用远场资料反演西藏玛尼地震的高阶地震矩张量   总被引：9，自引：2，他引：7       下载免费PDF全文

刘瑞丰  陈运泰  Frank Krueger  成瑾  杨辉  韩炜  牟磊育 《地震学报》2000,22(3):225-232

采用扩展震源模型测定出更多的震源参数 .我们把震源用高阶地震矩张量表示 .为了减少在高阶地震矩张量表达式中出现的大量项 ,采用了 Haskell断层模型 .利用 GSN台网 32个台站的宽频带体波资料 ,反演了西藏玛尼地震的震源参数 .通过实际计算表明 ,该震源是一个走滑断层 ,破裂方向 75°,断层面为=77°、δ=88°,λ=0°,辅助面为=347°、δ=90°、λ=1 78°,破裂持续时间为 1 9s,断层尺度为 47km× 2 8km.这些结果将为地球动力学研究提供新的定量资料 ,对于震源层析成像研究等有实际意义 .  相似文献   

Runoff and road erosion at the plot and road segment scales,St John,US Virgin Islands     

Lee H. MacDonald  Robert W. Sampson  Donald M. Anderson 《地球表面变化过程与地形》2001,26(3):251-272

Previous studies have identified unpaved roads as the primary source of erosion on St John in the US Virgin Islands, but these studies estimated road erosion rates only as annual averages based primarily on road rill measurements. The goal of this project was to quantify the effect of unpaved roads on runoff and sediment production on St John, and to better understand the key controlling factors. To this end runoff and sediment yields were measured from July 1996 to March 1997 from three plots on naturally vegetated hillslopes, four plots on unpaved road surfaces and two cutslope plots. Sediment yields were also measured from seven road segments with contributing areas ranging from 90 to 700 m². With respect to the vegetated plots, only the two largest storm events generated runoff and there was no measurable sediment yield. Runoff from the road surface plots generally occurred when storm precipitation exceeded 6 mm. Sediment yields from the four road surface plots ranged from 0·9 to 15 kg m⁻² a⁻¹, and sediment concentrations were typically 20–80 kg m⁻³. Differences in runoff between the two cutslope plots were consistent with the difference in upslope contributing area. A sprinkler experiment confirmed that cross‐slope roads intercept shallow subsurface stormflow and convert this into surface runoff. At the road segment scale the estimated sediment yields were 0·1 to 7·4 kg m⁻² a⁻¹. Road surface runoff was best predicted by storm precipitation, while sediment yields for at least three of the four road surface plots were significantly correlated with storm rainfall, storm intensity and storm runoff. Sediment yields at the road segment scale were best predicted by road surface area, and sediment yields per unit area were most strongly correlated with road segment slope. The one road segment subjected to heavy traffic and more frequent regrading produced more than twice as much sediment per unit area than comparable segments with no truck traffic. Particle‐size analyses indicate a preferential erosion of fine particles from the road surface and a rapid surface coarsening of new roads. Published in 2001 by John Wiley & Sons, Ltd.  相似文献   

Debris-flow volumes in northeastern Italy: Relationship with drainage area and size probability     

Lorenzo Marchi  Maria Teresa Brunetti  Marco Cavalli  Stefano Crema 《地球表面变化过程与地形》2019,44(4):933-943

A dataset of 809 debris flows that occurred in 537 basins in mountainous areas of northeastern Italy between the mid-19th century and 2015 is collected and analyzed. A remarkable increase in the number of events is observed in the last four decades and is mainly ascribed to more systematic data collection. The correlation between debris-flow volume and drainage basin area is obtained assuming a power-law relationship. The exponent of the power-law curve at the 50th percentile (0.67 ± 0.02) indicates negative allometry, which means that basin area grows out of proportion to debris-flow volume. In contrast, the exponents at the 98th and 99th percentiles are close to one, implying that debris-flow volumes grow linearly with basin areas. The isometric relationship between the largest debris flows and the corresponding basin areas is due to the enhanced debris supply provided by the activation of widespread sediment sources, the extent of which is proportional to the basin size. The probability density function of debris-flow volume for a subset of the collected dataset is calculated using the kernel density estimation function, which permits estimating the probability of the occurrence of debris flows that exceed a given threshold volume. The comparison with debris flows in other hydroclimatic regions shows that, although debris-flow volumes in northeastern Italy may attain high values, they are often exceeded by debris flows that occur in seismically active regions and/or are triggered by more intense rainstorms. © 2018 John Wiley & Sons, Ltd.  相似文献   

震级国家新标准在内蒙古测震台网速报中的应用     

郝美仙  张建中  徐岩  张珂 《地震地磁观测与研究》2019,40(6):40-46

选取内蒙古测震台网2016年1月—2018年9月速报的地震,按照新的国家标准《地震震级的规定》(GB17740—2017)和现行地震速报规定分别重新测定震级,并测定矩震级。结果表明:新国标测定的地震数可较好地满足G—R线性关系,且所测震级更接近矩震级。震级新的国家标准应用后,速报的震级下限降低,地震数明显增加,可有效满足社会发展对有感地震监测服务的需求,并更加科学地为地震预报研究提供基础数据资料。  相似文献   

