Key Takeaways

• At least 14 workers died after a methane gas explosion collapsed part of an under-construction tunnel.
• 11 workers remain trapped as National Disaster Response Force teams intensify search-and-rescue operations.
• The accident occurred within a NHPC hydropower project tunnel designed to channel water from the Teesta River.
• Authorities suspect methane gas trapped in rocks ignited, causing dense fumes and toxic conditions.

On Monday, a catastrophic Sikkim tunnel collapse claimed the lives of at least 14 workers after a sudden methane gas explosion triggered a major incident in India’s north-eastern state.

Officials confirmed that the disaster unfolded approximately 1.5 kilometers (0.9 miles) deep inside the tunnel, which is currently being developed by the state-owned National Hydroelectric Power Corporation (NHPC). The structure is a critical component of a larger NHPC hydropower project intended to channel water from the nearby Teesta River directly to the facility's turbines.

According to a statement released by NHPC, the incident began with a sudden burst of suspected methane gas that was trapped or embedded within the surrounding rocks. This release led to an explosion that generated dense fumes and toxic gases, creating hazardous conditions for everyone inside. A separate statement from the Sikkim government corroborated the cause, attributing the accident to "methane gas combustion."

Methane is a naturally occurring gas that frequently remains trapped underground in geological formations. When tunnelling activities release this gas into a confined space, it poses a severe risk. If the gas comes into contact with any spark or ignition source, it can instantly ignite or explode. A government official explained this mechanism to clarify the sudden nature of the disaster.

There were 27 individuals working in various sections inside the tunnel at the time of the explosion. Miraculously, two workers managed to escape the immediate blast zone. However, the remaining 25 were left trapped in the hazardous environment.

Superintendent of Police Sonam D Bhutia provided a grim update on the situation to the BBC on Wednesday morning. "Of the 25 people who were trapped, we have recovered 14 bodies so far, and teams are working to locate the 11 other men," he stated. The ongoing search-and-rescue operation is currently focused on a specific 200-metre zone where rescue teams believe the remaining survivors might still be located, according to NDRF officer Mohsen Shahedi, who spoke to ANI news agency.

The identities of the victims have been partially established by police authorities. Seven victims have been identified so far, revealing a diverse mix of workers involved in the project. One victim is from Sikkim, while the others are migrants hailing from the states of West Bengal, Uttarakhand, and Assam. Officials noted that the exact cause of death for each individual will be ascertained only after post-mortem examinations are completed.

As rescue operations continue, the NHPC has taken immediate steps to understand the root causes of the tragedy. "We have engaged a team of experts to find out what exactly happened and how. We will take action on the basis of the findings," Tamang told reporters, promising accountability and further investigation.

Sikkim Tunnel Collapse Impacts Future Hydropower Safety

The methane gas explosion that devastated the Sikkim tunnel has underscored the inherent dangers of high-altitude infrastructure projects. With 12 confirmed deaths and 11 workers still unaccounted for, the incident highlights the critical risks associated with tunnelling in the geologically complex Himalayan region. The immediate future for the NHPC hydropower project will likely involve a thorough suspension of work to allow for comprehensive safety audits and gas mitigation strategies. As authorities investigate the specific conditions that led to the gas pocket's ignition, the broader hydropower sector may face increased regulatory scrutiny regarding methane management in deep tunnelling operations, potentially leading to stricter safety protocols for future large-scale energy infrastructure developments in seismic and geological sensitive zones.