川滇交界地区构造应力场及强震趋势的统计预测

本文对川滇地区中、强震震源机制解和中小地震平均节面解分析，指出川滇地区现今构造应力场在北西－北西西向压应力作用下，以水平剪切错动为主。同时，采用极值理论、最大信息熵、线性预测和灰色理论等方法综合分析，预测川滇地区未来强震的趋势。     

太湖缓冲带林下草坪的生长趋势研究

为提升太湖缓冲带林带的生态功能,减少入湖污染负荷,采用人工草坪替代林下杂草的方式,建立林草复合带.选取白三叶(Trifolium repens)、红花酢浆草(Oxalis corymbosa)、麦冬(Ophiopogon japonicus)、马蹄金(Dichondra erpens)和狗牙根(Cynodon dactylon)5种草坪,在典型缓冲带林地按间距25 cm统一移栽种植.采用定位监测的方法分析草坪的生长特征与发展趋势.结果表明:2011-2014年期间,除狗牙根无法形成稳定的种群被杂草取代外,其他4种草坪均能正常生长,并形成优势种群;4种草坪中,以麦冬和马蹄金生长状况最好,生物量、盖度、均一性和青绿期综合指标等级较高,其次是白三叶;红花酢浆草种群不稳定,受水热的影响大.     

Spatial distribution and temporal variation of reference evapotranspiration in arid and semi‐arid regions of Iran

Analysis of spatial and temporal variations of reference evapotranspiration (ET_o) is important in arid and semi‐arid regions where water resources are limited. The main aim of this study was to analyse the spatial distribution and the annual, seasonal and monthly trends of the Penman–Monteith ET_o for 21 stations in the arid and semi‐arid regions of Iran. Three statistical tests the Mann‐Kendall, Sen's slope estimator and linear regression were used for the analysis. The analysis revealed that ET_o increased from January to July and deceased from July to December at almost all stations. Additionally, higher annual ET_o values were found in the southeast of the study region and lower values in the northwest of the region. Although the results showed both positive and negative trends in annual ET_o series, ET_o generally increased, significantly so in six (～30%) of the stations. Analysis of the impacts of meteorological variables on the temporal trends of ET_o indicated that the increasing trend of ET_o was most likely due to a significant increase in minimum air temperature, while decreasing trend of ET_o was mainly caused by a significant decrease in wind speed. At the sites where increasing ET_o trends were statistically significant, the rate of increase varied from (+)8·36 mm/year at Mashhad station to (+)31·68 mm/year at Iranshahr station. On average, an increasing trend of (+)4·42 mm/year was obtained for the whole study area during the last four decades. Seasonal and monthly ET_o have also tended to increase at the majority of the stations. The greatest numbers of significant trends were observed in winter on the seasonal time‐scale and in September on the monthly time‐scale. Copyright © 2011 John Wiley & Sons, Ltd.     

中国大陆地震趋势分析

在近年全国地震大形势研究的基础上。根据中国大陆地震活动的时空强演化图像及其相关参数的统计结果,并结合大陆周围附近地区强震活动对其内部的影响等客观现象,对大陆地震活动趋势进行了研究预测。结果认为,中国大陆第五地震活跃期到2001年已经结束,2008年3月21日新疆于田7．3级地震可能是中国大陆新的地震活跃期开始。     

Temporal trend, spatial distribution, and terrestrial sources of PBDEs and PCBs in Masan Bay, Korea

Congener specific determination of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) was carried out in 21 surface sediment samples and a sediment core from Masan Bay, Korea. Among the 40 PBDE congeners targeted only 29 were detectable. PBDE congener profile within sediments was dominated by BDE-209 followed by BDEs-99, -47, -153 and -183, sequentially. In surface sediments, the average ΣPBDEs levels approached that of average ΣPCBs values. However, trends observed in the sediment core suggest that this pattern will alter over time and result in higher surface sediment PBDE concentrations than PCBs in future. Various diffuse and point sources for PBDEs and PCBs were identified in this location. Shipping and other industrial activities were associated with PCB contamination while domestic and industrial waste discharges corresponded with PBDE contamination. The average concentration for PBDEs and PCBs in surface sediments were 5.7, 7.2 ng/g dry weight, respectively.     

