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

Abstract

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.

Crustal Deformation of South Korea After the Tohoku‐Oki Earthquake: Deformation Heterogeneity and Seismic Activity

“…(a) Principal strain rate during Stage A and crustal thickness (from Hong et al, ) in South Korea. (b) Dilation rate during Stage A.…”

“…The largest instrumental earthquake was an M L 5.8 event in southeast Korea (Gyeongju) in 2016 (Hong et al, ; Kim et al, ), although an M L 6.5 earthquake was reported in the Pyeongnam Basin of North Korea (Engdahl & Villaseñor, ). The spatial distribution of historic seismicity is generally similar to that of instrumental seismicity, with the highest densities occurring in the Pyeongnam, Taebaeksan, and middle Okcheon basins, and the central part of the Yeongnam massif, whereas the central part of the Gyeonggi massif records little seismically (Hong et al, ).…”

“…The tectonic event that had the greatest influence on the present‐day configuration of the Korean Peninsula was the Permo‐Triassic collision of the North and South China cratons, as this collision belt extended into the Imjingang Belt of Korea (Chough et al, ; Ree et al, ). The inland crustal thickness ranges from 26 to 36 km, and the Moho depth generally coincides with the surface topography (Chang & Baag, ; Hong et al, ). The crust is relatively thicker in the central and southwestern parts of the southern peninsula.…”

“…The crustal provinces of Korea described above have often been considered as seismotectonic provinces, although until recently, seismic activity and current crustal deformation were not taken into consideration when describing the tectonics of the region (Kyung & Lee, ; Lee & Jung, ; Lee & Kim, ; Rhee et al, ). Hong et al () suggested an improved model of seismotectonic provinces in South Korea based on integrated geological, geophysical, and tectonic data, with the resultant zonation of seismotectonic provinces differing from traditional models.…”

The 12 September 2016ML5.8 midcrustal earthquake in the Korean Peninsula and its seismic implications

“…Historically, there have been many large earthquakes in the Korean Peninsula [Lee and Yang, 2006;Seo et al, 2010;Houng and Hong, 2013;Hong et al, 2016;Park and Hong, 2016]. There is growing concern that large earthquakes will occur in the near future due to the influence of the 2011 Tohoku-Oki megathrust earthquake.…”