Stable isotope profiles of Serripes groenlandicus shells.I. Seasonal and interannual variations of Alaskan Coastal Water in the Bering and Chukchi Seas

Boo-Keun,Khim 한국지질과학협의회 2002 Geosciences Journal Vol.6 No.4

Serripes groenlandicus shells were collected alivefrom the eastern regions of the Bering and Chukchi seas whereAlaskan Coastal Water occupies dominantly. High-resolution sta-ble isotope profiles of the shell carbonates exhibit distinct, appar-ently annual, cycles caused by seasonal variations of temperature,seawater isotopic composition and other factors. The shell d18Oprofiles show a moderately high-amplitude seasonal temperaturecycle with considerable interannual variability. Superimposed onthe temperature-controlled cycles are periodic excursions whichare associated with reduced salinity, and more negative seawaterd18O, related presumably to an increased freshwater flux to theAlaskan Coastal Current during the summer. Comparison betweentwo oxygen isotope profiles supports the occurrence of seasonaland interannual variability of Alaskan Coastal Water in the east-ern part of the Bering and Chukchi Shelf. The cycles in the d13Cprofiles are interpreted as being controlled primarily by phy-toplankton productivity and seasonal temperature. In addition, atrend of more negative d13C values towards the later stage ofgrowth may reflect physiological changes associated with sexualmaturity, gametogenesis, and slower growth rate. The oxygen andcarbon isotope profiles as a biorecorder of bivalve shells are sub-stantiated in the subarctic environments, probing the seasonal andinterannual variation of Alaskan Coastal Water.

Hydraulic conductivity and mechanical stiffness tensors for variably saturated true anisotropic intact rock matrices, joints, joint sets, and jointed rock masses

Jun-Mo,Kim 한국지질과학협의회 2007 Geosciences Journal Vol.11 No.4

: A series of global hydraulic conductivity and mechanical stiffness tensors for variably saturated true anisotropic intact rock matrices, joints, joint sets, and jointed rock masses is formulated to expand the fully coupled poroelastic governing equations presented by Kim (2004) for groundwater flow and solid skeleton deformation in porous geologic media to those for fractured and fractured porous geologic media. The global hydraulic conductivity tensors are derived from the local hydraulic conductivity tensors using coordinate transformation on the basis of the generalized Darcys law. The global mechanical stiffness tensors are then derived from the local or global mechanical compliance tensors using coordinate transformation on the basis of the generalized Hookes law.

Geological age of the Jeongseon Formation, Joseon Supergroup (lower Paleozoic): A perspective from carbon isotope stratigraphy

홍성경,Yong,Il,Lee 한국지질과학협의회 2007 Geosciences Journal Vol.11 No.1

Due to the lack of index fossils and extensive alter-ation, the geological age of the Jeongseon Formation, JeongseonUnit of the Joseon Supergroup (lower Paleozoic) is yet clearlydefined by any chronostratigraphic mean. In this study, we presentJeongseon Formation. The carbon isotopic values of the JeongseonFormation fluctuate between -3‰ and +1‰, which are within therange of those of Middle Ordovician carbonate. Also, the δ13Ccurve of the upper part of the Jeongseon Formation is well cor-related with that of the uppermost Midle-lowermost UpperOrdovician Copenhagen Formation in the Great Basin, U.S.A.(Saltzman and Young, 2005). Considering general biostratigraphyand carbon isotope stratigraphy together, the age of the upperpart of the Jeongseon Formation can be assigned to late Middle to

