Scientists decode the reason behind Chamoli disaster

• Avalanche in Chamoli district in the Uttarakhand state led to a significant casualty of more than 200 people and a substantial economic loss.
• Now scientists have been able to decode the reason behind the disaster.

Chamoli Disaster

• The flash flood occurred on February 7, 2021, at the Nanda Devi National Park in Uttarakhand's outer Garhwal Himalayas.
• A landslide, an avalanche, or a glacial lake outburst flood are assumed to have caused it.
• Flooding has occurred in the Chamoli district, most notably in the Rishiganga River, the Dhauliganga River, and, ultimately, the Alaknanda, the Ganges' principal headstream.

Findings by the Scientists

• The scientists have found that the region was seismically active before the disaster hit.
• They also found a noteworthy sequence of precursory signals of rock-ice detachment preceded by a formation of a new structure via self-assembly or self-organization called the dynamic nucleation phase.
• Retreating Himalayan glaciers and associated melt along with unstable slopes are subject to trigger landslides by rainfall during monsoon or by induced seismicity in the region.
• The snow, ice and rock avalanches may threaten people and infrastructure downstream in mountainous areas worldwide.
• This is why the area requires constant monitoring of seismicity as well as glacier status.

Wadia Institute of Himalayan Geology (WIHG)

It has been actively involved in understanding the processes responsible behind such disasters and focusing on detecting significant and unfelt activities with a dense network of seismic stations in the vicinity of Himalayan glaciers.

• They have also tried to trace the reasons behind the disaster that took place in Chamoli.

Recent Observations

• The group of 9 scientists analyzed the satellite images of the avalanche zone and found that it shows gradual growth of cracks and the joint near the crown of the weak wedge that has controlled the head scarp for the last 5 years.
• These cracks further started to open up and led to successive advancement of a weak zone near the crown of the wedge failure.
• The initiation of ice-rock mass avalanche has been recorded as seismic precursors, which were continuously active for 2.30 Hr, before the main detachment took place.
• Scientists analyzed and verified the seismic signals with field evidence to evaluate the velocity of dynamic flows and associated impacts.
• Such high-quality seismic data allowed reconstructing the complete chronological sequence and evaluating effects since the initiation to the advancement of debris flow.

Way Forward

• Seismic monitoring systems are well suited to detect mass movements such as debris flow, landslides, avalanches, etc.
• The ability to see such activities by a seismic network before the main failure could provide a scope for developing an early warning system for the region.
• An integrated early warning system can alert the people towards the mitigation of any such impending disaster.
• The Early Warning System (EWS) should be based on seismic data from the seismometers, hydrological data from automatic water level recorders and meteorological data from automatic weather stations installed.

Exam Track

Prelims Takeaway

• Nucleation process
• Glacial Outburst
• Early Warning System (EWS)

Mains Takeaway

Q. Discuss various anthropogenic factors responsible for the Chamoli disaster. Analyze the steps taken by the government to deal with disasters like this.