一种地震预警监测传感器模块的设计及实现

目前世界上地震预警系统基本都是通过地震台网来确定地震的震级并对地震进行定位,其预警准确性的提高主要依靠台网密度的增加。基于地震预警原理以及传感器技术,本文首次探讨了仅用单台地震监测传感器快速测定地震基本参数的可能性。设计了一种用于地震预警的地震监测传感器模块,阐述了确定地震参数的算法。该传感器模块能自动捡拾P波的到时,然后利用P波的初动信息确定地震的方位角,最后利用P波到达后前3s加速度数据确定地震的震级、震源距,并发出警告,达到地震监测及预警的目的。     

基于人工神经元网络和多特征参数的预警震级估算

预警震级测定是地震预警的关键技术环节之一。在满足地震预警系统时效要求的前提下,以国内现有的人工神经元网络构架为基础,考虑采用更多的特征参数,对实时持续计算确定预警地震震级的方法进行研究。通过对日本部分实际强震数据进行持续估算预警震级与实际震级间的偏差情况,对预警震级和实际震级进行线性拟合,提出对预警震级结果的修正公式,进一步完善本方法快速估算预警震级的准确程度。     

基于汶川主震及余震的一种新型地震预警震级估计参数τ_(log)研究

我国四川地区在2008年发生了一次面波震级达8.0级的强烈大地震,诱发了多处灾难性滑坡灾害并造成了重大人员伤亡.作为防震减灾最为行之有效的方法之一,地震预警系统亟待在四川地区建立起来.在地震预警系统中,对地震震级的快速估算是最为重要且困难的工作之一.目前世界上提出较早、应用较为广泛的快速震级估计的参数主要有:最大卓越周期(τ_p~(max))、特征周期(τ_c)和最大位移幅值(P_d).本文介绍了一种新型的震级估计参数对数周期(τ_(log))并利用2008年汶川主震及其余震P波和S波初期部分的信息,研究了该参数与震级的相关性,并与前人研究同为周期/频率相关算法的τ_p~(max)和τ_c参数进行对比,然后进一步研究时间窗口长度对震级估计误差的影响并进行了评价.结果表明:对于主震事件(M 8.0),短时窗的τ_(log)参数无法避免震级低估(震级饱和)现象,当时间窗口到达第5s时,震级饱和现象能有效地被克服;对于中等震级地震事件(M 5.0~6.5),能够较好地反映地震规模大小,震级估算误差能较好地满足地震预警系统精度要求;在小震级事件(M5.0)中,τ_(log)方法的震级估计误差更小,相比起τ_c方法显得更为优越,在地震预警系统的实际应用中,能够有效地降低对于小震事件的误(漏)报率.     

西西里岛东部地震预警参数评估

地震预警系统正在成为适用于实时地震风险管理的一个工具。事实上,由于地震预警系统是在短时间内减轻地震风险的有效方法,因此在全球许多国家已经实施或正在进行试验。地震预警系统是以利用震后地震信号初始部分测量的一些参数之间的关系为基础的。本文我们介绍了在西西里岛东部为实施地震预警系统的初步探索,该地区遭受了几次破坏性地震的袭击。使用意大利国家地球物理和火山研究所的宽频带台站记录的M_L≥2.8的地震数据,我们估算了P波和S波的初至波的峰值地动位移Pd,地面运动周期τ_c和峰值地动速度(PGV)。我们发现P_d与地震的大小有关,可以用来为该地区的地震预警系统估算震级。我们还推导了τ_c和ML之间以及P_d和PGV之间的关系,这些关系可以用于给定台站周围的现场预警,并评估潜在的破坏性影响,这些关系可能对未来在该地区实施地震预警系统有实际的参考意义。     

地震预警震级确定方法研究

地震预警技术是减轻地震灾害损失的有效手段之一．地震预警系统中,地震震级计算是最重要也是最困难的部分之一．利用日本KiK-net台网和四川汶川余震共142次地震事件的记录,分别采用tau;c和Pd方法统计得到了地震预警震级的计算公式,震级计算的方差分别为0.62和0.56个震级单位．为消除震级计算过程中出现的震级饱和现象,作者拓展了Pd方法,提出了一套对位移幅值连续追踪测定的算法．当时间窗长度为10 s时,采用该方法的震级计算方差仅为0.37个震级单位,充分满足地震预警系统的需求．同时,该方法也实现了信息的连续过渡,提高了对现有信息的利用率．最后,还对位移幅值Pd用于地震动峰值PGV的估计以及不同特征参数间的相容性等内容进行了讨论．      

