κ–Fusion for Earthquake Early Warning: Fusing Pre-seismic Magnetic Precursors with Prompt Elasto-Gravity Signals

Operational Earthquake Early Warning (EEW) typically provides seconds to tens of secondsof lead time, derived from the first arrivals of P and S waves. Reports of hour-scaleultra-low-frequency (ULF) magnetic anomalies preceding large earthquakes remain contentious,largely due to contamination by space-weather. We propose κ–Fusion, a physicsinformeddetector that combines robustly-normalised minute-rate magnetometer anomalieswith Prompt Elasto-Gravity Signals (PEGS), under a strict space-weather mask (Dst/Kp)and optional multi-station coherence. In back-tests around the 2016 Kumamoto sequence(Japan) and the 2016 Kaik¯oura event (New Zealand), we find minute-scale magnetic anomaliesat Kakioka (KAK) leading the foreshock by ∼4.8 h and the mainshock by ∼32.8 h, andWest Melton (EYWM) anomalies ∼30 h before Kaik¯oura, consistent with quiet-hours inFinal Dst for 12–13 Nov 2016. These results indicate hour-scale potential but require Kpfiltering, multi-station replication, and PEGS integration before operational use.