内蒙古地区地震活动度S值特征分析     

高立新 《东北地震研究》2004,20(2):15-20

采用定量描述地震活动强弱程度的地震活动度方法，研究了内蒙古地区1970年以来中强地震的分布特征和活动规律，发现内蒙古地区S值存在5年周期的起伏活动规律。在分区研究区的基础上，内蒙古地区从西到东，地震活动度S值呈现有规律的强一弱交替特征。  相似文献   

利用前兆事件对云南地区地震进行中短期预测研究   总被引：1，自引：0，他引：1       下载免费PDF全文

秦嘉政  钱晓东 《地震学报》2004,26(2):140-150

对某些类型的主震事件, 进行中短期预测也许是可能的. 利用Varnes, Bufe和Varnes提出的破裂时间法模拟前兆地震能量加速释放模型,通过实际观测资料与理论公式的拟合, 可以建立主地震事件的中短期预测技术, 用以确定表示主震的地点、时间和震级大小. 本文使用的是云南区域台网的地震目录资料，覆盖的时间段为1965~2002年. 统计分析表明，在此37年时间内，等于或大于2.5级地震资料是相当完整的. 本文对云南地区的30次主震事件进行了模拟，其中25次主震事件由前兆序列模拟得到的预测时间和震级与实际值相当接近，主震震级预测精度约0.57个震级单位，假定已知前兆序列中最后一次事件，则预测主震发生时间误差约0.64年.对另外的5次主震事件，由于没有足够的前兆事件来充分确定前兆能量加速曲线或是存在对能量加速释放曲线的干扰事件，而不能进行破裂时间法模拟.本文的研究结果还表明，由于云南是破坏性地震和中小地震活跃的地区，因此，主地震与前兆事件最佳搜索半径不存在明显的线性关系.主震矩与系数k，m之间存在强烈的相关性，利用主震地震矩与系数的关系和限制指数m的取值范围，可进一步缩小预测时间和预测震级的最佳拟合区范围，提高了模拟主震事件的预测精度. 本文采用破裂时间法对30次主震事件进行拟合，80％以上获得了较好的结果. 显示出该方法在预测已知主震事件序列的能力方面大有希望，因此，利用前兆事件对未来主震事件进行中短期预测的前景是令人鼓舞的.   相似文献   

江苏及南黄海地区历史地震类型分布特征          下载免费PDF全文

田建明  徐徐  谢华章  杨云  丁政 《地震学报》2004,26(4):432-439

通过对江苏地区及南黄海海域历史地震资料特点分析，将研究区历史地震类型分为相对安全类和相对危险类，并对地震类型的统计结果、地理分布特征及构造进行探讨. 结果表明:① 江苏及南黄海地区绝大多数中强以上历史地震类型为相对安全类，仅有13.8%的中强以上历史地震为相对危险类；② 江苏陆地、长江口以东海域和南黄海北部坳陷地区以相对安全类地震为主，苏中沿海南黄海海域地震类型分布较为复杂，相对安全类和相对危险类地震类型比例基本相当；③ 研究区历史地震类型统计结果和空间分布特征与现代地震序列类型实况非常吻合，反映本区地震活动具有继承性的特点.研究结果可以作为江苏省地震应急工作中震后早期趋势判定的参考依据.   相似文献   

遥感图象自动识别城市震害房屋-以2001年印度库奇地震和1976年唐山地震为例   总被引：6，自引：0，他引：6       下载免费PDF全文

柳稼航  单新建  尹京苑 《地震学报》2004,26(6):623-633

近断层地震动对地表结构物造成严重的破坏，它具有明显的方向性和脉冲型特征. 在速度时程中含有大幅值、长周期的脉冲波，对结构响应影响很大. 为简化计算和分析的需要，在既有的等效速度脉冲模型的基础上，建议了较为合理等效速度脉冲模型. 在充分收集脉冲型近断层地震记录的基础上，对等效速度脉冲模型的脉冲周期、脉冲强度及卓越脉冲数等参数进行了研究，并与以往研究者的结果进行比较，以利于近断层区结构的抗震设计.   相似文献   

Parameters of Land-Surface Processes for Gobi in North-West China   总被引：1，自引：0，他引：1  

Zhang Qiang  Huang Ronghui 《Boundary-Layer Meteorology》2004,110(3):471-478

Using data from the intensive observation period (May–June 2000) of the NWC-ALIEX (The Field Experiment on Interaction between Land and Atmosphere in Arid Region of North-west China), the characteristics and mechanisms of some key land-surface process over Gobi in a typical arid region of north-west China are analyzed and several parameters of land-surface processes are calculated. The weighted mean of the surface albedo over a typical arid region of the Dunhuang Gobi is calculated using the relative reflection as a weighting factor, and its value is 0.255 ± 0.021. After removing the influence of precipitation, the mean soil heat capacity over a typical arid region of the Dunhuang Gobi is 1.12 × 10⁶ J m^-3 K^-1,which is smaller than that observed in the Heihe (China) River basin Field Experiment (HEIFE). The mean soil heat diffusivity and conductivity are about half of those observed in HEIFE.  相似文献   