地震预警震级计算方法研究综述

地震预警系统是减轻地震灾害的有效手段之一,世界上多个国家和地区都已经建立了地震预警系统,并在实际应用中取得了显著的减灾实效.由于地震预警系统应用中的高度时效性要求,预警震级计算是整个地震预警系统中最重要也是最困难的一部分.本文回顾总结了地震预警研究中采用的一些震级计算方法,并将其归纳为三大类算法:与初始周期相关的算法、与初始幅值相关的算法和与初始强度相关的算法.对每种算法都做了详尽介绍和仔细分析,同时列举出与该算法相关的研究成果.通过对这些算法的分析总结并结合我国地震观测台网的实际情况,作者推荐τc、Pd两种方法作为我国地震预警系统建设中优先采用的两种预警震级算法.     

高频GNSS实时地震学与地震预警研究现状

为实现从注重灾后救助向注重灾前预防转变,如何提高地震灾害监测预警和风险防范能力成为我们关注的重点.本文给出了国际上GNSS位移记录、强震动加速度记录、测震速度记录在地震预警中的应用现状,并总结了各自的特点,归纳出围绕高频GNSS地震学在震级与破裂过程实时反演中的几个需要进一步研究的关键问题：（1）引入北斗系统,基于高频GNSS（GPS/BDS）双系统的实时位移解算方法来提高实时单站位移解算精度,使实时解算精度达到厘米级;（2）开展强震仪加速度记录基线偏移校正研究,弥补地震近场GNSS站密度不足问题;（3）强震仪加速度记录与GNSS位移记录特点不同,开展强震仪加速度数据与GNSS位移数据实时融合处理研究,快速获得包含丰富地震形变和速率的波形数据;（4）测震学方法可快速估算震级,但是在强震发生时会出现震级饱和现象,造成震级估算偏低.需要开展基于GNSS位移时间序列的多种方法相结合的实时震级估算方法研究,通过与地震学方法比较和结合,来得到精度高、计算快的震级估值算法;（5）基于高频GNSS、断层初始模型快速选取、断层尺度、参数自适应调整是快速判断断层破裂方向的基础,在断层破裂过程自适应准实时反演算法方面需要进一步加强.通过国内外研究现状调研、分析,表明基于高频GNSS地震学的震级快速确定、震源破裂过程准实时反演算法的发展将对我国地震预警系统从"二网融合"到"三网融合"提供坚实的技术支撑.     

淮北地震台中强震面波震级偏差修正

整理校正淮北地震台测震编目资料面波震级M_S 4.5及以上中强震震例,以中国地震台网中心(简称CENC)发布的震级参数作为标准震级,分析CENC震级与淮北地震台单台分析结果中的发震时刻、震中经纬度、震级、方位角、震中距等参数之间线性相关关系,建立CENC震级关于单台分析结果的多元线性回归方程,用于淮北地震台记录的中强震面波震级偏差修正。检验结果显示,该修正方法有效、可信。     

淮北地震台中强震面波震级偏差修正

整理校正淮北地震台测震编目资料面波震级MS4．5及以上中强震震例,以中国地震台网中心（简称CENC）发布的震级参数作为标准震级,分析CENC震级与淮北地震台单台分析结果中的发震时刻、震中经纬度、震级、方位角、震中距等参数之间线性相关关系,建立CENC震级关于单台分析结果的多元线性回归方程,用于淮北地震台记录的中强震面波震级偏差修正。检验结果显示,该修正方法有效、可信。     

日本新干线地震监测与预警系统

地震是一种对高速铁路行车安全危害极大的自然灾害,为了减轻地震对高速铁路造成的灾害,建设高速铁路地震监测与预警系统是一项行之有效的手段。详细介绍了较为成熟的日本新干线地震监测与预警系统的发展历史、系统组成、紧急处置流程、报警方式、震源参数与紧急处置范围的确定方法,以及该系统在2011年3月11日东日本大地震中的紧急处置过程,旨在为中国高速铁路地震监测与预警系统的研究与建设提供参考和借鉴。     

Use of mode-converted waves in marine seismic data to investigate the lithology of the sub-bottom sediments in Isfjorden,Svalbard

The compression wavefield is efficiently converted to shear-wave energy at post-critical angles in areas of high impedance contrast at the sea floor. We have analysed mode-converted shear waves in a data set acquired with a hybrid marine/land geometry in Isfjorden, Svalbard. Through a kinematic 2D ray-tracing modellingV _p/V_s ratios for part of the uppermost 5km of the crust are obtained. Low values (V _p /V _s =1.65) are tentatively associated with the section of Devonian sandstones which appears to attain a minimum thickness of 1.5km below 3 km depth about 10km west of Kapp Thorden.     

