Surface Deformations and Rupture Processes Associated with the 2017 Mw 5.4 Pohang, Korea, Earthquake

Choi, Jin‐Hyuck; Ko, Kyoungtae; Gihm, Yong Sik; Cho, Chang Soo; Lee, Hoonyol; Song, Seok Goo; Bang, Eun‐Seok; Lee, Hong‐Jin; Bae, Hankyung; Kim, Sung Won; Choi, Sung‐Ja; Lee, Sung-Soon; Lee, Seung Ryeol

doi:10.1785/0120180167

Cited by 39 publications

(51 citation statements)

References 22 publications

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“…The distribution of Quaternary faults and mechanisms involved are consistent with the maximum principal stress direction (E-W; ENE-WSW) during the Quaternary period [54][55][56]. The recorded seismic data along this area suggest that this area has experienced four moderate magnitude earthquakes (Mw 5-6) during the last 14 years, including the 2016 Gyeongju earthquake (Mw 5.5) and the 2017 Pohang earthquake (Mw 5.4) [47][48][49]. Figure 1.…”

Section: Geological Settingssupporting

confidence: 53%

“…The southern part of the Korean Peninsula is located on the Eurasian Plate and its tectonic activities are controlled by the ongoing subduction of the adjoining Pacific and Philippine Sea Plates. Moreover, the collision between the Indian Plate with Eurasian Plate controls the tectonism of the Korean Peninsula [47][48][49][50][51]. The Cenozoic deformation along the southeastern part of the Korean Peninsula is accommodated by the Yangsan-Ulsan Fault system.…”

Section: Geological Settingsmentioning

confidence: 99%

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Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

et al. 2020

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Studies on earthquake-induced liquefaction and identification of source unit for causing liquefaction have been a major concern in sustainable land use development especially in low to moderate seismic areas. During the 2017 M w 5.4 Pohang earthquake, widespread liquefaction was reported around the Heunghae basin, which was the first ever reported case of liquefaction in the modern seismic history of Korea. The epicentral area is one of the major industrial hubs along the SE Korean Peninsula with no detailed liquefaction hazard map. The purpose of this study was to determine the land damage classification on the basis of surface manifestation of liquefaction features and carry out detailed liquefaction potential analysis to delineate the depth of liquefiable soil. This will eventually support developing a liquefaction hazard zonation map and sustainable development of infrastructure to minimize earthquake damages. In this present study, the southern part of the Heunghae basin, which has more field evidences of liquefaction than the northern part, was taken for detailed liquefaction analysis. From the detailed analysis, it was observed that the soils from 1.5 to 15 m depth with the probability of liquefaction varying from 2 to 20 are prone to liquefaction. On the basis of land damage pattern, the epicentral area falls in orange to red zone, which means the necessity of further detailed liquefaction analysis. This study urges more detailed liquefaction zonation should be carried out for the epicentral area and liquefaction hazard should be included in the multi-hazard map in the future for the sustainable land use planning.

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Section: Geological Settingssupporting

confidence: 53%

Section: Geological Settingsmentioning

confidence: 99%

Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

et al. 2020

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“…Although no primary surface rupture was reported during the Pohang earthquake [36], numerous liquefactions and related phenomena were witnessed by local people such as differential settlement of buildings and lateral spreading [36]. Because the liquefaction phenomenon occurred during this earthquake is the first reporting since 1978, it can provide useful information of liquefaction associated with paleo-earthquakes and future earthquakes in the areas of similar geological settings around the Korean Peninsula.…”

Section: General Characteristics Of the Pohang Earthquake On 15th Novmentioning

confidence: 92%

“…Recent paleoseismic studies suggested Pohang basin is having seismic threats from the Yangsan fault which one of the prominent dextral strike slip fault around the study area [36] (Figure 2). A recent study reported Paleo-liquefaction features in epicenter area of the Pohang earthquake [40], which indicates that the area has undergone repeated liquefactions.…”

Section: Geological Geomorphological and Tectonic Setting Of The Areamentioning

confidence: 99%

“…Major striking features associated with the Pohang earthquake were the occurrence of severe liquefaction, structural damages including residential and academic buildings, as well as lateral spreading/ground cracks. Because this is the first earthquake related liquefaction in the modern seismic history of Korea, the field survey and mechanism involved will help to guide us for the future liquefaction hazard analysis and assessment [36]. For the detailed documentation of ground deformation features (sand boils, cracks, damaged buildings, etc.…”

