Cost concerns delay safer building codes for Himalayas, Pg11

Key Highlights:

• The Bureau of Indian Standards (BIS) withdrew updated earthquake safety criteria for construction in the Himalayas and northeastern states.
• The withdrawal followed a Cabinet Secretariat order citing concerns about the impact on ongoing and future infrastructure projects.
• Government-commissioned studies suggest potential damage to structures in the Himalayan States is higher than current risk assessments.
• The withdrawn update was based on a probabilistic framework for assessing earthquake hazards, incorporating more variables than the existing approach.

Detailed Insights:

• The IS 1893 standard guides engineers and architects, delineating India into seismic zones from Zone II (calmest) to Zone V (highest risk, Himalayan front).
• The withdrawn update, originating from a 2024 paper, proposed earthquake hazard estimation methods aligned with global standards.
• The new map assigns peak ground acceleration (PGA) values of 0.15-0.75 g for Zones II through a newly introduced Zone VI, based on extensive earthquake data.
• Concerns exist that stricter codes and higher PGA values will significantly increase construction costs, impacting public spending on infrastructure projects.
• The existing framework doesn’t account for local soil conditions or data from 168 Himalayan monitoring stations, leading to underestimation of risk.
• The probabilistic assessment considers various factors influencing shaking, offering a more dynamic and comprehensive risk evaluation.

Key Concepts Involved:

• Peak Ground Acceleration (PGA): A measure of the maximum ground acceleration during an earthquake.
• Seismic Zones: Areas classified based on the probability and intensity of earthquakes.
• Probabilistic Framework: A risk assessment approach incorporating multiple variables to forecast potential hazards.