UNIFIED EARTHQUAKE CATALOG FOR CHINA’S SEAS AND ADJACENT REGIONS AND ITS COMPLETENESS ANALYSIS

China’s seas and adjacent regions are affected by interactions among the Eurasian plate, the western Pacific plate, and the Philippine Sea plate. Both intraplate and plate-edge earthquakes have occurred in these regions and the seismic activities are frequent. The coastal areas of China are economically developed and densely populated. With the development and utilization of marine energy and resources along with the development of national economy, the types and quantity of construction projects in the marine and coastal areas have increased, once an earthquake happens, it will cause huge damage and loss to these areas, therefore, the earthquake-related research for these sea areas cannot be ignored and the need for study on these areas is increasingly urgent. One type of essential basic data for marine seismic research is a complete, unified earthquake catalog, which is an important database for seismotectonics, seismic zoning, earthquake prediction, earthquake prevention, and disaster reduction. Completeness and reliability analysis of an earthquake catalog is one of the fundamental research topics in seismology.
At present, four editions of earthquake catalogs have been officially published in China, as well as the earthquake catalogue compiled in the national fifth-generation earthquake parameter zoning map, these catalogs are based on historical data, seismic survey investigations, and various instrumental observations. However, these catalogs have earlier data deadlines and contain the earthquake records for only the offshore regions of China, which are extensions of coastal land. Distant sea regions, subduction zones, and adjacent sea regions have not been included in these catalogs. Secondly, there were no cross-border areas involved in the compilation of earthquake catalogs in the past. It was not required to use magnitudes measured by other countries’ seismic networks and observation agencies to develop an earthquake catalog with a uniform magnitude scale, moreover, there was no formula suitable for the conversion of magnitude scale in China’s seas areas and adjacent regions. Little research has been conducted to compile and analyze the completeness of a unified earthquake catalog for China’s seas and adjacent regions. Therefore, in this study, we compiled earthquake data from the seismic networks of China and other countries for China’s seas and adjacent regions. The earthquake-monitoring capabilities of different sea areas at different time periods were evaluated, and the temporal and spatial distribution characteristics of epicentral location accuracy for China’s seas and adjacent regions were analyzed. We used the orthogonal regression method to obtain conversion relationships between the surface wave magnitude, body wave magnitude, and moment magnitude for China’s seas and adjacent regions, and established magnitude conversion formulae between the China Seismic Network and the M_L magnitude of the Taiwan Seismic Network and the M_S magnitude of the Philippine Seismic Network. Finally, we developed an earthquake catalog with uniform magnitude scales for China’s seas and adjacent regions.
On the basis of the frequency-magnitude distribution obtained from the magnitude-cumulative frequency relationship (N-T) and the Gutenberg-Richter(GR)law, we conducted a completeness analysis of the unified earthquake catalog for China’s seas and adjacent regions, Then, we identified the beginning years of each magnitude interval at different focal depth ranges and different seismic zones in the earthquake catalog.
This study marks the first time that a unified earthquake catalog has been compiled for China’s seas and adjacent regions, based on the characteristics of seismicity in the surrounding sea regions, which fills the gap in the compilation of the earthquake catalogue of China’s seas and adjacent areas. The resulting earthquake catalog provides a basis for seismotectonics, seismicity study, and seismic hazard analysis for China’s seas and adjacent regions. The catalog also provides technical support for the preparation of seismic zoning maps as well as for earthquake prevention and disaster reduction in project planning and engineering construction in the sea regions. In addition, by evaluating the earthquake-monitoring capability of the seismic networks in China’s seas and adjacent regions and analyzing the completeness of the compiled unified earthquake catalog, this study provides a scientific reference to improve the earthquake-monitoring capability and optimizing the distribution of the seismic networks in these regions.     

