The Study of Medium- and Short-term Prediction for Artux Earthquake (M_S=6.9) and Usunan Earthquake (M_S=5.8)

In this paper, the process of medium- and short-term prediction (submitted in special cards) of the Artux earthquake (MS=6.9) and the Usurian earthquake (MS=5.8) in Xinjiang area, is introduced. The imminent seismic risk regions are judged based on long- and medium-term seismic risk regions and annual seismic risk regions determined by national seismologic analysis, combined with large seismic situation analysis. We trace and analyze the seismic situation in large areas, and judge principal risk regions or belts of seismic activity in a year, by integrating the large area's seismicity with geodetic deformation evolutional characteristics. As much as possible using information, we study synthetically observational information for long-medium- and short-term (time domain) and large-medium -small dimensions (space domain), and approach the forecast region of forthcoming earthquakes from the large to small magnitude. A better effect has been obtained. Some questions about earthquake prediction are discussed.     

青藏高原印度板块向欧亚大陆俯冲速率的研究——GPS观测资料的反演结果

利用近年来中外几个研究单位在青藏高原的GPS观测结果，根据印度板块向欧亚大陆 俯冲模型，采用二层弹性自重半空间内断层运动的位错模型，对印度板块向欧亚大陆俯冲的 速率进行了反演，给出了在大地测量观测结果约束下的现今印度板块向欧亚大陆俯冲的速率 . 反演结果表明，现今印度板块约以8.1°的倾角、21.8 mm/a的速率向欧亚大陆俯冲. 本文 结果与从地质推断的在过去2～３Ma时期内，印度板块向欧亚大陆俯冲速率平均为18mm/a,有 较好的一致性,表明在较长时间内，印度板块向欧亚大陆俯冲的速率仍然是稳定的.     

Utilization of high resolution satellite gravity over the Carlsberg Ridge

The Carlsberg Ridge lies between the equator and the Owen fracture zone. It is the most prominent mid-ocean ridge segment of the western Indian Ocean, which contains a number of earthquake epicenters. Satellite altimetry can be used to infer subsurface geological structures analogous to gravity anomaly maps generated through ship-borne survey. In this study, free-air gravity and its 3D image have been generated over the Carlsberg Ridge using a very high resolution data base, as obtained from Geosat GM, ERS-1, Seasat and TOPEX/POSEIDON altimeter data. As observed in this study, the Carlsberg Ridge shows a slow spreading characteristic with a deep and wide graben (average width ∼15 km). The transform fault spacing confirms variable slow to intermediate characteristics with first and second order discontinuities. The isostatically compensated region of the Carlsberg Ridge could be demarcated with near zero contour values in the free-air gravity anomaly images over and along the Carlsberg Ridge axes and over most of the fracture zone patterns. Few profiles have been generated across the Carlsberg Ridge and the characteristics of slow/intermediate spreading ridge of various orders of discontinuity could be identified. It has also been observed in zero contour image as well as in the characteristics of valley patterns along the ridge from NW to SE that different spreading rates, from slow to intermediate, are occurring in different parts of the Carlsberg ridge. It maintains the morphology of a slow spreading ridge in the NW, where the wide and deep axial valley (∼1.5–3 km) also implies the pattern of a slow spreading ridge. However, a change in the morphology/depth of the axial valley from NW to SE indicates the nature of the Carlsberg Ridge as a slow to intermediate spreading ridge. For the prevailing security restrictions, lat./lon. coordinates have been omitted in few images.     

中西地图学史的比较研究

本文提出了中西制图史年表。17世纪前中国地图学受日本、朝鲜等国影响大,此后受西方影响较大。中国制图中心迁移与政治中心一致;而西方受宗教的影响和经济发展的制约。中西方交流之前各以自己特有的方式发展,形成了两种不同的制图系统。最后提出了中国制图学发展没有取得较大突破的原因。     

Analysis of crustal deformation in Luzon, Philippines using geodetic observations and earthquake focal mechanisms

We utilize regional GPS velocities from Luzon, Philippines, with focal mechanism data from the Harvard Centroid Moment Tensor (CMT) Catalog, to constrain tectonic deformation in the complex plate boundary zone between the Philippine Sea Plate and Eurasia (the Sundaland block). Processed satellite imagery and digital elevation models are used with existing gravity anomaly, seismicity, and geologic maps to define a suite of six elastic blocks. Geodetic and focal mechanism data are inverted simultaneously to estimate plate rotations and fault-locking parameters for each of the tectonic blocks and faults comprising Luzon. Major tectonic structures that were found to absorb the plate convergence include the Manila Trench (20–100 mm yr^− 1) and East Luzon Trough ( 9–15 mm yr^− 1)/Philippine Trench ( 29–34 mm yr^− 1), which accommodate eastward and westward subduction beneath Luzon, respectively; the left-lateral strike-slip Philippine Fault ( 20–40 mm yr^− 1), and its northward extensions, the Northern Cordillera Fault ( 17–37 mm yr^− 1 transtension), and the Digdig Fault ( 17–27 mm yr^− 1 transpression). The Macolod Corridor, a zone of active volcanism, crustal thinning, extension, and extensive normal and strike-slip faulting in southwestern Luzon, is associated with left-lateral, transtensional slip of  5–10 mm yr^− 1. The Marikina Fault, which separates the Central Luzon block from the Southwestern Luzon block, reveals  10–12 mm yr^− 1 of left-lateral transpression. Our analysis suggests that much of the Philippine Fault and associated splays are locked to partly coupled, while the Manila and Philippine trenches appear to be poorly coupled. Luzon is best characterized as a tectonically active plate boundary zone, comprising six mobile elastic tectonic blocks between two active subduction zones. The Philippine Fault and associated intra-arc faults accommodate much of the trench-parallel component of relative plate motion.     

