This project, supported jointly by the Petrology and Geochemistry (EAR) and the Americas Program (OISE), will focus on elements of the eruptive activity of the El Chichon volcano in Mexico. The project plan seeks to better constrain the effects of magma injection and the time between injection and eruption activity over the past 8,000 years. At El Chichon, these investigations will involve studying the effusive volcanic products exposed at the volcano in order to identify any separate magma batches, detect closed- versus open-system magmatic behavior, track magma bodies and their interactions through time, and identify changes in magma storage conditions (pressure, temperature, volatile contents) through time. These objectives will be met by analyzing stratigraphically controlled samples for argon isotope, and combining those with textural, and compositional variations in single mineral crystals, to determine magma conditions at the time of eruption. A more detailed analysis of the evolution and eruptive history of El Chichon activity will allow a better understanding of the relationships between magma systems and resulting eruptions of this Mexican volcano. Such understanding will enhance our ability to forecast its future eruptive behavior. This project is a collaborative project between the University of Alaska Fairbanks, University of Texas at Austin, and the Universidad Nacional Autonoma de Mexico and will support graduate students and scientific exchanges between the three institutions.