共查询到20条相似文献，搜索用时 203 毫秒
1.
安徽地区震源参数特征研究 总被引：1，自引：0，他引：1
根据安徽数字测震台网记录的23个地震波形事件,首先采用Atkinson方法得到安徽地区的非弹性衰减特征,再用Moya方法得到24个台站的场地响应。在此基础上,扣除传播路径、场地响应和仪器响应的影响,利用遗传算法得到2009年以来安徽测震台网记录的42个ML≥2.0地震的震源参数,并对这些震源参数特征进行了系统的分析与研究。研究结果表明,安徽地区地震的地震矩与近震震级之间存在较好的线性关系,近震震级与矩震级存在一定的偏差,应力降与近震震级存在明显的正相关,震级越大,拐角频率越小,震源破裂半径越大。 相似文献
2.
3.
龙门山断裂带科学钻探3号井孔附近微震近震震级与矩震级的关系及意义 总被引：1，自引：0，他引：1
通过震源谱拟合得到龙门山断裂带科学钻探3号井孔附近218个微震的矩震级,并分别基于《地震台站监测规范》的量规函数(量规函数GF)和李学政等(2003)的量规函数(量规函数LXZ)计算了这些微震的两种近震震级。基于回归分析得到了两种近震震级与矩震级的关系,并讨论了此关系可能隐含的意义。近震震级与矩震级拟合关系M_W=a+bM_L中系数b的取值与应力降Δσ和地震矩M_0的关系相关,b=1/(1+γ)等价于Δσ∝M_0~γ,本文对应于γ=1的情形。由于动态应力降在数值上与静态应力降差别不大,这种关系同样适用于折合能量和视应力,因此仅根据拟合关系M_W=a+bM_L中b的大小就可以判断地震矩与应力降、折合能量及视应力的关系。基于量规函数LXZ得到的近震震级与能量震级更为接近,且两者在与矩震级的拟合关系M_W=a+bM_L中有相同的b,接近于0.5,这既印证了从b的大小来判断应力降与地震矩关系的论断,也说明从能量的角度来看量规函数LXZ优于量规函数GF。 相似文献
4.
5.
基于微震监测仪器频带及波形记录的时频特征,我们筛选出汶川地震科学钻探3号井孔周围微震台阵2012年记录的218个t_s-t_p1 s的微震.通过盖戈法与和达法相结合确定微震震源的几何参数,发现这些微震分布大体呈NE-SW展布,与龙门山断裂带的走向基本一致.无论是采用《地震台站观测规范》中的量规函数(量规函数GF)还是李学政等(2003)的量规函数(量规函数LXZ),近震震级均与矩震级呈现出较好的线性关系,向震级小的一端延伸时都表现为M_LM_W,但采用李学政等的量规函数时该趋势更加明显.同时采用Brune和Boatwright震源谱衰减模型对观测震源谱的拟合表明拐角频率具有模型依赖性:基于Brune模型拟合得到的拐角频率大于基于Boatwright模型得到的拐角频率.无论基于哪一种模型,矩震级与拐角频率、破裂半径的对数线性关系均较弱,与应力降、视应力的对数则存在较好的线性关系.这些关系不支持应力降、折合能量、视应力为常数的观点,表明微震与大地震的震源物理过程存在差异.视应力与应力降成比例,比例系数小于0.5,表明破裂动力学模式符合SavageWood模式.近震震级与矩震级拟合关系Mw=a+bM_L中b的大小与应力降和地震矩的关系有关,△σ∝M_0~γ,则b=1/(1+γ),因此从b的大小可以粗略地判断应力降与地震矩的关系.本文对应于γ≈1的情况,与基于量规函数LXZ得到的近震震级与矩震级关系中系数b=0.53吻合,这说明仅从辐射能量的角度考虑量规函数LXZ较量规函数GF准确. 相似文献
6.
7.
