Nepal quake triggered Sikkim disaster? Scientists to find out

New Delhi: Scientists are exploring whether the strong earthquake that struck Nepal and the surrounding region on Tuesday is responsible for the south Lhonak lake outburst, which triggered a flash flood in the Teesta river basin in Sikkim.

The lake outburst also resulted in the breach of the Chungthang dam, which is the largest hydropower project in the state. This dam is part of the 1,200-megawatt (MW) Teesta Stage III Hydro Electric Project, in which the state government is the majority stakeholder.

Satellite images released by the Hyderabad-based National Remote Sensing Centre showed that the area of south Lhonak lake reduced by over 100 hectares compared to its size on September 17. This suggests that the lake outburst caused a flash flood in the Teesta River basin in north Sikkim.

According to officials, at least eight people died and 70, including 23 army personnel, are missing.

“Earthquake that hit Nepal might be a cause of flash floods in Sikkim. The lake was already vulnerable and was spread across 168 hectares. Its area has now reduced 60 hectares, so about 100 hectares of volume of water has breached the level,” a senior official at the Central Water Commission (CWC) told PTI.

The official said though it’s difficult to ascertain right now but “a cloud burst does not cause such results”. Some experts who have been to the site think that the earthquake might have triggered the floods there.

He said the flood alerts were also shared with Bangladesh.

The NRSC satellite imagery showed that the lake was spread over approximately 162.7 hectares. Its area increased to 167.4 hectares on September 28 and drastically reduced to 60.3 hectares.

“In this satellite data, it is found that lake area is reduced drastically when compared with September 17 2023RISAT 1A MRS satellite data,” an NRSC report read.

Sikkim has 733 glacial lakes of which 288 are above the altitude of 5,000 metres, according to NRSC.

Four earthquakes, the strongest being of magnitude 6.2, jolted Nepal in quick succession on Tuesday with tremors reverberating through parts of India.