한반도 황해 해역에서 발생한 2003년 3월 23일, 3월 30일 중규모 지진의 지진원 상수 Source Parameters of Two Moderate Earthquakes at the Yellow Sea Area in the Korean Peninsula on March 22 and 30, 2003원문보기
2003년 3월 23일 한반도 홍도 해역, 3월 30일 한반도 백령도 해역에서 규모 5.0 및 4.8의 중규모 지진이 잇달아 발생하였다. 파형역산법을 적용하여 두 지진의 발진기구를 분석한 결과 3월 23일 지진은 약간의 역단층 성분을 포함하는 주향이동단층의 특성을 보이며, 3월 30일 지진은 정단층 특성을 보인다. P축의 방향은 동북동-서남서 방향으로 한반도 주응력 방향에 대한 이전 연구결과와 부합한다. 파형역산에 의한 각 지진의 모멘트규모는 4.7과 4.5로 결정되었으며, 스펙트럼 분석에 의한 각 지진의 모멘트규모는 4.8과 4.6으로 결정되었다. 홍도 해역 지진은 국지적인 응력보다는 황해에 전체적으로 작용하는 판구조적 응력 분포를 반영한다. 그러나 백령도 해역 지진은 기존의 섭입대나 충돌대에 의해 발생한 연약대가 인장방향의 응력을 받아 재활되어 발생하는 것으로 추정되며, 충돌대의 한반도 연장 가능성에 대한 지진학적 관측 증거를 간접적으로 제시한다.
2003년 3월 23일 한반도 홍도 해역, 3월 30일 한반도 백령도 해역에서 규모 5.0 및 4.8의 중규모 지진이 잇달아 발생하였다. 파형역산법을 적용하여 두 지진의 발진기구를 분석한 결과 3월 23일 지진은 약간의 역단층 성분을 포함하는 주향이동단층의 특성을 보이며, 3월 30일 지진은 정단층 특성을 보인다. P축의 방향은 동북동-서남서 방향으로 한반도 주응력 방향에 대한 이전 연구결과와 부합한다. 파형역산에 의한 각 지진의 모멘트규모는 4.7과 4.5로 결정되었으며, 스펙트럼 분석에 의한 각 지진의 모멘트규모는 4.8과 4.6으로 결정되었다. 홍도 해역 지진은 국지적인 응력보다는 황해에 전체적으로 작용하는 판구조적 응력 분포를 반영한다. 그러나 백령도 해역 지진은 기존의 섭입대나 충돌대에 의해 발생한 연약대가 인장방향의 응력을 받아 재활되어 발생하는 것으로 추정되며, 충돌대의 한반도 연장 가능성에 대한 지진학적 관측 증거를 간접적으로 제시한다.
Two moderate earthquakes with local magnitude 4.9 and 5.0 at the Yellow Sea area occurred successively around Hong island on March 22, 2003 and Baengnyeong island on March 30, 2003, respectively, close to the Korean Peninsula. Focal mechanisms by the waveform inversion analysis are strike slip fault...
Two moderate earthquakes with local magnitude 4.9 and 5.0 at the Yellow Sea area occurred successively around Hong island on March 22, 2003 and Baengnyeong island on March 30, 2003, respectively, close to the Korean Peninsula. Focal mechanisms by the waveform inversion analysis are strike slip faulting with a thrust component for the March 22 event, and normal faulting for the March 30 event. The direction of P-axes of two events were ENE-WSW which were similar to previous studies on that of P-axes in and around the Korean Peninsula. Moment magnitudes determined by the waveform inversion analysis were 4.7 and 4.5, respectively, whereas those determined by spectral analysis were 4.8 and 4.6, respectively. As regards the March 22 event, regional stress by combined tectonic forces from compressions of plates colliding to the Eurasian plate, rather than mere local stress, was indicated. However, it was estimated that the March 30 event took place when the weak zone generated from the existing collision zone was reactivated when subjected to local stress in the tensile direction. This seismological observation indirectly supports the idea that the collision zone may extend to the Korean Peninsula.
Two moderate earthquakes with local magnitude 4.9 and 5.0 at the Yellow Sea area occurred successively around Hong island on March 22, 2003 and Baengnyeong island on March 30, 2003, respectively, close to the Korean Peninsula. Focal mechanisms by the waveform inversion analysis are strike slip faulting with a thrust component for the March 22 event, and normal faulting for the March 30 event. The direction of P-axes of two events were ENE-WSW which were similar to previous studies on that of P-axes in and around the Korean Peninsula. Moment magnitudes determined by the waveform inversion analysis were 4.7 and 4.5, respectively, whereas those determined by spectral analysis were 4.8 and 4.6, respectively. As regards the March 22 event, regional stress by combined tectonic forces from compressions of plates colliding to the Eurasian plate, rather than mere local stress, was indicated. However, it was estimated that the March 30 event took place when the weak zone generated from the existing collision zone was reactivated when subjected to local stress in the tensile direction. This seismological observation indirectly supports the idea that the collision zone may extend to the Korean Peninsula.
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문제 정의
I retrieved seismic data from the KMA and KIGAM webpage. This research work is supported by the projects named ‘Earthquake monitoring at nuclear power plant (NPP) sites’ and ‘Regulatory technical development for assessment of design earthquake and surface deformation of the Korean NPP sites’ of the Korea Institute of Nuclear Safety.
제안 방법
6, respectively. It is judged that an error was made by the KMA in calculating the local magnitude, given the results of the analysis of the magnitude according to the spectral analysis conducted in this study.
이론/모형
The displacement amplitude spectra can be calculated by multiplying the transfer function of the seismic source, anelastic attenuation, geometric spreading, instrumental response and site effect terms. Amplitude spectra were calculated by the composite spectrum method by Noh et al. (2003) which vectorially combines 3 components in the frequency domain. The method is expected to enhance the signal spectrum by suppressing the relatively incoherent noise spectrum.
(2004) presented source parameters and Pn velocity of both events. They obtained the fault plane solutions of them using the grid test technique. To understand the regional stress orientation and tectonics, Kim et al.
Therefore, locations of event A and B are redetermined by making use of the model suggested by Chang and Baag (2006). This model is the one dimensional crustal velocity structure model, which was obtained by analyzing broadband seismic waveforms and travel times.
참고문헌 (23)
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