2001年2月23日四川省雅江-康定6.0级地震宏观烈度考察及发震构造背景刍议

2001年2月23日在四川省境内发生了6.0级地震,其宏观震中位于雅江县与康定县之间的高山峡谷地带.极震区烈度达Ⅷ度,Ⅷ度区、Ⅶ度区和Ⅵ度区面积分别为180、1472和3998km2,等震线分布总体形态呈椭圆形,长轴近南北向.震区建筑物普遍受损,山地灾害较为严重.据初步分析认为,此次地震的发生与理塘断裂和玉龙西断裂的长期活动有关,主干断裂活动造成地壳应力调整和集中,最终在块体内部的次级断裂上释放而发生地震.     

2001年四川省雅江-康定6.0级地震烈度考察及发震构造背景雏议

2001年2月23日四川省发生的6.0级地震，其宏观震中位于雅江县与康定县之间的高山峡谷地带．极震区烈度可达Ⅷ 度，Ⅷ 度区、Ⅶ 度区和Ⅵ 度区面积分别为180km2，1472 km2和3998 km2，等震线分布总体形态呈椭圆形，长轴近南北向．震区建筑物普遍受损，极震区山地灾害较为严重．初步分析认为，此次地震的发生与理塘断裂和玉农希断裂的长期活动有关，主干断裂活动造成的地壳应力调整和集中，最终在块体内部的次级断裂上释放而产生地震．      

2001年2月23日四川雅江—康定6．0级地震宏观烈度考察及发震构造背景刍议

2001年2月23日在四川省境内发生了6．0级地城, 宏震中位于雅江县与康定县之间的高山峡谷地带。极震区烈度达Ⅷ度，Ⅷ度区，Ⅶ度区和Ⅵ度区面积分别为180，1472和3998km^2，等震线分布总体形态呈椭圆形，长轴近南北向。震区建筑物普遍受损，山地灾害较为严重。据初步分析认为，此次地震的发生与理塘断裂和玉龙西断裂的长期活动有关，主干断裂活动造成地壳应力调整和集中，最终在块体内部的次级断裂上释放而发生地震。     

1954年甘肃山丹7(1/4)级地震史料补遗

在归纳1954年山丹71/4级地震已有地震史料的基础上,根据新获得的朱允明(2006)《山丹地震考察笔记》的详细考察资料,按照《新中国地震烈度表》重新评定了本次地震中各考察点的地震烈度,重新绘制了该地震的等震线图。其中,极震区Ⅸ—Ⅹ度区长轴方向为北西向,呈扁椭圆形,长轴直径约40km;Ⅷ度区南西侧为山丹盆地,第四纪沉积较厚,地震烈度衰减缓慢,因此,Ⅷ度区等震线向南明显突出。1954年山丹71/4级地震极震区位于龙首山北缘断裂西段,大致与该断裂的包代河-黑头山段相吻合,综合分析认为,该段断裂是本次地震的主发震断层,而破喇嘛顶西缘断裂和毛湖洞断裂是重要的参与断裂。     

1986年8月26日门源6.4级地震考察初步总结

考察结果表明,地震宏观震中位于北纬37°37′、东经101°38′,震中烈度约Ⅷ度、震源深度13公里。Ⅵ度区面积为2600平方公里,长轴方向为N55°W。发震断层为冷龙岭山脊断层,该断层走向为N60°W,属于北祁连断裂带中段的组成部份。文中初步总结了有关地震前兆资料和震区宏观异常现象,对震区地震趋势进行了初步讨论。     

2013年芦山MS7.0地震震源参数特征 及近断层强地面运动初步估计

2013年4月20日在我国四川省雅安市芦山县发生了M_S7.0地震, 破坏最严重的宝兴、 芦山等极震区烈度达到Ⅷ—Ⅸ度. 该文针对芦山M_S7.0地震震源参数的特征, 结合相关经验关系, 对本次地震的震源特征进行了初步分析. 结果表明, 芦山M_S7.0地震为断层动态摩擦过程中的应力下调模式. 进一步应用Brune圆盘模型对芦山M_S7.0地震近场强地面运动的理论值进行估算, 并基于加速度和速度的估算结果计算极震区的最大烈度, 约为Ⅷ—X度, 与实测的极震区最大烈度Ⅸ度较为接近. 选取宝兴和芦山为特征计算点, 构建动态复合震源模型, 对近断层区域内宝兴和芦山两个特征点进行了模拟计算. 模拟结果显示, 近断层区域强地面运动呈现持续时间短、 高频成分多等特征.      

2013年西藏左贡与芒康交界6.1级地震的房屋震害特征

2013年8月12日在西藏自治区左贡与芒康交界发生6.1级地震,该地震宏观震中位于左贡县田妥镇嘎益村-仁果乡吞永村一带,最大烈度Ⅷ度,但不构成Ⅷ度区.根据现场工作队所收集的资料,分析了震区各类房屋建筑的震害特征及其破坏原因,并根据此次地震对该地区房屋所造成的破坏程度提出了防震减灾研究建议,并强调了此类民居需要加强抗震设计.     

2012年新疆新源—和静M_S6.6地震极震区地质灾害特征研究

通过叙述2012年6月30日新源—和静MS6.6地震极震区内地震崩塌、滑坡、地裂缝和碎石流4种地震地质灾害规模、分布特征,结合震前极震区内地质灾害分布类型和特征,将震前与震后的地质灾害特征进行对比分析,认为虽然此次地震极震区烈度仅为Ⅷ度,但发生的地震裂缝与地震崩塌等地震地质灾害具有独特性,应与该地区的地貌、地层岩性有关。     

2003年10月25日民乐-山丹6.1、5.8级地震烈度和发震构造特征

2003年10月25日20时41分在甘肃省民乐县和山丹县境内发生了6．1、5．8级地震。现场考察宏观震中位于民乐县永固镇姚寨子村和山丹县霍城镇刘庄村一带；极震区烈度为Ⅷ度；发震断层为民乐-永昌隐伏断裂和童子坝河隐伏断裂。本分析了震区房屋建筑特征和抗震性能及烈度分区特征，探讨了地表变形分布与发震构造的关系。     

序言

正2016年1月21日,青海省海北藏族自治州门源回族自治县发生6.4级地震。此次地震震中位于门源县城附近,灾区极震区烈度Ⅷ度,造成青海省、甘肃省部分地区受灾。地震发生后,青海省地震局立即启动了地震应急Ⅱ级响应,派出多批次现场工作队伍连夜赶赴震区,迅速开展地震烈度调查、灾害损失评估、流动监     

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.