BIS Withdraws Draft Seismic Code 2025, Restores 2016 Standard

A major decision has recently been made regarding the Seismic Code (IS 1893), a code related to building and infrastructure safety in India.

The Bureau of Indian Standards (BIS) has withdrawn the proposed 2025 seismic code following concerns raised by the Ministry of Housing and Urban Affairs (MoHUA).

As a result, the 2016 seismic standard (IS 1893:2016) has been re-introduced.

The Ministry of Housing and Urban Affairs (MoHUA) had raised several significant concerns regarding the 2025 draft. Such as a significant increase in building construction costs, lack of adequate stakeholder consultation, practical difficulties in implementing the new regulations, and estimates that building construction costs in seismic zones V and VI could increase by approximately 10–15%, and large infrastructure projects could see costs increase by up to 50%.

Major Drawbacks of the Seismic Code 2025

According to experts, implementing the 2025 draft could pose several technical and economic challenges. Some examples include:

The design base shear for a 10-story RC frame in Delhi could increase by approximately 40%.

Hospitals in Guwahati could see this increase as high as 200%.

Industrial plants in Mumbai could require approximately 25% stronger structures.

School buildings in Itanagar require 70–120% more base shear.

Additionally, cities like Dehradun, Shimla, and Gangtok were projected to experience a 200–300% increase.

Proposed Changes to the Seismic Code 2025

The proposed 2025 revision was stated to be in line with international standards (US, Europe, and New Zealand). These new zones were primarily proposed for the Himalayas, the Northeast, and the Kutch region. Their key features include:

Advanced assessment of probabilistic seismic hazard

Shear-wave velocity-based system for soil classification

Use of vertical response spectra

Inclusion of a new high-risk Zone VI

According to the currently effective IS 1893:2016 standard, India is divided into four seismic zones:

Zone II – Low seismic risk

Zone III – Moderate risk

Zone IV – High risk

Zone V – Extreme risk. These zones are determined primarily based on past earthquake data and geological structure.

History of Seismic Zoning Maps in India

Seismic zoning maps have been created from time to time to understand earthquake risk in India.

1935 – First Seismic Map

Following the 1934 Nepal-India earthquake, the Geological Survey of India (GSI) prepared the first national seismic map in 1935.

In 1962, the Bureau of Indian Standards (BIS) released a new zoning map, dividing India into seven zones, ranging from 0 to VI.

The 1970 map divided India into five zones, ranging from I to V, and used the modified Mercalli intensity scale.

In 1984, a new update of India's seismic zoning map was released. Approximately 11% of the country's area falls in Zone V, 18% in Zone IV, 30% in Zone III, and the rest in Zone II.

What is the Bureau of Indian Standards (BIS)?

The Bureau of Indian Standards (BIS) is India's national standardization body, functioning under the Ministry of Consumer Affairs, Food and Public Distribution under the BIS Act 2016. It is headquartered in New Delhi.

It ensures product quality (ISI mark), gold/silver hallmarking (HUID), and standardization. Senior IAS officer Mr. Sanjay Garg is its Director General, effective November 2025.

BIS was established on April 1, 1987 (formerly the Indian Standards Institute - ISI). The BIS Act, 2016 (effective October 12, 2017)