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A 5.1-magnitude earthquake struck near Odisha’s Puri district on Tuesday, jolting residents awake at 6:10 am. The tremor centred 91 km deep in the Bay of Bengal, shook coastal areas from Balasore to Paradip, including Bhubaneswar and Cuttack. While no casualties or damage were reported, many described brief but unsettling shaking.
To ascertain whether Odisha lies at risk of further or even higher-intensity earthquakes, it is important to consider the factors contributing to it, namely the tectonic plates including the Mahanadi Graben.
Geological Faults and The Mahanadi Graben
The Mahanadi Graben is a geological structure formed due to tectonic activities, such as rifting and subsidence, which occurred during the breakup of the ancient supercontinent Gondwana.
It is part of the larger Mahanadi Basin, which extends both onshore and offshore along the eastern coast of India. The graben, characterized by faults and fractures, plays a crucial role in the region's tectonic activity.
Subsurface faults within the Mahanadi coastal basin, along with the geological faults in the Mahanadi river valley regions, including Bhubaneswar and Cuttack, contribute to the area's seismic activity. As such, the Mahanadi River valley falls within seismic zone III, indicating a moderate level of seismic activity.
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Moderate Risk, Major Concerns
Odisha falls under seismic zones II and III, indicating low-to-moderate risk. However, the Mahanadi Graben can generate quakes up to magnitude 6.0, as seen in a 2014 Bay of Bengal tremor.
While less active than the Himalayas, its location near populated cities like Bhubaneswar and Cuttack raises concerns. Further, thick sediments in the graben’s central zone amplify shaking, increasing damage risks.
Why Odisha Is Susceptible to Earthquakes?
Tectonic clashes between the Indian Plate and Myanmar Microplate beneath the Bay of Bengal drive the region’s seismicity. Subsurface faults in the Mahanadi Basin, including coastal and river valley fractures, add to the threat.
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Though large quakes are rare, experts urge preparedness. Monitoring fault activity, and public awareness campaigns are critical. Ongoing research, including geological surveys and historical data analysis, aims to refine risk assessments.