The 20 January 2007, Mw 4.48, Odaesan, Korea, earthquake

Namdae,Jo,Chang-Eob,Baag 한국지질과학협의회 2007 Geosciences Journal Vol.11 No.1

Jo, N.-D. and Baag, C.-E., 203, Estimation of spectrum decayparameter κ and stochastic prediction of strong ground motionsin southeastern Korea. Journal of the Earthquake EngineeringSociety of Korea, 7, 5970. (in Korean with English abstract)Junn, J.-G., Jo, N.-D. and Baag, C.-E., 2002, Stochastic prediction ofground motions in southern Korea. Geosciences Journal, 5, 1726.Kang, T.-S. and Baag, C.-E., 2004, The 29 May 2004, Mw=5.1, off-shore Uljin earthquake, Korea. Geosciences Journal, 8, 115123.KIGAM, 2007, http://quake.kigam.re.kr.Kim, W., Kim, S. K. and Baag, C.-E., 206, Optimum design foraccelerograph network and instrumental intensity in South Korea.Technical Report to Korea Meteorological Administration, Pre-pared by Earthquake Engineering Society of Korea, 107 p. (in Korean)Kim, W., 2007, Earthquakes in Stable Continental Region, 1-dayworkshop for seismic observation and analysis Earthquakes in

Deep geoelectrical structure in and around the southern Korean Peninsula by GDS study

Seokhoon,Oh,Jun-Mo,Yang,Duk,Kee,Lee,Byung-Doo,Kwon,Seung-Hwan,Chung,Yoonho,Song,Kyung,Duck,Min,Masao,Nakada,Toru,Mogi,Heuisoon,Lee 한국지질과학협의회 2006 Geosciences Journal Vol.10 No.4

Estimation of site-dependent spectral decay parameter from earthquake ground motions in southern Korea

Namdae,Jo,Chang-Eob,Baag 한국지질과학협의회 2007 Geosciences Journal Vol.11 No.2

For the simulation of ground motions, various seismic parameters are to be estimated in the region where the motions are applicable. One of the most important parameters is the spectral decay parameter . The spectral decay parameter  in conventional sense is for a regional area rather than for a local site. For the site-specific simulation of ground motions, however, a site-dependent spectral decay parameter should be estimated at an observation site. It is difficult to deduce the characteristics of each observation site using the conventional procedure. In order to obtain the site-dependent spectral decay parameter , we should estimate site-independent q and site-specific s successively. A procedure is to use the coda normalization method for the computation of q value as the first step followed by the next step, the computation of s for each site using the given q evaluated at the first step. For the application of the method, we used a total of 754 accelerograms from small earthquakes occurring in southern Korea from January 1999 to April 2003. After inversion process for q, we obtained the q value of 0.0001382 sec/km in southern Korea. The s values are distributed from -0.15 to 0.35 second at 29 observation sites. The values of s are relatively large at the eastern and southern part of southern Korea. In addition, we also estimated the value of 0, distance independent term of  at regional area, as 0.007 second using all acceleration spectra in southern Korea.

Q-values for P and S waves in the southern Korean Peninsula based on the coda-normalization method

Sung,Kyun,Kim,Jae,Yol,Yang,Jinyong,Oh 한국지질과학협의회 2006 Geosciences Journal Vol.10 No.4

Constitutive equations for saturated hydraulic properties of deforming porous geologic media with compressible solid constituents

Jun-Mo,Kim 한국지질과학협의회 2006 Geosciences Journal Vol.10 No.2

A series of constitutive equations is presented toevaluate the changes in the saturated hydraulic properties (i.e.,porosity and saturated hydraulic conductivity) which result fromthe mechanical deformation of porous geologic media. The con-stitutive equation for the deformation-dependent porosity isderived from the relationship between the porosity and the volu-metric strain considering both solid skeleton and solid constituent(solid grain) to be compresible while the latter is les compress-ible. The constitutive equation for the deformation-dependent sat-urated hydraulic conductivity is then obtained by substituting theconstitutive equation for the deformation-dependent porosity intothe Kozeny-Carman equation assuming that the mechanicaldeformation of porous geologic media does not alter the shape ofthe pores since the individual solid grains are relatively incom-pressible compared with the solid skeleton.

Cretaceous thermal event around the Gongsuwon thrust in the northeastern Okcheon belt: evidence from Rb-Sr geochronology of Paleozoic sedimentary rocks

사공희,권성택,한래희,이진한 한국지질과학협의회 2006 Geosciences Journal Vol.10 No.1

Land-ocean interaction of carbon cycle and bio-diversity change during the Cretaceous in Asia

Graciano,P.,Yumul,,Jr.,Hiromichi,Hirano,Yong,Il,Lee 한국지질과학협의회 2006 Geosciences Journal Vol.10 No.3