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Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called potential model are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=–0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=–0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes –0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.  相似文献   
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3.
We analyze high sampling waveforms of the initial part of P-wave recorded at the 1800-m-deep borehole seismographs at the Nojima fault from December 1999 to May 2000 to clarify the initial rupture process of microearthquakes. We select 12 events with high S/N, whose magnitudes range from −0.3 to 2.2 and hypocentral distances from 1 to 11 km. We adopt the two different source models by Sato and Hirasawa (1973) and by Sato and Kanamori (1999). The former (model by Sato and Hirasawa (SH model)) generates only a ramp-like onset of velocity pulse. The later (model by Sato and Kanamori (SK model)) is able to generate a weak initial phase that is controlled by a trigger factor and the length of pre-existing crack. We perform the waveform inversion to estimate the optimum source parameters of each model. Waveforms of 5 of the 12 events are clearly reproduced by both SH model and SK model with a large trigger factor and a small length of pre-existing crack. The others are explained by not SH model but only SK model with a small trigger factor and a large length of the pre-existing crack, indicating that the weak initial phase is a nucleation phase and reflects the source process. These seven events satisfy roughly a relation that a large event has a large length of the pre-existing crack; the final crack length is proportional to the length of the pre-existing crack.  相似文献   
4.
The Hokuroku district, extending over 40 × 40 km2 in northern Japan, is known to be dominated by kuroko-type massive sulfide deposits that have a genetic relation to submarine volcanic activity. The deposits are hosted in a specific stratigraphic zone of Miocene volcanic rocks. Because kuroko-type deposits are under exploration in several countries, it is important to integrate the geologic and geochemical data that have been accumulated in the Hokuroku district to characterize the distribution of deposits and produce a map of mineral potential. Thus, we collected data on multiple chemical components from 1917 rock cores at 143 drillhole sites and concentrated on components with relatively large amounts of data, which are SiO2, Al2O3, and Fe2O3 as major elements and Cu, Pb, and Zn as trace elements. Although frequencies of these data can be approximated by normal or lognormal distributions, spatial correlation structures cannot be extracted from the semivariograms of each component nor from the cross-semivariograms between two components of the major or minor elements. To handle such complexity, a spatial method of modeling content distribution, SLANS, is developed by applying a feedforward neural network. The principle of SLANS is to train a network repeatedly to recognize the relation between the data value and the location and lithology of a sample point. One-hundred outputs for each element are obtained by changing the numbers of neurons in a middle layer from 1 to 10 and sample data used for training from 3 to 12, and finally one output is selected based on the estimation precision of the network which is restricted near the target point. After constructing a geologic distribution model from the geological column classified into 25 rock codes, three-dimensional distributions of Cu, Pb, and Zn contents are estimated over the study area. The content models are considered to be valid because high-content zones are located on the known mine sites and the margins of ancient volcanoes or calderas. Some zones are distributed along strikes of major deep-seated fractures in the district.  相似文献   
5.
In addition to spatial distribution of groundwater-flow parameters, aquifer properties of location and shape are also significant for assessing groundwater resources because they strongly affect water flow. We present a selection of geologic data suitable for aquifer analysis, a mathematical method of processing them, and a combination of several maps produced by it. The data used in the analysis are typically obtained by borehole investigation. Our targets are the areas underlain by geologic bodies with different ages and lithologies; the spatial correlation structures of geologic data over the areas tend to change locally. The processing method should be a versatile one that is applicable to areas where geostatistical stationarity is not satisfied. The aquifer analysis consistent with that requirement consists of two steps: the first is the transformation of screen locations, locations of sand and gravel layers, and resistivity by electric logging into indicator values, and the second is three-dimensional interpolation of these using the optimization principle method to produce three kinds of distribution models. A stochastic simulation is also used for modeling the resistivity distribution. The three distribution models are integrated to generate a value for evaluating the possibility of aquifer existence. A case study of an alluvial coastal plain, situated in southwest Japan, describes an aquifer model that contains three permeable layers. Each layer has about 10-m thickness and is lens shaped. To confirm the validity of the model, we have drilled two wells that reached one of the middle and bottom permeable layers, observing the water level change. Low correlation of the temporal changes of levels between the wells indicates that the two layers are hydrologically independent of each other. Additionally, groundwater-flow patterns have been estimated by transforming the simulation model parameter into hydraulic conductivity through a simple function and using a finite difference method for flow analysis. The procedure proposed by this study can be applied to other areas by changing the weights assigned to each geologic and geotechnical factor in the generation of the coefficient for aquifer existence, considering the reliability of each factor and hydrologic properties of study area.  相似文献   
6.
Abstract A water injection experiment was carried out by the scientific drilling program named the 'Nojima Fault Zone Probe' during the two periods 9–13 February and 16–25 March 1997. The pumping pressure at the surface was approximately 4 MPa. The total amount of injected water was 258 m3. The injection was made between depths of 1480 m and 1670 m in the Disaster Prevention Research Institute, Kyoto University (DPRI) 1800 m borehole drilled into the Nojima Fault zone. A seismic observation network was deployed to monitor seismic activity related to the water injections. Seismicity suddenly increased in the region not far from the injection hole 4 or 5 days after the beginning of each water injection. These earthquakes were likely to be induced by the water injections. Most of the earthquakes had magnitudes ranging from −2 to +1. Numerous earthquakes occurred during the first injection, but only one could be reliably located and it was approximately 2 km north of the injection site. Between the two injection periods, earthquakes concentrated in the region approximately 1 km northwest of the injection site. During and after the second injection experiment, earthquakes were located approximately 1.5 km west of the injection site. Those earthquakes were located approximately 3 km or 4 km from the injection point and between 2 km and 4 km in depth. Values of intrinsic permeability of 10−14–10−15 m2 were estimated from the time lapse of the induced seismic activity. The coefficient of friction in the area where the induced earthquakes occurred was estimated to be less than 0.3.  相似文献   
7.
