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In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest Global Positioning System (GPS) campaign in the world to date (Table 1). 43 GPS receivers collected approximately 590 station-days of data in America, Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA UNO, an acronym for Central and South America -- and uno is the Spanish word for one, designating first epoch measurements. The CASA UNO experiment was the first civilian effort implementing a global GPS satellite tracking network.

Scientific goals of the project include measurement of strain in the northern Andes, measurement of subduction rates for the Cocos and Nazca plates beneath Central and South America, and measurement of relative motion between the Caribbean plate and South America. A second set of measurements are planned in 1991 (CASA DOS), and should provide preliminary estimates of crustal deformation and plate motion rates in the region. The CASA series of experiments are intended to be carried out over at least one decade.