加卸载响应比的新进展

本文对此作简要介绍。主要有下三方面：①预测效果好：2004年发生在中国大陆有资料地区的ML≥15级地震共17次,其中15次落入用加卸载响应比方法于2003年底预测的区域内。②通过大量基础研究(包括数值模拟,岩石力学实验及统计细观损伤力学研究),使加卸载响应比理论(LURR)建立在一个比较牢靠的科学基础上。③LURR有很大的潜力和发展空间。未来的发展空间,除预测天然地震外,还可能对矿震、水库地震、滑坡等自然灾害,甚至其它自然系统以致社会系统的灾变作出预测。     

DLS型高精度多功能拾振器的设计与应用

文中介绍了新研制的便携式高精度多功能拾振器的技术性能、工作原理和理论计算,分析讨论了仪器的特点,给出了技术指标实测结果并进行了结构微振动记录幅值谱分析。     

高分辨率卫星影像图在震害快速预估中的应用

随着高分辨率卫星遥感技术的发展,遥感技术在地震灾害预估、评估和地震应急工作中发挥着越来越重要的作用,并成为震害评估和应急工作的重要发展方向之一。通过分析高分辨率遥感影像上建筑物的影像特征,设计了一种自动提取建筑物三维信息的模型;将提取出的建筑物三维信息,结合实验区人工调查的人口、经济数据．利用震害矩阵计算出不同类型建筑物在地震烈度场内的破坏等级和不同破坏等级建筑物的总面积,给出一定地震等级下的人员伤亡和经济损失的实际数据,建立了一套利用高分辨率卫星进行震害预估的技术流程。选取上海市宝山区为试验区．利用该技术进行了震害预估试验研究。预估结果具有较高的精度。     

Rocky desertification and its causes in karst areas: a case study in Yongshun County,Hunan Province,China

Rocky desertification, a process of land degradation characterized by soil erosion and bedrock exposure, is one of the most serious land degradation problems in karst areas, and is regarded as an obstacle to local sustainable development. It is well known that human activities can accelerate rocky desertification; however, the effects of climate change on rocky desertification in karst areas are still unclear. This study focused on the effects of temperature and precipitation changes and human activities on rocky desertification in karst areas to determine the impacts of climate change and human disturbances on rocky desertification. Areas of different level of rocky desertification were obtained from Landsat TM (1987) and Landsat ETM+ (2000) images. The results show that, although the total desertification area increased by only 1.27% between 1987 and 2000, 17.73% of the slightly desertified land had degraded to a moderate or intense level, 2.01 and 15.71%, respectively. Meanwhile, between 1987 and 2000, the air temperature increased by 0.7°C, and precipitation increased by 170 mm. Statistical results indicate that the increase in precipitation was caused by heavy rainfall. In addition, under the interactive influences of heavy rainfall and temperature, the average karst dissolution rate was about 87 m³ km⁻² a⁻¹ during the 14 years in the study area. Further analysis indicated that rocky desertification was positively related with the increase in temperature and precipitation and especially with the heavy rainfall events. Climate change accelerated rocky desertification in the karst areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

2001年1月26日高纬磁层顶通量管事件的观测研究

2001年1月26日11:10～11:40UT, ClusterⅡ卫星簇位于午后高纬磁鞘边界层和磁鞘区,此 时行星际磁场Bz为南向. 本文对在此期间观测到的多次磁通量管事件作了详细的研究 ,获得一系列的新发现：（1）高纬磁鞘边界层磁通量管的出现具有准周期性,周期约为78s ,比目前已知的磁层顶向阳面FTE的平均周期（8～11min）小得多. （2）这些通量管都具有 强的核心磁场;其主轴多数在磁场最小变化方向,少数在中间变化方向,有些无法用PAA判 定其方向（需要用电流管PAA确定）,这与卫星穿越通量管的相对路径有关. （3）每个事件 都存在很好的HT参考系,在HT参考系中这些通量管是准定常态结构;所有通量管都沿磁层顶 表面运动,速度方向大体相同,都来自晨侧下方. 通量管的径向尺度为1～2RE, 与通 常的FTE通量管相当. （4）起源于磁层的强能离子大体上沿着管轴方向由磁层向磁鞘运动; 起源于太阳风的热等离子体沿管轴向磁层传输. 通量管为太阳风等离子体向磁层输运和磁层 粒子向行星际空间逃逸提供了通道. （5）每个通量管事件都伴随有晨昏电场的反转,该电 场为对流电场.     

