The solar and lunar effect of earthquake duration and distribution     

Zhenxia Zhang  Shugui Wu  Jianyong Li 《地震科学（英文版）》2013,26(2):117-124

Phase folding algorithms are conventionally used in periodicity analyses using X-ray astronomy pulsar. These allow for accurate identification of the cycle and phase characteristics of the physical parameters of the periodic variation. Although periodic variations in earthquake activity have long been studied, this paper is the first to apply the phase folding algorithm to the analysis of shallow (<70 km) seismic data for the period 1973–2010. The goal is to study the phase distribution characteristics of earthquake frequencies and we see a connection between earthquake occurrence and solar and lunar cycles. First, the rotation of the Sun may play a significant role in impacting on the occurrence time of earthquakes with magnitudes of less than 6.0. This may be especially pertinent for earthquakes with magnitudes between 5.0 and 6.0, when the modulation ratio reaches 12 %. The Moon’s gravity, which is generally thought to have the greatest influence on the global environment, may actually play less of a role on earthquake timing than the rotation of the Sun. Second, when we consider the world to be divided into 72 local regions based on latitude and longitude, we can see that there are more than a dozen regions with significant non-uniform distributions of earthquake occurrence time. In these regions, the ratio of χ ² to the number of degrees of freedom far exceeds five. As a result, we posit that some factors associated with the Sun–Earth–Moon relationship may trigger earthquake activity under certain temporal and spatial conditions.  相似文献   

Interferometry basics in practice: Exercises     

Florentin Millour  Damien Sgransan  Jean-Philippe Berger  Gilles Duvert  Fabien Malbet 《New Astronomy Reviews》2008,52(2-5):208

The following exercises aim to learn the link between the object intensity distribution and the corresponding visibility curves of a long-baseline optical interferometer. They are also intended to show the additional constraints on observability that an interferometer has.This practical session is meant to be carried out with the ASPRO software, from the Jean-Marie Mariotti Center, but can also be done using other observation preparation software, such as viscalc from ESO.There are two main parts with series of exercises and the exercises corrections. The first one aims at understanding the visibility and its properties by practicing with simple examples, and the second one is about UV coverage.  相似文献   

All you ever wanted to know about optical long baseline stellar interferometry, but were too shy to ask your adviser     

Florentin Millour   《New Astronomy Reviews》2008,52(2-5):177

I try to present a small view of the properties and issues related to astronomical interferometry observations. I recall a bit of history of the technique, give some basic assessments to the principle of interferometry, and finally, describe physical processes and limitations that affect optical long baseline interferometry and which are, in general, very useful for everyday work. Therefore, this text is not intended to perform strong demonstrations and show accurate results, but rather to transmit the general “feeling” one needs to have to not be destabilised by the first contact to real world interferometry.  相似文献   

蒙古中南部地区噪声层析成像   总被引：3，自引：2，他引：1       下载免费PDF全文

潘佳铁  吴庆举  李永华  余大新  高孟潭  M. Ulziibat  S. Demberel 《地球物理学报》2015,58(8):3009-3022

依托中蒙国际合作项目"远东地区地磁场、重力场及深部构造观测与模型研究",我们首次获取了蒙古中南部地区密集的地震台阵观测资料.本研究收集了69套宽频带台站2011年8月至2013年7月间的垂直向连续记录,利用噪声互相关方法计算了台站间的经验格林函数,并采用基于连续小波变换的频时分析方法,提取了1478条周期6~30s的瑞雷波的相速度频散曲线.利用DitmarYanovskaya方法,我们构建了研究区6~30s瑞雷波的高分辨率(0.5°×0.5°)相速度分布图.结果表明,蒙古中南部地区的地壳上地幔速度结构存在横向非均匀性,但并不显著(相对变化~±2%).短周期(如6s)的相速度分布与地表地质构造具有明显的相关性,具体来说,北部山盆显示为高速,南部盆地、戈壁滩均显示为低速;随着周期的增大(如15s,20s),地形的控制作用相对减弱.较长周期(30s)的相速度分布图上,南部的高速区进一步扩大,与南部地壳厚度较薄有关.蒙古主构造线南北两侧相速度分布有明显差异,暗示它不仅是地表地形和构造的分界线,而且还是地壳结构的分界线.从6~30s中戈壁一直显示为低速,可能与该区新生代火山活动有关;研究区北部杭爱山—肯特盆地一直显示为相对的高速,与该区具有较老、稳定的地层有关.  相似文献   

