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1.
分析G-R-闵公式后得出,它是从点源幅射场导出的,与地震宏观场不相应。因在近场震源不能视作点源。在分析过程中,导出相当于点源、线源或面源以及复杂源的幅射场的深度公式。对实际的地震,它的源类型一无所知,所以不预作假定,将源指标几何扩散率n作为待定参数,导出了一个物理意义明确而又普遍化的震源深度公式。此公式的诸解法中,以计算方法准确、精度高,作图法有直观的优点,但准确性差、精度低,图算法只作获取粗略值和考察数据均匀性用。计算了9个8级以上巨震、1个71/2大震,和两个M_L=3的有感地震的震源深度,经对比结果很好,利用计算得出震源类型,结合宏观场研究了这些地震的震源几何学。并且首次在国际上给出宏观地震震源深度值的标准误差。 相似文献
2.
基于对在近场吸收系数A/km~2和源指标几何扩散率n都因实际地震而异的认识,导出了完整宏观地震震源深度公式,获得确定震源深度考虑吸收的宏观地震方法的通解。对此通解及宏观地震震源深度公式各提出三种算法以满足三种需要,经过三个实例,两公式六种算法对比计算结果都很好,并利用所得震源类型结合宏观场探索了震源几何学,为钻探地震直接观察震源的钻孔设计提供依据。 相似文献
3.
宏观地震方法考虑吸收确定震源深度问题的通解 总被引：1，自引：1，他引：0
每个地震都有震源,而震源类型则各式各样,震源幅射能量到地面所产生的宏观场也各不相同,因此在近场,描述宏观场物徵的两个参数：源指标几何扩散率ｎ和吸收系数Ａ／ｋｍ＾２也因地震而异,它们的量值完全由实际的宏观场确定。由此导出完整宏观地震震源公式获得宏观地震方法考虑吸收确定震源深度问题的通解,对比能解和宏观地震震源深度公式各提出三种计算方法,以满足三种不同的需要,经过四个实例两公式的几种算法相互对比,结果 相似文献
4.
运用Pn震相对齐的方法分析了发生在中国台湾地区地震的sPn震相,总结了该地区地震sPn震相的一些特征,用sPn震相计算了震源深度并与单纯型定位法结果进行了对比。结果表明,在该地区地震中,sPn震相特征明显;应用该方法可以较准确地测定台湾浅源地震的震源深度。 相似文献
5.
根据震源指标几何扩散率ｎ和近场吸收系数ａ／ｋｍ＾２都随实际地震而异的性质，导出了完整震源深度公式，并获得Ｋ－Ｇ问题的通解。对此通解及震源深度公式分别提出３种算法，效果都较好，利用计算所得震源类型，结合宏观场粗略地探索了震源几何学，为直接观察震源的钻孔设计提供了依据。 相似文献
6.
根据震源指标几何扩散率ｎ和近场吸收系数α／ｋｍ２都随实际地震而异的性质，导出了完整震源深度公式，并获得Ｋ－Ｇ问题的通解。对此通解及震源深度公式分别提出３种算法，效果都较好。利用计算所得震源类型，结合宏观场粗略地探索了震源几何学，为直接观察震源的钻孔设计提供了依据 相似文献
7.
用单纯形法计算了阿克陶M_S6.7主震的震源深度,结果为7.5 km,但单纯形法对设定的初始深度依赖值过高,震源深度值不一定可靠。用PTD法计算了阿克陶M_S6.7主震的震源深度,结果为9.4 km,且用了44个台站的震相数据共组成99个有效样本数参与了计算,不仅样本数多,而且震源深度样本数的集中度也比较符合高斯分布的特征,所以震源深度值可信度高,也非常接近国内和国外地震研究机构给出的此次地震的震源深度。当主震的震源深度已知且适合单纯形法设定的初值时,用单纯形法来计算地震序列的震源深度,不仅残差小,而且软件实现简单,确保了地震序列的按时提交。再用PTD法来检验该地震序列震源深度的准确性,结果显示,2种方法得到的震源深度差值不超过10 km,符合中国地震台网对震源深度误差的要求。 相似文献
8.
