Previous Research
Comprehensive studies
The only previous comprehensive studies of the volcanoes of the Central Andes were those carried out in preparation of the Catalog of Active Volcanoes of the World , produced under the aegis of the International Association for Volcanology and Chemistry of the Earth's Interior (IAVCEI). Only 1,000 copies were printed, with publication costs supported by a grant from UNESCO. The Central Volcanic Zone of the Andes is covered by entries in two parts, part XV (the Chilean continent) by Casertano (1963), and Part XIX (Colombia, Ecuador and Peru) by Hantke & Parodi (1966). There are no entries at all for volcanoes in Bolivia or Argentina. Catalog entries follow a standard format, which consists of physical data (locations, heights etcetera); a description of the form and structure of the volcano; a summary of any known historic activity; a review of petrographic and petrologic data; and a bibliography. Most entries also include a sketch of the volcano. Since so little was known about the history of the volcanoes, most entries are brief. For example, the entire entry for the massive Nevado Ojos del Salado complex, the highest volcano in the world, consists of less than 100 words of text. In most cases, historic records of activity are absent. Where records are cited, these are drawn from earlier literature or are anecdotal, and are of uncertain reliability. Only one major historic eruption is documented, that of Huaynaputina, Peru in 1600 AD (VCA section 3.1.1). This great eruption took place sufficiently close to the major city of Arequipa for its effects to be devastating there. The existence of morphologically similar volcanoes and pyroclastic deposits which were hitherto undescribed, such as those of Cerro Quemado, Bolivia (VCA section 3.1.1) suggest that comparable eruptions could have taken place in unpopulated areas within historic times, and gone unrecorded.
A further source of data on Central Andean volcanoes are the Data Sheets on the Post-Miocene Volcanoes of the World (IAVCEI, 1973) but this compilation is incomplete and of limited value.
Studies of individual volcanoes
While there are many references to individual volcanoes in regional studies, such as Brüggen's Geology of Chile (1950); Ahlfeld and Branisa's Geology of Bolivia (1960) and Turner's review describing the geology of the Argentinian puna (1970), few detailed studies have been made previously. Most of these are cited where appropriate in the text. In Peru, the most noteworthy study was that of Bullard (1962) who carried out fieldwork on volcanoes near Arequipa during an extended stay in that city. He drew attention to the great eruption of Huaynaputina (VCA section 3.1.1), which was previously almost entirely unknown outside Peru. In Chile, the most detailed previous study was that of Katsui and Gonzalez (1968) who mapped and described Parinacota volcano (VCA no. 10), close to the frontiers with Peru and Bolivia. During the 1960s, a group from University College, London, led by S.E. Hollingworth initiated work on the uplift of the Andes in the area east of San Pedro de Atacama, and made valuable contributions to the geochronology, volcanology and glaciology of the area (Hollingworth, 1964; Hollingworth & Guest, 1967). A seminal study was that of J.E. Guest (1969) who published the first descriptions of some of the extensive ignimbrites on the Chile/Bolivia border. This work was followed up by a group from Imperial College, London (i.e. Francis et al., 1974) and later from the Open University (P.W. Francis & co-workers), which studied the volcanoes between 21ºand 22ºS, carried out extensive reconnaissance geochronological studies, identified most of the large silicic calderas in the region (e.g Kari Kari, Bolivia, and Cerro Galan, N.W. Argentina; VCA section 4) and made detailed petrological studies of some selected centers (e.g. San Pedro volcano, north Chile VCA no.20). This group also initiated the remote sensing studies of which Volcanoes of the Central Andes is but one result.
Geologists of the Chilean Servicio de Geologia y Mineria (formally the Instituto de Investigaciones Geologicas) have mapped large parts of the remote and inhospitable Atacama puna, and have visited many volcanoes in the course of their regional Survey work over many years. Their work is published in mainly in the form of Survey Memoirs, and in journals such as the Revistas de la Geologia de Chile. There are few published accounts of individual volcanoes in north-west Argentina or Bolivia, at least from a volcanological point of view, although an increasing volume of petrological work and studies related to mining geology have been carried out over the last decade. Coira et al (1982) have published a valuable review of the tectonic and magmatic evolution of the Andes of northern Argentina and Chile, and there are numerous other papers of a regional nature in publications of the Servicio Geologico Naçional and in journals such as the Revista of the Asociacion Geologica Argentina.. Similar regional studies are available in Memoirs and other publications of the Servicio Geologico de Bolivia (GEOBOL).