Google地图应用之广东省地区JOPENS地震速报系统

利用Google公司提供的电子地图服务,以B/S结构(即浏览器和服务器结构)作为系统设计架构,监听JOPENS实时系统发送的地震触发消息,访问JOPENS数据库,根据广东省地区的监测要求,制定检索、筛选策略,获取地震详细信息,显示在浏览器网页上.采用Google地图的JOPENS地震速报系统可以使地震信息发布的显示内容...     

太康4．7级地震前地震活动图像和趋势分析

对苏、鲁、皖、豫交界地区地震活动进行研究,指出该区2006年10月-2010年10月出现一个长轴约230km的3级地震空区。该空区及附近地区存在多项中期异常,即ML≥3地震活动具有频度高、能量强,中等地震震中空间分布相对集中及低b值等。讨论认为,苏、鲁、皖、豫交界地区存在多项中期异常,与2004年10月24日太康4．7级地震的强度不匹配,未来具有发生中强以上地震的危险。     

2010年玉树MS7.1地震前的中长期加速矩释放(AMR)问题

2010年4月14日青海玉树MS7.1地震前的加速矩释放(AMR)现象的研究,对理解这次地震的孕震过程、对于时间相依的地震危险性分析(或中长期地震预测)具有重要意义.鉴于以往AMR研究中的争论,本文不刻意选取AMR分析的时空尺度,而是在已知发震时刻和震中位置情况下,对T-R-MC三维空间中矩释放指数m值的分布进行分析,...     

强震前的“加速矩释放”（AMR）现象：对一个有争议的地震前兆的回溯性震例研究

近年来,国际上对于强震前的加速矩释放（AMR）现象是否可作为一种可靠的、带有普遍性的地震前兆现象争议较大.本文以2008年3月21日新疆于田M_S7.3地震为例,试图从前兆存在的客观性和与地震发生的物理相关性两方面考察本次地震前的AMR现象.用“破裂时间分析”方程中的幂指数m作为描述震前加速矩释放“程度”的参量,在时间-空间-地震序列截止震级组成的三维参数空间（T,R,M_c）内考察AMR现象存在的客观性.考虑了多种因素对m（T, R, M_c）分布图像可能的影响,其中,余震是否删除和M_c对计算影响不大,但M_L6.0以上“干扰”事件的影响则较大.结果表明,于田地震前的确存在AMR现象,但得到的m（T, R, M_c）分布图像较为复杂,可观测到两个明显的AMR集中分布区.此外,在以实际震中为圆心的多个圆形区域内,使用固定时间窗向实际发震时刻滑动逼近,可观测到m值逐渐减小,即加速特征逐渐明显的过程.对震前矩释放程度m值的时-空扫描结果显示,出现AMR现象的空间区域与震中位置似有较好的对应,但其时-空演化图像与滑动时-空窗的选取有关.这表明,本次M_S7.3地震前的确存在AMR现象,并与其孕震过程在物理上相关.但本文仅是一个震例的研究,无法给出具有统计显著性的结论,此外,用AMR来约束地震发生的时间看来是困难的.     

Precursory seismicity of the 1994 eruption of Popocatépetl Volcano,Central Mexico

Popocatépetl Volcano is located in the central Mexican Volcanic Belt, within a densely populated region inhabited by over 20 million people. The eruptive history of this volcano indicates that it is capable of producing a wide range of eruptions, including Plinian events. After nearly 70 years of quiescence, Popocatépetl reawakened in December 21, 1994. The eruptive activity has continued up until the date of this submission and has been characterized by a succession of lava dome growth-and-destruction episodes, similar to events that have apparently been typical for Popocatépetl since the fourteenth century. In this regime, the episodes of effusive and moderately explosive activity alternate with long periods of almost total quiescence. In this paper we analyze five years of volcano-tectonic seismicity preceding the initial eruption of the current episode. The evolution of the V-T seismicity shows four distinct stages, which we interpret in terms of the internal processes which precede an eruption after a long period of quiescence. The thermal effects of a magma intrusion at depth, the fracturing related to the slow development of magma-related fluid pathways, the concentration of stress causing a protracted acceleration of this process, and a final relaxation or redistribution of the stress shortly before the initial eruption are reflected in the rates of V-T seismic energy release. A hindsight analysis of this activity shows that the acceleration of the seismicity in the third stage asymptotically forecast the time of the eruption. The total seismic energy release needed to produce an eruption after a long period of quiescence is related to the volume of rock that must be fractured so imposing a characteristic threshold limit for polygenetic volcanoes, limit that was reached by Popocatépetl before the eruption.     

Comparison of source parameters estimated in the frequency and time domains for seismic events at the Rudna copper mine,Poland

Source parameters estimated in the frequency domain for 100 selected seismic events from the Rudna copper mine, with moment magnitude ranging from 1.4 to 3.6, were collected to study their scaling relations and to compare them with the parameters estimated in the time domain. The apparent stress and static stress drop, corrected for the limited bandwidth recording, increase slightly in a similar manner with increasing seismic moment. The ratio of apparent stress to static stress drop, a measure of radiation efficiency, is practically constant and its mean value is close to 0.1. For 37 seismic events, with moment magnitude between 1.9 and 3.4, source parameters were estimated in the time domain from relative source time functions, that displayed unilateral rupture propagation, and their rupture velocity could be estimated. It ranges from 0.23 to 0.80 of shear wave velocity and is almost independent of seismic moment. The fault length, estimated from the average source pulse width and rupture velocity, is clearly dependent on seismic moment and is smaller than the source radius estimated from the corner frequency on the average by about 25 percent. There is no correlation between the values of static stress drop estimated in the frequency and time domains, but the time domain stress drop is in general similar to that estimated in the frequency domain. The apparent stress increases with increasing rupture velocity, and the ratio of apparent stress to static stress drop seems also to depend on rupture velocity.     