多年冻土区路桥过渡段的一种新结构     

刘建坤  鲍维猛  黎明  葛建军 《冰川冻土》2004,26(Z1):210-214

The design of roadbed-abutment transition part is always a challenging problem in transportation engineering, especially in permafrost distribution zone. A new type of roadbed-abutment transition part on permafrost was presented, and long-term observation was conducted for the deformation and the thermal regime of a roadbed-abutment transition part in the constructing Qinghai-Tibet Railway. In this paper, a new structure was presented and the observed settlements both in the subgrade and the base and its dependency with the thermal regime (permafrost table) were analyzed. In conclusion the roadbed-a-butment transition method for permafrost distribution zone was evaluated.  相似文献   

Tortoises and hares: dissolution,erosion and isostasy in landscape evolution     

Michael J. Simms 《地球表面变化过程与地形》2004,29(4):477-494

Denudation mechanisms differ fundamentally between limestone and silicate rock types, which are subject to very different rate thresholds and enhancers/inhibitors. Silicates are removed largely by erosion, the mechanical entrainment and transport of particles. This is a relatively high energy, and highly episodic, process which occurs only when a minimum threshold ?ow velocity is exceeded; it is inhibited by vegetation cover and favoured by strongly seasonal runoff. Limestone is removed largely by chemical dissolution at a rate directly proportional to runoff. Dissolution is a relatively low energy process that can occur at any ?ow velocity or in static water; in general it is enhanced by vegetation cover and non‐seasonality of runoff. These contrasting factors in the denudation of silicates versus limestone can produce strikingly uneven rates of surface lowering across a landscape, sometimes akin to the well known ‘tortoise and hare race’, where the slow and steady denudation of limestones may in the long term exceed the sometimes rapid, but often localized and episodic, erosion of silicates. Prolonged exposure of limestone to a humid temperate climate in a tectonically stable environment produces low‐relief corrosion plains in which limestone uplands are anomalous and, in most instances, due to recent unroo?ng from beneath a siliciclastic cover. In a highly seasonal or semi‐arid climate almost the exact inverse may develop, with ‘?ashy’ runoff and sparse vegetation favouring erosion rather than dissolution. Even under a constant humid climate progressive unroo?ng of a thick limestone unit within folded siliciclastics may lead to a topographic inversion over time, with the limestone outcrop always forming a topographic low ?anked by siliciclastic uplands. Valleys will be initiated on anticlinal crests, where the limestone is ?rst unroofed, but progressive lowering of the limestone causes these valleys to migrate to their ?nal position in the synclinal troughs. In humid climates isostatic compensation in response to slow, but continuous, denudation of extensive limestone outcrops may be a signi?cant factor in the development of relief on adjacent, more slowly eroding, silicate outcrops. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Study on Ground Motion Attenuation Relation in Shanghai and Its Adjacent Region     

Shi Shuzhong 《中国地震研究》2004,18(2):105-113

Based on intensity data in Shanghai and its adjacent region, the intensity attenuation relation is determined. Selecting the western United States as a reference area where there are rich strong ground motion records and intensity data, and by determining ground motion attenuation relation in an area lacking in strong ground motion data, we obtain the ground motion attenuation relation in Shanghai and its adjacent region.  相似文献   

Features of the M7.9 Earthquake in the Russia- Mongolia- China Boundary Region     

Rou Jie 《中国地震研究》2004,18(4):357-364

At 19:33 p. m on September 27, 2003, an earthquake with M7.9 occurred in the RussiaMongolia-China boundary Region. It was strongly felt in the Altay region of Xinjiang. The losses caused by the earthquake was 76 million yuan (RMB). Some information about the earthquake was outlined, including basic parameters, focal mechanism, evaluation of earthquake disaster losses and so on. The satellite remote sensing information worked initial analysis for deformation of ground and failure phenomenon.  相似文献   

临汾"8.26"区域性大暴雨过程分析   总被引：2，自引：0，他引：2       下载免费PDF全文

张临平  王智娟  史海平  戴有学  孙悦 《山西气象》2004,(4):5-6,10

利用micaps业务平台常规资料、数值预报产品、卫星云图，对临汾市2003年8月26日区域性暴雨和大暴雨的环流背景、影响系统、热带低压登陆副热带高压东退以及物理量条件进行了诊断分析，探讨了副热带高压进退及台风登陆位置在这次大暴雨过程中起到了非常重要的作用。分析结果在暴雨预报业务及暴雨研究中有一定的指示意义。  相似文献