2014年云南景谷6.6级地震前后活动能量场分析

本文将地震释放能量作为地震活动场的基本要素, 采用自然正交函数展开方法, 系统研究2014年景谷6.6级地震震中区域地震活动能量场的时空特征。 结果表明, 景谷6.6级地震前能量场的前4个主要特征值对应的典型能量场时间因子都出现明显上升变或下降异常, 空间等值线形成局部能量高值异常危险区, 可能是景谷 6.6级地震空间异常的中短期特征。 我们还进一步研究了景谷6.6级地震前后空间异常随时间的演变, 给出了异常发展变化模式, 最后应用研究地震资料的累积次数从物理角度解释异常形成的机制。     

福建测震台网单台震级偏差与台站场地响应关系的初步分析

利用福建测震台网2008年10月~2015年12月记录的每个事件至少有6个台站测算震级的3069个区域地震事件,进行单台震级与台网平均震级的偏差统计,获得了各台站的总的震级平均偏差为-0.31~0.68,并统计各台站测算震级所量取最大记录振幅相应的周期,获得优势周期为0.06~0.38s;通过Moya方法反演各测震台站的场地响应,获得98个台站对1~20Hz频带的场地响应,结果显示场地对某些频带信息有放大或抑制作用;通过比较Wood-Anderson地震仪摆固有0.8s周期所对应的场地响应、各台样本优势周期所对应场地响应的震级偏差与各台总的震级平均偏差,发现台站测算震级相应优势周期的场地响应的震级偏差与台站震级平均偏差有较好的线性关系,表明单台震级的偏差与测算震级所量取最大记录振幅相应的周期的场地响应有较大关系。     

Analysis of the 2012–2013 Torreperogil-Sabiote seismic swarm

This study analyses the temporal clustering, spatial clustering, and statistics of the 2012–2013 Torreperogil-Sabiote (southern Spain) seismic swarm. During the swarm, more than 2200 events were located, mostly at depths of 2–5 km, with magnitude event up to m_bLg 3.9 (M_w 3.7). On the basis of daily activity rate, three main temporal phases are identified and analysed. The analysis combines different seismological relationships to improve our understanding of the physical processes related to the swarm's occurrence. Each temporal phase is characterized by its cumulative seismic moment. Using several different approaches, we estimate a catalog completeness magnitude of m_c≅ 1.5. The maximum likelihood b-value estimates for each swarm phase are 1.11 ± 0.09, 1.04 ± 0.04, and 0.90 ± 0.04, respectively. To test the hypothesis that a b-value decrease is a precursor to a large event, we study temporal variations in b-value using overlapping moving windows. A relationship can be inferred between change in b-value and the regime style of the rupture. b-values are indicators of the stress regime, and influence the size of ruptures. The fractal dimension D₂ is used to perform spatial analysis. Cumulative gamma and beta functions are used to analyse the behaviour of inter-event distances during the earthquake sequence.     

港珠澳跨海工程沉管隧道三维地震反应分析

以港珠澳大桥沉管隧道为工程研究背景,考虑管节接头GINA止水带的橡胶材料特性、场地的初始地应力平衡以及上覆动水压力作用等,分析了水平及竖向地震作用下沉管隧道三维动力反应。结果表明:动水压力对隧道结构的竖向及水平方向的动力响应均有一定影响,尤其是对隧道结构的竖向反应影响较水平方向更加明显,最大可达70%;隧道接头GINA止水带竖向剪切变形较水平纵向的拉伸变形及水平横向剪切变形明显偏大,尤其两侧止水带竖向剪切变形较大;混凝土隧道管节上顶板及边墙较管节底部更易受到明显的拉应力。     

Crustal attenuation characteristics of S-waves beneath the Eastern Tohoku region,Japan

An inversion method was applied to crustal earthquakes dataset to find S-wave attenuation characteristics beneath the Eastern Tohoku region of Japan.Accelerograms from 85 shallow crustal earthquakes up to25 km depth and magnitude range between 3.5 and 5.5were analyzed to estimate the seismic quality factor Q_s. A homogeneous attenuation model Q_s for the wave propagation path was evaluated from spectral amplitudes, at 24 different frequencies between 0.5 and 20 Hz by using generalized inversion technique. To do this, non-parametric attenuation functions were calculated to observe spectral amplitude decay with hypocentral distance. Then, these functions were parameterized to estimate Q_s. It was found that in Eastern Tohoku region, the Q_s frequency dependence can be approximated with the function 33 f~(1.22) within a frequency range between 0.5 and 20 Hz. However,the frequency dependence of Q_s in the frequency range between 0.5 and 6 Hz is best approximated by Q_s(f) = 36f~(0.94) showing relatively weaker frequency dependence as compared to the relation Q_s(f) = 6 f~(2.09) for the frequency range between 6 and 15 Hz. These results could be used to estimate source and site parameters for seismic hazard assessment in the region.     

