Crustal velocity structure across the southern Korean Peninsula from seismic refraction survey

Cho, Hyun-Moo; Baag, Chang‐Eob; Lee, Jung Mo; Moon, Wooil M.; Jung, Heeok; Kim, Ki Young; Asudeh, I.

doi:10.1029/2005gl025145

Cited by 58 publications

(43 citation statements)

References 8 publications

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“…If the shallow crustal velocity between the source and GKP1 is relatively lower than average crustal velocity of area A, the synthetic waveform from that can precede the observed one. This result is compatible with that of Cho et al (2006). They showed that the shallow crustal velocity of Gyeongsang basin is comparatively low.…”

Section: Discussionsupporting

confidence: 88%

Local crustal structures of southern Korea from joint analysis of waveforms and travel times

Lee

Baag

2008

Geosci J

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A joint inversion technique of waveforms and travel times is applied to broadband seismic data from a local earthquake in order to estimate local crustal velocity structures of southern Korea. Combining the waveform and travel time inversion techniques, we can surmount the demerits of the techniques: the distortion of deep velocity structure in the waveform inversion caused by low signal-to-noise ratio (SNR), the velocity-depth trade-off, and errors in picking phases in the travel time inversion. The purpose of this study is not only for verifying whether the technique is performed well in the local areas where the number of stations is limited, but also for estimating the velocity structures of the areas that have been little investigated. We adopted the genetic algorithm (GA) as a search algorithm, since we could not expect appropriate initial models due to little a priori information about crustal velocity structure. Both broadband waveforms bandpassed between 0.05 Hz and 0.3 Hz and travel times of Pg, Pn, and PmP waves from the 26 April 2004 Daegu earthquake (M L =3.9) were used as input data. We performed the joint inversion ten times or more for each local area, and adopted the averaged model of optimal models to acquire credible crustal structure. Synthetic waveforms and travel time curves obtained from the estimated velocity models were generally agreed with observed seismograms, and the estimated source depths from the velocity models of the three local areas are similar to and consistent with each other. Therefore, we believe that the joint inversion technique is still applicable to local areas where the number of stations is limited.

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Section: Discussionsupporting

confidence: 88%

Local crustal structures of southern Korea from joint analysis of waveforms and travel times

Lee

Baag

2008

Geosci J

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“…The Moho discontinuity beneath station TJN appears at a depth of 32 km. This result is similar to the other independent works (e.g., Chang and Baag, 2005;Cho et al, 2006) in which the Moho beneath station TJN appears at 33.58 km and 32.09 km, respectively. The P-wave velocity in the upper mantle is 7.67−8.02 km/s.…”

Section: Discussionsupporting

confidence: 92%

“…The low velocity layers around a depth of 10 km are not seriously interpreted at present because they are not always distinctive and because the detailed geological structure of the Okcheon Fold Belt is expected to be very complicated by locality. The midcrustal velocity discontinuity appeared strongly at a depth of around 15 km in the WNW half portion of the KCRT2002 velocity crosssection (Cho et al, 2006). Velocity jumps at a depth of 18 km are found beneath stations NPR and TJN although the former is distinctive.…”

Section: Discussionmentioning

confidence: 91%

1D crustal velocity structure beneath broadband seismic stations in the Okcheon Fold Belt of Korea by receiver function analysis

2010

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The crustal velocity structure is one of the fundamental and important subjects for seismology. The receiver function analysis technique is applied to the data from six broadband stations (HKU, JSB, MGB, NPR, SND, and TJN) in the Okcheon Fold Belt of Korea. The genetic algorithm that is independent of the initial model is adopted as the inversion method. The surfacewave dispersion data are used as constraints in the receiver function inversion. Among these stations, the receiver function analyses on the velocity structures beneath stations JSB, MGB, and SND have not been carried out before. Since recent large teleseismic earthquake data of magnitudes larger than 6.5 are included in the analyses, the velocity structures found in the present work are expected to be more reliable than those by the previous independent works. The characteristics of crustal velocity structures in the Okcheon Fold Belt are revealed. The crustal thickness in the Okcheon Fold Belt is estimated to be 32−34 km. The Moho depths are 32, 34, 32, 32−34, 32, and 32 km beneath stations HKU, JSB, MGB, NPR, SND, and TJN, respectively. These results are similar to those found in the previous independent works. The low velocity layers around the depth of 10 km are also found. Geological interpretation or correlations are, however, skipped since they are not always distinctive. Midcrustal velocity discontinuities at the 18-km depth are found beneath stations NPR and TJN although the former is only distinctive. Those at the 22-km depth are also found beneath stations HKU and SND. The crustal velocity structures estimated in this study will be able to offer fundamental information to other geologists, and the geological and tectonic interpretation of the velocity structures is expected.

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“…AC-16에서 정량적인 깊이는 굴절파 실험 두 측선 (Cho et al, 2006;의 7개 지점에서 속도층 모델(모델 5 지점에서 두 측선이 교차)을 구축하였는데( Fig. 1(b), (c)), 7개 모델은 측 선의 수직방향, 즉 2차원적으로 확장된 모델영역( Fig.…”

Section: 해석 방법unclassified

Hypocentral Depth Determination of Gyeongju Earthquake Aftershock Sequence

Chung¹,

Iqbal²

2017

Geophysics and Geophysical Exploration

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Hypocentral depths of 103 aftershocks of the 12 September 2016 Gyeongju earthquake (ML 5.8) were inverted by epicentral relocation, using HYPO71 and HYPOINVERSE. From the comparison of seven models that reflect regional velocity structure in the southern Korean Peninsula, HYPO71 with linear weighting over the whole range showed less residuals than HYPOINVERSE for the model near the epicenter. Less uncertainties of focal depths were observed for the events with large magnitude and short range of the closest S-phase distance.

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Crustal velocity structure across the southern Korean Peninsula from seismic refraction survey

Cited by 58 publications

References 8 publications

Local crustal structures of southern Korea from joint analysis of waveforms and travel times

Local crustal structures of southern Korea from joint analysis of waveforms and travel times

1D crustal velocity structure beneath broadband seismic stations in the Okcheon Fold Belt of Korea by receiver function analysis

Hypocentral Depth Determination of Gyeongju Earthquake Aftershock Sequence

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