智利高地震烈度区高压瓷瓶隔离开关的高等级抗震考核试验

为获取户外高压隔离开关的动态特性、研究瓷瓶破断力与地震载荷的关系以及验证隔离开关的抗震性能,开展了相关的考核试验。依据IEEE 693—2005标准的要求,试验前进行了应变计的校准试验、瓷瓶的弯曲破断试验和隔离开关的抗震性能试验。经过抗震试验,隔离开关完好无损且在抗震试验前后其共振频率变化不大,瓷瓶破断力大于地震载荷的2倍。结果表明隔离开关结构稳定,通过了抗震考核。     

Dynamics of interaction between fields of seismicity and surface deformations (Bishkek geodynamic test area)

The spatial-temporal dynamics of surface crustal movements revealed from GPS data is compared with seismicity in the Bishkek geodynamic test area documented in the regional KNET catalog. The geological information system (GIS) GeoTaim 2.0 is substantially improved, which allowed variations in seismicity and deformation fields to be analyzed in the 3D raster. It is shown that seismicity and surface deformations are correlative in the test area. The periods with extreme values of contraction and the extension rates of the Earth’s surface areas are accompanied by enhanced seismicity and strong earthquakes. The increase in the spatial gradient of surface crustal movements coincides with changes in the azimuths of compression axes indicated by mechanisms of earthquakes that occurred at depths of up to 25 km. For a better geological—geophysical interpretation of interactions between deformation and seismicity fields in the Bishkek geodynamic test area, the spatial system GPS stations and measurement frequency need substantial improvement.     

山西太原东山地震台附近地区地震尾波Qc值变化特征研究

采用Aki单次散射模型,用太原东山地震台记录到的ML2.0~5.0地震,计算得到Qc值随频率的变化结果。得出,随着尾波窗长增大,平均采样体深度增加,Q0值增大,η值减小。当尾波窗长取20 s时,Q0值为70.1,η值为1.03,是东山台附近地区最佳的研究结果。     

A Catalogue of Earthquakes With Moment Magnitude of the Center-Southern Asia Test Area of the Global Seismic Hazard Assessment Program

We compile a regional catalogue of earthquakes with moment magnitude of the Center-Southern Asia test area(20°-35°N,85°-105°E)for the Global Seismic Hazard Assessment Program(GSHAP).There are significant inhomogeneous and uncompleted data,and n uniformity of earthquake magnitudes in this test area because this region is situated on the boundaries of many countries,such as China,India,Nepal,Vietnam,etc.We establish a relationship between Gutenberg surface-wave magnitude and IASPEI surface-wave magnitude,which can be used for conversion of different magnitude scales into moment magnitude for this catalogue.A catalogue of events with Mw≥6.0 of this test area is given at the end of this paper.     

Climate change impacts on runoff in the Ferghana Valley (Central Asia)

The main freshwater source of arid/semi-arid Central Asia is stored in its high mountain glaciers. Water for the downstream countries is mainly supplied through the Syrdarya River that originates at the confluence of the Naryn and Karadarya rivers in the Ferghana Valley. Runoff generation from glaciers plays a crucial role, although a considerable number of small tributaries supply the river with additional runoff from snowmelt and rain in the mountains surrounding the Ferghana Valley. Observations of rising air temperature and accelerated glacier shrinkage make it most likely that the relative contributions of the smaller tributaries will increase. Hitherto, assessments of climate change effects on the water resource availability have largely neglected the growing importance of the runoff from smaller tributaries. We used a dynamically downscaled A1B SRES scenario for climate change effects for the period 2071–2100 in relation to the reference period of 1971–2000 and a version of the conceptual hydrological Hydrologiska Byråns Vattenavdelning model (HBV-light) to estimate runoff contributions with particular respect to the small tributaries. The simulations showed a 12–42% decrease in summer runoff; and a 44–107% increase in winter-spring runoff. This indicates the hydrological regime is shifting towards a runoff from snowmelt earlier in the year. The study suggests that actions for climate change adaptation should be complemented by land management configured to secure optimal runoff supplement from the smaller catchments.     

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

Izvestiya, Physics of the Solid Earth - Abstract—Analysis of P- and S-receiver functions for 19 seismic stations on the Balkan Peninsula has been performed. Half of the stations are in...     

