NEW DELHI: The National Centre of Seismology (NCS) under the Ministry of Earth Sciences recently installed six seismogram towers in Joshimath to monitor land subsidence and develop a robust solution. These towers will facilitate in compiling data for a study on whether the region has natural or man-made hydrological changes causing land subsidence.
The study will help prepare seismic micro-zonation maps, which are very useful in urban planning because they help predict the impact of earthquakes. After this, the Chamoli region, where Joshimath is located, will have its own building design code for future development. It will also help in long-term planning for the sustainable development of high seismic zones in the Himalayan region. The result of this study will come in December this year.
“We have put up six seismogram towers in the Joshimath,” said Dr OP Mishra, director of the National Centre for Seismology. There was already one seismogram tower set up in Joshimath in 1991. “The first tower measured earthquakes at a regional scale, whereas new towers are dedicated to measuring earthquakes at the local scale to get more detailed information. Based on it, Joshimath can be further divided into a number of seismic microzonation maps,” said Dr Mishra.
NCS had conducted a similar study in Gujarat’s Bhuj in 2003, after the great Bhuj earthquake of 2001. Dr Mishra and his team studied the crack density saturation there. M Ravichandran, Secretary, Ministry of Earth Sciences, said that this study would record time series data and try to confirm the theory of whether the region has hydrological change due to man-made activities or if climate change has caused land subsidence.
“There are lots of developmental activities going on in that area. At the same time, climatic effects such as frequent runoff rain cause cracks in subsurface levels. We will superimpose our findings to get reasons behind land subsidence,” he said. Scientists explain that the current genesis of land subsidence lies in the 6.8 magnitude earthquake in Chamoli in 1999.