Relationship between Crustal 3D Density Structure and the Earthquakes in the Longmenshan Range and Adjacent Areas

Abstract: This paper presents the 3D density structure of crust in the Longmenshan range and adjacent areas, with constraints from seismic and density data. The density structure of crust shows that the immense boundary plane of density distribution in relation to the Longmeshan fault belt is extended downward to ~80 km deep. This density boundary plane dips towards the northwest and crosses the Moho. With the proximity to the Longmenshan fault belt, it has a larger magnitude of undulation in the upper and middle crust levels. Density changes abruptly across Longmeshan fault belt. Seismic data show that most of the earthquakes in the Longmenshan area after the 2008 Ms8.0 Wenchuan Earthquake occurred within the upper to middle crust. These earthquakes are clearly distributed in the uplifted region of the basement. A few of them occurs in the transitional zone between the uplifted and subsided areas. But most of the earthquakes distributes in transitional zone from subsided to uplifted areas in the upper and middle crust where relatively large density changes occurr The 3D density structure of crust in the Longmenshan and adjacent areas can thus help us to understand the pattern of overthrusting from the standpoint of deep crust and where the earthquakes occurred.     

玉树地震震源区速度结构与余震分布的关系

利用玉树震区21个应急流动地震台站和青海省地震台网固定地震台站的观测数据,采用双差层析成像方法,对2010年4月14日至6月15期间发生的地震进行了重定位,并反演得到了玉树地震震源区的三维速度结构.重定位结果揭示余震主要沿NW向成窄带状分布在断层的两侧,表明脆性破裂应力释放主要集中于一个狭窄的区域内.在西北端,余震偏离玉树—甘孜断裂分布,在SW向也有分布,推测可能与南西向次级断裂有关.双差层析成像得到的速度结构在浅部与地表地质构造相一致,中上地壳的速度结构显示巴颜喀拉地块为高速异常,羌塘地块为低速异常.玉树地震余震分布与特定的速度结构存在相关性：主震发生在高低速过渡带偏高速体的一侧,余震主要分布在高速体外围,高速体内部几乎没有余震分布.一般说来,中上地壳的高速体通常具有较高的强度,可以积累较强的孕震能量.主震发生后,高速体内积累的弹性能量向周边释放,可能是导致高速体周边余震发生的主要原因.     

平顶山矿区矿井突（涌）水水源判别模式

对在平顶山矿区所采集的地下水样品进行了多元统计分析,以识别一些来源不清的样品归属,建立该区突（涌）水水源判别模型。选择水中６大离子为变量,对３７个水样进行了Ｑ型聚类分析和阳离子三角形分析;以聚类分析所得的结果为基础,应用判别分析方法建立了该矿区寒武系灰岩水、薄层灰岩水（Ｌ２）和砂岩水３类判别模型,并应用马氏距离作Ｆ检验和归属概率“检验”,结果表明所建立的判别模型是有效的。     

浅析广义干旱与狭义干旱的联系与区别

指出干旱研究的基础是以区域水资源承载力为前提。利用陆地水文学知识分析了自然界水循环运动的每个环节和特点,剖析了水资源承载力在陆面蒸发和径流衰退过程中形成干旱的机制。定义了广义干旱,并简析了与气象、农业等各种狭义干旱的区别与联系。强调了陆地水文学是唯一可以给干旱以科学、严谨和充分定义的学科。     

“一带一路”区域可持续发展生态环境遥感监测

2013年9月和10月,习近平主席在出访中亚和东南亚国家期间,先后提出了共建"丝绸之路经济带"和"21世纪海上丝绸之路"(简称"一带一路")的重大倡议。要全面保护"一带一路"区域生态环境,实现2030年可持续发展目标,是一个具有挑战性的问题。遥感技术对生态环境监测与评价发挥着十分重要的作用。本研究利用多尺度、多源遥感数据,对2015年"一带一路"区域的生态环境状况进行监测和分析,旨在提供可持续发展目标生态环境遥感监测的本底。本文选取了几个重要的生态环境方面开展监测与分析,主要包括宏观生态系统结构和植被状况、太阳能资源分布、水资源平衡、主要生态环境限制因素对经济走廊建设的影响、主要城市生态环境质量等。监测区域覆盖亚洲、非洲、欧洲和大洋洲的陆上区域。研究结果为生态环境评价与保护提供了有效的决策依据,有助于"一带一路"建设积极推进。     

矩形基坑涌水量计算方法研究

通过对矩形基坑渗流模型的理论研究及实践分析,以达西定律及裘布依假定为理论依据,推导了潜水完整矩形基坑涌水量的计算方法。并通过工程实例,分析了本文计算方法、大井法、瀑布法适用的基坑涌水量计算类型,认为本文计算方法更适合于长宽比较大时矩形基坑涌水量的计算。     