Moment Magnitude and Its Calculation

In this paper, we give a brief introduction to the proposal and development history of the earthquake magnitude concept. Moment magnitude M_W is the best physical quantity for measuring earthquakes. Compared with other magnitude scales used traditionally, moment magnitude is not saturated for all earthquakes, regardless of big and small earthquakes, deep and shallow earthquakes, far field and near field seismic data, geodetic and geological data, moment magnitude can be measured, and can be connected with well-known magnitude scales such as surface wave magnitude M_S. Moment magnitude is a uniform magnitude scale, which is suitable for statistics with wide magnitude range. Moment magnitude is the preferred magnitude selected by the International Seismological community, and it is preferred by the departments responsible for publishing seismic information to the public.Moment magnitude is a uniform magnitude scale, which is suitable for statistics with wide magnitude range. Moment magnitude is a preferred magnitude for international seismology, it is preferred by the agency responsible for providing information about earthquakes to the public. We provide all formulas used in the calculation of moment magnitude, and the calculation steps in detail. We also analyzed some problems and rules to solve these problems by using different formulas and numerical value calculation steps.     

The Key Technical Points and Main Characteristics of the New National Standard of Magnitude

The New Magnitude National Standard of General Rules for Earthquake Magnitude( GB17740-2017) is the state mandatory standard. It was released on May 12,2017,by the General Administration of Quality Supervision,Inspection and Quarantine of the Peoples Republic of China and the Standardization Administration of the Peoples Republic of China. This paper introduces the necessity of revising the national standard of magnitude,and the main contents,technical points and primary features of the new national standard of magnitude,so that it can be applied better in practice.     

甘肃近期几次中强地震震源机制解

12002年12月14日玉门MS5.9地震发震时间:21∶27′27″;经纬度:39.8°N,97.3°E;深度:33km;震级:MS5.9。收集了全省及邻近省份共同31个台站初动后作出震源机制解(表1,图1)。表1　玉门MS5.9地震震源参数节面A节面BP轴T轴N轴矛盾比/%走向倾角滑动角走向倾角滑动角方位角仰角方位角仰角方位角仰角147°26°35°24°75°111°277°27°140°55°18°21°0.09722003年10月25日民乐-山丹MS6.1地震发震时间:20∶41′36.4″;经纬度:38.33°N,100.95°E;深度:12km;震级:MS6.1。收集了全省21个台站初动后作出震源机制解(表2,图2)。表2　民乐-山…     

Vp and Vp/Vs structures in the crust and upper mantle of the Taiwan region, China

A tomographic study of the V _p and V _p/V _s structures in the crust and upper mantle beneath the Taiwan region of China is conducted by simultaneous inversion of P and S arrival times. Compared with the previous tomographic results, the spherical finite difference technique is suitable for the strong heterogeneous velocity structure, and may improve the accuracy in the travel time and three-dimensional ray tracing calculations. The V _p and V _p/V _s structures derived from joint inversion and the relocated earthquakes can provide better constraints for analyzing the lateral heterogeneity and deep tectonic characters in the crust and upper mantle. Our tomographic results reveal significant relations between the seismic wavespeed structure and the tectonic characters. In the shallow depth, sedimentary basins and orogen show distinct wavespeed anomalies, with low V _p, high V _p/V _s in basins and high V _p, low V _p/V _s in orogen. As the suture zone of Eurasian Plate and Philippine Sea Plate, Longitudinal Valley is characterized by a significant high V _p/V _s anomaly extending to the middle-lower crust and upper mantle, which reflects the impact of rock cracking, partial melting, and the presence of fluids. In the northeast Taiwan, the V _p, V _p/V _s anomalies and relocated earthquakes depict the subducting Philippine Sea Plate under the Eurasian Plate. The high V _p of oceanic plate and the low V _p, high V _p/V _s atop the subducted oceanic plate extend to 80 km depth. Along the east-west profiles, the thickness of crust reaches 60 km at the east of Central Range with eastward dipping trend, which reveals the eastward subduction of the thickened and deformed crust of the Eurasian continental plate. Supported by Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX3-SW-234-2), National Basic Research Program of China (Grant No. 2007CB411701), National High Technology Research and Development Program of China (Grant No. 2006AA09A101-0201) and National Natural Science Foundation of China (Grant Nos. 40804016, 40704013)     