Influence of Nonlinear Processes in Seismic Foci on Released Energy

—The results of the frequency analysis of seismoacoustic elastic waves radiated from the loaded rock sample source models and of rock bursts records are presented. For both categories of study the fundamental symptoms of nonlinear processes in seismic foci were found and demonstrated. Namely, the wave-field modulation (satellites in the spectra), forced synchronisation (spectra simplification and their transformation into a narrow spectral band), frequency shift to lower values and, finally, coherency of radiation. A new method of amplitude-phase distribution is worked out. All this indicates that nonlinear processes can participate in a seismic source during the energy release. Also, the disagreement between the source sizes observed in the nature and computed by means of linear physics, can be explained by self-organising processes.     

Seismic characterization and monitoring of Fucino Basin (Central Italy)

The Fucino basin (Central Italy) is one of the largest intramountain alluvial plain in the Apennines range. It has a tectonic origin related to the presence of important systems of faults located in its northern and eastern edges. Some of these faults are still active and capable of generating strong seismic events. Site effects related to the soft soils filling the basin can be very important. In this paper we show the preliminary results of a seismic network installed in the Fucino area in order to collect information about site amplification effects and geometry of the basin. We analyze ambient seismic vibrations and recordings of about 150 local earthquakes mainly related to the seismic sequence of the April 6th 2009 Mw 6.3 L’Aquila event. Moreover the strongest events of L’Aquila sequence were analyzed at the three permanent strong-motion stations operating in the area. Using standard spectral techniques we investigate the variation of resonance frequencies within the basin. The ground motion recorded in the Fucino plain is mainly characterized by strong energy at low-frequencies (f < 1 Hz) affecting both horizontal and vertical components. This is particularly evident for stations deployed in correspondence of very thick deposits of sedimentary filling, where a significant increase of ground-motion amplitude and duration is likely caused by locally generated surface waves. The amplification at low-frequencies (<1 Hz) on the horizontal components can reach up a factor of 10 in comparison to nearby stiff sites. However, we found evidences of seismic amplification phenomena also for stiff sites surrounding the basin, including stations of the Italian strong motion network. The independent geological information and the shallow shear-velocity profiles available for the basin can be combined with resonance frequencies for deriving representative geological sections to be used as base for future numerical 2D–3D modeling of the basin.     

东亚大陆大三角地震区的强震成组活动迁移图像分析

本文分析了1900—2008年东亚大陆大三角地震区7.5级以上大地震的地震活动时空图像, 认为: ① 1902—1974年东亚大陆大三角地震区的7.5级以上浅源地震成组活动的主体地区, 沿着大三角地震区的边界顺时针迁移, 到了1997—2001年开始转移到大三角地震区的内部; ② 对于整个大三角地震区而言, 近代7.5级以上浅源地震的震级(M)-时间(t)过程表明, 地震活动是活跃和平静交替出现的幕式过程; ③ 大三角地震区近代7.5级以上浅源地震的时空迁移图像的力学机制, 可能是地震区内地震断层应力转移和耦合的相互作用。     

Probabilistic PGA and Arias Intensity maps of Kyrgyzstan (Central Asia)

New probabilistic seismic hazard and Arias Intensity maps have beendeveloped for the territory of the Kyrgyz Republic and bordering regions.Data were mainly taken from the seismic catalogue of Kyrgyzstan and partlyfrom the world seismic catalogue. On the base of seismicity and activetectonics, seismic zones were outlined over the area. For these,Gutenberg-Richter laws were defined using mainly instrumental data, butregarding also historical events. Attenuation of acceleration inside the targetarea could not be determined experimentally since existing strong motiondata are insufficient. Therefore, empirical laws defined for other territories,principally Europe and China, were applied to the present hazardcomputations. Final maps were calculated with the SEISRISKIII programaccording to EUROCODE8 criteria, i.e. for a period of 50 years with90% probability of non-exceedance. For long-term prediction, 100 yearsmaps with 90% probability of non-exceedance have been developed. Theprocedure used for seismic hazard prediction in terms of PGA (PeakGround Acceleration) was also applied to Arias intensities in order to beable to define regional seismogenic landslide hazard maps.     

