Jupiter is one of the top priorities for deep space exploration in China and other countries.The structure of Jupiter’s interior,in particular,is a crucial but still unclear scientific topic.This paper discusses curr...Jupiter is one of the top priorities for deep space exploration in China and other countries.The structure of Jupiter’s interior,in particular,is a crucial but still unclear scientific topic.This paper discusses current scientific understanding of Jupiter’s interior by summarizing the history of past and current exploration and data analysis.We review recent space-based and ground-based observation methods and analyze their feasibility.To gain new insight into the internal structure of Jupiter,we propose to study Jupiter’s innards by planetary seismology.Ground-based observation,namely the Jupiter Seismologic Interferometer Polarization Imager(SIPI)in Lenghu,will be developed to obtain the Doppler velocity distribution on the surface of Jupiter and identify oscillation signals.Lenghu has observation conditions that are not only exceptional in China but even in the world,capable of providing novel insight into the interior of Jupiter.This will also be the first study in China of the interior of Jupiter using asteroseismology,which has significant implications for China’s plans to explore Jupiter via spacecraft-mounted instruments.展开更多
Climate change has been a matter of discourse for the last several decades. Much research has been conducted regarding the causes and impacts of climate change around the world. The current research contributes to the...Climate change has been a matter of discourse for the last several decades. Much research has been conducted regarding the causes and impacts of climate change around the world. The current research contributes to the knowledge of the influence of climate change on our environment, with emphasis on earthquake occurrences in the region of Indonesia. Using global temperature anomaly as a measure of climate change, and earthquake data in Indonesia for the period 1900-2022, the paper seeks to find a relationship (if any) between the two variables. Statistical methods used include normal distribution analysis, linear regression and correlation test. The results show peculiar patterns in the progression of earthquake occurrences as well as global temperature anomaly occurring in the same time periods. The findings also indicated that the magnitudes of earthquakes remained unaffected by global temperature anomalies over the years. Nonetheless, there appears to be a potential correlation between temperature anomalies and the frequency of earthquake occurrences. As per the results, an increase in temperature anomaly is associated with a higher frequency of earthquakes.展开更多
According to the definition, seismology is a science that studies the processes and causes of seismic phenomena and the structure of the Earth, i.e. a scientific discipline that studies the movement of blocks of rocks...According to the definition, seismology is a science that studies the processes and causes of seismic phenomena and the structure of the Earth, i.e. a scientific discipline that studies the movement of blocks of rocks of the Earth’s crust and mantle and related phenomena. Seismology conducts research in the following areas and is designed to scientifically explain two main issues: 1) Study of the nature of seismic phenomena and the internal structure of the Earth. Why, how and where do seismic impacts occur? 2) Protecting humanity from the catastrophic consequences of seismic events. Is it possible to predict seismic impacts? Like any other scientific discipline, seismology is obliged to follow the laws of science and its fundamental principles. This article is devoted to the description of violations of the fundamental laws of science committed by seismologists in the study of seismic processes and raises the question of compliance of the stated research directions with the current level of development of sciences. Answering point No. 1, regarding the structure of the Earth, it is possible to recognize some successes of seismology, which nevertheless cause great doubts in the scientific community of geophysicists, because if the stratigraphic data of ultra-deep wells often refute [1] the conclusions made by seismologists on the structure of the Earth’s crust at shallow depth, then to assert something unambiguously about the structure of the mantle and at the present stage, seismology cannot. Answering the main questions of seismology, why seismic phenomena occur, and how earthquake energy is formed, seismologists have not had, and have not. Answering point No. 2, we can confidently say that in the matter of forecasting seismic phenomena, seismology has not advanced one iota over the past century, and as seismologists have been confused in the search for earthquake prediction algorithms, they are also confused without any hope of success. All that modern seismology can “boast” is the theory of Elastic recoil [2], the absurdity of which does not cause any