共查询到20条相似文献，搜索用时 15 毫秒
1.
利用2014年1月-2015年12月浙江省区域数字地震台网记录的1 360次珊溪水库ML0.5-4.4地震资料,采用Brune模式,将台站获取的速度记录进行几何扩散校正、介质衰减校正及仪器校正后得到速度谱,对速度谱在频率域进行傅里叶积分得到震源位移谱,之后使用遗传算法计算得到拐角频率和震源位移谱零频极限值,进而计算出该区的地震矩为1010-1014 N·m,震源破裂半径为33-550 m,拐角频率为2.4-39.7 Hz,地震应力降为0.04-6.74 MPa,视应力为0-2.75 MPa.在此基础上,对各参数特征及其关系进行系统性分析,结果表明:各震源参数之间表现出一定的对数线性或半对数线性关系;空间上,应力降和拐角频率在库区西北段较高,东南段较低;应力降与地震矩在空间上呈反向关系,拐角频率与破裂半径在空间上呈负相关. 相似文献
2.
使用广西数字地震台网记录的2013年6月-7月广西平果ML1.0-3.0震群162次地震波形资料,采用Brune（1970）模型,通过几何扩散校正、介质衰减校正、仪器校正等,将速度记录谱归算为震源位移谱,利用遗传算法计算拐角频率及零频极限,然后计算地震矩、应力降等小震震源参数,系统分析各参数之间的关系.研究表明：近震震级、地震矩、震源破裂半径、拐角频率、应力降等之间可以拟合为对数或半对数的线性关系;地震应力降、视应力与震源破裂半径没有明显的依赖关系,但与地震矩成正相关关系;与其他地区的同类研究结果基本一致,获得各参数的定标关系相近,尤其是通过最小二乘法拟合应力降与地震矩之间的关系后,与浙江珊溪水库地区的应力降与地震矩之间的关系有很强的一致性;与其他地区的应力降及视应力降相比较,本研究区属于低应力释放地区,但由于此次研究的地震事件时间跨度较短,且时间段比较集中,对该地区的应力释放水平还需跟踪研究. 相似文献
3.
利用广西南丹县大厂矿区地震监测台网记录的地震波资料,采用Brune（1970）模型,将速度记录谱归算为震源位移谱,使用遗传算法计算拐角频率及零频极限,然后计算地震矩、应力降等小震震源参数,并系统分析各种参数之间的关系。大厂矿区38次较大地震的震源参数计算结果为：地震矩范围在2.18×1011~7.89×1012 N·m之间;震源破裂半径78~439m;地震应力降在0.01~1.79 MPa之间。表明：地震矩与震级、震源半径、拐角频率之间呈线性关系,而应力降不依赖于地震矩,分布较为离散。大厂矿区应力降值明显偏低,这可能与该区域背景应力低有关。 相似文献
4.
Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetry Seismic Network in the Capital Circle Region of China and its surrounding areas from January 2002 to June 2006 by the Brune model.Relevant formulas that were used for the calculation of dynamic source parameters include rupture radius,seismic moment,seismic energy,stress drop,and apparent stress.Scaling relations and characteristics of temporal-spatial variations of these dynamic parameters before the MS5.1 Wenan earthquake in Hebei Province that occurred on July 20,2006 were analyzed.Results show that apparent stress,stress drop,and the ratio of seismic energy to the rupture radius had relatively high values in some areas before the Wenan earthquake.These high-value concentration areas were mainly distributed in the North China Plain seismic zone.As is seen from the time curves,parameters,such as apparent stress,stress drop,and ratio of seismic energy to rupture radius underwent significant ascending processes before the Wenan earthquake,but the variation in the corner frequency showed a descending trend.This result might be related to the enhancement of stress in the North China Plain seismic zone before the earthquake. 相似文献
5.
