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141.
综合目前各地震成因假说而提出了地震立体网络多因复成学说,该学说包括两个基本点:地震时空分布具有立体网络性;地震是显、隐性立体网络力能结构上的一个纽结。显性网络力能主要是以应力形式作用的力能,主要来源于地球自身的运转、地壳整体收缩和地幔活动因素,表现为局部性挤压和拉伸,结果往往形成断裂、断裂带、系或其他地球物理薄弱地带。隐性网络力能主要是以连续性(区域)场和瞬间冲击、扰动形式作用的力能,主要来源于太阳、月亮及太阳系各行星因素以及宇宙膨胀复原力能、宇宙高能粒子流或慧星与地球相遇引发的流星雨,表现为区域性引拉和斥推,以及瞬间冲击力、干扰力。隐性网络力对蕴震体物质和能量进行“加载”或“卸载”,结果是广泛沟通蕴震体内部及与外部的联系、调节控制蕴震体振动方式和运动方式及其能量积累和释放、促进或诱发蕴震体发震。显、隐性网络力能叠加于蕴震体,当蕴震体自由振动被叠加振动剧烈加强即蕴震体发生共振时,引起蕴震体加速运动而处于临界态,出现降维、减熵的有序特征,在临界态蕴震体受瞬间冲击或扰动,或者与环境出现解耦,而出现突变、混沌、发生地震。基于地震立体网络多因复成学说认识提出了DZW333预测模式,预测模式包括地震成因物理模型、典型地震发生机制和地震三级预测程序3部分主要内容。DZW即地震网络学说,333即由3类显性物质单元组成,即发震地壳体、球内地幔活动体、球外天体;由3部分力能因素组成,即地壳体自动力能、地幔热压体浮沉力能、星际引斥扰动力能;有3级预测程序,即时空网络预测、形态特征预测、精确信息预测。前两级预测也属于以研究对象中的共性为基础的统计预测,应确定概率值。后一级的信息预测则是以研究对象中的特性为基础的确定性预测,不涉及概率。以唐山大地震为例作了解析。 相似文献
142.
Stefan Stange 《Journal of Seismology》2006,10(2):247-257
A method for the determination of consistent local magnitude M
L values (Richter scale, or M
WA) for earthquakes with epicentral distances ranging from 10 km through 1000 km is demonstrated. The raw data consists of nearly 1300 amplitude readings from a network of six digital seismographs in Baden–Württemberg (Southwestern Germany) during 26 months starting in 1995, later extended by another 1000 amplitude readings until 1999. Relying on most of the basics introduced by C.F. Richter a three-parameter attenuation curve (distance correction, magnitude-distance relation) for Baden–Württemberg and adjacent areas is presented. Station corrections are evaluated and the attenuation curve is calibrated with respect to other agencies for distances greater than 650 km. Reasonable parametrisations are discussed and meaningful error bars are attributed. Finally, a seventh station is incorporated by means of its station correction alone, without needing to update the attenuation curve. 相似文献
143.
Location Accuracy of the China National Seismograph Network Estimated by Repeating Events 总被引:3,自引:0,他引:3
Jiang Changsheng 《中国地震研究》2006,20(1):67-74
INTRODUCTIONDigital seismological observation in China has had a significant development in recent years,especiallysince the last five years(Liu Ruifeng,et al.,2003).For further development,it isnecessarytoassessthe monitoringcapabilityof the existingseismological network.One of theimportantassessments is the estimation of regionalizedlocation accuracy.Upto present,several approaches have been proposed to assess the location accuracy,such asthe groundtruth event approach(e.g.,Lienert,199… 相似文献
144.
145.
