Overview
- The paper, published Friday, Sept. 25, 2026, anchors argon‑argon dating to Pliny the Younger’s eyewitness account of Mount Vesuvius and validates the August 24, 79 CE event to within about two months.
- Researchers reanalyzed eight potassium‑rich sanidine samples from Oplontis that Andrea Marzoli collected in 1998 and had long been shelved, using modern mass spectrometers and irradiation methods.
- When tested against the known eruption date the recalibrated method produced 0.4 percent accuracy and 0.7 percent precision and returned a K‑40→Ar‑40 decay parameter estimated with twice the prior precision.
- Argon‑argon dating infers age from potassium‑40 decay to argon‑40 in minerals like sanidine and works best on early, potassium‑rich pumice because potassium concentrates in the first erupted magma.
- The authors propose using this benchmark to recalibrate radiocarbon and other dating systems and to sharpen eruptive chronologies for volcanoes that threaten large cities, which could change hazard timelines and archaeological chronologies.