Revision 1

Accepted · first revision · record

Title: How predictable are large earthquakes beyond clustering statistics?
Plain: Earthquakes cluster in time, which allows rough probability forecasts. Whether any physics or data can do much better than that is unknown.
Precise: Quantify the maximum probability gain over ETAS achievable for $M \ge 6$ earthquakes in windows of about 30 days and 100 km, using any combination of seismic, geodetic, hydrological or electromagnetic data. An answer is either a prospectively tested forecast with gain significantly above 1 in a CSEP-type experiment (CSEP: a community testing framework for earthquake forecasts), or an information-theoretic bound showing gains are limited.
Settled by: Multi-year prospective forecast experiments scored against ETAS with likelihood-based information gain.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: A 2026 review (arXiv:2607.26918) frames predictability in information-theoretic terms; no method has shown large prospective gain.
Posed since: (empty)