辽宁测震台网台站选取对地震速报定位结果的影响     

李子昊  王承伟  李恩来  安祥宇  梁一婧 《防灾减灾学报》2020,(1):26-32

选取2015-2018年辽宁测震台网记录的10条M_L>2.5的三种类型地震,运用3~20个台站分别对地震进行重新定位,将得出的结果与编目结果进行对比,最终得到一个线性曲线。结果表明,对于网缘地震应选取8~10个台站,网内地震选取5~7个台站进行定位可以保证速报结果的准确和速度。  相似文献   

A hybrid optimization scheme for self-potential measurements due to multiple sheet-like bodies in arbitrary 2D resistivity distributions     

Iraklis Giannakis  Panagiotis Tsourlos  Costas Papazachos  George Vargemezis  Antonios Giannopoulos  Nikos Papadopoulos  Fabio Tosti  Amir Alani 《Geophysical Prospecting》2019,67(7):1948-1964

Self-potential is a passive geophysical method that can be applied in a straightforward manner with minimum requirements in the field. Nonetheless, interpretation of self-potential data is particularly challenging due to the inherited non-uniqueness present in all potential methods. Incorporating information regarding the target of interest can facilitate interpretation and increase the reliability of the final output. In the current paper, a novel method for detecting multiple sheet-like targets is presented. A numerical framework is initially described that simulates sheet-like bodies in an arbitrary 2D resistivity distribution. A scattered field formulation based on finite differences is employed that allows the edges of the sheet to be independent of the grid geometry. A novel analytical solution for two-layered models is derived and subsequently used to validate the accuracy of the proposed numerical scheme. Lastly, a hybrid optimization is proposed that couples linear least-squares with particle-swarm optimization in order to effectively locate the edges of multiple sheet-like bodies. Through numerical and real data, it is proven that the hybrid optimization overcomes local minimal that occurs in complex resistivity distributions and converges substantially faster compared to traditional particle-swarm optimization.  相似文献   

基于尺度空间技术的归一化Facet模型位场边界识别   总被引：1，自引：0，他引：1       下载免费PDF全文

胡双贵  汤井田  任政勇  周聪  肖晓 《地球物理学报》2019,62(1):331-342

边界识别是位场数据处理解释中的重要环节,传统边界识别方法通常不能均衡深、浅部地质体边界.基于尺度空间技术和归一化的Facet模型检测算子,本文开发了一种带通空间滤波和边缘检测相结合的边界识别方法,有效地提高位场数据边界识别的精度和可靠性.为了验证本文算法的有效性和稳定性,分析了不同尺度空间函数和检测算子对算法的影响,并且对比了传统边界识别方法的效果.理论模拟和实际数据分析表明,利用位场垂向二阶导数进行的基于尺度空间技术的归一化Facet模型边界识别方法不仅算法的稳定性强,而且可以避免高阶导数对噪声干扰放大作用,同时均衡深部和浅部地质体边界,从而可以更精确地识别地质体的形态.  相似文献   

关于速报深远震问题的探讨     

阚丹  何家斌  王力平  戴玉明 《地震地磁观测与研究》2006,27(6):67-72

通过分析云南数字地震台网1998~2006年的地震记录资料,给出了该台网的深远地震震相记录特征,避免了常规分析方法中将深远地震误作浅源地震而带来的定位误差;利用1978年1月~2005年8月的深远地震记录资料,绘制了全球深远地震震中分布图,以作为地震速报的参考。  相似文献   

Potential Evapotranspiration Characteristic and Its Abrupt Change Across the Qinghai-Tibetan Plateau and Its Surrounding Areas in the Last 50 Years   总被引：1，自引：0，他引：1  

Tianci Yao  Hongwei Lu  Qing Yu  Wei Feng 《地球科学进展》2020,35(5):534-546

Daily routine observation data from 274 meteorological stations in the Qinghai-Tibetan Plateau and its surrounding areas from 1970 to 2017 were utilized to examine the spatial patterns and abrupt changes of potential evapotranspiration with the formula of FAO Penman-Monteith, in consideration of China’s eco-geographical divisions. The results showed that \mathrm{①} annual and seasonal average potential evapotranspiration, except for summer and winter, displayed a distinct spatial pattern in the Qinghai-Tibetan Plateau and its surrounding areas, with higher values in the north and south but lower values in the middle; the time when monthly potential evapotranspiration reached its maximum or minimum showed clearly zonal differences, namely earlier in the south and later in the north. \mathrm{②} The prevailing mean and trend abrupt changes of potential evapotranspiration were observed in the study area, while there were large differences in the abrupt change time in different regions and seasons. Specifically, the mean abrupt change was dominated by positive mutation, with generally the earliest abrupt change time occurring in spring and the latest appearing in winter; the trend abrupt change pattern was mainly described as the process shifting from a downward trend to an upward trend, the trend change points in year, spring, autumn and winter were postponed gradually from the northeast to the southwest with a delay of about 20, 10, 20 and 5 years, respectively. Comparatively, the abrupt change time of potential evapotranspiration trend in the whole plateau was later than that in the whole buffer zone, with a respective lag of 5, 1, 12, 5 and 4 years. \mathrm{③} Corresponding to the periodic change of potential evapotranspiration, significant evaporation paradox only scattered through the study area during the period before the trend change point (2007), but it was absent afterwards and would not appear in the future. The above findings will provide a scientific basis for further understanding the climate change and eco-hydrological process of the Qinghai-Tibetan Plateau and its surrounding areas in global warming.  相似文献   

