The August 2, 2007, Nevelsk earthquake: Instrumental data analysis     

Ch. U. Kim  V. I. Mikhailov  R. S. Sen  Ye. P. Semenova 《Russian Journal of Pacific Geology》2009,3(5):412-423

A catalogue of aftershocks of the 2007 Nevelsk earthquake (M _w = 6.2) was prepared on the basis of the data from the local network of digital seismic stations established on the southern part of Sakhalin Island. The parameters of the aftershock hypocenters were determined using the method of the seismic wave travel time inversion. The errors in the determination of the coordinates of the seismic events were analyzed. The particularities of the spatiotemporal distribution of the aftershocks in the source zone of the earthquake were established. It was shown that a strong aftershock was a subsource earthquake with its own source zone. This explains the disagreement between the energetic characteristics and the size of the aftershock zone of the Nevelsk earthquake.  相似文献   

Dynamic freshwater–saline water interaction in the coastal zone of Jeju Island, South Korea     

Kue-Young Kim  Yoon-Suk Park  Gee-Pyo Kim  Ki-Hwa Park 《Hydrogeology Journal》2009,17(3):617-629

Freshwater–saline water interactions were evaluated in a coastal region influenced by external forces including tidal fluctuations and seasonal rainfall variations. Five different coastal zones were considered on Jeju Island, South Korea, and electrical conductivity (EC) profiles from the monitoring wells were examined to identify the configuration of the freshwater–saline water interface. There appeared to be discrepancies among EC profiles measured at different points in time. To analyze the dynamic behavior of freshwater–saline water interactions, groundwater level measurements and multi-depth EC and temperature probes were used to obtain time-series data; the data showed that water level, EC and temperature were influenced by both tidal fluctuations and heavy rainfall. The effects of oceanic tide on EC and temperature differed with depth due to hydraulic properties of geologic formations. A spectral filter was used to eliminate the effects of tidal forces and provide information on the influence of heavy rainfall on water level, EC and temperature. Heavy rainfall events caused different patterns and degrees of variation in EC and temperature with depth. The time-series data of EC and temperature in the subsurface at various depths enable greater understanding of the interaction processes between fresh and saline water.  相似文献   

Dinoflagellate Cysts in Coastal Sediments as Indicators of Eutrophication: A Case of Gwangyang Bay,South Sea of Korea   总被引：1，自引：0，他引：1  

So-Young Kim  Chang-Ho Moon  Hyun-Jin Cho  Dhong-Il Lim 《Estuaries and Coasts》2009,32(6):1225-1233

Diatom densities in the surface water and dinoflagellate cysts in bottom sediments of Gwangyang Bay were studied to determine changes in the phytoplankton community structure in response to anthropogenic eutrophication and to assess the use of dinoflagellate cysts as indicators of coastal eutrophication. Our results show that, in nutrient-enriched environments, diatoms are particularly benefited from the nutrients supplied and, as a consequence, heterotrophic dinoflagellates that feed on the diatoms can be more abundant than autotrophic dinoflagellates. In short-core sediment records, a marked shift in autotrophic–heterotrophic dinoflagellate cyst compositions occurred at a depth of approximately 9–10 cm corresponding to the timing of the 1970s industrialization around Gwangyang Bay. This tentatively indicates that diatom and dinoflagellate communities here have undergone a considerable change mainly due to increased nutrient loadings from both domestic sewage effluent and industrial pollution. Our study suggests a possible potential use of dinoflagellate cysts in providing retrospective information on the long-term effects of coastal eutrophication.  相似文献   

Aggregation of montmorillonite and organic matter in aqueous media containing artificial seawater     

Yoko Furukawa  Janet L Watkins  Jinwook Kim  Kenneth J Curry  Richard H Bennett 《Geochemical transactions》2009,10(1):2-11

