Fault intersections control short period intraplate start-stop seismicity in the Korean Peninsula

Malehmir, Alireza; Hong, Tae‐Kyung; Lee, Junhyung; Zappalá, Samuel; Brodic, Bojan; Chung, Dong-Yong; Kim, Byeong-Woo; Park, Seongjun; Lee, Jeongin; Kil, Dongwoo

doi:10.1016/j.tecto.2022.229387

Cited by 9 publications

(21 citation statements)

References 21 publications

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“…This dip angle was to a certain degree speculated upon by Malehmir et al. (2022) for Pocheon fault but is different from previous suggestions (Hong et al., 2021). Surface projection of these reflections corresponds to the location of strong surface‐wave back scattered energy at the mapped position of the Pocheon fault.…”

Section: Discussioncontrasting

confidence: 99%

“…Tests were carried out at receiver location 10 (easternmost part of the profile) with 40 landstreamer recorders deployed for this purpose. Given the earlier successful study of a similar setup (Malehmir et al., 2022), the intention was primarily to check if the two sources were phase‐locked and synchronized. Different linear upsweeps with frequency ranges 5–120, 5–140, 10–120, and 10–140 Hz, with varying lengths of 16 and 18 s were tested.…”

Section: Seismic Data Acquisitionmentioning

confidence: 99%

“…Landstreamer and wireless data were processed separately and merged after stack using a similar procedure as described by Malehmir et al. (2022). Landstreamer data were handled with a straightforward processing scheme with the aim of imaging the top of the bedrock.…”

Section: Seismic Data Analysismentioning

confidence: 99%

“…P1 was located on the northern side of metropolitan Seoul while P2 was positioned in the central part of the city where the Chugaryeong fault intersects a cluster of seismicity. Given the encouraging results from the 2020 survey, especially along P1 where reflections down to 8–9 km depth were imaged and showed both spatial and temporal correlation with the clustered seismicity (Malehmir et al., 2022), a new survey was justified to shed light on the overall subsurface geometry of the three major fault systems. In July 2021, a new seismic profile (P3), approximately 40 km, was acquired (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“… (a) Recent seismicity recorded in South Korea and the location of the seismic profile (P3, acquired in July 2021) in relation to the previous ones (P1 and P2) acquired in November 2020 (Malehmir et al., 2022). Profile P3 crosses the three major fault systems with the aim to reconstruct their geometries at depth.…”

Section: Introductionmentioning

confidence: 99%

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Crustal‐Scale Fault Systems in the Korean Peninsula Unraveled by Reflection Seismic Data

Zappalá

Malehmir

Hong

et al. 2022

Earth and Space Science

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An approximately 40‐km long high‐resolution reflection seismic profile (P3) was acquired in the metropolitan area of Seoul in South Korea for the purpose of fault system imaging in a highly noisy and challenging urban environment. Two 12t seismic vibrators (mini‐vibs) were used as the seismic source. Data were recorded using a dual element seismic spread; 20 m spaced 421 wireless seismic recorders connected to 10 Hz geophones and 20 micro‐electro‐mechanical‐based landstreamer sensors (2 m sensor spacing) attached to one of the vibrators. The purpose of the dual spread employed was to delineate both near‐surface and deep structures. The processing results show good quality and the processing work was complemented by different analysis to further constraints the geological interpretation. The survey results provide evidence for the 3D geometry of three fault systems, including Chugaryeong, Pocheon, and Wangsukcheon faults. A gently westerly dipping set of reflectivity underlying a dome‐shaped package of reflectivity is interpreted as a fault, and could project to the known surface position of the Pocheon fault. The dome‐shaped reflectivity is interpreted as folded and faulted dyke or sill systems. Downward continuation of the interpreted fault intersects the sub‐vertical Chugaryeong fault in a zone where the current seismicity is observed, suggesting that these two major fault systems may have jointly evolved in the form of splay faults. Reflections from the Wangsukcheon fault are also present in the data and interpreted to dip approximately 60° to the east, in an opposite direction to the two other faults.

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Section: Discussioncontrasting

confidence: 99%

Section: Seismic Data Acquisitionmentioning

confidence: 99%

Section: Seismic Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crustal‐Scale Fault Systems in the Korean Peninsula Unraveled by Reflection Seismic Data

Zappalá

Malehmir

Hong

et al. 2022

Earth and Space Science

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Crustal-scale fault systems in the Korean Peninsula unraveled by reflection seismic data

Zappalá

Malehmir

Hong

et al. 2022

Preprint

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Role of Backbone Fault System on Earthquake Spawning and Geohazards in the Seoul Metropolitan Area

Park

Hong

Kim

et al. 2023

Earth and Space Science

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Major earthquakes in continental regions may cause significant damage. Preexisting fault system across megacity receives high attention for possible seismic damages. Earthquake occurrence mechanism is important to assess the geohazard potentials. Continental‐scale Quaternary fault system is developed across the Seoul metropolitan area where the population is the largest in the Korean Peninsula. Historical seismic‐damage records suggest potential seismic hazards in the Seoul metropolitan area. We investigate the fault motions and spatial distribution of earthquakes in the Seoul metropolitan area using a matched‐filter technique that is based on stacked waveform crosscorrelation functions among densely‐deployed seismic stations. The analysis detects 1103 earthquakes that include 360 events with magnitudes (ML) of −0.6 to 2.0 around the Chugaryeong fault and 34 events with magnitudes of −0.5 to 2.7 around Wangsukcheon, Pocheon, and Yeseonggang faults. The seismicity suggests a set of near‐vertical subparallel (or orthogonal) faults that develop from the major faults. A major fault system behaves as a backbone structure that makes branch faults develop, producing seismicity including major earthquakes. The backbone structure may control the fault development that conforms to the ambient stress field. The backbone faults may play a role to increase geohazard potentials.

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Fault intersections control short period intraplate start-stop seismicity in the Korean Peninsula

Cited by 9 publications

References 21 publications

Crustal‐Scale Fault Systems in the Korean Peninsula Unraveled by Reflection Seismic Data

Crustal‐Scale Fault Systems in the Korean Peninsula Unraveled by Reflection Seismic Data

Crustal-scale fault systems in the Korean Peninsula unraveled by reflection seismic data

Role of Backbone Fault System on Earthquake Spawning and Geohazards in the Seoul Metropolitan Area

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