hazard is estimated by spectral convolution of firm rock Peak Ground Acceleration, which varies between 0.12g and 0.30g. Liquefaction susceptibility analysis performed for both the 1905 Kangra earthquake of Mw 7.8 and the probabilistic scenario exhibit Liquefaction Potential Index (LPI) variation from Low to Severe. These results are expected to aid in adopting safe building code provisions and also help in working out regulatory measures for safeguarding against earthquake-induced devastations and promulgating management practices toward effective relief, rescue and rehabilitation.

Session: Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict? [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Anand Srivastava

Student Presenter: Yes

Invited Presentation: 

Authors