Stress Changes due to Recent Seismic Events in the Central Apennines (Italy)

The Central Apennines, Italy, are characterized by moderate seismic activity on normal faults, oriented in directions parallel to the Apenninic chain. The subject of this study is the Umbria-Marche Apennines, a segment approximately 200-km long, where three main seismic events occurred in the last three decades. The 1979 Norcia earthquake was a M_w = 5.8 event, taking place at the south end of the considered segment. The 1984 Gubbio earthquake was a M_w = 5.6 event which took place at the north end. The 1997-1998 Colfiorito sequence constituted 8 main shocks with magnitudes M_w between 5 and 6 and epicenters located between the Gubbio and the Norcia earthquake areas. A model made of an elastic half-space is considered, in which the seismic sources are represented by rectangular dislocations which have the appropriate values of source parameters, and in which the static stress field produced by each event is calculated. The analysis of the Coulomb stress change (ΔC) as a function of time shows that the coseismic stress transfer and fault interaction played an important role in the region during the past three decades: 7 earthquakes of the 9 considered took place where ΔC>0. Such an interaction has been confirmed by the analysis of the aftershocks in the Colfiorito zone post September 26, 1997: about the 61% of the aftershocks considered took place where ΔC>0. The comparison between the ΔC^s due to the coseismic stress transfer and the rate ΔĊ^t due to the tectonic stress allows us to quantify the time advance of the earthquakes. The ΔC^s pattern shows positive values in two areas that can be regarded as historical seismic gaps.     

地震波斜入射对高面板坝地震反应的影响

为研究地震波斜入射对高面板坝地震反应的影响,根据地震波动入射理论,采用FORTRAN进行波动荷载的编程计算,并与大型通用有限元软件ADINA相结合,实现基于黏弹性人工边界的地震波斜入射,研究P波和SV波分别以不同角度入射对高面板堆石坝地震反应的影响。结果表明,地震波斜入射时大坝地震动反应与垂直入射时明显不同,常规垂直入射的结果偏于不安全,因此在高面板坝地震反应分析和抗震设计中应考虑地震波斜入射的影响。     

Seismic expression of active extensional faults in northern Umbria (Central Italy)

This paper deals with the geometry and kinematics of the active normal faults in northern Umbria, and their relationship with the seismicity observed in the area. In particular, we illustrate the contribution of seismic reflection data (a network of seismic profiles, NNW–SSE and WSW–ENE trending) in constraining at depth the geometry of the different active fault systems and their reciprocal spatial relationships. The main normal fault in the area is the Alto Tiberina fault, NNW trending and ENE dipping, producing a displacement of about 5 km, and generating a continental basin (Val Tiberina basin), infilled by up to 1500 m with Upper Pliocene–Quaternary deposits. The fault has a staircase trajectory, and can be traced on the seismic profiles to a depth of about 13 km. A set of WSW-dipping, antithetic faults can be recognised on the profiles, the most important of which is the Gubbio fault, bordering an extensional Quaternary basin and interpreted as an active fault based on geological, geomorphologic and seismological evidence. The epicentral distribution of the main historical earthquakes is strictly parallel to the general trend of the normal faults. The focal mechanisms of the major earthquakes show a strong similarity with the attitude of the extensional faults, mapped at the surface and recognised on the seismic profiles. These observations demonstrate the connection between seismicity in the area and the activity of the normal faults. Moreover, the distribution of the instrumental seismicity suggests the activity of the Alto Tiberina fault as the basal detachment for the extensional tectonics of the area. Finally, the action of the Alto Tiberina fault was simulated using two dimensional finite element modelling: a close correspondence between the concentration of shear stresses in the model and the distribution of the present earthquakes was obtained.     

Effect of sub-cloud evaporation on precipitation in the Tianshan Mountains (Central Asia) under the influence of global warming

It is crucial for accurately describing the precipitation patterns and their underlying mechanisms to optimise the hydro-climatic model parameters and improve the accuracy of precipitation forecasting. Based on 212 precipitation samples collected during August 2015 to July 2016 in the mid-mountain region of the Manasi River Basin in the northern slope of the Tianshan Mountains, we estimated the effect of sub-cloud evaporation on precipitation, analysed the factors that influence the sub-cloud evaporation, and modelled the response of sub-cloud evaporation to global warming. The mean remaining raindrop mass fraction after evaporation (f ) in this region is 94.39%. The mean deviation between d-excess (Δd ) of ground precipitation and raindrops under cloud is −4.22‰. The intensity of sub-cloud evaporation is the highest in summer. There is a significant positive correlation between f and Δd (0.72‰/%). The relative humidity and diameter of raindrops were observed to have a direct influence on the intensity of sub-cloud evaporation. The temperature was observed to influence the intensity of sub-cloud evaporation indirectly by influencing the relative humidity and diameter of raindrops. Global warming will increase the intensity of sub-cloud evaporation in the Tianshan Mountains, especially for small precipitation events.     

