2012年震情述评

1 全球地震活动概况 据中国地震台网测定,2012年全球共发生7级以上地震20次(表1),其中包括2次8级以上地震,即2012年4月11日苏门答腊北部附近海域8.6级、8.2级地震(图1).与2011年相比,全球地震频次和能量释放明显减少.2012年全球7级以上地震活动有以下特点: 1.1 全球8级地震继续活跃 2012年全球共发生7级以上地震20次,比1900年以来的平均水平(18次/年)略高,与2011年(26次)相比,地震频次减少(图2).虽然2012年4月11日苏门答腊北部附近海域发生8.6级、8.2级地震,但与2011年(3月11日发生日本9.0级地震)相比,全球地震能量释放减少较明显.     

2010年震情述评

1 全球地震活动概况 据中国地震台网测定,2010年全球共发生7级以上地震28次(表1),最大地震为2月27日智利8.8级地震(图1).与2009年相比,全球地震频次和能量释放明显增加.2010年全球7级以上地震活动有以下特点： 2010年全球共发生7级以上地震28次,明显高于1900年以来的平均水平(18次/年),与2009年(20次)相比,地震频次明显增加.2010年南美板块西边界和印度-澳大利亚板块活跃,全球28次7级以上地震中有16次分布在印度-澳大利亚板块的北边界和东边界上,5次在南美板块西边界,4次在菲律宾板块边界,2次在北美板块边界,1次在中国青藏块体边缘地区,显示出空间分布相对集中的特点(图1).     

2003年震情述评

据我国台网测定，2003年全球共发生7级以上地震20次(表1)，最大地震为9月26日日本北海道8．0级地震(图1)。2003年全球地震活动仍维持前几年的活动格局。与2002年相比，地震频次和能量释放明显增高。2003年全球7级以上地震活动有以下特点：     

2009年震情述评

<正>1全球地震活动概况据中国地震台网测定,2009年全球共发生7级以上地震20次(表1),最大地震为9月30日萨摩亚群岛地区8.0级地震(图1)。与2008年相比,全球地震频次略有增加,释放的     

2006年震情述评

1全球地震活动概况据我国地震台网测定,2006年全球共发生7级以上地震15次(表1),最大地震为4月21日堪察加半岛8.0级和11月15日千岛群岛8.0级地震(图1)。与2005年相比,全球地震频次略有下降,能量释放明显降低。2006年全球7级以上地震活动有以下特点:表12006年全球7级以上地震目录     

2008年震情述评

1 全球地震活动概况 据我国地震台网测定,2008年全球共发生7级以上地震19次(表1),最大地震为5月12日四川汶川8.0级地震(图1).与2007年相比,全球地震频次下降,能量释放明显减少.2008年全球7级以上地震活动有以下特点.     

2005年震情述评

据我国地震台网测定，2005年全球共发生7级以上地震16次（表1），最大地震为3月29日印尼苏门答腊岛西北海域8．5级地震（图1）。与2004年相比全球地震频次和能量释放均有所降低。2005年全球7级以上地震活动有以下特点。     

2014年震情述评

<正>1全球地震活动概况据中国地震台网中心测定,2014年全球共发生7级以上地震13次(表1),其中包括1次8级以上地震,即2014年4月2日智利北部沿岸近海8.1级地震(图1)。2014年全球7级以上地震主要发生在环太平洋地震带,欧亚地震带活动较弱。与2013年相比,全球地震频次显著减少,能量释放略有降低。2014年全球7级以上地震活动有以下特点。     

2007年震情述评

1 全球地震活动概况 据我国地震台网测定,2007年全球共发生7级以上地震22次(表1),最大地震为9月12日印尼苏门答腊南部海中8.5级地震(图1).     

2005年地震活动概况

据我国地震台网测定, 2005年1-12月, 全球共发生MS7级以上地震16次, 低于1900年以来19次的年平均水平. 在空间上主要分布在西北太平洋地震带、东太平洋地震带和亚欧地震带(图1). 在时间上分布相对均匀, 除2月份和4月份没有发生7级以上地震外, 其它月份都有7级以上地震发生. 引人注目的是, 在苏门答腊地区发生了7次7级以上地震, 并且在印度板块的西触角处于10月8日发生了7.8级地震. 2005年1-12月, 全球7级以上地震释放的地震能量为5.29×1017 N·m, 处于自1900年以来的平均值3.853×1017 N·m之上.     

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.