1950s以来鄱阳湖流域降水变化趋势及其持续性特征

以鄱阳湖流域1950s至2005年10个台站的日降水量为基础,采用距平分析、Mann-Kendall非参数检验对鄱阳湖流域1950s以来的年、季降水特征和变化趋势进行分析,并以此为基础,结合Hurat指数,从3年、5年、10年三个时间尺度上分析该流域未来降水的变化趋势.结果表明,鄱阳湖流域年内降水分配不均,年际变化较为...     

Mineral variation in anorthositic, troctolitic, and adamellitic rocks of the Barth Island layered structure in the Nain anorthosite complex, Labrador

The Barth Island layered structure is an oval, 6 by 9 km body, consisting of rhythmically layered adamellitic rock in the center which grades outward through jotunite into troctolite. Farther outward the sequence repeats itself in reversed order, strongly reduced in magnitude and finer grained; the adamellitic zone is followed by jotunite which grades into coarse-grained leuconorite and into anorthosite of the Nain complex. The Barth Island structure, having an inverted conical base topped by a hemispherical depression, seems to represent a distorted sequence of rock layers with troctolite at the bottom, grading upward into adamellitic rocks which grade into anorthosite at the top. Trend-surface analysis demonstrates the regional variation of plagioclase and orthopyroxene compositions in the troctolite—adamellite sequence of the central part of the structure. The fits for the second- and third-degree surfaces are good and significant at the 99 percent level. The regression line for compositional variation in coexisting plagioclase and orthopyroxene in all analyzed rocks has a correlation coefficient of r² = 0.78. The difference between the trends in the troctolite—adamellite sequence and the anorthosite—adamellite sequence is insignificant. The regression curve for compositional variation in coexisting orthopyroxene and olivine has a correlation coefficient of r² = 0.98. The curve shows good correlation with the experimentally established partitioning curve of Medaris, which indicates that equilibrium conditions prevailed during formation of the olivine—ortho-pyroxene pairs. The results suggest that the troctolite—adamellite sequence and the anorthosite—adamellite sequence are products of fractional crystallization, possibly from the same parental magma.     

Temporal evolution of the focal mechanism consistency of the 2021 Yangbi MS 6.4 earthquake sequence in Yunnan

Using the Cut And Paste (CAP) method, we invert the focal mechanism of 38 moderate earthquakes (M_S ≥ 3.0) recorded by Yunnan seismic network and analyze the corresponding focal mechanism consistency based on the minimum spatial rotation angle. Our results indicate that the M_S 6.4 mainshock is induced by a lateral strike slip fault (with a rake angle of ～ ?165°) and a little normal-faulting component event along a nearly vertical plane (dipping angle～ 79° and strike ～138°). Combining our results with high resolution catalog, we argue that the seismogenic fault of this earthquake sequence is a secondary fault western to the major Weixi-Qiaohou-Weishan fault. The focal mechanism evolution can be divided into three periods. During the first period, the foreshock sequence, the focal mechanism consistency is the highest (KA<36°); during the second period which is shortly after the mainshock, the focal mechanism shows strong variation with KA ranging from 8° to 110°; during the third period, the seismicity becomes weak and the focal mechanism of the earthquakes becomes more consistent than the second period (18°<KA<73°). We suggest that the KA, to some extent, represents the coherence between local tectonic stress regime and the stress state of each individual earthquake. Furthermore, high focal mechanism consistency and high linearity of seismic distribution may serve as indicators for the identification of foreshock sequence.     

对新疆乌恰—喀什地区年度地震预测的总结与思考

在对新疆1973年以来年度地震预测情况进行综合研究基础上,重点分析了乌恰-喀什周围地区年度预测的阶段性特点,并对这一地区1900年以来M≥6地震和1972-2008年M≥5.5地震活动特征进行了的研究.认为对该区域地震活动规律性特点认识不足,没有遵循本地区地震活动的基本规律对地震趋势进行客观判断,是造成地震危险区预测效果较差的主要原因.依据地震活跃与间歇的特点认为2008年底开始乌恰-喀什周围地区将进入一个新的活跃时段,这一地区可能仍将继续被划定为年度强地震危险区.