The main characteristics, problems, and prospects for Western European coastal seas

Located to the far West of Western Europe, France has a western maritime coastal zone of more than 3800 km, which is widely influenced by the North-eastern Atlantic. The English Channel, an epi-continental shallow sea with very strong tides, runs along 650 km of the French coast and 1100 km of the English coast. It is also a bio-geographical crossroad encompassing a much wider range of ecological conditions than other European seas. France's Atlantic coast north of the Gironde estuary is a succession of rocky and sandy shorelines, including a sizeable intertidal zone, a wide continental shelf, and two major estuaries (Loire and Gironde). South of the Gironde, the 260 km of coastline is low, sandy and straight, with a narrowing continental shelf further on South due to the presence of the Cape Breton canyon in the bathyal and abyssal zones. Interface between the continental and oceanic systems, these bordering seas--North Sea, English Channel and Atlantic Ocean--have been the subject of many recent research programmes (the European Mast-FLUXMANCHE and INTERREG programmes; the national coastal environment programme and the LITEAU programme in France), designed to improve comprehension of the functions, production, and dynamics of these seas as well as their future evolution. Given the many conflicting practices in these littoral zones, integrated coastal zone management appears to be essential in order to cope with both natural phenomena, such as the infilling of estuarine zones, cliff erosion, and rising sea levels, and chronic anthropogenic pressures, such as new harbour installations (container dikes, marinas), sea aggregate extraction for human constructions, and offshore wind mill farms. This article provides as complete an overview as possible of the research projects on these bordering seas, both those that have recently been accomplished and those that are currently in progress, in order to highlight the main characteristics of these ecosystems and to underline the future challenges for European marine research in terms of the integrated coastal zone management of these highly significant coastal zones.     

Many-year variations in river delta structures

Data on several river deltas are used to analyze the regularities in their dynamics in the context of variations of water and sediment runoff, sea level, and hydroengineering activities in delta areas. The basis for this analysis includes the results of many-year studies of river deltas in Russia and the world. The specific features of the evolution of the structure and morphometry of bayhead deltas, forming in bays, lagoons, and estuaries are shown in the case of the Alikazgan delta in the Terek mouth area and the deltas of two watercourses in the Mississippi mouth area. Data on many-year variations of the morphometric characteristics of modern protruding deltas in open coastal zones are systematized, and the factors that have an effect on these changes are analyzed. The types of delta formation processes and the types of deltas are considered with regard to the factors involved. The majority of modern river deltas are found to slow down their progradation into seas under the effect of anthropogenic runoff decline; moreover, some deltas have started retreating and degrading.     

The need for international co-operation in the management of coastal environments

The coastal zones are areas of high biological productivity and intense human pressure. Environmental challenges arise from pollution and from urban and industrial development. Administrative, social and legal challenges centre upon the need for sound management of coastal zone resources, as an important component of national strategies for sustainability. A number of specific actions have been set out in Agenda 21, the principal product of the Earth Summit held in Rio de Janeiro in 1992. But these need to be carried forward within cross-sectoral, integrated coastal area management procedures. International action is also needed because marine ecosystems rarely coincide with national boundaries, and are affected by international economic, social and legal decisions.

International scientific co-operation on marine issues is already well established, and many regional action plans and Conventions have been adopted. Technological co-operation is less advanced. Such efforts need to be intensified, and continuously adapted. Sound plans for the future must be based on good science, critical economic evaluation of resources, sensitive evaluation of social and cultural factors and of the needs of local communities, evaluation of the risks of climate change, sea-level rise and other changes, and monitoring as a basis for continuing adaptation.     

Stack unit mapping of coastal aquifer to predict and control sea water intrusion using remote sensing and a geographical information system

Aquifers are inherently susceptible to contamination and coastal aquifers in specific are highly vulnerable to sea water intrusion. For efficient planning and management of coastal aquifers in Kayalpattu and Tiruchopuram villages, which extend over 4·05 km², it is essential to delineate and predict the extent of intrusion into the shallow aquifer. Management of ground water in coastal aquifers is composed of major elements that should be properly evaluated, and special attention is given to the sea water intrusion problem. Different data, like hydro‐geomorphological and depth‐wise iso‐apparent resistivity, are integrated spatially using a geographical information system. The stack‐unit mapping approach is used to delineate the zones with iso‐apparent resistivity of less than 10 Ω m have been found to be increasing in areal extent with reference to depth. Copyright © 2003 John Wiley & Sons, Ltd.     

