Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula,Iceland

We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992–1999 and 2003–2008 as well as GPS data from 2000–2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10 cm is observed during the first 2 years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction.     

各向同性薄层反射理论地震图

本文在各向同性介质假设下,计算了薄层顶、底反射P波和PS波的理论地震图.理论模拟发现薄层的反射P波与PS波是一复合波,包括层内的多次透射和反射转换波型,且具有类似单一界面反射的、脉冲式的波形特征.两类薄层反射整体振幅随着薄层厚度的降低而缩小;在地震子波主频40 Hz条件下,2 m左右厚度的薄层反射相比单一界面反射具有等同的振幅水平.1 m以下极薄层仅有弱反射甚至无反射;薄层反射复合波振幅与炮检距的关系依然成立,但不惟一;单界面反射AVO原理、方法不适用于薄层反射解释与反演.     

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????ROI_PAC????????????????ALOS PALSAR 474?????4?????????ERA-Interim?????NeQuick?????????????ж?????????????????????????????λ???????5??GPS?????????????????б????????????????????????????D-InSAR???ó?????λ????侭????????????????????????λ?????GPS??????????????????0.104 m?????????????0.057 m,???????????????????????????????D-InSAR?????????????     

Assimilating ASAR data for estimating soil moisture profile using an ensemble Kalman filter

Active microwave remote sensing data were used to calculate the near-surface soil moisture in the vegetated areas. In this study, Advanced Synthetic Aperture Radar （ASAR） observations of surface soil moisture content were used in a data assimilation framework to improve the estimation of the soil moisture profile at the middle reaches of the Heihe River Basin, Northwest China. A one-dimensional soil moisture assimilation system based on the ensemble Kalman filter （EnKF）, the forward radiative transfer model, crop model, and the Distributed Hydrology-Soil-Vegetation Model （DHSVM） was developed. The crop model, as a semi-empirical model, was used to estimate the surface backscattering of vegetated areas. The DHSVM is a distributed hydrology-vegetation model that explicitly represents the effects of topography and vegetation on water fluxes through the landscape. Numerical experiments were con- ducted to assimilate the ASAR data into the DHSVM and in situ soil moisture at the middle reaches of the Heihe River Basin from June 20 to July 15, 2008. The results indicated that EnKF is effective for assimilating ASAR observations into the hydrological model. Compared with the simulation and in situ observations, the assimilated results were significantly improved in the surface layer and root layer, and the soil moisture varied slightly in the deep layer. Additionally, EnKF is an efficient approach to handle the strongly nonlinear problem which is practical and effective for soil moisture estimation by assimilation of remote sensing data. Moreover, to improve the assimilation results, further studies on obtaining more reliable forcing data and model parameters and increasing the efficiency and accuracy of the remote sensing observations are needed, also improving estimation accuracy of model operator is important.     

应用多种来源重力异常编制中国海陆及邻区空间重力异常图及重力场解读

本文通过分析陆地实测空间重力异常数据、海洋船载测量空间重力异常数据、卫星测高重力异常,布格重力异常数据、EGM2008地球重力模型数据等多种来源数据的性质和精度,并对相关数据进行对比,研究了编制1:500万中国海陆空间重力异常图的数据使用方案和技术方法.在地形较为平坦、实测数据分布均匀的陆区,使用实测数据,在地形复杂,实测数据稀少以及没有实测数据的陆区或岛屿,利用布格重力异常反推空间异常的方法合成平均空间重力数据,西藏地区的数据对比实验证明合成平均空间重力异常数据是一种有效的数据补充.利用三观测列方差分解法在南海地区对船载测量空间重力数据和美国SS系列及丹麦DNSC08GRA卫星重力数据进行了方差分解计算,结果表明不同来源的卫星测高重力数据具有很大的一致性,数据精度较以往有了很大的提高.海区空间重力数据使用原则是在船载重力测量数据校准下,全面使用卫星测高重力数据进行编图.海陆过渡区的异常处理应以EGM2008地球重力模型重力场为基准参考场,实现海陆异常平缓过渡,无缝连接.对中国海陆空间重力异常场进行了小波变换处理,对空间重力异常场进行了解读,勾画出三横四竖的一级重力梯级带及其所围限的8个一级重力异常区,并划分了二级重力异常区和梯级带,为块体构造学体系中大地构造格架的建立提供了地球物理证据.     

InSAR技术及其在沧州地面沉降监测中的应用

随着城市建设的飞速发展,地面沉降危害日益显著,常规的测量方法尽管精度高,但是成本高、采样精度低、测量时间周期长,已经无法满足当今社会的要求。合成孔径雷达干涉测量(InSAR)已成为测量地球表面变化极具潜力的技术,它可以大面积的采样、测量时间短,同时成本也很低。沧州地区至2001年沉降中心累计沉降量已达2236mm。文中介绍用合成孔径雷达干涉测量进行沧州地区地面沉降监测的试验,最后利用InSAR的差分技术得到的沧州地区的地面沉降监测结果,并据此得到一些初步认识。     

中国反射地震"陆相断陷模型"简介

为了提高反射地震数据处理方法研究水平 ,验证各种速度建模及偏移成像算法的实用效果 ,ＩＦＰ(ＩｎｓｔｉｔｕｔＦｒａｎｃｏｉｓｄｅＰｅｔｒｏｌｅ)、ＳＥＧ/ＥＡＧＥ等地球物理组织 ,在 90年代先后推出了二维Ｍａｒｍｏｕｓｉ模型和三维盐丘模型 ,业已成为勘探地球物理界的标准模型 .显然 ,这两个模型是基于欧美及中东国家的地质背景 ,反映海相沉积特点的 .为促进陆相油储地球物理学的发展 ,满足我国油田对方法技术发展的需求 ,使检验地震处理方法的地质模型能够体现我国陆相沉积的具体特点 ,经国家自然科学基金会重大项目“陆相油储地球…     

合成地震动方法用于研究强地震动长周期特性的探讨

合成地震动一直是地震学研究中一个非常跃的领域。针对２长周期结构物抗震设计缺少宽频带强震记录的现状,利用“反射率法”和“围道积分法”等合成地震动方法对地震动长周期特性进行了探讨。结果表明：合成地震动方法是研究地震动长周特性的一个有效方法;在地震动长周期成份中,面波起着重要作用。因此长周期结构物的抗震设计必须考虑面波的影响。     

我国震例前兆异常统计特征和应用研究

进行了我国大陆80多个震例(1987～1999年)的前兆异常项数统计, 研究了强震前流体、 形变和电磁三大观测类别的前兆异常项的时空变化属性和综合特征。 着重讨论这3类前兆异常从中期向短临过渡的标记、 可能的场、 源兆、 前兆变化的相关性、 分布的不均匀性及与地震活动的一致性。 在此基础上, 提出综合判定指标并用概率增益的方法对我国大陆强震预测作了一定的应用研究。