This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When Pliny the Younger recorded his firsthand experience of the eruption of Mount Vesuvius 2,000 years ago—a cataclysm that buried Pompeii and killed his uncle, Pliny the Elder—he provided enough detail about the date to allow scientists to benchmark methods for dating volcanic eruptions. In a study to be published this week in the journal Science Advances, scientists from the Berkeley Geochronology Center, UC Berkeley and the University of Padua in Italy report that argon-argon dating calibrated with the inferred date of the eruption—Aug. 24, 79 CE—is now significantly more precise, making it one of the most versatile dating methods available.
The improvement will allow geologists, paleontologists and archaeologists to attach more accurate dates to geologic events of the past, including eruptions of volcanoes that still threaten densely populated areas like Mexico City, Naples and Yogyakarta in Indonesia. It will also help ground-truth other dating methods, such as carbon-14 dating of organic material and uranium-lead dating of billion-year-old rocks from the early days of Earth. "If you want to put together the eruptive history of a volcano in relatively recent time, precision and accuracy really count," said study leader Paul Renne, a Berkeley professor in residence of earth and planetary science and director of the independent Berkeley Geochronology Center.
"The study shows that you can achieve that kind of highly useful precision and accuracy into the historical realm." Accuracy refers to whether a result is correct, whereas precision measures how reproducible the result is. The recalibrated argon-argon dating method, used on eight samples of a potassium-containing volcanic mineral from Vesuvius called sanidine, pegged the eruption at 1,938 ±13 years before the minerals were analyzed in 2025. The actual age of the volcanic minerals was 1,946 years, according to an analysis of Pliny the Younger's writings.
The estimate is equivalent to a precision of 0.7% and an accuracy of 0.4%. "This lets us more precisely infer causality between events in the geologic record, for example a meteor impact structure and a mass extinction," Renne said. A decade ago, Renne used argon-argon dating to provide precise dates for a meteor impact, volcanic eruptions in India and the dinosaur extinction—all of which took place within a few tens of thousands of years 66 million years ago.
These precise dates bolstered the idea that the impact triggered intensified volcanism, providing a one-two punch that led to the extinction of all non-avian dinosaurs. Thanks to a deep dive into the recorded history of Vesuvius' eruption by graduate student Caroline Hasler, the team was also able to validate the eruption date attributed to Pliny the Younger—Aug. 24—to within two months. This enabled the team to measure more precisely the half-life of the decay of potassium-40 to argon-40 that provides the basis for argon-argon dating.
That half-life is now 12.044 billion years, give or take 0.088 billion—twice as precise as the previous value determined from nuclear physics. Renne and his team had previously analyzed sanidine from pumice ejected during the 79 CE eruption to ground-truth argon-argon dating. Based on that 1997 analysis, they predicted that they could do better, getting the precision down to less than 1%.
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