Easter Island Statue Project Official Website

Getting the Picture: Archaeological Inventory, Database Imagery, and Preservation of Easter Island Statues

Jo Anne Van Tilburg, Ph.D.

This is a condensed and edited version of an address given at the Getty Conservation Institute in October, 2004.


The Easter Island Statue Project (EISP) is an archaeological inventory designed to locate and document every monolithic stone sculpture (moai) on Rapa Nui.  Our research purpose is to amass large quantities of objective data in standardized ways, and to employ data analysis strategies that enable recognition of principle motif patterns, define the design canon and illustrate cultural norms. This paper describes three aspects of the project: the collection and maintenance of raw data, database strategy and management, and statue environmental damage and condition assessment reports.

The EISP Database

The EISP database consists of an archaeological site inventory and an interfacing image catalogue.  It is a comprehensive, interactive, searchable computer-based file of all moai data collected by Jo Anne Van Tilburg (1982-present), Cristián Arévalo Pakarati (1989-present), and their teams during archaeological fieldwork on Rapa Nui. It contains the following categories of data types: quadrant descriptions and images; site and statue GPS map locators; site and statue images; site and statue type definitions; statue measurements; site descriptions; narrative field notes; statue condition reports and a visual conservation glossary; cross-reference identifiers; political divisions; historical and ethnographic observations, and survey and excavation histories.

The database is stored on three computers, two of which are at UCLA and the other on Rapa Nui. All three are maintained, backed-up, and updated by the EISP database manager. Programs employed include Portfolio 7 for image database management, Microsoft Access and Excel for metric and other data management, and Adobe Photoshop and Illustrator for image editing. The Statdat database (1 to 55 measurements on every statue documented) is managed by the SAS statistical package.  Micro station GIS and GPS tools and AutoCAD are used for mapping data management.

Our database is broad, but it is also deep.  It also contains hands-on documentation of museum objects, including monolithic statues, stone carvings, woodcarvings, rock art, and other ritual objects directly related to moai iconography.  We have salvaged unpublished excavation records (dating from 1868 to 1960) from dozens of public and private sources.  Unpublished field notes describing excavations conducted by Katherine Routledge of the Mana Expedition to Easter Island, 1914-15, have been deciphered and filed with the appropriate statues whenever possible.  These records allow us to reconstruct stratigraphic histories of specific moai in Rano Raraku. About 190 statues were dug in Rano Raraku between 1914 and 1980, most of them  without archaeological controls or published documentation.

Supporting data include hundreds of non-EISP images and measurements of moai provided by individuals and nearly all major curatorial institutions. The Alfred Métraux photographic collection held by his estate is included, as are museum collection images donated by the descendants of Henri Lavachery, his colleague on the Franco-Belgian Expedition to Easter Island, 1934-35. The EISP database is a robust analytical research tool that is incredibly useful in integrating a vast quantity of information.  It is also critical to island-wide cultural site research, reconstruction, preservation and management.

Previous Mapping in Rano Raraku

Maps and images created by Chilean governmental agencies over three decades were reviewed in preparation for creating the published map of Rano Raraku (Cristino and Vargas 1980; Cristino et al. 1981).  A key base document was the plan of the volcano created by Lt. D.R. Ritchie of the Mana Expedition to Easter Island, 1914.  Five archaeological zones were created in Rano Raraku:  interior and exterior slopes, interior and exterior quarries, and upper exterior quarries (Vargas 1988:136).  The 394 statues recorded to 1981 were numbered, systematic measurements were taken, an attribute list was created, a typological strategy was devised, and a summary report of size and distribution was published (ibid). Two quarry zones, designated C and D, were outlined.  A detailed map was not created.

The goal of EISP’s seasonal mapping effort in the interior of Rano Raraku was to map all statues, outline the papa, and fully delineate the quarries in Areas C and D; to compile a contour map of the area showing the main topographical features, and to localize all previously mapped and numbered statues that are standing or fallen on the interior slopes.