Mapping groundwater discharge to a coastal lagoon using combined spatial airborne thermal imaging,radon (222Rn) and multiple physicochemical variables

Coastal lagoons are significant wetland environments found on coastlines throughout the world. Groundwater seepage may be a key component of lagoon water balances, though only a few studies have investigated large (>100 km²) coastal lagoons. In this study, we combined airborne thermal infrared imagery with continuous measurements of radon (²²²Rn—a natural groundwater tracer), conductivity, water temperature and dissolved oxygen to map groundwater seepage to a large coastal lagoon in New Zealand. We found evidence of seepage along the margins of the lagoon but not away from the margins. Our findings confirmed previously known seepage zones and identified new potential locations of groundwater inflow. Both point source and diffuse seepage occurred on the western and northwestern margins of the lagoon and parallel to the barrier between the lagoon and sea. These observations imply geologic controls on seepage. The combination of remote sensing and in-situ radon measurements allowed us to effectively map groundwater discharge areas across the entire lagoon. Combined, broad-scale qualitative methods built confidence in our interpretation of groundwater discharge locations in a large, dynamic coastal lagoon.     

Declines in oil-rates of stranded birds in the North Sea highlight spatial patterns in reductions of chronic oil pollution

Strandings of oiled seabirds are used to signal the problem of chronic oil pollution. Species-specific oil rates reflect the risk for marine birds to become oiled at sea. High oil rates were characteristic for seabirds common in areas with frequent oil spills; low oil rates for birds wintering away from the busiest shipping lanes. Declining trends in oil-rates were found, reflecting a reduction in the amount of oil intentionally discharged over the past 50 years. Spatial patterns in the risk to become oiled could be identified, when the winter distribution patterns of the affected birds were incorporated in the analysis. Declines in oil rates were most pronounced in coastal birds. These trends were consistent with tendencies to police nearshore waters more effectively than offshore waters. While levels of chronic oil pollution are much reduced, future emphasis should be to reduce chronic oiling more effectively in offshore waters.     

Effect of climate change on sea water intrusion in coastal aquifers

There is increasing debate these days on climate change and its possible consequences. Much of this debate has focused in the context of surface water systems. In many arid areas of the world, rainfall is scarce and so is surface runoff. These areas rely heavily on groundwater. The consequences of climate change on groundwater are long term and can be far reaching. One of the more apparent consequences is the increased migration of salt water inland in coastal aquifers. Using two coastal aquifers, one in Egypt and the other in India, this study investigates the effect of likely climate change on sea water intrusion. Three realistic scenarios mimicking climate change are considered. Under these scenarios, the Nile Delta aquifer is found to be more vulnerable to climate change and sea level rise. Copyright © 1999 John Wiley & Sons, Ltd.     

Biochemical Study of Brackish-Water Marine Ecosystems

The concentrations and the elemental and biochemical composition of dissolved and particulate organic matter (OM) characteristic of southern and Arctic seas are presented. The rate of OM transformation in the production–decomposition cycle and that of the phosphate cycle are estimated from the activity of the redox enzymes of the electron-transport system and that of phosphatase. Carbohydrates and protein are shown to be the main biochemical components in the water of all the seas under study in dissolved and particulate OM, respectively. The contribution of carbohydrates to particulate OM under the conditions of intense primary production is demonstrated to be comparable to that of protein. High concentrations of lipids are shown to be characteristic of the coastal ecosystems in the middle Caspian Sea and northwestern shelf of the Black Sea because of severe pollution in these areas. It is noted that at higher trophic levels, the ecosystem of the Caspian Sea intensely assimilates allochthonous OM, and that the Black Sea ecosystem transfers considerable amounts of OM to the hydrogen sulfide zone.     

