THE KOREAN JOURNAL OF QUATERNARY RESEARCH Vol. 22, No. 2, p. 1-5 (December. 2008) The geomorphic characteristics of Bulguksa-region and the earthquake resistant structure of the Bulguksa-Temple Sangill Hwang1 1Department of Geography, College of Social Sciences, Kyungpook National University, Korea ([email protected]) Abstract Some reverse fault lines pass through the alluvial fans and west hill slope of Bulguksa mountains including Mt. Toham in the directions of N-S and NW-SE. The study area is known as relatively unstable, because of active faults. Assuming the record of earthquake in the Samguksagi, the architects in the construction of the Bulguksa temple should have recognized the possibility of breakdown from the earthquakes and the need for an unique structure against at that time. Against earthquakes, Greavee technique, a stonework construction technique following woothe one and use of Chushouok (Dongtleouok or Chumchaouok) were applied for the construction of Bulguksa temple. By designing the foundation stone with hole, a structure is prevented from motiff Ction that pillarsakdcede from a foundation stone in spite of horizontal load of earthquake while woot construction isaktrong frame at earthquake. The Bulguksa-temple isausually evaluated to be a beautiful architecture from the appeaultces like the weight balltced structure with unique decoration. ampressive architectures are beautiful in balance and harmony coming from the important and specific rolls in its own way by each part of whole structure. This beauty comes from the science. Key Words : the Bulguksa-temple, fault lines, the earthquake resistant structure, Grengee technique, Chuduseok (Dongtleseok or Chumchaseok). 1. Introduction data have reported the region as the epicenters of earth- quake (KMA, 2001). Including the Bulguksa-temple region, Ulsan (or The Bukgulsa-temple is a construction of the Bulguksa) Faults system passes through from TolilSilla Danasty and has eight national treasures and Gyeongju-si to Ulsan-si. The faults are active faults one treasure. The most impressive constructions to visit- composed of a number of reverse faults parallel to ing people are stylobate stoneworks at the front of the others (Yoon and Hwang, 1999; Okada et al, 1998). Daeungjeon, Cheongungyo-bridge, Baekungyo-bridge, According to the historical records of Samguksagi, Chilbogyo- bridge and Yeonhwagyo-bridge. These have there are many earthquake events at Gyeongju during unique construction structures different from the other the ancient time. Gyeongju was also one of the frequent stone constructions in Korea. occurrence areas of earthquake during the Joseon The stylobate stoneworks at southern and western Dynasty (Yoon et al., 2001). The recent earthquake parts of the temple were constructed using natural and - 1 - The geomorphic characteristics of Bulguksa-region and the earthquake resistant structure of the Bulguksa-Temple artificial stones with various methods. There is no dis- cluded in the construction and characteristics of architec- cussion about whether the construction structures were tural design focused on the stylobate stoneworks of for the beauty of construction, or for the other purposes. the Bulguksa-temple, and analyzes the relationship be- The paleo-architecture and art history has reported the tween the construction structure of the Bulguksa-temple construction methods and meanings of the stylobates. and geomorphic characteristics of the region focused However, these studies are not logically analyzing and on the earthquake resistant design. For these, this study discussing by scientific views, but inferring the mean- classifies the geomorphic surface around the ings by intuition and experience. Bulguksa-temple and estimates the relationship between In other words, there is no answer about the below the construction structure of the stylobate stoneworks questions; of the Bulguksa-temple and distributional characteristics 1. Why were the unique construction methods ap- of faults. plied? 2. Which mechanisms were the methods possible 2. The geomorphic characteristics of the to the earthquake resistant? Bulguksa-temple region Therefore, it is difficult to explain the real mean- ings of the construction structure and ultimate purposes. Fig. 1 shows topography around the Bulguksa-tem- At the time of understanding a cause-result relation- ple region. Confluent fans along piedmont of mountains ship between the construction structure of the are horizontally well developed. Bulguksa-temple and the geomorphic characteristics at the region, and intention of architects, we can only accept it as a work of art having scientific basis. This study examines the scientific structures in- Fig. 1. The topography around the Bulguksa-temple The topography