A modern tsunami catalogue has been compiled for the region of Cyprus-Levantine Sea in which 24 certain or possible local
tsunamis are listed from antiquity up to the present time, while six regional tsunamis, generated in the Hellenic arc, are
documented which affected the region. Another set of 13 doubtful events not included in the catalogue are discussed. Tsunami
intensities k and K were re-evaluated using the classic 6-grade and the new 12-grade intensity scales, respectively. The strongest tsunamis reported
in the region of interest are those of 551 AD, 749, 1068, 1201, 1222, 1546 and 1759, all occurring along the Levantine coast
from Gaza northward, with the exception of the 1222 wave which occurred in the Cyprean arc. The causative earthquakes, however,
occur on land and are associated with the left-lateral strike-slip Levantine rift and, as such, remain unexplained. In this
paper we speculate on the mechanism of these events. A second tsunami zone follows the Cyprean arc, where the situation of
subaqueous seismogenic sources favours the generation of tsunamis by co-seismic fault displacements. Submarine or coastal
earth slumping, however, may be an additional tsunamigenic component. Based on historical data, the average tsunami recurrence
in the Cyprus-Levantine Sea region is roughly estimated to be around 30 years, 120 years and 375 years for moderate (k/K ≥ 2/3), strong (k/K ≥ 3/5) and very strong (k/K ≥ 5/8) events, respectively. The rate of tsunami occurrence equals 0.033, 8.3 × 10−3 and 2.7 × 10−3 events/year for intensity k/K ≥ 2/3, 3/5 and 5/8, respectively. For a Poissonian (random) process the probabilities of observing at least one moderate,
strong or very strong tsunami are 0.28, 0.01 and 3 × 10−3 within 1 year, 0.81, 0.34 and 0.13 within 50 years and 0.96, 0.56 and 0.24 within 100 years, respectively. The tsunami potential
in the Cyprus-Levantine Sea area is low relative to other Mediterranean tsunamigenic regions. However, the destructiveness
of some historical events indicates the need to evaluate tsunami hazard by all available means. In addition, remote tsunamigenic
sources, such as those of 1303 and 1481 in the eastern Hellenic arc, are able to threaten the coasts of the Cyprus-Levantine
region and, therefore, such regional tsunamis should be taken into account in the evaluation of the tsunami risk of the region. 相似文献
146.
The use of logic trees in probabilistic seismic hazard analyses often involves a large number of branches that reflect the uncertainty in the selection of different models and in the selection of the parameter values of each model. The sensitivity analysis, as proposed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817], is an efficient tool that allows the construction of logic trees focusing attention on the parameters that have greater impact on the hazard.In this paper the sensitivity analysis is performed in order to identify the parameters that have the largest influence on the Western Liguria (North Western Italy) seismic hazard. The analysis is conducted for six strategic sites following the multi-parameter approach developed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796–817] and accounts for both mean hazard values and hazard values corresponding to different percentiles (e.g., 16%-ile and 84%-ile). The results are assessed in terms of the expected PGA with a 10% probability of exceedance in 50 years for rock conditions and account for both the contribution from specific source zones using the Cornell approach [Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seismol. Soc. Am. 58, 1583–1606] and the spatially smoothed seismicity [Frankel, A., 1995. Mapping seismic hazard in the Central and Eastern United States. Seismol. Res. Lett. 66, 8–21]. The influence of different procedures for calculating seismic hazard, seismic catalogues (epicentral parameters), source zone models, frequency–magnitude parameters, maximum earthquake magnitude values and attenuation relationships is considered. As a result, the sensitivity analysis allows us to identify the parameters with higher influence on the hazard. Only these parameters should be subjected to careful discussion or further research in order to reduce the uncertainty in the hazard while those with little or no effect can be excluded from subsequent logic-tree-based seismic hazard analyses. 相似文献
147.
Several source parameters (source dimensions, slip, particle velocity, static and dynamic stress drop) are determined for the moderate-size October 27th, 2004 (MW = 5.8), and the large August 30th, 1986 (MW = 7.1) and March 4th, 1977 (MW = 7.4) Vrancea (Romania) intermediate-depth earthquakes. For this purpose, the empirical Green's functions method of Irikura [e.g. Irikura, K. (1983). Semi-Empirical Estimation of Strong Ground Motions during Large Earthquakes. Bull. Dis. Prev. Res. Inst., Kyoto Univ., 33, Part 2, No. 298, 63–104., Irikura, K. (1986). Prediction of strong acceleration motions using empirical Green's function, in Proceedings of the 7th Japan earthquake engineering symposium, 151–156., Irikura, K. (1999). Techniques for the simulation of strong ground motion and deterministic seismic hazard analysis, in Proceedings of the advanced study course seismotectonic and microzonation techniques in earthquake engineering: integrated training in earthquake risk reduction practices, Kefallinia, 453–554.] is used to generate synthetic time series from recordings of smaller events (with 4 ≤ MW ≤ 5) in order to estimate several parameters characterizing the so-called strong motion generation area, which is defined as an extended area with homogeneous slip and rise time and, for crustal earthquakes, corresponds to an asperity of about 100 bar stress release [Miyake, H., T. Iwata and K. Irikura (2003). Source characterization for broadband ground-motion simulation: Kinematic heterogeneous source model and strong motion generation area. Bull. Seism. Soc. Am., 93, 2531–2545.] The parameters are obtained by acceleration envelope and displacement waveform inversion for the 2004 and 1986 events and MSK intensity pattern inversion for the 1977 event using a genetic algorithm. The strong motion recordings of the analyzed Vrancea earthquakes as well as the MSK intensity pattern of the 1977 earthquake can be well reproduced using relatively small strong motion generation areas, which corresponds to small asperities with high stress drops (300–1200 bar) and high particle velocities (3–5 m/s). These results imply a very efficient high-frequency radiation, which has to be taken into account for strong ground motion prediction, and indicate that the intermediate-depth Vrancea earthquakes are inherently different from crustal events. 相似文献
148.
