合肥市地壳浅部三维速度结构及城市沉积环境初探

合肥市位于合肥盆地东南缘,东侧紧邻郯庐断裂带,多条大型隐伏断裂穿过市区.为进一步认识合肥城市下方隐伏断裂的空间展布、性质,以及城市复杂的沉积环境,本文利用布设在合肥市区的58套三分量短周期地震仪组成的台阵,获得了37天的三分量连续波形数据,通过基于射线追踪的面波走时直接成像方法反演得到了合肥市地壳浅部0.6~3.6 km的三维剪切波速度结构,速度结构图像展现了地壳浅部的横向不均匀性和纵向成层性,揭示出NNE、NWW和近EW三组不同走向的隐伏断裂在城市地下浅部的构造特征.取得以下认识：（1）合肥市南、北方向在浅地表（2 km以内）存在显著速度差异,速度分界线位置与已知的近EW向的蜀山断裂一致,断裂南侧呈现低速凹陷,北侧则为高速隆起.低速中心深度达2~3 km,速度异常与该断裂在合肥盆地东部演化过程中的构造反转沉积了不同地层有关;（2）合肥市区存在明显的高速异常带,其走向、位置与穿过该区域的郯庐断裂带西支主干断裂相符,其中五河—合肥断裂在市区北部以东呈现低速凹陷特征,低速区范围与肥东凹陷晚白垩纪以来的沉积构造边界一致,认为肥东凹陷的最大沉积厚度可达2 km以上;（3）合肥市中心跨郯庐断裂带西支主干断裂之间呈现明显的凹、隆相间的复杂构造,推测其是在多组断裂的共同拉伸作用下形成的小型沉积盆地,沉积中心位于郯庐断裂带内部,最大厚度可达3~4 km.由于其展布方向在不同深度与该区域断裂的走向具有明显的相关性,推测不同深度的沉积形态与郯庐断裂带在不同时期的构造演化过程有关.

     

乌兰浩特地震台与阿尔山火山地震观测站面波震级偏差分析

为了提高乌兰浩特地震台、阿尔山火山地震观测站的震级精度,基于面波震级公式和残差统计方法,分别计算乌兰浩特台、阿尔山火山地震观测站与中国地震台网中心测定的面波震级之间的偏差,分析产生震级偏差的影响因素。结果表明:乌兰浩特台、阿尔山火山地震观测站测定的面波震级与中国地震台网发布震级的偏差平均值分别为0.19、0.17;震级偏差总体呈现随震级的增加而先增大后减少的趋势;阿尔山火山地震观测站震级偏差随震中距的增大而增大,而乌兰浩特台则先增大后减少。     

基于AVO正演模拟的自由表面多次波压制方法

针对SRME和Radon变换压制自由表面多次波的近道多次波残留和伤害有效波等问题,主要采用基于AVO属性分析的多次波剔除法对近道多次波进行压制,该方法在迭代更新过程中,受近道多次波影响容易出现更新误差,同时迭代更新降低计算效率.本文对基于AVO属性分析的多次波剔除法进行改进,利用中远道地震数据进行约束,通过AVO正演模...     

Effects of hydrocarbon physical properties on caprock’s capillary sealing ability

A new mechanics formula of caprock’s capillary sealing ability has been established in this paper, in which the boundary layer resistance was considered and characterized by starting pressure gradient. The formula shows that capillary sealing ability of caprock is determined not only by the capillary force of rock and the buoyancy of hydrocarbon column, but also by the starting pressure gradient of hydrocarbons and the thickness of caprock. The buoyancy of hydrocarbon column, the starting pressure gradient of hydrocarbon, and the capillary force of caprock are affected by hydrocarbon density, hydrocarbon viscosity, and hydrocarbon-water interface tension respectively. Based on hydrocarbon property data of reservoirs of Jiyang Depression and equations from literature, the effects of hydrocarbon density, hydrocarbon viscosity, and hydrocarbon-water interface tension on the sealing ability of caprock are analyzed. Under formational conditions, the sealing ability of oil caprock can vary up to dozens times because of the variations of the oil density, oil viscosity, and oil-water interface tension. Thus, the physical characters of hydrocarbon should be considered when evaluating the capillary sealing ability of caprocks. Study of the effects of physical characters on sealing ability of caprock can provide guidance to exploring special physical property hydrocarbon resources, such as viscous oils, and hydrocarbon resources in special pressure-temperature environments.     

1954年7月31日腾格里沙漠北7级地震

1954年7月31日,腾格里沙漠北发生7级地震,这是位于蒙、甘交界地区的一次破坏性强震。对这次地震的参数、震源机制、地震序列、地震烈度和灾害进行了研究,讨论了沙漠地震次生和衍生灾害特征,并从动力环境、地震孕育和发生相关地质单元的角度,探讨了成因。在此基础上,提出了保护沙漠地震区生态对防震减灾的现实意义和沙漠地震科学考察的建议。     

Study on Potential Strong Earthquake Risks Around the Mabian Area,Southern Sichuan

Based on seismic data from the regional network for the last 34 years,we analyzed the present fault behavior of major fault zones around the Mabian area,southern Sichuan,and identified the risky fault-segments for potential strong and large earthquakes in the future.The method of analysis is a combination of spatial distribution of b-values with activity background of historical strong earthquakes and current seismicity.Our results mainly show:(1) The spatial distribution of b-values indicates significant heterogeneity in the studied area,which reflects the spatial difference of cumulative stress levels along various fault zones and segments.(2) Three anomalously low b-value areas with different dimensions were identified along the Mabian-Yanjin fault zone.These anomalies can be asperities under relatively high cumulated stress levels.Two asperities are located in the north of Mabian county,in Lidian town in western Muchuan county,and near Yanjin at the south end of the fault zone.These two areas represent potential large earthquake seismogenic sites around the Mabian area in the near future.Besides them,the third relatively smaller asperity is identified at southern Suijiang,as another potential strongearthquake source.(3) An asperity along the southwestern segment of the Longquanshan fault zone indicates the site of potential moderate-to-strong earthquakes.(4) The asperity along the segment between Huangmu town in Hanyuan county and Longchi town in Emeishan city on Jinkouhe-Meigu fault has potential for a moderate-strong earthquake.     

