合肥地区地闪特征

根据观测资料 ,分析了利用闪电辐射场信号大容量采集系统观测到的合肥地区地闪回击特征。结果表明 ,每次地闪回击数频率分布并不表现为简单的指数衰减特征 ,回击数在 5次以下的各回击数出现频率几乎相当 ,单次回击地闪的比重只有约 1 5 %。平均地闪回击数为 4 .2次 ,观测到的最大回击数为 1 6次。地闪回击归一化电场强度近似服从对数正态分布。 1 69例首次回击平均电场强度为 9.3V·m- 1 (归一化到 1 0 0km ,下同 ) ,485例继后回击的平均电场强度只有 4 .5V·m- 1 。 480例继后回击与首次回击场强之比平均为 0 .6 ,有 1 8%地闪过程至少有一次比首次回击强的继后回击。相邻两次回击间隔时间呈现对数正态分布特征。观测到的最短回击间隔为 1 .6ms ,约 30 %的回击间隔 >1 0 0ms,在40～ 1 0 0ms之间的回击间隔比重约为 50 %。回击间隔时间与间隔前后回击相对强弱之间存在系统性的变化趋势 ,当两次回击间隔在 40ms以下时总是以‘前强后弱’的回击组合占主导地位 ,相反 ,当回击间隔时间增加到 >1 0 0ms时 ,约 55 %的回击间隔表现为‘前弱后强’的回击组合。     

“菲特”(1323)台风降水的极端性分析

基于1981—2013年间的热带气旋降水资料,使用百分比法研究了台风"菲特"所带来降水的极端特性,并进行了降水重现期特征分析。结果表明:台风"菲特"期间的日降水量、小时雨强、过程降水量超过"单站热带气旋极端降水阈值"和"中国热带气旋极端降水阈值"的站点几乎覆盖了整个上海以及浙江北部地区,并且日降水量和过程降水量达百年一遇标准的也占相当大的比例,甚至有的站点创历史极值,此次过程在这些地区是很罕见的。相比较而言,"菲特"影响期间,极端日降水和极端过程降水的分布范围以及极端性都大于小时雨强,极端过程降水较极端日降水分布范围小,但极端性更强。     

我国住宅区日照标准下墙面晴天太阳辐射分析

为研究我国不同地区住宅通过垂直墙面上的窗口实际接受到的太阳辐射量空间分布特征,以卡斯特洛夫公式为基础,建立了各朝向墙面晴天太阳总辐射和直接辐射小时总量的计算方案。使用水汽压和海拔高度拟合了公式中的参数,计算了我国各地满足国家标准对住宅间距要求下的水平面和垂直墙面辐射量,并绘制了分布图。研究发现:大寒日各朝向墙面晴天最大2 h辐射量空间分布受纬度和大气透明度共同影响,青藏高原为全国高值中心,川黔地区为低值中心。在我国东部地区,与水平面辐射量随纬度增加而降低的规律相反,同样是辐射量最大的2 h日照时间,纬度越高的地区南墙面接受的太阳辐射量就越大。与南墙相比,东、西墙面接收的最大2 h辐射量明显偏小,不能发挥阳光对健康和卫生的作用。上述结果表明,从大寒日建筑底层南墙面接收的最大2 h辐射量上看,适当放宽北方地区日照间距标准具有一定可行性。     

磁县—大名断裂带西段晚更新世以来活动性研究

1830年河北磁县M7■地震发生于磁县—大名断裂带西段,该断裂地震破裂和活动性的研究受到地震研究者关注。前人研究着眼于1830年磁县大地震的地表破裂,本文的研究重点是磁县—大名断裂带西段晚更新世以来的断层活动性。应用卫片、航片解译和野外地震地质调查等方法开展研究,重要地点进行探槽开挖或野外地质剖面剥落以及采样测年,确定了断层各段落破裂事件的发生年代。该断裂西段分为3个断层段落:F₂为磁县—峰峰段落, F₃为东田井村—陶泉乡段落, F₄为韩家沟村—甘泉村段落。F₂断层段大部分隐伏,为早中更新世断层。F₃断层段东端在东田井村南断错距今22 ka地层,为晚更新世活动断层; F₃断层段在鼓山南山村一带为全新世断层,从张家楼村到陶泉乡为推测全新世活动断层。F₄断层段为全新世断层。F₄断层段全部位于基岩山区,可见多处基岩断面、地震沟槽及断层眉脊等断层破裂;一些破裂面发育地衣——丽石黄衣[Xanthoria elegans(L...     

土层锚杆高压注浆工艺的研究

通过对土层锚杆施工中的高压注浆工艺进行研究，得出了一套有效的工艺方法。     

Evaluation of the use of paleotsunami deposits to reconstruct inundation distance and runup heights associated with prehistoric inundation events,Crescent City,southern Cascadia margin

