滇西北丽江,宁蒗两次强震前地震学异常的重复性

１９９６年２月３日云南省滇西北丽江,中甸交界地区发生７．０级地震,距１９７６年１１月７日,１２月１３日宁蒗６．７,６．４级地震仅９０千米,滇西北重复发生的这两次强震在地震学异常方面具有良好的重复性,强震前均在缅甸密支那地区发生３次６级地震,密支那强震的最大震级比滇西北强震震级小０．３～０．５级,强震前１～３年均出现中强震和调制中强震的频繁活动,中强震包括调制中强震的活动除在形成的时间,范围大小有所     

永登5.8级地震前几项测震学指标的异常分析

对１９９５年７月２２日永登ＭＳ５．８地震前几项测震学指标的变化进行了分析，发现该次地震前有４项测震学指标有明显异常，它们是小震活动增强、背景性空区、小震活动条带及前兆震群     

山东地区及其海域近期地震活动特点

本通过对山东地区及其海域的历史地震和近代小震活动的分析，认为该区的历史地震活动，自１６８８年以来存在三个Ｍ≥５级地震活动空段；而１９６０年以来，该区ＭＬ≥４．５级地震具有８年的活跃时间段的特点。     

Seismicity trends and potential for large earthquakes in the Alaska-Aleutian region

The high likelihood of a gap-filling thrust earthquake in the Alaska subduction zone within this decade is indicated by two independent methods: analysis of historic earthquake recurrence data and time-to-failure analysis applied to recent decades of instrumental data. Recent (May 1993) earthquake activity in the Shumagin Islands gap is consistent with previous projections of increases in seismic release, indicating that this segment, along with the Alaska Peninsula segment, is approaching failure. Based on this pattern of accelerating seismic release, we project the occurrence of one or moreM7.3 earthquakes in the Shumagin-Alaska Peninsula region during 1994–1996. Different segments of the Alaska-Aleutian seismic zone behave differently in the decade or two preceding great earthquakes, some showing acceleration of seismic release (type A zones), while others show deceleration (type D zones). The largest Alaska-Aleutian earthquakes—in 1957, 1964, and 1965—originated in zones that exhibit type D behavior. Type A zones currently showing accelerating release are the Shumagin, Alaska Peninsula, Delarof, and Kommandorski segments. Time-to-failure analysis suggests that the large earthquakes could occur in these latter zones within the next few years.     

鲁苏皖交界地区地震活动特点浅析

从历史及现代两个时期对三省(鲁苏皖)交界区域地震活动特点、规律进行了讨论和分析。从历史活动周期及小震空区空间演化特征,以不同的角度讨论分析研究了所属区域的震情发展趋势。指出近期(1998年起)形成的空区为孕震空区,且空区周围应力场背景显示增强的态势,并依据历史地震南北迁移特点,认为34°N以南区域为未来发生5级以上地震的地区,应注意加强监视。     

孕震空区和逼近地震在台湾地震中的应用

本文应用陆远忠等人提出的孕震空区和逼近地震方法 ,分析了台湾及其东部海域所有资料较完整的 6 0级以上的地震。结果表明该区普遍存在孕震空区和逼近地震。在判定是否为孕震空区时 ,采用同样的三个标志。用所得到的数据计算经验公式。最后得出 5点初步结论     

人的地域属性对区域政策的解释及影响

从地区发展及区域政策，分析了目前中国区域政策中政策绩效差和市场失灵两难境地的主导因素，通过对人及其背后地域属性的二元相互关系分析，认为人作为活跃的经济要素，与地域的对应性应该弱化，提出今后区域政策的政策目标应该是引导人群间分配的相对公平，使各地区在生态、景观、文化上保持丰富性和多样性，而不是徒劳地将地区作为政策对象或片面强调缩小地区差距。     

New constraints on the seismic history of the Castrovillari fault in the Pollino gap (Calabria, southern Italy)