利用宏观地震震源深度公式和完整宏观地震震源深度公式，计算了中国地震目录等书刊上的宏观地震场(等震线图)资料，得出震级为8.6～3.0的200次地震的震源深度，研究了它们的地理分布，可见中国地震以浅源地震为多．震源深度＜9 km者在200次中有162次(81.0%)．其中深度＜5 km者有111次(55.5%)，此种浅震多分布在南北地震带邻近各省，少数散布在除浙江省以外的各省．深度在10～20 km的中深地震较少，仅32次(15%)，多半分布在南北地震带及新疆西部、陕西、山西和山东(沿郯庐断裂带并过海至东北)．深度超过20 km的深源地震很少，散见于云南南部及内蒙东端． 相似文献
9.
宏观地震震源深度公式及其精确计算方法 总被引：2，自引：0，他引：2
在I1＝I0、r1＝r0时证明了h＝r0,即极震区成为震中区时震源深度恒等于震中区等震线半径．它是震源深度的理论标准,并由此演译出宏观地震震源深度公式的精确计算方法．对比计算表明,完整宏观地震震源深度公式及其常规计算方法是最佳选择． 相似文献
10.
1.引言 本文把估计地震所释放能量的方法分成静力学估计和动力学估计两类。前者用地震矩和应力降估计能量,后者从地震图中估计能量。在一些简单假设下,作者用公式:E=(5×10~(-5))M_0讨论了静力学能量。 用动力学估计地震体波能量的方法一般有两种:一是对某一确定台站记录到的地震波直接积分;一是对导出位移的震源一时间函数积分。著名的古登堡—里希特能量一震级关系式就是用第一种方法求得的。本文述及的是第二种方法计算的几个浅震和中深源地震的能量,采用这种方法时要先求出地震矩和震源一时间函数关系。 相似文献
11.
The macroseismic field of the Balkan area 总被引：1，自引：0，他引：1
A catalogue of 356 macroseimic maps which are available for the Balkan area was compiled, including information on the source parameters of the corresponding earthquakes, the macroseismic parameters of their strength and their macroseismic field. The data analysis of this catalogue yields new empirical relations for attenuation, which can be applied for the calibration of historical events, modelling of isoseismals and seismic hazard assessment. An appropriate analysis allowed the separation and estimation of the average values of the geometrical spreading, n, and anelastic attenuation factor, c, for the examined area which were found equal to –3.227 ± 0.112 and –0.0033 ± 0.0010. Scaling relations for the focal macroseismic intensity, If, and the epicentral intensity I0, versus the earthquake moment magnitude were also determined for each Balkan country. A gradual decrease of the order of 0.5 to 1 intensity unit is demonstrated for recent (after 1970) earthquakes in Greece. Finally the depths of the examined earthquakes as they robustly determined (error <5 km) on the basis of macroseismic data were found to have small values ( 10 km). However large magnitude earthquakes show higher focal depths ( 25 km), in accordance with an increase of the seismic fault dimensions for such events. 相似文献
12.
D. Benouar 《地震工程与结构动力学》1994,23(7):717-727
This paper presents the results of an investigation of the magnitude–intensity and intensity–attenuation relationships for earthquakes in the Atlas block and Algeria using macroseismic data. This work is based on a selected sample of isoseismal maps from 32 events which were recently revised. Surface-wave magnitudes, Ms, are recalculated using the Prague formula and range from 4·2 to 7·45. Because the Atlas mountains block is in a collision zone, earthquakes occur in general within a layer 15 km deep. Expressions of general form for the magnitude–intensity and intensity–attenuation correlations are adopted and are, respectively, and where R2 = d2 + h2, d the source distance in km, h the focal depth in km, Ms the revised surface-wave magnitude, Msc the predicted surface-wave magnitude, Ii the intensity at isoseismal i, I the predicted intensity, σ the standard deviation and P is zero for 50-percentile values and one for 84-percentile, and the coefficients A's and B's are determined by regression analysis. The results of this study show that the intensity–attenuation models are adequate to predict quite well the die-out of intensity with distance in the Atlas zone and coastal Algeria; it is also found that magnitude can be predicted accurately by calibrating isoseismal radii against revised instrumental surface-wave magnitude. Such magnitude–intensity relationships may be used to evaluate the magnitude of historical earthquakes in the region under survey, with no instrumental data, for which isoseismal radii and intensities are available. 相似文献
13.
