Assessment of weathering damage on the Petroglyphs of Cheonjeon-ri, Ulsan, Republic of Korea

The Petroglyphs of Cheonjeon-ri in the area of Ulsan Metropolitan City in the southeastern part of the Republic of Korea represent outstanding cultural property of the country. The rock carvings—discovered about 40 years ago—provide valuable information on the life of the ancient people of different periods. In 1973, the petroglyphs were designated Korean National Treasure. Apparently, the petroglyphs have suffered damage from weathering such as loss of stone material, current detachment of stone material and deposits on the stone surface. The protection of this masterpiece of historic rock carving has become an important concern in the country. Geoscientific studies were carried out, targeted to stone analysis and to characterization and rating of weathering damage. The diagnostic studies combined laboratory analysis of representative unweathered and weathered stone material and in situ investigation by means of profile measurements at the carvings, mapping of weathering forms, ultrasonic measurements and rebound hardness measurements. Methodology and results of the material and damage diagnosis are presented. The results on type and extent of damage in combination with deduced risk prognosis reveal a considerable threat to the historical site of Cheonjeon-ri due to weathering and they indicate the need of intervention for monument preservation.