阿尔山市地表干湿分布特征与生态环境的关系     

杨忠霞  范洪刚  李振海  杨忠云 《内蒙古气象》2009,(3):27-29

利用阿尔山市的气象资料,分析了1971—2007年地表潜在蒸散量和湿润指数的变化特征。结果表明:(1)从20世纪80年代以来,阿尔山市地表潜在蒸散量一直呈增大的趋势。(2)从对湿润指数(K)、潜在蒸散量(Eti)、年降水量(R)、年平均气温(T)的趋势分析看,阿尔山市干旱化有加重的趋势,降水有集中的趋势,阶段性干旱有增多加重的发展趋势,从而导致阿尔山市生态环境趋于恶化。  相似文献   

双差定位法在三峡库区地震定位中的应用   总被引：12，自引：5，他引：7  

张爱民  李强 《大地测量与地球动力学》2006,26(3):73-77

基于三峡地震台网2003年5月19日至2005年8月的地震记录资料,用双差定位法对发生于三峡库区(30.5°～31.5°N、109.5°～111.5°E)的1676次地震进行了重新定位。重新定位后的地震最大偏移量为10.93km,最小为0.08km,平均偏移量为1.87km,平均震源深度为6.59km。  相似文献   

2015年天津市海洋生态红线区海洋环境质量综合评价          下载免费PDF全文

徐冠球  张秋丰  屠建波  孙欢  何荣  刘洋 《海洋开发与管理》2018,35(1):120-125

文章于2015年夏季对天津市海洋生态红线区的主要海域进行了水质和沉积物环境状况调查。天津市海洋生态红线区海域海水主要受到了无机氮和活性磷酸盐的污染,部分站位化学需氧量、油类和铅等监测因子也超出了第二类海水水质标准的要求。总体上看,红线区海域海水处于中度富营养化状态,富营养化程度的高值区出现在生态红线区北部近岸海域。表层沉积物质量良好,均符合第一类海水沉积物质量标准,红线区海域表层沉积物重金属的潜在生态风险等级处于轻微等级。  相似文献   

Comparison of hydroelastic computer codes based on the ISSC VLFS benchmark     

H.R. Riggs  Hideyuki Suzuki  Jang Whan Kim 《Ocean Engineering》2008,35(7):589-597

There has been substantial development in computer codes for linear hydroelasticity in recent years, driven in part by the motivation to investigate the wave-induced response of very large floating structures (VLFSs). A recent International Ship and Offshore Structures Congress (ISSC) state-of-the-art report on VLFS design and analysis [ISSC, 2006. Report of Specialist Task Committee VI.2, very large floating structures. In: Frieze, P.A., Shenoi, R.A. (eds.), Proceedings of the 16th International Ship and Offshore Structures Congress, Elsevier, Southampton, UK, pp. 397-451] included a brief comparative study of the simulation results from different computer codes for a pontoon (mat-like) VLFS. The codes covered a mix of both fluid models (potential and linear Green-Naghdi) and structural models (3-D grillage, 2-D plate, 3-D shell). A more detailed comparison of the results from a select group of models from that study is provided and discussed herein. The similarities in the results increase the confidence level of the state-of-the-art in predicting the hydroelastic response of such structures, and the differences, including in computational efficiency, lead to an understanding of the significance of specific modeling assumptions and their impact on the predicted response.  相似文献   

运城盆地秋冬季PM_2.5传输特征和源区分析          下载免费PDF全文

刘婉莉  闫世明  王雁  李冬梅  贺钰清  张倩倩 《沙漠与绿洲气象(新疆气象)》2022,16(3):119-126

利用2017-2019年空气质量监测数据，采用HYSPLIT后向轨迹模式、聚类分析、潜在源贡献因子分析法（PSCF）和浓度权重轨迹分析法（CWT），对运城市秋冬季大气PM2.5传输路径、对应重污染的天气形势和潜在源区进行分析。结果表明：（1）运城近地层盛行偏东风时污染频率高，弱的偏东风和西南风时，污染物浓度较大。秋冬季PM2.5后向轨迹西北方向最多达53.53%，偏东方向最少为11.25%，偏西方向和西南方向介于两者之间，分别为16.61%和12.06%。（2）不同轨迹对应天气形势不同，西北和偏西轨迹下，500 hPa高度场上为两槽一脊或偏西气流，700～850 hPa受脊前西北气流影响，地面为高压前底部型或均压场型；西南轨迹下，500 hPa高度场上为偏西气流，700～850 hPa运城处于槽前西南气流，地面气压场为高压前底部（底部）或均压场。（3）运城PM2.5潜在源区主要位于陕西南部、四川东部和新疆东南、甘肃的东南部等地区，说明影响运城秋冬季PM2.5的浓度除了来自汾渭平原西南部的颗粒物区域输送，来自西北方向新疆、甘肃的远距离颗粒物传输也是重要来源。  相似文献