利用怀来地震台水管仪观测资料检测地球自由振荡

利用怀来地震台水管仪的数字化观测资料,采用功率谱密度估计方法,在没有对资料去固体潮处理的情况下,准确获得2004年12月26日苏门答腊9.0级地震激发的_0S_2—_0S_(38)基频球型自由振荡,并与PREM模型的理论自由振荡周期进行对比,发现实测振荡周期与PREM预测的振荡周期吻合,除_0S_2、_0S_4、_0S_7振型的观测周期和PREM模型理论周期的相对误差大于0.3%外,其他振型的观测周期和PREM模型理论周期的相对误差大都集中在0.1%左右,同时检测到7个谐频球型振荡和10个环型振荡。可以从水管倾斜仪的观测资料中提取地球球型振荡信息,为地球自由振荡的研究提供一种新的仪器观测方法。     

印度洋8.7级地震及对未来地震趋势的讨论

本文通过对2004年12月26日印度洋8．7级大震前7级地震的分析,指出8．7级大地震前存在两支7级地震条带。文中对两支7级地震条带进行时空分析,得出汤加群岛-印度尼西亚7级地震带由东向西逐渐迁移的特点。在本文的讨论中,针对中蒙交界-苏门答腊M≥7．7级地震南北对迁的特点,对未来地震趋势进行了分析。     

Properties of thermally metamorphosed coal from Tanjung Enim Area, South Sumatra Basin, Indonesia with special reference to the coalification path of macerals

Thermally metamorphosed Tertiary age coals from Tanjung Enim in South Sumatra Basin have been investigated by means of petrographic, mineralogical and chemical analyses. These coals were influenced by heat from an andesitic igneous intrusion. The original coal outside the metamorphosed zone is characterized by high moisture content (4.13–11.25 wt.%) and volatile matter content (> 40 wt.%, daf), as well as less than 80 wt.% (daf) carbon and low vitrinite reflectance (VR_max = 0.52–0.76%). Those coals are of subbituminous and high volatile bituminous rank. In contrast the thermally metamorphosed coals are of medium-volatile bituminous to meta-anthracite rank and characterized by low moisture content (only < 3 wt.%) and volatile matter content (< 24 wt.%, daf), as well as high carbon content (> 80 wt.%, daf) and vitrinite reflectance (VR_max = 1.87–6.20%). All the studied coals have a low mineral matter content, except for those which are highly metamorphosed, due to the formation of new minerals.The coalification path of each maceral shows that vitrinite, liptinite and inertinite reflectance converge in a transition zone at VR_max of around 1.5%. Significant decrease of volatile matter occurs in the zone between 0.5% and 2.0% VR_max. A sharp bend occurs at VR_max between 2.0% and 2.5%. Above 2.5%, the volatile matter decreases only very slightly. Between VR_r = 0.5% and 2.0%, the carbon content of the coals is ascending drastically. Above 2.5% VR_r, the carbon content becomes relatively stable (around 95 wt.%, daf).Vitrinite is the most abundant maceral in low rank coal (69.6–86.2 vol.%). Liptinite and inertinite are minor constituents. In the high rank coal, the thermally altered vitrinite composes 82.4–93.8 vol.%. Mosaic structures can be recognized as groundmasss and crack fillings. The most common minerals found are carbonates, pyrite or marcasite and clay minerals. The latter consist of kaolinite in low rank coal and illite and rectorite in high rank coal. Change of functional groups with rank increase is reflected most of all by the increase of the ratio of aromatic C–H to aliphatic C–H absorbances based on FTIR analysis. The Oxygen Index values of all studied coals are low (OI < 5 mg CO₂/g TOC) and the high rank coals have a lower Hydrogen Index (< 130 mg HC/g TOC) than the low rank coals (about 300 mg HC/g TOC). T_max increases with maturity (420–440 °C for low rank coals and 475–551 °C for high rank coals).Based on the above data, it was calculated that the temperature of contact metamorphism reached 700–750 °C in the most metamorphosed coal.     

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印度尼西亚苏门答腊岛唐塞斑岩铜钼矿床成矿流体及成矿物质来源—来自氢、氧、硫和铅同位素证据

唐塞斑岩铜钼矿床位于苏门答腊岛北部,是岛上规模最大的矿床。本文在系统的野外观察及室内岩相学观察的基础上,通过开展系统的流体包裹体的岩相学、显微测温及H、O、S、Pb同位素测试分析,查明该矿床的成矿流体特征,分析探讨其成矿物质来源。研究表明,含矿石英脉中主要发育气液两相包裹体,主成矿阶段流体为中高温（280~386℃）、中等盐度（11.46~15.27）wt%NaCleqv、中等密度（0.73~1.11g/cm3）的流体,成矿深度为7.17~9.59km,矿床形成于中等深度环境;矿石石英脉中石英的δ18OH2O值范围为4.6‰~6.3‰,含矿石英脉中石英的δ18DV-SMOW值范围为-64.9‰~-73.5‰,成矿流体主要为岩浆水,有一定量的大气降水混入。矿石中硫化物组成变化范围窄,为1.32‰~2.23‰,多数集中在1‰左右,且具有呈塔式分布特点,表明主要为岩浆硫源;矿石硫化物的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb比值分别为18.767~19.032、15.689~15.899和38.683~39.159,具有显著的上地壳和地幔混合性质,表明成矿物质可能与大洋沉积物和洋壳的部分熔融有关。以上研究证明,唐塞矿床属于中-高温中等深度斑岩型铜钼矿床。     