2008年盈江5.9级地震序列震源参数研究 总被引：6，自引：1，他引：5
2008年8月21日在云南省盈江县发生了MS5.9地震。利用云南区域数字地震台网记录的ML≥2.5余震波形记录,通过对S波观测记录谱进行传播路径、场地响应和仪器响应等影响的逐一消除,得到了196个ML≥2.5地震的震源谱,进而根据Brune圆盘震源模型,利用遗传算法计算了地震矩、应力降、震源半径等震源参数,结果表明,该地震序列的地震矩在1012～1016N.m间,与近震震级有很好的线性关系,与震源半径也呈线性关系;应力降与近震震级有一定的线性趋势相关性;拐角频率和地震矩之间有明显的依赖关系。 相似文献
8.
9.
2009年7月9日在云南省姚安县发生M6.0地震,利用云南区域数字地震台网记录的ML≥2.0余震波形记录,通过对S波观测记录谱进行传播路径、场地响应和仪器响应等影响的逐一消除,得到131个地震的震源谱.进而根据Brune圆盘震源模型,利用遗传算法计算地震矩、应力降、震源半径等震源参数.结果表明,该地震序列的M0在1012-1016N·m,与近震震级有很好的线性关系,与震源半径呈线性关系;应力降与近震震级有一定线性趋势相关性;拐角频率和地震矩M0之间有明显的依赖关系. 相似文献
10.
利用山东数字地震台网记录到的胶东半岛及附近地区2010年以来的地震波形资料,采用Brune模型,并结合遗传算法反演了本区134次2.0级以上地震的震源波谱参数.结果表明胶东半岛地区中小地震的地震矩在9.76×1011～5.9×1014N·M之间;应力降范围在0.017～25MPa之间,均值是0.97MPa;视应力范围在0.06～10.2MPa,平均应力水平在0.396MPa.地震矩、应力降和视应力都与震级呈正相关关系,拐角频率与震级的关系不是很明显;地震矩和拐角频率成负相关关系.根据本区震源参数和震级的定量统计关系,去除震级影响,通过应力降和视应力随时间的变化得到目前正处于应力的释放时期. 相似文献
11.
E. M. Scordilis 《Journal of Seismology》2006,10(2):225-236
The existence of several magnitude scales used by seismological centers all over the world and the compilation of earthquake catalogs by many authors have rendered globally valid relations connecting magnitude scales a necessity. This would allow the creation of a homogeneous global earthquake catalog, a useful tool for earthquake research. Of special interest is the definition of global relations converting different magnitude scales to the most reliable and useful scale of magnitude, the moment magnitude, M
W. In order to accomplish this, a very large sample of data from international seismological sources (ISC, NEIC, HRVD, etc.) has been collected and processed. The magnitude scales tested against M
W are the surface wave magnitude, M
S, the body wave magnitude, m
b, and the local magnitude, M
L. The moment magnitudes adopted have been taken from the CMT solutions of HRVD and USGS. The data set used in this study contains 20,407 earthquakes, which occurred all over the world during the time period 1.1.1976–31.5.2003, for which moment magnitudes are available. It is shown that well-defined relations hold between M
W and m
b and M
S and that these relations can be reliably used for compiling homogeneous, with respect to magnitude, earthquake catalogs. 相似文献
12.
Sarfraz Khan Muhammad Waseem Muhammad Asif Khan Waqas Ahmed 《Journal of Seismology》2018,22(4):841-861
A reliable and homogenized earthquake catalogue is essential for seismic hazard assessment in any area. This article describes the compilation and processing of an updated earthquake catalogue for Pakistan. The earthquake catalogue compiled in this study for the region (quadrangle bounded by the geographical limits 40–83° N and 20–40° E) includes 36,563 earthquake events, which are reported as 4.0–8.3 moment magnitude (MW) and span from 25 AD to 2016. Relationships are developed between the moment magnitude and body, and surface wave magnitude scales to unify the catalogue in terms of magnitude MW. The catalogue includes earthquakes from Pakistan and neighbouring countries to minimize the effects of geopolitical boundaries in seismic hazard assessment studies. Earthquakes reported by local and international agencies as well as individual catalogues are included. The proposed catalogue is further used to obtain magnitude of completeness after removal of dependent events by using four different algorithms. Finally, seismicity parameters of the seismic sources are reported, and recommendations are made for seismic hazard assessment studies in Pakistan. 相似文献
13.