Geomorphic controls and transition zones in the lower Sabine River

Instream flow science and management requires identification of characteristic hydrological, ecological, and geomorphological attributes of stream reaches. This study approaches this problem by identifying geomorphic transition zones along the lower Sabine River, Texas and Louisiana. Boundaries were delineated along the lower Sabine River valley based on surficial geology, valley width, valley confinement, network characteristics (divergent versus convergent), sinuousity, slope, paleomeanders, and point bars. The coincidence of multiple boundaries reveals five key transition zones separating six reaches of distinct hydrological and geomorphological characteristics. Geologic controls and gross valley morphology play a major role as geomorphic controls, as does an upstream‐to‐downstream gradient in the importance of pulsed dam releases, and a down‐to‐upstream gradient in coastal backwater effects. Geomorphic history, both in the sense of the legacy of Quaternary sea level changes, and the effects of specific events such as avulsions and captures, are also critical. The transition zones delineate reaches with distinct hydrological characteristics in terms of the relative importance of dam releases and coastal backwater effects, single versus multi‐channel flow patterns, frequency of overbank flow, and channel‐floodplain connectivity. The transitional areas also represent sensitive zones which can be expected to be bellwethers in terms of responses to future environmental changes. Copyright © 2007 John Wiley & Sons, Ltd.     

全球及中国近海海平面变化趋势研究进展及展望

海平面变化是全球气候系统变化的一个组成部分,是环境变化的重要指标,也会影响沿海区域及岛屿的生态环境甚至存亡.全球海平面变化由海水质量变化和比容海平面变化构成.海水质量变化主要是由于两极冰盖和高山区的冰川融化流入海洋所致;比容海平面变化是由海水的温度和盐度变化所引起的,其中温度变化是最主要的因素.本文介绍了海平面变化各种监测技术的发展过程,并对海平面变化的研究现状进行了总结.所有研究成果均表明,近100多年以来,全球海平面一直处于上升态势;近几十年以来,海平面呈现加快上升并且越来越快的趋势.目前仍然存在一些问题:人们还没有完全掌握海平面变化规律,对未来海平面变化预测有较大不确定性;深海缺乏实测数据;厄尔尼诺—南方涛动(ENSO)的变化规律以及对海平面的影响;GRACE陆地与海洋信号无法完全分离以及GRACE与GRACE-FO之间的一致性分析等.这些问题都需要进一步开展研究.     

The use of Lagrangian trajectories for the identification of the environmentally safe fairways

We propose and test a method for the optimisation of marine fairways to minimise the risk to high-value areas, based on statistical analysis of Lagrangian trajectories of current-driven pollution transport. The offshore areas are quantified according to the probability of pollution released in these areas to reach vulnerable regions. The method contains an eddy-resolving circulation model, a scheme for tracking of Lagrangian trajectories, a technique for the calculation of quantities characterising the potential of different sea areas to supply adverse impacts, and routines to construct the optimum fairway. The gain is expressed in terms of the probability of pollution transport to the nearshore and the associated time (particle age). The use of the optimum fairway would decrease the probability of coastal pollution by 40% or increase the average time of reaching the pollution to the coast from 5.3 to about 9 days in the Gulf of Finland, the Baltic Sea.     

