Former Chief Engineer and Secretary, PWD and one of the most respected engineers of the state N K Datta has responded to the news item regarding the earthquake threats that Dharmanagar is facing. He has written on the matter and advised the public and the government that all new constructions should conform to relevant BIS codes across the state. Municipal authorities shall have to enforce it. He has also advised that existing important government buildings shall have to be retrofitted to withstand seismic forces. Er Datta has also pointed out that Tripura is very close to the Srimangal fault and added that the state has experience of retrofitting. He also said that despite the threat none should panic but follow the rules. The octogenarian is presently in Bangaluru.
Earthquake damages in Tripura.
N K Dutta
After retirement from PWD, I got interested in Disaster Management and made many ppt presentations. I collected many relevant information in the matter. Unfortunately while leaving Agartala in a stretcher, I left everything at the Agartala home and by this time everything must have been destroyed. I have to depend on my memory.
PIC OF OLD PALACE
Dharmanagar is situated on the southern side of Shillong plateau. On June 12, 1897 there was a great earthquake with epicentre at Shillong. It was reported to be of magnitude M 8.7 and considered as the greatest earthquake in India. Later the magnitude was revised to Mŵ 8.2 to 8.3. A portion of Shillong Plateau rose violently by about 11 metres. In 1897, Dharmanagar had, perhaps, no RCC/ masonry building.
Damage in Tripura was mainly in Agartala. The Palace was completely razed to the ground. In 1900, Poet Rabindranath Tagore visited for the first time in Tripura on the invitation of Radhakishore Manikya. As the Palace was completely desroyed, Tagore was accomodated in the newly constructed house of Col. Mahim Chandra Devbarman. There was no other major building damage.
The greatest earthquake in India occurred at the India- China border on August 15, 1950 with magnitude of Mŵ 8.6. I remember about the earthquake. There was not much damage in Tripura.
In 1918 a devastating earthquake occurred in Srimangal, Sylhet. The magnitude of the earthquake was M 7.6. As the Srimangal fault is quite close to Tripura, the damage was high in Tripura. During the earthquake the Pushpavanta Palace, Kunjaban, was under construction. The first floor was so badly damaged that it had to be reconstructed.
Assam to Chittagong railway line was badly damaged. Mr. R.D. Oldham. Superintendent, GSI (present designation is Director General GSI) travelled from Assam to Chittagong in manually pushed wheel car along the rail track. The railway track was twisted in many places especially in Rangpur. Mr. Oldham stopped at places and collected information about damages around the places. There is mention about Juri, Dhalai etc railway bridges. From Akhaura he collected information about damages in Agartala and other places around. The findings of Dr. Oldham and his successor Mr.Murray Stuart are available in the Memoirs of the GSI.
Dharmanagar, situated on the south of Shillong, is not far from Shillong Plateau. Dharmanagar is situated between the Dauki fault and the Madhupur fault in Banladesh. Srimangal fault is also quite close to Tripura.
According to data collected by Dr. Oldham, there were many cases of soil liquefaction around Agartala. There were sand spouts at several places. Bed of some tanks rose by few feet. There were widespread damages around Comilla and Chittagong.
The soil in Tripura plains consists mainly of silt and fine grained soil. The water table is high in plain ( lunga) areas. These soils are highly vulnerable to soil liquefaction. This aspect has to be specially investigated while taking up any important construction in Tripura especially in North Tripura due to proximity of faults. In other words, the soil investigation should specially include the chances of soil liquefaction.
RETROFITTIG DONE/ BEING DONE
Ujjyanta Palace, Neer Mahal, MBB College have been retrofitted and UK Academy partly retrofitted. (Presently the UKA is in priority list)
Retrofitting process is on for Pushpabanta Palace (old Raj Bhawan). Six vulnerable bridges including Jahar bridge and Astabal bridge works have been taken up and target is one year
In a pilot project of NDMA four buildings Mandai bazar HS School, Ranirbazar PHC, Netaji Chiwmuhani PWD office and Melaghar Girls HS school have been retrofitted
As many as 28 DPRs have been prepared for more 28 buildings and out of them Gandachara sub div hospital and AGMC super specialty block to be retrofitted soon. As these retrofitting activities are cost intensive the state government has requested Union government for funding while with state govt funding whatever possible priority buildings are being taken up for retrofitting in phases.
( This news was also published in the Tripura Times)