通过对甘肃数字地震台网2008年1月-2009年6月记录的ML 2.0-ML 6.0中小地震,S波观测谱中噪音、仪器、路径、场地等影响的逐一消除,利用遗传算法反演得到甘肃地区273条地震的震源谱,进而根据Brune的圆盘震源模型,计算地震矩、应力降、拐角频率、震源半径等震源参数,并研究甘肃地区震源参数的特征及相似关系.... 相似文献
6.
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
7.
The data analysis of the source parameters of five sets of earthquake sequences, aftershocks and earthquakes scattered in
a region shows that the scalar seismic moment is correlated with the linear size of the fault and the static stress drop.
We tentatively imply that a correlation also exists between the radius of the faults and the static stress drops and it is
suggested that the static stress drop may be decreasing with increasing radius of the source. It is shown that the density
distribution of the source radius, calculated through the source rupture duration obtained from the body wave pulse (Boatwright,
1980) using the time T between the P-wave onset and the first zero crossing on the seismogram, may be represented by a power law as the density
distribution of the stress drops and of the moment which are also computed. It is also suggested, and tentatively verified,
that the density distribution of the areas of the broken barriers on the faults is similar to that of the density distribution
of the static stress drops. It is finally suggested that the seismicity of a region may be studied two-dimensionally as a
function of the stress drop and the radius of the source instead of the classic b and b0 values. Concerning the discussion on the range of the values of the static stress drop, whether it is almost constant in
a seismic region and varies only from one region to another, it is seen that in the aftershocks of the 1994 Northridge earthquake
it covers a range of almost 5 orders of magnitudes. Finally it is ascertained that the density distribution of the source
parameters does not give equipartition of seismic moment release. 相似文献
8.
利用“十五”数字化后山西地震台网记录的612次 ML ≥2．0地震,使用中国地震局地震预测研究所推广的中小地震新参数计算软件,计算其中148次事件的震源新参数,对地震矩、矩震级、震源破裂尺度、应力降、拐角频率等参数间的定标关系做初步研究,得出 ML 震级与地震矩、矩震级间存在较好的线性正相关;震级与震源尺度间存在多项式关系;与应力降的对数呈显著正相关,当大于 ML 4．0后,随着震级的增大,释放的应力降略有变缓;与拐角频率的对数呈负相关。 相似文献
9.
利用遗传算法,搜索符合Brune ω^2模型的拐角频率（fc）及零频幅值（Ωc）的最佳值,测定浙江珊溪水库震区88条小震（1．5≤ML≤4．6）的地震矩（M0）、震源尺度（r）及静态应力降（△σ）。地震矩M0在10^10～10^14N·m范围内,与拐角频率fc遵循Mo∝fc^-3的规律;震源尺度和地震矩、应力降之间呈现多重标度特征,地震矩大于临界值2．3×10^12N·m（相应的震源尺度特征值约160m）时,震源尺度与地震矩的关系较强;而应力降（△σ）在震源尺度大于160m后基本趋向恒定,不随震源尺度的增大而增大。浙江珊溪水库震区自2002年7月以来,经历2次大规模的震群活动。震群释放的应力降大小与该震群的规模成正比关系,大的应力降集中在发震断层中段5～6km深度的区域,其发生时间既可以在主震之前,也可以在主震之后。 相似文献
10.
应用2011年1月-2015年4月柯坪块体及周边数字地震台站（38°-42.5°N,75°-80.5°E）记录的3.0 ≤ M ≤ 5.0地震事件,结合柯坪块体介质品质因子和各台站场地响应,计算各地震应力降、地震矩、震源破裂半径、拐角频率等新震源参数,并研究各背景值变化特征及彼此间对应关系。结果表明：柯坪块体地区地震震级与地震矩、矩震级、震源尺度之间表现为较好的正相关性,与地震拐角频率之间呈负相关。地震矩与震源破裂尺度整体呈正相关,但当震源破裂尺度较小时,地震矩变化不大,当震源破裂尺度大于250 m时,地震矩随震源破裂尺度的增大变化较快。由柯坪块体应力降时间分布特征分析可知,研究区具有地震前应力降呈现高值异常、震后缓慢恢复低值的演化过程。 相似文献
11.
