北天山地区2011 年以来两次6 级地震前的地震学中短期异常特征

通过分析北天山地区历史强震、构造活动背景、区域应变能积累特征以及2011 年11月1 日尼勒克、巩留交界6. 0 级和2012 年6 月30 日新源、和静交界6. 6 级地震前区域地震活动异常特征等,探讨了这两次6 级地震前的地震学中短期异常特征。结果表明,2011 年6 月以来北天山地区中强以上地震处于加速活动状态,进入应变能释放阶段;尼勒克、巩留交界6. 0 级和新源、和静交界6. 6 级地震震前先呈6 级地震平静而后被打破、中强地震成组活动和空间迁移、条带和空区等较明显的中期异常;震前还出现了较为相似的4 级以上地震围空和5 级逼近地震,且逼近地震与主震发生时间间隔均为14 天,显示了较清晰的异常图像和较明显的中短期震兆特征。     

中俄交界4.8级地震综合震源机制解及构造应力场

利用P波初动求解中俄交界4.8级地震的综合震源机制,通过震源机制反演震源区附近的应力场,结果表明:此次地震是略带走滑分量的正断层.主压应力场的方向是北北东方向,沿此断裂带展布.     

黑龙江省测震台网监测能力评估

通过对黑龙江邻省相关台站测震数据共享和近几年台网建设规划的实施发现,该省测震台网监测能力得到进一步提高.     

High-resolution seismic tomography of the upper crust in the source region of the April 20, 2013 Lushan earthquake and its seismotectonic implications

Both P- and S-wave arrivals were collected for imaging upper crustal structures in the source region of the April 20, 2013 Lushan earthquake. High-resolution, three-dimensional P and S velocity models were constructed by travel-time tomography. Moreover, more than 3700 aftershocks of the Lushan earthquake were relocated via a grid search method. The P- and S-wave velocity images of the upper crust show largely similar characters, with high and low velocity anomalies, which mark the presence of significant lateral and vertical heterogeneity at the source region of the Lushan earthquake. The characteristics of the velocity anomalies also reflect the associated surface geological tectonics in this region. The distributions of high velocity anomalies of both P- and S-waves to 18 km depth are consistent with the distributions of relocated aftershocks, suggesting that most of the ruptures were localized inside the high velocity region. In contrast, low P and S velocities were found in the surrounding regions without aftershocks, especially in the region to the northeast of the Lushan earthquake. For the relocated aftershocks of the Lushan earthquake from this study, we found that most aftershocks were concentrated in a zone of about 40 km long and 20 km wide, and were located in the hanging wall of Dayi–Mingshan fault. The focal depths of aftershocks increase from the southeast to the northwest region in the direction perpendicular to the fault strike, suggesting that the fault ruptured at an approximate dip angle of 45°. The main depths of the aftershocks in the northwest of the main shock are significantly shallower than expected, revealing the different seismogenic conditions in the source region.     

The Chemical Composition of the Field Zero-Age Star HD77407

High-resolution optical spectra of the zero age star HD77407 are analysed and its Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Co, Ni and Ba contents are determined using spectral synthesis method. The temperature of the star is determined by fitting the H α line wings. The parameters derived for this star are Teff=5900K, log g=4.47 and [Fe/H] = 0.07. It is found that the derived iron content is slightly higher than what is given in the published literature. This star shows a relative overabundances of Ca and Ba, and underabundances of Na, V and Ni with respect to the solar mix. Activity of the star is indicated by the filled in Hα and Ca II triplet line cores. It has been confirmed that our spectroscopic approach yields fairly reliable and consistent results for active stars.     

黑龙江省漠河推覆构造特征及其与金成矿的关系

漠河推覆构造发育于上黑龙江盆地的北西部,是漠河地区的主要构造样式,形成于晚侏罗世-早白垩世之间。推覆方向总体由NW向SE,具有前展式的扩展方式。推覆构造在空间上由一系列近平行排列的逆冲断层组成,剖面上表现为犁式逆冲断裂所构成的单冲式叠瓦状构造,按其变形变质特征可划分为6条构造分带。漠河推覆构造对上黑龙江盆地金矿床的时、空分布具有明显的控制作用,其中砂宝斯金矿床受控于推覆构造脆性断裂破碎带,矿体产于构造界面之上的层间破碎带和SN向陡倾断裂破碎带中;老沟、砂宝斯林场金矿床受控于推覆构造韧性剪切带,矿体产于NE向脆性构造破碎带中。金矿床(点)主成矿期为早白垩世。综合研究漠河推覆构造的控矿特点,对该区实现新的找矿突破具有重要意义。     

A strategy for merging objective estimates of global daily precipitation from gauge observations,satellite estimates,and numerical predictions

This paper describes a strategy for merging daily precipitation information from gauge observations, satellite estimates(SEs), and numerical predictions at the global scale. The strategy is designed to remove systemic bias and random error from each individual daily precipitation source to produce a better gridded global daily precipitation product through three steps.First, a cumulative distribution function matching procedure is performed to remove systemic bias over gauge-located land areas. Then, the overall biases in SEs and model predictions(MPs) over ocean areas are corrected using a rescaled strategy based on monthly precipitation. Third, an optimal interpolation(OI)–based merging scheme(referred as the HL-OI scheme)is used to combine unbiased gauge observations, SEs, and MPs to reduce random error from each source and to produce a gauge—satellite–model merged daily precipitation analysis, called BMEP-d(Beijing Climate Center Merged Estimation of Precipitation with daily resolution), with complete global coverage. The BMEP-d data from a four-year period(2011–14) demonstrate the ability of the merging strategy to provide global daily precipitation of substantially improved quality.Benefiting from the advantages of the HL-OI scheme for quantitative error estimates, the better source data can obtain more weights during the merging processes. The BMEP-d data exhibit higher consistency with satellite and gauge source data at middle and low latitudes, and with model source data at high latitudes. Overall, independent validations against GPCP-1DD(GPCP one-degree daily) show that the consistencies between BMEP-d and GPCP-1DD are higher than those of each source dataset in terms of spatial pattern, temporal variability, probability distribution, and statistical precipitation events.     

Estimating the Numbers and the Areas of Collapsed Buildings by Combining VHR Images,Statistics and Survey Data: a Case Study of the Lushan Earthquake in China

Accurately obtaining the structures and damage types of buildings in earthquake stricken areas is fundamental to supporting rescue forces and estimating economic losses and casualties. As the stricken areas are often much larger than the areas covered by very high resolution (VHR) images, the information obtained from VHR images cannot satisfy practical needs. This study developed a method for estimating the structures and types of damaged buildings by combining VHR images, statistics and ground survey data. First, the rates of damaged buildings with different structures and damage types were manually interpreted from VHR images covering a small part of the stricken area, and further corrected by ground survey data. Second, the corrected rates were reallocated to the seismic intensity zones. Third, the rates in the seismic intensity zones and the statistical data were combined to estimate the numbers and areas of damaged buildings in villages, towns and counties. The presented method was applied to estimate the damages caused by the Lushan earthquake in China. The results indicated that our method can efficiently estimate the amount of the damages and complement existing work on only automatic extracting damaged buildings from VHR images.