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31.
福建省地震重点视防御区城市防震减灾体系工程以中国地震局关于建立健全地震监测预报、震灾预防和紧急救援三大体系为主要目标 ,以国家和福建省确定的地震重点监视防御区为主要目标区 ,尤以切实加强重点监视防御内城市的防震减灾措施 ,强化城市对地震灾害的综合防御能力为主要建设内容。该项目得到中国地震局、福建省委、省政府和有关地市大力支持 ,已列为福建省“十五”重点项目 ,省委、省政府为民办实事重点项目 相似文献
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青藏高原西北缘高原面与陡坡地貌形成过程的裂变径迹热年代学约束 总被引:9,自引:1,他引:9
对青藏高原西北缘高原内部和陡坡地貌带2个花岗岩体10件磷灰石裂变径迹年龄测定表明,高原内部大红柳滩—郭扎错逆冲断裂上盘磷灰石裂变径迹年龄为24.8±4.9~14.0±1.3Ma,此外,一个玄武岩烘烤的热事件年龄为7.9±0.8Ma;而陡坡地貌带的西昆仑中间逆冲断裂上盘的磷灰石裂变径迹年龄为2.9±0.5~0.9±0.3Ma。进一步的热历史模拟结果显示,高原内部自渐新世以来经历了2期隆升-剥露,分别是渐新世—早中新世(30~16Ma)和上新世以来(≤5Ma),而陡坡带只记录了晚中新世以来(≤8Ma)的隆升-剥露,暗示他们经历了不同的热演化历史。结合前人在该区的磷灰石裂变径迹年龄数据和野外地质现象,认为现今高原边缘陡坡地貌带可能是自晚中新世以来(≤8Ma)高原边界断裂伴有向塔里木盆地后展式叠瓦逆冲产生的构造抬升的结果;现今高原面有可能是由高原边界断裂系于大约5~2Ma以来强烈活动逐渐形成的,其隆升-剥蚀幅度>2000~3000m。这对自晚中新世以来青藏高原西北缘高原面与陡坡地貌形成过程提供了磷灰石裂变径迹热年代的重要约束。 相似文献
33.
Bimal Kanti Paul 《The Professional geographer》1998,50(3):287-301
On May 13, 1996, a disastrous tornado hit the Tangail district of Bangladesh, killing more than 700 people and causing extensive damage to homes, crops, and livestock. This paper explores and analyzes how tornado victims adjusted to this destruction. Data collected from two study sites show that victims received emergency assistance from people both in neighboring areas and from more distant areas, as well as from government agencies and non-governmental organizations (NGOs). At both sites, NGOs played the leading role in minimizing the hardships of victims through extraordinary disaster relief and rehabilitation efforts. Because of the extensive support received, the tornado victims were able to return to their “normal” lives very quickly. This study concludes with several recommendations to help cope with future tornado disasters. 相似文献
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青藏高原西北缘盆山过渡带陡坡地貌的形成时代与成因 总被引:1,自引:0,他引:1
平均海拔大于4500 m的青藏高原,是通过高原边缘的陡坡地貌与海拔低于1500 m的周缘盆地或平原相连接的,这些围绕高原的陡坡地貌是何时、如何形成的呢?本文通过对西昆仑山中段北缘主逆冲断层上盘陡坡地貌区9件磷灰石样品的裂变径迹年龄与长度分析表明:在海拔3900~4635 m的陡坡地貌中的裂变径迹样品年龄为6.2±1.4 Ma~0.9±0.3 Ma,呈现“上新下老”的反序分布特征; 而通过热历史模拟显示约5 Ma,约3~2 Ma,约2~1 Ma 和约1 Ma该地区出现多阶段的隆升与剥露。结合前人研究成果和野外地质的观察认为,现今青藏高原西北缘陡坡地貌的形成是中新世晚期以来高原边界叠瓦状断裂系经历了约8 Ma、约5 Ma、约3~2 Ma、约2~1 Ma和约1 Ma多阶段后展式逆冲运动的结果,这为青藏高原周缘陡坡地貌的形成和青藏高原的隆升时代与型式提供了关键的热年代学约束。 相似文献
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37.
