COSEISMIC DISPLACEMENT FIELD OF THE WENCHUAN EARTHQUAKE DERIVED FROM STRONG MOTION RECORDS AND APPLICATION IN SLIP INVERSION

The development of high-rate GNSS seismology and seismic observation methods has provided technical support for acquiring the near-field real-time displacement time series during earthquake. But in practice, the limited number of GNSS continuous stations hardly meets the requirement of near-field quasi-real-time coseismic displacement observation, while the macroseismographs could be an important complement. Compared with high-rate GNSS, macroseismograph has better sensitivity, higher resolution(100~200Hz)and larger dynamic range, and the most importantly, lower cost. However, baseline drift exists in strong-motion data, which limits its widespread use. This paper aims to prove the feasibility and reliability of strong motion data in acquiring seismic displacement sequences, as a supplement to high-rate GNSS. In this study, we have analyzed the strong-motion data of Wenchuan M_S8.0 earthquake in Longmenshan fault zone, based on the automatic scheme for empirical baseline correction proposed by Wang et al., which fits the uncorrected displacement by polynomial to obtain the fitting parameters, and then the baseline correction is completed in the velocity sequence. Through correction processing and quadratic integration, the static coseismic displacement field and displacement time series are obtained. Comparison of the displacement time series from the strong motions with the result of high-rate GPS shows a good coincidence. We have worked out the coseismic displacement field in the large area of Wenchuan earthquake using GPS data and strong motion data. The coseismic displacement fields calculated from GPS and strong motions are consistent with each other in terms of magnitude, direction and distribution patterns. High-precision coseismic deformation can provide better data constraint for fault slip inversion. To verify the influence of strong-motion data on slip distribution in Wenchuan earthquake, we used strong motion, GPS and InSAR data to estimate the stress drop, moment magnitude and coseismic slip model, and our results agreed with those of the previous studies. In addition, the inversion results of different data are different and complementary to some extent. The use of strong-motion data supplements the slip of the fault in the 180km segment and the 270~300km segment, thus making the inversion results of fault slip more comprehensive. From this result, we can draw the following conclusions:1)Based on the robust baseline correction method, the use of strong motion data, as an important complement to high-rate GNSS, can obtain reliable surface displacement after the earthquake. 2)The strong motion data provide an effective method to study the coseismic displacement sequence, the surface rupture process and quick seismogenic parameters acquisition. 3)The combination of multiple data can significantly improve the data coverage and give play to the advantages of different data. Therefore, it is suggested to combine multiple data(GPS, strong motion, InSAR, etc.)for joint inversion to improve the stability of fault slip model.     

火电厂粉煤灰的矿物磁性及其环境意义

火电厂排放的粉煤灰是重要的大气颗粒污染物之一,利用粉煤灰的磁性监测环境污染是新近发展的新手段。应用矿物磁测技术和X射线衍射对浙江省主要电厂排放的粉煤灰的矿物磁性特征和磁性矿物学,以及与重金属元素的关系进行了研究,结果表明粉煤灰具有较高的磁化率（X）、软剩磁（IRM20mT）和饱和等温剩磁（SIRM）值,粉煤灰频率磁化率（Xfd）的平均值为2．5％,磁性矿物以多畴（MD）颗粒存在,粉煤灰的剩磁矫顽力（BCR）在42～53mT之间。矿物测试结合X射线衍射分析表明粉煤灰中的氧化铁矿物以FeO4和Fe2O3-α为主,粉煤灰的磁化率与Fe、Mn、Pb、Zn、Cu、CA含量呈显著线性正相关,相关系数（r）分别是0．924,0．866,0．725,0．756,0．945和0．867,磁化率可作为粉煤灰中重金属元素含量的代用指标。     

高温高压下辉石岩的电导率实验研究

使用YJ-3000t紧装式六面顶高压设备和1260阻抗／增益-相位分析仪,在1．0～4．0GPa和773～1134K下用阻抗谱法就位测定了辉石岩的电导率。实验结果表明,电导率对频率具有很强的依赖性;温度是决定辉石岩电导率的一个重要物理参数,电导率随着温度升高而增大,lgσ与I／T之间符合Arrenhius关系式;随着压力升高。电导率降低,活化焓和独立于温度的指前因子亦降低。     

几款全球海底地形模型比较分析

近几十年,随着卫星测高技术和相关数据精密处理技术发展,依托卫星测高技术业已成为快速获取全球海底地形数据的可靠手段,国内外相关组织机构已发布了一系列全球海底地形模型。整理评述了多款全球海底地形的基本情况,以及相互间的内在联系,包括DBDB系列模型、ETOPO系列模型、Sandwell系列模型、GEBCO系列模型、SRTM+系列模型、EARTH地形球谐系数模型、BAT_VGG模型、BAT_WHU2020模型、STO_IEU2020模型等。通过对全球海底地形模型的认识和梳理,以期为下一步全球海底地形模型高效、低成本构建提供方法参考。     

USE OF SEISMIC WAVEFORMS AND INSAR DATA FOR DETERMINATION OF THE SEISMOTECTONICS OF THE MAINLING MS6.9 EARTHQUAKE ON NOV.18, 2017