我国海洋地学编图现状、计划与主要进展

我国海洋地质地球物理工作起步晚,整体调查程度较低,进一步加强我国海洋地学编图显得十分必要.我国实施的"海洋地质保障工程",将分"中国海陆"、"中国海及邻域"和"中国各海区"三个层次来进行地学编图.第一层次编制了空间重力异常图、布格重力异常图、磁力异常图、地震层析成像图、莫霍面深度图、地质图、大地构造格架图和大地构造格架演化图等8种图件.编图反映出中国海陆重力异常是"线性异常带纵横交错,块状异常区坐落其间"、重力梯级带主要为块体结合带;陆地磁力异常大致正负磁异常相间分布,海域北部为沟-弧-盆相关异常、南部磁条带异常;莫霍面总体特征为"东西分带,南北分块";地震层析成像反映出中国东部和西部岩石层厚度的差异以及上地幔软流层的分布特点;大地构造格架和演化图再现了块体体制向板块体制的转换过程.本次编图强调地球深部结构的变化对表层构造的关联,重视地球物理资料与地质构造的结合,以深-浅层结合来划分中国大地构造格架.已有成果表明,中国海陆大地构造格局可以用"块体构造学说"来描述.     

Petroleum hydrocarbons in the waters of major tributaries of the White Sea and its water areas: A review of available information

The White Sea is a natural analogue of arctic seas. The pollution of the sea by petroleum hydrocarbons is not high now. However, the load on sea ecosystem can increase in the nearest future because of the anticipated industrial development in its watershed, including an increase in oil, coal, and diamond production. The specific features of the nature of arctic marine systems (hydrological, ice, hydrobiological, hydrochemical, and radiation regimes), and the poor knowledge of the conditions of dispersion, transformation, and utilization of petroleum hydrocarbons in such seas make their ecological studies especially important. Petroleum hydrocarbon concentrations in the waters of tributaries and water areas of the White Sea (for 1980–2006 and 1989–2006, respectively) were evaluated using literary and authors’ data. Analysis of the collected materials shows that the majority of petroleum hydrocarbons enter the sea’s water areas with river runoff. Petroleum hydrocarbon concentrations were evaluated in major tributaries of the sea, including the rivers of Northern Dvina, Onega, Mezen, Niva, Kem, and Keret, delivering petroleum hydrocarbons into the bays of Dvina, Onega, Mezen, and Kandalaksha, water area near the Solovetskie Islands, and Chupa Bay, respectively (Bay — Gulf). Model calculations should yield within-year variations in petroleum hydrocarbon concentrations in different part of the sea (under a correctly specified load) and the conditions of their biotransformation and horizontal transport through the boundaries between areas within the sea.     

Coastal pollution hazards in southern California observed by SAR imagery: stormwater plumes, wastewater plumes, and natural hydrocarbon seeps

Stormwater runoff plumes, municipal wastewater plumes, and natural hydrocarbon seeps are important pollution hazards for the heavily populated Southern California Bight (SCB). Due to their small size, dynamic and episodic nature, these hazards are difficult to sample adequately using traditional in situ oceanographic methods. Complex coastal circulation and persistent cloud cover can further complicate detection and monitoring of these hazards. We use imagery from space-borne synthetic aperture radar (SAR), complemented by field measurements, to examine these hazards in the SCB. The hazards are detectable in SAR imagery because they deposit surfactants on the sea surface, smoothing capillary and small gravity waves to produce areas of reduced backscatter compared with the surrounding ocean. We suggest that high-resolution SAR, which obtains useful data regardless of darkness or cloud cover, could be an important observational tool for assessment and monitoring of coastal marine pollution hazards in the SCB and other urbanized coastal regions.     

Modeling fast ice formation and destruction in the Sea of Japan

The problems of parametric representation of the initial formation and the subsequent evolution of fast ice in freezing seas are discussed within the framework of the model of marine ice cover evolution. The mathematical form of this representation takes into account the processes of transformation of sea ice formations in open water areas in coastal regions into fast ice during its formation and inverse processes at the stage of its destruction. The parametric identification of the model was based on samples of long-term distributions of ice cover characteristics in the Sea of Japan, as well as the distributions of air temperature and wind speeds over sea water area. The model can be used to predict the state of fast ice in the ice cover of the Sea of Japan.     

