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Photo courtesy Kristi Wallace
Kristi Wallace, a geologist for the Alaska Volcano Observatory, studies ash from eruptions in the prehistoric past. Volcanic ash, or tephra, can tell us a lot about volcanoes—how big their eruptions were, and when each eruption occurred. Tephra can also be dangerous—ash from Mt. Vesuvius buried the Roman city of Pompeii.
Wallace starts her work with a helicopter ride over an active volcano, looking for spots where streams have exposed earlier ash beds. She takes samples back to her lab to determine their age and composition. This information helps her compile a picture of Alaska’s volcanic past.