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61.
为解决EDAS?24GN6数据采集器对策克台井下宽频带地震计GL?S120B进行正弦标定的过程中产生的响应波形限幅问题,分析了数据采集器?地震计这一系统的标定过程及原理,结合GL?S120B的幅频响应特征,推导出正弦标定频点参数中的频率f、衰减因子λ与标定响应波形限幅之间的关系。分析表明,在GL?S120B平坦响应频带内,为避免出现标定波形响应限幅,频率f与衰减因子λ的乘积应至少大于限幅下限50.93;而在其衰减响应频带内,由于地震计电压灵敏度的衰减,频率f与衰减因子λ的乘积最小取值也相应减小。据此,对衰减因子λ进行校正,并再次对GL?S120B进行正弦标定。标定及计算结果显示:标定波形未限幅,GL?S120B三分向幅频响应特征较为一致;灵敏度对出厂值的变化率保持在5%范围内。本研究结论可为采用EDAS?24GN6和GL?S120B地震观测系统的台站进行正弦波标定提供频点参数,并为其他台站解决正弦标定波形限幅问题提供分析依据。 相似文献
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Hongfeng Yang Dun Wang Rumeng Guo Mengyu Xie Yang Zang Yue Wang Qiang Yao Chuang Cheng Yanru An Yingying Zhang 《地震研究进展(英文)》2022,2(1):100113
The MS 6.9 Menyuan earthquake in Qinghai Province, west China is the largest earthquake by far in 2022. The earthquake occurs in a tectonically active region, with a background b-value of 0.87 within 100 ?km of the epicenter that we derived from the unified catalog produced by China Earthquake Networks Center since late 2008. Field surveys have revealed surface ruptures extending 22 ?km along strike, with a maximum ground displacement of 2.1 ?m. We construct a finite fault model with constraints from InSAR observations, which showed multiple fault segments during the Menyuan earthquake. The major slip asperity is confined within 10 ?km at depth, with the maximum slip of 3.5 ?m. Near real-time back-projection results of coseismic radiation indicate a northwest propagating rupture that lasted for ~10 ?s. Intensity estimates from the back-projection results show up to a Mercalli scale of IX near the ruptured area, consistent with instrumental measurements and the observations from the field surveys. Aftershock locations (up to January 21, 2022) exhibit two segments, extending to ~20 ?km in depth. The largest one reaches MS 5.3, locating near the eastern end of the aftershock zone. Although the location and the approximate magnitude of the mainshock had been indicated by previous studies based on paleoearthquake records and seismic gap, as well as estimated stressing rate on faults, significant surface-breaching rupture leads to severe damage of the high-speed railway system, which poses a challenge in accurately assessing earthquake hazards and risks, and thus demands further investigations of the rupture behaviors for crustal earthquakes. 相似文献
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Characteristics of water isotopes and hydrograph separation during the wet season in the Heishui River, China 总被引:4,自引:0,他引:4
Yuhong Liu Ningjiang Fan Shuqing An Xiaohua Bai Fude Liu Zhen Xu Zhongsheng Wang Shirong Liu 《Journal of Hydrology》2008,353(3-4):314-321
Runoff generation and dynamics is an important issue in watershed and water resource management, but the mechanism in large scale is unclear and site-dependent. For this reason, spatial variations of δD and δ18O of river water and their sources within large-area of the Heishui Valley of the upper Yangtze River in western China were investigated during the wet season. A total 117 river water samples were collected at 13 sampling sites located at the junction of the principal river course and its tributaries. The results showed no spatial variations of either δD or δ18O values existed among tributary sampling sites A, B, E, F, H and I during the wet season, and significantly spatial variation occurred between tributary sampling sites A, B, E, F, H, I and site K; which indicated different proportions of rain entering river water should lead to spatial variation of water isotopes. The hydrograph separation analysis, based on the isotope data of river water, meltwater and rain water samples, showed the contribution of snow and glacier meltwater varied from 63.8% to 92.6%, and that of rain varied from 7.4% to 36.2%; which meant that snow and glacier meltwater was the main supplying water source of baseflow in the Heishui Valley. And the roles of glacier and snow meltwater should be significantly noticed in water resource management in this alpine valley at the rim of the Tibetan Plateau. 相似文献
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地磁场模型和冠谐分析 总被引:4,自引:2,他引:4
地磁场是由内源场(地核场和地壳场)和外源场(电离层场和磁层场)组成的,地磁场模型是表示地磁场时空分布的数学表达式.本文简述了地磁场全球模型和区域模型的计算方法和应用;评述了冠谐分析方法及其在地磁学中的应用;介绍了地磁场模型误差的主要来源. 相似文献
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为使已获得的中国大陆中上地壳结构更为可靠,本文搜集了很多对浅部结构分辨率较好的短周期面波资料. 与传统面波层析成像反演方法不同,本文在第二步由面波频散得到剪切波速的过程中不再对每个结点进行一维波速模型分别反演,而是直接将所有结点上的区域化频散转换成三维波速结构的线性化约束,实现了直接的三维反演. 检测板测试结果显示该方法可以得到理想的反演结果. 本文得到的波速模型显示,中国大陆中上地壳的速度分布存在明显的横向变化和分区特征. 较低的波速异常很好地勾勒出我国主要的沉积盆地,波速异常在不同深度上的变化在一定程度上反映了各盆地结晶基底的深度. 以东经95deg;为界,特提斯构造域西部具有明显的低速异常,而东部基本没有低速异常. 基于油气资源多存在于沉积层中,而沉积层表现低速异常,我们推测特提斯构造域西部油气前景比东部好. 另外, 由于特提斯构造域西部低速非常明显,这可能也说明了其地壳温度较高. 兴安造山带的低速异常可能也说明了其地壳温度较高. 20 km深度上鄂尔多斯盆地西侧的弱低速带, 很好地勾勒出中国大陆近似沿105deg;经线的强震带的走势. 相似文献
68.
Three-dimensional thermal structure of the Chinese continental crust and upper mantle 总被引:7,自引:0,他引:7
We invert S-wave velocities for the 3D upper-mantle temperatures, in which the position with a temperature crossing the 1300℃ adiabat is corresponding to the top of the seismic low velocity zone. The temperatures down to the depth of 80 km are then calculated by solving steady-state thermal conduction equation with the constraints of the inverted upper-mantle temperatures and the surface temperatures, and then surface heat flows are calculated from the crustal temperatures. The misfit between the calculated and observed surface heat flow is smaller than 20% for most regions. The result shows that, at a depth of 25 km, the crustal temperature of eastern China (500―600℃) is higher than that of western China (<500℃). At a depth of 100 km, temperatures beneath eastern and southeastern China are higher than the adiabatic temperature of 1300℃, while that beneath west China is lower. The Tarim craton and the Sichuan basin show generally low temperature. At a depth of 150 km, temperatures beneath south China, eastern Yangtze craton, North China craton and around the Qiangtang terrane are higher than the adiabatic temperature of 1300℃, but is the lowest beneath the Sichuan basin and the regions near the Indian-Eurasian collision zone. At a depth of 200 km, very low temperature occurs beneath the Qinghai-Tibet Plateau and the south to the Tarim craton. 相似文献
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