青藏高原东南部地区瑞雷波相速度层析成像   总被引：13，自引：7，他引：6       下载免费PDF全文

潘佳铁  李永华  吴庆举  丁志峰 《地球物理学报》2015,58(11):3993-4006

本研究收集了"中国地震科学探测台阵-南北地震带南段"项目325个流动宽频带台站于2011年8月至2012年9月记录的远震垂直向资料,利用双台法测得了3594条独立路径上的瑞雷波相速度频散曲线,反演得到了青藏高原东南部地区周期10~60s瑞雷波的相速度分布图像.空间分辨尺度图表明,在台站覆盖范围内的绝大部分地区横向分辨率达到50km.2D相速度分布图显示,青藏高原东南部地区地壳上地幔S波速度结构存在较明显的横向非均匀性.短周期(如10s)的相速度分布主要受地表沉积层厚度的影响.绝大多数地震发生在周期15s相速度图上的低速区或高低速的陡变梯度带附近,充分说明该区的强震活动与中上地壳速度结构的变化有直接关系.中等周期(如20~30s)的相速度分布主要与中下地壳速度结构、地壳厚度密切相关,小江断裂、松潘—甘孜块体呈现最显著的低速,可能暗示这两处的中、下地壳存在低速层.较长周期(如40~60s)的相速度分布与上地幔顶部热状态和构造活动(如岩浆作用)有关.滇西南地区表现为大范围的显著低速,可能暗示滇西南地区上地幔顶部物质存在部分熔融.不同构造块体下方的频散曲线,具有不同的相速度特征.腾冲火山下方的频散曲线在10~60s一直为较低的速度,尤其是到40s以后,相速度随周期的变大增速明显放缓,至60s比其他任何块体速度都低,暗示腾冲火山区下方的低速至少来自上地幔顶部(约100km).  相似文献   

利用瑞利面波相速度和方位各向异性研究鄂尔多斯块体的岩石圈变形特征   总被引：1，自引：1，他引：0       下载免费PDF全文

姚志祥  王椿镛  Eric Sandvol  陈永顺  曾融生 《地球物理学报》2014,57(9):2777-2789

利用在鄂尔多斯块体内部布设的45个宽频带流动台站和固定台站的资料,用双平面波方法反演了20~143 s共12个周期的基阶瑞利面波的平均相速度和方位各向异性,并反演了一维S波速度结构.反演结果显示50~100 s中长周期的瑞利面波相速度高于AK135速度模型的相速度,为高速异常,S波速度显示高速异常主要位于180 km深度范围内,表明鄂尔多斯块体保留有厚的高速岩石圈.20~111 s周期的方位各向异性强度小于1%,较小的各向异性表明鄂尔多斯块体岩石圈变形较弱.20~50 s周期的平均快波方向为近EW向,67~143 s周期的平均快波方向为NW-SE向,相对发生了整体改变,快波方向的转变约开始于80~100 km深度范围,这表明岩石圈上下部存在着由不同变形机制导致的各向异性.上部岩石圈中各向异性可能主要为残留的“化石”各向异性,而下部岩石圈各向异性可能是现今板块构造运动导致的变形而形成.鄂尔多斯块体岩石圈垂向上的变形差异可能主要与岩石圈温度随深度的变化以及青藏高原NE-NNE向挤压引起的上部岩石圈逆时针旋转有关.  相似文献   

Analytical solutions for benchmarking cold regions subsurface water flow and energy transport models: One-dimensional soil thaw with conduction and advection     

