POTSDAM — Frank A. Revetta, the north country’s preeminent voice on earthquakes and geophysics for more than half a century, died Sunday. He was 96. Revetta mapped the subterranean gravity patterns of New York and Pennsylvania over his career, nurtured a growing geology program in Potsdam, and was a teacher and friend to anyone. His beloved astronomy shows at the SUNY Potsdam planetarium continued until the COVID-19 pandemic began in 2020. The planetarium, which bears his name, turned 60 this year.