In this paper, we give a brief introduction to the proposal and development history of the earthquake magnitude concept. Moment magnitude MW 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 MS. 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. 相似文献
14.
The 2018,Songyuan,Jilin M_S5. 7 earthquake occurred at the intersection of the FuyuZhaodong fault and the Second Songhua River fault. The moment magnitude of this earthquake is M_W5. 3,the centroid depth by the waveform fitting is 12 km,and it is a strike-slip type event. In this paper,with the seismic phase data provided by the China Earthquake Network, the double-difference location method is used to relocate the earthquake sequence,finally the relocation results of 60 earthquakes are obtained. The results show that the aftershock zone is about 4. 3km long and 3. 1km wide,which is distributed in the NE direction. The depth distribution of the seismic sequence is 9km-10 km. 1-2 days after the main shock,the aftershocks were scattered throughout the aftershock zone,and the largest aftershock occurred in the northeastern part of the aftershock zone. After 3-8 days,the aftershocks mainly occurred in the southwestern part of the aftershock zone. The profile distribution of the earthquake sequence shows that the fault plane dips to the southeast with the dip angle of about 75°. Combined with the regional tectonic setting,focal mechanism solution and intensity distribution,we conclude that the concealed fault of the Fuyu-Zhaodong fault is the seismogenic fault of the Songyuan M_S5. 7 earthquake. This paper also relocates the earthquake sequence of the previous magnitude 5. 0 earthquake in 2017. Combined with the results of the focal mechanism solution,we believe that the two earthquakes have the same seismogenic structure,and the earthquake sequence generally develops to the southwest. The historical seismic activity since 2009 shows that after the magnitude 5. 0 earthquake in 2017,the frequency and intensity of earthquakes in the earthquake zone are obviously enhanced,and attention should be paid to the development of seismic activity in the southwest direction of the earthquake zone. 相似文献
15.
Majid Nemati 《地震科学（英文版）》2019,32(2):80-97
Persian territory, which is dividable into major seismotectonic provinces, always suffers from damages of moderate and large earthquakes from ancient era to modern time. Therefore, temporal prediction of earthquake occurrence in this kind of area is an important topic. For this purpose, 628 moderate-large (5.5 ≤MS≤ 8.2) earthquakes occurred in Persia during the period from 400 B.C. to 2015 C.E. were used. Considering the magnitudes of events preceding main shocks and the annual seismic moment release in seismic source areas in the provinces, we calibrated equations predicting inter-event time of occurrence of moderate and large earthquakes (MW>5.5) in Iran. In each source area, inter-event times between moderate and large shocks with magnitudes equal to or larger than a certain cut-off magnitude (MW5.5) were calculated. The inter-event times between the earthquakes were used to compute the relationships using multiple regression technique. Calculated relationships express the basic idea of the time predictable model predicting the occurrence time of the future main shock in a certain seismogen area. However, despite of unavoidable scatter in observations and uncertainties in the results, occurrence times of main shocks during the next years and decades in some source areas in Iran were determined. 相似文献
16.
本文采用分层粘弹性介质模型计算了汶川地震对芦山震中产生的库仑应力加载的影响,进而结合Dieterich(1994)提出的速率状态摩擦定律给出芦山附近区域6级地震累积发震概率随时间的变化。结果显示,2013年芦山7.0级地震时其累积发震概率达18%,说明汶川地震产生的应力扰动加速了芦山地震的发生。本文还计算了汶川、芦山2次地震对其间"破裂空段"处产生的累积库仑应力扰动的影响,结合背景地震发生率,给出了"破裂空段"处6级地震累积发震概率变化。虽然计算结果可能受到大邑地震、介质模型参数的选取和背景地震发生概率等因素影响而存在一定误差,但"破裂空段"在2次强震应力加载下累积发震概率是不断增大的,因此我们认为"破裂空段"处发生中强地震的紧迫性不断增强。 相似文献
17.
