Estimation of seismic spectral acceleration in Peninsular India

Peninsular India (PI), which lies south of 24°N latitude, has experienced several devastating earthquakes in the past. However, very few strong motion records are available for developing attenuation relations for ground acceleration, required by engineers to arrive at rational design response spectra for construction sites and cities in PI. Based on a well-known seismological model, the present paper statistically simulates ground motion in PI to arrive at an empirical relation for estimating 5% damped response spectra, as a function of magnitude and source to site distance, covering bedrock and soil conditions. The standard error in the proposed relationship is reported as a function of the frequency, for further use of the results in probabilistic seismic hazard analysis.     

Apparent motions of quasars due to microlensing

The effect of weak microlensing on the apparent velocities of extragalactic sources is considered; in particular, the apparent motions of sources from the ICRF list are discussed. We expect from two to seven cases of apparent motions of extragalactic sources due to weak microlensing by stars or dark bodies in our Galaxy to be detected over the next 30 years.     

阵列式位移计测试技术在土-结构体系振动台模型试验中的应用

阵列式位移计（SAA）是一种基于微电子机械系统测试原理的测试加速度和位移的传感器,该方法具有精度高、可重复利用、自动实时采集等特点。介绍了SAA测试技术首次在成层土中桩基与复合桩基大型振动台模型试验中的应用,研究了桩基、复合地基及模型地基土体系的地震位移响应。试验结果表明：SAA可全面、直观地测试桩体及土体在地震动荷载下的加速度以及变形反应规律;测试数据发现小震作用下,地基土与桩身位移协调;随地震作用加大,地基土与桩身位移差异增大;地基土中软土夹层的存在对地基土的水平位移影响较大。     

Estimation of the rock mass deformation modulus using a rock classification system

It is often difficult to directly obtain specific design parameters of interest. In these situations, estimation based on empirical correlations is an alternative. The deformation modulus of a rock mass, which is important to know for engineering projects, is measured by in situ tests, such as plate bearing, flat jack, pressure chamber, borehole jacking and dilatometer tests. Nevertheless, these in situ tests are expensive, time consuming and sometimes even impossible. Many attempts have been made to estimate the E modulus using easy-to-obtain parameters of a rock mass. This paper reviews previous studies and the equations that have been developed. In addition, this study presents a new relation developed using a database of 82 dilatometer test results gathered from two dam sites and a tunnel site. Statistical analyses were performed to correlate accessible rock parameters with measured E modulus values from in situ tests. Knowing that discontinuity characteristics and the strength of rock materials are the most important contributors to rock deformability, the focus was on identifying parameters that are affected by the mentioned properties. Among the tested parameters, RMR (Rock Mass Rating) showed the best correlation with the E modulus. Statistical analyses resulted in a new empirical equation that has an acceptable estimation ability.     

Magnitude calibrating functions for a multidimensional homogeneous system of reference stations

Calibrating functions play a substantial role in the determination of earthquake magnitudes. Their shape and character is closely connected with the internal structure of the Earth, the distribution of velocities and attenuation of seismic waves in the Earth's body. These facts have been considered during the establishment of the Eurasian Homogeneous Magnitude System (EuHMS). The paper summarizes the procedures used for constructing the new complete set of calibrating functions for body and surface waves (vertical and horizontal components of P, S and L waves from medium period instruments, and vertical component of P waves from short period instruments).The calibrating functions were derived in the distance range between 20° and 100°, being based on several thousands of homogeneous observations for each wave type. The application of a HMS gives a possibility to derive the magnitude calibrating functions with a considerable degree of reliability due to the method of simultaneous optimization of the calibrating functions and the systems of station corrections. The magnitude calibrating functions for EuHMS represent the first complete set of calibrating functions, which are derived by the same standard method and initial observational material. A comparison with the existing calibrating functions shows that the application of σ and Q functions, presently used in the seismological practice for magnitude determinations, may lead to errors exceeding of magnitude unit at certain epicentral distances, specific for each wave type. It appears that the internationally recommended Q functions are not admissible for magnitude determinations from short-period P waves.     

Physical origins for variations in the apparent positions of quasars

The physical origins of the apparent motion of radio sources in the ICRF are considered. The sources can be divided into four groups, according to the characteristics of their motion. Here, we consider the model for the motion of the first group of sources—those displaying uniform linear motion. Since the apparent speeds of the radio sources are close to, and sometimes exceeding, the speed of light, it is natural to suppose that these sources are relativistic jets or plasma clouds moving with speeds close to the speed of light. Uniform linear motion can be explained by a model invoking precession of the jet. We consider the physical characteristics of a number of selected sources of the ICRF in the proposed model.     

