腾冲地区构造地貌特征与火山活动的关系

通过对腾冲地区 (2 4°4 0′～ 2 5°30′N ,98°15′～ 98°4 5′E)构造地貌的分析 ,认为上新世以来本区存在的局部张应力环境是火山活动产生的重要因素。在对盆地发育过程和全新世火山活动分期对比研究基础上 ,探讨了该区新生代地壳活动的发展阶段 ,认为全新世以来 ,腾冲地区仍处于强烈活动阶段。     

华北第四纪火山作用研究

根据地层与同位素年代确定华北第四纪火山的时代为更新世 (Qp) ,距今 0 4Ma为火山活动高潮期。山西大同火山群东部火山为拉斑玄武岩 ,西部为碱性玄武岩 ;山东火山岩石碱性最强 ,为橄榄玄武岩 ,Sr同位素87Sr- 86Sr为 0 70 347～ 0 70 4 6 1,推测岩浆为地幔部分熔融的原始岩浆。对玄武岩中幔源包体的矿物进行了大量的电子探针分析 ,计算出其平衡温度为 880～ 110 0℃ ,平衡压力为 0 8～ 2 0GPa。由此推导的上地幔地温线低于由第三纪玄武岩中包体推导的地温线。上地幔的差异应力为 13～ 31MPa ,并随温度的升高而降低 ;应变速率为 7 78× 10 - 2 0 ～ 1 2 1× 10 - 14 s- 1,并随温度的升高而增大。研究结果表明 ,第四纪时期仍然存在上地幔底辟上涌 ,但其规模和活动强度均变弱     

东北地区2002年第四季度M_L≥3.0地震目录

Theearthquakes (ML≥ 3 0 )catalogueofFouthquarterinnortheasternarea ,2 0 0 2序号发　震　时　间地　　震　　位　　置月日时　分　秒北　纬东　经地　　点震级(ML)深度(km)精度110 90 9-3 8-3 4 0 48°48′ 13 0°2 9′黑龙江嘉荫 3 9822 10 12 13 -5 1-4 7 7 3 9°2 3′ 12 2°13′辽宁省普兰店 3 0 1113 10 2 5 0 5 -12 -0 5 5 40°3 6′ 12 2°5 2′辽宁省海城 3 6814 10 2 5 18-3 4-2 5 83 8°3 3′ 12 0°15′渤海 3 7 25 112 19-2 2 -3 2 5 3 8°2 2′ 12 0°2 6′黄海 3 5 26112 5 12 -2 0 -5 0 93 8°5 6′ 12 1…     

东北地区2003年第三季度ML≥3.0地震目录

序号发震时间地　震　位　置月日时　分　秒北纬东经地　点震级(ML)深度(km) 精度1 71 42 0 1 5 2 4 940°31′ 1 2 3°0 3′辽宁省海城 3 1 1 2Ⅰ2 72 4 0 2 0 2 4 2 845°5 6′ 1 30°5 0′黑龙江省勃利 3 8Ⅰ3 81 2 0 5 5 1 7 0 5 2°2 8′ 1 2 3°42′黑龙江省塔河 3 7Ⅰ4 81 80 0 331 7 437°5 7′ 1 2 0°43′渤海 3 8Ⅱ5 91 91 9482 7 5 37°48′ 1 2 4°37′黄海 3 4Ⅱ6 92 0 0 82 5 30 0 4 5°1 6′ 1 2 5°1 3′吉林省松原 3 3Ⅰ792 2 0 0 2 95 7 95 3°1 7′ 1 2 4°0 2′黑龙江省漠河 3 2Ⅰ892 2 2 0 5 90 5 0 39°42′ 1 …     

