Seismotectonic Properties and Zonation of the Far-Eastern Eurasian Plate Around the Korean Peninsula

Regional seismotectonics provides crucial information for seismic hazard analysis, which is difficult to address with short-term earthquake records. The far-eastern Eurasian plate around the Korean Peninsula presents a stable intraplate environment with diffuse seismicity, of which responsible tectonics and active faults are difficult to identify. Combined analysis of instrumental and historical earthquake records is required for assessment of long-term seismicity properties. Seismotectonic provinces are identified from the spatial distribution of seismicity properties controlled by the medium properties and stress field. The boundaries of the seismotectonic provinces are defined considering the medium properties that can be inferred from geological, geophysical and tectonic features. The Gutenberg–Richter frequency–magnitude relationships and maximum magnitudes for the seismotectonic provinces are determined using instrumental and historical earthquake records. The validity of maximum magnitude estimation is tested with synthetic data. A parametric method, the Tate–Pisarenko method, produces more accurate estimates than non-parametric methods. A modified Tate–Pisarenko method is proposed for estimation of maximum magnitudes for incomplete short-term earthquake catalogs. The maximum magnitude of events for the whole region is approximately the same as the average of the maximum magnitudes of events for subdivided provinces, causing apparent variation in maximum magnitudes depending on the number of seismotectonic provinces. Consideration of a reasonable number of seismotectonic provinces may be needed for proper assessment of seismic hazard potentials is recommended. The combined analysis of historical and instrumental earthquake records suggests maximum magnitudes greater than 7 around the peninsula.