Twenty-five years after the devastating earthquake that brought the Kutch region into sharp focus, seismic researchers gathered in Gandhinagar to assess the evolving understanding of Gujarat's earthquake dynamics. The 2001 Bhuj earthquake, measuring 7.7 on the Richter scale, stands as one of the most significant seismic events in peninsular India's history, second only to the 1819 Allah Bund earthquake believed to have reached magnitude 7.7 to 8.2.
Conference Reveals Ongoing Tectonic Movements
The Institute of Seismological Research (ISR) recently hosted a three-day conference titled 'Intraplate and Himalayan Seismology: Developments in the Last 25 Years', bringing together experts to examine various aspects of Gujarat's seismology and future hazards. Dr Sumer Chopra, former director of ISR and current professor at IIT Roorkee, presented crucial findings about the region's geological movements.
Divergent Plate Movements in Gujarat
Dr Chopra highlighted that while the Kutch and Saurashtra regions continue moving northwards in alignment with the Indian plate's overall direction, northern parts of mainland Gujarat show contrasting movement. The area identified in seismological terms as the Cambay Rift is actually moving southwestwards, creating conditions for strain accumulation that could potentially lead to future seismic events.
Understanding the 2001 Bhuj Earthquake Mechanism
The catastrophic 2001 event resulted from intraplate activity influenced by multiple factors, with researchers now recognizing the significant role of mantle fluids in seismic activities. ISR research has revealed the presence of a fluid reservoir located 40-45 kilometers deep in the uppermost mantle of eastern Kutch.
Fault Systems and Fluid Dynamics
The South Wagad Fault (SWF), a near-vertical dipping fault that traverses the entire crust, acts as a primary channel for fluid flow to upper crustal depths. Along with its splay fault, the North Wagad Fault (NWF), this system directly caused the 2001 Bhuj earthquake and continues to influence ongoing seismic activity in the region.
Dr Chopra explained to TOI that the 2001 event generated numerous aftershocks, with the region remaining seismically active to this day. "The earthquake activated some faults through stress transfer that might not have been active for extended periods," he noted. "While Gujarat continues to experience low-magnitude earthquakes regularly, we interpret this as periodic energy release rather than accumulation for a single major event."
Regional Seismic Stability Assessment
Compared to the persistently active Kutch region, other areas of Gujarat demonstrate relative stability and present lower risks for large-scale tremors. However, Dr Chopra identified specific locations including Gir, Bharuch, and Banaskantha that have shown seismic activity in recent years, warranting continued monitoring.
Post-2001 Seismic Patterns
Dr O P Mishra, director of the National Centre of Seismology, presented research indicating that the Kutch region has experienced a prolonged series of earthquakes continuing since 2001. These events have varied in magnitude from 2-3 to 5-6 on the Richter scale, with the total seismic energy released collectively measuring approximately 2.15×10^16 joules.
Dr Mishra provided a striking comparison, noting that this energy release equates to multiple atomic bomb explosions. He specifically analyzed a 5.3 magnitude earthquake that occurred in Kutch during June 2020, which created a rupture area spanning about 20 square kilometers.
"The new seismic events continue occurring near the 2001 mainshock epicenter, providing valuable insights into emerging rupture patterns," Dr Mishra explained during his presentation.
International Collaboration and Knowledge Sharing
The conference, organized in collaboration with the Seismological Society of America, facilitated knowledge exchange between researchers from various countries working in intraplate regions. International experts shared their experiences and research findings with ISR scientists, contributing to a more comprehensive understanding of seismic hazards in Gujarat and similar geological settings worldwide.
This gathering of seismic experts marks a significant milestone in earthquake research, combining twenty-five years of data collection, analysis, and technological advancements to better prepare Gujarat for future seismic challenges while deepening scientific understanding of intraplate earthquake mechanisms.