Principles for selecting a list of reference radio sources for a celestial coordinate system

Time series of the coordinates of radio sources defining the celestial coordinate frame are analyzed. Methods for selecting such sources so as to enhance the stability of the frame are considered. Some of these sources, including so-called “defining” sources, demonstrate significant proper motions. Since the stability of the celestial coordinate frame is determined by an absence of global rotation relative to the defining sources (no net rotation), variation in their coordinates will lead to a rotation of the axes of the celestial coordinate frame. The parameters of this rotation are calculated for two physical models for the motions of extragalactic radio sources. The motions displayed by the first group of sources are linear and uniform. Since the apparent speeds of radio sources are often close to, and sometimes exceed, the speed of light, it is supposed that such radio sources have relativistic jets or plasma clouds that move with speeds roughly equal to the speed of light. The observed uniform, linear motion can then be explained by precession of the jet. The second group of sources display non-linear motions, interpreted as a manifestation of the acceleration of matter by the jet. It is assumed that a cloud of particles that moves into the path of the jet is accelerated to relativistic speeds by the jet. A list of sources that should form a very stable coordinate system for several decades into the future is composed based on these two models.     

Radiant flux as a guide to relative seismic efficiency

The parameters “radiant flux” (energy radiated per unit area of an earthquake fault in unit time) and “radiant flux per unit displacement” reflect the power dissipated on a fault during slip. Values for moderate-to-large earthquakes range over two orders of magnitude, implying considerable variations in seismic efficiency, even for events of similar magnitude occurring on faults of the same type.     

An algorithm for finding the position of a point relative to a fixed polygonal boundary

This article describes a method that determines the position of a point relative to a fixed boundary. Its advantage over the other existing algorithms described below is that in most cases it is necessary that only part of the algorithm be executed to determine the position of the point. A possible inconvenience of using this algorithm is that the contour boundary has to be entered as data. For problems where the boundary often changes the algorithm is not suitable in its present form. The applications envisaged here are to cases where the position of a very large number of points have to be determined relative to one fixed polygonal boundary whose shape is known in advance, for example, blanking out of contours in automatic contouring, or selecting drill holes which lie in the particular part of a mineral deposit.     

Estimation of relative depth of burial using vitrinite reflectance: Implications for a sedimentary basin formation by basement tilting

The kinetics of coalification are still debatable; the role of time has not been conclusively assigned. If accepting the importance of time, we have not reached consensus in formulation of the kinetics.Here we show that estimation of burial depth is possible under some conditions using vitrinite reflectance neither with computation of a specific kinetic equation of organic metamorphism nor with postulating plausible geothermal gradients of the past. The present technique is based only on empirical linear relations between vitrinite reflectance and burial depth, and is demonstrated to be effective for investigation of syn-depositional tectonics. The authors applied the technique to Miocene coals of the Chichibu Basin, Central Japan, and this study indicates that the sedimentary basin was formed by tilting of the basement rocks.     

Estimation of gravity field parameters by a multiple input/output system

The recovery of gravity field parameters using various heterogeneous data is performed according to the input/output system theory (IOST) method. The combination of different data sets is carried out by the application of a multiple input — multiple output system. The theory of the algorithm is presented and some conclusions on the assumptions made for the data properties are drawn. Comparisons between a combined system and individual uncorrelated systems are made and the proper use of the data sets in each case is discussed. Finally, an application is presented, where input data, such as shipborne gravity anomalies and sea surface heights (SSHs) derived from different satellite missions, are optimally combined in order to estimate marine geoid heights and sea surface topography (SST).     

Possibilities for studying microlensing of distant quasars using the RADIOASTRON space interferometer

Gravitational lensing is a powerful tool for studies of the distribution of matter (including dark matter) in the Universe. The characteristic angular separation of images and characteristic variability time scale depend on the characteristic masses of the gravitational lenses. The construction of the RADIOASTRON space interferometer in the coming years will provide qualitatively new conditions for investigations of microlensing of distant quasars in the radio, since it will become possible not only to resolve individual microimages of these quasars, but also to observe astrometric microlensing (i.e., the shift of an image of a distant quasar, sometimes called weak microlensing). Astrometric microlensing by compact objects in the Galactic halo is not a very significant effect for the RADIOASTRON interferometer, since the probability of such events is low and the characteristic time scales involved appreciably exceed the proposed operational lifetime of the interferometer.     

