2015年3月新不列颠MS7.4地震震源及邻区构造应力场特征

2015年3月30日至5月15日,巴布亚新几内亚-新不列颠地区发生了一系列地震.为研究该地区的构造应力环境及孕震背景,本文基于Global CMT目录,对新不列颠区域浅部进行构造应力场反演,拟得到高精度的应力图像.反演结果显示：（1）沿着南、北俾斯麦块体边界的区域构造应力场呈走滑体系,最大主压应力轴方位呈SWW-NEE向.（2）所罗门海的NW和NE走向的海沟处于压缩状态,所罗门海块体向新不列颠和所罗门群岛俯冲的板块弯曲部分是局部拉张.（3）受俯冲带的北向推挤,南俾斯麦板块顺时针旋转的挤压,太平洋板块向西部运动汇聚作用,新不列颠岛东北部与新爱尔兰岛南部交汇区域呈现明显非均匀应力状态.（4）此次地震序列的大多数走滑型和逆冲型地震,可能是所罗门海块体俯冲运动,和南俾斯麦块体与太平洋板块的近EW向挤压作用共同引发.

     

澜沧、耿马地震前的定点形变异常特征

本文分析了1988年11月6日云南澜沧、耿马地震前定点形变异常特征。趋势性异常主要表现为异常持续时间较短,变化迅速,倾斜方向一致。异常持续过程中出现1—2个加速变化阶段;短期异常出现在震前2—6个月,主要表现为倾斜矢量打结、方向改变及速度明显减小;形变异常的方向与震中方向有一定的联系。     

面波频散曲线快速追踪算法

层状地球模型面波频散理论传播矩阵法采用传统的Knopff's root-bracketing算法求频散函数的根即相速度,并广泛应用至今。本文提出了一个自动追踪求根算法,使频散曲线的计算变得更为有效,方便和快速。     

腾冲火山岩矿物化学研究

通过电子探针分析,系统研究了腾冲火山岩１０５个造岩矿物的化学成分。研究表明：本区熔岩中的橄榄石为贵橄榄石兼少量透铁橄榄石,斜方石为古铜辉石兼紫苏辉石,单斜辉石为普通辉石兼少量 质透石,斜长石为拉长石兼部分中长石和少量更长石,角闪石为低铁普通角闪石,黑云母为钛铁黑云母为钛铁黑云母为钛铁黑云母兼富铁黑云母。     

富蕴地震断裂带的若干定量特征

对富蕴地震断裂带９处不同地段的平板地质测量结果表明：北部引张段地震断裂 带宽约２２０ｍ,断坎平均高０．４ｍ;中部主体走滑段地震断层长达５３５ｍ以上,断层水平位移为１．８￣７．８ｍ断坎高０．４￣１．２ｍ,水平位移与垂直位移之比为５．７￣８．６;南部末端破裂段地震抛掷巨石距离达４０ｍ,地震断层水平位移为０．４￣９．９ｍ,断坎平均高０．２ｍ,末端及副断层水平位移与垂直位移之比高达２５￣２８。     

四川汶川8级大地震灾害损失快速评估研究

地震发生之后,在没有开展地震现场调查之前,迅速对地震造成的人员伤亡、直接经济损失等进行评估,对地震应急救援决策非常重要．本文叙述了基于宏观经济指标的地震灾害损失评估方法,根据我国1989——2004年地震现场灾害损失调查资料重新确定的地震易损性模型,给出了汶川8级大地震发生后依据估计的经验地震烈度图得到的地震损失快速评估结果,并与依据现场调查确定的地震烈度分布图给出的地震损失评估结果进行了比较．表明根据近20年我国实际地震震例确定的地震易损性模型具有较好的适用性,损失评估结果的最大不确定来自于对地震影响场的估计．     

2007年宁洱6.4级地震研究

根据云南宁洱地区地质构造、 历史强震资料、 云南监测中心区域台及现场流动台数字化观测台网测定的2007年宁洱6.4级地震序列资料及1970年以来宁洱地区6级地震序列等, 深入分析研究了宁洱地区中强地震活动规律、 宁洱6.4级地震的余震时空展布以及参数变化等特征, 并利用2007年宁洱6.4级地震地震现场数字化观测流动台测定的余震波资料研究了该序列地震波动力学特征。 研究结果认为, 宁洱6级地震活动在空间上具有较高的原地重复性, 在时间上具有强弱交替活动的韵律; 2007年6月3日宁洱6.4级地震的余震展布方向与穿过震区NW向宁洱断裂的走向大致一致, 宁洱6.4级地震可能是由无量山断裂活动构造加剧所引起;根据2007年6月3日宁洱6.4级地震序列及历次宁洱6级地震序列时序发展特征分析研究得出, 宁洱6.4级地震序列能量主要集中在震后3天内释放, 4.9级以上余震发生在主震当天, 地震序列早期参数和3.0级以上余震的垂直方向P波最大振幅与S波最大振幅非线性关系等显示, 宁洱6.4级地震序列具有较明显的主-余震型特征。     

