Chan Chan Archaeological Zone, located on the Peruvian coast near the present-day city of Trujillo, contains the ruins of the once-grand city of Chan Chan. This city was the capital of the Chimu Kingdom, which ruled a large swath of coastal Peru from 850-1470 CE. At its peak, Chan Chan was the largest city in the pre-Columbian Americas, spanning 20 sq. km. with an estimated population of 60,000 (Hathaway 2009). It was also the largest adobe city in the world at this time, and the sprawling labyrinths of earthen architecture which still exist today stand testament to the marvelous engineering of the Chimu Kingdom, which, in the 1400s, was centuries ahead of its time.
As one of the few well-preserved traces of the Chimu that we have left, Chan Chan reveals the genius of this ancient kingdom. Chan Chan is the result of very rigorous and well-planned urban development, called “an absolute masterpiece of town planning” by UNESCO, with strict zoning that enforced class segregation. The focal points of the city were nine large, palace-like areas known as ciudadelas, which were decorated extravagantly and seemed to house nobility. The working class were apparently confined to small, almost apartment-like structures which doubled as workshops, located around the ciudadelas. Further from the central areas of the arid city, evidence can be found of an ambitious irrigation system drawing water from the nearby Moche River, and even an attempt to construct a 50-mile-long canal to the distant Chicama River. Because of these structures and technologies, the Chimu Kingdom has been called the “first true engineering society in the New World” (Hathaway 2009).
Today, the ruins of Chan Chan are in a precarious position. While impressive, adobe architecture does not fare well after centuries of exposure to the elements, especially water. Chan Chan was constructed in and adapted to an arid coastal desert with little rainfall – in modern times, however, the city’s remains are threatened by rising water tables and flash flooding as regional and global climate conditions change (Curry 2009). The site’s eroding earthen walls are less structurally sound as a result, making them more susceptible to damage from the earthquakes that are common along Peru’s Pacific coast as well. Finally, as with many cultural sites in non-remote areas, Chan Chan has trouble dealing with looters and squatters, as well as fending off advancing urbanization and infrastructure from Trujillo.
The biggest threat to Chan Chan is simply that the ancient adobe structures that define the site are slowly turning to mud. This is the result of heavier-than-usual rainfall and periodic flash flooding, which has been dramatically more intense in just the past few decades. It becomes especially bad in years when the El Niño weather pattern is in effect. While climatologists still can’t say for sure, due to the complexity of factors involved in climate models, it seems that El Niño conditions are occurring with increased frequency, and the intensity of each El Niño is growing (Pearce 2016). Regardless of whether or not global warming is to blame for these changes, as many have theorized, the heavy rainfall and intense weather that each El Niño brings is a major source of erosion and a threat to delicate heritage sites on both sides of the Pacific Ocean.
Another natural phenomenon threatening Chan Chan is frequent earthquakes. A long tectonic boundary lies along the western coast of Peru, regularly generating earthquakes as the Pacific Plate subducts under the South American continent. Cuadra et al. (2010) map the foci of earthquakes at various cross sections perpendicular to the Peruvian coast, showing that, as expected from a west-to-east subduction zone, earthquakes occur shallowly in coastal areas and at greater depths as you move further inland. Shallow quakes are more likely to cause structural damage at the surface, so sites like Chan Chan that are situated right on the coast (and thus very close to the subduction zone) suffer from stronger shocks and increased structural damage when earthquakes occur. The same is true around the world – many continental margins and island arcs are situated over subduction zones, and coastal locations near those boundaries are more susceptible to quake damage. Older structures, like those found in Chan Chan, have almost always been deteriorated by age and weathering and thus are especially at risk to such structural damage.
The Chan Chan Archaeological Zone has lasting value in multiple fields, even as it crumbles away before our eyes. The race to preserve Chan Chan has presented historians and engineers with a unique challenge – unable to stop the climate patterns and tectonic forces that damage the site, they must somehow both restore the site in a culturally-appropriate manner and shield it from further harm. The usual solution for sites at risk due to exposure – namely, covering the whole site or putting a building around it – is simply not feasible on the scale of a site that is spread throughout a 20 sq. km. area. Unable to pour large amounts of funding and manpower into such construction efforts, Peruvian government officials have recruited local volunteers to help partially cover specific areas of the site, and even assist in restoration work, as a cost-effective, community-driven approach to cultural preservation (Arellano 2009).
Research is also underway in a new Earthen Architecture Laboratory (Peru Ministry of Culture 2016) to develop new methods of preserving, repairing, and waterproofing adobe structures without significantly altering their historic physical and chemical profile. This lab is also working with 3D Laser Scanning technologies to digitally preserve detailed features located in Chan Chan, such as the elaborate friezes found in many of the ciudadelas. The Earthen Architecture Laboratory is at the forefront of global research in these areas, having been applauded by UNESCO for their efforts. Such advances, especially those preserving adobe material, could be applied to the preservation of heritage sites around the world once perfected. In that sense, Chan Chan acts as a test subject for these new technologies, and has the potential to help save valuable cultural sites around the globe.
Hathaway, Bruce 2009 Endangered Site: Chan Chan, Peru. The Smithsonian Magazine. http://www.smithsonianmag.com/travel/endangered-site-chan-chan-peru-51748031/, accessed December 4, 2016. United Nations Educational, Scientific, and Cultural Organization 2016 Chan Chan Archaeological Zone. UNESCO World Heritage List. http://whc.unesco.org/en/list/366/, accessed December 4, 2016. Cuadra, C. H., Saito, T., Zavala, C. A., and Diaz, M. A. 2010 The challenges of protect historical adobe constructions in Peru. 14th European Conference on Earthquake Engineering. http://ares.tu.chiba-u.jp/peru/pdf/output/2010/201014ECEE_392_Cuadra.pdf, accessed December 4, 2016. Curry, Andrew 2009 Climate Change: Sites in Peril. Archaeology 62: Feature 2. http://archive.archaeology.org/0903/etc/climate_change.html, accessed December 4, 2016. Pearce, Fred. 2016 El Nino and Climate Change: Wild Weather May Get Wilder. Yale Environment 360. http://e360.yale.edu/feature/el_nino_and_climate_change_wild_weather_may_get_wilder/2960/, accessed December 4, 2016. Arellano, Juan 2009 Peru: Preservation Efforts in the Chan Chan Archaeological Site. Global Voices. https://globalvoices.org/2009/09/26/peru-preservation-efforts-in-the-chan-chan-archaeological-site/, accessed December 4, 2016. [Spanish language source] Peru Ministerio de Cultura 2016 Tecnología de punta en conservación e investigación de Chan Chan. Chan Chan Archaeological Complex. http://chanchan.gob.pe/utilizan-tecnologia-de-punta-en-conservacion-e-investigacion-de-chan-chan/, accessed December 4, 2016.