Nonlinear Analysis of the Frequency-magnitude Relationship in the Western Circum-Pacific Region

— It has long been realized that the linear Gutenberg-Richter model arduously describes the frequency-magnitude relationship for the magnitude span ranging from small to large earthquakes because of the breakdown of the self-similarity rule due to the changing scaling of the magnitude. Three different segments should be observed from small (usually M < 3.0), through moderate (M < M_c, where M_c is the frequency-magnitude turning point caused by the seismogenic thickness), to large earthquakes (M M_c). We will only concentrate on the moderate and large earthquakes due to their importance. The breakdown of the self-similarity rule from moderate to large earthquakes occurs where the earthquake is big enough to cut through the entire seismogenic layer. A nonlinear hyperbolic model, which fits two linear relations smoothly, is studied in the present paper, where N is the cumulative number of earthquakes with magnitudes larger than or equal to M; a₁ to a₅ are constants to be calculated. The G-R linear relation is actually a special case of the present nonlinear model, i.e., a₃ or a₅ equal to zero. The nonlinear form, with the support of a reasonable physical mechanism, can generally give a better fitting with comparatively minor errors for complete data sets, especially for the areas where large earthquakes are numerous. In order to demonstrate its superiority to the linear G-R relation, thirteen seismogenic zones are examined around the western part of the Circum-Pacific region and western part of China and it is found that the fitting errors from this nonlinear model are, as expected, generally much smaller than those for G-R. Furthermore, the parameter a₄ is believed to relate with the saturated magnitude M_c,which to some extent reflects the mean thickness of the seismogenic layer.Acknowledgement. The author thanks Dr Paul W. Burton for his useful discussions. He appreciates two anonymous reviewers comments and suggestions which enhanced the quality of the paper. This research was partially supported by the project EPAN-M.4.3/2013555 of bilateral cooperation between Greece and China funded by the General Secretariat of Research & Technology of Greece and by the project of UK-China Science and Technology Fund funded by the British Council. Some figures were made with GMT software (WESSEL and SMITH, 1995).     

The regional development in a multi-cultural background

China is a country with many nationalities. Each of them has formed its own special culture, which is different from the mainstream of majority Han nationality, by adapting to geo-environment during history. Due to different backgrounds, the regional developmental model of minorities in the western China is different from the Han nationality and western countries. Combining a knowledge-based civilization and sustainable development, the minority areas can seek the systematic integration of culture-economy-ecology. Based on this, the paper suggests that the minority areas in western China should take the way of emphasizing developmental quality rather than developmental quantity for a harmonious system of culture-economy-ecology. Some approaches for developing minority areas in western China have been put foreword. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49261001). Biography: LU La-chang (1963 —), male, a native of Shaanxi Province, Ph. D., professor. His research interests include urban and regional studies. E-mail: lachanglu@163.net     

兰坪—思茅盆地砂页岩中脉状铜矿床的特征及成因

兰坪－思茅中新生代盆地中的铜矿床,主要产于由砂岩、粉砂岩和页岩组成的含盐结色碎屑岩建造中,故一些研究者将其与典型的陆相砂页型铜矿床相类比。但就铜矿化的产出形式、元素的矿物组合、矿石稀土配分特征以及同位素组成特点等而言,均与典型砂页岩型铜矿床存在显著差异,而与一些地热区的矿化作用相似。说明研究区砂矾岩中的铜矿床具有特殊的成矿机理。     

川西义敦岛弧带晚三叠世植物化石

通过 1∶2 5万区域地质调查和三叠系专项研究 ,在义敦岛弧带的四川省新龙县雄龙西、白玉县热加获得一批植物化石 ,计 15属 2 0种 ,其中包括两个新种 ,一个属种为国内首次发现。这些化石不仅丰富了本区植物化石组合内容 ,而且对地层时代的确定及与邻区的对比和沉积环境的恢复提供了重要的古生物依据。     

西部开发的资源战略问题

西部的资源赋存并不丰富。对全国经济发展有巨大意义的关键性资源并不多 ,由资源特性和经济发展的趋势决定了东部地区对西部地区资源的依赖降低 ,对于西部长期以资源开发为重点的发展模式所造成的多种疾患 ,以及目前国内外资源环境形势 ,提出西部注重开发技术、知识资源 ,培育特色产业 ,大力发展旅游业和建立国家资源安全战略的西部开发资源战略     