On November 18, 2017, a M_S6.9 earthquake struck Mainling County, Tibet, with a depth of 10km. The earthquake occurred at the eastern Himalaya syntaxis. The Namche Barwan moved northward relative to the Himalayan terrane and was subducted deeply beneath the Lhasa terrane, forming the eastern syntaxis after the collision of the Indian plate and Asian plates. Firstly, this paper uses the far and near field broadband seismic waveform for joint inversion (CAPJoint method)of the earthquake focal mechanism. Two groups of nodal planes are obtained after 1000 times Bootstrap test. The strike, dip and rake of the best solution are calculated to be 302°, 76° and 84° (the nodal plane Ⅰ)and 138°, 27° and 104° (the nodal plane Ⅱ), respectively. This event was captured by interferometric synthetic aperture radar (InSAR)measurements from the Sentinel-1A radar satellite, which provide the opportunity to determine the fault plane, as well as the co-seismic slip distribution, and assess the seismic hazards. The overall trend of the deformation field revealed by InSAR is consistent with the GPS displacement field released by the Gan Wei-Jun's team. Geodesy (InSAR and GPS)observation of the earthquake deformation field shows the northeastern side of the epicenter uplifting and the southwestern side sinking. According to geodetic measurements and the thrust characteristics of fault deformation field, we speculate that the nodal plane Ⅰ is the true rupture plane. Secondly, based on the focal mechanism, we use InSAR data as the constraint to invert for the fine slip distribution on the fault plane. Our best model suggests that the seismogenic fault is a NW-SE striking thrust fault with a high angle. Combined with the slip distribution and aftershocks, we suggest that the earthquake is a high-angle thrust event, which is caused by the NE-dipping thrust beneath the Namche Barwa syntaxis subducted deeply beneath the Lhasa terrane.     

北海区海岛保护现状研究

海岛是壮大海洋经济的重要依托,是保护海洋环境、维护生态平衡的重要平台,北海区海岛对于北方地区经济发展和生态保护具有重要的意义。文章在对北海区海岛概况进行介绍的基础上,研究了北海区三省一市各级海岛管理部门在保护海岛生态环境、规范海岛开发秩序、改善海岛人居环境以及增强特殊用途海岛保护力度等海岛保护方面取得的进展,同时还分析了在北海区海岛保护中存在着海岛保护规范和制度不够健全、海岛管理业务化技术支撑体系建设进程缓慢、海岛及其周边生态系统相关研究不足、海岛保护与开发经费投入不足、公众海岛保护意识薄弱等问题。最后根据北海区海岛保护中存在的问题,提出了北海区海岛保护的改进建议。     

基于InSAR和GPS观测数据的尼泊尔地震发震断层特征参数联合反演研究

利用日本ALOS-2和欧空局Sentinel-1A卫星获得的尼泊尔地震同震形变场,结合GPS同震位移数据,联合反演了断层滑动分布特征和空间展布.结果表明:尼泊尔地震的同震形变场主要集中在150km×100km的范围内,且分为南北两个相邻的形变中心,南形变中心的视线向抬升量约为1.2m,北形变中心的视线向沉降量约为0.8m,均位于发震断层上盘.位于形变抬升区的KKN4和NAST两个GPS站,抬升量和南向运动量均达到了m级,而远离震区的其他GPS台水平和垂直观测量均在1cm以内.联合反演得到的断层位错分布主要集中在沿走向150km,沿倾向70km的范围内,最大滑动量为5.59m,平均滑动量为0.94m.断层面倾角在浅部约为7°,随着深度增加,倾角逐渐变大,到垂直深度20km时倾角接近12°;5月12日MW7.2级余震位于主震破裂区的"凹"型滑动缺损区域;主震破裂区的上边界与MBT空间位置十分吻合,主震破裂区主要集中的MBT以北50~60km处,垂直深度为8~9km,倾角为9°,继续向北时主震破裂面以10°~12°的倾角向深延伸,在18~20km可能与MHT交汇.因此,初步判定MBT为此次地震的发震断层.     

电网GIS全过程管理及数据获取技术研究

针对电网GIS数据的及时性维护、低压及营销用户设备的数据获取存在的较大需求,通过对电网GIS在不同环节、不同业务部门的数据管理需求及维护流程的研究,提出了一套安全、规范、高效的电网GIS数据全过程管理体系,探讨了移动终端安全通信及自动采集过程中涉及的关键技术。该研究成果有利于保证电网GIS数据的整体性、完整性、准确性和及时性,能够推动平台及各业务系统的实用化,推进了智能电网的信息化建设。     

基于热异常信息与BP神经网络的中强地震预测试验

地震预测是地震科学研究的主要领域之一。震前热异常现象(地表温度异常升高)普遍存在并且与地震三要素有复杂的非线性关系。文中结合神经网络的优点,提出将热异常信息作为地震预测的信息源,通过构建神经网络,进行地震预测的思路,并进行了试验。基于8d合成的1km分辨率的MODIS数据,利用RST算法提取震前热异常信息,在分析震前热异常信息时空变化的基础上,确定出BP神经网络的结构,利用该网络对中国及周边100个5级以上震例,以及70个随机无震样本进行训练和仿真。试验结果表明,通过RST算法提取的震前热异常指数值,用于BP神经网络地震预测是可行的,其预测的试验结果刻画出了地震要素与热异常值间的非线性相关性。未来预测区域范围的选取以及神经网络中隐层神经元的数量将对地震预测效果产生较大的影响。     

东北地区城市民生质量测度与空间分析

民生问题是当今中国政府和民众高度关注的热点问题,也是全面建成小康社会进程中需要迫切解决的关键科学问题。借鉴当代中国人的价值观结构,构建了民生质量评估指标体系,定量测度了东北地区34个地级市的民生质量指数,并采用ESDA和多元线性回归模型探讨其空间分异特征及其影响因素。研究结果表明：① 东北地区城市民生质量呈等级分布特征,且“两极分化”明显。② 经济实力、产业结构、城市化和地理邻近性对民生质量空间分异有重要影响。