Is an earthquake's final magnitude determined in its first seconds?
In plain words
A small and a giant earthquake may start out looking identical. Whether the first seconds of shaking already reveal how big the quake will get decides how useful early warning can be.
Precise statement
Using global catalogs of source time functions, determine whether the moment-rate function in the first few seconds statistically predicts the final moment magnitude $M_w$ for large events (weak or strong determinism), or whether growth is universal until arrest. An answer is a statistically significant discrimination of final $M_w$ from early moment rate, with stated scatter, or proof of indistinguishability.
What would settle it
Analysis of near-field and teleseismic source time functions of many $M \ge 7$ events with uniform processing.
Status in the literature
Unverified note
Meier and coauthors (Science, 2017) reported universal initial moment-rate growth for large subduction earthquakes, while other source-time-function studies report weak determinism; contested as of 2025.