黄土高原大理河流域水沙耦合模型应用研究

水沙模型是定量描述水沙关系及水沙规律的重要工具,现阶段国内外对于水沙模型的研究大都为基于某个典型流域的经验统计模型或基于流域大量基础资料的物理模型,极大限制了其使用范围及模拟精度.本文建立了结构与参数均具有物理意义的流域水沙耦合物理概念模型,其优点是物理概念清楚,模拟精度高,实用性强,易于深入研究泥沙基本规律.该模型将概念性水文模型和泥沙模型耦合,提出水流挟沙能力和土壤抗侵蚀能力概念,用对数曲线近似描述流域土壤抗侵蚀能力的空间变异性,在拜格诺河道水流悬移质泥沙公式基础上建立概念性沟蚀产沙公式,参照水流汇集相似性建立泥沙汇集演算公式.选取黄河中游大理河流域4个不同流域尺度的实际流域对模型进行应用检验,模拟结果表明,该模型的水流泥沙两部分均有很高的模拟精度,可以很好地模拟黄河中游地区不同流域尺度和年际尺度上的洪水过程和泥沙产生及输移过程,充分证明了该模型结构、参数和计算方法的合理性,可用于定量分析流域内各项水保措施的减水减沙效益及水沙关系变化趋势,对该模型的推广应用可做进一步分析研究.     

全新世以来东北地区沼泽湿地发育过程及其对气候变化的响应

沼泽湿地是陆地生态系统的重要组成部分,在维护区域环境稳定中起着重要作用.随着社会经济的发展,人类活动导致湿地大面积退化和消失,严重影响了区域生态安全;恢复退化湿地已成为各国政府和学者关注的焦点.而了解历史时期沼泽湿地发育过程及影响因素则是建立合理湿地恢复目标的重要前提.东北地区是我国最大的沼泽湿地集中分布区,其中70%的湿地面临不同程度的退化威胁;但由于数据的缺乏,东北地区沼泽湿地发育过程及其与气候变化的关系仍不清楚.基于此,本研究系统分析了全新世以来东北地区沼泽湿地形成发育的动态变化过程,并探讨了东北地区不同区域沼泽湿地的发育规律及其对气候变化的响应机理.研究发现东北地区沼泽湿地约从12 ka（1 ka=1000 cal.）开始发育,在距今8.6 ka以后开始广泛形成,约有35%的沼泽湿地形成于全新世暖湿期（8.0-4.0 ka）;而沼泽湿地发育的高峰期则集中在全新世晚期.这种发育趋势与全球北方主要区域沼泽湿地大规模发育趋势显著不同.古气候重建表明,全新世早期东北地区气候温暖湿润,处在有利于沼泽发育的时期,促进了沼泽湿地的形成;而在全新世晚期,东北地区呈现冷湿的气候组合特征,冷湿的气候条件不利于有机质的分解,进而促进了沼泽湿地的大规模形成和发育.此外,研究结果也表明全新世以来东北地区不同区域沼泽湿地发育的时间和规模呈现显著的空间差异,而温度和降水则是影响不同区域沼泽湿地发育的最重要因素.本研究将为我国东北地区沼泽湿地的保护和恢复提供一定的理论和数据支持.     

围压作用下岩石样品中微裂纹的闭合

岩石中普遍存在的微裂纹对其物理性质有十分显著的影响.为了得到不同围压条件下岩样内部微裂纹形态的变化,选取几种具有明显层理的岩石圈岩石样品,在不同围压下沿相互正交的三个方向对纵横波速度和线应变等进行了测量,根据O’Connell模型通过计算得出有效泊松比、裂纹密度、裂纹孔隙度和裂纹的c/a比值（a为硬币形裂纹半长轴的长度,c为其半宽度）.结果表明,随着围压的增加,在垂直于层理面的方向上裂纹闭合最快但c/a比值不减反增.结合显微组构分析可知,岩石中的裂纹表面实际上是凸凹不平的,在围压增加引起裂纹闭合过程中一条裂纹可以变成几个,长度成倍减小但宽度变化不大,所以在垂直于层理面的方向上c/a比值随围压增加而增大.但另两个方向上的变化明显不同,应该与模型本身的适用范围有关.通过同时测量纵、横波速度,计算c/a比值,可以对样品中微裂纹的几何形态及空间分布方式有定性或半定量的了解.     

THE DYNAMICS OF MAINTAINING THE TROPICAL CYCLONE 9012 AFTER ITS LANDING

Using 2.5 ×2.5 winds and pressure grid data, the angular momentum budgets are studied in this paper for TC 9012 (Yancy) which was kept active 65 hours after land fall.It is found that the inland TC 9012 moved into the center of a relatively stable saddle, in which large amount of humid air was entrained into the storm from the southerly jet at low level to bund up the energy of latent heat, the weak cold air coming from the north provided it with baroclinic energy, while the vorticity transfer of geostrophic angular momentum on the radius 4°-8°from the cyclone center at upper troposphere and the input of cyclonic angular momentum produced by the βterm are immediate factors maintaining the central pressure and maximum winds.