• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.191-202
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• 2007

To identify the detailed attenuation structure in the southern Korean Peninsula, a numerical test was conducted for the Q tomography inversion to be applied to the accumulated dataset until 2005. In particular, the stochastic pointsource ground-motion model (STGM model; Boore, 2003) was adopted for the 2D Q tomography inversion for direct application to simulating the strong ground-motion. Simultaneous inversion of the STGM model parameters with a regional single Q model was performed to evaluate the source and site effects which were necessary to generate an artificial dataset for the numerical test. The artificial dataset consists of simulated Fourier spectra that resemble the real data in the magnitude-distance-frequency-error distribution except replacement of the regional single Q model with a checkerboard type of high and low values of laterally varying Q models. The total number of Q blocks used for the checkerboard test was 75 (grid size of $35{\times}44km^2$ for Q blocks); Q functional form of $Q_0f^{\eta}$ ($Q_0$=100 or 500, 0.0 < ${\eta}$ < 1.0) was assigned to each Q block for the checkerboard test. The checkerboard test has been implemented in three steps. At the first step, the initial values of Q-values for 75 blocks were estimated. At the second step, the site amplification function was estimated by using the initial guess of A(f) which is the mean site amplification functions (Yun and Suh, 2007) for the site class. The last step is to invert the tomographic Q-values of 75 blocks based on the results of the first and second steps. As a result of the checkerboard test, it was demonstrated that Q-values could be robustly estimated by using the 2D Q tomography inversion method even in the presence of perturbed source and site effects from the true input model.

• The Korean Journal of Petroleum Geology
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• v.3 no.1 s.4
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• pp.1-15
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• 1995

Seismic reflection profiles and exploratory drilling well samples from the southern marginal-continental shelf basin of Korea delineate that the Tertiary sedimentary sequences can be grouped into five sequences (Sequence A, Sequence B, Sequence C, Sequence D and Sequence E, in descending order). Paleontologic data, K-Ar age datings, correlation with tuff layers and sequence stratigraphic analysis reveal that the sequences A, B, C, D and E can be considered as the deposits of Holocene $\~$ Pleistocene, Pliocene, Late Miocene, Early $\~$ Middle Miocene and Oligocene, respectively. The sequence stratigraphic and structural analyses suggest that the southern part of the Cheju Basin had experienced severe folding and faulting. NE-SW trending strike-slip movement is responsible for the deformation. The sinistral movement of strike-slip fault ceased before the deposition of Sequence B. Age dating and rare-earth elements analysis of volvanic rocks reveal+ that the Sequence D was deposited during the Early $\~$ Middle Miocene and the Sequence I was deposited earlier than the deposition of the Green Tuff Formation. Sedimentary petrological studies indicate that sediments of the Sequence I came from the continental block provenance. After the deposition of the Sequence E, uplift of the source area resulted in increase of sediment supply, subsidence and volcanic activities. The Sequence D show these factors and the sediments of the Sequence D are considered to be transported from the recycled orogenic belt.