新疆西天山那拉提构造带变质核部杂岩地质构造特征

新疆西天山那拉提构造带变质核部杂岩分布于新疆巩留县那拉提山山脊北侧，整体沿那位提南缘构造带北侧呈近东西向展布，为一套由高级变质表壳岩、灰色片麻岩组成的早前寒武系高级片麻岩系，历经多期不同构造体制变形变质改造与再造，形成多相片麻岩系，并呈长垣状变质核部杂岩隆升，构成那拉提造山带的核部构造物质组成。     

祁连山西段古元古代北大河岩群中斜长角闪岩的地球化学特征及构造背景

以大陆碎块形式残存于北祁连造山带内部的古元古代北大河岩群早期发育有大量的斜长角闪岩,其原岩为玄武岩,Alk-∑FeO-MgO图解、REE特征、里特曼组合指数等均显示斜长角闪岩属钙碱性系列范围,个别显示弱碱性,斜长角闪岩具有较高的Al2O3、∑FeO和低的Mg#,这些特点反映其成分演化程度较高,表明火山岩的形成与古老地壳的活化有关,有较强分异的稀土元素分配模式,在Ti-Zr-Y图、Ni-FeO/MgO图解和Ta/Yb-Th/Yb图解上斜长角闪岩均显示火山弧或活动大陆边缘的特点,在玄武岩的地球化学形式图、稀土元素整体特征与钙碱性岛弧玄武岩基本相同;87Sr/86Sr=0.71617～0.72033,143Nd/144Nd=0.512414～0.512495,εNd=-2.79～-4.37.显示出壳源性质或者是受到大陆下地壳的混染作用而形成.因此推测斜长角闪岩的原岩为不同程度部分熔融的岩浆弧作用的产物,说明在古元古代华北克拉通和柴达木克拉通之间存在古洋盆的俯冲消减.     

豫西铝土矿成矿地质条件及找矿前景

豫西铝土矿矿床产于寒武系-奥陶系的长期风化侵蚀面之上的石炭系本溪组中，其常分布在早古生代隆起区边缘，构造环境相对稳定，沉积间断时间长，沉积相为滨海-泻湖-沼泽相，下伏地层为纯灰岩，古岩溶凹斗对成矿有利，砂状结构的铝土矿矿石质量最好。经多年的探采，豫西已从找露头矿进入找隐伏矿时期。成矿条件表明，豫西仍有广阔的找矿前景。     

绿色发展理念与西部贫困地区发展

绿色发展理念的核心是以人为本的发展思想,是经济发展和环境保护相协调的发展。在西部大开发的背景下,西部贫困地区的发展主要面临着高强度的经济开发和环境保护之间的矛盾,从宏观的角度来分析西部贫困地区的地域特征和致贫原因,可以发现西部贫困地区的发展问题关键在于如何推动绿色发展,在于如何化解人与自然环境日益激化的冲突,只有采取了积极的绿色发展理念和策略,才能缩短西部贫困地区与发达地区的差距,才能走上可持续发展之路。     

西太平洋暖池次表层海温异常 与ENSO循环的相互作用

利用1964～1993年的太平洋次表层海温资料,进一步分析研究了西太平洋暖池次表层海温异常与ENSO循环的关系。合成及相关分析的结果进一步表明,西太平洋暖池次表层海温的暖（冷）异常及其东传对ENSO的发生起着十分重要、且更直接的作用。然而,赤道西太平洋异常纬向风是造成次表层海温异常东传的重要原因,而纬向风的异常又是由于东亚冬季风异常活动所引起的,这间接地说明了异常东亚冬季风对西太平洋暖池次表层海温距平东传的重要作用。通过研究还发现,ENSO发生后,北半球副热带地区将有次表层暖（冷）海温距平沿着10～20oN纬带西传,这是导致西太平洋暖池次表层海温发生异常的重要原因之一。也就是说,西太平洋暖池次表层海温异常与ENSO循环之间是相互影响、相互作用的。