Frequency–magnitude statistics and spatial correlation dimensions of earthquakes at Long Valley caldera, California     

D. J. Barton  G. R. Foulger  J. R. Henderson  & B. R. Julian 《Geophysical Journal International》1999,138(2):563-570

Intense earthquake swarms at Long Valley caldera in late 1997 and early 1998 occurred on two contrasting structures. The first is defined by the intersection of a north-northwesterly array of faults with the southern margin of the resurgent dome, and is a zone of hydrothermal upwelling. Seismic activity there was characterized by high b -values and relatively low values of D , the spatial fractal dimension of hypocentres. The second structure is the pre-existing South Moat fault, which has generated large-magnitude seismic activity in the past. Seismicity on this structure was characterized by low b -values and relatively high D . These observations are consistent with low-magnitude, clustered earthquakes on the first structure, and higher-magnitude, diffuse earthquakes on the second structure. The first structure is probably an immature fault zone, fractured on a small scale and lacking a well-developed fault plane. The second zone represents a mature fault with an extensive, coherent fault plane.  相似文献   

Statistics for Modeling Heavy Tailed Distributions in Geology: Part II. Applications     

Jef Caers  Jan Beirlant  Marc A. Maes 《Mathematical Geology》1999,31(4):411-434

In this paper, we present three diverse types of applications of extreme value statistics in geology, namely: earthquakes magnitudes, diamond values, and impact crater size distribution on terrestrial planets. Each of these applications has a different perspective toward tail modeling, yet many of these phenomena exhibit heavy or long tails which can be modeled by power laws. It is shown that the estimation of important tail characteristics, such as the extreme value index, is directly linked to the interpretation of the underlying geological process. Only the most extreme data are useful for studying such phenomena, so thresholds must be selected above which the data become power laws. In the case of earthquake magnitudes, we investigate the use of extreme value statistics in predicting large events on the global scale and for shallow intracontinental earthquakes in Asia. Large differences are found between estimates obtained from extreme value statistics and the usually applied standard statistical techniques. In the case of diamond deposits, we investigate the impact of the most precious stones in the global valuation of primary deposits. It is shown that in the case of Pareto-type behavior, the expected value of few extreme stones in the entire deposit has considerable influence on the global valuation. In the case of impact crater distributions, we study the difference between craters distributions on Earth and Mars and distributions occurring on other planets or satellites within the solar system. A striking result is that all planets display the same distributional tail except for Earth and Mars. In a concluding account, we demonstrate the apparent loghyperbolic variation in all of the above-mentioned examples.  相似文献   

Magnitude Formulae and Intensity–Magnitude Relations for Early Instrumental Earthquakes in the Iberian Region     

Elena Samardjieva  Gonzalo Payo  Jose Badal 《Natural Hazards》1999,19(2-3):189-204

The magnitudes of early instrumentally recorded earthquakes in the Iberian region (1912–1962) have been studied through processing of digitized seismograms of Wiechert seismograph and analysis of macroseismic information. A magnitude system based on instrumental registrations and macroseismic observations has been proposed. It consists of two compatible magnitude formulae depending on the total duration of seismic oscillations and on the maximum ground amplitude/period ratio of surface waves and includes correspondent intensity–magnitude relationships.  相似文献   

Characteristics of strong ground motion for typical Australian intra-plate earthquakes and their relationship with the recommended response spectra     