东北地区2003年第一季度ML≥3.0地震目录

Theearthquakes (ML≥ 3 0 )catalogueoffirstquarterinnortheasternarea ,2 0 0 3序号发　震　时　间地　　震　　位　　置月日时　分　秒北　纬东　经地　　点震级(ML)深度(km)精度11914 -3 9-19 63 7°48′ 12 4°49′黄海 3 6Ⅱ2 1916-3 3 -16 63 7°41′ 12 4°2 8′黄海 4 2Ⅱ3 114 19-2 9-0 8 746°3 9′ 13 2°3 6′黑龙江省宝清 3 0Ⅰ42 2 13 -4 7-0 2 3 40°3 8′ 12 2°3 7′辽宁省海城 3 113Ⅰ5 2 5 11-3 2 -11 942°3 7′ 12 5°3 9′吉林省东丰 3 0 3 3Ⅰ62 14 15 -4 2 -3 7 2 3 7°3 9′ 12 4°3 4′黄海 3 4Ⅱ72 2 …     

1999年山西省ML≥3.0地震目录

发　震　时　间震　　中　　位　　置月 -日 T时 :分 :秒φN/ (°) (′)λN/ (°) (′)地　点震　级ML深　度h/ km 精　度0 1- 16 T11:5 8:44 .0 37°14′ 112°0 2′汾阳市 3.0 10 10 1- 2 2 T0 1:11:47.0 36°15′ 111°38′洪洞县 3.0 1410 1- 2 6 T17:0 7:42 .7 35°11′ 111°5 6′垣曲县 3.2 1110 2 - 0 1T0 1:0 7:35 .6 39°5 2′ 113°44′大同县 3.45 10 2 - 0 4T0 7:14:11.837°38′ 112°31′太原市 3.110 10 4- 12 T0 0 :45 :2 3.837°0 3′ 111°5 2′介休市 3.2 1320 5 - 15 T16 :11:16 .839°2 8′ 113°2 4′应　县 4.…     

云南省2001年上半年地震活动综述

据云南数字地震台网测定 ,2 0 0 1年上半年云南省共记录到 3级以上地震 5 5次 (不含余震 ) :其中 3～ 3 9级地震 44次、 4～ 4 9级 5次、 5～ 5 9级 5次。 2 0 0 1年上半年云南地区地震活动最显著的特点是历史上少见的中强震连发 (表 1 )。表 1　云南地区 2 0 0 1年上半年 5级地震目录编号发震时间震中位置年月日农历时分秒北纬东经地名 震源深度震级ＭＬ ＭＳ精度12 0 0 1 2 19廿七 2 3-5 1-362 1°2 6′ 10 2°5 0′老挝 10ｋｍ 5 2 42 2 0 0 1 2 2 0廿八 0 3-0 2 -5 12 1°2 2′ 10 2°5 4′老挝 8ｋｍ 5 432 0 0 1 3 12十八 16-5 7…     

长白山天池火山监测站

吉林省长白山天池火山监测站是中国地震局和吉林省政府共同建设的火山监测与科研机构 ,隶属于吉林省地震局。位于 4 2°2 4′36″N ,1 2 8°0 6′2 1″W ,海拔 1 80 0m ,距天池3 5km ,占地面积 1 4 0 0m2 。1 996年 5月开始建设 ,1 998年 9月基建竣工 ,1 999年 7月监测网布设完成、监测仪器和设备投入观测 ,建成了国内先进的数字化火山地震监测系统 ,同年 1 0月 9日通过中国地震局和吉林省政府的验收。2 0 0 1年 1 2月被科技部列为国家重点野外实验站。1　基本情况长白山天池火山监测站始建于 1 996年 5月 ,1 998年 9月基本建设完成 ,占地…     

长白山火山的历史与演化

长白山火山跨越中朝两国,在我国境内包括天池火山、望天鹅火山、图们江火山和龙岗火山,火山活动从上新世持续到近代,是我国最大的第四纪火山分布区。长白山火山的母岩浆是钾质粗面玄武岩,将长白山火山岩区称钾质粗面玄武岩省,岩浆结晶分异作用和混合作用主导了岩浆演化过程。天池火山之下地壳岩浆房和地幔岩浆房具双动式喷发特点,一方面来自地幔的钾质粗厨玄武岩浆直接喷出地表;另一方面钾质粗面玄武岩浆持续补给地壳岩浆房,发生岩浆分离结晶作用和混合作用,导致双峰式火山岩分布特征和触发千年大喷发。西太平洋板块俯冲-东北亚大陆弧后引张是长白山火山活动的动力学机制。     

