Timber Structures and Architectures in Seism Prone Areas Included in the UNESCO World Heritage List (Progress Report) Michela Semplici, Gennaro Tampone University of Florence, Dept. of Restauro e Conservazione dei Beni Architettonici A study carried out by the authors about the timber architectures and load bearing structures in the UNESCO World Heritage List evidenced, even if a very small number of ancient timber structures are inscribed, a widespread presence of this constructions in the world as well as a large number of typologies. This study showed that in many Countries and in several cases, timber structures and wooden architectures are not the object of conservation and appropriate repair and are suffering from neglect and alteration. This situation, which has been evidenced from the study of the files on the monuments inscribed in the UNESCO World Heritage List, should give rise to much concern for the possible effects of structural failure, especially for the buildings which are in seism prone areas. It must be added that, except for some recently inscribed specimens, the List is mainly based on old traditional concepts related to aesthetic and historic values only and little attention is paid to the load bearing structure; but we ought to remember the importance of the efficiency of the structural mechanism, which is the main responsible for the survival of the architectural heritage. In the seism prone areas, all over the time, man experimented a large number of structural systems to prevent injuries from earthquake and, according to experience, tried to improve the building techniques. The wooden structures, because of the lightness (related to the strength) of the material and the ductility of the connections, proved to be more efficient than other systems; this is one of the reason for their diffusion all over the world. We can tell about very simple anti-seismic constructions, like the pre-Hispanic huts and houses in Joya de Cerén, San Salvador (c. 600), or about the reconstruction of San Francisco de Lima, Peru after 1657 adopting the traditional native techniques (reeds and mud). The Portuguese Gaiola, a structural system conceived for the reconstruction of the city of Lisbon destroyed by the terrible earthquake occurred in the year 1755, as well as the Casa Baraccata of Vivenzio in Italy (after 1788), are interesting example of made-on-purpose planning of seism-resistant systems. The paper deals with the main systems documented in the UNESCO World Heritage List. 1. The “Wooden World Heritage” and the “World Heritage List in Danger” in relation to the seismic risk With the analysis of the World Heritage Dossiers kept in the UNESCO-ICOMOS Documentation Centre in Paris, we can draw up a list of the “Wooden World Heritage”. At present this does not include every timber structure or wooden architecture which is in every site inscribed on the World Heritage List, but the list of every site where the presence of timber in the structures is documented. CHINA: 1987 Mogao Caves 1997 Changdeokgung Palace AFRICA Complex 1987 Mount Taishan BENIN: 1985 Royal Palaces of 1997 Hwaseong Fortress Abomey 1987-2004 Imperial Palaces of the Ming and Qing UZBEKISTAN: 1990 Itchan Kala ETHIOPIA: 1978 Rock-Hewn Churches, Dynasties in Beijing and Lalibela Shenyang 1993 Historic Centre of Bukhara 1979 Fasil Ghebbi, Gondar 1994-2000-2001 Historic Region Ensemble of the Potala 2000 istoric Centre of Palace, Lhasa Shakhrisyabz GAMBIA: 2003 James Island and Related Sites 1994 Mountain Report and 2001 Samarkand - its Outlying Temples, Crossroads of Cultures MADAGASCAR: 2001 Royal Hill of Chengde Ambohimanga VIETNAM: 1999 Hoi An Ancient Town 1996 Lushan National Prak MALI: 1988 Old Towns of Djenné 1997 Ancient City of Ping 1988 Timbuctù Yao EUROPE (Progress Report) 1989 Cliff of Bandiagara 1997 Old Town of Lijiang FINLAND 1991 Old Rauma (Land of the Dogons) 1997-2000 Classical Gardens 1994 Petäjävesi Old Church 2004 Tomb of Askia of Suzhou FRANCE 1988 Strasbourg –Grande île MOZAMBIQUE: 1991 Island of Mozambique 1999 Mount Wuyi GERMANY 1993 Maulbronn Monastery NIGERIA: 1991 Sukur Cultural Landscape 2000 Ancient Villages in Complex Southern Anhui-Xidi and TOGO: 2004 Koutammakou, la terra Hongcun ITALY 1987 Venice and its Lagoon dei Batamarriba 2000 Mount Qingcheng and LATVIA 1997 Historic Centre of Riga UGANDA: 1994 Tombs of Buganda the Dujiangyan Irrigation Kings at Kasubi System LITHUANIA 1994 Vilnius Historic Centre 2000-2003-2004 Imperial NORWAY 1979 Bryggen ARAB STATES Tombs of the Ming e Qing Dynasties 1979 Urnes Stave Church ALGERIA: 1992 Kasbah of Algiers INDIA: 2003 Rock Shelters of 1980 Rǿros Bhimbetka EGYPT: 1979 Islamic Cairo POLAND 1978 Wieliczka Salt Mine 2002 Saint Catherine Area 2004 Chhatrapati Shivaji Terminus 2001 Churches of Peace in MAURITANIA: 1996 Ancient Ksour of Jawor and Swidnica Ouadane, Chinguetti, Tichitt JAPAN: 1993 Buddhist Monuments in the Horyu-ji Area 2003 Wooden Churches of and Oualata Southern Little Poland MOROCCO: 1985 