Study of Distal Pyroclastic-flow Stratum from Tianchi Volcano in 1215 (±15) Eruption: Pyroclastic-flow Over Water

In this paper,we describe three strata at the distal part of the pyroclastic-flow from the Tianchi volcano in 1215(±15) eruption.One of the strata with crosslayers that are different from typical pyroclastic-flow strata may come from a ground-surge.The grain-size and scanning electron microscopy(SEM) analysis was performed to study the origin of the pyroclastic-flow.Characteristics of grain-size distribution show that it is similar with the ash cloud.Through the SEM analyses,we found some quench structures with less damage on the surfaces of the vitric pumices.These phenomena indicate that there has been hydration in the transportation processes at the distal of pyroclastic-flow.It has partly changed the transportation mechanism of pyroclastic-flow,which transitions form dense flow to diluted flow.This paper develops a new distal pyroclastic-flow model in the Tianchi volcano that can be divided into three stages,i.e.the quench stage,expanding stage and depositing stage.     

Stages in the Magura Basin: a case study of the Polish sector (Western Carpathians)

The Magura Basin domain developed in its initial stage as a Jurassic-Early Cretaceous rifted passive margin that faced the eastern parts of the oceanic Alpine Tethys. In the pre- and syn-orogenic evolution of the Magura Basin the following prominent periods can be distinguished: Middle Jurassic-Early Cretaceous syn-rift opening of basins (1) followed by Early Cretaceous post-rift thermal subsidence (2), latest Cretaceous–Paleocene syn-collisional inversion (3), Late Paleocene to Middle Eocene flexural subsidence (4) and Late Eocene - Early Miocene synorogenic closing of the basin (5). The driving forces of tectonic subsidence of the basin were syn-rift and thermal post-rift processes, as well as tectonic loads related to the emplacement of accretionary wedge. This process was initiated at the end of the Paleocene at the Pieniny Klippen Belt (PKB)/Magura Basin boundary and was completed during Late Oligocene in the northern part of the Magura Basin. During Early Miocene the Magura Basin was finally folded, thrusted and uplifted as the Magura Nappe.     

四川盆地西缘晚新生代大邑砾岩的物源及其成因：来自重矿物和孢粉的证据

新生代早期印度与欧亚板块的俯冲碰撞造就了巍峨高耸的青藏高原.然而,在其相邻的四川盆地,伴随青藏高原强烈隆升所堆积的碎屑沉积物,最老仅能追索到晚新生代的大邑砾岩.因此,解读广泛发育于四川盆地西缘的大邑砾岩成因对获取青藏高原及其周缘古环境信息及理解相关的构造演化过程具有重要意义.本文报告了对三个典型大邑砾岩剖面样品的重矿物和孢粉组合研究结果,试图从大邑砾岩的物源区和沉积环境来解读大邑砾岩的成因.大邑砾岩中重矿物种类繁多,表明相应物源区具有多种岩石类型.除极不稳定矿物外,大邑砾岩新鲜剖面样品的重矿物组合与现代岷江沉积极其相似,表明大邑砾岩是经由岷江通道输送到四川盆地的;富含石榴子石等远源矿物表明当时的古岷江已切穿龙门山,深入到松潘-甘孜褶皱带内.孢粉分析显示孢粉含量极低,为0.2粒/克,孢粉类型以高山黯针叶林成分为主,混有少量落叶阔叶林和草本植物花粉,显示了高寒的环境.结合已有的年代学结果,本文认为大邑砾岩是形成于2.0Ma的冰水沉积物,其形成反映了青藏高原第四纪早期的寒冷环境.     

Bootstrap Pettitt test for detecting change points in hydroclimatological data: case study of Itaipu Hydroelectric Plant,Brazil

ABSTRACT

The Pettitt test is widely used in climate change and hydrological analyses. However, studies show difficulties of this test in detecting change points, especially in small samples. This study presents a bootstrap application of the Pettitt test, and compares it numerically with the classical Pettitt test by an extensive Monte Carlo simulation. The proposed test outperforms the classical test in all simulated scenarios. An application of the tests is conducted on the historical series of naturalized flows of the Itaipu Hydroelectric Plant in Brazil, for which several studies have shown a change point in the 1970s. When the series is split into shorter sub-series, to simulate actual situations of small samples, the proposed test is more powerful than the classical Pettitt test in detecting the change point. The proposed test can be an important tool for detecting abrupt changes in water availability, in support of hydroclimatological resources decision making.     

