长岛震群b值随深度变化特征

利用双差定位方法对2017年2月~2018年5月长岛震群进行重定位, 根据重定位结果计算长岛震群地震集中活动区域b值在深度上的变化分布。 结果显示: 长岛震群重定位的结果主要表现为北、 南两个地震活动区域。 北部地震活动区域的地震数量多, 时间跨度长; 南部地震活动区域的地震数量较少, 形成时间较晚, 震源深度主要集中在地壳深度4~25 km之间; 长岛震群北、 南两个地震活动区域的b值总体上均随深度增大而减小, 在8.5 km深度左右均存在转折上升的情况。 长岛震群b值的深度变化特征表明, 其应力主要受围岩静压力影响, 受断裂活动影响较小。     

2015年7月3日新疆皮山MS6.5地震序列活动性及重新定位研究

2015年7月3日新疆皮山Mb>Sb>6.5地震发生在塔里木块体与西昆仑交会地区, 该地区近年来中强地震较为活跃。 本文对2015年新疆皮山Mb>Sb>6.5地震序列及其附近地区中强震序列b值等参数进行了研究。 另外, 还利用新疆台网的震相报告, 采用双差定位方法对余震进行了重新定位, 对皮山余震序列的主震破裂区地震活动时空变化特征进行了分析和讨论, 为该地区地震危险性评估提供参考。     

日本9.0级地震后依舒断裂带北段地震活动性分析

结合测震学和大地测量学方法分析日本2011年9级地震之后依舒断裂带北段的地震活动性认为,2012年至今研究区地震活动相对平静是由于日本地震对区域应力场的影响。依舒断裂带北段震后1 a内受影响较大,2 a后地震活动减弱,b值的时间扫描表现出其目前处于低应力场控制。依舒断裂带北段2012年至今5 a未发生4级以上地震,当前存在发生4级地震的可能。     

A high-resolution14C dated sediment sequence from southwest Sweden: age comparisons between different components of the sediment

A macrofossil-rich glaciomarine–marine–lacustrine sediment from a soft-water lake in southwestern Sweden has provided an opportunity to ¹⁴C date different components of its sediments. Bulk sediment dates are 100 to 500 yr older than fragile terrestrial macrofossils of corresponding levels, with a mean age difference of ca. 300 yr. This is explained by the presence of old and reworked organic material in the sediment. Five age comparisons between terrestrial macrofossils and periostraca of marine bivalves (probably Arctica islandica) of Allerød age give a mean age difference of 380 yr, i.e. slightly greater than the present reservoir age of 340 ± 30 yr for the Swedish west coast. This difference is roughly the same as for the marine macroalga Desmarestia aculeata. A date from shell carbonate fragments of Mytilus edulis yields an age that is more than 1000 yr older than corresponding periostraca and terrestrial macrofossils and 500–1000 yr older than the age of the supposed deglaciation of the site. Altogether this indicates a larger marine reservoir effect during the Allerød than at present. © 1998 John Wiley & Sons, Ltd.     

A mid-Oligocene cooling (Oi-2b) reflected in the dinoflagellate record and in depositional sequence architecture. An integrated study from the eastern North Sea Basin

Integrated micropaleontological (dinoflagellate and foraminifera) and 3D seismic studies of Oligocene surfaces were carried out in the eastern North Sea in order to investigate the influence of the climate on the evolution of depositional geometries and surface morphologies.     

东海原甲藻线粒体细胞色素b(Cytb)基因的定量检测

建立了检测东海原甲藻线粒体细胞色素b(Cytb)基因mRNA含量的实时荧光定量PCR方法.以甲藻Cytb基因的简并引物扩增得到984 bp长的东海原甲藻Cytb基因片段,经克隆、测序,制备并纯化质粒.以光度法测定质粒浓度并作为标准品.对上述基因片段,利用PRIMER EXPRESS 3.0 设计引物,以梯度稀释的质粒标准品进行定量PCR反应,以SYBR Green I为荧光染料,制作标准曲线,得到基因拷贝数X与Ct值的关系为:Ct=-3.50 lg X+39.35(相关系数r为0.999).通过对不同生长时期的东海原甲藻样品的Cytb基因mRNA含量检测,发现该基因的表达量较稳定,平均值为(45.4±4.7)拷贝/细胞,受生长状态影响不大,可作为实时荧光定量PCR的内参基因.     

The most resonant pulsation frequency of δ Scuti stars

Pulsation of the Sun with a period of Pb>0b> ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this Pb>0b> periodicity among other (short-period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency vb>0b> = Pb>0b>⁻¹ ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the Pb>0b> oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” Pb>0b> resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near-resonance with the “universal” vb>0b> frequency). The arguments are given favouring a cosmoogical nature of the Pb>0b> oscillation.     

The fractal geometry of the surface ruptures of the 1999 Chi-Chi earthquake, Taiwan

The 1999 September 20 Chi-Chi earthquake is the largest seismic event which occurred in the island during the twentieth century. Available seismic data relative to this earthquake are of high quality, and surface ruptures identified as features associated to the Chelungpu fault can be clearly observed at the surface and precisely mapped. We calculated the fractal dimension ( D ) and b value of Gutenberg–Richter law for 6-month aftershocks of the Chi-Chi earthquake for the fault area, and find that the surface ruptures exhibit self-similar geometry only within specific ruler intervals. The D values of the surface ruptures reflect the fault slip and geometry at depth. More importantly, the small-size aftershocks seem more likely to occur within high D value and high b value areas, whereas small D value and small b value areas have a high potential for medium- and large-size aftershocks.