A minaret of the Taj Mahal, the UNESCO World Heritage site in India, is tilting, according to the latest affidavit filed by the Archaeological Survey of India (ASI) in the Supreme Court. However, the tilt is within permissible limit of geodetic accuracy, says the affidavit.
ASI director general Gautam Sengupta has told the apex court that the tilt magnitude for the spike of the south-west minaret has shown increasing trend when compared with the previous studies. South-west minaret remained quite stable till 1976-77 but during the past three decades, the magnitude of tilt for spike centre increased about 3.57 cm in 2009-10 compared with 1976-77, said the affidavit.
It has been noticed that differences have slowly moved from positive to negative values over the period of time and 2011-2012 observation have shown the same trend and recorded almost the same height difference as compared to last observation epoch of 1994-95. Hence, there has been no significant change in heights of points which are lying outside the main structure during the latest epoch, the affidavit added.
On the north-east (NE) minaret, the affidavit stated, The tilt of the top centre of NE minaret in 2012 is 0.52 cm when compared with the initial values for the top observed in 1977.
On the main structure the affidavit stated, It can be inferred that the structure has remained quite stable in elevation from 1941 to 2011.
In order to monitor the behavior of the structure more closely, the ASI has requested the Supreme Court that the survey studies, along with GPS observation on all the important structures of Taj Mahal complex, should be done every year for next few years.