Rupture model of the 2013 M_W 6.6 Lushan (China) earthquake constrained by a new GPS data set and its effects on potential seismic hazard 
下载免费PDF全文
下载免费PDF全文 Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10~(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes. 相似文献
18.
2022年1月8日青海省海北州门源县发生MS6.9地震,震中距离2016年1月21日门源MS6.4地震震中约33km,两次门源地震均发生在冷龙岭断裂附近,但在震源机制、主发震断层破裂过程及地震序列余震活动等方面显著不同。针对两次门源地震序列的比较分析,对研究冷龙岭断裂及其附近区域强震序列和余震衰减特征等具有重要研究意义。通过对比分析2022年门源MS6.9地震和2016年门源MS6.4地震余震的时空演化特征,发现二者在震源过程和断层破裂尺度上存在明显差异,前者发震断层破裂充分,震后能量释放充分,余震丰富且震级偏高;而后者发震断层未破裂至地表,余震震级水平偏低。综合分析两次门源地震序列表现出来的差异性,认为其可能与地震发震断层的破裂过程密切相关,且同时受到区域构造环境的影响。 相似文献
19.
Source parameters of the earthquakes of the Baikal rift system 总被引：1，自引：0，他引：1
A. A. Dobrynina 《Izvestiya Physics of the Solid Earth》2009,45(12):1093-1109
The dynamic parameters of the earthquake source—the seismic moment, the moment magnitude, the source radius, the stress drop,
and the amplitude of displacement—are determined by the amplitude Fourier spectra of the body shear waves (S-waves) for 62 earthquakes of the Baikal rift system with the energy class of K
P
= 9.1–15.7. In the calculations I used the classical Brune model. The seismic moment of the earthquakes being investigated
changes from 3.65 × 1011 N m to 1.35 × 1018 N m, and the radii of earthquake sources vary from 390 m to 1.84 km. The values of the drop in stress Δσ grow with an increase
in the seismic moment up to 1.7 × 108 Pa. For the group of weak earthquakes (M
w
= 1.7–3.3), extremely low values of the drop in stress 103–104 Pa are observed. The maximum amplitude of displacement in the source amounts to 5.95 m. The empirical equations between the
seismic moment and the other dynamic parameters of the source are determined. The regional dependence of the seismic moment
and energy class is obtained: log M
0 ± 0.60 = 1.03K
P
+ 3.17. The character of the relationship between the seismic moment and the corner frequency indicates that the classical
scaling law of the seismic spectrum for the earthquakes in question is not fulfilled. The obtained estimates of the dynamic
parameters are in satisfactory agreement with the published data concerning the analogous parameters of the other rift zones,
which reflects the general regular patterns of the destruction of the lithosphere and the seismicity in the extension zones
of the lithosphere. 相似文献
20.
海域地震对我国海洋资源开发和沿海地区的经济建设形成严重威胁,开展相关地震活动性研究的重要前提是编译我国海域及邻区的地震目录。我国常用的震级标度为面波震级(MS),而国际上最新的地震活动模型多采用矩震级(MW),因此在应用这些模型时需要拟合面波震级与矩震级之间的转换关系。本文以中国海域及邻区为研究区,收集了1988—2020年中国地震台网的面波震级和全球矩心矩张量(GCMT)项目的矩震级数据,从中提取年份、深度、经度、纬度、面波震级作为影响因子,以实际记录的矩震级值作为标记,训练BP神经网络建立以GCMT的矩震级为目标的震级转换模型。同时,使用最小二乘回归和正交回归建立线性模型作为对比。结果显示,最小二乘回归和正交回归的平均绝对误差和均方根误差比BP神经网络高40%左右。此外,BP神经网络的残差绝对值更小、分布更集中。 相似文献