基于遗传算法,采用Atkinson方法,选取2009-2017年内蒙古数字地震台网记录的内蒙古西部地区ML ≥ 2.7地震事件波形资料,反演得到83个地震的震源参数。分析结果表明：该地区的拐角频率、地震矩、零频振幅与震级之间的相关性较好,而地震矩与应力降以及应力降与震级之间呈弱相关性,地震矩与拐角频率呈良好负相关性。其中,应力降集中分布在0.7-20 MPa,当ML > 3.6时,随着震级增大,应力降呈现较为离散的特征。 相似文献
12.
IntroductionTheseismoIogymethodofearthquakepredictionissometimessimplycalled"predictingearthquakebyearthquake",thatis,animpendinglargeearthquakeispredictedonbasisofsomefeaturesofsmaIlearthquakesoccurredbeforeit.Forthispurpose,thecharactersoftemporaryspatiaIandmagnitudedistributionofsmalIearthquakesareintensiveIyinvestigated,whichareusuallycalIedasseismicitymethod.ThesuccessfuIpredictionofHaichengearthquakeinl975wasitSremarkabIeappIication.Besides,thepossibIechangesincharactersofseismicsou… 相似文献
13.
利用山东台网记录的长岛震群2017年2月14日—9月1日期间的波形与震相资料研究长岛地区非弹性衰减系数,得到该地区介质平均Q值与频率f的关系式为Q(f)=363.9f1.374 1。采用Moya等[1]提出的利用遗传算法联合反演得到长岛周边台站的场地响应,根据Brune模型震源参数计算公式求解长岛震群序列地震震源参数。结果显示,各个震源参数之间均存在一定的相关关系,地震矩随ML震级的增大而增加,地震矩与破裂半径R之间存在半对数关系,拐角频率fc随地震矩的增大而减少;长岛地震序列的应力降数值普遍偏小,最大不超过0.9MPa,这意味着长岛震源区整体构造应力较低,也可能指示长岛震群为低摩擦应力的断层作用;震源参数随时间的变化方面,整体而言,长岛震群地震应力降变化起伏很大,在M4.1地震发生前,拐角频率与应力降均发生快速下降后随即翻转上升的现象,证明在M4.1地震发生前震源区整体应力的挤压逐渐增强。 相似文献
14.
15.
基于安徽数字地震台网2010年1月至2017年12月记录到的ML2.5~5.0级地震,根据中小地震震源参数测定原理,利用多台多地震联合反演Atkinson方法和Moya方法分别计算了安徽地区地壳平均非弹性衰减因子Q值和安徽24个省属专业地震的台站场地。在此基础上,运用遗传算法求得安徽地区96个地震事件的震源谱参数,进而根据Brune中小地震圆盘模型计算其拐角频率、地震矩、应力降、矩震级、震源尺度等震源参数,并分析其特征及相互之间的关系。研究结果表明:安徽地区中小地震的ML震级与其他震源参数之间存在一定相关关系,而地震矩M0与应力降Δσ、震源尺度r和拐角频率fc之间并未表现出明显的相关关系。 相似文献
16.