博斯腾湖向塔里木河输水风险分析方法

为了拯救塔里木河下游生态环境，塔里木河流域管理局根据博斯腾湖从1999年到2003年处于丰水期，湖泊处于高水位的有利时机，从2000年5月到2003年6月实施5次向塔里木河下游生态应急输水，结束塔里木河下游300多km河道近30年的断流历史。现在的问题是“博斯腾湖向塔里木河生态输水能否持续?”，“保证可持续输水的风险有多大?”本文以解决此问题为实例，介绍一般水库调节计算和水库特征水位确定方法；主要探讨水库(湖泊)向下游输水可持续性风险分析问题，提出的方法称为“水库输水可持续性风险计算时历试算法”，简称为“试算法”(T＆E方法)；并将此方法应用于实例中，计算博斯腾湖向塔里木河下游输水的可持续风险。     

2018?2019年舟山近海浮游动物群落结构春季年际变化及其与水团的关系

根据2018?2019年春季两个航次在舟山近海进行的浮游生物调查结果,对舟山近海的浮游动物群落结构(类群组成、优势种数量)年际变化进行了研究,利用典范对应分析(Canonical Correspondence Analysis, CCA)研究了两年春季浮游动物类群组成差异、优势种变化的原因,初步探讨了春季浮游动物群落结构动态变化的机制。结果表明:根据表层温度(Sea Surface Temperature,SST)、表层盐度(Sea Surface Salinity,SSS)的聚类分析,将该区域分为3个水团:杭州湾内水团(I区)、舟山本岛上升流水团II区)、舟山近海水团(III区)。不同水团对浮游动物类群组成影响显著,引起2018年和2019年春季3个水团区差异的主要贡献种(贡献率>10%)均为中华哲水蚤,同一水团两年间年际差异的贡献种如下:I区为捷氏歪水蚤(56.91%)和真刺唇角水蚤(12.34%);II区为中华哲水蚤(72.64%)、五角水母(13.35%);III区为中华哲水蚤(41.93%)、夜光虫(22.94%)。CCA分析表明,第1 CCA轴(CCA1)和第2 CCA轴(CCA2)共解释了两年春季浮游动物优势种累计方差的46.14%和物种?环境累计方差的97.82%。CCA1主要反映了空间(近海水团和湾内水团)的差异。CCA2主要反映了2018年和2019年站位的年际差异。盐度是影响春季浮游动物群落结构空间差异的主要因素,而温度、叶绿素a浓度是春季浮游动物群落结构年际差异的主要因素。     

郯庐断裂带南段新活动性的初步研究

由于郯庐断裂带南段的第四纪地层不发育,尽管断裂构造岩松散而未固结成岩,也难以应用地层变位法来确定它的最新活动时代和活动方式。笔者在发育断层泥的断裂露头剖面上,采集断层泥样品9个,通过扫描电镜——石英碎砾刻蚀形貌法来确定它的新动活性。根据石英碎砾的刻蚀形貌类型判定断层的最新活动时代和活动方式;蠕滑?粘滑?从而确定郯庐断裂带南段的最新活动时代在N_2—Q_1或Q_2,活动方式以粘滑为主。     

Impact of soil and water conservation measures on catchment hydrological response—a case in north Ethiopia

Impact studies of catchment management in the developing world rarely include detailed hydrological components. Here, changes in the hydrological response of a 200‐ha catchment in north Ethiopia are investigated. The management included various soil and water conservation measures such as the construction of dry masonry stone bunds and check dams, the abandonment of post‐harvest grazing, and the establishment of woody vegetation. Measurements at the catchment outlet indicated a runoff depth of 5 mm or a runoff coefficient (RC) of 1·6% in the rainy season of 2006. Combined with runoff measurements at plot scale, this allowed calculating the runoff curve number (CN) for various land uses and land management techniques. The pre‐implementation runoff depth was then predicted using the CN values and a ponding adjustment factor, representing the abstraction of runoff induced by the 242 check dams in gullies. Using the 2006 rainfall depths, the runoff depth for the 2000 land management situation was predicted to be 26·5 mm (RC = 8%), in line with current RCs of nearby catchments. Monitoring of the ground water level indicated a rise after catchment management. The yearly rise in water table after the onset of the rains (ΔT) relative to the water surplus (WS) over the same period increased between 2002–2003 (ΔT/WS = 3·4) and 2006 (ΔT/WS >11·1). Emerging wells and irrigation are other indicators for improved water supply in the managed catchment. Cropped fields in the gullies indicate that farmers are less frightened for the destructive effects of flash floods. Due to increased soil water content, the crop growing period is prolonged. It can be concluded that this catchment management has resulted in a higher infiltration rate and a reduction of direct runoff volume by 81% which has had a positive influence on the catchment water balance. Copyright © 2010 John Wiley & Sons, Ltd.