The Present Status and Prospect of Earthquake Focal Depth Locating

Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estimating aftershock evolutions and risk,as well as monitoring nuclear tests. However,how we determine an accurate focal depth is always a challenge in seismological studies. Aiming to solve these problems, we analyzed and summarized the present status and the future development of earthquake focal depth locating. In this paper we first reviewed the present status of focal depth locating in the world,and summarized the frequently-used relocating methods and ideas at present,and introduced two types of focal depth relocating ideas: arrival time relocating and waveform modeling methods. For these ideas,we systematically described the S-P and the Pn-Pg methods that belong to arrival time method,and polarization focal depth locating and amplitude focal depth locating that belongs to waveform modeling,and further analyzed the advantages and limitations of these methods. Since the depth phase methods are highly sensitive to focal depth,and are relatively free from the uncertainties of crustal models,we mainly reviewed the depth phases of s Pm P,s PL,s Pn,and s Sn,and quantitatively evaluated their availabilities and characteristics. Second,we also discussed the effects of crustal velocity models on the reliability of focal depth locating,and reviewed the advancements of seismic tomography techniques over recent years. Finally,based on the present status of the progress on the focal depth locating,and studies of seismic velocity structures,we proposed an idea of combining multiple datasets and relocating methods,jointly utilizing seismologic and geodetic techniques to relocate focal depth,which should be the major research field in investigating focal depth and source parameters in the near future.     

地磁总场测量阵列对磁性目标定位的方法

提出了用地磁总场对磁性目标定位的方法.以远场磁偶极子原理构建了地磁总场的测量阵列,设计了阵列对目标的定位算法,求解中采用二重梯度算法消除了地磁总场随时间变化和空间分布不均匀对目标定位的影响.实验验证了这种二重梯度算法的有效性.利用MATHCAD对定位算法中的非线性方程组进行了仿真,采用LINGO软件求解了阵列方程组.在松花江沿岸某地,用光泵磁传感器阵列对航行中的目标船进行了定位实验,所测磁场数据曲线与理论曲线完全吻合,证明了定位算法物理模型的正确性.提出了改进的磁场梯度偏置定位算法,进一步提高了目标定位精度.实验证明了这种地磁总场目标定位方法的可行性.     

基于时空局域化dreamlet单程波算子的观测系统沉降法偏移

Dreamlet偏移成像目的是探索一类能够对地震波场和单程波传播算子同时分解和压缩的理论和方法,也即实现在压缩域的传播与成像、地震数据在时间和空间的非平稳性质,决定了要实现地震数据的有效稀疏表示,分解方法必须在时间和空间上同时具有局域化性质.Dreamlet由时间和空间局部分解原子的张量积构成,可以看作一种脉冲-小波束形式的波场分解原子.时空局域化的dreamlet单程波传播算子在对波场沿深度方向延拓时,地震数据在时间轴上总是向同一方向流动.随着深度的增加,部分用于成像浅层结构的数据归位至其空间位置后被dreamlet算子丢弃,波场的有效记录时间变短,每一步用于波场延拓的计算量也相应下降.为了充分发挥这一优势,本文介绍dreamlet传播算子与观测系统沉降法偏移相结合的理论与方法.观测系统沉降法偏移每一步都将记录到的所有数据向下延拓,沉降后的波场等效于把源和检波器都放置在目标深度所能接收的反射数据.Dreamlet观测系统沉降过程只保留用于成像观测系统下部地质结构的有效数据,自动丢弃已经用于成像观测系统上部而对下部成像没有贡献的信号.本文通过二维SEG/EAGE叠后和Marmousi叠前数据算例展示了dreamlet传播算子应用于观测系统沉降法偏移的这一特点.数值算例结果显示,在不影响成像质量的前提下,该偏移方法能够有效减少传播数据量,为发展一种快速高效的偏移方法提供了新的思路.     

渤海常见土类剪切波速与埋深关系分析

土层的剪切波速是岩土地震工程中重要的物理量,本文利用多年来在渤海海域地震安全性评价中积累的资料,研究了渤海常见土类剪切波速和埋深的关系。利用非线性最小二乘法,采用指数函数、一次函数、二次函数、幂函数、"幂函数+常数函数"、"幂函数+一次函数" 6种回归模型对各类土的剪切波速和埋深的关系进行了回归分析,以拟合优度以及最小二乘拟合的误差平方和为评价指标对比了各种模型拟合效果的优劣。结果表明,"幂函数+一次函数"回归模型的拟合效果最好。此外,本文给出了该海域常见的7类土在此回归模型下的拟合公式的系数,以供工程中参考。     

华北典型污染地区多轴差分吸收光谱技术的气溶胶反演研究

基于华北典型污染地区的地基多轴差分吸收光谱仪（MAX-DOAS）近4年的观测数据,利用最优估计算法和LIDORT辐射传输模式反演了该区域气溶胶的消光系数垂直廓线和光学厚度（AOD）.MAX-DOAS观测反演的AOD与全球气溶胶观测网络同波段在华北地区的AOD间具有很好的一致性,相关系数都在0.9以上,证明MAX-DOAS具备对华北污染区域气溶胶光学厚度和消光系数垂直廓线的反演能力.AOD的反演误差表现为冬季最大,春夏最小,早晚大于正午,这是因为冬季以及早晚太阳天顶角较大导致信噪比偏小,所以AOD反演误差偏大.反演廓线表明该区域气溶胶主要集中在1 km以下的边界层,浓度随高度呈指数递减,部分情况下峰值出现在300 m处;气溶胶光学厚度夏季最大,冬季最小,正午较大,早晚较小.在东风条件下浓度最高,表明东边（即重工业城市唐山方向）的输送对香河和周边区域的气溶胶积聚有重要贡献.     