Section: Mapping Of Liquefaction and Related Featuresmentioning

confidence: 99%

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Geological and Structural Control on Localized Ground Effects within the Heunghae Basin during the Pohang Earthquake (MW 5.4, 15th November 2017), South Korea

Naik

Kim

et al. 2019

Geosciences

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On 15th November 2017, the Pohang earthquake (Mw 5.4) had strong ground shaking that caused severe liquefaction and lateral spreading across the Heunghae Basin, around Pohang city, South Korea. Such liquefaction is a rare phenomenon during small or moderate earthquakes (MW < 5.5). There are only a few examples around the globe, but more so in the Korean Peninsula. In this paper, we present the results of a systematic survey of the secondary ground effects—i.e., soil liquefaction and ground cracks—developed during the earthquake. Most of the liquefaction sites are clustered near the epicenter and close to the Heunghae fault. Based on the geology, tectonic setting, distribution, and clustering of the sand boils along the southern part of the Heunghae Basin, we propose a geological model, suggesting that the Heunghae fault may have acted as a barrier to the propagation of seismic waves. Other factors like the mountain basin effect and/or amplification of seismic waves by a blind thrust fault could play an important role. Liquefaction phenomenon associated with the 2017 Pohang earthquake emphasizes that there is an urgent need of liquefaction potential mapping for the Pohang city and other areas with a similar geological setting. In areas underlain by extensive unconsolidated basin fill sediments—where the records of past earthquakes are exiguous or indistinct and there is poor implementation of building codes—future earthquakes of similar or larger magnitude as the Pohang earthquake are likely to occur again. Therefore, this represents a hazard that may cause significant societal and economic threats in the future.

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Ground vulnerability derived from the horizontal‐to‐vertical spectral ratio: Comparison with the damage distribution caused by the 2017 M_L 5.4 Pohang earthquake, Korea

Kang

Kim

Choi

et al. 2021

Near Surface Geophysics

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The city of Pohang in South Korea experienced substantial damage following the M L 5.4 earthquake on 15 November 2017. Damage surveys immediately after the earthquake revealed significant spatial variations in damage intensity across the epicentral area. We collected ambient noise data (three-component seismic data) from 124 locations in Pohang, covering a total area of 17 km × 20 km, and applied the horizontalto-vertical spectral ratio technique to estimate the resonance frequency, amplification factor and vulnerability of the ground to seismic shaking. Spatial variations exhibited by these three parameters are strongly correlated and consistent with variations in local geology. By comparing the distribution of the ground vulnerability index (Kg) with the damage distribution (or intensity) documented by the Korea Meteorological Administration following the earthquake, we confirm that the site effect is the prevailing effect that influences damage intensity in this region. We also demonstrate that Kg is an efficient proxy for identifying relatively fragile zones during ground shaking: in areas with a reported damage intensity of VIII, the proportion of the area with Kg > 20 is as high as 78.2%. Given that the study area has experienced a recent moderate earthquake, with significant economic consequences, our new results and analytical techniques will provide valuable information for future urbanization projects.

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Surface Deformations and Rupture Processes Associated with the 2017 Mw 5.4 Pohang, Korea, Earthquake

Cited by 39 publications

References 22 publications

Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

Geological and Structural Control on Localized Ground Effects within the Heunghae Basin during the Pohang Earthquake (MW 5.4, 15th November 2017), South Korea

Ground vulnerability derived from the horizontal‐to‐vertical spectral ratio: Comparison with the damage distribution caused by the 2017 M_L 5.4 Pohang earthquake, Korea

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Surface Deformations and Rupture Processes Associated with the 2017 Mw 5.4 Pohang, Korea, Earthquake

Cited by 39 publications

References 22 publications

Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

Land Damage Mapping and Liquefaction Potential Analysis of Soils from the Epicentral Region of 2017 Pohang Mw 5.4 Earthquake, South Korea

Geological and Structural Control on Localized Ground Effects within the Heunghae Basin during the Pohang Earthquake (MW 5.4, 15th November 2017), South Korea

Ground vulnerability derived from the horizontal‐to‐vertical spectral ratio: Comparison with the damage distribution caused by the 2017 ML 5.4 Pohang earthquake, Korea

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Ground vulnerability derived from the horizontal‐to‐vertical spectral ratio: Comparison with the damage distribution caused by the 2017 M_L 5.4 Pohang earthquake, Korea