Y.S. RANA , CHANDIGARH– Earthquakes represent the Next tectonic event is expected in the Shivaliks along the path of the old Saraswati River and the present Ghaggar river, says Dr Ritesh Arya, Guinness world Record Holders and an international famed Geologist of Kasauli. He said that the foothill areas like Parwanoo, Pinjore and Panchkula fell into this zone. He feels that earthquake in Nepal is a warning to the authorities and private institutions bent on constructing cities with high-rise buildings and big industrial areas in North India especially if we are talking about Shimla, Solan, Parwanoo and Surajpur axis located near Chandigarh.
Substantiate the findings, Dr Arya said that today these towns were located in zones which were geologically upside down by this he meant that older rocks were resting on the younger rocks as a result of which the entire sequence was geologically very fragile and susceptible to greater damage in the event of epicenter being concentrated upon these zones.
Surajpur region is located on the Surajpur Thrust where Tehtyan Himalayan Limestone sequence is resting over the younger Shiwalik formation. In Parwanoo the Lower Shiwalik Formation (15 million years old) comprising of sandstone and shale representing fresh water terrestrial environment is overlain by Subathu Limestone and black carboniferous (age approx 55 million years old) representing marine environment at the time deposition. “This gap in the depositional history is the matter of concern and is also the cause of concentration of seismic activity in the region,” warns Dr Arya.
He has done geological fieldwork around Surajpur-Shimla Highway and found that this section was very well exposed in the Parwanoo sector 4 Area where an experimental well was drilled few years back to monitor the earthquake but there was a few practical problems and the instrument started recording the movement of the trucks and heavy vehicles and the project was prematurely abandoned.
Dwelling on his study, he said that in Barog or Solan, the Subathu formation which was 55 Million years old was being overlain or thrusted by Krol Formation which was more than 400 Million years old. Similarly in Shimla town, the metamorphosed Shimla Slates are overlying the younger sedimentary tertiary sequence of Subathu, says he.
Today these have become crowded epicenters with tourism, educational institutes and industries coupled with high-rise buildings. All this has resulted upcoming of haphazard construction on either side of Kalka-Shimla National Highway in the absence of proper geotechnical institutions to control and design the buildings and certify or lay standards necessary for these to withstand the seismic activity. “The whole concept of sustainable development goes for a six in the area,” said Dr Arya.
Commenting on the reason he said that there was a tectonic shift of the Indian plate at a rate of 47 millimeters a year towards Chinese plate. Geologically, the region is highly folded and faulted due to northward tectonic movement of Indian Plate which dragged for millions of years to finally collide with Chinese plate.
He regretted that there was no institute dedicated to study and monitor or predict earthquakes in spite of the fact that earthquakes have the greatest impact and cause instant devastation on the crowded habitations and stressed on the need of setting up of geotechnical institute and monitor data collected from the bore wells to seriously study and reinterpret data for predicting earthquakes and to understand the global warming phenomenon. Need of the hour is to take all the necessary precaution to nullify the impact of any seismic activity up to Richter scale 9. He revealed that during the earthquake at Latur it was found a surge in the level of ground water several hours before the event occurred. It had been observed that the water level either increased or decreased sharply before a tremor hits an area. Besides, its chemical composition was also altered due to an increase in Radon gases because of excessive of radioactivity before and after the event.
Of the earthquake-prone areas, 12 per cent is prone to very severe earthquakes, 18 percent to severe earthquakes and 25 per cent to damageable earthquakes.
From 1819 to1950, the country had experienced five earthquakes of 8 or more magnitude at Richter Scales. On June 16, 1819, an earthquake of 8 magnitude at Richter Scales was occurred in Kutch (Gujarat); June 12, 1897 of 8.7 magnitude in Shillong; in 1905 of 8 magnitude in Kangra (Himachal Pradesh); January 15, 1934 of 8.3 magnitude on Bihar-Nepal Border; August, 1950 of 8.5 magnitude in Arunachal Pradesh. Since 1950, country had experienced earthquake of less than 6.5 magnitude at Richter Scales.