美国地震学者在成都讲学要点摘编

美国加州大学伯克利分校地球科学系秦建业博士、康奈尔大学地质科学系纳尔逊博士和加州“数字研究”软件公司赛兹女士在1984年6月国际喜马拉雅地质科学讨论会结束后应邀到成都地质学院和四川省地震局进行学术交流和讲学活动。他们分别介绍了:①美国加州大学伯克利分校地球科学系教学科研概况;②用纯途径的雷利波和洛夫波群速度研究西藏高原地壳的最新成果;③美国内华达州地下核试验基地的地壳结构;④美国大陆反射剖面联合会工作的进展;⑤关于微机软件最近的发展。本文对他们上述的这些讲学要点作了摘编。     

俄罗斯地震学者马沙尔斯基一行三人来辽宁局访问

1992年10月23日,俄罗斯西伯利亚科学分院大地地壳研究所(即原“АКАДЕМИЯНАУКСССРСИБИРСКОЕОТДЕЛЕНИЕИНСТИТУТЗЕМНОЙКОРЫ”)马沙尔斯基(地震队队长)索洛年科、如里科三位地震学者来我局访问。局总工程师全莹道副研究员和辽宁省地震研究所所长钟以章副研究员接见了俄罗斯三位学者。宾主在友好诚挚的气氛中,对地震科学技术发展进行了广泛的交流。应俄罗斯客     

(美)J.Fr:day 先生来石访问讲学

应河北省地震局邀请,美国加利福尼亚大学伯克利地震台J.Friday先生于5月22日至5月30日来华访问讲学。Friday先生擅长于计算机系统工程,是数字地震信号12集处理方面的专家,为伯克利数字化地震占网的研制和建设做出了卓有成就的贡献。     

美国Ressenlaer大学斯蒂文教授来新疆讲学──关于天山地壳动力学研究

美国Ressenlaer大学斯蒂文教授于1996年10月18日上午来新疆维吾尔自治区地震局讲学。主讲内容为天山地壳动力学研究。天山是板块内的造山带，有其独特的研究意义。亚欧板块与印度洋板块汇聚后产生的强烈的挤压作用使地壳大大缩短，同时也造成地慢变化，形成山根或地慢下坠。山前地带广泛发育俯冲断裂运动，地慢对流往下循回，构造线走向与板块冲撞力相垂直。在吉尔吉斯斯坦境内工作时，见到由古生代语皱形成的天山被中生代和早新生代地层覆盖。全球卫星定位系统观测到阔克萨勒岭山系以北地区最大上升速率为13土2m而／。；用地质和地球物理…     

SEDIMENT DAMAGES AND RECENT TRENDS IN THE UNITED STATES

lINTRODUCTIONWeoftenhavethepercepti0nthatsedimentisthebr0wnishoryell0wishcoloringinrunoffwater,thatlooksunpleasant,buteventually"g0esaway,"downstream,unseen.Butsedimentisn0tonlyaestheticallyunpleasant,itisalsoacarrierofpotentialchemicalc0ntaminants,fillsupwaterb0dies,andcausesphysicaldamaget0farmland,wildlife,andwatertreatmentsystemsandpowergenefat0rs.ThepurposeofthispaPeristoprovidean0verallperspectiveonthemagnitudeandtrendsofsedimelltasap0llutritintheUnitedStates.2CURRENTKNOWLEDG…     

中美两国的地裂缝灾害

无震地裂现象常与地面沉降相伴生,在中国的7个省、美国的6个州致灾严重．中国现代地裂灾害观察研究滞后于美国约半个世纪．两国地裂的形成、演化、致灾及对策诸方面的对比研究表明,地裂灾害属自然与人类活动因素相叠加而引起的环境地质灾害．构造因素决定了地裂出现的位置,而人类活动因素,即过量开采地下水、石油等,决定了地裂致灾的强度．因而,相应的减灾措施既有科学技术方面的,也有社会管理方面的．本文给出的两国减灾实例可供参考．     