Spatial variability of E. coli in an urban salt-wedge estuary

This study investigated the spatial variability of a common faecal indicator organism, Escherichia coli, in an urban salt-wedge estuary in Melbourne, Australia. Data were collected through comprehensive depth profiling in the water column at four sites and included measurements of temperature, salinity, pH, dissolved oxygen, turbidity, and E. coli concentrations. Vertical variability of E. coli was closely related to the salt-wedge dynamics; in the presence of a salt-wedge, there was a significant decrease in E. coli concentrations with depth. Transverse variability was low and was most likely dwarfed by the analytical uncertainties of E. coli measurements. Longitudinal variability was also low, potentially reflecting minimal die-off, settling, and additional inputs entering along the estuary. These results were supported by a simple mixing model that predicted E. coli concentrations based on salinity measurements. Additionally, an assessment of a sentinel monitoring station suggested routine monitoring locations may produce conservative estimates of E. coli concentrations in stratified estuaries.     

耦合气溶胶气候模式FGOALS-f3-L模拟青藏高原地区气溶胶特性

基于新耦合气溶胶气候模式FGOALS-f3-L模拟分析了2002-2011年青藏高原地区气溶胶时空分布特征.结果表明:青藏高原地区,沙尘,硫酸盐,碳质气溶胶(包括黑碳,有机碳和混合碳)地表质量浓度分别占比为53.6％,32.2％,14.2％;在拉萨站点,模拟的气溶胶地表质量浓度被低估,尤其是黑碳和有机碳气溶胶;模拟的气...     

Mineralogical evidence for multiple dust sources in an early Triassic loessite

Loessite present in a borehole into the Smith Bank Formation (early Triassic age, Central North Sea) differentiates five coeval source terranes for aerosol dust, three long-distance sources and two local sources. All were active immediately following the end Permian mass extinction. Long-distance sources are sedimentary, basic magmatic and acid–intermediate volcanic. Although predominantly silt-sized and dominated by quartz with subordinate feldspars, muscovite and illite, evidence of basic and acid–intermediate magmatic/volcanic sources are pervasive. Baddeleyite is diagnostic of basic magmatism, an origin supported by enrichment of plagioclase relative to potassium feldspar. Deduction of acid–intermediate volcanism comes from the collective occurrence of irregular geometry quartz, volcanic shards, Ti-mineralization, euhedral biotite, sanidine, the co-occurrence of apatite and zircon, and the common occurrence of a tosuditic clay mineral. The tosuditic phase occurs as an unusual diagenetic dioctahedral chlorite/smectite formed at low temperature (<45°C), during very shallow burial by the decomposition of unstable rhyo-dacitic and andesitic grains in alkaline pore water from an adjacent lake that yielded pore fluids with a high Al : Si ratio. The Siberian Traps large igneous province is the likely source terrane for the magmatic and volcanic silt. Locally sourced clay pellets and kaolinite booklets formed from aeolian erosion of an adjacent, periodically desiccated lake-floor and a kaolinitic regolith, respectively. Inference of a prolonged harsh, arid climate leaves no evidence of any periods of sustained humidity or climatic fluctuation, such as pedogenesis. The association between the end Permian mass extinction, emplacement and aeolian erosion of the Siberian Traps large igneous province, and location of the Smith Bank Formation in a large lacustrine endorheic basin, combine to preserve a record of prolonged harsh climate in the early Triassic.     

南京市气溶胶PM2.5一次来源解析

在南京大学鼓楼校区（市区）和南京信息工程大学（郊区）校园,分季采集PM2.5及其主要排放源的颗粒样品,在南京大学现代分析测试中心用X-荧光分析法分析样品中的化学元素,应用化学元素平衡法（CMB）计算了各主要源对PM2.5的贡献。结果表明对市区扬尘和建筑尘是PM2．5最主要的贡献源,贡献率合计约70％;燃煤尘和冶炼尘仅为约15％。对郊区扬尘和煤烟尘是PM2．5的最主要贡献源,平均贡献率分别为50％和22．4％,建筑尘的平均贡献率为8．3％,冶炼尘的贡献小于8％。这些结果可为治理气溶胶细颗粒源提供决策依据。     

平流层臭氧对人类活动排放氯化物及氮氧化物的非线性响应

利用本文所建立的平流层下部臭氧异相光化学系统,研究硫酸气溶胶表面积浓度以及氯化物和氮氧化物的排放强度对系统状态的影响.光化系统由19种分别来自氧族、氢族、氮族、氯族和碳族的化学成分组成.研究结果指出,仅就气溶胶而言,它不是一个重要的决定光化系统行为的因子.然而,当它与奇氯ClOx或奇氮NOx的外源共同影响系统时,通过复杂的非线性光化学过程,它将使系统的行为发生重大变化.可以看到,在某些确定的参数范围内,系统存在多平衡态解,并构成一个“折叠"突变流型.