张掖M_S 5.0地震前山丹地震台地电阻率异常分析     

王志栋  雷正超  寇俊阳  张成军  吴敏  安张辉 《地震地磁观测与研究》2020,41(4):83-89

通过分析山丹地震台地电阻率资料发现,在2019年9月16日张掖M_S 5.0地震前地电阻率出现了明显的异常变化,即2016年11月开始EW测道观测数据出现年变畸变异常,年变幅度几近消失,该异常持续至2018年年底。采用傅里叶滑动去年变分析发现,同段年变消失,去年变后数值出现超阈值异常;采用矩平处理方法分析发现,2016年11月至2018年10月观测值小于矩平拟合值,出现低值异常。研究表明,该异常可能与2019年9月16日张掖M_S 5.0地震有关。  相似文献   

Analytic scaling laws in planetary dynamo models     

S. V. Starchenko 《地球物理与天体物理流体动力学》2019,113(1-2):71-79

ABSTRACT

Numerical models of planetary MHD dynamos have led to many advances in the last twenty years. However, the accessible parameter space of these models is somewhat limited due to computational constraints. A number of numerically based scaling laws have been proposed, but it has been difficult to reliably confirm them from the simulation data alone. Since these scaling laws have to be used to extend the numerical models into the planetary parameter regime, getting correct scalings is an important issue. Here some possible balances between the relevant terms in the dynamo equations are considered, and a number of different known and new scaling laws are proposed and justified from analytical point of view. Some of these laws are compatible with the widely known Christensen and Aubert (Geophys. J. Int. 2006, 166) scaling for the magnetic field strength. Plausible estimates of the typical values of the important quantities in the Earth's core and other Terrestrial planets are made, and the extent to which the various scaling laws are consistent with these estimates is discussed.  相似文献   

Testing of observation operators designed to estimate profile soil moisture from surface measurements   总被引：1，自引：0，他引：1  

Xiaodong Gao  Xining Zhao  Luca Brocca  Daili Pan  Pute Wu 《水文研究》2019,33(4):575-584

The accurate estimation of profile soil moisture is usually difficult due to the associated costs, strong spatiotemporal variability, and nonlinear relationship between surface and profile moisture. Here, we used data sets from the Soil and Climate Analysis Network to test how reliably observation operators developed based on the cumulative distribution function matching method can predict profile soil moisture from surface measurements. We first analysed how temporal resolution (hourly, daily, and weekly) and data length (half year, 1 year, 2 years, and 4 years) affected the performance of observation operators. The results showed that temporal resolution had a negligible influence on the performance of observation operators. However, a leave‐one‐year‐out cross‐validation showed that data length affected the performance of observation operators; a 2‐year interval was identified as the most suitable duration due to its low uncertainty in prediction accuracy. The robustness of the observation operators was then tested in three primary climates (humid continental, humid subtropical, and semiarid) of the continental United States, with the exponential filter employed as an independent method. The results indicated that observation operators reliably predicted profile soil moisture for most of the tested stations and performed almost equally well as the exponential filter method. The presented results verified the feasibility of using the cumulative distribution function matching method to predict profile soil moisture from surface measurements.  相似文献   

北京城区地下热水结垢趋势的判断和分析     

于湲  周训  方斌 《城市地质》2007,2(2):14-18

结垢天地下热水供暖系统运行中普遍存在的现象,对地下热水的腐蚀结垢趋势的计算和判断对于整个工艺运行的稳定性至关重要。本文以北京城区地热田10个代表性地热井为例,采用指数(雷兹诺指数和拉申中指数)判断法以及WATCH程序对地下热水的结垢趋势进行计算和判定,结果表明,城区地热田的大部分地下热水有结垢的可能性,导致结垢的主要矿物是方解石和温石棉。  相似文献   

2000年姚安MS6.5地震3.0≤ML ＜5.0余震的地震矩张量反演   总被引：1，自引：1，他引：0  

毛燕  王彬  周光全 《地震研究》2006,29(2):131-136

建立合于云南地区的速度结构模型,对云南数字地震台网记录的2000年姚安Ms6．5地震3．0≤ML〈5．0余震的垂直分量进行频率域内的地震矩张量反演。结果表明：矩张量分解得到纯膨胀（各向同性）分量P、纯剪切（双力偶）分量M0和补偿线性矢量偶极C三部分,其中纯剪切（双力偶）分量帆占主要部分,表明地震的震源破裂过程以剪切破裂为主。从余震震源机制解可知,NW-NWW方位的节面占主导,结合余震分布尺度可以判断发震断裂是北西向的断裂。  相似文献   

磁变仪标度值自动测定电路的改进     

田树德  翟彦忠  马光  李卫国  高登平  王树兴  吴俊花 《地震地磁观测与研究》2006,27(4):118-121

介绍了改进后的磁变仪标度值自动测定电路的主要特性、电路工作原理和使用注意事项,提供了电路原理图。  相似文献