《Advances in water resources》2014

Numerous cold regions water flow and energy transport models have emerged in recent years. Dissimilarities often exist in their mathematical formulations and/or numerical solution techniques, but few analytical solutions exist for benchmarking flow and energy transport models that include pore water phase change. This paper presents a detailed derivation of the Lunardini solution, an approximate analytical solution for predicting soil thawing subject to conduction, advection, and phase change. Fifteen thawing scenarios are examined by considering differences in porosity, surface temperature, Darcy velocity, and initial temperature. The accuracy of the Lunardini solution is shown to be proportional to the Stefan number. The analytical solution results obtained for soil thawing scenarios with water flow and advection are compared to those obtained from the finite element model SUTRA. Three problems, two involving the Lunardini solution and one involving the classic Neumann solution, are recommended as standard benchmarks for future model development and testing.  相似文献   

东昆仑左行走滑韧性剪切带形成时代的锆石U-Pb年龄证据   总被引：2，自引：0，他引：2  

张紫程  张绪教  高万里  胡道功  陆露 《地质力学学报》2010,16(1):51-58

巴颜咯拉—松潘甘孜地体与东昆仑南地体晚三叠纪斜向碰撞形成大规模的东昆仑左行走滑韧性剪切带,新生代时期韧性剪切转为脆性左旋走滑并构成青藏高原向东逃逸的北部边界。为了确定早期韧性剪切变形时代,对剪切带上2个同构造花岗斑岩脉进行了激光探针(LA-MC-ICP MS)测年研究,获得了196.4 ± 2.3 Ma和195.1 ± 1.6 Ma的锆石206Pb/238U加权平均年龄,表明东昆仑左行走滑韧性剪切带形成于燕山早期。   相似文献   

去均值归一化互相关最小二乘逆时偏移及其应用   总被引：1，自引：1，他引：0       下载免费PDF全文

李庆洋  黄建平  李振春  李娜  李闯 《地球物理学报》2016,59(8):3006-3015

最小二乘逆时偏移相对于常规逆时偏移具有更高的成像分辨率、振幅保幅性及均衡性等优势,在一定程度上可满足岩性油气藏勘探的需求,是目前研究的热点之一.然而由于实际地下介质的黏滞性和变密度,以及无法准确地估计震源子波等,基于振幅匹配的常规最小二乘逆时偏移算法很难在实际资料处理中取得好的效果.此外,实际数据常包含大量噪声,进一步限制了常规算法的应用.为此,本文通过修改目标泛函,提出了去均值归一化的互相关最小二乘逆时偏移算法,并给出了陆上资料的应用实例.研究表明,归一化策略减弱了算法对子波能量的苛求;互相关算法强调相位匹配,进一步弱化了子波的影响,提升了算法的稳定性和可靠性;去均值思想在处理低信噪比资料方面有较大优势.理论模型和陆上实际资料处理都验证了本算法的有效性和对复杂模型的适应性.  相似文献   

武夷山成矿带桃溪隆起、岩浆侵入和区域铜多金属矿成矿作用   总被引：2，自引：0，他引：2  

陈世忠  马明  陈刚  周延  朱筱婷  邱金亮  毛建仁 《地球科学》2010,35(6):969-984

武夷山成矿带内矿区的最大特征就是分布有老地层和岩浆岩.老地层集中分布区——桃溪隆起区是武夷山隆起的一部分, 表现为变质核杂岩的特征, 其中分布着大中型铜多金属矿床和大量的多金属矿点, 如紫金山铜金矿、岩背锡矿和红山铜矿, 它们是武夷山成矿带乃至中国东部的典型特征.主要矿床的成矿年龄集中于130~90 Ma, 属燕山晚期; 成矿特征表现为斑岩型-岩浆热液型铜多金属矿.成矿斑岩体成岩时代90~140 Ma, 多为燕山期复式杂岩体的中晚期, 桃溪隆起区这种时空一致性是由于中生代晚期岩石圈拆沉的产物.桃溪隆起区在中生代晚期经历了岩石圈加厚期后的拆沉、软流圈物质侵入、岩浆作用及其伴随的成矿作用.这些认识对该区找矿部署具有重要的意义.   相似文献