[3] Fierstein's research in geology has advanced the understanding of volcanism in Chile, including the history of Laguna del Maule.

She is also known for giving engaging presentations to teach communities about her geologic work,[8][9] including co-leading an interpretive hike at Devils Postpile National Monument in 2016.

[18] Early in her career, Fierstein wrote articles on topics in Katmai, including the Valley of Ten Thousand Smokes and the volcano Novarupta.

[28] Fierstein's work has also been applied alongside the research of Bernard R. Hubbard for determining the geologic history of the area around Mount Aniakchak.

[33] Fierstein has contributed to geologic research in both the Mojave National Preserve and the Mono Basin of California.

[39] Fierstein and Hildreth were also the first to research the stratigraphic structures making up Mount Adams in Washington and monitor the geologic changes at the mountain.

Tucker assisted in collecting samples for Hildreth and Fierstein at Mount Baker in the 1990s for a 2003 publication on its eruptive history.

[46] Also in collaboration with Hildreth, she won the Outstanding Publication award from the Association of Earth Science Editors.