Depth-dependent seismicity and crustal heterogeneity in South Korea

Chung, Tae Woong; Iqbal, Muhammad Zafar; Lee, Young-Min; Yoshimoto, Keitaro; Jeong, Jin-A

doi:10.1016/j.tecto.2018.10.020

Cited by 10 publications

(6 citation statements)

References 47 publications

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“…Most of the faults in Figure 3 have not been clarified for their activity. Recent studies (Lee et al 2018;Woo et al 2019), based on micro-seismicity related to the 2016 M 5.8 earthquake, differentiated active faults, including the YF and UF, into the Gaum fault (GF),…”

Section: Resultsmentioning

confidence: 99%

“…Although it seems to affect the high values in the area between the M 5.8 and M 5.5 earthquakes in layers 1-3, the location of the M 5.5 event is less relevant to the faults shown in Figure 4. This earthquake, however, was discovered to not be a natural event but rather a disturbance induced by water injection into the ground at a nearby geothermal plant (Grigoli et al 2018;Kim et al 2018;Chung et al 2018).…”

Section: Resultsmentioning

confidence: 99%

“…Southeastern Korea is mainly occupied by the Gyeongsang basin, formed in the Cretaceous on top of the Yeongnam massif, which is another Precambrian massif along with the Gyeonggi massif ( Figure 1). The Yeonil basin, originated in the Miocene, exist on the eastern coast of the Gyeongsang basin (Ree et al 2003;Son et al 2013;Lee et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to these, several faults were newly included as active faults associated with the M 5.8 earthquake (Lee et al 2018(Lee et al , 2019. Several cultural heritage sites, including the capital of the longest dynasty in ancient Korea, as well as many industrial facilities, including nuclear power plants, are located in the vicinity of these faults.…”

Section: Introductionmentioning

confidence: 99%

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Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Iqbal

Chung

Nam

2020

Preprint

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Two recent hazardous earthquakes ( M 5.8 and 5.5) in southeastern Korea were the largest instrumentally recorded inland events after an abnormally long, seismically quiet, period. In this study, we used coda envelope tomography to observe the heterogeneities related to active faults, which can, in turn, help mitigate seismic hazard in the area. However, this tomography was not able to detect faults in the intraplate region. By separating the periods before and after the M 5.8 earthquake, we analyzed 225 and 204 seismograms obtained from 127 and 86 events, respectively. Both periods showed time-varying heterogeneity correlated with fault activity. Adding 446 seismograms from 235 aftershocks of the two events to the analysis showed us a heterogenous structure that closely correlated to the active faults where the recent earthquakes originated.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Iqbal

Chung

Nam

2020

Preprint

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“…Also, Westaway and Burnside [41] named the new fault as the Namsong fault on the basis of the aftershock distribution of the Pohang earthquake ( Figure 1) and proposed that the fault has been already critically stressed before the EGS project [41]. In addition, according to the Korea Meteorological Administration (KMA), the depths of the 2017 Pohang earthquake and aftershocks are less than 16 km, which is shallower than the Moho depth (~28 km) of the region [42]. Kennedy and Van Soest [37] suggested that the mantle fluids of the San Andreas Fault penetrate the brittle-ductile boundary based on helium isotope ratios and strain rates measured by GPS.…”

Section: Helium Isotope Geochemistry In the Pohangmentioning

confidence: 99%

Mantle-Derived Helium Emission near the Pohang EGS Site, South Korea: Implications for Active Fault Distribution

Kim

Lee

et al. 2020

Geofluids

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An Mw 5.5 earthquake occurred in Pohang, South Korea on November 15, 2017, resulting in a great impact on society. Despite a lot of controversy about the cause of the earthquake in relation to the enhanced geothermal system (EGS), the location of earthquake-related active faults is poorly known. Here, we first report the results of the geochemical and isotopic analyses of dissolved gases in groundwater in the Heunghae, Yeonil, and Sinkwang areas. According to the N2-Ar-He relationship, samples from the Heunghae and Yeonil areas are contributed to the mantle, except for the Sinkwang area, where all samples are atmospheric. The Pohang samples consist mainly of N2 and CO2, and some samples of the Heunghae and Yeonil areas contain substantial CH4. Stable isotope compositions of N2 (δ15N=0.2 to 3.6‰), CO2 (δ13C=−27.3 to−16.0‰), and CH4 (δ13C=−76.1 to−70.0‰) indicate that these components are derived from organic substances in sedimentary layer of Pohang Basin. On the other hand, helium isotope ratios (3He/4He, up to 3.83 Ra) represent the significant mantle contribution in the Heunghae and Yeonil areas. Through the distribution of high 3He/4He ratios, we propose that the Heunghae, Namsong, and Jamyeong faults are the passage of mantle-derived fluids. Computed 3He fluxes of the Heunghae (120 to 3,000 atoms cm-2 sec-1), Namsong (52 to 1,300 atoms cm-2 sec-1), and Jamyeong (83 to 2,100 atoms cm-2 sec-1) faults are comparable to other major active faults around the world, reflecting either high porosity or high helium flow rates. Therefore, our results demonstrate that there are active faults near the EGS facilities, which can provide the basis for future studies.

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Coda-Wave Based Monitoring of Pore-Pressure Depletion-driven Compaction of Slochteren Sandstone Samples from the Groningen Gas Field

Zotz-wilson¹,

Filippidou²,

Linden³

et al. 2020

Preprint

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Depth-dependent seismicity and crustal heterogeneity in South Korea

Cited by 10 publications

References 47 publications

Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Mantle-Derived Helium Emission near the Pohang EGS Site, South Korea: Implications for Active Fault Distribution

Coda-Wave Based Monitoring of Pore-Pressure Depletion-driven Compaction of Slochteren Sandstone Samples from the Groningen Gas Field

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