The 2003 Ml = 5.4 Rambervillers earthquake, north-east of France, is the largest seismic event recorded north of the Alps
since the 1992 Ms = 5.3, I0 = VII, Roermond earthquake, Netherlands. With a maximum macroseismic intensity of VI-VII EMS-98, the 2003 event was broadly
felt to a distance of 300 km from the epicentre. It provides a unique opportunity to test and compare the different procedures
used in France, Germany and Switzerland when evaluating macroseismic intensities. The main purpose of this paper is to present
a common transfrontier macroseismic map based on the EMS-98 intensity scale. Maximum horizontal accelerations recorded in
the area are compared to the intensity values, and we propose to use a differential technique to re-estimate the magnitude
of the 1682 Remiremont, I0 = VIII, earthquake, which occurred 40 km south of Rambervillers. 相似文献
14.
Constantinos B. Papazachos 《Pure and Applied Geophysics》1992,138(3):445-469
A method is suggested for the analysis of macroseismic intensity data in order to accurately determine an average attenuation structure of the upper part of the crust in an area. The method is based on a model which assumes that the observed intensities depend on source properties (radiation pattern, size, focal depth), geometrical spreading and anelastic attenuation. The method is applied to 13,008 intensity values, observed in corresponding sites of Greece and grouped (in 4228 groups), according to their spatial clustering in order to diminish observational errors and site effects. An average intensity attenuation coefficient,c=–0.0039±0.0016, corresponding to a quality factor, Q=350±140, is determined for the upper 20 km of the crust in this area. This value is relatively low, in good agreement with the relatively high heat flow and high seismic activity of this area. A byproduct of the present study is the determination, for each earthquake, of a macroseismic focal depth and of a macroseismic size, which is strongly correlatted with both the earthquake's magnitude and its seismic moment determined by independent methods. 相似文献
15.
Gottfried Grünthal Dietrich Stromeyer Kurt Wylegalla Rainer Kind Rutger Wahlström Xiaohui Yuan Günter Bock 《Journal of Seismology》2008,12(3):413-429
The area south and east of the Baltic Sea has very minor seismic activity. However, occasional events occur as illustrated
by four events in recent years, which are analysed in this study: near Wittenburg, Germany, on May 19, 2000, M
w = 3.1, near Rostock, Germany, on July 21, 2001, M
w = 3.4 and in the Kaliningrad area, Russia, two events on September 21, 2004 with M
w = 4.6 and 4.7. Locations, magnitudes (M
L and M
w) and focal mechanisms were determined for the two events in Germany. Synthetic modeling resulted in a well-confined focal
depth for the Kaliningrad events. The inversion of macroseismic observations provided simultaneous solutions of the location,
focal depth and epicentral intensity. The maximum horizontal compressive stress orientations obtained from focal mechanism
solutions, approximately N–S for the two German events and NNW–SSE for the Kaliningrad events, show a good agreement with
the regionally oriented crustal stress field. 相似文献
16.
A disastrous earthquake with a magnitude M
S
= 8.0 (M
W
= 7.9), in China called “the 5.12 Wenchuan earthquake,” occurred on May 12, 2008, in Sichuan province on the border between
the Sino-Tibetan Mountains and the Sichuan depression. The instrumental epicenter was registered in the southeastern part
of Wenchuan county, and the hypocenter depth was 14 km. As the strongest and most destructive earthquake within mainland China,
it caused numerous human losses and destruction of buildings and infrastructure. The seismic effect from the main shock and
aftershocks was felt in many counties, towns, and villages, though Sichuan province suffered the most. The maximum intensity
of the shocks was estimated at 11 degrees, according to the Chinese macroseismic scale. In the process of source opening,
from the southern part of Wenchuan county to the vicinities of Quingchuan, a seismic fault system with a total length up to
240 km out-cropped on the earth’s surface, confined to the Longmenshan fault belt. The seismic fault system disturbed the
original ground, resulting in the collapse or damage to various constructions, such as buildings, homes, bridges, roads, etc.
Fault offsets had a dextral strike-slip and thrust kinematic combination. The earthquake generated several tens of thousands
of landslides, rockfalls, and debris flows. Many dammed ponds appeared in the epicentral zone due to the activation of landslides.
Thus, the geological effects turned out to be the most destructive factor in this case. At the same time, the seismic intensity
of surface shaking was abnormally low even in direct proximity to the seismic fault system. Usually it was no more than 7–8
degrees. This macroseismic phenomenon may turn out to be rather typical for many major earthquakes. 相似文献
17.