The Kuril-Kamchatka seismofocal zone was thought to be a single plate approximately 90 km wide and dipping to a depth of 700 km at an angle of 40°–45°. This concept reflects primarily the physical differences (elastic wave velocities, density, temperature, etc.) between the seismofocal zone and the mantle hosting it. Detailed investigations show that the seismofocal zone proper is also heterogeneous with earthquake hypocenters variably concentrated and clustered within this zone, where both seismogenic and aseismic strata, as well as subvertical zones, can be identified. The latter are reflected in the structure and faults of the Earth’s crust and upper mantle. 相似文献
149.
Numerical Simulation of the 1918 Puerto Rico Tsunami 总被引:1,自引:0,他引:1
The Caribbean Sea region is well known for its hurricanes, and less known for tsunamis. As part of its responsibilities in hazard assessment and mitigation, the U.S.A. Federal Emergency Management Agency, and the Puerto Rico Civil Defense, funded a pilot study to perform a numerical simulation of the 1918 Puerto Rico tsunami, one of the most deadly in the region. As part of the study a review has been made of the tectonic and tsunamigenic environment around Puerto Rico, the fault parameters for the 1918 event have been estimated, and a numerical simulation has been done using a tsunami propagation and runup model obtained through the Tsunami Inundation Modeling for Exchange (TIME) program. Model results have been compared with the observed runup values all along the west coast of Puerto Rico. 相似文献
150.
Applying genetic algorithm to inversion of seismic moment tensor solution and using the data of P waveform from digital network
and initial motion directions of P waves of Taiwan network stations, we studied the moment tensor solutions and focal parameters
of the earthquake of M=7.3 on 16 September of 1994 in Taiwan Strait and other four quakes of M
L≥5.8 in the near region (21°–26°N, 115°–120°E). Among the five earthquakes, the quake of M=7.3 on September 16, 1994 in Taiwan Strait is the strongest one in the southeastern coast area since Nan’ao earthquake of
M=7.3 in 1918. The results show that moment tensor solution of M=7.3 earthquake is mainly double-couple component, and is normal fault whose fault plane is near NW. The strike of the fault
plane resembles that of the distributive bands of earthquakes before the main event and fracture pattern shown by aftershocks.
The tension stress axis of focal mechanism is about horizontal, near in NE strike, the compressive stress axis is approximately
vertical, near in NWW strike. It seems that this quake is controlled by the force of Philippine plate’s pressing Eurasian
plate in NW direction. But from the viewpoint of P axis of near vertical and T axis of near horizontal, it is a normal fault of strong tensibility. There are relatively big difference between focal mechanism
solution of this quake and those of the four other strong quakes. The complexity of source mechanism solution of these quakes
represents the complexity of the process of the strait earthquake sequences.
Contribution No. 98A01001, Institute of Geophysics, State Seismological Bureau, China.
The subject is supported and helped by Academician Yun-Tai CHEN, Profs. Qing-Yao HONG, Zhen-Xing YAO, Tian-Yu ZHENG, Yao-Lin SHI, Ji-An XU, Bo-Shou HUANG and colleague Mei-Jian AN, Xue-Reng DING, Rui-Feng LIU. De-Chong ZHANG and Ming Li provided the digital data warm-heartedly. Lin-Ying WANG offered us the catalogue of earthquakes in southeastern coastal area in China. Xi-Li WANG and Tong-Xia BAI provided us the issued annual reports data. The authors would like to express their gratitude to all of these people.
This paper is sponsored by the National Natural Science Foundation of China and Scientific and Technological Commission of
Shantou, Guangdong Province. 相似文献