2012年4月11日苏门答腊8.6级地震前后川滇地区波速变化研究

利用2012年1~6月川滇地区(21°～34°N, 97°～108°E)99个测震数字地震台的连续波形资料, 采用背景噪声层析成像方法反演了2012年4月11日苏门答腊8.6级地震前后川滇地区的波速变化, 同时研究了该地震前后川滇地区地震活动的变化特征。 结果表明, 川滇地区波速结构呈现龙门山断裂带南段至元谋—绿汁江断裂带和安宁河断裂带波速降低而两侧波速升高的特点。 同时, 波速变化与地震活动性变化具有明显的相关性: 在宁蒗—木里和乐山—雅安一带波速增高显著, 地震活动速率也增加; 在龙门山断裂带南段至安宁河断裂带上则表现为明显的波速降低, 而安宁河断裂带也是地震活动速率降低区域。 这表明本研究得到的波速变化的结果有一定的可信度, 也为背景噪声方法应用到地震预测提供了一种可能的途径。     

Remote Sensing of Chlorophyll and Sea Surface Temperature in Indian Water with Impact of 2004 Sumatra Tsunami

The daily and weekly averaged Indian Remote Sensing satellite IRS-P4 Ocean Color Monitor (OCM) derived chlorophyll images were generated and interpreted in terms of pretsunami, tsunami, and posttsunami periods in the Bay of Bengal and Andaman Sea. There has been observation of increase in chlorophyll concentration up to 5.0 mg/m3 in the tsunami-affected coastal waters. The high chlorophyll concentration lasted for about one week after the tsunami catastrophe. The standard deviation for different transects in the tsunami-affected water were plotted. The high chlorophyll has been observed for selected transects in the aftermath of the tsunami event in coastal regions, and offshore water has also shown increase in chlorophyll concentration (～1.0 mg/m3) in the Bay of Bengal. The analysis indicated that the tsunami waves might have displaced and spread the high chlorophyll coastal water towards offshore. NASA Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua daytime sea surface temperature (SST) daily images were retrieved and displayed during December 21, 2004, to January 6, 2005, and indicated the cooling (0.5–1°C) in the Bay of Bengal around Tamil Nadu and Andhra coast. The National Oceanographic and Atmospheric Prediction-National Center for Environment Prediction (NOAA-NCEP) data for five weeks (December 9, 2004–January 12, 2005) were retrieved to study the SST variability trend in prior to MODIS data and indicated 0.5–1°C cooling of the Bay of Bengal water off Kakinada, Chennai, Cuddalore, and Nagapattinam region on December 26 and 28, 2004.     

Can electromagnetic disturbances related to the recent great earthquakes be detected by satellite magnetometers?

On December 26, 2004 the world's fourth largest earthquake since 1900 and the largest since the 1964 Prince William Sound, Alaska earthquake, occurred off the west coast of northern Sumatra with a magnitude of 9.3. On March 28, 2005 another event of magnitude 8.7 took place in the same region. The December 26, 2004 earthquake has prompted scientists to investigate possible electromagnetic signatures of this event, using ground magnetic observations. Iyemori et al. [Iyemori, T. et al., 2005. Geomagnetic pulsations caused by the Sumatra earthquake on December 26, 2004. Geophys. Res. Lett., 32, L20807, doi:10.1029/2005GL024083.] have suggested that a 3.6 min long geomagnetic pulsation, observed shortly after this event, was generated by the earthquake. They have speculated that a 30 s magnetic pulsation was also caused by the earthquake. Here for the first time, CHAMP satellite magnetic and electron density data are examined to find out if electromagnetic signatures which are possibly related to these recent megathrust earthquakes are observed in satellite magnetic data. We have shown that some specific features are observed after the two earthquakes, with periods of about 16 and 30 s. Our results favor an external source origin for the 30 s pulsation. Moreover, after more than 1 h, CHAMP magnetic data indicate the existence of a feature characterized by the same parameters (duration, amplitude, and frequency content), which could be associated with each earthquake, respectively. Further investigations are required in order to answer the question of whether these signals can be associated with earthquakes and to assign their possible usefulness with respect to earthquake development.     

印尼苏门答腊9.0级地震前地震活动图像异常特征研究

通过对2004年12月26日印尼苏门答腊9．0级大震前不同时空尺度地震活动性异常特征分析发现：①大震前10年，澳大利亚板块北部边界带深源地震活动显著增强，表现为频度增多、强度增大、震源深度增加等，特别是震源深度分布的非均匀性增大（即地震集中分布在500～689km深度间）；同期，苏门答腊岛及其附近肘≥7．0浅震活动也异常显著，形成长约1000km、宽300km的集中区。②震前1年全球肘≥7．0地震活动出现明显的平静一密集现象，且在密集阶段强震沿澳大利亚板块北部边界带呈带状展布；这时主震震源区附近出现5级地震空区。③震前半年澳大利亚板块北部边界带的东、西两端先后发生2次7级以上深震，其中1次发生在罕有深震活动的苏门答腊岛。④震前3天，澳大利亚板块北部边界带上4级以上地震呈带状展布。⑤震前4年澳大利亚板块北部边界带火山活动增强，特别是震前1年火山活动异常显著。     

The Indian Ocean tsunami of December 26, 2004: observations in Sri Lanka and Thailand

On December 26, 2004 a great earthquake (M _W 9.3) occurred off the western coast of Sumatra triggering a series of tsunami waves that propagated across the Indian Ocean causing damage and life loss in 12 countries. This paper summarizes the observations of lifeline performance, building damage and its distribution, and the social and economic impact of the tsunami made by the Earthquake Engineering Field Investigation Team (EEFIT) in Thailand and Sri Lanka. EEFIT operates under the umbrella of the UK’s Institution of Structural Engineers. It is observed that good engineering practice can reduce economic losses, but additional measures are required to reduce risk to life.