Surveying was accomplished by J. Van Tilburg and C. Arévalo Pakarati with Dr. Peter Boniface (in 2002 and 2003), Matthew Bates (in 2004) of California Polytechnic University, Pomona, and Alice Hom.  We were supported by a team composed of UCLA Rock Art Archive staff and volunteers and Rapa Nui resident participants.  EISP field teams worked 75% of total allotted on-island field time in Rano Raraku and the balance in their Hanga Roa digital lab.  Lab tasks included field work logistics planning, equipment shakedown, data analysis, image processing, image cataloging, data importation, map drafting and design, website maintenance, and report preparation.

An existing GPS station approximately 10 km west of Rano Raraku was established by NASA in 1998.  In 2000, we placed our survey on the GPS datum WGS 84 and the UTM (Universal Transverse Mercator) projection zone 12. This is the same projection as was used for the previous survey by the University of Chile team and, therefore, provides consistent data.  We established four base stations in Rano Raraku on the south side of the volcano and marked each by steel pegs placed level with the ground. These are located away from the main path and not ordinarily visible to passersby. Another three points were established in Area C and marked by wooden pegs driven in flush with the ground. These pegs were also placed away from paths so that they would remain inconspicuous and undisturbed.

The positions of the statues in all quarries of Areas C and D were surveyed to centimeter level accuracy using two Ashtec GPS single frequency satellite receivers to gain latitude, longitude and elevation above sea level. The attitude of the statues was also recorded: the direction in which the statue faced; the forward slope, and the sideways/lateral slope.

The exact position, total length, total height above ground, compass orientation, tilt, and circumference of every non-quarry statue, standing or lying on the slopes of both the interior and the exterior of the volcano, were also recorded. Statue condition reports were completed on every one of the statues in the interior and on all of those on the exterior slopes. Digital and standard photography, sketches, and measurements as appropriate were accomplished.

In 2004, we used Trimble 5700 equipment.  Our major field emphasis was the collection of additional mapping points that would allow the further exposition of design details on selected statues and quarries.  The pace of work was approximately 300 survey points collected per day for a total of 2200 points collected in Sections C and D.

Our GPS map is supported by satellite photography of Rano Raraku in its entirety. The final purpose of our map, other than to complete Rano Raraku site documentation, is to act as a coordinating and organizing tool for the interactive presentation of the EISP image and statue inventory databases.  This goal includes, whenever possible, clarifying the historical and archaeological contexts of past excavations in Rano Raraku.

Mapping Problems Encountered

A few interior quarry features previously mapped (Cristino et al. 1981) were impossible to relocate without additional identifying information. In the case of statue RR-001-287, originally mapped and documented by the University of Chile team, this is particularly unfortunate, as the statue form is unique to the interior.  However, the EISP database contains (and displays) full metric and photographic documentation of this important object. Other confusions have crept into the mapping record.  For example, a single interior statue EISP designated RR-03C-001 and 117 by Routledge (1919: fig. 47) was shown correctly on her diagrammatic sketch as supine.  On Skjölsvold’s (1961) re-drawing of this same sketch, it is assigned the Englert (PSE) number (but, unfortunately, not cross-referenced to 117) and incorrectly shown as upright.

On the exterior slopes, eight statues or possible statues shown on the University of Chile map and numbering RR-002-209, 215, 216, 226-228, and 231-232 were not relocated due to new rock falls or erosion of identifying features.  In a few instances, we found that the orientations, head/base relationships or minor archaeological details (i.e. presence or absence of taheta) of several statues on both the interior and exterior were inaccurately indicated on the University of Chile map (Cristino et al. 1981). These anomalies will be rectified on our forthcoming map and all available identification numbers assigned statues by previous investigators will be cross-referenced.

None of the 19 individual interior quarries are directly linked, but internally some of them show a degree of planning. Some quarries appear to have been practice or teaching areas for such important features as statue heads and faces. As Routledge (1919:179) noted, narrow carving canals, some very steep and dangerous, are cut into the bedrock alongside and at the top and bottom of roughed-out blocks.  These average about 50 cm wide, and some are stepped.  Carvers stood in these canals to work.

