2017年6月16日湖北秭归Ms4.3地震成因初探

北京时间2017年6月16日19时48分, 湖北省秭归县发生M_S4.3地震(震中位置31.06°N, 110.48°E)。 此次地震导致当地160多间建筑物出现不同程度损坏, 100多人生活受到影响, 震区中危岩体出现一定程度破坏。 分析此次地震的震源参数将有助于了解其震源特征和发震机制。 本文首先获取了震中距在3°以内的40个宽频带固定台站的三分量数据, 然后利用FK(Frequency wavenumber)方法计算了在不同深度下Crust2.0模型和改进的1-D模型的格林函数, 分别使用Cut And Paste(CAP)方法反演得到本次地震的震源机制解和深度; 并采用基阶Rayleigh波振幅谱进一步约束了质心深度。 结果表明此次地震的最佳震源机制解的节面Ⅰ: 68°/59°/163°; 节面Ⅱ: 166°/75°/32°, 最佳矩震级为M_W4.3, 最佳深度约为5 km。 对比2013年巴东地震、 2014年秭归地震以及2011年湖北阳新—江西瑞昌地震的震源参数和余震信息, 此次地震有可能是水库诱发地震, 但要判断成因还需进一步研究。     

STUDY ON FOCAL DEPTH OF THE MS5.4 CANGWU EARTHQUAKE IN GUANGXI

On July 31th, 2016, a magnitude 5.4 earthquake struck Cangwu Country, Guangxi Zhuang Autonomous Region, it was the largest earthquake recorded by Guangxi Seismological Network since it set up. The number of people affected by the earthquake had reached 20 000, and the direct economic losses caused by the earthquake were nearly 100 million Yuan. After the earthquake, USGS provided a global earthquake catalog showing that the focal depth of Cangwu earthquake was about 24.5km. However, the result given by the Global Centroid Moment Tensor showed the focal depth of this earthquake was 15.6km. However, the result obtained by Xu Xiaofeng et al. using CAP method was 5.1km. It was clear that the focal depths of Cangwu earthquake given by different institutions were quite different from each other. However, accurate focal depth of the earthquake has important significance for exploring the tectonic mechanism near the epicenter, so it is necessary to further determine the more accurate depth of the Cangwu earthquake. In order to further accurately determine the focal depth of Cangwu earthquake, we used the global search method for travel-time residual to calculate the focal depth of this earthquake and its error range, based on the regional velocity model, which is a one-dimensional velocity model of the Xianggui tectonic belt produced by the comprehensive geophysical profile. Then, we inverted the focal mechanism of this earthquake with the CAP method. Based on this, the focal depth of Cangwu M_S5.4 earthquake was further determined by the method of the Rayleigh surface wave amplitude spectrum and the sPL phase, respectively. Computed results reveal that the focal depth of this earthquake and its error range from the travel-time residual global search method is about(13±3)km, the focal depth inverted by CAP method is about 10km, the focal depth from sPL phase is about 10km, and the focal depth from Rayleigh surface wave amplitude spectrum is about 9~10km. Finally, we confirmed that the focal depth of Cangwu M_S5.4 earthquake is about 10km, which indicates that this earthquake still occurred in the upper crust. In the case of low network density, the sPL phase and Rayleigh wave amplitude spectrum recorded by only 1 or 2 broadband stations could be used to obtain more accurate focal depth. The focal depth's accuracy of Cangwu M_S5.4 earthquake in the USGS global earthquake catalog has yet to be improved. In the future, we should consider the error of the source parameters when using the USGS global earthquake catalog for other related research.     

陕西铜川新区典型滑坡在不同强度地震作用下的稳定性——以铜川玉皇阁水库滑坡为例

采用极限平衡法和有限元强度折减法,对地震作用下的陕西铜川新区玉皇阁水库滑坡的稳定性进行计算分析,对比分析2种方法在天然、中震、大震3个工况下的安全系数,结果基本吻合,且随着地震动峰值加速度的增大边坡稳定性逐渐降低,安全系数最大降低幅度可达18%;根据计算结果进行稳定性评价,玉皇阁水库滑坡在大震作用下处于不稳定状态,中震作用下其稳定性也较低。该结果为该滑坡风险评价和防控提供参考,为铜川新区地震地质灾害评价提供基础性参考。     

青岛日偏食对GPS定位精度的影响

2009年7月22日日全食期间,在青岛采用固定点监测单频GPS信号,同时利用非日食期的单频GPS信号监测数据统计对比分析认为,青岛发生的日偏食现象,对GPS单频接收系统的导航定位精度有影响.表现为误差有所增大,接收卫星数减少,PDOP值增大.短时位置偏差最大值为4.02m,历时2min 48s.但青岛地区日偏食对GPS...     