震前蒙城地震台地脉动噪声的特征

对本台数字化地震观测以来记录到的典型地震,运用数字地震信号处理方法,测算每个抽选地震震前一分钟地脉动信号在时间域和频率域的特征数据,通过频谱分析法,获得了震前地脉动噪声频谱的差异性。初步研究了典型地震震前地脉动频谱变化的特征和规律,共归纳了18类震前地脉动噪声类型,按照无震平静分钟值脉动频谱特征类比典型地震震前分钟值频谱的异样变化,发现正常与异常的地脉动噪声特征,最主要的还是受震级强度和地理位置的影响较大。临震前地脉动分钟值频谱特征异常,可用于震前脉动前兆异常变化跟踪,从而利用地脉动频谱的特征参量监测地震孕育过程,为地震中长期及短临预报提供依据。     

开采上保护层对巨厚砾岩诱发冲击矿压的减冲机制分析

为研究开采上保护层对巨厚砾岩断裂诱发冲击的防治作用,根据跃进煤矿25采区的地质条件和采掘条件,将25110工作面下巷作为研究对象,从理论上分析了动静载叠加诱发冲击矿压的机制以及开采上保护层后的防冲原理,数值模拟研究了未开采上保护时和开采上保护层后在同等强度的动载扰动应力的影响下巷道底板的位移、速度、应力以及塑性区的变化规律,进行相似模拟试验研究了人工震源的作用下未开采上保护时和开采上保护层后巷道底板的加速度和动应力响应规律。结果表明,上保护层开采后能够有效地释放围岩内部的高应力,且采空区顶板自然垮落,形成的软弱松散岩层结构,能够更好地起到对动载扰动应力波的衰减作用,从而降低了冲击矿压发生的可能,一定程度上能够较好地防治冲击矿压。研究成果对巨厚砾岩下冲击矿压的防治具有一定指导意义。     

应用质量通量评估地下水中BTEX和乙醇的自然衰减

近年来,应用于修复石油烃污染地下水的监测自然衰减技术得到了广泛深入研究,同时质量通量方法已逐渐成为评 估地下水燃油污染场地自然衰减监测修复效能的重要手段。通过在室内砂槽中添加乙醇汽油组分,监测其自然衰减,利用 质量通量方法,得出了BTEX和乙醇的质量减少率、自然衰减速率常数K;结合非反应示踪剂溴离子,评价了BTEX和乙醇 自然衰减因素中吸附和微生物的联合降解效应。结果表明,自然衰减是地下水中燃油组分修复的重要机制,质量通量方法 是评估自然衰减的有效方法之一。BTEX和乙醇在自然衰减过程中被去除的比例分别为78.88%和98.71%,其中约98%的 BTEX 因吸附和生物降解联合作用被去除,接近100%的乙醇因内在生物降解作用被去除;BTEX 的自然衰减速率为 0.077d-1~0.167d-1,乙醇为0.353d-1,自然条件下乙醇比BTEX更容易衰减。     

The Enya mounds: a lost mound-drift competition

The genesis and evolution of cold-water coral banks along the Northeastern Atlantic margin is known to be influenced by several factors, among which the palaeotopography and nature of the coral settling surface, the presence of bottom currents and sediment supply. In this paper, a case study is presented of the Enya mound cluster, located in the southernmost tip of the Belgica mound province, west of Ireland. Below this mound cluster, seismic stratigraphy revealed a yet unmapped local unconformity RD1b, being part of a composite erosion event (RD1). As such, from the Late Miocene to Late Pliocene, at least two erosional events have incised the margin, ending with the final RD1a “moundbase” unconformity, acting as a base for the Enya mounds. During the Quaternary the mounds became outgrown and were covered by a mounded contourite drift. In addition, they are closely associated with a cluster of seabed pockmarks. The bottom current regime which became active since the Middle Pleistocene has certainly influenced the fate of this mound cluster. The occurrence of the pockmarks seems to be related to relatively recent fluid migration processes, however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks.     

地图综合中的地图目标自相似性分形衰减研究

分形衰减是指在地图综合中,地图目标随着比例尺的变化其结构形态随之发生改变,其自相似程度是递减变化的,反应到分维数的变化上,称之为分形衰减。本文以分形分析方法作为工具,分维值作为度量参数,分析地图综合中地图目标的分形衰减现象。以扩展分维作为理论基础,从变维分析的角度出发,研究地图目标的自相似程度随比例尺变化而衰减的规律,进一步研究地图目标的尺度指标与分形衰减之间的关系。