S. J. Gibowicz 《Pure and Applied Geophysics》1998,153(1):5-20
—The values of uniformly estimated apparent stress σa and Brune’s stress drop, taken as a measure of static stress drop, from 850 seismic events, with moment magnitude ranging from ?3.6 to 3.6, induced at the Underground Research Laboratory (URL) in Canada, Western Deep Levels (WDL) gold mine in South Africa, and two coal and two copper mines in Poland, were collected to study the stress release mode in various mining environments. For this, the quantity epsilon, ?=Δσ/(σa + Δσ/2), where Δσ is the static stress drop, proposed by Zúñiga (1993) as an indicator of stress-drop mechanism was used. The events induced at the URL are characterized by low values of epsilon corresponding to a partial stress drop mechanism, whereas all the events at WDL display a frictional overshoot mechanism in which final stress reaches a lower value than that of frictional stress. The events at Polish coal and copper mines, on the other hand, are in good agreement with the well-known Orowan’s condition such that the final stress is equal to the dynamic frictional stress.¶The Brune stress drop, however, is heavily model dependent through the source radius-corner frequency relation. The Orowan’s condition for the events from the URL would be met if a constant in the source radius-corner frequency relation is equal to 1.82 ± 0.12, and for the events from WDL if it is equal to 3.92 ± 0.40, in contrast to Brune’s constant of 2.34.¶The smoothed values of epsilon displayed as a function of time, represented by the consecutive event numbers, for selected sets of events imply that the largest seismic events in a given set occur when the epsilon is low and a partial stress drop mechanism is dominant. The large events are then followed by high epsilon values when a frictional overshoot mechanism begins to dominate. 相似文献
17.
本文利用紫坪铺水库台网记录到的波形资料,计算了2004～2008年170个ML≥1.0级地震的震源参数.紫坪铺水库震源参数计算结果与其他大陆地区有明显不同:(1)拐角频率远低于其他大陆地区结果,表明库区地震波传播经过了较强的衰减过程;(2)视应力计算结果比其他地区小3个数量级,可能是由于库区地震波的高频成分衰减强烈,低估了能量集中在高频的小地震的地震辐射能量.分析了蓄水前后拐角频率和地震矩以及视应力和地震矩关系(视应力标度率)变化,结果表明:相同地震矩的地震蓄水后拐角频率增加,地震高频成分相对丰富;蓄水前视应力与地震矩的关系不明显,蓄水后视应力随地震矩的增加而增加.视应力标度率的改变可能是蓄水后地震震源物理过程逐渐改变的直接反映. 相似文献
18.
利用成都遥测数字地震台网数字地震波形数据资料,采用Atkinson方法得到四川地区的品质因子Q值与频率,的关系为：Q（f）=203．1f0.834。采用Moya方法反演得到了地震的场地响应,采用Moya方法与Atldnson方法分别得到了相应地震的震源谱参数,两种方法的结果保持了很好的一致性。得到的震源参数结果表明：地震矩与震级的关系为：logM0=17．27＋1．18Mt,地震矩与拐角频率关系,即随着地震矩的增大,拐角频率减小,这些地震的应力降在10-400巴之间,应力降与地震矩之间没有明显的依赖关系。 相似文献
19.
Raul Madariaga 《Pure and Applied Geophysics》1977,115(1-2):301-316
We discuss the inversion of stress drops from seismic observations on the basis of crack or stress-drop models of earthquake mechanism. Since a formal inverse problem cannot be posed at present we discuss implications of solutions to direct problems. We first discuss the static approximations used to obtain stress drop from seismic moment and source dimensions. We show that the geometrical effects are quite significant if only one source dimension has been retrieved from seismic observations. The effect of variable stress drop is discussed and we show that the inverted stress drop is not a simple average of the actual stress drops on the fault. We discuss the energy release during faulting and show that the apparent stress has a complicated relation to the stress drop on the fault. We also show that the static stress drops obtained by seismologists are a lower bound to the actual dynamic stress drops on the fault. This may in part explain disagreements with laboratory results. Finally, we discuss the inversion of source dimensions from the far-field radiation. We analyse two extreme, simple dynamical source models, a circular fault and a rectangular fault and show that geometry has a much more pronounced effect on radiation than is usually acknowledged. 相似文献
20.
Introduction Seismic recording is the information recorded by seismograph when earthquake occurs, which is a kind of comprehensive information, including the characteristics of earthquake focus, propagation path of seismic wave and site response, etc. Therefore, we must try to distinguish source effect, propagation path and site response in the seismic recordings in order to obtain accu-rate parameters. The method of Atkinson has better solved the problem (Atkinson, Mereu, 1992), which is bas… 相似文献