A hypothesis for the seismogenesis of a double seismic zone

The seismogenesis of a double seismic zone, in particular the lower layer of a double seismic zone, has not been adequately explained in the literature. On the basis of seismic data and geothermal structures along three well-studied cross-sections in the Kuril-Kamchatka and Japan subduction zones, we investigate the temperature/pressure conditions associated with seismogenic structures of the double seismic zones. the corresponding T/P loci seem to suggest that earthquakes observed in the lower layer and in the lower part (below approximately 130 ± 20 km) of the top layer of a double seismic zone were caused by metastable phase transition-a mechanism similar to that responsible for deep-focus earthquakes only at lower temperature/pressure conditions. Under this hypothesis, the wedge-shaped configuration of a double seismic zone is interpreted to represent the loci of the kinetic boundary of the phase transition. According to theoretical/experimental studies and the constraints imposed by our observations, a likely candidate for such a phase transition is the metastable Al-rich enstatite decomposing into the assemblage of Al-poor enstatite plus garnet. Earthquakes in the upper part of the top layer were most probably due to conventional mechanisms such as dehydration of subducted materials and/or facies change from basalt to eclogite. That the top layer involves more than one seismogenic mechanism is also implied by the distinct behaviour of seismicity in the vicinity of 130 ± 20 km. Because the presence of deviatoric stress is critical to the reaction rate of a metastable phase transition, it is inferred that single seismic zones are also caused by the same mechanisms, except that the implicit layer of a supposed double seismic zone is missing, due to the insufficient amount of appropriate metastable minerals or to the lack of appropriate deviatoric stresses in the source region.     

On the distribution of flood volume in partial duration series analysis of flood phenomena

A methodology based on the theory of stochastic processes is applied to the analysis of floods. The approach will be based on some results of the theory of extreme values over a threshold. In this paper, we focus on the estimation of the distribution of the flood volume in partial duration series analysis of flood phenomena, by using a bivariate exponential distribution of discharge exceedances and durations over a base level.     

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百色双套自动气象站雷击故障维修的方法

通过对百色双套自动气象站遇到历史罕见的强雷暴袭击出现故障维修,摸索出了检修双套新型自动站的通信、电源供应、主机HY3000、接口RS232、分采仪器等模块的方法,供同行借鉴.     

应用单历元模糊度算法解决实时GPS水汽探测技术中模糊度问题

首先简要介绍实时水汽探测技术的原理,然后采用详细的推算过程将求水汽量转化为求宽巷模糊度的问题,并利用双频P码求出宽巷模糊度。运用实例模拟分析双频P码求宽巷模糊度的精度,解释宽巷模糊度的精度随卫星高度角变化的原因。     

Coupling mechanisms in double sandbar systems. Part 2: impact on alongshore variability of inner‐bar rip channels

Double sandbar systems are common morphological features along sandy, wave‐dominated, micro‐ to meso‐tidal coastlines. In the companion paper, we demonstrated how various alongshore inner‐bar rip‐channel patterns can develop through morphological coupling to an alongshore‐variable outer bar. The simulated coupling patterns are, however, scarcely observed in the field. Instead, inner‐bar rip channels more often possess remarkably smaller and more variable alongshore length scales, suggesting that coupling mechanisms do not play a substantial role in the overall double‐sandbar dynamics. Here we use a numerical model to show that the relative importance of self‐organization and morphological coupling changes in favour of the latter with an increase in waterdepth variability along the outer‐bar crest. Furthermore, we find that the typical alongshore variability in inner‐bar rip‐channel scale is indicative of a mixture of self‐organization and morphological coupling rather than self‐organization alone. Morphological coupling may thus be more important to understanding and predicting the evolution of inner‐bar rip channels than previously envisaged. Copyright © 2010 John Wiley and Sons, Ltd.     

基于ArcGIS与Python的气候评价工具箱的实现与应用

在研究和梳理气候评价技术方法和路线的基础上,利用ArcGIS与Python语言二次开发了一套气候评价工具箱,并以榆林市为例对该工具箱的实用性进行了验证.结果显示,该工具箱能够快速准确地辅助规划人员进行气候评价工作,大大提高了国土空间规划双评价的工作效率.     

利用双向缓冲区算法综合海图岛屿

阐述了岛屿综合的内容和原则。介绍了双向缓冲区算法的概念并给出了双向缓冲区算法的定义,研究并证明了双向缓冲区算法的特性。分析了利用双向缓冲区算法综合海图岛屿的原理,并通过实验验证利用双向缓冲区算法综合海图岛屿具有较好的效果。     

规则格网上双方向性插值DEM精度研究

简要介绍双方向性插值方法的原理,并以线性插值和三次插值过程中的误差传播为基础,利用误差传播定律,推导出双方向性插值方法生成的DEM曲面平均高程误差值,并对线性插值和三次插值公式本身的精度进行分析。