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921.
台湾海峡地震与地质构造,地壳运动的关系 总被引:2,自引:2,他引:2
在我国辽阔的渤海、黄海、东海和南海,只有渤海发生过Ms≥7级地震。而面积狭小的台湾海峡却发生3次7-8级地震、34次5-6.9级地震,是我国大陆邻近海域地震活动强度最大、频度最高的地方。 相似文献
922.
利用重矿物含量和河品地貌特征,推测近岸区沉积物沿岸运移,由海湾中部向两侧方向并随季节而变化,泥沙净位称方向由NE至SW。 相似文献
923.
台风Maggie(9903)的移动路径属于历史上罕见的疑难路径之一,在1999年6月6日0时(UTC,下同),台风位于22.3°N,119.8°E附近,它向西北方向移动,于6月6日12时抵达广东汕尾附近海面,然后沿海岸线折向西南行,于6月7日下午到达阳江附近海面,经历一次360°的打转后再折向北行在阳江登陆,澳门地球物理暨气象局以MM5为基础的台风数值预报试验系统在6月6日0时相当准确地报出Maggie的未来48h移动路径和降水,敏感性试验说明,华南大陆的海岸线走向和地形对Maggie的移动路径无明显的影响,它之所以沿海岸线折向西南行应是其环境场改变的结果,把华南陆地变为海洋后,Maggie在向西南移动过程中继续发展,这说明,当台风接近陆地或登陆后,陆面摩擦和下垫面水气供应的减少是引起台风减弱的主要因子。 相似文献
924.
中国第四纪地质发展史 总被引:4,自引:1,他引:4
张宗祜 《海洋地质与第四纪地质》1991,11(2):1-6
中国大陆第四纪地质发展史的决定性因素是以青藏高原抬升为主的新构造运动,干冷—温暖频繁交替的古气候变化。中国第四纪时期内发生过一系列重大的地质事件:强烈的新构造活动及青藏高原的抬升;频繁的冷暖交替的气候变化;第三纪末以来古湖泊的萎缩和消亡及大陆外流型水系的形成;活跃的火山活动;巨厚黄土的堆积;第四纪大沙漠的形成和发展。 相似文献
925.
Numerical prediction experiment on Typhoon Maggie (9903) 总被引:3,自引:1,他引:3
Fong Soi Kun Wu Chisheng Hao I Pan Lam Kin Hang Ku Chi Meng Wang Anyu Lin Wenshi 《海洋学报(英文版)》2001,20(2):171-181
I~IOXTyphoon is a severe and diSaStrous weather phenomenon that affeCts the southeaSt COaStsregion of China. It causes Serious lOSS for the social eCOnondc development as well as the life andproperties Of PeOPle. Therefore, the enhancement to study on the artifice of monitoring, Prediction and public services of typhoon is an i~nent requirement for gove~t and Public.The concern is also a taSk of great Urgency to advanCe meteorolQgical sciences.Starting from the 1980' s, as the deve… 相似文献
926.
针对因矿区地表地形复杂而导致的传统测量施测有困难的问题,探讨了三角高程测量对向观测法和RTK在此种情况下的适用性。结果表明:三角高程对向观测方法能满足四等水准测量限差要求,可以替代四等水准测量,适用于复杂矿区地表沉降变形监测的日常观测;RTK实时动态测量技术精度符合平面测量要求。 相似文献
927.
Tawanda W. Gara Tiejun Wang Andrew K. Skidmore Shadrack M. Ngene Timothy Dube Mbulisi Sibanda 《国际地球制图》2017,32(11):1243-1253
Understanding factors affecting the behaviour and movement patterns of the African elephant is important for wildlife conservation, especially in increasingly human-dominated savanna landscapes. Currently, knowledge on how landscape fragmentation and vegetation productivity affect elephant speed of movement remains poorly understood. In this study, we tested whether landscape fragmentation and vegetation productivity explains elephant speed of movement in the Amboseli ecosystem in Kenya. We used GPS collar data from five elephants to quantify elephant speed of movement for three seasons (wet, dry and transitional). We then used multiple regression to model the relationship between speed of movement and landscape fragmentation, as well as vegetation productivity for each season. Results of this study demonstrate that landscape fragmentation and vegetation productivity predicted elephant speed of movement poorly (R2 < 0.4) when used as solitary covariates. However, a combination of the covariates significantly (p < 0.05) explained variance in elephant speed of movement with improved R2 values of 0.69, 0.45, 0.47 for wet, transition and dry seasons, respectively. 相似文献
928.
Regionalcharacteristicsofstressfieldinthesouthernpartofthenorth-southseismicbeltinChinaanditsrelationwithplate movementJi-Ren... 相似文献
929.
The Nullarbor Plain is the largest karst area in Australia (220,000 km2) and one of the largest in the world. Its climate is arid (Köppen BWk and BWh), and the surface relief is less than 10m. The landscape is divided into extensive closed karstic depressions separated by low rocky ridges, and the dominant vegetation is chenopod shrubland. The extent and severity of soil degradation has been assessed using remote sensing. GPS rectified images from 1972–1973, 1979, 1983, 1988, and 1991 have been compared for two sites on the Nullarbor. Over the 19 years the total extent of bare soil has reduced significantly, but some areas around water points have degraded and there is some disturbance due to fossorial wombats. Sheet-flow processes occur during intense rainfall events, which happen two or three times per decade. Runoff only occurs after the 10– or 50– year return frequency events, and at these times turbid water ponds in depressions and enters caves. Surface soil sorptivity and hydraulic conductivity differ markedly between ridges and depressions; the ridges are clearly zones of groundwater recharge, while ponding is evident in most depressions. Sorptivity is influenced by the extent and nature of ground cover and cryptogam crusts on the soil. The landscape has been divided into classes on the basis of vegetation type and percentage of foliage cover. In each class the activities of fallout radionuclides will be determined by high resolution spectroscopy. Preliminary results suggest that in undisturbed sites little sediment movement has occurred over the time scale of cesium-137 (the last 35 years) but that the landscape has been well sorted over a much longer time scale. Future work will investigate disturbed sites to estimate relative soil loss during the pastoral period. 相似文献
930.