USGS assessments establish that magnitude 10.0 or greater earthquakes are physically impossible on Earth, as no known fault system extends the roughly 1,000–1,200 km required to release the necessary energy, with the 1960 Chile event at 9.5 remaining the verified maximum. This geophysical constraint, reinforced by subduction zone models and continuous global seismic monitoring, underpins the 99% market-implied probability for “No” with only four months remaining before 2027. Recent 2026 activity has included several magnitude 7+ events consistent with historical averages of 15–18 major quakes annually, yet none approach the threshold or show precursors like widespread strain accumulation. While an unprecedented multi-fault rupture or post-event magnitude revision could theoretically alter outcomes, such scenarios lack scientific basis and would require immediate USGS confirmation to affect resolution.