**USGS analysis establishes that magnitude 10 or larger earthquakes cannot occur**, as no known fault is long enough to generate the required rupture—such a feature would need to span most of the planet. This geophysical limit underpins the 98.7% market-implied probability of “No” before 2027, consistent with the instrumental record’s 9.5 maximum from the 1960 Chile event on a roughly 1,000-mile fault and the absence of any larger quake since. Plate-tectonic constraints and continuous USGS monitoring reinforce trader consensus that current stress accumulation and fault geometries cannot produce the necessary energy release in the remaining timeframe. While theoretical models allow for extreme events over geologic timescales, no realistic near-term development—such as revised magnitude scales or unexpected rupture dynamics—alters the established upper bound.