The Pollino Range area represents the mostprominent gap in seismicity within thesouthern Apennines. Geomorphic andtrenching investigations along theCastrovillari fault indicate that thisnormal fault is a major seismogenic faultwithin the southern part of this gap. Atleast four surface-faulting earthquakeshave occurred on this fault since latePleistocene age. Radiocarbon dating coupledwith historical consideration set thetime of the most recent earthquake as mostlikely to be between 530 A.D. and 900 A.D.,with the possible widest interval of530–1100 A.D. No evidence for this eventhas been found in the historical records,although its age interval falls within thetime spanned by the seismic catalogues.Slip per event ranges between 0.5 and1.6 m, with a minimum rupture length of13 km. These values suggest a M 6.5–7.0 forthe paleoearthquakes. The minimum long-termvertical slip rate obtained from displacedgeomorphic features is of 0.2–0.5 mm/yr. Avertical slip-rate of about 1 mm/yr is alsoinferred from trenching data. Theinter-event interval obtained from trenchdata ranges between 940 and 7760 years(with the young part of the intervalpossibly more representative; roughly940–3000 years). The time elapsed since themost recent earthquake ranges between aminimum of 900–1100 and a maximum of 1470years. The seismic behavior of this faultappears to be consistent with that of othermajor seismogenic faults of thecentral-southern Apennines. The Pollinocase highlights the fact thatgeological investigations represent apotentially useful technique tocharacterize the seismic hazard of `silent' areas for which adequate historical andseismological data record are notavailable.     

Low-temperature crystal structures of stibnite implying orbital overlap of Sb 5s2 inert pair electrons

The crystal structure of stibnite [Sb₂S₃, Pnma, a=11.314(2), b=3.837(2), c=11.234(3) Å, V= 487.7(3) ų at 293 K] was refined in situ at 230, 173, and 128 K. It is a major characteristic of the structure that the Sb–S secondary bonds enclosing Sb 5s² inert lone-pair electrons at 293 K are significantly shorter than the corresponding sum of the Sb and S van der Waals radii. Concerning the temperature dependence, although both the polyhedral volume and the cation eccentricity of the two SbS₇ polyhedra exhibit continuous contractions with decreasing temperature, the sphericity values remain constant, indicating isotropic shrinkage. Consequently, the geometries of Sb 5s² inert lone-pair electrons and ligand atoms remain unchanged at low temperatures. This is because the crystal structure of stibnite at low temperature induces contraction with attractive interactions, which is called the orbital overlap between Sb 5s² inert lone-pair electrons and ligand orbitals to maintain the coordination environment. In this case, Sb 5s² lone-pair electrons are not inert, but active. Such orbital overlaps of inert lone-electron pairs can provide a reasonable explanation for shorter secondary bonds and lower band gap energy of the binary compounds containing heavy elements such as Sb, Te, Pb, and Bi, which are key factors in tracing the origins of color, luster, and semiconductivity of their minerals or compounds.     

用LAI监测植被信息分析飞蝗生境

东亚飞蝗自20世纪80年代以来在我国再度猖獗危害。本文选择国家一类蝗区河北省黄骅市为实验区,用植被冠层孔隙度反演了该地区不同植被的LAI。从光学模型建立机理及数量分析的角度,分析和对比了四种由植被冠层孔隙度反演LAI的算法。结果表明,在四种估算方法中LAI-2000算法最适用于研究区植被LAI的估算。为了验证分析结果,用实测的植被盖度与四种算法反演的LAI进行了拟合。发现LAI与植被盖度之间呈明显的正相关关系,且LAI-2000算法最能反映研究区的植被特征。在此基础上,建立了LAI与飞蝗发生面积的关系模型,发现两者之间呈负线性相关,即随着LAI的减小,飞蝗的发生面积呈线性增大。研究结果为实时、快速、大面积监测蝗虫种群动态奠定了基础,并为合理、经济地防治蝗灾提供了科学依据。