1518年6月22日韩国首尔以西海域——南黄海大震

1518年6月22日韩国首尔以西海域——南黄海发生大震。地震波及朝鲜半岛全境,并在韩国首尔等沿海地区造成破坏,首尔的烈度为Ⅷ度,余震持续一个多月。地震还影响到中国东部地区。震级定为M7?级。此次地震可能与朝鲜半岛西缘断裂带（南黄海东缘断裂带）的活动有关。震中定于该断裂带附近（36.5°N,125.2°E）。     

Aerosol properties over an urban site in central East China derived from ground sun-photometer measurements

Sun-photometer measurements at Hefei, an urban site located in central East China, were examined to investigate the variations of aerosol loading and optical properties. It is found that aerosol optical thickness (AOT) keeps higher in winter/spring and gets relatively lower in summer/autumn. The large AOT in winter is caused by anthropogenic sulfate/nitrate aerosols, while in spring dust particles elevate the background aerosol loading and the excessive fine-mode particles eventually lead to severe pollution. There is a dramatic decline of AOT during summer, with monthly averaged AOT reaching the maximum in June and soon the minimum in August. Meanwhile, aerosol size decreases consistently and single scattering albedo (SSA) reaches its minimum in July. During summertime large-sized particles play a key role to change the air from clean to mild-pollution situation, while the presence of massive small-sized particles makes the air being even more polluted. These complicated summer patterns are possibly related to the three key processes that are active in the high temperature/humidity environment concentrating on sulfate/nitrate aerosols, i.e., gas-to-particle transformation, hygroscopic growth, and wet scavenging. Regardless of season, the increase of SSA with increasing AOT occurs across the visible and near-infrared bands, suggesting the dominant negative/cooling effect with the elevated aerosol loading. The SSA spectra under varying AOT monotonically decrease with wavelength. The relatively large slope arises in summer, reinforcing the dominance of sulfate/nitrate aerosols that induce severe pollution in summer season around this city.     

川西高温水热活动区深部热结构的地球物理分析

川西高温水热活动区是地热学研究的典型地区之一,该区温泉、热泉点分布广泛,这些温泉大多沿北西-南东向的金沙江断裂、德格-乡城断裂、甘孜-理塘断裂、鲜水河三条主断裂呈条带状分布.对此高温水热活动区开展地热学分析,是研究青藏高原"东构造结"深部地球动力学过程、开发利用川西高原地热资源的重要基础,具有重要的科学研究意义和实际应用价值.本文针对实测氦同位素所发现的壳幔热结构比,依据重力、航空磁法、地震资料,采用反演莫霍面、居里面深度等方法,对川西高温水热活动区的深部热结构进行了分析.同时对中高温热泉密集出露的巴塘、理塘以及康定水热活动区的典型壳幔热流构与深部背景场进行了对比研究.结果表明,地表氦同位素热流估算的深部热流结构与地球物理异常结果保持较好的对应关系.川西地区热流结构中地壳、地幔的热贡献比较接近：巴塘地区平均Q_c/Q=51.38%、理塘地区平均Q_c/Q=54.39%、康定地区平均Q_c/Q=42.42%.川西地区表现出了"温壳温幔"型的深部热结构,但温地壳背景下形成较高地表热流的原因有待进一步研究.     

基于浅层反射地震勘探技术的大庆地区近地表构造特征研究

目前,对于大庆地区的地质构造研究成果仅局限在深部构造上,该地区从未开展过针对近地表隐伏断裂的探查工作.本文采用浅层反射地震勘探方法,查明了克山—大安断裂嫩江组以上地层的详细地层信息以及断裂的展布形态;同时,在主干断裂上覆的背斜构造中,发现了许多次级断裂,这些次级断裂在前人的成果中并未提出过,并且在本区的断裂-褶皱构造体系中,次级断裂的活动特性同样受主干断裂活动的影响;然后通过钻孔验证,证实了浅层反射地震勘探结果的可靠性,并且确定了次级断裂的最新活动时代;最后综合编制了松辽盆地长垣隆起地区浅层地质模型,并讨论了本地区的构造体系受晚白垩纪以来太平洋板块俯冲方向变化的影响而形成的构造特征.本次研究中的方法和成果可为大庆市城市发展规划、重大工程建设选址和大庆油田安全高效生产等提供科学依据,可为其他地区开展近地表断裂探查提供借鉴和参考,为本地区浅层地质构造后续研究提供了基础资料,填补该地区近地表地球物理勘探构造研究的空白.     

基于稀疏表示的地面磁共振信号提取方法

在多孔隙含水层中地面磁共振（surface nuclear magnetic resonance,SNMR）信号呈现多弛豫衰减特性,常规盲源分离方法和单指数拟合方法引起信号严重失真和信息缺失等问题.本文提出了基于稀疏表示的随机噪声背景下多弛豫SNMR信号的提取方法.根据SNMR信号的衰减特征,设计了精确刻画SNMR信号且与随机噪声不相关的离散衰减余弦冗余字典.其次,针对多弛豫SNMR信号稀疏度未知的问题,通过设置合理的残差比阈值控制迭代次数,改进了广义正交匹配追踪（generalized orthogonal matching pursuit,gOMP）算法,使得该方法应用于SNMR信号的提取时,具有更好的自适应性和普适性.再次,鉴于SNMR测量数据为多次独立重复采集的结果,提出了基于数据流的SNMR信号提取策略,在提高算法鲁棒性的同时,保证了信号提取结果的唯一性.最后,通过仿真和实测数据证明了基于gOMP算法的稀疏表示方法可以显著地提升多弛豫SNMR信号的提取质量,降低随机噪声对含水层反演结果的影响,提高SNMR探测能力.     