Ground motion prediction equations (GMPE) in terms of macroseismic intensity are a prerequisite for intensity-based shake
maps and seismic hazard assessment and have the advantage of direct relation to earthquake damage and good data availability
also for historical events. In this study, we derive GMPE for macroseismic intensity for the Campania region in southern Italy.
This region is highly exposed to the seismic hazard related to the high seismicity with moderate- to large-magnitude earthquakes
in the Appenninic belt. The relations are based on physical considerations and are easy to implement for the user. The uncertainties
in earthquake source parameters are accounted for through a Monte Carlo approach and results are compared to those obtained
through a standard regression scheme. One relation takes into account the finite dimensions of the fault plane and describes
the site intensity as a function of Joyner–Boore distance. Additionally, a relation describing the intensity as a function
of epicentral distance is derived for implementation in cases where the dimensions of the fault plane are unknown. The relations
are based on an extensive dataset of macroseismic intensities for large earthquakes in the Campania region and are valid in
the magnitude range M
w = 6.3–7.0 for shallow crustal earthquakes. Results indicate that the uncertainties in earthquake source parameters are negligible
in comparison to the spread in the intensity data. The GMPE provide a good overall fit to historical earthquakes in the region
and can provide the intensities for a future earthquake within 1 intensity unit. 相似文献
18.
Excavations in the former Roman provincial capital of Pannonia Superior, Carnuntum, 40 km east of Vienna revealed damaged masonry structures from many parts of the ancient settlements. A compilation of structurally damaged buildings has formerly been given by Kandler (Acta Archaeol Acad Sci Hung, 41:313–336, 1989), who related damage to an earthquake in the middle of the fourth century a.d. This paper reviews and supplements these data, and discusses the significance of the style of damage. It is concluded that seismic damage is the only likely interpretation for the damaging mechanism. Although archaeological age dating for the individual collapsed buildings only constrains the timing of their destruction to a few decades around 350 a.d., we assume a single damaging event. In spite of the restrictions on damage assessment by the nature of the archaeological data, it is possible to give a reasonable appraisal of macroseismic intensity. The tentative seismological interpretation of damage leads to an intensity estimate of about nine of the European macroseismic scale (EMS-1998). Comparison with macroseismic data of modern earthquakes in the region, which show a rapid decrease of intensity with distance form the epicentre, indicate a near-by seismic source unless exceptionally high epicentral intensities are assumed for the fourth century event. The most likely source is an active sinistral strike-slip fault (Lassee Fault) passing about 8 km NW of the archaeological site. The fault belongs to Vienna Basin fault system with about 2 mm sinistral movement per year. The system is characterized by fault segmentation and distinct seismicity along the different segments. Moderate seismicity during the last centuries at the southern segments (e.g., Schwadorf 1927, I
0=8) strongly contrasts from the Lassee fault segment with Carnuntum as the only known severe earthquake. The earthquake of Carnuntum provides evidence for the overall seismic style of deformation along this segment, which previously has not been regarded seismically active. Also, the fourth century earthquake is the strongest event known from the Vienna Basin fault so far. 相似文献
19.
V. I. Ulomov 《Izvestiya Physics of the Solid Earth》2010,46(1):1-18
According to the normative maps of the General Seismic Zoning in the Russian Federation, OSR-97, the Moscow metropolitan area
is situated within the 5 point seismic zone. Of highest hazard priority for tall buildings in Moscow are the low-frequency
vibrations proceeding from the deep sources of strong earthquakes that occur in the East Carpathians (the Vrancea zone, Romania)
at a distance of approximately 1350 km from Moscow. Accelerations of the ground vibrations in Moscow are found from the analysis
of seismic signals produced by Mw = 5.0 to Mw = 7.4 Vrancea earthquakes and recorded at the Moskva seismic station. Extrapolation of the parameters of the weak and moderate
earthquakes towards stronger seismic events provides an estimate for the maximum expected horizontal accelerations of Ahor = 2.3 cm/s2 in case of the Mw = 8.0 Vrancea earthquake. The synthetic accelerogram of the maximum possible effect on the benchmark soils of Moscow is calculated.
The displacements of the ground are multidimensional and not necessarily oriented strictly towards the seismic source. These
inferences suggest that the MSK-64 macroseismic scale be corrected and the Construction Norms and Regulations, SNIP II-7-81*,
be updated with regard to the hazard assessment of low-frequency seismic effects of 5 point and weaker seismic events including
those caused by distant earthquakes. 相似文献