Estimation of shear wave velocity of earth dam materials using artificial blasting test

The objective of this study is to estimate the shear wave velocity of earth dam materials using the vibration generated from artificial blasting events, and to verify its applicability. In this study, near-field artificial blast testing and monitoring were carried out at the Seongdeok dam, Korea, as the first blasting tests to be carried out on an existing dam in Korea. Vibrations were induced by four different types of blasting, using various explosive charge weights and depths of blasting bore-holes. During the tests, acceleration time histories were measured at the rock outcrop adjacent to the point of the explosion, and at the crest of the dam. The fundamental frequency of the target dam was computed from the frequency analysis of measured acceleration histories. Numerical analyses were carried out, varying the shear modulus of the earth fill zone and using the acceleration histories measured at the rock outcrop as input ground motions. From a comparison between the fundamental frequencies calculated by numerical analyses and those of measured records, the shear wave velocities with depth, which are closely related to shear moduli, could be estimated. It is found that the effect of different blasting types on shear wave velocity estimation for the target dam materials is negligible, and that shear wave velocity can be consistently evaluated. Furthermore, by comparing the evaluated shear wave velocity with empirical formulae from previous research, the applicability of the method was verified. Therefore, in cases of mid-to-small earth dams, where the earthquake record is not available, the shear wave velocity of earth fill materials can be reasonably evaluated using blasting vibration records obtained at the site adjacent to the dam.     

16种地震科学期刊载文被引统计分析

依据《中国学术期刊文献评价统计分析系统》（V 1.0）,统计分析了2003~2007年16种地震科学期刊的总被引频次、影响因子、被引半衰期、即年指标、Web即年下载率等被引指标和较高频次被引论文。同时对期刊的现状进行了初步讨论,并提出了一些建议,以期为办刊提供一定的参考。     

2011年“7·3”特大暴雨天气过程诊断分析

为了更好的了解暴雨发生的机制且为未来预报奠定基础,需要对暴雨天气过程进行诊断分析.通过利用自动站降水观测资料、台站探空资料和NCEP逐6小时再分析资料,总结分析了成都地区2011年7月03至04日特大暴雨天气过程的环流背景和主要影响系统,并对相关物理量进行了诊断分析,结果表明:(1)这次降雨主要是在高空副高的突然加强西伸、低空西南急流的水汽输送和本地积聚的不稳定能量与弱冷空气侵入共同作用下产生的.(2)暴雨开始前,成都地区位于高空水汽通量散度梯度大值区北侧的辐散区.随着暴雨发展,水汽通量散度梯度区向北移动.(3)水汽通量散度正负临界值区和湿位涡对于本次降水落区的预报有较好的指示意义.在强降水区域,低层湿位涡的垂直正压项为明显的正值中心,斜压项为梯度大值区,斜压性很强.(4)风场在850hPa等压面和低层θe=325K(大约750hPa)等熵面上均表现为气旋式弯曲,有利于强降水的发生.     

风廓线雷达对折射率结构常数的实测分析

大气折射率结构常数（Cn2）是大气中折射率大小的体现,为了改善风廓线雷达（WPR）数据质量,提高WPR数据业务应用的可靠性,对边界层风廓线雷达近1年的实测数据采用归纳对比的方法,分析得到Cn2与温度湿度变化的关系,并总结出成都地区晴朗天气下,四季Cn2量级的变化范围,与理论推导一致.夏天10-12到10-20,春秋10-13到10-20,冬天10-14到10-21,此外,根据降水量大小不同,Cn2提升3到6个量级,获得这些定量的范围,为相关风廓线雷达产品识别提供了方法和依据.     

南黄海西部陆架区表层沉积物稀土元素及其物源分析

对南黄海西部陆架区486个表层沉积物样品的稀土元素进行了测试分析。结果表明:稀土元素总量分布特征受粒度影响,其含量总体上随平均粒径的减小而升高,但在局部站位其含量还可能受矿物控制。稀土元素相关参数,如轻重稀土元素分异度、铈异常以及铕异常基本不受粒度影响,而主要受源岩组分控制,可以进行有效的物源判别。研究区不同站位沉积物中稀土元素配分曲线均为右倾的负斜率模式,相对富集轻稀土元素,显示中等程度的铕负异常,无明显铈异常。稀土元素相关参数物源判别表明研究区物质主要来源于黄河。     

Modeling the Effects of Meteorological Factors on SO2 and PM10 Concentrations with Statistical Approaches

Air quality has been deteriorated seriously in urban areas as a result of increasing anthropogenic activities. Meteorological conditions affect air pollution levels in the urban atmosphere significantly due to their important role in transport and dilution of the pollutants. This paper aims to investigate usability of some promising statistical methods for examining the impacts of metrological factors on SO₂ and PM10 levels. Data were collected from city centre of Kocaeli in winter periods from 2007 to 2010 as pollutant concentrations increase in winters due to expanding combustion facilities. Results of bivariate correlation analysis showed that humidity and rainfall have remarkable negative correlations with the pollutants. Multiple linear regression models and artificial neural network (ANN) models were used to predict next day's PM10 and SO₂ levels. In regression models calculated R² values were 0.89 and 0.75 for PM10 and SO₂, respectively. Among the various architectures, single layer networks provided better performance in ANN applications. Highest R² values were obtained as 0.89 and 0.69 for PM10 and SO₂, respectively, by using appropriate networks.