doubt among the progressive part of geophysicists. But, the fact that most of the leading scientists-seismologists continue to piously believe the conclusions of the Elastic Recoil theory puts seismology in a humiliating position, because Mr. Reid’s theory is the clearest example of a false theory based on scientific incompetence of scientists, a model of brazen violation of the fundamental laws of science and the foundation of false and ignorant conclusions. Based on the results achieved, or rather on their absence, we regret to draw a sad conclusion: modern seismology is in the deepest decline, the cause of which is the incompetence of researchers as a result of their catastrophically low level of academic training, who stuff the scientific community with scientific geophysical rubbish, breeding similar ignoramuses in seismology. We understand that by asserting this, we offend most seismologists, but it is impossible to continue to tolerate this state of affairs in geophysics, because: “Amicus plato, sed magis amica est veritas.” Obviously, the time has come for a new meteorologist, Alfred Wagener [3], who will come and teach seismologists not to guess on coffee grounds, but to investigate seismic processes using the fundamental laws of science. In this article, we not only investigate the reasons for the unsatisfactory state of affairs in seismology, but also give our answers to the questions, of why earthquakes occur and how seismic energy is formed.展开更多
Having been a seemingly unreachable ideal for decades,3-D full-waveform inversion applied to massive seismic datasets has become reality in recent years.Often achieving unprecedented resolution,it has provided new ins...Having been a seemingly unreachable ideal for decades,3-D full-waveform inversion applied to massive seismic datasets has become reality in recent years.Often achieving unprecedented resolution,it has provided new insight into the structure of the Earth,from the upper few metres of soil to the entire globe.Motivated by these successes,the technology is now being translated to medical ultrasound and non-destructive testing.Despite remarkable progress,the computational cost of fullwaveform inversion continues to be a major concern.It limits the amount of data that can be exploited,and it largely inhibits quantitative and comprehensive uncertainty analyses.These notes complement a presentation on recent developments in full-waveform inversion that are intended to reduce computational cost and assimilate more data,thereby improving tomographic resolution.The suite of strategies includes flexible and user-friendly spectral-element simulations,the design of wavefieldadapted meshes that harness prior information on wavefield geometry,dynamic mini-batch optimisation that naturally takes advantage of data redundancies,and collaborative multi-scale updating to jointly constrain crustal and mantle structure.展开更多
Following crustal stress and the tectonic evolutions that lead to the triggering of seisms is still premature, for technological reasons. Instead, in view of the energies involved, which are in the order of kilotons, ...Following crustal stress and the tectonic evolutions that lead to the triggering of seisms is still premature, for technological reasons. Instead, in view of the energies involved, which are in the order of kilotons, it is necessary to collect symptoms manifesting inside the Earth. The greater the stresses produced, the more evident will be the seismic signals manifesting on a global scale. From the point of view of teaching, it is proposed to study seismology in secondary schools using an ＂evidential＂ paradigm, rather than the ＂Galileian＂ sort. This will require a more modern approach, one that considers non-linearity an investigation model that is more in line with the Natural Science approach. To this effect, also the seismology lab is transformed from a place where reality is ＂reproduced＂, into a setting where comparisons are made in the intrinsic presence of clues rather than proofs. The instruments used to carry out this project, which is taking its first steps in an experimental form in Parma （Italy）, can be reproduced at low cost, but without forsaking precision measurements. The instruments in question are those used to detect radio anomalies, acoustic emissions produced in the deepest layers of the terrestrial crust, and variations in gravity that require a computer to interface data and elaborate signals 24/7.展开更多
The scientific goal of the Anninghe seismic array is to investigate the detailed geometry of the Anninghe fault and the velocity structure of the fault zone.This 2D seismic array is composed of 161 stations forming su...The scientific goal of the Anninghe seismic array is to investigate the detailed geometry of the Anninghe fault and the velocity structure of the fault zone.This 2D seismic array is composed of 161 stations forming sub-rectangular geometry along the Anninghe fault,which covers 50 km and 150 km in the fault normal and strike directions,respectively,with~5 km intervals.The data were collected between June 2020 and June 2021,with some level of temporal gaps.Two types of instruments,i.e.QS-05A and SmartSolo,are used in this array.Data quality and examples of seismograms are provided in this paper.After the data protection period ends(expected in June 2024),researchers can request a dataset from the National Earthquake Science Data Center.展开更多