Background  

The dispersion-aggregation behaviors of suspended colloids in rivers and estuaries are affected by the compositions of suspended materials (i.e., clay minerals vs. organic macromolecules) and salinity. Laboratory experiments were conducted to investigate the dispersion and aggregation mechanisms of suspended particles under simulated river and estuarine conditions. The average hydrodynamic diameters of suspended particles (representing degree of aggregation) and zeta potential (representing the electrokinetic properties of suspended colloids and aggregates) were determined for systems containing suspended montmorillonite, humic acid, and/or chitin at the circumneutral pH over a range of salinity (0 – 7.2 psu).  相似文献   

Inter-station correlation and estimation errors of areal average rain rate     

Chulsang Yoo  Ungtae Kim  Kyoungjun Kim  Keewook Kim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(2):143-157

In this study an equation for estimating the error involved in the areal average rain rate considering the inter-station correlation was derived and applied for two cases: the first compared two storm events with different inter-station correlations, and the second evaluated the seasonal variation of estimation error of monthly rainfall. Similar cases, but without considering the rainfall seasonality, were also investigated for the comparison. This study was applied to the Geum River Basin with 28 rain gauge measurements, each having more than 30 years of rainfall data. A summary of the application results follows: (1) When considering the inter-station correlation, the estimation error involved in the areal average rain rate became significantly decreased proportional to the inter-station correlation. (2) The estimation error of monthly areal average rainfall showed strong seasonality with high ones during the wet season and lower ones during the dry season. (3) The estimation error was well proportional to the areal average rain rate as well as to its standard deviation. The ratio of estimation error to the areal average rain rate itself was estimated to be about 0.1 for the case of assuming no inter-station correlations, but decreased to 0.06 for the case of considering the inter-station correlations between measurements. (4) The relation between the standard deviation of areal average rain rate and the estimation error became much stronger than that between the areal average rain rate itself and the estimation error. The ratio of estimation error to the standard deviations of rain rate amount was estimated to be about 0.2 for the case of assuming no inter-station correlations, but decreased to 0.1 for the case of considering the inter-station correlations. This relation was found to be valid for any case of accumulation time such as in daily, monthly, or annual rainfall data.  相似文献   

Constraints from precariously balanced rocks on preferred rupture directions for large earthquakes on the southern San Andreas Fault     

Kim Olsen  James Brune 《Journal of Seismology》2008,12(2):235-241

We have compared near-fault ground motions from TeraShake simulations of M_w7.7 earthquake scenarios on the southern San Andreas Fault with precariously balanced rock locations. The TeraShake scenarios with different directions of rupture generate radically different ground motions to the northwest of the Los Angeles Basin, primarily because of directivity effects, and thus provide constraints on the ground motion and rupture direction for the latest (1690) large event on that section of the San Andreas Fault. Due to the large directional near-field ground motions predicted by the simulations, we expect the precariously balanced rocks to be located primarily in the backward rupture direction or near the epicenter. Preliminary results favor persistent nucleation at or slightly northwest of the San Gorgonia Pass fault zone for large earthquakes on the southern San Andreas Fault.  相似文献   

Influence of climate variation on seasonal precipitation in the Colorado River Basin   总被引：1，自引：1，他引：0  

Tae-Woong Kim  Chulsang Yoo  Jae-Hyun Ahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(3):411-420

This study analyzed the influence of large-scale climate pattern on precipitation in the Colorado River Basin. Large-scale climatic oscillations, like ENSO, PDO, NAO, and the global warming trend are associated with regional hydrologic variation. Ten types of climate indices were gathered and analyzed to investigate their influence on seasonal precipitation variation in the basin based on a linear correlation analysis and an influence index analysis. The influence index was developed in this study to measure the effect of climate variation on the seasonal precipitation in the basin. The statistical evidence achieved in this study confirms that the Colorado River Basin is subjected to the phase of climate variation. The strength of the seasonal response of precipitation to the climate variation varies in different localities in the basin. The methods of analysis used in this study were proposed in the hope that progress in understanding and modeling dynamic climatic systems can result in developing a valuable long-term forecasting model for water resources management.  相似文献   