Modeling of non‐point source nitrogen pollution from 1979 to 2008 in Jiaodong Peninsula,China

Efforts to reduce land‐based non‐point source (NPS) pollutions from watersheds to coastal waters are ongoing all around the world. In this study, annual yield of NPS nitrogen (NPS‐N) pollution in Jiaodong Peninsula, China from 1979 to 2008 was estimated. The results showed that: from 1979 to 2008, NPS‐N yields exhibited significant inter‐annual variations and an increasing trend on decadal scale. High NPS‐N yield was mainly found in east and south parts, as well as the urbanized coastal regions in Jiaodong Peninsula. Among the 32 river basins, the three largest basins yielded more than 41.16% of the NPS‐N. However, some small coastal watersheds along the South Yellow Sea and Jiaozhou Bay had higher per unit area yield. Most of the small watersheds characterized by seasonal runoff had coastal waters pertain to mild and moderate pollution levels. The ratio of watershed area to shoreline length and the up‐stream land use had significant impacts on NPS‐N flux through the shoreline. Among the four adjacent coastal areas of Jiaodong Peninsula, Jiaozhou Bay was the most noteworthy one not only because of high levels of land‐based NPS‐N pollution but also because of its nearly enclosed structure. The combination between integrated coastal zone management and integrated river basin management, land use planning and landscape designing in Jiaodong Peninsula is recommended. Copyright © 2013 John Wiley & Sons, Ltd.     

International scope of marine pollution damage

Increasing pollution of estuaries and coastal waters causes economic damage to fisheries, tourism and much else. Developing countries are not immune from this, and the growth of tourism as well as the shift of populations to the coast in many parts of the world make pollution control all the more urgent. The problem is an international one and demands international solutions, but before these are likely, a good deal more hard information will be needed.     

What dominates sea level at the coast: a case study for the Gulf of Guinea

Sea level variations and extreme events are a major threat for coastal zones. This threat is expected to worsen with time because low-lying coastal areas are expected to become more vulnerable to flooding and land loss as sea level rises in response to climate change. Sea level variations in the coastal ocean result from a combination of different processes that act at different spatial and temporal scales. In this study, the relative importance of processes causing coastal sea level variability at different time-scales is evaluated. Contributions from the altimetry-derived sea-level (including the sea level rise due to the ocean warming and land ice loss in response to climate change), dynamical atmospheric forcing induced sea level (surges), wave-induced run-up and set-up, and astronomical tides are estimated from observational datasets and reanalyses. As these processes impact the coast differently, evaluating their importance is essential for assessment of the local coastline vulnerability. A case study is developed in the Gulf of Guinea over the 1993–2012 period. The leading contributors to sea level variability off Cotonou differ depending on the time-scales considered. The trend is largely dominated by processes included in altimetric data and to a lesser extent by swell-waves run-up. The latter dominates interannual variations. Swell-waves run-up and tides dominate subannual variability. Extreme events are due to the conjunction of high tides and large swell run-up, exhibiting a clear seasonal cycle with more events in boreal summer and a trend mostly related to the trend in altimetric-derived sea-level.     

Jellyfish blooms in China: Dominant species, causes and consequences

Three jellyfish species, Aurelia aurita, Cyanea nozakii and Nemopilema nomurai, form large blooms in Chinese seas. We report on the distribution and increasing incidence of jellyfish blooms and their consequences in Chinese coastal seas and analyze their relationship to anthropogenically derived changes to the environment in order to determine the possible causes. A. aurita, C. nozakii and N. nomurai form blooms in the temperate Chinese seas including the northern East China Sea, Yellow Sea and Bohai Sea. N. nomurai forms offshore blooms while the other two species bloom mainly in inshore areas. Eutrophication, overfishing, habitat modification for aquaculture and climate change are all possible contributory factors facilitating plausible mechanisms for the proliferation of jellyfish blooms. In the absence of improvement in coastal marine ecosystem health, jellyfish blooms could be sustained and may even spread from the locations in which they now occur.