Realistically predicting earthquake is critical for seismic risk assessment,prevention and safe design of major structures.Due to the complex nature of seismic events,it is challengeable to efficiently identify the ea...Realistically predicting earthquake is critical for seismic risk assessment,prevention and safe design of major structures.Due to the complex nature of seismic events,it is challengeable to efficiently identify the earthquake response and extract indicative features from the continuously detected seismic data.These challenges severely impact the performance of traditional seismic prediction models and obstacle the development of seismology in general.Taking their advantages in data analysis,artificial intelligence(AI) techniques have been utilized as powerful statistical tools to tackle these issues.This typically involves processing massive detected data with severe noise to enhance the seismic performance of structures.From extracting meaningful sensing data to unveiling seismic events that are below the detection level,AI assists in identifying unknown features to more accurately predicting the earthquake activities.In this focus paper,we provide an overview of the recent AI studies in seismology and evaluate the performance of the major AI techniques including machine learning and deep learning in seismic data analysis.Furthermore,we envision the future direction of the AI methods in earthquake engineering which will involve deep learning-enhanced seismology in an internet-of-things(IoT) platform.展开更多
On March 26,2010 an underwater explosion(UWE)led to the sinking of the ROKS Cheonan.The official Multinational Civilian-Military Joint Investigation Group(MCMJIG)report concluded that the cause of the underwater explo...On March 26,2010 an underwater explosion(UWE)led to the sinking of the ROKS Cheonan.The official Multinational Civilian-Military Joint Investigation Group(MCMJIG)report concluded that the cause of the underwater explosion was a 250 kg net explosive weight(NEW)detonation at a depth of 6 9 m from a DPRK"CHT-02D"torpedo.Kim and Gitterman(2012a)determined the NEW and seismic magnitude as 136 kg at a depth of approximately 8m and 2.04,respectively using basic hydrodynamics based on theoretical and experimental methods as well as spectral analysis and seismic methods.The purpose of this study was to clarify the cause of the UWE via more detailed methods using bubble dynamics and simulation of propellers as well as forensic seismology.Regarding the observed bubble pulse period of 0.990 s,0.976 s and 1.030 s were found in case of a 136NEW at a detonation depth of 8 m using the boundary element method(BEM)and 3D bubble shape simulations derived for a 136kg NEW detonation at a depth of 8 m approximately 5 m portside from the hull centerline.Here we show through analytical equations,models and 3D bubble shape simulations that the most probable cause of this underwater explosion was a 136 kg NEW detonation at a depth of 8m attributable to a ROK littoral"land control"mine(LCM).展开更多
In transversely isotropic media with a vertical symmetry axis （VTI）, the converted-wave （C-wave） moveout over intermediate-to-far offsets is determined by four parameters. These are the C-wave stacking velocity Vc...In transversely isotropic media with a vertical symmetry axis （VTI）, the converted-wave （C-wave） moveout over intermediate-to-far offsets is determined by four parameters. These are the C-wave stacking velocity Vc2 , the vertical and effective velocity ratios γ0 and γeff, and the anisotropic parameter χeff. We refer to the four parameters as the C-wave stacking velocity model. The purpose of C-wave velocity analysis is to determine this stacking velocity model. The C-wave stacking velocity model Vc2, γ0, γeff, and χeff can be determined from P-and C-wave reflection moveout data. However, error propagation is a severe problem in C-wave reflection-moveout inversion. The current short-spread stacking velocity as deduced from hyperbolic moveout does not provide sufficient accuracy to yield meaningful inverted values for the anisotropic parameters. The non-hyperbolic moveout over intermediate-offsets （x/z from 1.0 to 1.5） is no longer negligible and can be quantified using a background γ. Non-hyperbolic analysis with a γ correction over the intermediate offsets can yield Vc2 with errors less than 1% for noise free data. The procedure is very robust, allowing initial guesses of γ with up to 20% errors. It is also applicable for vertically inhomogeneous anisotropic media. This improved accuracy makes it possible to estimate anisotropic parameters using 4C seismic data. Two practical work flows are presented for this purpose： the double-scanning flow and the single-scanning flow. Applications to synthetic and real data show that the two flows yield results with similar accuracy but the single-scanning flow is more efficient than the double-scanning flow.展开更多