Probabilistic spatial prediction of categorical data using elliptical copulas

This study uses elliptical copulas and transition probabilities for uncertainty modeling of categorical spatial data. It begins by discussing the expressions of the cumulative distribution function and probability density function of two major elliptical copulas: Gaussian copula and t copula. The basic form of spatial copula discriminant function is then derived based on Bayes’ theorem, which consists of three parts: the prior probability, the conditional marginal densities, and the conditional copula density. Finally, three kinds of parameter estimation methods are discussed, including maximum likelihood estimation, inference functions for margins and canonical maximum likelihood (CML). To avoid making assumptions on the form of marginal distributions, the CML approach is adopted in the real-world case study. Results show that the occurrence probability maps generated by these two elliptical copulas are similar to each other. However, the prediction map interpolated by Gaussian copula has a relatively higher classification accuracy than t copula.     

Evolution of the Southern Yellow Sea Cold Water Mass during the last 7 kyr from benthic foraminiferal evidence

The Southern Yellow Sea Cold Water Mass(YSCWM) is closely related to the modern circulation system of the east China shelf seas, which has significantly influenced regional marine environmental changes. The study of the Holocene evolution of the YSCWM will greatly improve our understanding of the mechanisms of regional environmental change. Benthic foraminifera are sensitive to bottom water environmental changes and can serve as useful indicators in bottom water environmental reconstruction. In this study, benthic foraminifera were analyzed in core N02 from the northwestern margin of the southern Yellow Sea Mud to decipher the phase evolution of the YSCWM during the last 7 kyr. Benthic foraminifera census counts and Q-mode factor analysis indicate that the Holocene sedimentary environment can be divided into three stages: From6.9–5.0 ka, the fauna was dominated by Ammonia ketienziensis, indicating that the YSCWM was at its strongest during the last 7 kyr, while the Yellow Sea Coastal Current(YSCC) had a weak influence on the bottom water of the study area. From 5.0–2.9 ka,the relative abundance of Hanzawaia nipponica remarkably increased while the abundance of A. ketienziensis decreased significantly, reflecting that the strength of the YSCWM was relatively weak and the range of the YSCWM might have contracted. The influence of the YSCC on the bottom water might have slightly increased, although its influence was still weak during this time. A notable increase in low-temperature and low-salinity species, such as Protelphidium tuberculatum and Buccella spp. has occurred since 2.9 ka, indicating that the YSCC has had a strong influence on bottom water during this period,while the strength of the YSCWM has been at its weakest during the last 7 kyr. Generally, the influence of the YSCWM and the YSCC on the bottom water properties of the study area show an obvious seesaw pattern, with one's influence increasing while the other's influence decreases and vice versa. The fluctuations in the strength of YSCWM during the Holocene may be caused by the different effect allocations of regional climatic factors(i.e. El Ni?o Southern Oscillation, East Asian Winter Monsoon,summer insolation in the northern hemisphere, etc.) acting on the circulation system during different periods.     

Changes in the plain river system and its hydrological characteristics under urbanization – case study of Suzhou City,China

ABSTRACT

Rapid urbanization in China has severely disturbed the underlying surface and river systems. The stream structure parameters of Suzhou City were analysed to study the evolution and spatial differentiation of a water system undergoing urbanization. The influencing pattern of different urbanization processes on river system structure and hydrological processes was detected by statistical methods and simulation analysis. The results show that urban sprawl is influenced by both the natural environment and the social economy. At different stages of urbanization, the spatial urban expansion and the natural river characteristics influence the evolution of the river network: during rapid urbanization, the decline in surface water ratio and river density is more intense. The decrease of surface water ratio and river density in rapidly urbanized areas was greatest, followed by that in area urbanized in the 1980s, with few changes in the old town. Under high urbanization, river system indicators tend to stabilize. The rivers’ hydrological features were affected by urbanization, with water yield in the study area increasing from 0.81 to 0.95 m³/m² (1991–2015). The same rainfall intensity results in higher flood levels and greater risk of flooding under rapid urbanization.