Research on inversion of average stress field by genetic algorithms

ＲｅｓｅａｒｃｈｏｎｉｎｖｅｒｓｉｏｎｏｆａｖｅｒａｇｅｓｔｒｅｓｆｉｅｌｄｂｙｇｅｎｅｔｉｃａｌｇｏｒｉｔｈｍｓＸＩＮＧ－ＸＩＮＤＵ（杜兴信）ＨＵＩ－ＬＩＮＧＺＨＡＮＧ（张惠玲）ＸＩＵ－ＬＩＮＧＬＵ（鲁秀玲）ＣＨＵＮ－ＳＨＥＮＧＺＨＡＮＧ（张春生...     

Two-step interface and velocity inversion—— Study o e of the Tangshan seismic region

ｎｔｒｏｄｕｃｔｉｏｎＩｎｒｅｃｅｎｔｔｅｎｙｅａｒｓ,ｒｅｓｅａｒｃｈｅｓｏｎｔｈｅ３Ｄｃｒｕｓｔａｌｓｔｒｕｃｔｕｒｅａｎｄｔｅｃｔｏｎｉｃｓｈａｖｅｂｅｅｎｐａｉｄｍｏｒｅａｎｄｍｏｒｅａｔｅｎｔｉｏｎ,ｓｔｕｄｉｅｓｏｆｒｅｌｅｖａｎｔｍｅ...     

The correlation between the characteristics of seismic wave propagation in Western Caucasus and the geological–tectonic features of the region

The relationship between the characteristics of seismic waves in the Western Caucasus and the geological-tectonic structure of the region is studied for identifying the specificity of seismic propagation in the mountainous regions with a complicated geological structure and forecasting the characteristics of the propagation from the geological and tectonic data. The interpretation is presented for the estimates of the Q-factor of the medium (Q(f) ~ 55f^0.9 in the region of Sochi and Q(f) ~ 90f^0.7 in the region of Anapa), seismic wave enhancement in the upper crustal layers (A(f) ~ 1), and peak ground acceleration residuals, which were previously determined from the records of the local earthquakes and show the distributions of local variations in the parameters of seismic wave radiation and propagation. The obtained characteristics are interpreted in the context of the up-to-date information about the tectonic, geological, and deep structure of the epicentral zones in the Western Caucasus and neighboring territory of the Black Sea. The discrepancies revealed in the low-frequency behavior of the Q-factor in the vicinities of Sochi and Anapa is accounted for by the spatial scale and character of tectonic dislocations of the rocks in these regions. The local variations in the parameters of seismic radiation and propagation are probably related to the geological features of the region such as the fault structures, including the thrusts, shatter zones, oblique seismic boundaries, variations in the thickness and consolidation of the sedimentary cover, as well as the peculiarities in the structure and material composition of the basement.     

Research on Micro-relief of Active Faults on the Coast of Southeast Fujian and Its Adjacent Area

On the southeast coast of Fujian and its adjacent area, the NE-trending Changle-Zhao′an fault zone and several NW-trending faults that are genetically related to the former are well developed. With micro-relief analysis, the paper deals with the Quaternary activity of the faults and the tectonic stress field since the late Pleistocene in this region. The results indicate that the micro-relief of the NE-trending Changle-Zhao′an fault zone and the genetically related NW-trending faults is characterized by vertical and horizontal movements since the Quaternary; the faults in the region have undergone two active stages since the Quaternary, i.e. early Quaternary and late Pleistocene; since the late Pleistocene, the movement of the NE-trending faults showed a right-lateral strike-slip, while that of NW-trending faults a left-lateral strike-slip, indicating a NWW-SEE oriented horizontal principal stress of the regional tectonic stress field     

The inversion of anelastic coefficient, source parameters and site respond using genetic algorithm

It gradually becomes a common work using large seismic wave data to obtain source parameters, such as seismic moment, break radius, stress drop, with completing of digital seismic network in China (Hough, et al, 1999; Bindi, et al, 2001). These parameters are useful on earthquake prediction and seismic hazard analysis. Although the computation methods of source parameters are simple in principle and the many research works have been done, it is not easy to obtain the parameters accurately. Th…     

Inversion of source parameters for moderate and small earthquakes in Beijing region

Introduction Beijing and the adjacent regions is a significant seismically active area and many geoscien- tists have studied to different extents the non-elastic attenuation and source parameters in the area. GAO et al (1986) and ZHUO et al (1990) studied the coda Q in the Beijing region by the method of dominant frequency and mechanical frequency division with the simulated data. With the con- tinuous construction of digital seismic station network, the digital data are more favorably used…     