Both earthquake seismology and structural seismology rely on observations, which in turn contribute critically to the development of seismology, especially in recent years.In order to understand specific geologic stru...Both earthquake seismology and structural seismology rely on observations, which in turn contribute critically to the development of seismology, especially in recent years.In order to understand specific geologic structures and interior processes of the Earth, seismic arrays are widely展开更多
BP neural networks is used to mid-term earthquake prediction in this paper. Some usual prediction parameters of seismology are used as the import units of neural networks. And the export units of neural networks is ca...BP neural networks is used to mid-term earthquake prediction in this paper. Some usual prediction parameters of seismology are used as the import units of neural networks. And the export units of neural networks is called as the character parameter W_0 describing enhancement of seismicity. We applied this method to space scanning of North China. The result shows that the mid-term anomalous zone of W_0-value usually appeared obviously around the future epicenter 1~3 years before earthquake. It is effective to mid-term prediction.展开更多
A Sino\|French refraction\|reflection experiment was conducted in October 1998 in the northeastern edge of the Tibetan Plateau from the Qiang Tang through the north Kunlun block.The successive wide\|angle reflection t...A Sino\|French refraction\|reflection experiment was conducted in October 1998 in the northeastern edge of the Tibetan Plateau from the Qiang Tang through the north Kunlun block.The successive wide\|angle reflection traveltime curves are modeled trying to keep the minimum structure. First results obtained along this 700km transect, show the contrast of crustal structure between the three blocks crossed and the state of the crustal material.North of the Kunlun suture, a change of the Moho depth appears from the Qaidam basin, 55km, to the south approaching the Kunlun range, 65km. But the main crustal characteristic is a great thickness of upper crustal material and the lack of lower crust. This implies a crustal average velocity of 6 2km/s, which is much lower than the worldwide average of 6 45km/s. Interpretations of this crustal column may consider, assuming the crust had been normal that while its upper part thickened the lower one was transported away, underthrust to the south or to depth. Alternatively the velocity in the lower crust may have been changed by metamorphism.展开更多
My journey on the wiggles with Don started from February 2008,when I got an opportunity to visit the Caltech Seismolab as a visiting PhD student,which was made possible via Dr.Sidao Ni’s recommendation.A previous stu...My journey on the wiggles with Don started from February 2008,when I got an opportunity to visit the Caltech Seismolab as a visiting PhD student,which was made possible via Dr.Sidao Ni’s recommendation.A previous student of Don,Sidao was a professor at the School of Earth and Space Sciences(ESS)at the University of Science and Technology of China(USTC)at that time.Sidao offered the“Computational Seismology”class at USTC where I learned a lot about the modern developments in seismology.I also met Sidao many times to discuss a wide range of research topics,I believe it is a style he inherited from his experiences with Don and other professors in Seismolab.展开更多
基金the National Natural Science Foundation of China(42222408)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021027)the Key Research Program of the Institute of Geology and Geophysics,CAS(Grant IGGCAS-201904).
文摘Jupiter is one of the top priorities for deep space exploration in China and other countries.The structure of Jupiter’s interior,in particular,is a crucial but still unclear scientific topic.This paper discusses current scientific understanding of Jupiter’s interior by summarizing the history of past and current exploration and data analysis.We review recent space-based and ground-based observation methods and analyze their feasibility.To gain new insight into the internal structure of Jupiter,we propose to study Jupiter’s innards by planetary seismology.Ground-based observation,namely the Jupiter Seismologic Interferometer Polarization Imager(SIPI)in Lenghu,will be developed to obtain the Doppler velocity distribution on the surface of Jupiter and identify oscillation signals.Lenghu has observation conditions that are not only exceptional in China but even in the world,capable of providing novel insight into the interior of Jupiter.This will also be the first study in China of the interior of Jupiter using asteroseismology,which has significant implications for China’s plans to explore Jupiter via spacecraft-mounted instruments.
