中国西北黄土地区地震崩滑的分布与宏观影响因素

在中国黄土高原划分了9个震害区,分析研究了中国西北黄土地区地震崩滑的分布与宏观影响因素。研究结果认为,位于六盘山西侧、会宁以东的第4区地震崩滑最发育;可以产生黄土地震崩滑的最大震中距或区域最大面积都与震级有关;影响黄土地区地震崩滑敏感性的宏观因素包括活动地质构造、地震断层、地层、地形、水文条件、地震强度等。坡度>2°的黄土斜坡就有可能发生地震滑坡,高烈度可以削弱或消除微地形对地震滑坡的影响。与现代地形具有相似性的埋藏地形、高达黏土层或砂层的地下水位、新黄土地层等,可加重地震滑坡的发育;而一定位置的下更新统砾岩层、老黄土等则可起到抗滑作用。中国西北黄土地区产生地震崩落、滑移的最低震级分别为4、5级,或地震烈度5度。在第4震害区,烈度6～7度就可能产生明显的地震崩滑;10度以上可形成较大面积的崩滑群;7(1/2)、8级以上的地震可分别产生滑陷、流滑。多因素组合对滑坡的影响可能不同于单因素,但比单因素更重要。     

中国天山积雪雪崩站区的地理环境

中国天山积雪雪崩站站区自然地理垂直地带完整。降水丰富，最大达１１４０．８ｍｍ。冬半年降雪量占年降水量的３０％左右。积雪深度多年平均８０ｃｍ。深厚的积雪使站区每年冬季都发生雪崩和风吹雪灾害，成为天山大陆性雪崩研究的天然场所。同时，站区生态与环境良好，植被、土壤种类集天山之大成。站区旅游资源引人入胜。北有“东方阿尔卑斯”之称的乔尔马；南有巴音布鲁克天鹅湖，均由天山公路与本站相连通。     

On probabilities of avalanches triggered by alpine skiers. An empirically driven decision strategy for backcountry skiers based on these probabilities

Most fatal avalanche accidents in the Alps are caused by skiers and snowboarders. It has been one aim from the beginning to give guidelines for backcountry skiers in order to avoid avalanche accidents. About 10 years ago, the mountain guide Werner Munter developed a strategy for backcountry skiers whether to go or not to go on a skiing tour. However, his decision strategy has a lack of empirical evidence because he does not take into account incidents without avalanche accidents. This article proposes a decision strategy for backcountry skiers based on probabilities of a logistic regression model using variables, such as danger level, incline of the slope and aspect of the slope, which turned out to be the most important ones. Additional information on frequencies of skiers on slopes under specific conditions is included in the model. We used accident data and avalanche forecasts in Tyrol reported by the Tyrolean avalanche information service within three seasons (1999–2002, 497 days of observations) for model building. Additionally we carried out a holdout validation using data of the same type within two seasons (2002–2004, 314 days of observation) in order to check the accuracy of the model. Our proposal shows a remarkable correlation with Munter’s method.     

Pliocene lahar deposits in the Coastal Cordillera of central Chile: Implications for uplift, avalanche deposits, and porphyry copper systems in the Main Andean Cordillera

Lahar deposits occur within a shallow marine sedimentary succession of the Pliocene La Cueva Formation in the Coastal Cordillera of central Chile (33°40′–34°15′S). Provenance studies of the abundant volcanic material in the lahar deposits suggest that they derive from denudation by mass wasting of Oligocene–Miocene volcanic rocks on the western slopes of the Main Andean Cordillera at the same latitude. Pliocene rock debris deposits preserved in the region of El Teniente (34°S) and scattered along the westernmost part of the Andes of central Chile indicate catastrophic erosive events related to the rapid uplift of the cordilleran block. This rock debris was deposited by avalanches and transformed further downslope into lahars by dilution with stream water. Lahars were channeled along the ancient drainage system that reached a shallow Pliocene sea at the site of the present Coastal Cordillera. The exceedingly rapid exhumation of active porphyry systems during the Early Pliocene in this part of the Andes may have played a role in affecting hydrothermal processes, brecciation, and diatreme formation at the porphyry systems of El Teniente and Río Blanco–Los Bronces.     

High speed photon-counting imager using a position sensitive diode

A new use for a 2-dimensional position sensitive diode (PSD) is described. A duolateral PSD was used with a microchannel plate image intensifier as a proof-of-concept photon counting (event driven) imager for astronomical imaging and photometry. This produced an imager capable of counting 25–30 kcps over the astronomical bands B, V & R, with an overall efficiency of ∼19%.     

获取高质量激光观测数据方法

对长期人卫激光测距的实践工作的总结,并经过对实际观测结果的分析和对比,得出的正确获得卫星观测数据要求和方法,以此说明如何才能更好的收到每一卫星通过和合格数据     

The geormorphology of subalpine snow avalanche runout zones: San juan mountains,colorado

A comparison was made between the distal ends of twenty-two avalanche and fifteen non-avalanche slopes in the San Juan Mountains of Colorado, U.S.A. All slopes occurred in the subalpine zone. Six characteristics were used for analysis: type of slope, surface material, longitudinal profile, perched debris or debris tails, avalanche impact on opposite valley wall, and transverse profile. Both fan and roadbank avalanche slope types were found along with the non-avalanche slopes. Almost all slopes were turf covered rather than talus since the work was done below treeline. Twenty avalanche slopes had a distinctive concave longitudinal profile. Little debris of any kind was found since the slopes were in an area of insignificant amounts of detritus. Many of the larger and two of the smaller avalanche slopes showed evidence of impact upon the opposite slope. Eighteen of the avalanche slopes had convex transverse profiles.     

Snow-avalanche and debris-flow hazards in the fjords of north-western Iceland,mitigation and prevention

In the fjords of north-western Iceland, snow-avalanche and debris-flow hazards threaten 65% of the inhabitants. In this area, both historical and geomorphological evidences clearly demonstrate the recurrent danger from the steep slopes. Hazard vulnerability has increased during the last century, in connection with the population development of the Westfjords. Two snow-avalanche disasters during 1995 (in which 34 people were killed in two villages) prompted efforts to both mitigate and prevent future snow-avalanche and debris-flow activity. Research (qualitative and quantitative) on process characteristics describes prone terrain, runout distance, process behaviour along the slope, morphometric properties of the deposits and triggering factors. Acceptable risk, hazard and risk zoning are clearly defined by official regulations. Evacuation plans are determined from statistical characterisation of the risk and dynamic numerical modelling. To enhance the risk reduction, permanent and temporary measures aim to control the processes and to protect the population.     

MORPHOLOGY AND GROWTH PATTERNS OF THE USRI RIVER POINT BARS, BIHAR, INDIA

1 INTRODUCTIONThe exact mechanism of accumulation of sediments in point bars is not clearly known. Many scientistsinvestigated the problem. In the river Klaralven, Sundborg (1956) observed the development of sometransverse bars in the initial stage of the point bar formation. These transverse bars tend to becomelongitudinal as they extend close to the stream bed. Martvall and Nilsson (1972) investigated the problemof point bar formation experimentally in a laboratory flume. The flume st…