2000年1月15日云南省姚安县发生5.9、6.5级强震

据云南省地震遥测台网测定 :2 0 0 0年 1月 1 5日 0 6时 0 9分 0 1秒和 0 7时 37分 0 5秒分别在 2 5°34′Ｎ ,1 0 1°0 5′Ｅ ;2 5°35′Ｎ ,1 0 1°0 7′Ｅ ,距姚安县城西北约 1 0ｋｍ处先后发生了 5 9级和 6 5级两次强震 ,震源深度初定为 30ｋｍ。截至 2月 9日共记录到 1级以上地震共 463次 ,其中 1～ 1 9级 2 80次 ,2～ 2 9级 1 56次 ,3～ 3 9级1 6次 ,4～ 4 9级 7次 ,5 9、 6 5级各一次 ,最大余震为 4 7级 ,余震震中高度集中于 7× 8(ｋｍ2 )范围内。现场考察结果显示极震区长轴为Ｎ1 2°Ｅ的椭圆。极震区烈度为ＶＩＩＩ度 ,位于姚安…     

强震观测网、高灵敏度地震观测网、地中强震观测网、宽频带地震观测网

阪神·淡路大震灾后 ,日本着手对原有的地震观测体制作彻底改革 ,多项全国性配置地震计的计划同时开始启动。地震引起的地面晃动的程度不尽相同 ,无感微小地震引发的晃动仅有 0 .0 0 1 μm,频率为1 0 Hz;巨大地震引起的地面晃动的幅度高达 2～ 3 m,周期也有几十秒。虽说都称之为地震计 ,但由于地震动的振幅和频率涉及的范围太大 ,所以应针对观测对象选用不同类型的地震计。下面介绍不同类型的观测网。1　强震观测网 ( K- NET)无论大地有多大的晃动都能将其准确记录下来的地震计称之为强震计。它构造坚实 ,信号明确 ,通常设置在地表 ,对了…     

Age, geology, geophysics, and geochemistry of Mahukona Volcano, Hawai`i

The size, shape, and magmatic history of the most recently discovered shield volcano in the Hawaiian Islands, Mahukona, have been controversial. Mahukona corresponds to what was thought to be a gap in the paired sequence (Loa and Kea trends) of younger Hawaiian volcanoes (<4?Ma). Here, we present the results of marine expeditions to Mahukona where new bathymetry, sidescan sonar, gravity data, and lava samples were collected to address these controversies. Modeling of bathymetric and gravity data indicate that Mahukona is one of the smallest Hawaiian volcanoes (～6,000?km³) and that its magmatic system was not focused in a long-lived central reservoir like most other Hawaiian volcanoes. This lack of a long-lived magmatic reservoir is reflected by the absence of a central residual gravity high and the random distribution of cones on Mahukona Volcano. Our reconstructed subsidence history for Mahukona suggests it grew to at least ～270?m below sea level but probably did not form an island. New ⁴⁰Ar–³⁹Ar plateau ages range from 350 to 654?ka providing temporal constraints for Mahukona’s post-shield and shield stages of volcanism, which ended prematurely. Mahukona post-shield lavas have high ³He/⁴He ratios (16–21?Ra), which have not been observed in post-shield lavas from other Hawaiian volcanoes. Lava compositions range widely at Mahukona, including Pb isotopic values that straddle the boundary between Kea and Loa sequences of volcanoes. The compositional diversity of Mahukona lavas may be related to its relatively small size (less extensive melting) and the absence of a central magma reservoir where magmas would have been homogenized.     

The Yecheng,Xinjiang, China,earthquake of February 14, 1980

In this study, we have checked the location and focal depth of the Yecheng earthquake (m _b = 6.0, maximum intensity VII) of February 14, 1980. The result shows that this is an intermediate event with a focal depth of 90 km. The microepicenter is located at 36. 4°N, 76, 9°E, while the macroepicenter is at 37.3°N, 76.9°E, 90 km to the north of the microepicenter. This is the first destructive intermediate event in China which led to a damage as severe as of intensity VII. The focal mechanism of the event is determined to be of thrust type. Combined with the analysis of seismological and geological data in surrounding area, the possible relation between the event and plate movement has been discussed. The result in this paper indicates that in some particular place, the destructive effect of intermediate event should be considered in seismic hazard assessment.     