While it has been noted by previous observers and investigators that there are discrete phases of statue carving, six basic stages or steps are, in general, universal.  The first was to shape a rectangular block.  While Routledge (ibid.) states that only “in a few cases, the stone has been roughed out into preliminary blocks,” I agree with Skjölsvold (1961: 367) that shaped blocks were nearly always the first step in the interior quarries. A shallow groove was then cut in from each side of the block at the neck. Next, the faces were carved. This is in keeping with the ritual importance of the head and face, but the elongated nose also created a midline that made it easier to take the next step:  the accurate positioning of torso details.  Undercutting the statue for removal usually began at the same time.  The last step was to brace the statue in place prior to removing it from the quarry (Skjölsvold 1961:368).

Obviously, it is easiest to apply upper surface details to a carving when it is lying in the prone position, although a few statues in the interior and exterior quarries are in lateral positions.  It is also widely agreed that the upright position allows carvers to finish and detail the backs of statues (Routledge 1919:188; Skjölsvold 1961: 369).  That is not, in my view, the full explanation for the twenty statues implanted upright in the interior slopes.

Ten upright statues in the interior were excavated by the Mana Expedition; one by the Norwegian Archaeological Expedition, and at least one (and perhaps more) were re-excavated by an unknown person at a later date. Analysis of cumulative data reveals, first, that ten of the excavated statues probably “stood free” (Skjölsvold 1961:359). In one case, Routledge (WKR RGS) describes a statue implanted in a hole dug out of solid bedrock, an obviously unnecessary and labor intensive effort if ultimate removal was intended. Secondly, while it is clear that natural debris has washed down from above on both the interior and exterior slopes, all upright statues were certainly backfilled.  This was done, I propose, in an effort to protect them, to allow them to remain standing, and to facilitate subsequent in situ ritual and burial uses. Indeed, excavation data from exterior slope statues (cf. Skjölsvold 1961; Routledge 1919) reveals that most upright statues were implanted on prepared pavements.   Thus, I agree with Routledge (1919:189), who believed that statues were “intended to remain” upright on the slopes of Rano Raraku and were not “merely awaiting removal to an ahu.”

Research Value of the Database

The value of the EISP database is that it supports reconstruction of the prehistoric Rapa Nui human population as a component of ecological, political, and esoteric systems.  It combines analytical tools with social theory to contribute a unique perspective on island change.  Its use facilitates the semiotic analysis of prehistoric Polynesian spatial organization.  It is complementary to other ecological, geographic, economic, and social analyses in Pacific Studies, and integrates Rapa Nui into the larger and better understood East Polynesian interaction sphere. Finally, it provides insight into the long-term development of human systems, allowing visualization of historical and ecological linkages of the past with the present and future.

Statue Condition Reports and the Conservation Value of the Database

Statue condition reports were completed on all statues in the database prior to 1986. These condition reports are all subjective, comparative observations of statue situation and condition.  In 2004, our condition reporting system was reviewed by members of the Getty Conservation Center staff.  As a base-line inventory with time depth, it was deemed a useful tool for conservators; however, some categories of data were revised, redefined, or renamed.  These new-format statue condition reports were then completed by 2004 team members for every statue documented in the interior slopes and quarries, and for those standing or fallen on the exterior.

Our initial, informal analysis of observational data collected on the stone surface condition of statues in virtually every part of the island illustrates a truly alarming deterioration (Table 1). Every single statue in the interior of Rano Raraku is in poor or extremely poor condition.  Every statue suffers from near-complete erosion of stone surface, and decomposition is universal.  Structural problems include delamination as well as fine, hairline cracks that sometimes widen to become deep fissures.  Statues are needlessly and repeatedly damaged by misdirected or unaccompanied tourists walking or climbing on them.  Our map contains the existing pathways used by tourists.  All but one of them negatively impact statues.