The Study on Seismicity and Relocation of the July 3,2015 Pishan MS6.5 Earthquake

The July 3, 2015 Pishan M_S6.5 earthquake occurred in the intersection area of the Tarim block and West Kunlun block where the moderate-strong earthquakes have become active in recent years. This paper has studied the seismicity parameters of the earthquake sequences such as the b-value in the Pishan region and its vicinity. In addition, we also relocated the aftershocks of the Pishan M_S6.5 earthquake using the seismic phase report by the double-difference method. The temporal and spatial variation characteristics of the Pishan earthquake sequence in the rupture zone are analyzed. The study is of great significance in the seismic hazard assessment in this region.     

日侧极光弧的发光强度与沉降电子能谱的相关关系

本文利用中国北极黄河站多波段全天空极光观测数据,选取稳定的日侧极光弧,统计研究了极光强度比I_(557.7)/I_(630.0)与极光发光强度I_(557.7)的相关关系.发现I_(557.7)在午前暖点和午后热点区附近出现极大值,分别为2.2kR和2.9 kR;而I_(630.0)在磁正午出现极大值,为1.5kR.当I_(557.7)从0.1kR增加到10kR时,极光强度比I_(557.7)/I_(630.0)也由0.2增加到9.结合DMSP卫星探测的沉降粒子能谱数据,找到17个DMSP卫星穿越黄河站上空极光弧的事件,共穿越40条极光弧.得到了沉降电子的平均能量正比于极光强度比I_(557.7)/I_(630.0),沉降电子的总能通量正相关于极光强度I_(557.7)的关系式.利用该关系式反演所有极光弧的电子能谱,发现在午前和午后扇区,产生极光弧的沉降电子主要来源于等离子体片边界层;在高纬出现强度较弱的弧,对应等离子体幔区域.在磁正午附近,沉降电子的平均能量较低,极光弧处于低纬一侧,粒子源区主要是低纬边界层.     

强震记录对三个土层地震反应分析程序的检验

为了对国内外广泛使用的3个一维土层地震反应分析程序（DENSOR98、SHAKE91和LSSRLI-1）的计算精度进行检验,本文以4次地震中唐山响瞠井下三维台阵的基岩强震记录为输入地震动,利用这3个程序对此测井剖面分别进行计算,计算结果分别与同次地震中相应的台阵地表强震记录相比较,可得如下结论：在地震动不大的情况下,3个程序都可满足工程要求,其差别为SHAKE91算得的峰值偏大,DENSOR98算得的峰值偏小,LSSRLI-1得到的反应谱更接近实际,DENSOR98得到的反应谱偏低,从安全角度和经济角度综合来看,LSSRLI-1程序较好。     

Vertical variations and composition of dissolved free amino acid in the seawater of the Yap Trench in the western Pacific Ocean

The composition and concentration of dissolved free amino acid (DFAA) of seawater samples collected in May 2016 from the surface to the hadal zone of the northern region of the Yap Trench were analyzed by pre-column derivatization of o-phthalaldehyde. Results show that the average concentration of DFAA in the study area was 0.47±0.36 µmol/L. In different sampling stations, the concentrations of DFAA with water depth showed complex variation patterns. At the sediment-seawater interface, the concentrations of DFAA in the western side of the trench were obviously higher than that in its eastern side. In the study area, there were no significant correlations between the concentrations of DFAA and the environmental parameters such as concentrations of chlorophyll a (Chl a), dissolved oxygen (DO), pH, and dissolved inorganic nitrogen (DIN), indicating that the concentrations of DFAA in seawater of the trench are affected by many factors, such as photosynthesis, respiration, temperature, pressure, illumination, and circulation. The dominant DFAA are similar in different water layers of sampling stations, including aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), and serine (Ser). The composition of different amino acids, and the relative abundance of acidic, basic, and neutral amino acids might be related to the sources and consumption of various amino acids. Nine pairs of amino acids in the DFAA showed significantly positive relationship by correlation matrix analysis, suggesting that they might share similar biogeochemical processes. The degradation index (DI) of the DFAA in seawater of the Yap Trench could reflect the degradation, source, and freshness of DFAA in the trench to some extents. This is a preliminary study of amino acids from sea surface to hadal zone in the ocean, more works shall be done in different trenches to reveal their biogeochemical characteristics in extreme marine environments.

     

基于GIS分析的泰安市地质灾害风险评价

泰安市地处鲁中山区,山地丘陵广泛分布,崩塌、滑坡、泥石流和岩溶塌陷等地质灾害较为发育。本次研究依托新一轮1∶5万地质灾害风险普查,基于ArcGIS平台空间分析功能对高精度DEM、构造、工程地质和水文地质、降雨及植被等数据分析和提取,利用信息量法和层次分析法分别对崩滑泥石流和岩溶塌陷易发性评价,以降雨作为危险性评价因子,综合考虑人口和经济因素选择用地类型作为易损性条件进行风险区划,最终划分为地质灾害风险高、中、低3个等级,为今后有效开展自然灾害综合防治、衔接国土空间规划和保障经济社会可持续发展提供基础依据。