C. Sinadinovski  K. F. McCue  M. Somerville 《Soil Dynamics and Earthquake Engineering》2000,20(1-4)

Global epicentre maps show that the majority of earthquakes are inter-plate, although moderate to large earthquakes do occur intra-plate, i.e. within the plates. The seismicity of the Australian continent is typical of intra-plate environments and a magnitude M_L 6 earthquake has an average return period of about 5 years. Recordings of Australian intra-plate earthquakes are investigated here to characterise their frequency content, peak acceleration and duration.Due to lack of quality strong motion records of large intra-plate earthquakes at short distances, synthetic seismograms are commonly used for testing structural behaviour. An empirical Green's Function method (Geophys. Res. Lett., 5 (1978), 1–4; Proceedings of the Third International Microzonation Conference, Seattle, USA, vol. 1, (1982), pp. 447–458.) is chosen to simulate a large earthquake by summation in time of a number of smaller earthquakes or sub-events, each given a slightly different origin time to represent more realistically the propagation of a rupture along an assumed fault plane. In the first instance, recordings on rock of the magnitude M_L 2.3 aftershock of the 29 December 1989 Newcastle earthquake were used as sub-events to simulate the main shock of magnitude M_L 5.6. Validation studies for events recorded elsewhere in Australia are also considered.The response spectra of such synthetic events will be compared with the recommended spectra developed empirically from a statistical analysis of strong motion data for magnitude 5.4–6.5 intra-plate earthquakes recorded in other parts of the world and normalised to a peak ground velocity of 50 mm/s which is typical for a return period of 500 years in Australia (Australasian Structural Engineering Conference, Auckland, New Zealand, (1998), pp. 439–444.). Preliminary results from this comparison with the response spectra recommended for the Building Code of Australia show that the synthetic waveforms produced by this method are realistic and can be used to represent ground motion during typical Australian intra-plate earthquakes.  相似文献   

强震中短期前兆异常的共性特征   总被引：3，自引：0，他引：3  

陈立德 《地震》2000,20(2):7-14

强震前兆异常具有六大共性特征。地震学方面: 第一,长期阶段的平静异常,强震均发生在已发生强震震源区之间的空段上;第二,中短期阶段强震震源区之外相当大范围中小地震或震群异常活跃,震源区反而平静,形成环形或 R-t图空区。定点前兆方面;第一,异常开始时间的外早内晚特征 ;第二,异常台站空间分布的非连续性特征; 第三,短期阶段异常数量的“突增”性特征 ;第四,短临阶段异常幅度的“巨变”性特征。上述事实用已有的DD和IPE模型无法解释,可作震源硬化模型的事实基础。在强震的预报实践中,空段和空区可以作为地点判据,异常数量的增加同时伴随的巨变异常,可以作为进入短临阶段的判据。除某些强震前1~2天外,其他时段震源区内异常不明显。按传统模型指导实践,必然造成声东击西,若用已揭示的异常共性特征指导预报,则可避免上述错误。  相似文献   

Historical eruptions of Merapi Volcano, Central Java, Indonesia, 1768–1998     

B. Voight  E. K. Constantine  S. Siswowidjoyo  R. Torley 《Journal of Volcanology and Geothermal Research》2000,100(1-4)

  相似文献   

中、强震前应力场动态演变特征综合分析   总被引：4，自引：0，他引：4  

周翠英  陈虹  王红卫  郭瑞芝  王梅  郑建常 《地震》2000,(2)

使用由地震记录 P波初至波符号求取的小震综合机制解资料 ,分析研究了华北地区 4次中强地震前震源区及其附近小震应力场的动态变化。结合前人的有关研究成果 ,综合归纳了中、强地震前震源区及附近应力场的动态演变特征 ,并尝试给出了小震综合机制解参数预报地震的判据指标。  相似文献   

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李松林  赖晓玲  何加勇  田建华 《大地测量与地球动力学》2008,28(5):16-20

?????й???????????????????????????????????????????λ???????????????????????????????????????????ī?????????????????????????棬???????????????????????????????????????????????????????????????????????????????????Ч?????????????????????????????????????????????????????????????λ?????????????????????λ?????????????????????????????????????????????????????????????????????壬????????????????????????????д???  相似文献   

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李峰  韩晓玉  但卫  耿爱玲 《大地测量与地球动力学》2008,28(4):63-67

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中国大陆强震时空分布特征及2021年玛多7.4级地震后趋势分析     

王芃  邵志刚  石富强  尹晓菲 《地震》2021,41(4):1-14

对中国大陆强震活动的时空分布特征进行分析,有助于中国大陆强震趋势的判定.由于地震目录完整性的限制,目前对中国大陆强震时间间隔的分析多基于1900年以来地震目录.因为记录时长相对较短,难以排除当前强震时序特征基于偶然的可能性,并且可能导致过拟合而影响预测效果.针对上述问题,本文根据2021-2030年中国大陆地震重点危险...  相似文献