中国地震台网波形数据整理及服务平台建设

对中国地震台网中心2008—2021年间存储的中国地震台网固定观测台站近150TB波形数据进行了归档和整理,并对数据可用率和断记缺失情况进行了调查统计。在建立波形文件索引数据库的基础上,建设了符合国际标准Web服务接口的波形数据服务平台,能够7×24h不间断提供数据服务,实现了用户通过应用程序自动获取定制波形数据的功能,为人工智能等新数据驱动技术在地震监测中的发展应用提供了支撑。     

用于地震预警的三维实时定位方法

为了尽快定位地震,在“着未着”定位算法基础上,尝试引入三维地壳模型,构建具有三维空间格点分布的走时表.根据已触发台站的到时和未触发台站的位置信息设计概率分布函数,通过八叉树搜索方法,快速给出震源在三维空间的可能位置.使用波前追踪算法,计算中国几个地区三维地壳模型的走时网格,利用中国地震台网资料,对区域内发生的地震进行定位分析.结果显示,在一定的台网密度条件下,三维实时定位方法能在震后数秒给出震源位置,可满足地震预警要求.     

Geochronology and geochemistry of the Donglufang porphyry-skarn Mo-Cu deposit in the southern Yidun Terrane and their geological significances

The newly-discovered Donglufang Moe Cu porphyry-skarn deposit is located in the southern Yidun Terrane, southeast Tibet, with more than 80 million tonnes(Mt) of reserves(grading 0.15 wt.% Mo and0.48 wt.% Cu) hosted in Triassic strata and Late Cretaceous granodiorite porphyry. Ree Os dating of molybdenum ore yielded a weighted mean age of 84.9 ± 1.0 Ma and an isochron age of 85.2 ± 0.6 Ma.LA-ICP-MS Ue Pb dating of zircons from the granodiorite porphyry yielded206 Pb/238 U ages ranging from 87.4 Ma to 84.2 Ma with a weighted mean206 Pb/238 U age of 85.1 ±0.5 Ma, indicating a temporal linkage between granitic magmatism and Moe Cu mineralization. Geochemical analyses show that the granodiorite porphyries are I-type granites with Si O_2 contents of 64.3 -66.7 wt.%. These rocks are typically metaluminous with high K_2 O/Na_2 O ratios, low Mg O(1.32 -1.56 wt.%), Cr(5.6 -12.9 ppm), Ni(3.79 -10.81 ppm), Mg#(43 -52) values, and high Sr(304 -844 ppm), Sr/Y(21.2 -50.8) and La/Yb ratios(37.0 -60.1). They are enriched in light rare-earth elements(LREE) relative to heavy rare-earth elements(HREE), with slightly negative Eu anomalies, and are enriched in Th, U and large ion lithophile elements(LILE, e.g., K and Rb), and depleted in high field strength elements(HFSE, e.g., Nb, Ta, P and Ti). They also show negative zircon εHf(t) values(-6.7 to -2.3) and negative whole rock εNd(t) values(à5.2 to-4.3), as well as old Hfe Nd model ages, indicating the magmas were derived from a thickened ancient lower crust within the garneteamphibolite facies. Considering the tectonic evolution of the Yidun Terrane, geochemical characteristics of granodiorite porphyry, and the ages of mineralization obtained in this study. We suggest that the Donglufang deposit was formed in a post-collisional setting, which has a genetic relationship with the emplacement of the granodiorite porphyry. The present study provide key information for the exploration of the Late Cretaceous metallogeny in the Yidun Terrane.     

一种基于窗口查询的空间选择率估算方法

针对任意空间查询区域提出了一种基于CD直方图选择率的估计方法,确定了影响空间点(x,y)直方图估计值的相关格子,并对其中确定的部分直接引用,对于不确定的部分则充分利用格子提供的信息进行了修正,从而可以较为精确地计算出空间点(x,y)的估计值,为提高查询选择率估计值的准确性奠定了基础。     

利用Virtual Quake地震模拟器研究鲜水河断裂带地震活动性与地震复发周期

2022年9月5日四川泸定6.8级地震发生在鲜水河断裂带磨西断裂上。本文依据鲜水河断裂带的断层几何形态、断层面物理力学参数、断层滑移速率等基础资料,构建断裂带三维模型,基于Virtual Quake地震模拟器开展鲜水河断裂带准静态数值模拟。对七条分支断裂独立模拟的结果显示模拟结果与历史地震的最大震级和复发周期具有较好的一致性。结果表明模型长度影响震级大小,滑移速率影响地震复发周期。断层面几何弯曲展布使得断层面应力分布不均匀,在弯曲处出现应力积累的现象,易触发地震,并出现了地震分段破裂现象,降低了几何弯曲断层的地震频次,为强震的孕育创造了条件。联合模拟的10000年时间内,鲜水河断裂带共发生了33次M≥7.0地震,最大震级为M7.6,地震活动性呈现一定的活跃期与平静期。断层系统地震间的相互应力作用和复杂的断层几何结构影响着地震迁移的复杂性。道孚断裂上相距40年发生两次M≥7.0地震,乾宁断裂北端相距5.8年发生M≥7.0双震,此类现象与历史地震有一定的相似性。     

时序数据库在海量地震波形数据分布式存储与处理中的应用初探

通过分析时序数据库的技术特点和海量地震数据存储和处理的需求,设计和实现了基于时序数据库的地震波形数据存储和处理系统。经过开发、测试和应用比较,新的地震时序数据库系统具有高可用、实时存储吞吐量大、历史数据压缩率高、分布式处理速度快等优势,能够较好地解决地震波形数据体量激增带来的存储和处理困难问题。     

SLC Analysis on Earthquake Activity in the Regions of Sichuan and Yunnan of China

Using the method of Single-link Cluster(SLC),analyzing the pattern of time sliding of SLCparameters,the earthquake activity in the western Sichuan-Yunnan of China is studiedcombining with the regional earthquake catalogue since 1970 and the tectonic background.Comparing with the high level of earthquake activity in 1970’s and the low in 1980’s,theearthquake activity is in general at the middle level in 1990’s.This paper suggests that SLCmethod,which considers the temporal and spatial relationship among earthquake events,could be adopted to analyze the trend of regional earthquake activity,it is very useful forstudying seismic activity.     

A note on the equivalence of three major propagator algorithms for computational stability and efficiency

It is shown in this note that the three methods, the orthonormalization method, the minor matrix method and the recursive reflection-transmission matrix method are closely related and solve the numerical instability in the original Thomson-Haskell propagator matrix method equally well. Another stable and efficient method based on the orthonormalization and the Langer block-diagonal decomposition is presented to calculate the response of a horizontal stratified model to a plane, spectral wave. It is a numerically robust Thomson-Haskell matrix method for high frequencies, large layer thicknesses and horizontal slownesses. The technique is applied to calculate reflection-transmission coefficients, body wave receiver functions and Rayleigh wave dispersion.     

我国地面气温极值和地面风速极值的渐近分布

利用1951—1982年期间我国173个测站的地面最高气温年极值记录,158个测站的地面最低气温年极值记录和83个测站的地面最大风速年极值记录,通过统计推断,找出了我国地面最高、最低气温年极值和地面最大风速年极值遵循的渐近分布——Weibull分布和Gumbel分布,并简要讨论了它们的形状。