Historic‐ and prehistoric‐tsunami sand deposits are used to independently establish runup records for tsunami hazard mitigation and modeled runup verification in Crescent City, California, located in the southern Cascadia Subduction Zone. Inundation from historic (1964) farfield tsunami (~5–6 m runup height) left sand sheet deposits (100–200 m width) in wetlands located behind a low beach ridge [3–4 m elevation of the National Geodetic Vertical Datum of 1988 (NAVD88)]. The most landward flooding lines (4·5–5 m elevation) in high‐gradient alluvial wetlands exceed the 1964 sand sheet records of inundation by 1–2 m in elevation. The most landward flooding in low‐gradient alluvial wetlands exceed the corresponding sand sheet record of inundation distance by 1000 m. Nevertheless, the sand sheet record is an important proxy for high‐velocity inundation. Sand sheet deposition from the 1964 historic tsunami closely corresponds to the landward extent of large debris transport and structural damage in the Crescent City waterfront. The sand sheet deposits provide a proxy for maximum hazard or ‘kill zone’ in the study area. Six paleotsunami sand sheets (0·3–3 ka) are recorded in the back‐ridge marshes in Crescent City, yielding a ~450 year mean recurrence interval for nearfield Cascadia tsunami. Two paleotsunami sand deposit records, likely correlated to Cascadia ruptures between 1·0 and 1·5 ka, are traced to 1·2 km distance and 9–10 m elevation, as adjusted for paleo‐sea level. The paleotsunami sand deposits demonstrate at least twice the runup height, and four times the inundation distance of the farfield 1964 tsunami sand sheet in the same marsh system. The preserved paleotsunami deposits in Crescent City are compared to the most landward flooding, as modeled by other investigators from a predicted Cascadia (~ Mw 9) rupture. The short geologic record (~1·5 ka) yields slightly lower runup records than those predicted for the modeled Mw 9 rupture scenario in the same marsh, but it generally verifies predicted maximum tsunami runup for use in the planning of emergency response and rapid evacuation. Copyright © 2011 John Wiley & Sons, Ltd.     

Recurrence pattern of Holocene earthquakes along the Dead Sea transform revealed by varve-counting and radiocarbon dating of lacustrine sediments

A high-resolution Holocene seismic history of the Dead Sea Transform (DST) is established from laminated sedimentary cores recovered at the shores of the Dead Sea. Radiocarbon dating and annual laminae counting yield excellent agreement between disturbed sedimentary structures (identified as seismites) and the historical earthquake record: All recent and historical strong events of the area were identified, including the major earthquakes of A.D. 1927, 1837, 1212, 1033, 749, and 31 B.C. The total of 53 seismites recognized along the entire Holocene profile indicate varying recurrence intervals of seismic activity between a few and 1000 years, with a conspicuous minimum rate at 2100-31 B.C. and a noticeable maximum during the past six to eight centuries. Most of the epicenters of the correlated earthquakes are situated very close to the Dead Sea (within 150 km) or up to 400 km north of it along the DST. Between 1000 B.C. and A.D. 1063, and from A.D. 1600 to recent time the epicenters are all located on the northern segment of the DST, whereas prior to 1000 B.C. and between A.D. 1000 and 1600 they appear to scatter along several segments of the DST. We establish how the local intensity exerts a control on the formation of seismites. At historically estimated intensities greater than VII, all well documented earthquakes are correlated, whereas at intensities smaller than VI none are matching.The periods with enhanced earthquake rate along the DST correlate with those along the North Anatolian Fault as opposed to the intervening East Anatolian Fault. This may indicate some elastic coupling on plate-boundary scale that may also underlie escape and extrusion tectonics, typical of continental collision.     

龙陵-瑞丽断裂北段晚第四纪活动性特征及强震复发间隔1

野外地质地貌调查表明,龙陵-瑞丽断裂（南支）北段是以左旋走滑为主兼具一定正断分量的区域性活动断裂。断裂晚更新世以来的平均水平滑动速率为2.2mm/a,平均垂直滑动速率为0. 6mm/a;全新世以来的平均水平滑动速率为1.8—3.0mm/a,平均垂直滑动速率为0.5mm/a。断裂在晚更新世以来的滑动速率在不同的时间尺度上变化不大,反映出该断裂晚更新世以来的活动强度比较稳定。利用Poisson模型、Lognormal模型、BPT模型三种概率模型计算获得未来50a强震发震概率分别是：6.32%、0.08%、0.05%;三种模型分别取权重0.28、0.36、0.36,获得龙陵-瑞丽断裂北段未来50a特征地震发震概率为1.82%。     

台湾及其邻近地区ML6.5以上地震活动的一些特征

依据地震活动间隔时间对数-频次符合指数关系的特征,分析了1971年至2000年台湾及其邻近地区ML6.5以上地震间隔时间对数与拟合直线斜率之间的的统计关系,依据这一关系对各震例进行了时序扫描,结果表明,可依据预测时间对数与统计时间对数之差的变化特征,在部分震例发生前对其发生的时间进行震前短期预测.     

Maximum-likelihood estimation of unsaturated hydraulic parameters

Maximum-likelihood estimators properly represent measurement error, thus provide a statistically sound basis for evaluating the adequacy of a model fit and for finding the multivariate parameter confidence region. We demonstrate the advantages of using maximum-likelihood estimators rather than simple least-squares estimators for the problem of finding unsaturated hydraulic parameters. Inversion of outflow data given independent retention data can be treated by an extension to a Bayesian estimator. As an example, we apply the methodology to retention and transient unsaturated outflow observations, both obtained on the same medium sand sample. We found the van Genuchten expression to be adequate for the retention data, as the best fit was within measurement error. The Cramer–Rao confidence bound described the true parameter uncertainty approximately. The Mualem–van Genuchten expression was, however, inadequate for our outflow observations, suggesting that the parameters (, n) may not always be equivalent in describing both retention and unsaturated conductivity.