Physical properties,vitrinite reflectance,and microstructure of coal,Taiyuan Formation,Qinshui Basin,China

In this study, we experimentally established the relationship between physical properties, vitrinite reflectance, and microstructure of coal, Taiyuan Formation, Qinshui Basin, China using representative coal samples collected from three different mines via the rock mechanics testing system (MTS). We analyzed the organic macerals, vitrinite reflectance, and microstructure of 11 coal samples using petrography and scanning electron microscopy (SEM). The experimental results suggest that (1) the elastic parameters can be described by linear equations, (2) both P-and S-wave velocities display anisotropy, (3) the anisotropy negatively correlates with vitrinite reflectance, and (4) the acoustic velocities and Young’s modulus are negatively correlated with the volume of micropores. The derived empirical equations can be used in the forward modeling and seismic inversion of physical properties of coal for improving the coal-bed methane (CBM) reservoir characterization.     

Spatial distribution,source apportionment,and associated risks of trace metals (As,Pb, Cr,Cd, and Hg) from a subtropical river,Gomti, Bangladesh

Sediment samples from the Gomti River basin were investigated to determine and evaluate trace metal concentrations,their biological effect,and potential ecological and human health risks for adults and children.The mean concentrations of trace metals were organized in the descending order of mercury(Hg)(0.08 mg/kg)>chromium(Cr)(0.06 mg/kg)>lead(Pb)(0.05 mg/kg)>arsenic(As)(0.02 mg/kg)>cadmium(Cd)(0.01 mg/kg).The current study illustrated that metals were attributed to the area from natural sources and different anthropogenic sources especially from industries.However,the concentration levels were lower than the sediment quality guidelines(SQGs)based on the effect-range classifications of threshold effect concentration(TEC)and probable effect concentration(PEC).Therefore,the concentration of the elements showed no adverse biological effects on aquatic organisms.The evaluated potential ecological risk index also revealed the low toxicity to the aquatic environment.Moreover,the applied sediment quality indices,geo-accumulation index(Igeo),contamination factor(CF),and contamination severity index(CSI)suggested that the contamination levels of the elements were in the acceptable range,and the contamination had not notably impacted on the sediment quality.The risk index(HI)concerning age groups was significantly less than the threshold limit of 1 indicating that the contamination had no non-carcinogenic risk effect.The total carcinogenic risk(TCR)was less than a risk value of 1×10⁴.Hence,the current study suggests that immediate remediation is not required due to an absence of alarming conditions in the study area.Proper monitoring of the attribution of the metal elements should be done for the betterment of human and environmental health。     

Sun, climate, hunger, and mass migration

Paleoclimatic studies indicate four epochs of global cooling during the last 4 000 years, i. e. during the few centuries before and after 2000 BC, 800 BC, 400 AD, and 1 600 AD; the quasiperiodicity corresponds to cyclic variation of solar activity. Global temperature changes influenced regional precipitation patterns: Northern Europe was wetter while the middle- and low-latitude lands were more arid during colder epochs. Both sets of cold climatical conditions were unfavorable for agricultural production. Historical records show that large demographic movements in history took place because of crop failures and mass starvation, rather than escaping from war zones. The “wandering” of the Germanic tribes during the first two or three centuries of the Christian Era is one example. Whereas the accelerated release of carbon dioxide from the burning of fossil fuels is ultimately to cause global warming, historical evidence indicates, however, that global warming has been on the whole a blessing to mankind. Global cooling, on the other hand, has curtailed agricultural production and has led to famines and mass migrations of people. Perhaps the most important task at the present is not so much computer-modelling of greenhouse effect on global climate, but water-management and agricultural researches to insure food-supply for an everincreasing world population.