Integrated watershed management for mitigating streamflow depletion in an urbanized watershed in Korea   总被引：3，自引：0，他引：3  

Kil Seong Lee  Young-Oh Kim 《Physics and Chemistry of the Earth》2008,33(5):382-394

A systematic, seven-step approach to integrated watershed planning and management is applied to an urbanized watershed, the Anyangcheon (AY) watershed in Korea which consists of (1) understanding watershed components and processes, (2) identifying and ranking problems to be solved, (3) setting clear and specific goals, (4) developing a list of management options, (5) eliminating infeasible options (6) testing the effectiveness of remaining feasible options, and (7) developing the final options. Watershed characteristics, water quantity and quality simulations with SWAT and PLOAD models, and the developed problem indices of PFD (Potential Flood Damage), PSD (Potential Streamflow Depletion), and PWQD (Potential Water Quality Deterioration) identify that streamflow depletion is more serious than flood risk and water pollution in the study watershed (Steps 1 and 2). Instreamflow requirements, which are the maximum value of the average low flow and the fish flow, are estimated using regional regression and the software PHABSIM (Step 3). Feasible solutions that improve the depleted streams are listed and screened qualitatively against technical, economical, and environmental criteria (Steps 4 and 5). Effectiveness of the remaining 14 feasible alternatives are then analyzed using SWAT (Step 6) and alternative evaluation index (AEI) and their priority ranks are determined against an evaluation criterion that uses the concept of pressure, state, and response (Step 7).  相似文献   

Flow Characteristics of Microbubble Suspensions in Porous Media as an Oxygen Carrier     

Yong Ju Choi  Joo Young Park  Young‐Jin Kim  Kyoungphile Nam 《洁净——土壤、空气、水》2008,36(1):59-65

Microbubble suspensions were generated as an oxygen carrier for aerobic biodegradation, and their flow characteristics in porous media were investigated. Commercial surfactants including sodium dodecyl sulfate (SDS), and dodecylethyldimethylammonium bromide (DEDAB), saponin (a natural surfactant), and collagen (a protein hydrolysate) were examined as base materials for generating microbubble suspensions. Among them, 2×CMC (critical micellar concentration) of SDS, DEDAB, and saponin developed microbubble suspensions with the highest gas hold‐up and half‐drainage time. Visualization of the flow patterns in sand showed that the microbubble suspensions were separated into a liquid and gas phase directly after injection, showing much faster movement of liquid phase flow. The gas front of the microbubble suspensions flowed in a plug‐flow manner, particularly in cases of SDS and DEDAB. The experimental results from both homogeneous and heterogeneous cells confirmed that the microbubble flow could overcome the heterogeneity in porous media. However, the plug‐flow characteristics and flow propagation of the microbubble suspensions to the low‐permeability zone was accompanied by a large pressure drop, which needs to be considered for future field application.  相似文献   

Sulfur hexafluoride as a complementary method for measuring the extent of point-source thermal effluents     

Kim TW  Lee K  Park KT  Kim M 《Marine pollution bulletin》2008,56(7):1294-1302

The transport and dilution dynamics of power-plant thermal effluent were measured for 10 consecutive days, between 25 June and 4 July 2006, by concurrently mapping the daily distributions of seawater temperature and concentrations of deliberately released sulfur hexafluoride (SF(6)) within the tidal Kwangyang Bay on the southern coast of Korea. Estimates of the daily extent of the thermal plume based on temperature and SF(6) data showed distinct differences. These differences were particularly pronounced on sunny days during which solar radiation significantly heated river or bay waters moving across the tidal flats; in these cases, the estimates based on seawater temperature data were consistently greater than those based on SF(6) data, indicating considerable overestimates of the extent of the thermal plume when temperature data were used. The present results indicate that the concurrent use of seawater temperature and SF(6) data is a powerful method in determining the extent of thermal plumes, particularly for shallow areas in which the effects of solar heating lead to large uncertainties in temperature-based estimates.  相似文献