文摘Climate change has been a matter of discourse for the last several decades. Much research has been conducted regarding the causes and impacts of climate change around the world. The current research contributes to the knowledge of the influence of climate change on our environment, with emphasis on earthquake occurrences in the region of Indonesia. Using global temperature anomaly as a measure of climate change, and earthquake data in Indonesia for the period 1900-2022, the paper seeks to find a relationship (if any) between the two variables. Statistical methods used include normal distribution analysis, linear regression and correlation test. The results show peculiar patterns in the progression of earthquake occurrences as well as global temperature anomaly occurring in the same time periods. The findings also indicated that the magnitudes of earthquakes remained unaffected by global temperature anomalies over the years. Nonetheless, there appears to be a potential correlation between temperature anomalies and the frequency of earthquake occurrences. As per the results, an increase in temperature anomaly is associated with a higher frequency of earthquakes.
文摘According to the definition, seismology is a science that studies the processes and causes of seismic phenomena and the structure of the Earth, i.e. a scientific discipline that studies the movement of blocks of rocks of the Earth’s crust and mantle and related phenomena. Seismology conducts research in the following areas and is designed to scientifically explain two main issues: 1) Study of the nature of seismic phenomena and the internal structure of the Earth. Why, how and where do seismic impacts occur? 2) Protecting humanity from the catastrophic consequences of seismic events. Is it possible to predict seismic impacts? Like any other scientific discipline, seismology is obliged to follow the laws of science and its fundamental principles. This article is devoted to the description of violations of the fundamental laws of science committed by seismologists in the study of seismic processes and raises the question of compliance of the stated research directions with the current level of development of sciences. Answering point No. 1, regarding the structure of the Earth, it is possible to recognize some successes of seismology, which nevertheless cause great doubts in the scientific community of geophysicists, because if the stratigraphic data of ultra-deep wells often refute [1] the conclusions made by seismologists on the structure of the Earth’s crust at shallow depth, then to assert something unambiguously about the structure of the mantle and at the present stage, seismology cannot. Answering the main questions of seismology, why seismic phenomena occur, and how earthquake energy is formed, seismologists have not had, and have not. Answering point No. 2, we can confidently say that in the matter of forecasting seismic phenomena, seismology has not advanced one iota over the past century, and as seismologists have been confused in the search for earthquake prediction algorithms, they are also confused without any hope of success. All that modern seismology can “boast” is the theory of Elastic recoil [2], the absurdity of which does not cause any doubt among the progressive part of geophysicists. But, the fact that most of the leading scientists-seismologists continue to piously believe the conclusions of the Elastic Recoil theory puts seismology in a humiliating position, because Mr. Reid’s theory is the clearest example of a false theory based on scientific incompetence of scientists, a model of brazen violation of the fundamental laws of science and the foundation of false and ignorant conclusions. Based on the results achieved, or rather on their absence, we regret to draw a sad conclusion: modern seismology is in the deepest decline, the cause of which is the incompetence of researchers as a result of their catastrophically low level of academic training, who stuff the scientific community with scientific geophysical rubbish, breeding similar ignoramuses in seismology. We understand that by asserting this, we offend most seismologists, but it is impossible to continue to tolerate this state of affairs in geophysics, because: “Amicus plato, sed magis amica est veritas.” Obviously, the time has come for a new meteorologist, Alfred Wagener [3], who will come and teach seismologists not to guess on coffee grounds, but to investigate seismic processes using the fundamental laws of science. In this article, we not only investigate the reasons for the unsatisfactory state of affairs in seismology, but also give our answers to the questions, of why earthquakes occur and how seismic energy is formed.
基金support from the European Union’s Horizon 2020 research and innovation program through the ERC Starting Grant,entitled“The Collaborative Seismic Earth Model”(Grant No.714069)provided by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No.955515(SPIN ITN)+1 种基金the ChEESE project(Folch et al.,2023)which secured funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No.823844。
文摘Having been a seemingly unreachable ideal for decades,3-D full-waveform inversion applied to massive seismic datasets has become reality in recent years.Often achieving unprecedented resolution,it has provided new insight into the structure of the Earth,from the upper few metres of soil to the entire globe.Motivated by these successes,the technology is now being translated to medical ultrasound and non-destructive testing.Despite remarkable progress,the computational cost of fullwaveform inversion continues to be a major concern.It limits the amount of data that can be exploited,and it largely inhibits quantitative and comprehensive uncertainty analyses.These notes complement a presentation on recent developments in full-waveform inversion that are intended to reduce computational cost and assimilate more data,thereby improving tomographic resolution.The suite of strategies includes flexible and user-friendly spectral-element simulations,the design of wavefieldadapted meshes that harness prior information on wavefield geometry,dynamic mini-batch optimisation that naturally takes advantage of data redundancies,and collaborative multi-scale updating to jointly constrain crustal and mantle structure.