Change of ancient hydrology net in Northeast China Plain

Comparing with lithofacies palaeogeography of several great plains, the authors analyzed four great plains in Quaternary diastrophism, the sedimentary facies, sedimentary environment and their evolution from the independent embryonic and river system of ancient Heilongjiang finally to the Halar highland, Songnen Plain, Sanjiang Plain, the Xingkai Lake Plain and various river systems, collected the unification outside the system of Heilongjiang River to release into the sea, south ancient Xialiao River finally piracy Dongliao River, Xialiao River had released into the sea the ancient water law vicissitude and the evolved rule.     

城市排水管道健康状况检测与评估内外业流程一体化方案设计与应用

城市排水管道健康状况检测和评估是城市管理运营的重要内容之一,是及时发现排水管道安全隐患的有效措施,可为排水管道养护、改建、修复、运行提供科学准确的依据。因此,检测和评估报告本身的真实性、准确性、科学性显得尤为重要。本文详细介绍了城市排水管道健康状况检测和评估内外业流程一体化方案的设计及应用,具体从4个方面进行了阐述：①资源配置及方案设计依据的选择;②外业现场作业流程的设计;③内业作业流程的设计;④检测和评估报告内容纲要的设计及应用。     

微生物沉积碳酸钙固化珊瑚砂的试验研究

向珊瑚砂中注入巴斯德芽孢杆菌菌液、氯化钙和尿素的混合液,利用微生物沉积碳酸钙固化珊瑚砂;并对珊瑚砂固化体进行了渗透、强度及微观结构等试验。试验结果表明,巴斯德芽孢杆菌的活性随时间呈衰减趋势,但衰减速度缓慢,能较好地满足珊瑚砂固化的需要。随着菌液、氯化钙和尿素的混合液注入次数的增加,珊瑚砂柱渗透性逐步降低,最终渗透性降低了1～2个数量级。微生物固化后的珊瑚砂柱应力-应变曲线大致可分为3段,即应力随应变缓慢增加段、快速增加段以及突降段。试样发生压裂脆性破坏,无侧限抗压强度最高达到14 MPa左右。抗压强度随干密度增加而增大,随渗透性降低而增大。微生物固化后珊瑚砂颗粒被生成的碳酸钙完整的包裹,孔隙间极少见生成的碳酸钙,与普通硅砂微生物固化后的微观结构不同,较好地解释了渗透性降低不多的原因。     

基于OFDM的CDMA3G无线通信系统传输地震数据分析

OFDM是一种无线环境下的高速传输技术,它采用一种不连续的多调制技术,将不同载波中的大量信号合并成单一的信号,从而完成信号传送。由于这种技术具有在杂波干扰下传送信号的能力,因此常常会被利用在容易受外界干扰或者抵抗外界干扰能力较差的传输介质中。由于在OFDM系统中各个子信道的载波相互正交,它们的频谱是相互重叠的,这样不但减小了子载波间的相互干扰,同时又提高了频谱利用率。由于地震监测系统中需要传输大量数据,因此OFDM技术在地震监测系统中将有广泛的应用。     

隧道穿越引起地下管线竖向位移的能量变分分析方法

隧道穿越引起的地层位移可能造成地下管线变形过大或断裂等事故,引起工程界的高度关注。基于假定的地下管线竖向位移分布模式,通过能量方法建立变分控制方程,提出了求解隧道穿越地下管线竖向位移的能量变分解法,运用叠加原理将单线隧道解答延拓至双线隧道中。与离心机试验和工程实例的对比,验证了方法的正确性。通过参数计算,分析了管材弹性模量、管线埋深、地层损失率等相关因素对地下管线竖向位移的影响规律,研究结论具有工程参考价值。     

扩展的证据理论在遥感影像围填海检测中的应用

针对全国海域使用情况的监测需求,本文应用扩展的证据理论进行围填海区域检测,预设类别空间为{围填海,海水}。实验结果显示基于扩展的证据理论不仅能够较准确地检测出围填海区域,而且将浅海中的水下沙脊或小岛划分为不确定的未知类别。说明扩展的证据理论能够更好地完成围填海的检测,体现了扩展的证据理论解决实际问题的能力,同时,也为全海域的围填海监测提供了新的思路和扩展空间。