Statues standing on the interior slopes are repeatedly abraded or broken by livestock.  Mosses, and lichens in three discrete stages of growth and fertilized by bird droppings, are rampant on statue surfaces. Grass and grass seeds, in the words of one of our Rapa Nui field colleagues, are “eating the moai.” A comparison of images taken of a single statue over the 90 years between 1914 and 2004 shows weathering to near-complete loss of design detail.  Some of the statues, in fact, have passed the point of no return; the only evidence available of their former appearance is that contained in the EISP database.

Condition Problem Mitigation

Preservation of the moai may be approached in two ways:  directly, by restoring or reinforcing the stone surface, and indirectly, by controlling or mitigating natural or human environmental conditions. Volcanic tuffs, including those of the type found in Rano Raraku, are extremely vulnerable to natural weathering as well as to human destruction (Charola 1990; Van Tilburg 1990).  They have “not been studied worldwide as thoroughly” as other stone types (Charola 1990).  From 1999-2003, extensive test-treatments of Rano Raraku and other volcanic tuffs were carried out, and will be reported upon at this conference (Bahamondez P. 1990).  Various substances have been investigated as possible stone consolidates; these, too, will be reported upon. Cleaning, drying, restoring, and reinforcing the stone surface are all specialist tasks with inherent risks; selection of the statues to be treated requires consideration of each statue’s discrete condition, archaeological role, and environmental situation, as well as detailed tests.

The interior of Rano Raraku is a highly vulnerable site composed of interfacing ecological and cultural zones. Sustainable visitor management is immediately required to insure visitor satisfaction and safety, as well as site protection in perpetuity.  Two environmental issues require immediate mitigation. First, dense shrubbery (and the resultant moisture retained in the soil and released into the environment immediately adjacent to standing statues) must be controlled or eradicated.

Secondly, excessive damage is being done to the stone surfaces of incomplete statues by visitors climbing, sitting and walking upon them. It is crucial to immediately adjust the use of multiple, often conflicting or unnecessary trails, and perhaps to move visitors completely away from interior quarries. A single visitor trail, winding along the base of the interior slope in front of standing statues, will direct visitors through a more resistant or resilient area. Increased visitor education, direction, and monitoring by guides and park guards are essential.

Marion and Farrell (2001:224) discuss visitor use-related impacts in national parks in Central and South America. They demonstrate a range of rapid assessment techniques currently available for documenting the negative impact of tourism in vulnerable areas such as Rano Raraku.  They illustrate management techniques that are well-established and available to minimize negative visitor impacts, and outline a variety of means available to reduce barriers to effective visitor monitoring (including the universal problem of limited funding and staffing).


A pilot plan for the preservation of Rano Raraku as an archaeological and cultural site and the improvement of visitor services has been developed by a coalition of island agencies (CONAF el al. 2001). We strongly support this effort. We suggest that successful cultural management of the patrimony of Rapa Nui can be enhanced through input provided by archaeological research and, specifically, by the use and integration of the EISP database into conservation planning and mitigation efforts.


Sincere gratitude to the Consejo de Monumentos Rapa Nui; Pedro Edmunds Paoa, Alcalde de Rapa Nui; Corporacion Nacional Forestal (CONAF) and the Parque Nacional Rapa Nui; the Oficina Local de Turismo, Isla de Pascua (SERNATUR); the Asociación de Guias Turisticos; the Corporación Nacional de Desarrollo Indigena (CONADI).  Thanks to Sergio Rapu Haoa; Rafael Rapu Haoa; Enrique Tuki; Ema Tuki Ika;  Leslie Rainer of the Getty Conservation Institute; Claudio Cristino F. and Patricia Vargas C.; José Miguel Ramírez-A. and the Centro de Estudios Rapa Nui, Universidad de Valparaíso.

The EISP website (www.eisp.org) reports aspects of on-going fieldwork. EISP survey team members were Matthew Bates; Gordon Hull; Debra Isaac; Susana Nahoe A.; Alana Perlin; Cristián Silva A., Johannes Van Tilburg, and Bill White.  Additional field assistance was provided by Elena Mazuela H. and the Hucke family. The support of CONAF Park Guards stationed in Rano Raraku is deeply appreciated.