文摘Following crustal stress and the tectonic evolutions that lead to the triggering of seisms is still premature, for technological reasons. Instead, in view of the energies involved, which are in the order of kilotons, it is necessary to collect symptoms manifesting inside the Earth. The greater the stresses produced, the more evident will be the seismic signals manifesting on a global scale. From the point of view of teaching, it is proposed to study seismology in secondary schools using an ＂evidential＂ paradigm, rather than the ＂Galileian＂ sort. This will require a more modern approach, one that considers non-linearity an investigation model that is more in line with the Natural Science approach. To this effect, also the seismology lab is transformed from a place where reality is ＂reproduced＂, into a setting where comparisons are made in the intrinsic presence of clues rather than proofs. The instruments used to carry out this project, which is taking its first steps in an experimental form in Parma （Italy）, can be reproduced at low cost, but without forsaking precision measurements. The instruments in question are those used to detect radio anomalies, acoustic emissions produced in the deepest layers of the terrestrial crust, and variations in gravity that require a computer to interface data and elaborate signals 24/7.
基金supported by the National Key Research and Development Program of China(No.2018YFC1503401).
文摘The scientific goal of the Anninghe seismic array is to investigate the detailed geometry of the Anninghe fault and the velocity structure of the fault zone.This 2D seismic array is composed of 161 stations forming sub-rectangular geometry along the Anninghe fault,which covers 50 km and 150 km in the fault normal and strike directions,respectively,with~5 km intervals.The data were collected between June 2020 and June 2021,with some level of temporal gaps.Two types of instruments,i.e.QS-05A and SmartSolo,are used in this array.Data quality and examples of seismograms are provided in this paper.After the data protection period ends(expected in June 2024),researchers can request a dataset from the National Earthquake Science Data Center.
基金the startup fund from the Swanson School of Engineering at the University of Pittsburgh。
文摘Realistically predicting earthquake is critical for seismic risk assessment,prevention and safe design of major structures.Due to the complex nature of seismic events,it is challengeable to efficiently identify the earthquake response and extract indicative features from the continuously detected seismic data.These challenges severely impact the performance of traditional seismic prediction models and obstacle the development of seismology in general.Taking their advantages in data analysis,artificial intelligence(AI) techniques have been utilized as powerful statistical tools to tackle these issues.This typically involves processing massive detected data with severe noise to enhance the seismic performance of structures.From extracting meaningful sensing data to unveiling seismic events that are below the detection level,AI assists in identifying unknown features to more accurately predicting the earthquake activities.In this focus paper,we provide an overview of the recent AI studies in seismology and evaluate the performance of the major AI techniques including machine learning and deep learning in seismic data analysis.Furthermore,we envision the future direction of the AI methods in earthquake engineering which will involve deep learning-enhanced seismology in an internet-of-things(IoT) platform.
文摘On March 26,2010 an underwater explosion(UWE)led to the sinking of the ROKS Cheonan.The official Multinational Civilian-Military Joint Investigation Group(MCMJIG)report concluded that the cause of the underwater explosion was a 250 kg net explosive weight(NEW)detonation at a depth of 6 9 m from a DPRK"CHT-02D"torpedo.Kim and Gitterman(2012a)determined the NEW and seismic magnitude as 136 kg at a depth of approximately 8m and 2.04,respectively using basic hydrodynamics based on theoretical and experimental methods as well as spectral analysis and seismic methods.The purpose of this study was to clarify the cause of the UWE via more detailed methods using bubble dynamics and simulation of propellers as well as forensic seismology.Regarding the observed bubble pulse period of 0.990 s,0.976 s and 1.030 s were found in case of a 136NEW at a detonation depth of 8 m using the boundary element method(BEM)and 3D bubble shape simulations derived for a 136kg NEW detonation at a depth of 8 m approximately 5 m portside from the hull centerline.Here we show through analytical equations,models and 3D bubble shape simulations that the most probable cause of this underwater explosion was a 136 kg NEW detonation at a depth of 8m attributable to a ROK littoral"land control"mine(LCM).
