John Zayac is a Level II PhD student in the Earth and Environmental Sciences Program. A native to California, John earned his B.S. in Earth Science from the University of California, Santa Cruz and his M.S. in Geological Sciences from the University of California, Santa Barbara. He relocated to New York City three years ago and is currently living in Brooklyn.
John’s dissertation research seeks to characterize the mechanisms that cause volcanic systems to go critical, triggering an explosive eruption. In October of 2016, he conducted a field research campaign in Nicaragua focusing on large, prehistoric eruptions of Volcán Cosigüina. The most recent eruption of Cosigüina, in 1835, was six times larger than the 1980 Mount St. Helens eruption. The eruption was well documented and dispersed ash across Central America, potentially as far away as Colombia and Jamaica. Locally, the eruption was devastating, sending hot, dense clouds of ash and debris called pyroclastic flows down its slopes.
Using fine-scaled stratigraphy, John is applying a combination of field and analytical methods to study the state of the magma reservoir immediately prior to and during past eruptions in order to determine the potential eruption triggers. The identification and understanding of eruption triggers is important to monitoring volcanic systems and to assessing the hazards associated with them.
There were three major factors that led to John’s decision to pursue his PhD at the Graduate Center. First was the opportunity to tackle this Cosigüina project with his advisor, Professor Marc-Antoine Longpré. Second, was the multidisciplinary nature of the Earth and Environmental Science Program. The program encompasses a wide range of disciplines, including human geography, urban environmental science, and classical geology making it a good home for intellectually curious students. The flexibility of the curriculum has also allowed John to take advantage of several amazing opportunities, such as attending a weeklong workshop on instrumentation at UCLA and participating in a three-week NSF Chief Scientist training cruise from Honolulu to San Diego aboard the R/V Sikuliaq in December of 2016. The link to the greater CUNY system was the third major factor in his decision. Prior to moving to New York, John worked as a community college geology professor in Los Angeles, California. When choosing a university in which to pursue his PhD, John wanted to ensure that he would continue to have the opportunity to teach and mentor undergraduates in a diverse, public institution.
After graduation, John intends to seek out a faculty position at a public college or university where he can continue to combine his passion for delivering quality, undergraduate STEM education with his unending curiosity about explosive volcanic systems. 