Medina of Marrakesh 1993 Himeji-jo PORTUGAL 2001 Historic Centre of 1997 Medina of Tétouan 1994 Historic Monuments in Guimarăes the Ancient Kyoto (Kyoto, 2001 Medina of Essaouira Uji and Otsu Cities) ROMANIA 1999 Wooden Churches Maramureş 2004 Portuguese city of 1995 Historic Villages of Mazagan Shirakawa-go and Gokayama RUSSIAN 1990 Kizhi Pogost FEDERATION OMAN: 1988 Archaeological Sites of 1996 Itsukushima Shinto Bat, Al-Khutm and Al-Ayn Shrine SLOVACK 1993 Vikolínek REPUBLIC SYRIAN ARAB 1986 Ancient City of Aleppo 1998 Historic Monuments of SPAIN 1986-2001 Mudejar REPUBLIC: Ancient Nara Architecture of Aragon TUNISIA: 1979 Medina of Tunisi 1999 Shrines and Temples of TURKEY 1985 Historic areas of Nikko Istanbul 1988 Kairouan 2004 Sacred Sites and YEMEN: 1992 Old Walled City of Pilgrimage Routes in the Kii LATIN AMERICA AND Shibam Mountain Range CARIBBEAN 1993 Historic Town of Zabid KAZAKHSTAN: 2003 Mausoleum of Khoja Ahmed Yasawi ARGENTINA: 2000 Jesuit Block and Estancias of Córdoba ASIA AND PACIFIC MONGOLIA: 2004 Orkhon Valley Cultural Landscape 2003 Quebrada di Humahuaca AFGHANISTAN: 2002 Minaret and REPUBLIC OF 1995 Haeinsa Temple ARGENTINA/ 1983–1984 Jesuit Missions of Archaeological Remains of Jam BRAZIL: KOREA: Janggyeong Panteon, the the Guaranis AUSTRALIA: Depositories for the Tripitaka 1981 Willandra Lakes Region BOLIVIA: 1987 City of Potosí Koreana Woodblocks 2004 Royal Exhibition 1990 Jesuit Missions of the Building and Cariton Gardens 1995 Jongmyo Shrine Chiquitos 1991 Historic City of Sucre GUATEMALA 1979 Antigua Guatemala SURINAME: 2002 Historic Inner City of Paramaribo BRAZIL: 1987 Brasilia HAITI 1982 National Historic Park – Citadel, Sans Souci, URUGUAY: 1995 Historic Quarter of the 1999 Historic Centre of the Ramiers City of Colonia del Town of Diamantina Sacramento MEXICO 1987 Historic Centre of CHILE: 2000 Churches of Chiloé Mexico City and Xochimilco VENEZUELA: 1993 Coro and its Port 1987 Historic Centre of 2003 Historic Quarter Puebla of the Seaport City of NORTH AMERICA Valparaíso 1991 Historic Centre of Morelia CANADA: 1978 L’Anse aux Meadows 2005 Humberstone and Santa National Historic Site Laura Saltpeter Works 1998 Archaeological Zone of Paquimé, Casas Grandes 1981 SGaan Gwaii (Antony 2006 Sewell Mining Town Island) 2003 Franciscan Missions in COLOMBIA: 1984 Port, Fortresses and the Sierra Gorda of Querétaro 1985 Historic District of Group of Monuments, Québec Cartagena 2004 Luis Barragán House and Studio 1995 Old Town Lunenburg 1995 Historic Centre of Santa Crux de Mompox NICARAGUA: 2000 Ruins of León Viejo U.S.A. 1978 Mesa Verde CUBA: 1982 Old Havana and its PANAMA 1980 Fortifications on the 1979 Independence Hall Fortifications Caribbean Side of Panama: Portobelo-San Lorenzo 1982 Cahokia Mounds State 1988 Trinidad and the Valley Historic Site de los Ingenios 1997 Archaeological site of Panamá Viejo and Historic 1983 La Fortaleza and San 1997 San Pedro de la Roca District of Panamá Juan Historic Site in Puerto Castle, Santiago de Cuba Rico PERÙ: 1983 City of Cuzco 1999 Viñales Valley 1987 Chaco Culture National 1983 Historic Santuary of Historic Park 2000 Archaeological Machu Picchu Landscape of the First Coffee 1992 Pueblo de Taos Plantations in the South-East 1986 Chan Chan of Cuba Archaeological Zone EL 1993 Joya de Ceren 2000 Historical Centre of the SALVADOR: Archaeological Site City of Arequipa Among the sites listed above only 6 are included on the List of World Heritage in Danger in accordance with Article 11 of the Convention of 1972. Among these 6 sites which are highlighted in grey on the list above, no one has been included on the List of World Heritage in Danger because they are at risk of earthquake. Is it a simple coincidence or maybe it is a demonstration that timber structures in many cases perform their duties in a satisfactory way? 2. The Wooden World Heritage in the Zones of Global Seismic Hazard The purpose of this study is to analyse the value given to the anti-seismic wooden structures in the World Heritage as a mechanism. The first step to achieve this result is the research of the areas in the world with the highest level of seismic risk and the second is the analysis of the World Heritage Dossiers where we have found plenty of documented wooden architectures. The Global Seismic Hazard Map is the result of a demonstration project: “The Global Seismic Hazard Assessment Program” (GSHAP) of the UN/International Decade of Natural Disaster Reduction conducted in the 1992-1998 period. “Seismic hazard is defined as the probable level of ground shaking associated with the recurrence of the earthquakes. The assessment of seismic hazard is the first step in the evaluation of seismic risk, obtained by combining the seismic hazard with vulnerability factors (type, value and age of buildings and infrastructures, population density, land use, date and time of the day).” Fig. 1 The Global Seismic Hazard Map The cooler colours represent lower hazard while the warmer colours represent higher hazard.