铀矿地质成果数据2000国家大地坐标系转换方法研究

通过对铀矿项目地质成果数据中的空间数据进行分析,把数量庞大的数据分为单点空间数据和图形空间数据两类。在EXCEL软件平台下,使用VBA编写空间数据平面四参数程序,实现四参数模型计算和所有单点坐标的2000国家坐标批量转换。又由于90%的铀矿地质成果图采用MapGIS格式,故采用EXCEL结合VBA在MapGIS二次开发平台上编写程序,实现对MapGIS格式图件的2000国家坐标系的批量转换。选择鄂尔多斯市巴音青格利铀矿地质普查项目进行空间数据2000国家大地坐标的转换,并对结果进行精度分析。结果表明:此方法在生产中精度可靠且容易操作,可以快速准确地完成铀矿地质资料空间数据的2000国家坐标系转换,值得在其他铀矿勘查地区推广。     

Determination of the boundary values for the Stokes–Helmert problem

 The definition of the mean Helmert anomaly is reviewed and the theoretically correct procedure for computing this quantity on the Earth's surface and on the Helmert co-geoid is suggested. This includes a discussion of the role of the direct topographical and atmospherical effects, primary and secondary indirect topographical and atmospherical effects, ellipsoidal corrections to the gravity anomaly, its downward continuation and other effects. For the rigorous derivations it was found necessary to treat the gravity anomaly systematically as a point function, defined by means of the fundamental gravimetric equation. It is this treatment that allows one to formulate the corrections necessary for computing the `one-centimetre geoid'. Compared to the standard treatment, it is shown that a `correction for the quasigeoid-to-geoid separation', amounting to about 3 cm for our area of interest, has to be considered. It is also shown that the `secondary indirect effect' has to be evaluated at the topography rather than at the geoid level. This results in another difference of the order of several centimetres in the area of interest. An approach is then proposed for determining the mean Helmert anomalies from gravity data observed on the Earth's surface. This approach is based on the widely-held belief that complete Bouguer anomalies are generally fairly smooth and thus particularly useful for interpolation, approximation and averaging. Numerical results from the Canadian Rocky Mountains for all the corrections as well as the downward continuation are shown. Received: 9 March 1998 / Accepted: 16 November 1998     

用于影像几何纠正的图形图像控制点

几何纠正是摄影测量中的一个基本的数据处理过程。在常规的方法中,往往遇到找不到控制点的情况,这时的几何纠正就变得非常困难。为了解决这种问题,作者提出了一个新的概念———图形图像控制点,并从它的原理和使用方法两个方面加以探讨。通过把图形图像控制点与原始影像叠加,可以很方便地获取几何纠正所需要的转换矩阵     

大地测量观测和相对海平面联合约束的冰川均衡调整模型

利用大地测量和历史相对海平面变化数据,结合地震剪切波层析模型,联合确定了新的末次冰期冰川均衡调整（GIA）模型,其中地幔黏滞度不仅沿径向而且沿横向变化.研究思路是,先尝试性地选择比例系数β,利用与地震剪切波速异常的线性关系,计算地幔黏滞度横向扰动,并与横向均匀的黏滞度参考模型叠加给出3D地幔黏滞度模型;再利用耦合拉普拉斯方程的有限元法算法进行GIA预测;然后,重复该过程,直到预测与观测之间的吻合满意为止.主要结论有：（1）给出了横向非均匀的地幔黏滞度模型（RF3L20(β=0.4)）,发现了黏滞度显著的横向非均匀性和其对GIA预测的显著影响,指出横向非均匀不完全是由热效应引起的,可能还与化学组分等其他因素有关,该模型可用于地幔动力学研究.（2）给出了全球现今多种GIA预测速率,可为板块运动、陆地水储量、海水质量变化和冰川冰雪质量非平衡监测提供重要的改正.     

大地测量基本常数--对"永久性潮汐与大地测量基准"一文的一个注记

本文是对“永久性潮汐与大地测量基准＾「１」一文的补充和注记。文中将ＩＡＧ给定的大地测量基本常数ａ,Ｊ２、ＧＭ和ω的近期所测定的最新值作了介绍,并对它们与永久性潮汐有关的数值作了分类（无潮汐值、平均潮汐值和零潮汐值）,以使有关方面采用。