Lunar landforms are the results of geological and geomorphic processes on the lunar surface. It is very important to identify the types of lunar landforms. Geomorphology is the scientific study of the origin and evolution of morphological landforms on planetary surfaces. Elevation and relief amplitude are the most commonly used geomorphic indices in geomorphological classification studies. Previous studies have determined the elevation classification criteria of the lunar surface. In this paper, we focus on the classification criteria of the topographic relief amplitude of the lunar surface. To estimate the optimal window for calculating the relief amplitude of the lunar surface, we use the mean change-point method based on LOLA (Lunar Orbiter Laser Altimeter) Digital Elevation Model (DEM) data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera (SELENE TC). The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar landforms. Taking the topographic relief amplitudes of 100 m, 200 m, 300 m, 700 m, 1500 m and 2500 m as thresholds, the lunar surface is divided into seven geomorphic types, including minor microrelief plains (< 100 m), minor microrelief platforms [100 m, 200 m), microrelief landforms [200 m, 300 m), small relief landforms [300 m, 700 m), medium relief landforms [700 m, 1500 m), large relief landforms [1500 m, 2500 m) and extremely large relief landforms (≥ 2500 m). The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins, while the minor microrelief platforms are mainly in the transition regions between the maria and highlands. The microrelief landforms are mainly located in regions with relatively high topography, such as wrinkle ridges and sinuous rilles in the mare. The small relief landforms are mainly scattered in the central peak and floor fractures of craters. The medium relief landforms are mainly distributed in the transition regions between crater floors and crater walls, between crater walls and crater rims, between basin floors and basin walls, and between basin walls and basin rims. Large and extremely large relief landforms are mainly found along crater walls and basin walls. The classification criteria determination for assessing lunar surface relief amplitude described in this paper can provide important references for the construction of digital lunar surface geomorphology classification schemes. 相似文献
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39.
Palaeosurfaces in central West Greenland as reference for identification of tectonic movements and estimation of erosion 总被引:6,自引:2,他引:4
Landform analysis of basement rocks has been undertaken with the aid of digital elevation data, aerial photographs and field observations in central West Greenland (69°15′N–66°00′N). Palaeosurfaces have been identified, dated relatively to each other, used to quantify uplift and fault movements and also used to estimate differential erosion. Two types of palaeosurfaces were mapped across the Precambrian basement: a surface at low elevation with distinct hills (hilly relief), and two planation surfaces formed across different types of basement rocks. The hilly relief surface emerges as an inclined surface from Cretaceous cover rocks in Disko Bugt and is interpreted as a stripped late Mesozoic etch surface. This surface is cut off towards the south by a less inclined planation surface, which is younger and thus of Cenozoic age. It is similar to the post-Eocene (Miocene?) planation surfaces identified on Disko and Nuussuaq in other studies. The planation surface splits in two southwards towards high areas around Nordre Isortoq and Sukkertoppen Ice Cap. The upper planation surface forms near-summit areas of tectonic blocks dipping in different directions and with different tilts. The uplift centres define the crests of two mega blocks, separated by the ‘Sisimiut Line’ which coincides with the Precambrian Ikertôq thrust zone. A partially developed lower planation surface indicates a first uplift of maximum 500 m followed by a second uplift of maximum 1000 m. We infer that these uplift events occurred during the late Neogene based on correlation with similar surfaces on Nuussuaq and the timing of exhumational events estimated from apatite fission track analyses of samples from a deep borehole on Nuussuaq (reported elsewhere). The difference between a reconstruction of the upper planation surface across the entire area and the present topography was used as an estimate of erosion of basement rock since the formation of the upper planation surface. The erosion is unevenly distributed and varies from almost none on the well-preserved planation surfaces to 800–1300 m along valleys, and even more in the fjords. Erosion is less within areas of gneiss in granulite facies, than in areas of gneiss in amphibolite facies. 相似文献
40.