has been formed related to moun- region(★ the Bulguksa-temple) tain environments such as the distribution of faults, characteristics of bedrock and tectonic movement, and - 2 - Sangill Hwang the Quaternary climatic change. N-S and NW-SE direc- (village), Jinhyeondong 0.9 km apart from the tion faults formed by compressive press from east and Bulguksa-temple with S direction, the fault outcrops north-east part pass through Gyeongju-Ulsan region, are found. A small river runs at the Bulguksa-temple as well as the Bulguksa Mountains. Therefore, the west- and Seonwon. Even though a river bed of the river ern slope of the mountains is very steep. The fans is composed of gravel, the river bed 10m apart from were developed at the front of the mountains during the point with east direction is composed of bedrock the glacial period. of granite and a reverse fault is found (Fig. 3). The Fig. 2 shows distribution of the geomorphic surfaces fault line has important meanings due to the possibility and fault lines at the Bulguksa-temple. 4 faults and passing the inside of the Bulguksa-temple. At Tapgol outcrops are found around the Bulguksa-temple. At (Tap-village) 0.7 km apart from the Bulguksa-temple river bed between the Bulguksa-temple and Seonwon, with WNW direction, a reverse fault is also found (Fig. Tapgol (Tap-village) 0.7 km apart from the 4). The fault of NNW-SSE direction strike passes Bulguksa-temple with WNW direction, Mudeomgol through near the inside of the Bulguksa-temple. Fig. 2. The topography of the Bulguksa-temple - 3 - The geomorphic characteristics of Bulguksa-region and the earthquake resistant structure of the Bulguksa-Temple Overall, while the northern part is high, the southern part dissected valley pass through is low altitude. Because a Buddhist temple was founded using high, middle and low surfaces of alluvial fans with different altitude from river bed, steps and stylobate stoneworks were constructed between the geomorphic surfaces. At the boundary of middle and low surface, steps and stylobate stoneworks such as Cheongungyo-bridge, Baekungyo-bridge, Chilbogyo- bridge and Yeonhwagyo-bridge were constructed. 4. The special architecture structures of the Fig. 3. The fault outcrop at point A between the Bulguksa-temple Bulguksa-temple and Seonwon The special construction structures at southern and western part of the Bulguksa-temple are Grengee techni- que, special structure named Gyeolgu, Chuduseok (Dongtleseok or Chumchaseok). 1) Grengee technique The technique has been applied to between post stone and upper wood column in Korean traditional architecture structure. The technique is that a post stone supporting a column in wood building is used as natural shape not facing the stone smoothly, and bottom of the wood column is shaved for closely contacting to the natural shape of the post stone. The reshaped wood column will be closely contacted to the post stone by load pressure of the building. Therefore, the building can maintain the original structure even in various impact. The buildings the technique were applied at the Bulguksa-temple are the left and right stylobate stoneworks of Baekungyo-bridge, stone stand (?) of Fig. 4. The fault outcrop at point B of Tap-village, Seokgatap-tower, and the stylobate stoneworks of north-western part of the Bulguksa temple Sumibeomjonggak (one of the buildings at the Bulguksa-temple). 3. The geomorphic characteristics of the Bulgulsa-temple architecture space 2) Special structure named Gyeolgu The special structure named Gyeolgu is organ- The Bulguksa-temple was founded on ranging from ization of elements composing of the building. In other high, middle to low surfaces of alluvial fans (Fig. 2). words, the vertical, horizontal and other elements should - 4 - THE KOREAN JOURNAL OF QUATERNARY RESEARCH Vol. 22, No. 2, p. 6-11 (December. 2008) be organized with the others for constructing the build- ing, and the methods or shapes of the organization is Gyeolgu. Fig. 6. The stylobate stoneworks at front of Namhoerang, Geukrakjeon (redrawn from Jang (1996)) Fig.5.The stylobate stoneworks at front of Namhoerang, Daeungjeon, Bulgulsa (redrawn 5. The meaning of earthquake resistant structure from Jang (1996)) of the Bulguksa-temple The Bulguksa-temple has a creed symbolic system 3) Chuduseok (Dongtleseok or Chumchaseok) of Buddhism. Coomaraswami said in "Dance of Siva" The most parts founded by artificial stone among that the art without science is nothing. The studies stylobate stoneworks at the Bulguksa-temple are or- of paleo-architecture and art history do not understand ganized with the others, and the most interests are all scientific meanings of the Bulguksa-temple Chuduseok (Dongtleseok or Chumchaseok). The buildings. Even though the region has the possibility