Neotectonic Crustal Deformation and Current Stress Field in the Korean Peninsula and Their Tectonic Implications: A Review

Abstract

In order to characterize the Neotectonic crustal deformation and current stress field in and around the Korean Peninsula and to interpret their tectonic implications, this paper synthetically analyzes the previous Quaternary fault and focal mechanism solution data and recent geotechnical in-situ stress data and examines the characteristics of crustal deformations and tectonic settings in and around East Asia after the Miocene. Most of the Quaternary fault outcrops in SE Korea occur along major inherited fault zones and show a NS-striking top-to-the-west thrust geometry, indicating that the faults were produced by local reactivation of appropriately oriented preexisting weaknesses under EW-trending pure compressional stress field. The focal mechanism solutions in and around the Korean Peninsula disclose that strike-slip faulting containing some reverse-slip component and reverse-slip faulting are significantly dominant on land and in sea area, respectively. The P-axes are horizontally clustered in ENE-WSW direction, whereas the T-axes are girdle-distributed in NNW direction. The geotechnical in-situ stress data in South Korea also indicate

Stratigraphic Constraints of Rupture Kinematics and Scenarios of Paleoearthquakes on the Southern Yangsan Fault, SE Korea

“…The stress state of the peninsula is dependent on the interaction between the subducting Pacific and Philippine Sea plate, as well as collision of the northward-moving Indian plate with the Eurasian plate (Yin, 2010). Various investigations of the present tectonic stress, including those involving hydrofracturing/overcoring (e.g., Haimson et al, 2003;Bae et al, 2008;Chang et al, 2010), focal mechanisms (e.g., Park et al, 2007;Hoe & Kyung, 2008;Back et al, 2011;Choi, H. et al, 2012), and fault slip (e.g., Kim et al, 2016) analyses, indicate an ENE-WSW-trending maximum horizontal stress axis.…”

“…Several paleoseismic studies along the YF have been conducted since the 1990s (e.g., Okada et al 1994;Choi, S.-J. et al, 2012;Lee et al, 2015;Kim et al, 2016;Cheon et al, 2020;Song et al, 2020). However, it is difficult to identify field evidence for paleoseismicity owing to intense modification of the geomorphic expression of ruptures by surface processes (mostly erosion and deposition) and urbanization.…”

Near-surface termination of upward-propagating strike-slip ruptures on the Yangsan Fault, Korea

“…1 ) and the far-field stress transmitted by the northward moving Indian plate. The neotectoic setting of the peninsula is known to have been initiated at 5–3.5 Ma (early Pliocene) 29 , 30 . Comprehensive data obtained from earthquake focal mechanisms, in situ stress measurements (hydrofracturing/overcoring methods), and Quaternary fault slips in the onshore area of the peninsula reveal an ENE–WSW-oriented maximum horizontal stress (σ Hmax ) 30 .…”

“…The neotectoic setting of the peninsula is known to have been initiated at 5–3.5 Ma (early Pliocene) 29 , 30 . Comprehensive data obtained from earthquake focal mechanisms, in situ stress measurements (hydrofracturing/overcoring methods), and Quaternary fault slips in the onshore area of the peninsula reveal an ENE–WSW-oriented maximum horizontal stress (σ Hmax ) 30 . Significantly, the general stress field is regarded as a strike-slip regime (σ 2 is vertical), as inferred from focal mechanism data 31 – 33 .…”