Interplanetary scintillation (IPS) measurements of the solar wind speed for the distance range between 13 and 37 R S were carried out during the solar conjunction of the Nozomi spacecraft in 2000?–?2001 using the X-band radio signal. Two large-aperture antennas were employed in this study, and the baseline between the two antennas was several times longer than the Fresnel scale for the X-band. We successfully detected a positive correlation of IPS from the cross-correlation analysis of received signal data during ingress, and estimated the solar wind speed from the time lag corresponding to the maximum correlation by assuming that the solar wind flows radially. The speed estimates range between 200 and 540?km?s?1 with the majority below 400?km?s?1. We examined the radial variation in the solar wind speed along the same streamline by comparing the Nozomi data with data obtained at larger distances. Here, we used solar wind speed data taken from 327 MHz IPS observations of the Solar-Terrestrial Environment Laboratory (STEL), Nagoya University, and in?situ measurements by the Advanced Composition Explorer (ACE) for the comparison, and we considered the effect of the line-of-sight integration inherent to IPS observations for the comparison. As a result, Nozomi speed data were proven to belong to the slow component of the solar wind. Speed estimates within 30 R S were found to be systematically slower by 10?–?15 % than the terminal speeds, suggesting that the slow solar wind is accelerated between 13 and 30 R S.  相似文献   
8.
An application of a geotechnical database system for primary evaluation of ground-water resources in a sedimentary basin is proposed. The database consists of 1200 borehole logs including geologic columns,in situ test results, ground-water level, water quality data, and resistivity logs. The Kumamoto plain, situated in southwest Japan, is chosen as a study area. The evaluation process consists of two steps: (1) modeling of shapes of water-bearing strata, and (2) modeling of distribution of physical quantity which has some relationship with the porosity of those strata. In step (1), the shapes of upper and/or lower surface of the pyroclastic flow deposits and the andesitic lava were determined, whereas the three-dimensional distribution model of resistivity was constructed from resistivity logging data obtained from 100 boreholes and using the proposed interpolation method in the step (2). An empirical equation between the porosity and the resistivity of the lava was also identified. The integration of two types of model and the empirical equation contributed to an estimate of the total volume of the ground-water under the study area.  相似文献   
9.
One of the factors that determines the suitability of limestone for industrial use and its commercial value is phosphorus (P) content, i.e., the weight percentage of phosphorus contained in small quantities of limestone. Because P content changes locally, geostatistical techniques including semivariogram, ordinary kriging, and conditional indicator sequential simulation were used in this study to identify the spatial correlation of P content and to estimate its three-dimensional distribution in an open-pit mine. The P content data at 43,000 points of five different bench levels were analyzed. It was found that the horizontal semivariograms produced by using the data at the same bench level show anisotropic behavior and are represented by the sum of two spherical models with different ranges and sills. The twelve vertical semivariograms were also constructed from P content in boring cores. After these semivariograms were classified into four types, a multilayered neural network was applied to clarify the horizontal distribution of each one. One of the twelve semivariograms was assigned to an arbitrary grid point in the study area by the criterion that its type is the same as the one estimated at the point and the borehole site producing the semivariogram is the nearest to the point. With this technique, ordinary kriging combined with the semivariogram of borehole data provided a proper estimation of P content in the depth direction.  相似文献   
10.
Thirteen synoptic maps of expansion rate of the coronal magnetic field (CMF; RBR) calculated by the so-called ‘potential model’ are constructed for 13 Carrington rotations from the maximum phase of solar activity cycle 22 through the maximum phase of cycle 23. Similar 13 synoptic maps of solar wind speed (SWS) estimated by interplanetary scintillation observations are constructed for the same 13 Carrington rotations as the ones for the RBR. The correlation diagrams between the RBR and the SWS are plotted with the data of these 13 synoptic maps. It is found that the correlation is negative and high in this time period. It is further found that the linear correlation is improved if the data are classified into two groups by the magnitude of radial component of photospheric magnetic field, |Bphor|; group 1, 0.0 G ≦ |Brpho| < 17.8 G and group 2, 17.8 G ≦ |Brpho|. There exists a strong negative correlation between the RBR and the SWS for the group 1 in contrast with a weak negative correlation for the group 2. Group 1 has a double peak in the density distribution of data points in the correlation diagram; a sharp peak for high-speed solar wind and a low peak for low-speed solar wind. These two peaks are located just on the axis of maximum variance of data points in the correlation diagram. This result suggests that the solar wind consists of two major components and both the high-speed and the low-speed winds emanating from weak photospheric magnetic regions are accelerated by the same mechanism in the course of solar activity cycle. It is also pointed out that the SWS can be estimated by the RBR of group 1 with an empirical formula obtained in this paper during the entire solar activity cycle.  相似文献   
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