天文CCD片内放大器的噪声特性及其抑制方法

分析了低光度天文应用时CCD器件的主要噪声源的噪声特性和三种典型CCD读出信号处理方式的噪声抑制效果;提出了天文CCD读出信号的相关多次采样(CMS)处理新方法,并分析了四次采样抑制CCD读出噪声的实验结果。     

区域震相初至估计

本在地震数据自动化处理中，给出一种基于自回归模型的Akaike information criteria(AIC)算法和信号平均幅值比的混合方法来估计地震信号的初至．用信号的AIC曲线和平均幅值比曲线构造一种叠加曲线，再进行类似于坐标旋转的校正，可以准确估计低信噪比记录中信号的初至，尤其对于震相类型比较复杂的后续震相(如S波、Lg波)的初至估计结果很好．通过对中国数字地震台网乌鲁木齐台记录到的23次天然地震中P波、S波和Lg波的初至估计，与人工分析结果相比，P波初至估计的均方误差为0．71s，后续震相(S波、Lg波)的均方误差为1．64s，优于传统AIC算法的估计结果．     

Influence of earthquake frequency content on soil dynamic properties at CAO site

The installation of vertical downhole arrays in the field that record the soil behavior during earthquakes, has opened the opportunity of exploring another alternate method for assessing the soil dynamic properties by solving the inverse problem. This article proposes a methodology for solving this problem using spectral analysis of downhole arrays records. The one-dimensional shear wave propagation model was used, considering a homogeneous-viscoelastic medium. This methodology was applied at the site known as Central de Abasto Oficinas (CAO), which is located in the lake zone of the Mexico City. The results indicate that even relatively low frequencies have a noticeable effect on dynamic soil properties. Shear modulus increases and damping ratio lessens when the frequency rises.     

Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake

A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55 km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance to fault, fault rupture directivity, site condition, as well as thrust of hanging wall. Compared with empirical strong ground motion attenuation relations used in China, US and Japan, the PGAs and PGVs recorded in this earthquake are not as large as what we have expected for a large earthquake as magnitude 7.6. However, the largest PGV and PGD worldwide were recorded in this event, which are 292 cm/s and 867 cm, respectively. Caused by nonlinear site effects of soil, peaks and corresponding ratios on E-class site were markedly different from those on other sites. Just as observed in historic earthquakes, fault rupture directivity effects caused significant differences between peaks of ground motion of two horizontal components, but took very slight effects on the duration of ground motion. The significant velocity pulses associated with large PGVs and PGDs, as well as large permanent displacements, which may result from the large thrust of the hanging wall, became the outstanding character of this event. Based on this study, we point out that 3D waveform modeling is needed to understand and predict near fault ground motion of large earthquakes.     

山洞电源、信号线路改造与接地网建设相关技术探讨

本文对铁岭地震台在山洞电源，信号线路改造与接地网建设中遇到的问题及解决的办法做简要介绍，依据洞室固有条件，结合《规范》要求，探讨了监测环境建设施工经验。     

地震电磁辐射数字化观测方法及异常信号分析

地震电磁辐射观测对短临预报非常有意义,讨论了以计算机为核心的数字化观测系统的可行性与必要性,并给出了实际观测系统的设计方法。数字化系统具有观测灵敏度高,便于观测信号的实时分析识别,便于应用算法提取短临预报的有用信息和便于观测台网间数据交流与处理等优点,基于对观测信号的时域,频域分析的比较,给出干扰信号与异常电磁辐射信号的判别方法。     

The role of visual saliency in the automation of seismic interpretation

In this paper, we propose a workflow based on SalSi for the detection and delineation of geological structures such as salt domes. SalSi is a seismic attribute designed based on the modelling of human visual system that detects the salient features and captures the spatial correlation within seismic volumes for delineating seismic structures. Using this attribute we cannot only highlight the neighbouring regions of salt domes to assist a seismic interpreter but also delineate such structures using a region growing method and post‐processing. The proposed delineation workflow detects the salt‐dome boundary with very good precision and accuracy. Experimental results show the effectiveness of the proposed workflow on a real seismic dataset acquired from the North Sea, F3 block. For the subjective evaluation of the results of different salt‐dome delineation algorithms, we have used a reference salt‐dome boundary interpreted by a geophysicist. For the objective evaluation of results, we have used five different metrics based on pixels, shape, and curvedness to establish the effectiveness of the proposed workflow. The proposed workflow is not only fast but also yields better results as compared with other salt‐dome delineation algorithms and shows a promising potential in seismic interpretation.     

利用EMD和子波振幅谱与相位谱关系的时变子波提取方法

本文首先分析了地震波在黏弹介质的传播规律,基于黏弹介质地震波动方程总结了时变子波振幅谱和相位谱的关系,从而得出结论,准确估计子波相位谱初值和不同时刻的子波振幅谱是实现时变子波准确提取的必要条件.在此基础上,针对传统方法限制子波振幅谱形态且受限于分段平稳假设的问题,提出了一种利用EMD(Empirical Mode Decomposition)和子波振幅谱与相位谱关系的时变子波提取方法,根据子波对数振幅谱光滑连续而反射系数对数振幅谱振荡剧烈的特点,采用EMD方法将不同时刻地震记录的对数振幅谱分解为一组具有不同振荡尺度的模态分量,通过滤除振荡剧烈分量、重构光滑连续分量提取时变子波振幅谱;再应用子波振幅谱和相位谱的关系提取时变子波相位谱,将分别提取的振幅谱和相位谱逐点进行合成,最终实现时变子波的准确提取.本文方法不需要求取Q值,适用于变Q值的情况,具有良好的抗噪性能.数值仿真和叠后实际资料处理结果表明,相比传统的分段提取方法,利用本文方法提取的时变子波准确度更高,研究成果对提高地震资料分辨率具有重要意义.     

2020年1月19日新疆伽师MS6.4地震强震动记录特征初步分析

2020年1月19日新疆伽师发生M S6.4地震,新疆强震动观测台网共获取44组强震动记录,西克尔强震台获得本次地震最大峰值加速度633.3×10-2 m·s-2。本文对获取到的强震动记录进行初步整理、分析,拟合得到本次地震地震动峰值加速度衰减关系,在300 km范围内与经验性衰减关系相差不大。计算分析了峰值加速度大于100×10-2 m·s-2的5个典型强震台站加速度反应谱,并与设计反应谱进行对比分析,同时计算了这5个台站地震动70%及90%能量持时,两者相差较大,反映出地震主要能量释放集中在相对较短的时间内。