The inversion of anelastic coefficient,source parameters and site respond using genetic algorithm

It gradually becomes a common work using large seismic wave data to obtain source parameters, such as seismic moment, break radius, stress drop, with completingof digital seismic network in China (Hough, et al, 1999; Bindi, et al, 2001). These parameters are useful on earthquake prediction and seismic hazard analysis.Although the computation methods of source parameters are simple in principle and the many research works have been done, it is not easy to obtain the parameters accurately. There are two factors affecting the stability of computation results. The first one is the effect of spread path and site respond on signal. According to the research results, there are different geometrical spreading coefficients on different epicenter distance. The better method is to introduce trilinear geometrical spreading model (Atkinson, Mereu, 1992; Atkinson, Boore, 1995; WONG, et al, 2002). In addition, traditional site respond is estimated by comparing with rock station, such as linear inversion method (Andrews, 1982), but the comparative estimation will introduce some errors when selecting different stations. Some recent research results show that site respond is not flat for rock station (Moya, et al, 2000; ZHANG,. et al, 2001; JIN, et al, 2000; Dutta, et al, 2001). The second factor is to obtain low-frequency level and corner frequency fromdisplacement spectrum. Because the source spectrum model is nonlinear function,these values are obtained by eye. The subjectivity is strong. The small change of corner frequency will affect significantly the result of stress drop.     

Travel time tomography inversion and the deep structure of the southern Tibet

ＴｒａｖｅｌｔｉｍｅｔｏｍｏｇｒａｐｈｙｉｎｖｅｒｓｉｏｎａｎｄｔｈｅｄｅｅｐｓｔｒｕｃｔｕｒｅｏｆｔｈｅｓｏｕｔｈｅｒｎＴｉｂｅｔＱＩＮＧ－ＴＩＡＮＬＵ１）（吕庆田）,ＭＥＩ－ＪＩＡＮＧ１）（姜枚）,ＫＡＩ－ＹＩＭＡ１）（马开义）,Ａ．Ｈｉｒｎ２...     

Study on inelastic attenuation coefficient, site response and source parameters in Shanxi region

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…     

Research on the effect estimation of seismic safety evaluation

IntroductionItisdefinitelystipulatedintheLawofthePeople'sRepublicofChinaonProtectingagainstandMitigatingEarthquakeDisastersthattheseismicsafetyevaluationmustbemadeformajorprojects(includinglifelineprojects)and,accordingtotheresultsobtained,theseismicresistancerequirementsshouldbedetermined.Thenecessityofseismicsafetyevaluationhasbeenrecog-nizedgradually,butthetopicontheeffectofsafetyevaluationhasnotbeenreferredmuch.Gener-allyspeaking,althoughmostpeopleapprovethesocialeffectofsafetyevaluatio…     

Research on the Characteristics of Large Earthquake Activity on the Active Tectonic Boundaries on the Chinese Mainland

INTRODUCTIONThe active blocks refer tothe geologic units that formedinlate Cenozoic (100 ~120 ka BP) andhave been highly active as fault zones since late Quaternary with relatively uniform motion styles(Zhang Guomin,et al .,2000 ;Zhang Peizhen,et al .,2003) .The active blocks are relativelyintactand have uniformmotion modalities ,their boundary zones (also called the active boundaries) are thelocalized or centralized zones of interactions and differential movement among the active block…     

Evaluation of the feasibility of recovering the magma chamber’s parameters by 3D Bayesian statistical inversion of synthetic MT data

Feasibility of recovering the magma chamber’s parameters by 3D Bayesian statistical inversion of magnetotelluric data is estimated for the simplified conductivity model of the Vesuvios volcano. The results indicate that in the lack of prior information and data, the most efficient approach may consist in successive estimation of the geometry and the depth of the anomaly followed by estimation of the electric conductivity distribution in it. The horizontal boundaries of the target could be outlined by the high gradients of the impedance determinant phase pseudosections determined by the upward analytical continuation of the anomalous electromagnetic fields from the relief surface to the artificial reference plane located above the summit of the volcano. The vertical boundaries and the target extension as well as the electric conductivity could be estimated successively by means of 3D Bayesian statistical inversion of the collected magnetotelluric data carried out in the domain delimited by the estimated horizontal boundaries.     

