Effect of Aftershocks on Assessment of Seismic Hazard for Hebei Seismic Zone,China

In this paper,the earthquake hazard parameters(λm,b and Mmax) from the maximum likelihood method for the raw catalogue and declustered catalogues have been used to discuss the effect of the aftershocks on the earthquake hazard estimation.The declusterd catalogues have been compoiled from the raw catalogues by deleting the aftershocks in different time interval after main shock according to the criteria for the aftershock activity period.As an example,Hebei seismic zone is taken to show the effect of the aftershock on the earthquake hazard assessment because three strong earthquakes with the aftershocks occurred from 1966,to 1976,The results have been shown that the effect of the aftershocks on the parameters λm,b is significant.The difference between the clustered and declustered catalogues has reached in seismic activity rate and recurrence period,at most,45% and 90%,respectively,But the diffeence in Mmax is smaller,Based on this,the suggestion that the aftershocks should be omitted in the estimation of the earthquake hazard could be made,but how long the aftershocks activity duration is still left to the future research.     

Estimation of tree transpiration and response of tree conductance to meteorological variables in desert-oasis system of Northwest China

Transpirations of three dominated tree species, namely Mongol Scotch Pine (Pinus sylvestris var. mongolica Litvin), White elm (Ulmus pumila) and Gansu Poplar (Populus gansuensis Wang et Yang) in oasis shelter forest (Linze site) and of two dominated tree species,namely Euphrates Poplar (Populus euphratica Oliv.) and Russia olive (Elaeagnus angustifolia Linn.) in lowland desert (Erjinaqi site) have been estimated using measured sapflow in summer,autumn and winter, 2002 and in spring, 2003. An ENVIS System was used for each site to measure microclimate variables, soil moisture and sapflow every half an hour, and the study time scale is one day. In the 104 days of observation during the growing season at the Linze site, the average daily sapflow of Gansu Poplar is 9.93L·d-1,and the average transpiration per unit leaf area is 1.99mm·d-1.For White elm tree,the daily average sapflow is 4.08L·d-1,while the daily average transpiration per unit leaf area is 0.49mm·d-1.The values for Mongol Scotch Pine are 3.91L·d-1 and 0.25mm·d-1,respectively.In the total 73 days of observation during the growing season at the Erjinaqi site, the daily average sapflows of Russia olive and Euphrates Poplar are 12.1 and 20.97L·d-1,respectively,and the average transpirations per unit leaf area are 0.22 amd 0.31mm·d-1,respectively.In the observation period of the growing season,tree conductances of Mongol Scotch Pine, White elm, Gansu Poplar or Russia olive show an exponential relationship with the daily average air temperature or vapour pressure deficit, but the relationship is not so obvious between tree conductance and global radiation. The transpiration process of each tree species is affected by all the observed four environmental variables. The response of tree conductance to different climatic factors changes with tree species. The effect of the same factor to the same tree species is also variable in different growing stages. The sapflow of every tree species is relatively large in later spring to early summer, and low in summer, and then reaches its largest value in later September. In the mid-November, the sapflow is relatively large, especially the deciduous tree species. This may be characteristic of the tree species in Arid Regions of Northwest China.     

由跨断层形变测量反映的华北地块近期断裂活动特征

通过对华北地块不同构造部位、不同地震活动时段的跨断层测量资料研究表明，华北地块对于NE走向断裂作用为主的构造单元(包括地块和边界带)的强震活跃时段的断层运动速率明显小于强震不活跃时段；对于NW走向断裂作用为主的构造单元，其强震活跃时段的断层运动速率明显大于强震不活跃时段；对于NE、NW走向断裂共同作用的构造单元，断层运动速率变化特征类似于NW走向断裂作用为主的构造单元。结果还表明，华北地块现今强震活动主要受NW走向断裂的控制。     

丽江7.0级大震前地震活动分形异常

该文提供１９９６年２月丽江７．０级大震前滇西北地震活动空间容量维、关联维、信息熵十分显著的异常图像；这些异常是在大震孕震区形成，应变释放加速阶段之后出现的，恰好揭示了源区、近源区大释放前的非线性变化过程。这与１９６５年以来云南及邻区８组大震前地震分形研究的结论完全一致；进一步说明地震活动分形异常对地震孕育阶段具有重要的指示意义。     

厦门岛地壳稳定性基本特征

根据地质结构、遥感解译、物探、微震观测、地震硅热流值等资料分析，确定厦门岛属于较稳定地块－安全岛；由于断裂活动性，新构造运动、工程地质、水文地质和地貌单元等特征的差异，可进一步划分为４个稳定性亚区。     

动力变质与金的成矿作用

动力变质作用对金矿有直接的成矿意义。动力变质过程就是成岩成矿过程,不同程度的动力变质相带金的迁移、富集规律不同,形成的矿石建造也有差异。动力变质作用中岩石力学变形梯度不一定都与深度有关,常因岩性和应力集中面分布不均一,水平方向脆性—韧性应变带相间出现。     

三维非稳定流含水层储能的数值模拟研究

本文建立了一个三维含水层储能模型。它是由一个描述地下水运动的水流模型与一个描述含水层中热量运移的热量输运模型耦合而成。为了考察地下水的运动状态对含水层中热量输运的影响，地下水流被处理成三维非稳定流。该模型被应用于上海群井储能试验，储能模型用特征线Ｄｏｕｇｌａｓ－Ｂｒｉａｎ ＡＤＩ法求解。通过本模型与稳定流储能模型的结果相比较，发现本模型的结果较好，诸观测孔各时段的绝对误差均值为０．６５℃，平均相对     

试论厦门筼筜港区的地质构造演化

通过港区基底岩石地质构造、第四纪沉积、地壳升降活动和断裂活动性等特征的分析，论述港断陷海湾形成发展的过程，总结了港区由上新世、更新世断裂复活港湾雏形阶段→全新世断陷发展阶段→近代成型稳定阶段的基本演化过程。     

我国太阳能分布的非线性回归模式

本文通过非线性拟合,给出我国太阳总辐射Q和直接辐射S＇的年值和月值分布的计算公式,年值公式适用于任一地点,月值公式适用于任一月分和任一地点,简化了计算程序。验证结果表明,用这些公式拟合实测Q的累年平均年值和月值的相对误差66站平均分别为4%和5%,拟合实测S＇的累年平均年值和月值的相对误差55站平均分别为6%和10%。因此可用这些公式估算无实测辐射资料地点的上述辐射量。