Magma ascent beneath Unzen Volcano, SW Japan, deduced from the electrical resistivity structure

The resistivity structure of Unzen Volcano has been revealed by extensive magnetotelluric surveys since the first eruption on November 17, 1990. This structure comprises a highly resistive surface layer, a low-resistive second layer at several hundred meters depth, interpreted as a water-saturated layer, a resistive third layer, and a low-resistive fourth layer at 10 km depth, possibly related to the deep magmatic activity. The structure has influenced the volcanic activity of Unzen. This activity was characterized by a series of dramatic changes in eruption type: a minor phreatic eruption on November 17, 1990; phreatic eruptions after February 12, 1991, preceded by several weeks of volcanic tremor; phreatomagmatic eruptions after April 9, and dome effusion beginning May 19, 1991. This paper presents a hypothesis in which the top of the magma column rose about 20 m/day, reached the base of the water-saturated layer at the end of January, 1991, and approached the upper boundary of this layer on April 9. Thus, the temporal change of eruption type and associated phenomena are systematically explained by an interaction between magma and groundwater contained in the saturated layer.     

城市森林生态服务功能在城市景观规划中应用的思考

回顾了景观规划的发展历程,并依据城市森林生态服务功能的内涵,指出当前国内外景观规划中存在的缺陷与不足.旨在通过对二者关系的分析,解读景观生态学理论引入规划中的功能缺失,以期重新唤起人们对于城市森林生态服务功能重要性的关注,并尝试将城市森林生态服务功能的研究成果应用于景观规划领域,为景观规划的定量化提供数据基础和科学依据.     

金堆城钼矿石的物质组成及钼、铜、铅的赋存状态研究

金堆城钼业公司是我国重要的钼业基地,选矿产品质量与国外同类产品相比还有差距,存在质量不稳定的因素,如１９９７～１９９８年间,钼精矿中铜、铅杂质含量超标,影响了产品的销售;钼回收率较低,造成矿产资源的浪费。因此,开展钼矿石工艺矿物学研究,查明现采矿石的物质组成,钼、铜、铅的赋存状态、主要矿物的嵌布特征等工艺矿物学特征,对于进一步优化选矿流程和工艺条件,提高产品质量是十分必要的。１　样品的采集与制备取样点按１００×１００ｍ的网度在采场各平盘掌子面的交叉点上布置,沿掌子面的坡底线取样,每个样点采集化学…     

构造-沉积分异原理及其地质意义*

构造-沉积分异是地球表层的常见地质现象,发生于沉积盆地、造山带与克拉通等岩石圈构造单元,表现为岩石圈的深、中、浅层始终发生着沉积物、流体、能量与力的交换与分异过程。文中从物质组成、时空分布与力学机制等方面阐述构造-沉积分异的基本特征,并以中国沉积盆地为例进行分析。作者首先将构造-沉积分异定义为“由构造应力、热力、重力、地幔动力等因素引起地表地形差异,从而导致沉积物源、搬运体系与沉积作用变化的过程”;认为构造-沉积分异发生在不同尺度的洋-陆系统、盆-山系统、隆-坳系统、凸-凹系统与高-低地貌系统,受基底结构、强度与活动性的明显控制,构造应力、重力、热力、地幔动力等控制了该分异机制; 强调随时间演变出现构造-沉积分异演化旋回,表现为伸展期裂陷向聚敛期隆坳转变,碳酸盐岩分异台地向统一台地转变。上述控制因素与机制在时空上可以发生复合,导致多类构造-沉积分异作用出现。研究构造-沉积分异作用,可以为重建地球历史、加快矿产资源勘查和改善人类宜居环境做出贡献。     

水性多彩涂料的制备工艺研究

阐述了改性聚乙烯醇胶水的制备工艺,并以此作彩粒成型剂,应用羟乙基纤维素———膨润土复合增稠剂作抗沉剂和稳定剂,与苯丙乳液等成膜剂、无机颜料等制成无毒、阻燃的水性多彩涂料。     

溃屈型滑坡稳定性分析中三个问题的探讨

针对溃屈型滑坡稳定性分析中的三个问题,即滑带土强度参数的分段取值,顺层段与切层段分界点和水的作用,逐一进行初步探讨。     

北部湾6.1,6.2级地震序列的环境应力场

应用Ｐ波初动半周期直接测定环境剪应力值的方法,测定了北部湾６．１,６．２级地震前后中小地震的环境剪应力值τ０,由此分析了北部湾地震过程的环境应力场特征。结果表明,北部湾６．１级地震后平均剪应力值较高,达１８ＭＰａ左右;６．２级地震及两次５级余震后剪应力值下降很快,降至目前的６ＭＰａ左右。在此基础上对北部湾地震活动趋势作了初步分析。     

PHENOMENA AND CONTROLLING FACTORS IN DRAWDOWN FLUSHING PROCESSES

IINTRODUCTIONByutilizingthenatUralpowerofflow,hydraulicflushingisaneconomicaltechniquetoremovethedepositedsedimentineitherasettlingbasinorareservoir.Inmanyreservoirsaroundtheworld,hydraulicflushinghasbeenprovenasaneffectivemethodtosustainthereservoirstoragecapacity.Hydraulicflushingprocessesmayinvolveboththeprocessesofscouringpreviousdepositsandpassingincomingsediment-ladenflow,suchasgravitycurrent,throughareservoirtobereleased.Inthisarticle,onlytheformercaseisdiscussed.Thekeythinginthef…     

Theoretical discussion and Monte-Carlo simulations for a Negative Binomial process paradox

The idea of an over-threshold sampling is to retain all the events of a time-series exceeding a given threshold. The probabilistic analysis implies estimating two statistical models, one describing the occurrence of the events (date of the events), the other describing their magnitude (value of the local maximum). These two models are then combined to obtain the distribution of the annual maxima. A well-known result of a Poisson process is that waiting time, defined as the duration between two successive events exceeding the threshold, is exponentially distributed. The assertion that the waiting time of a Negative Binomial process is also exponentially distributed seems to be in obvious contradiction with the Poisson process properties. A theoretical discussion and Monte-Carlo simulations are presented to solve this apparent paradox.     

A simulation system of seismogeny, occurrence and development of earthquakes

A personal computer processing system for simulation of earthquake seismogeny, occurrence and development is given in this paper. It can automatically process the discontinuous events such as earthquake occurrence during computation. The program can be paused when you want to display the computation results. After you analyze these graphical results the simulation process can be continued.