Site Response for the RSM Seismic Network and Source Parameters in the Central Apennines (Italy)

—?Thirty-three earthquakes which occurred in the Central Apennines (Italy) with Ml ranging from 2.4 to 3.7 have been spectrally analysed using digital recordings from twelve stations of the Rete Sismometrica Marchigiana (RSM) network. Data corrected for geometrical spreading and quality factor Q have been inverted by means of the Generalised Inversion Technique. Site responses have been compared with those obtained by H/V ratio. Site amplifications have been observed both at stations placed on Pleistocene sediments and at one station located at 1800?m altitude. Source parameters have been calculated by fitting the spectra with an automatic procedure adopting the ω² source model. The seismic moments range from 9.23?×?10¹⁹ to 4.28?×?10²¹ dyne-cm with an average M ₀ (S) to M ₀ (P) ratio of 1.13?±?0.38. The stress drops are generally low and they vary between 1.1 and 10.2?bar when estimated by using S source spectra, and between 0.5 and 7.1?bar when the P-source spectra are fitted. For the considered range of seismic moments we observe that the stress drop does not have significant dependence on event size.     

Seismic Source Classification by Means of a Sonogram- Correlation Approach: Application to Data of the RSM Seismic Network (Central Italy)

—?In this paper, we apply a new sonogram correlation approach for seismic source classification. In order to test the technique, we use the waveforms recorded by 6 among 16 of the stations of the Rete Sismometrica Marchigiana (RSM) network, relevant to the vertical component of 365 earthquakes that occurred in the analyzed area from April 1996 until September 1999. All the sonograms of each station are cross-correlated in a single station procedure and the calculated degrees of resemblance are used to classify the events by means of a bridging technique. The results obtained with the single-station approach are integrated into a network classification. We identified three families in the investigated area. Once the efficiency of the method is tested, we analyzed the families obtained for the selected subset of events. Considering the temporal and the spatial distribution of the events forming each family, we classified them as quarry blasts. This classification, even if relevant to a subset of earthquakes occurring in Central Italy, modifies the present knowledge of the seismicity distribution in the area and allows estimation of the errors affecting the hypocenter locations provided by the RSM network. An extension of this new technique to the whole Central Italy earthquake catalog promises an interesting review of the seismicity in the area.     

地震前兆场的演化和能量非线性聚集的关系

运用非均匀介质中“非线性振动的局域能量聚集”过程,模拟唐山７．８级和大同６．１级地震的前兆场演化,发现地震孕育过程中出现的诸多前兆特征与地壳内构造能量的非线性聚集有关。     

滇西北至滇南强震危险区地震活动能量场分析

运用随机函数理论,将滇西北至滇南地区的地震活动能量场看作时间和空间的随机函数,用自然正交函数展开方法,研究主要能量场的时间权重系数变化曲线、空间等值线图和研究时段内的均值能量场空间分布.结果发现,能量场的时间权重系数变化曲线较大幅度的升、降变化异常预示了可能发生强震的时间段,而等值线图的高值变化异常对应了可能发生强震的...     

基于数学去噪后模拟地震信号测试混凝土结构抗震性能的研究

针对当前混凝土结构建筑抗震性能测试方法存在的测试结果准确率较低的问题,提出一种新的测试方法,利用小波函数的伸缩平移操作得到一个函数族,对模拟地震信号进行小波变换。当函数族组成一个标准的正交基时,从连续小波变换中对地震信号进行重构,将去噪后的地震信号作为检测混凝土结构建筑抗震性能的信号样本。利用单自由度体系的动力平衡方程对地震的位移反应、速度反应加速度反应以及恢复力进行求解,通过强度折减系数计算公式和结构最大弹性反应计算公式,计算混凝土结构建筑的强度折减系数和结构最大弹性反应,最后在震动台上对混凝土结构建筑抗震性能进行测试。测试实验结果表明,所提方法可以实现对混凝土结构建筑抗震性能的测试,且测试结果准确程度较高。     

Ⅶ度抗震设防下牧区居住建筑节能技术研究

对抗震设防下的牧区居民建筑进行节能设计,在提高能源利用率及降低能源消耗方面具有重要意义。传统的建筑节能技术主要通过降低建筑的热能消耗来提高能源利用,存在节能效果差且单一的问题。对此,在Ⅶ度抗震设防下,采用ANSYS软件,引入Block Lanczos法对牧区居住建筑结构的模态进行分析,计算出建筑地震作用,并通过分析牧区居住建筑围护结构及门窗材质来优化建筑节能技术。实验结果表明,在内蒙古牧区居住建筑采用改进提出的建筑节能技术,可有效降低能源消耗,从而能够有效利用能源,使其具有一定的优势。