University of Guam faculty and graduate students study a sinkhole and karst terrain at Tarague Well 4 at Andersen Air Force Base Oct. 8. Navy environmental specialists escorted John Jensen, University of Guam chief hydrogeologist and professor of environmental geology, and Water & Environmental Research Institute Western Pacific director, and his graduate students to the area to study the unique karst at the Air Force Base. - University of Guam faculty and graduate students study a sinkhole and karst terrain at Tarague Well 4 at Andersen Air Force Base Oct. 8. Navy environmental specialists escorted John Jensen, University of Guam chief hydrogeologist and professor of environmental geology, and Water & Environmental Research Institute Western Pacific director, and his graduate students to the area to study the unique karst at the Air Force Base.