Research on the Result of Calibration for the Location of the Seismic Array in Shanghai

The paper proposes the calibration theory and methods for the Shanghai seismic array and analyzes the calibration results. As a result, the calibration results for the seismic array based on 2 typical earthquakes have been drawn; the difference of calibration results between Hokkaido and Honshu region in Japan is investigated. And calibration results of different directions, different epicenter distances and different magnitudes are probed into. The result shows that the location of earthquakes on the Shanghai seismic array is greatly improved.     

Research on the seismogenic environment for deep earthquake and the cause of earthquakes in Xinjiang and its adjacent areas

ＲｅｓｅａｒｃｈｏｎｔｈｅｓｅｉｓｍｏｇｅｎｉｃｅｎｖｉｒｏｎｍｅｎｔｆｏｒｄｅｅｐｅａｒｔｈｑｕａｋｅａｎｄｔｈｅｃａｕｓｅｏｆｅａｒｔｈｑｕａｋｅｓｉｎＸｉｎｊｉａｎｇａｎｄｉｔｓａｄｊａｃｅｎｔａｒｅａｓＱｉａｎｇＬＩ（李强）；Ｒｕｉ－Ｆｅｎｇ...     

Kinematic features of the seismogenic fault of the Tangshan earthquake and the recurrence period of large earthquakes

ＫｉｎｅｍａｔｉｃｆｅａｔｕｒｅｓｏｆｔｈｅｓｅｉｓｍｏｇｅｎｉｃｆａｕｌｔｏｆｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅａｎｄｔｈｅｒｅｃｕｒｒｅｎｃｅｐｅｒｉｏｄｏｆｌａｒｇｅｅａｒｔｈｑｕａｋｅｓＪＩＥＬＩＵ１）（刘洁）ＨＵＩ－ＺＨＥＮＳＯＮ...     

Source parameters of the Gonghe,Qinghai Province,China,earthquake from inversion of digital broadband waveform data

ＳｏｕｒｃｅｐａｒａｍｅｔｅｒｓｏｆｔｈｅＧｏｎｇｈｅ，ＱｉｎｇｈａｉＰｒｏｖｉｎｃｅ，Ｃｈｉｎａ，ｅａｒｔｈｑｕａｋｅｆｒｏｍｉｎｖｅｒｓｉｏｎｏｆｄｉｇｉｔａｌｂｒｏａｄｂａｎｄｗａｖｅｆｏｒｍｄａｔａＬＩ－ＳＨＥＮＧＸＵ（许立生）ａｎｄＹＵＮ...     

Research on the Effects of the Contents of Radioactive Elements on Granularity and Climate Change： An Example of SZK1 and SZK2 Drill Holes Strata in the Fuzhou Basin

INTRODUCTIONFuzhou basin is a faulted basin developed during the mid-late Quaternary,filled with marine ,terrestrial and alternating marine-terrestrial facies sediments (Lin,1979 ;Lan,et al .,1986 ; Han,etal .,1992 ;Ding,et al .,1992 ; Wang,et al .,2000 ; Wang,et al .,2002) .Inthe basin,concealedfaults are distributed. With the support of a project entitled“Testing exploration of active fault inurban area”of the National Development and ReformCommission,two drill holes (SZK1 and S…     

Discussion on origin of Pn velocity variationin China and adjacent region

IntroductionInrecentyears,theresultsfromresearchesonwavevelocitystructureofuppermostmantleusingMohorefractionwavesindicatethattheclearlateralvelocityvariationandanisotropyexistintheuppermostmantle(Hearn,1996,1999;Mele,etal,1998;WANG,etal,2002).Astotheoriginofvelocitylateralvariation,thegeneralconsiderationisthatitmayberelatedtothemate-rialcomposition,pressureandtemperatureintheuppermostmantle(Hearn,1984,1999;Beghouletal,1993).Theseismicanisotropyoftheuppermostmantleisnowanestablishedfactan…     

Research on the seismic fortification level of offshore platform in Bohai Sea and adjacent areas

Introduction Offshore platform is the main facility for exploitation of ocean resources, e.g. oil and gas. Nearly 6 000 platforms have been built in the world, 100 among them in China, another 100 will be erected in China in the coming 5 years. The current aseismic design code commonly used in the world is RP2A-WSD based on the seismic hazard zone in the coastal waters of the United States, which is compiled by American Petroleum Institute (American Petroleum Institute, 2002). No specif…