Gyeongju earthquake boosted the tilting speed of Cheomseongdae

Gyeongju earthquake boosted the tilting speed of Cheomseongdae. September. 19, 2016 07:14. by 김상운 기자sukim@donga.com. The earthquake in Gyeongju sank Cheomseongdae Observatory by 20 millimeters. Considering that the observatory is tilting at 1 millimeter each year, 20 millimeters equals to 20 years of tilling. Experts say that it does not mean an immediate collapse of Cheomseongdae, but nothing is for certain. The Gyeongju earthquake leads people to question about whether stone cultural properties are resistant to earthquakes and people point out the need to review the response to earthquake of such assets.

The National Research Institute of Cultural Heritage under the Cultural Heritage Administration says that the central axis of Cheomseongdae is tilting toward the north by 1 millimeter per year as the ground to the north has subsided. With an additional 20-mm tilting due to the earthquake this time, the center axis sank by 224 millimeters or 1.2-degree angle.

Also, the distance between stones of the tower is further widening as the lower part of ground subsides irregularly. According to the institute's 2011 report on the safety management plan for stone cultural properties, an average of 19-mm gap was found in all layers excluding the top. The heritage agency said that each stone was separated by 1-5 millimeters besides the ones constituting the top whose shape when viewed from above is that of the Chinese character 井 after the earthquake.

Many people point out the need to provide measures to ensure the structural safety of the tower. The agency says that there is a need to review the option to disassemble the tower for restoration. Seokgatop, which the National Research Institute of Cultural Heritage disassembled for restoration in 2012 and completed the repair work in August 2016, was not damaged by the earthquake thanks to the seismic design. As for Dabotap, of which staircase stones were subsided due to the earthquake, the member of framework is expected to be replaced with a new material. The stone pagoda was last repaired during the period of Japanese occupation.