National Centre for Seismology Highlights Higher Earthquake Risks in Eastern Bhubaneswar

Eastern Bhubaneswar faces heightened seismic vulnerability due to soft soil conditions and deep underlying bedrock, according to National Centre for Seismology director Dr. G. Suresh. Speaking at a workshop in the city, he highlighted that high-rise structures in these areas are particularly susceptible to amplified ground shaking during tremors.

Detailed Microzonation Study Findings

The assessment covered a 420-square-kilometer area of the capital's development plan, involving measurements at 1,650 locations, deep borehole investigations, and laboratory analysis of more than 1,200 soil samples. While most of Bhubaneswar features stiff ground conditions favorable for foundations, the eastern growth belt along river corridors contains thick alluvial deposits with engineering bedrock located as deep as 86 meters.

Ground Motion Amplification Risks

Researchers observed that certain eastern locations could experience peak ground acceleration of 0.14 to 0.17 g, significantly higher than the 0.08 g design shaking prescribed under national codes. For stronger earthquake scenarios, the study projected peak acceleration of 0.20 to 0.27 g in vulnerable pockets such as Chakeisiani, Pahala, Old Town, and Uttara.

Resonance and Structural Vulnerability

Dr. Suresh explained that low ground frequencies below 4 hertz in the eastern belt can match the natural vibration frequencies of tall structures, creating resonance that multiplies shaking intensity. Although Odisha is frequently threatened by Bay of Bengal cyclones, active seismic fault lines in Zone III moderate-risk regions also expose densely built urban areas to potential earthquake damage.