The Council Of Scientific And Industrial Research -National Geophysical Research Institute (CSIR-NGRI) has launched an ‘Environmental Seismology’ group to develop a ‘Landslide and Flood Early Warning System’ for the Himalayan region based on real-time monitoring with dense seismological networks, coupled with satellite data, numerical modelling and geomorphic analysis.
“This would give a crucial warning several hours prior, which will save human lives and property,” said Director V.M. Tiwari on Friday. The need for such an early warning system was necessitated following February’s rockslide flood disaster in Chamoli (Uttarakhand), where a steep glacier on the Nandadevi peak in Garhwal Himalaya got detached, causing a major avalanche and inducing flash floods in the Rishi Ganga and Alaknanda rivers. It killed several persons downstream and caused severe damage to two power plants. “We run a dense network of about 100 seismograph stations in Uttarakhand in western Himalayas and these events were well recorded,” he said.
Scientists at the NGRI in collaboration with German scientists at GFZ, Potsdam, used spectrogram analysis techniques to identify and separate out various phases, including that of the rockslides, debris flow and flooding of the event. The broadband seismic network enabled a complete spatio-temporal tracking of the entire disaster sequence using polarisation and back-tracing approaches, said Dr. Tiwari.
A major player
Since climate change was a major player in accelerating ice loss through glacier melt and flash floods caused by glacier retreat, major efforts were needed to maintain the fragile ecosystem in the multi-hazard prone Himalayan region. This also had important implications for the planning of infrastructural development of dams, power plants and other projects by governments, which were of great strategic and societal importance to the country, said the Director.
The joint study had been published in the latest issue of the prestigious American Science journal, for which Dr. Tiwari and other colleagues D. Srinagesh, N. Poornachandra Rao and research associates Rajesh R, Himanshu Paul, Prantik Mandal and G. Suresh contributed from the NGRI.
Teleseismic signals from the beginning of this event were recorded at different stations on a regional seismic network up to 100 km from the disaster and demonstrated the potential for these far-away monitoring stations to be useful for early warning, the paper said.
While a seismic network designed for earthquake detection may not be ideal for the monitoring of geomorphic events, an evaluation of the expected anthropogenic (man-made) and environmental noise levels should be carried out before locating stations for geomorphic event detection.