青海、新疆和西藏地区地震活动平静特征参数Wq值强震预测模式及其应用

以青海、新疆、西藏地区为研究区域,系统研究总结了该区域2010—2020年5.0级以上地震前W_q值的时空演化特征,并以2020年新疆于田6.4级和西藏尼玛6.6级地震为实例进行阐述。得出以下三点认识:①地震一般发生在W_q值异常扩展时段或扩展—减小时段,6.0级以上W_q值异常的震例中,约81%发生于异常出现后的9个月内;②地震一般位于W_q值异常面积扩展区或扩展—减小恢复区附近,近70%的震例发生在W_q值异常区内;③建立了震级与W_q值异常区面积间的正相关统计模型,二者的相关系数(R)为0.85,为预测青海、新疆和西藏地区地震的强度提供了定量关系。青海、新疆和西藏地区W_q值方法对6.0～6.9级地震的预测效果(W_q值异常的地震报准率为61%)优于5.0～5.9级地震(W_q值异常的地震报准率为26%),为我国地球物理观测程度较低地区开展强震中短期(1年内)预测提供了参考依据。     

Application of Fisher method to discriminating earthquakes and explosions using criterion m b/ M S

We try to give a quantitative and global discrimination function by studying m _b/M _S data using Fisher method that is a kind of pattern recognition methods. The reliability of the function is also analyzed. The results show that this criterion works well and has a global feature, which can be used as first-level filtering criterions in event identification. The quantitative and linear discrimination function makes it possible to identify events automatically and achieve the goal to react the events quickly and effectively. Contribution No.05FE3018, Institute of Geophysics, China Earthquake Administrtion.     

Instantaneous global ozone balance including observed nitrogen dioxide

The catalytic destruction of stratospheric ozone by the oxides of nitrogen is believed to be an important part of the global ozone balance. The lack of sufficient measurements of NO _x concentrations has impeded efforts to quantify this process. Recent measurements of stratospheric nitrogen dioxide from ground-based stations as well as aircraft and balloons have provided a first approximation to a global distribution of NO₂ vertical columns at sunset. These observed vertical columns have been translated into time-dependent vertical NO₂ profiles by means of a one-dimensional atmospheric photochemical model. Using recent observations of air temperature and ozone along with this information, the independent instantaneous (one second) rates of ozone production from oxygen photolysis P(O₃), of ozone destruction from pure oxygen species (Chapman reactions) L(O _x ), and of ozone destruction by nitrogen oxides L(NO _x ) were estimated over the three-dimensional atmosphere. These quantities are displayed as zonal average contour maps, summed over various latitude zones, summed over various altitude bands, and integrated globally between 15 and 45 km. Although the global summation between 15 and 45 km by no means tells the complete story, these numbers are of some interest, and the relative values are: P(O₃), 100; L(O _x ), 15; L(NO _x ), 45±15. It is to be emphasized that this relative NO _x contribution to the integrated ozone balance is not a measure of the sensitivity of ozone to possible perturbations of stratospheric NO _x ; recent model results must be examined for current estimates of this sensitivity.     

内蒙古地震台网近震震级与面波震级间转换关系研究

利用内蒙古及周边2008~2015年11月116次M_L≥3.8地震资料,重新测定近震震级M_L、面波震级M_S,基于1范数线性回归(SR1和SR2)和2范数正交回归(OR)方法建立M_L与M_S间的转换关系。同时,对每个点采用高斯随机扰动后发现,高斯扰动前后近震震级与面波震级间的转换关系变化不大。结果显示,正交回归方法(OR)得到的曲线,均方根误差最小,为最佳拟合曲线,转换关系式为M_(S,内蒙)=0.96M_L-0.10。郭履灿震级转换关系M_S=1.13M_L-1.08与本文得到的转换关系存在明显系统偏差,这可能是由于区域构造特征差异所致。M_(S,内蒙)值明显大于M_(S,经验)值,平均差值为0.23,建议使用重新矫正的M_L与M_S转换关系式,M_(S,经验)与M_(S,内蒙)差值数量分布情况显示,差值为0.2~0.3的地震数量最多。