EFFECTS OF CLIMATE CHANGE ON FRESHWATER ECOSYSTEMS OF THE SOUTH-EASTERN UNITED STATES AND THE GULF COAST OF MEXICO

The south-eastern United States and Gulf Coast of Mexico is physiographically diverse, although dominated by a broad coastal plain. Much of the region has a humid, warm temperate climate with little seasonality in precipitation but strong seasonality in runoff owing to high rates of summer evapotranspiration. The climate of southern Florida and eastern Mexico is subtropical with a distinct summer wet season and winter dry season. Regional climate models suggest that climate change resulting from a doubling of the pre-industrial levels of atmospheric CO₂ may increase annual air temperatures by 3–4°C. Changes in precipitation are highly uncertain, but the most probable scenario shows higher levels over all but the northern, interior portions of the region, with increases primarily occurring in summer and occurring as more intense or clustered storms. Despite the increases in precipitation, runoff is likely to decline over much of the region owing to increases in evapotranspiration exceeding increases in precipitation. Only in Florida and the Gulf Coast areas of the US and Mexico are precipitation increases likely to exceed evapotranspiration increases, producing an increase in runoff. However, increases in storm intensity and clustering are likely to result in more extreme hydrographs, with larger peaks in flow but lower baseflows and longer periods of drought. The ecological effects of climate change on freshwaters of the region include: (1) a general increase in rates of primary production, organic matter decomposition and nutrient cycling as a result of higher temperatures and longer growing seasons: (2) reduction in habitat for cool water species, particularly fish and macroinvertebrates in Appalachian streams; (3) reduction in water quality and in suitable habitat in summer owing to lower baseflows and intensification of the temperature–dissolved oxygen squeeze in many rivers and reservoirs; (4) reduction in organic matter storage and loss of organisms during more intense flushing events in some streams and wetlands; (5) shorter periods of inundation of riparian wetlands and greater drying of wetland soils, particularly in northern and inland areas; (6) expansion of subtropical species northwards, including several non-native nuisance species currently confined to southern Florida; (7) expansion of wetlands in Florida and coastal Mexico, but increase in eutrophication of Florida lakes as a result of greater runoff from urban and agricultural areas; and (8) changes in the flushing rate of estuaries that would alter their salinity regimes, stratification and water quality as well as influence productivity in the Gulf of Mexico. Many of the expected climate change effects will exacerbate current anthropogenic stresses on the region's freshwater systems, including increasing demands for water, increasing waste heat loadings and land use changes that alter the quantity and quality of runoff to streams and reservoirs. Research is needed especially in several critical areas: long-term monitoring of key hydrological, chemical and biological properties (particularly water balances in small, forested catchments and temperature-sensitive species); experimental studies of the effects of warming on organisms and ecosystem processes under realistic conditions (e.g. in situ heating experiments); studies of the effects of natural hydrological variation on biological communities; and assessment of the effects of water management activities on organisms and ecosystem processes, including development and testing of management and restoration strategies designed to counteract changes in climate. © 1997 John Wiley & Sons, Ltd.     

DISTRIBUTION OF RIVER BASIN AREA IN THE CONTERMINOUS UNITED STATES

Abstract

The number of sub-basins of any given area (a), within any given basin or region of area (A) is well approximated by the formula

Na = 0.28 A/a

for values of A/a larger than 10. The standard error of values predicted by this formula is 25 percent. When the number of stations at which stream gaging is performed is compared with the total number of watersheds of various sizes in the continental United States, it becomes evident that there is a serious undersampling of small streams and an excess gaging of large rivers.     

美国爱达荷州中部洛斯特河断层麦凯段晚第四纪断层陡坎与地震

根据断层位错和地貌位置,麦凯段断层陡坎分为三组,它们是三次史前地震的产物。根据位错量和陡坎长度对比,史前地震的震级大约为7级。利用扩散方程模拟史前7级地震发生的重复时间间隔是5—11千年     

COMPARISON OF SEDIMENT DISCHARGE PREDICTIONS FOR SMALL WATERSREDS IN THE SOUTRWESTERN UNITED STATES

ＣＯＭＰＡＲＩＳＯＮ　ＯＦ　ＳＥＤＩＭＥＮＴ　ＤＩＳＣＨＡＲＧＥ　ＰＲＥＤＩＣＴＩＯＮＳ　ＦＯＲ　ＳＭＡＬＬ　ＷＡＴＥＲＳＲＥＤＳ　ＩＮ　ＴＨＥ　ＳＯＵＴＲＷＥＳＴＥＲＮ　ＵＮＩＴＥＤ　ＳＴＡＴＥＳＹａｋｏｖＷＩＧＤＯＲ；ＶｉｃｅｎｔｅＬ．ＬＯＰＥＳ...