TITLE:
Geostatistical Analysis for Magnitude Scale Conversion and Gutenberg-Richter Parameter Estimation: Insights from Regional Seismicity of Nubian-Eurasian Plate Boundary Region
AUTHORS:
Peter Adetokunbo, Ayodeji Adekunle Eluyemi, Eniolayimika Jegede, Segun Aguda, Tunji Omoseyin, Debasis D. Mohanty, Manzunzu Brassnavy, Paulina Amponsah, Saurabh Baruah
KEYWORDS:
Magnitude Conversion, Gutenberg-Richter Parameters, Machine Learning, Seismic Hazard, b-Value, Magnitude of Completeness, Nubian-Eurasian Plate Boundary
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.7,
July
24,
2025
ABSTRACT: This work presents the analyses of earthquake magnitude scales and seismicity parameters across the Nubian-Eurasian Plate Boundary Region. We developed magnitude conversion models using three regression techniques (R2 ≈ 0.68) and implemented a tapered Gutenberg-Richter model with bootstrap uncertainty quantification. Our analysis yielded Mc = 4.35, b-value = 0.93 (95% CI: 0.74 - 1.09), a-value = 6.19 (95% CI: 5.35 - 6.90), corner magnitude = 8.69 (95% CI: 5.77 - 8.69), and maximum magnitude (Mmax) = 7.24 (95% CI: 6.50 - 7.24). The tapered model provides superior fitting at higher magnitudes compared to the standard Gutenberg-Richter relationship, addressing a key limitation in seismic hazard characterization. The b-value below 1.0 indicates elevated potential for higher-magnitude events, while the substantial a-value suggests significant seismic productivity across the boundary. The relatively high Mc value points to limitations in detecting smaller earthquakes, particularly in less-instrumented areas of the boundary zone. The estimated Mmax and corner magnitude constrain the upper bound of potential earthquake magnitudes, critical for hazard assessments and engineering applications. While treating the region as a single seismotectonic unit was necessary given current data constraints, we acknowledge this approach’s limitations given the boundary’s diverse tectonic regimes. Future research should develop zone-specific parameters that account for distinct regional characteristics. Nevertheless, these region-wide parameters establish a valuable baseline framework for seismic hazard assessment, particularly useful where zone-specific data remain insufficient.