基金This work is funded by the Edinburgh Anisotropy Project of the British Geological Survey.
文摘In transversely isotropic media with a vertical symmetry axis （VTI）, the converted-wave （C-wave） moveout over intermediate-to-far offsets is determined by four parameters. These are the C-wave stacking velocity Vc2 , the vertical and effective velocity ratios γ0 and γeff, and the anisotropic parameter χeff. We refer to the four parameters as the C-wave stacking velocity model. The purpose of C-wave velocity analysis is to determine this stacking velocity model. The C-wave stacking velocity model Vc2, γ0, γeff, and χeff can be determined from P-and C-wave reflection moveout data. However, error propagation is a severe problem in C-wave reflection-moveout inversion. The current short-spread stacking velocity as deduced from hyperbolic moveout does not provide sufficient accuracy to yield meaningful inverted values for the anisotropic parameters. The non-hyperbolic moveout over intermediate-offsets （x/z from 1.0 to 1.5） is no longer negligible and can be quantified using a background γ. Non-hyperbolic analysis with a γ correction over the intermediate offsets can yield Vc2 with errors less than 1% for noise free data. The procedure is very robust, allowing initial guesses of γ with up to 20% errors. It is also applicable for vertically inhomogeneous anisotropic media. This improved accuracy makes it possible to estimate anisotropic parameters using 4C seismic data. Two practical work flows are presented for this purpose： the double-scanning flow and the single-scanning flow. Applications to synthetic and real data show that the two flows yield results with similar accuracy but the single-scanning flow is more efficient than the double-scanning flow.
文摘Both earthquake seismology and structural seismology rely on observations, which in turn contribute critically to the development of seismology, especially in recent years.In order to understand specific geologic structures and interior processes of the Earth, seismic arrays are widely
文摘BP neural networks is used to mid-term earthquake prediction in this paper. Some usual prediction parameters of seismology are used as the import units of neural networks. And the export units of neural networks is called as the character parameter W_0 describing enhancement of seismicity. We applied this method to space scanning of North China. The result shows that the mid-term anomalous zone of W_0-value usually appeared obviously around the future epicenter 1~3 years before earthquake. It is effective to mid-term prediction.
文摘A Sino\|French refraction\|reflection experiment was conducted in October 1998 in the northeastern edge of the Tibetan Plateau from the Qiang Tang through the north Kunlun block.The successive wide\|angle reflection traveltime curves are modeled trying to keep the minimum structure. First results obtained along this 700km transect, show the contrast of crustal structure between the three blocks crossed and the state of the crustal material.North of the Kunlun suture, a change of the Moho depth appears from the Qaidam basin, 55km, to the south approaching the Kunlun range, 65km. But the main crustal characteristic is a great thickness of upper crustal material and the lack of lower crust. This implies a crustal average velocity of 6 2km/s, which is much lower than the worldwide average of 6 45km/s. Interpretations of this crustal column may consider, assuming the crust had been normal that while its upper part thickened the lower one was transported away, underthrust to the south or to depth. Alternatively the velocity in the lower crust may have been changed by metamorphism.
文摘My journey on the wiggles with Don started from February 2008,when I got an opportunity to visit the Caltech Seismolab as a visiting PhD student,which was made possible via Dr.Sidao Ni’s recommendation.A previous student of Don,Sidao was a professor at the School of Earth and Space Sciences(ESS)at the University of Science and Technology of China(USTC)at that time.Sidao offered the“Computational Seismology”class at USTC where I learned a lot about the modern developments in seismology.I also met Sidao many times to discuss a wide range of research topics,I believe it is a style he inherited from his experiences with Don and other professors in Seismolab.