爆炸应力波作用下缺陷介质裂纹扩展的动态分析

采用透射式焦散线测试系统,进行爆炸应力波作用下缺陷介质裂纹扩展试验,研究了含与炮孔共线的预制裂隙介质裂纹扩展速度、加速度、裂纹尖端动态应力强度因子和动态能量释放率的变化规律以及它们之间的变化关系。试验结果表明,在爆炸应力波作用下裂隙两端产生了两条翼裂纹A、B,翼裂纹A的长度较翼裂纹B长,两条翼裂纹向相反的方向扩展;在翼裂纹扩展过程中,存在着加速与减速的过程,扩展速度瞬间达到峰值,其后逐渐振荡下降;动态应力强度因子也呈现瞬间达最大值到逐渐减小连续振荡变化的趋势,动态应力强度因子 > ;翼裂纹尖端的动态能量释放率对裂纹扩展具有驱动作用。     

疏浚物中镉释放的影响条件

本文模拟研究了疏浚沉积物中Ｃd的释放行为和影响条件。结果表明介质的盐度、pＨ、氧化还原状态等环境条件和疏浚沉积物的污染程度、粒度大小、有机质含量等理化特征对Ｃd的 释放有明显的影响。Ｃd从疏浚物中释放,其释放速率较快,释放率在４０％～９６％之间。疏物的海上倾弃可能引起Ｃd的污染和对部分生态环境的危害。同时还讨论了Ｃd的释放所遵循的动力学规律。     

“7.20”华北特大暴雨过程中低涡发展演变机制研究

利用中国地面加密自动站观测资料、北京地区雷达探测资料、NCEP （1°×1°） FNL资料、ECMWF ERA Interim （0.125°×0.125°）逐日再分析资料等,对造成2016年7月19-20日华北极端暴雨中的低涡系统发展演变的结构特征和加强机制进行了研究。华北地区这次特大暴雨过程出现了3个阶段降水,其中与低涡系统强烈发展对应的第2阶段降水是本次华北暴雨过程的主要降水阶段。针对该低涡的分析表明：（1）850 hPa以西南低涡为中心的低压带中,在河南西北部新生低涡系统,并且其在向华北地区移动过程中显著加强,该低涡系统在空间结构上,从倾斜涡柱逐渐发展成近乎直立的、贯穿整个对流层的深厚低涡系统;（2）中低层低涡系统快速发展过程与高低空系统构成耦合作用有关：低层低涡系统显著加强之前,对流层上层（300-200 hPa）首先出现高空槽异常加深并向南发展,该高空槽发展的开始阶段与其本身冷暖平流造成的斜压发展过程对应;而后,随着高纬度平流层高位涡沿等熵面向南运动,造成华北地区对流层上层涡度增强,形成正位涡异常区;当这一正位涡异常区叠加在对流层中低层锋区上空时,造成对流层中低层气旋快速发展并向下伸展,诱发河南西北部的新生气旋;低涡系统的发展进一步强化了低空暖平流,促使低空气旋向东北方向发展"移动"（本质上是暖平流前端造成的气旋发展）,这一动力学过程反过来使高层的涡度增强;这一正反馈过程形成的耦合环流不仅造成了整个涡度柱强度增强,而且垂直结构上逐渐由倾斜涡柱演变为近乎于直立的涡柱;（3）随着低涡系统增强,极大地加强了垂直上升运动并触发了对流,形成大范围的强降水,大量的凝结潜热释放,造成了低层低涡系统在强降水开始阶段的快速发展和增强;20日00时（世界时）以后,虽然对流活动显著减弱,但低涡系统的加深维持了大范围强降水过程的持续。强降水与低涡发展的正反馈过程是这次华北暴雨得以长时间维持的重要机制之一,这一过程形成的持续性潜热释放也是对流层中上层低涡系统热力结构发生改变的重要原因。     

Roles of Mesoscale Terrain and Latent Heat Release in Typhoon Precipitation： A Numerical Case Study

The mesoscale orographic effects on typhoon Aere＇s precipitation are simulated using an Advanced Regional Eta-coordinate Model （AREM） version 3.0. In particular, the effects of the latent heat release are studied by two comparable experiments： with and without condensational heating. The results show that the typhoon rainfall is tripled by the southeastern China mesoscale terrain, and the condensational heating is responsible for at least half of the increase. One role of the latent heat release is to warm the atmosphere, leading to a depression of the surface pressure, which then causes a larger pressure difference in the zonal direction. This pressure gradient guides the water vapour to flow into the foothills, which in turn amplifies the water vapour flux divergence amplified, causing the typhoon rainfall to increase eventually. The other role of the latent heat release is to make the convection more organized, resulting in a relatively smaller rain area and stronger precipitation.