Least squares spectral analysis and its application to superconducting gravimeter data analysis

Detection of a periodic signal hidden in noise is the goal of Superconducting Gravimeter (SG) data analysis. Due to spikes, gaps, datum shrifts (offsets) and other disturbances, the traditional FFT method shows inherent limitations. Instead, the least squares spectral analysis (LSSA) has showed itself more suitable than Fourier analysis of gappy, unequally spaced and unequally weighted data series in a variety of applications in geodesy and geophysics. This paper reviews the principle of LSSA and gives a possible strategy for the analysis of time series obtained from the Canadian Superconducting Gravimeter Installation (CGSI), with gaps, offsets, unequal sampling decimation of the data and unequally weighted data points.     

叠前深度偏移技术在活动断层探测中的应用

通过叠前深度偏移与常规处理的方法原理对比及实例分析,说明叠前深度偏移技术利于求准速度的纵横向变化、利于提高复杂构造和小断层的成像清晰度和精度,该技术在精细速度分析、正确速度—深度模型建立和叠加方法上的优势,在浅层地震勘探中具有广泛的推广价值。文中叠前深度偏移技术在活动断层探测中的应用实例表明,叠前深度偏移剖面与常规处理剖面相比,具有如下特点：①归位准确、断点清楚;②分辨率和信噪比更高;③真实反映地下构造形态;④解决速度陷阱问题,直接、精确给出地质层位深度。     

20世纪后30年十堰市暴雨时空分布特征

根据20世纪后30年(1971～2000年)十堰市及其所属郧西、郧县、丹江口、竹溪、竹山、房县等6县(市)气象台站逐日降水资料,采用统计分析方法,对近30年该市暴雨、大暴雨与局部暴雨的时空分布特征作了探讨。结果表明：(1)十堰市暴雨、大暴雨及局部暴雨季节性特点明显,暴雨主要集中于6月下旬至8月上旬;(2)暴雨、大暴雨及局部暴雨的年代分布是中间多、两头少,呈现波浪型周期变化趋势;(3)暴雨存在一个西南-东北向雨带;(4)郧西和丹江口局部暴雨多,与秦岭山脉和大巴山脉东段间迎风面的地形抬升作用有关。     

Spectral lag of gamma‐ray bursts caused by the intrinsic spectral evolution and the curvature effect

Assuming an intrinsic ‘Band’ shape spectrum and an intrinsic energy‐independent emission profile we have investigated the connection between the evolution of the rest‐frame spectral parameters and the spectral lags measured in gamma‐ray burst (GRB) pulses by using a pulse model. We first focus our attention on the evolution of the peak energy, E_0,p, and neglect the effect of the curvature effect. It is found that the evolution of E_0,p alone can produce the observed lags. When E_0,p varies from hard to soft only the positive lags can be observed. The negative lags would occur in the case of E_0,p varying from soft to hard. When the evolution of E_0,p and the low‐energy spectral index α₀ varying from soft to hard then to soft we can find the aforesaid two sorts of lags. We then examine the combined case of the spectral evolution and the curvature effect of fireball and find the observed spectral lags would increase. A sample including 15 single pulses whose spectral evolution follows hard to soft has been investigated. All the lags of these pulses are positive, which is in good agreement with our theoretical predictions. Our analysis shows that only the intrinsic spectral evolution can produce the spectral lags and the observed lags should be contributed by the intrinsic spectral evolution and the curvature effect. But it is still unclear what cause the spectral evolution (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Experimental Study on Complete Consolidation Behavior of Hong Kong Marine Deposits

The time-dependent feature of soft soils has gained intensive attraction in recent years. Due to the high water content and viscous property, the Hong Kong marine deposit (HKMD) frequently poses a challenge to geotechnical practice, particularly to the reclamation in Hong Kong. A key issue related to reclamation design, foundation construction and maintenance is excess settlement/deformation of the ground. Formation of HKMD typically goes through sedimentation and self-weight consolidation. A series of one-dimensional settling column consolidation tests, together with conventional oedometer tests were conducted on the HKMD. By normalizing parameter in settling stage, a unique global relationship of effective stress, σ_z′ and strain, ?_z could be established. Results reveal that the settling curve and settling rate are significantly affected by the sediment concentration in self-weight consolidation. After the primary self-weight consolidation, the settling rate is reduced in the “secondary self-weight consolidation.”