References Cited

Bahamondez P., M. 1990.  “Acciones de conservación sobre los moai de Isla de Pascua.  Su evaluación en laboratorio.”  In A. Elena Charola (ed.) Resúmenes presentados a la Reunión Internacional Isla de Pascua, Chile.  Santiago:  Dirección de Bibliotecas, Archivos y Museos.

Charola, A. Elena (ed.).  1990.  Lavas Y Tobas Volcanicas.  Resúmenes presentados a la Reunión Internacional Isla de Pascua, Chile.  Santiago:  Dirección de Bibliotecas, Archivos y Museos.

CONAF et al. 2001.  Plan Para Contribuir A La Conservación Del Patrimonio Turístico Cultural y Natural Del Sector Rano Raraku.

Cristino F., C. and P. Vargas C. 1980.  “Prospección arqueólogica de Isla de Pascua.”  Anales de la Universidad de Chile. Santiago:  Universidad de Chile, nos. 161-2, 191-215.

Cristino F., C., P. Vargas C. and R. Izaurieta S. 1981.  Atlas Arqueólogica de Isla de Pascua. Santiago:  Facultad de Arqitectura y Urbanismo, Instituto de Estudios, Universidad de Chile.

Marion, J.L. and T.A. 2001.  “Identifying and assessing ecotourism visitor impacts at eight protected areas in Costa Rica and Belize.  Environmental Conservation 28 (3): 215-225.

McCoy, P. n.d. Field notes [on file, Universidad de Chile, Instituto de Estudios Isla de Pascua].

Routledge, K.S. (Mrs Scoresby) 1919.  The Mystery of Easter Island. London:  Sifton, Praed.

Skjölsvold, A. 1961.  “The stone statues and quarries of Rano Raraku.”  In Reports of the Norwegian Archaeological Expedition to Easter Island and the East Pacific, Vol. 1, Archaeology of Easter Island. T. Heyerdahl and E.N. Ferdon, Jr. (eds.) Santa Fe:  Monographs of the School of American Research and the Museum of New Mexico (24), 339-380.

Vargas C., P. 1988.  “Easter Island Statue Type, Part One:  The  Moai as Archaeological Artifact.” In P. Vargas C. (ed). First International Congress Easter Island and East Polynesia, Vol. 1, Archaeology. Santiago:  Universidad de Chile, Facultad de Arquitectura y Urbanismo, Instituto de Estudios, Isla de Pascua, 133-150.

Van Tilburg, J. 1986.  “Power and symbol:  The stylistic analysis of Easter Island monolithic sculpture.”  Ph.D. diss., The Institute of Archaeology, UCLA.

1988.  “Easter Island Statue Type, Part Three:  The Moai as Socio-Political Feature.”  In P. Vargas C. (ed.) First International Congress Easter Island and East Polynesia, Vol. 1, Archaeology. Santiago:  Universidad de Chile, Facultad de Arquitectura y Urbanismo, Instituto de Estudios, Isla de Pascua,  164-173.

1990.  “Respect for Rapa Nui:  Exhibition and conservation of Easter Island stone statues.”  Antiquity 64: 249-258.

1994. Easter Island Archaeology Ecology and Culture. London:  The British Museum Press.

2003.  The Life of Katherine Routledge and Her Remarkable Expedition to Easter Island.  New York:  Scribner’s.

2005 [in press].  Hoa Hakananai’a.  London: The British Museum Press.

Van Tilburg, J. and P. Vargas C. 1998.  “Easter Island Statue Inventory and Documentation:  A Status Report.”  In P. Vargas C. (ed.) Easter Island and East Polynesia Prehistory. Santiago:  Universidad de Chile, Facultad de Arquitectura y Urbanismo, Instituto de Estudios, Isla de Pascua.

Jo Anne Van Tilburg, Ph.D. — Archaeologist; Director, UCLA Rock Art Archive, Cotsen Institute of Archaeology; Project Director, Easter Island Statue Project Conservation Initiative

Posted on May 4th, 2009 by Jo Anne Van Tilburg, Ph.D. | Category: Conservation Reports, Moai Inventory, Presentations, Rano Raraku Survey |