郯庐地震带分段特征与小震序列活动分析

2008年汶川地震后,中国东部的地震活动水平上升,郯庐地震带内的小震序列活动增强显著。根据郯庐断裂带的分段特征,将郯庐地震带划分不同分段,结合分段内不同小震序列活动变化,研究不同分段的地震活动性参数异常,分析郯庐地震带分段之间的地震活动性的相互关系。     

辽宁地区中强以上地震时空分布特征

对辽宁地区M_s≥4 3/4级地震空间和时间分布特征进行了研究。通过研究认为,郯庐地震带北段是区内最重要的地震带,它控制了辽宁地区的地震活动;渤海北西向地震带和朝鲜新义州—釜山地震带的活动也将会对辽宁地区产生影响,地震活动网络结点、海城地震余震活动区等是未来容易发生中强以上地震的地区。通过熵谱分析、周期图等方法的研究,认为辽宁地区地震活动存在300多年的活动周期,未来百年将处于剩余应变释放期,活动水平不会太高。     

华北地区地震带活跃时段相关性分析

通过对1485年以来山西地震带、河北平原地震带及郯庐地震带5级以上地震时序的分析,认为这三个地震带活跃时段依次滞后,并且对滞后原因进行了探讨;之后对1900年以来三地震带作时序分析,认为山西地震带和河北平原地震带彼此交替活跃,郯庐带与河北平原带则同步活跃。山西地震带ML4级以上地震与山东内陆5级左右地震相关性较好,山东...     

郯庐带地震活动分析及未来地震危险性评估

从郯庐带整体地震活动特征出发,利用古登堡-里克特的震级与频度关系和地震时空扫描等方法对其危险性进行了分析,认为郯庐带在未来100年内仍有7级以上大地震发生的可能,其地点位于几个显著的北西向断裂与郯庐带交汇部位(如苏鲁皖交界,渤海湾地区等)。鉴于短期地震预测较难实现的现实条件下,提出了当前减轻地震灾害的对策建议:加强苏鲁皖交界区域的地球介质参数变化扫描研究;存在地震危险性的地区推进具有减震、隔震功能的地震安全社区建设工作。     

中国华北地区大地震复发周期及迁移特征

以古地震、历史地震和现代地震作为时间域,以华北地区、山西地震带、河北平原地震带和郯庐地震带为单元,分析和研究了华北地区大地震复发周期和迁移特征。在此基础上,讨论了华北地区地震活动的动力学问题、块体框动、地震迁移和地震活动趋势。     

郯庐地震带与邻带地震活动关系

本文对华北地区地震活动进行了期、带划分,并就各地震带的地震时空活动特征作了分析。找出该区大震发生的构造部位,分布方向及各带活动时间与华北地区的一致性。其中对郯庐地震带的地震活动与相邻地震带相关特性进行了重点研究。在此基础上对鲁南地区未来地震趋势作出判断。     

全球大于或等于8.5级特大巨震的周期性分析

采用方差分析叠加周期外推法对公元1897年以来全球MS≥8.5级特大巨震的周期性进行外推预测,通过严格理论计算,试图提出下一个MS≥8.5级特大巨震地震可能发生的时间段。分析了统计分析中可能存在的误差与其根源,但方法的意义在于应用统计理论分析把时间预测的定量化,对确定重点监视时段,从某种意义上有着一定的积极意义。另外通过分析提出的8个准周期值,这为研究地震机理,探索导致特大巨震发生的外部环境和演变规律的研究方向提供了参考。     

渤海及邻区地震地质、地球物理场和地震活动特征

对渤海及周转地区地质构造,地球物理场特征及地震活动特征进行了分析和研究。结果表明：该区域发育有ＮＮＥ、ＮＷ和ＮＷＷ向３组断裂,在渤海海域ＮＮＥ向的郯庐断裂被ＮＷＷ向断裂分割为３段,中段地震活动最强,发生过３次７级以上地震和３次６级以上地震,在空间上,地震活动可以划分为２个带,即郯庐地震带和燕山－渤海地震带。渤海中部地区热流值偏高,莫霍界面和康腊界面隆起,上地幔高层层埋深浅,为３０～５０ｍ。     

华北构造区主要地震带分段与强震活动

在华北构造区划分出银川—河套地震带、汾渭地震带、河北平原地震带、东秦岭—大别地震带、郯庐地震带和长江下游—黄海地震带等6个地震带,并依据地震带构造特征和地震活动的差异性,将其中汾渭地震带划分为延庆—代县段、原平—襄汾段和侯马—渭河段;河北平原地震带划分为三河—涞水段、唐山—邢台段和安阳—成武段;郯庐地震带划分为开原—辽东湾段、渤海段、潍坊—嘉山段和嘉山—广济段;银川—河套地震带初步划分为银川段和河套段.同时,对河北平原地震带南界及其与东秦岭—大别地震带的关系,地震带不同区段存在的主震型和多震型特点,以及可能发生强震的危险区段进行了初步探讨.     

华北构造区主要地震带分段与强震活动div

在华北构造区划分出银川——河套地震带、汾渭地震带、河北平原地震带、东秦岭——大别地震带、郯庐地震带和长江下游——黄海地震带等6个地震带,并依据地震带构造特征和地震活动的差异性,将其中汾渭地震带划分为延庆——代县段、原平——襄汾段和侯马——渭河段;河北平原地震带划分为三河——涞水段、唐山——邢台段和安阳——成武段;郯庐地震带划分为开原——辽东湾段、渤海段、潍坊——嘉山段和嘉山——广济段;银川——河套地震带初步划分为银川段和河套段．同时,对河北平原地震带南界及其与东秦岭——大别地震带的关系,地震带不同区段存在的主震型和多震型特点,以及可能发生强震的危险区段进行了初步探讨．      

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.