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北京时间2022年6月10日1时28分四川阿坝州马尔康市(32.25°N,101.82°E)发生6.0级地震。中国地震台网中心于震后3min发布自动速报结果、震后约7min发布正式速报结果,同时联合多家单位启动地震应急产品产出工作,共产出震源参数、历史地震、地质构造、震源机制、余震精定位、推测烈度和震源破裂过程等9类应急产品,对于发震断层的孕震构造给出了初步约束。结果显示,本次地震发生在松岗断裂附近,位于青藏高原巴颜喀拉块体东部的阿坝次级地块;震源机制解表明该地震是一次走滑型事件,余震与主震性质整体一致。余震烈度速报推测极震区烈度达Ⅸ度,区域面积约70km2;Ⅷ度及以上区域面积约734km2,涉及7个乡。 相似文献
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Xueyuan Kuang Yaocun Zhang Ying Huang Danqing Huang 《Theoretical and Applied Climatology》2014,117(1-2):103-112
NCEP/NCAR reanalysis daily data from 1951 to 2008 are used in this study to reveal the spatial-asymmetric features in the seasonal variation of the upper-tropospheric jet stream (UTJS) and its thermal dynamic forcing mechanism. The jet occurrence percentage distribution of the UTJS demonstrates a spiral-like pattern in winter, but it is quasi-annular in summer. The jet occurrence percentage in the Eastern Hemisphere is larger than that in the Western Hemisphere, and its maximum area is located further south. The polar front jet stream (PJS) and subtropical jet stream (SJS) can be distinguished over the Northern Africa and Asian regions, whereas only one jet stream can be observed over the Western Pacific and Atlantic Ocean. Furthermore, a single peak pattern is found in the seasonal variation of the SJS occurrence frequency with the highest jet occurrence appearing in winter and the lowest in summer, while a double peak pattern is observed in the seasonal variation of the PJS occurrence, i.e., the jet occurrence reaches its peaks in autumn and spring for the PJS. Based on the thermal wind theory, air temperature gradient and atmospheric baroclinicity are calculated and compared with the jet occurrence variation to explore the thermal dynamic forcing mechanism for the UTJS variation. In addition, synoptic-scale transports of eddy heat and momentum are also calculated. The results indicate that the SJS variation is primarily determined by the air temperature gradient and atmospheric baroclinicity, while the PJS variation is under great influence of the transport of eddy heat and momentum over Northern Africa and East Asia. The UTJS variation over the area from 140E to 70W cannot be well individually explained by the air temperature gradient and atmospheric baroclinicity. Further analysis indicates that UTJS variation over this area is largely under control of combined effect of the transport of eddy heat and momentum as well as the atmospheric baroclinicity. 相似文献
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Observations on the morphology of embryonic and larval development in Styela canopus Savigny 总被引:2,自引:0,他引:2
INTRODUCTIONAscidians,commonmarinefoulingorganisms,containmanycompoundswithbiologicalactivitiesagainsttumourandbacteria .Thelarvaofascidianhasanotochordwhichdegeneratesafterthemetamorphosis .Thenotochordistheprototypeofvertebraeofhigheranimals,ascidi anshavespecialsignificancesinanimalevolutionandclassification .Thereforethestudyofas cidiansalwaysattractsbiologistsattention .Asfarasresearchesofascidiansareconcerned ,theclassification ,distribution ,physiologyandchemicalconstituentsinascid… 相似文献
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Settlement and metamorphosis of Styela canopus Savigny larvae in response to some neurotransmitters and thyroxin 总被引:2,自引:0,他引:2
1IntroductionAs importantsteps in the life cycles of mostma-rine benthos,settlement and metamorphosis of theirplanktonic larvae influence directly the populationdistribution and fluctuation of benthos.Research onlarval settlement and metamorphosis of mari… 相似文献
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Natural Hazards - Loess–mudstone landslides are widely distributed in Northwest China. However, the deformation features and kinematic processes of these landslides are still not well... 相似文献
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Trophic relationships in the Changjiang River estuarine salt marshes: preliminary investigation from δ13C and δ15N analysis 总被引:1,自引:0,他引:1
QUAN Weimin HUANG Danqing CHU Tianjiang SHENG Qiang FU Cuizhang CHEN Jiakuan WU Jihua 《海洋学报(英文版)》2009,28(3):50-58
To obtain information on food web structure in salt marshes of the Changjiang (Yangtze) River Estuary, the δ13C and δ15N values of primary producers and consumers were determined. The mean δ13C values of 31 dominant consumers ranged from -23.13‰ to -14.37‰. Except for several species (Eriocheir sinensis, Sinonovacula constricta and Potamocorbula ustulata), consumers had intermediate δ13C values between those of benthic microalgae and Spartina alterniflora. The mean δ15N values of 31 dominant consumers varie... 相似文献
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高植被覆盖区遥感矿化蚀变信息提取结果会受植被覆盖影响其效果。笔者基于西秦岭大桥-石峡地区,利用ETM和Aster影像数据,进行高植被覆盖区遥感矿化蚀变信息提取研究,探讨抑制植被干扰和提取遥感矿化蚀变信息的方法,提出了多元数据叠加分析法。采用"混合像元法剔除干扰+多层次分离技术分析波段相关关系+多元数据叠加分析法增强蚀变信息+正态分布阈值分割法分级提取"等系列方法,提取了研究区遥感铁染和羟基异常,其中铁染异常区占研究区面积1.63%,羟基异常区占研究区面积1.26%。矿床点与遥感异常相关比率为45.5%,说明该方法在高植被覆盖区提取遥感矿化蚀变信息效果较好,具有一定示矿意义。 相似文献
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Changes of temperature extremes over China were evaluated using daily
maximum and minimum temperature data from 591 stations for the period
1961--2002. A set of indices of warm extremes, cold extremes and daily
temperature range (DTR) extremes was studied with a focus on trends. The
results showed that the frequency of warm extremes (F_WE) increased
obviously in most parts of China, and the intensity of warm extremes
(I_WE) increased significantly in northern China. The opposite
distribution was found in the frequency and intensity of cold extremes. The
frequency of high DTR extremes was relatively uniform with that of
intensity: an obvious increasing trend was located over western China and
the east coast, while significant decreases occurred in central,
southeastern and northeastern China; the opposite distribution was found for
low DTR extreme days. Seasonal trends illustrated that both F_WE and
I_WE showed significant increasing trends, especially over northeastern
China and along the Yangtze Valley basin in spring and winter. A correlation
technique was used to link extreme temperature anomalies over China with
global temperature anomalies. Three key regions were identified, as follows:
northeastern China and its coastal areas, the high-latitude regions above
40oN, and southwestern China and the equatorial eastern Pacific. 相似文献