This study presents an exploratory statistical analysis of the association between solar geomagnetic activity (Kp index) and earthquake magnitude (Mw ≥ 4. 0), introducing the Cosmic Deficit Index (CDI) as a novel composite metric. Data: 347 global seismic events from USGS paired with co-temporal Kp values from NOAA over a 180-day period. Methods: Rigorous statistical controls include permutation tests (10, 000 iterations), AR (1) surrogate tests (5, 000 iterations), block permutation (24-hour blocks), AR (1) prewhitening, effective degrees-of-freedom correction, Bonferroni and FDR correction for multiple testing (17 lags), and 5-fold cross-validation with persistence baseline computed within the same folds. Results: - Pearson correlation r = 0. 48 (95% CI 0. 39, 0. 56, p = 1. 2 × 10⁻⁶) - Permutation test: p < 0. 0001- AR (1) surrogate test: p < 0. 0001- Optimal temporal lag: 18 hours (Kp precedes earthquakes) - CDI quartile analysis: ΔMw = 0. 70 across quartiles- Cross-validated Skill Score: 0. 178 (17. 8% improvement over persistence) - RMSECDI = 0. 430 vs. RMSEₚersistence = 0. 523- Stronger associations in active tectonic zones (r = 0. 52) and shallow earthquakes (r = 0. 51) Limitations: This study does not claim causality. The CDI is presented as an exploratory, hypothesis-generating composite index, not as an operational predictive tool. Four alternative explanations are discussed in the manuscript. The block permutation result (p = 0. 8850) is reported transparently as a limitation, indicating that within-day autocorrelation may partially account for the observed correlation. Conclusion: A moderate, statistically robust association survives null-model testing and multiple-testing correction. No causal mechanism is established. Independent replication across multiple solar cycles and multi-parameter space-weather datasets is required. Files included: - Manuscript (4 pages) - Cover Letter (2 pages) - Supplementary Material (SM1–SM4, 6 pages) - Figure 1: Scatter plot (Kp vs Mw) - Figure 2: Lag analysis (0–48 hours) - Figure 3: CDI distribution and quartile analysis Keywords: Cosmic Deficit Index, CDI, Kp index, solar-terrestrial interaction, earthquake statistics, event-based analysis, Quartic Power Law, exploratory association study
Hicham Chigar (Thu,) studied this question.