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111.
112.
A set of acceleration source spectra is constructed using the observed parameters of the specific barrier model of Papageorgiou and Aki. The spectra show a significant departure from the 2-model at the high frequency range. Specifically, the high frequency spectral amplitudes of seismic excitation are higher as compared to the level predicted by the 2-model. This is also supported by other observational evidence. The high frequency amplitudes of acceleration scale proportionally to the square root of the rupture areaS, to the rupture spreading velocityv, and to the local strain drop (/) (=strain drop in between barriers). The local strain drop in between barriers is not related in a simple way to the global strain drop, which is the strain drop estimated by assuming that it is uniform over the entire rupture area. Consequently, the similarity law does not apply. Using the source spectra which we constructed, we derive expressions for high frequency amplitudes of acceleration such asa
rms anda
max. Close to the fault both are independent of fault dimensions and scale as (/µ)(f)1/2, while away from the fault plane they scale asW
1/2(/µ)(f)1/2, whereW is the width of the fault and f is the effective bandwidth of the spectra. 相似文献
113.
Magmatic intrusions can trigger thin-skinned compression of the adjacent sedimentary cover by three processes: (a) gravity gliding away from the topographic dome resulting from the ascending magma; (b) fluid push from the rear resulting from forceful intrusion then lateral spreading of the magma; and (c) increased loading by volcanic accumulation. The applicability of the first two mechanisms, gravity gliding and fluid push, was tested using dynamically scaled experiments. Model results help to elucidate the kinematics and structural evolution of thrusts and folds formed by such processes and determine which geological parameters control the deformation style. The results show that the presence of a weak layer within the sedimentary overburden is essential to form thrust and fold belts around the intrusion. Experiments suggest that although gravity gliding can dominate the early stages of deformation, most of the deformation is caused by lateral spreading of the fluid magma pushing the adjacent sedimentary rocks. Models also suggest that true laccoliths can form only if the sedimentary section comprises a basal low-viscosity stratum. Comparison with natural examples allows the evaluation of the applicability of experimental results. 相似文献
114.
The paper reveals that the variations in parameters like u*, the scaling velocity and θ*. The scaling tempera-ture during the various phases of monsoon might be linked with subsynoptic features. The rise in u* is mainly connected with the presence of lower tropospheric cyclonic vorticity over a subsynoptic scale of the site. However the variations in θ* is mainly linked with the various phases of monsoon and θ* shows a sharp rise in presence of low level convective cloud.Besides the correlation studies of u and u*, θv and θv* , θv-θv0 and θv* are undertaken. The correlation be?tween θv and θv* is poor. In other two cases correlations are good. Besides u/u* , has shown good coefficient of variation values within the ζ range. 相似文献
115.
城市居民认知距离透视认知变形 ——-以北京市为例 总被引:1,自引:0,他引:1
对距离的认知是人类建立认知空间框架的重要基础。本文在相关研究的基础上, 对认知距离的特点进行了分析, 提出从数量认知距离与实际认知距离两种分析角度来分析这一概念。通过分别利用定义一元线性回归, 与 采用多维标度法(MDS)及二维回归(BR), 对认知距离的标量变形和向量变形进行定量分析。在此基础上, 以北京市 为例, 对北京市居民进行抽样调查。通过认知心理学实验的方式, 令被试估计城市主要地标两两之间的距离。对实 验结果分别将上述方法应用于计算北京市居民在标量变形和向量变形的定量化表示, 并进一步通过方差分析 (ANOVA)讨论了影响北京市居民对城市距离认知变形的因素, 包括年龄、居住地区等。 相似文献
116.
117.
118.
Scaling vesicle distributions and volcanic eruptions 总被引:1,自引:1,他引:0
Models of coalescence-decompressive expansion of the later stages of bubble growth predict that for diverse types of volcanic products the vesicle number densities (n(V)) are of the scaling form
where V is the volume of the vesicles and B3 the 3-dimensional scaling (power law) exponent. We analyze cross sections of 9 pumice samples showing that over the range of bubble sizes from 10 m to 3 cm, they are well fit with B30.85. We show that to within experimental error, this exponent is the same as that reported in the literature for basaltic lavas, and other volcanic products. The importance of the scaling of vesicle distributions is highlighted by the observation that they are particularly effective at packing bubbles allowing very high vesicularities to be reached before the critical percolation threshold, a process which—for highly stressed magmas—would trigger explosion. In this way the scaling of the bubble distributions allows them to be key actors in determining the rheological properties and in eruption dynamics.Editorial responsibility: D. Dingwell 相似文献
119.
The paper describes the unified scaling theory for distribution functions of temporal and spatial characteristics in seismology. It is based on the scaling of seismological characteristics calculated for various energy–spatial–temporal intervals. The common mathematical methods for the scaling of distribution functions are developed. The means to test possibility of such scaling are found as well. The relationship between the unified scaling theory and other present scaling approaches is determined. The theory is applied to two characteristics of different seismoactive regions. The first characteristic is the waiting time between earthquakes ΔT, the second one is a new space parameter ΔDmin, which is the minimum distance of a current seismic event to the nearest (in space) neighbor in an energy–spatial–temporal interval. The distribution of the characteristics ΔT and ΔDmin allows estimating the time interval to the next earthquake and the distance of the following earthquake from previous earthquakes. Thus, these characteristics are very important for seismic hazard estimations. Scaling of distributions functions is proven to be successful for ΔDmin in all energy–spatial–temporal intervals and for ΔT with variations of energy/magnitude range. The distribution function of ΔT for various time domains was stable in only 60% of the cases, and near to unstable for spatial variations. 相似文献