Estimation of the Primary Magma Compositions of an Igneous Rock Series Petrogenetically Associated with Fractional Crystallization with Special Reference to Element Abundance Relationships

A primary magma not only represents the starting point of a fractional crystallization process, but also is the product of an equilibrium or fractional partial melting process in a mantle.Element abundance relationships in the primary magma obey both law of power function for fractional crystallization and the law of fractional linear function for equilibrium partial melting .Based on this double nature of the primary magma, the authors advanced a principle to restore the primary magma composition from that of an igneous rock series with petrogenesis of fractional crystallization and put forward an approach of estimating the element abundance of the primary magma, exempli-fied by the rar-earth elements in the Andes volcanic rock series.     

Possible mechanisms for the polarization of the radiation of Active Galactic Nuclei and quasars

Two mechanisms for the formation of polarized radiation in Active Galactic Nuclei and quasars are considered-synchrotron radiation from a jet and the emergence of radiation from a magnetized, optically thick accretion disk (the Milne problem in a magnetized atmosphere). These mechanisms are applied to the polarization of objects studied in [1]. We have shown that the polarization of some sources cannot be explained as synchrotron radiation. The second mechanism is more general and, in principle, can be applied to the polarized radiation of all the sources in [1].     

Locating a point on a spherical surface relative to a spherical polygon of arbitrary shape

An algorithm for determining if any given point,P, on the surface of a sphere is located inside, outside, or along the border of an arbitrary spherical polygon,S, is described. The polygon is described by specifying coordinates of its vertices, and coordinates of some pointX which is known to lie withinS. The algorithm is based on the principle that an arc joiningX andP will cross the border ofS an odd number of times ifP lies outsideS, and an even number of times ifP lies withinS. The algorithm has been implemented as a set of FORTRAN subroutines, and a listing is provided. The algorithm and subroutine package can be used with spherical polygons containing holes, or with composited spherical polygons.     

Evaluation of spatial variation of peak horizontal acceleration and spectral acceleration for south India: a probabilistic approach

In this work, an attempt has been made to evaluate the spatial variation of peak horizontal acceleration (PHA) and spectral acceleration (SA) values at rock level for south India based on the probabilistic seismic hazard analysis (PSHA). These values were estimated by considering the uncertainties involved in magnitude, hypocentral distance and attenuation of seismic waves. Different models were used for the hazard evaluation, and they were combined together using a logic tree approach. For evaluating the seismic hazard, the study area was divided into small grids of size 0.1° × 0.1°, and the hazard parameters were calculated at the centre of each of these grid cells by considering all the seismic sources within a radius of 300 km. Rock level PHA values and SA at 1 s corresponding to 10% probability of exceedance in 50 years were evaluated for all the grid points. Maps showing the spatial variation of rock level PHA values and SA at 1 s for the entire south India are presented in this paper. To compare the seismic hazard for some of the important cities, the seismic hazard curves and the uniform hazard response spectrum (UHRS) at rock level with 10% probability of exceedance in 50 years are also presented in this work.     

MEMS加速度传感器在矿用随钻轨迹测量系统中的误差校正

矿用随钻轨迹测量系统的工具面向角和倾角通常采用加速度传感器实现测量,然而由于传感器制作工艺、探管机械加工以及装配等因素使得工具面向角和倾角的测量出现误差。为了修正上述系统误差,首先介绍了随钻轨迹测量系统及其工作原理,进而分析了加速度传感器的误差产生,并建立了MEMS加速度传感器的误差模型;提出了一种基于三十六位置的加速度标定方法,并对其进行相应的测试。实验结果表明：建立的加速度误差模型在随钻轨迹测量系统中,倾角精度为0.2°,工具面向角精度为0.2°,且倾角和工具面向角之间相互影响较小,能够满足实际煤矿井下钻探工艺的精度需求。     

Population changes in a growth center region with reference to the Israeli Negev

The aim of this paper is to present a scheme of relative population changes in a geographic-termed growth center region, with reference to a real problem of development as implemented in the Israeli Negev arid zone. The growth process described in the scheme leads to dynamic steady-states which indicate stable structure and stable relationships between the components of the regional system — the growth center and its urban and rural hinterlands. It was found that the relative population growth process in the Negev during the last thirty years is similar to the process determined by the scheme. Furthermore, geo-political changes in the area due to the peace treaty between Egypt and Israel may alter this process and open a new period of regional growth. An additional thrust of this paper is methodological: to introduce and apply the hexagonal diagram to describe and classify processes of relative population growth.