2023年8月6日山东平原5.5级地震震源参数初步分析

北京时间2023年8月6日2时33分山东德州市平原县(37.16°N,116.34°E)发生5.5级地震,中国地震台网中心部署的预警试运行系统于震后7.5s产出首报预警结果。中国地震台网中心于震后2min发布自动速报结果,于震后10min发布正式速报结果,同时联合多家单位启动地震应急产品产出工作,共产出震源参数、历史地震、地震构造、震源机制、余震精定位、推测烈度和震源破裂过程等9类应急产品。结果显示,本次地震发生在林南断裂附近,震源机制解表明该地震为一次走滑型事件; 余震精定位结果显示余震展布呈近NEE向,与震中附近断裂方向一致; 烈度速报推测极震区烈度达Ⅷ度,区域面积约528km²,Ⅶ度及以上区域总面积约1694km²。     

澜沧—耿马地震发震构造初步研究

本文根据澜沧—耿马地震形变带、极震区及余震序列分布特征,分析了7.6和7.2级地震的发震构造,认为北北西向旱母坝断层是7.2级地震的发震构造,7.6级地震的发震构造不是一条单一的断层,北西向木嘎断裂和北北西向澜沧—勐海断裂均有明显破裂表现,这一特点与震区复杂的地质构造背景有密切联系。     

Deconvolution of squared velocity waveform as applied to the study of a noncoherent short-period radiator in the earthquake source

We consider an inverse problem of determination of short-period (high-frequency) radiator in an extended earthquake source. This radiator is assumed to be noncoherent (i.e., random), it can be described by its power flux or brightness (which depends on time and location over the extended source). To decide about this radiator we try to use temporal intensity function (TIF) of a seismic waveform at a given receiver point. It is defined as (time-varying) mean elastic wave energy flux through unit area. We suggest estimating it empirically from the velocity seismogram by its squaring and smoothing. We refer to this function as observed TIF. We believe that one can represent TIF produced by an extended radiator and recorded at some receiver point in the earth as convolution of the two components: (1) ideal intensity function (ITIF) which would be recorded in the ideal nonscattering earth from the same radiator; and (2) intensity function which would be recorded in the real earth from unit point instant radiator (intensity Green's function, IGF). This representation enables us to attempt to estimate an ITIF of a large earthquake by inverse filtering or deconvolution of the observed TIF of this event, using the observed TIF of a small event (actually, fore-or aftershock) as the empirical IGF. Therefore, the effect of scattering is stripped off. Examples of the application of this procedure to real data are given. We also show that if one can determine far-field ITIF for enough rays, one can extract from them the information on space-time structure of the radiator (that is, of brightness function). We apply this theoretical approach to short-periodP-wave records of the 1978 Miyagi-oki earthquake (M=7.6). Spatial and temporal centroids of a short-period radiator are estimated.     

成都地磁台地磁总强度数字与模拟资料对比

对成都地磁台两年多(2002~2004年)的地磁总强度数字与模拟观资料进行了对比分析,结果表明:由于数字观测资料与模拟观测资料取数的个数不同,两者的曲线变化形态不同。模拟地磁总强度的形态为近直线型,而数字化地磁总强度则有显著的日动态变化。但数字观测资料经过平均处理后产生的日均值与模拟观测日值大致相同。据现有资料,数字化地磁总强度的映震能力优于模拟地磁总强度。     

2003年甘肃民乐—山丹6.1、5.8级地震震害特点及启示

通过对2003年民乐—山丹6.1、5.8级地震震害调查资料的综合分析,阐述了本次地震震区环境背景情况,揭示了宏观地震烈度分布特征,较为全面地分析了地震的震害特点,讨论了与其相关的工程地震问题,归纳总结了防御与减轻地震灾害的经验与启示。对西部村镇工程抗震设计、施工和管理以及农村地震安居工程的规划实施等具有一定的参考价值。     

引入地震构造法的场地影响烈度地震危险性分析 --以皖西六大水库坝址为例

地震构造法是通过研究工程场地周围每一发震构造及最大潜在地震来确定场地未来的极限地震危险性。引入地震构造法，结合区域地展地质资料进行场地影响烈度地震危险性分析，将会取得更为科学可靠的结果。本文以皖西六大水库坝址为例，考虑地震构造条件，进行场地影响烈度地震危险性分析，给出50年P(I≥i)＝10％的分析结果。研究结果表明，发震构造及最大潜在地震对周围场地未来地震危险性具有明显的控制作用。     

Computer estimation of intensities: The 1985 Berhida,Hungary, earthquake

In this paper a computerized method for the intensity estimation from macroseismic observations is presented. The successive steps of the MSK intensity scale (2° to 10°) receives weights according to the observations marked on the earthquake questionnaires. These weights are summed for the individual scale steps. The distribution of these summed weights and their relation to an experimentally chosen function of the criterion make it possible to estimate the appropriate intensity value and its reliability. By computer evaluation of earthquake reports an objective comparison of estimated intensities given by different seismologists can be made, provided that uniform earthquake questionnaires are used. The application of this method will result in more homogeneous intensity data.     

近断层地震动作用下钢筋混凝土桥墩的抗震性能

通过对满足规范延性要求的12根典型钢筋混凝土桥墩试件的线性和非线性地震反应分析，指出在近断层地震动作用下满足延性需求与延性能力比小于1.0的桥墩仍可能发生严重破坏和倒塌，若考虑桥墩的地震损伤性能，允许的延性需求与延性能力比不宜超过0.6-0.8。讨论了桥墩延性抗震设计中强度折减系数Rμ和设计基底剪力系数BSC取值问题。     

Characterization of differential throughfall drop size distributions beneath European beech and Norway spruce

Forest canopies present irregular surfaces that alter both the quantity and spatiotemporal variability of precipitation inputs. The drop size distribution (DSD) of rainfall varies with rainfall event characteristics and is altered substantially by the forest stand properties. Yet, the influence of two major European tree species, European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst), on throughfall DSD is largely unknown. In order to assess the impact of these two species with differing canopy structures on throughfall DSD, two optical disdrometers, one above and one below the canopy of each European beech and Norway spruce, measured DSD of both incident rainfall and throughfall over 2 months at a 10‐s resolution. Fractions of different throughfall categories were analysed for single‐precipitation events of different intensities. While penetrating the canopies, clear shifts in drop size and temporal distributions of incoming rainfall were observed. Beech and spruce, however, had different DSD, behaved differently in their effect on diameter volume percentiles as well as width of drop spectrum. The maximum drop sizes under beech were higher than under spruce. The mean ± standard deviation of the median volume drops size (D50) over all rain events was 2.7 ± 0.28 mm for beech and 0.80 ± 0.04 mm for spruce, respectively. In general, there was a high‐DSD variability within events indicating varying amounts of the different throughfall fractions. These findings help to better understand the effects of different tree species on rainfall partitioning processes and small‐scale variations in subcanopy rainfall inputs, thereby demonstrating the need for further research in high‐resolution spatial and temporal properties of rainfall and throughfall.     

The historic evolution of Zhouyuan and the newest activity of the great Wei River fault

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