Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface r...Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster assessments.High-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral area.The results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault Zone.Moreover,dense soil liquefaction pits were triggered along the rupture trace.These events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian Plate.The western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian Plates.Both China and Türkiye have independent tectonic histories.展开更多
The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark sour...The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark source(source level:216 dB,main frequency:750 Hz,frequency bandwidth:150-1200 Hz)and a towed hydrophone streamer with 48 channels.Because the source and the towed hydrophone streamer are constantly moving according to the towing configuration,the accurate positioning of the towing hydrophone array and the moveout correction of deep-towed multichannel seismic data processing before imaging are challenging.Initially,according to the characteristics of the system and the towing streamer shape in deep water,travel-time positioning method was used to construct the hydrophone streamer shape,and the results were corrected by using the polynomial curve fitting method.Then,a new data-processing workflow for Kuiyang-ST2000 system data was introduced,mainly including float datum setting,residual static correction,phase-based moveout correction,which allows the imaging algorithms of conventional marine seismic data processing to extend to deep-towed seismic data.We successfully applied the Kuiyang-ST2000 system and methodology of data processing to a gas hydrate survey of the Qiongdongnan and Shenhu areas in the South China Sea,and the results show that the profile has very high vertical and lateral resolutions(0.5 m and 8 m,respectively),which can provide full and accurate details of gas hydrate-related and geohazard sedimentary and structural features in the South China Sea.展开更多
3D seismic and petrophysical log data interpretation of reservoir sands in “SIMA” Field, onshore Niger Delta has been undertaken in this study to ascertain the reservoir characteristics in terms of favourable struct...3D seismic and petrophysical log data interpretation of reservoir sands in “SIMA” Field, onshore Niger Delta has been undertaken in this study to ascertain the reservoir characteristics in terms of favourable structural and petrophysical parameters suitable for hydrocarbon accumulation and entrapment in the field. Horizon and fault interpretation were carried out for subsurface structural delineation. In all, seven faults (five normal and two listric faults) were mapped in the seismic section. These faults were major structure building faults corresponding to the growth and antithetic faults in the area within the well control. The antithetic fault trending northwest-southeast and the normal fault trending northeast-southwest on the structural high in the section act as good trapping mechanisms for hydrocarbon accumulations in the reservoir. From the manual and auto-tracking methods applied, several horizons were identified and mapped. The section is characterized by high amplitude with moderate-to-good continuity reflections appearing parallel to sub-parallel, mostly disturbed by some truncations which are more fault related than lithologic heterogeneity. The southwestern part is, however, characterized by low-to-high or variable amplitude reflections with poor-to-low continuity. Normal faults linked to roll-over anticlines were identified. Some fault truncations were observed due to lithologic heterogeneity. The combination of these faults acts as good traps for hydrocarbon accumulations in the reservoir. Reservoir favourable petrophysical qualities, having average NTG, porosity, permeability and water saturation of 5 m, 0.20423, 1128.219 kD and 0.458 respectively.展开更多
In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflec...In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflect actual situations and facilitate their computation and analyses.Given the importance of model building, further processing methods about traditional seismic interpretation results from Landmark should be studied and the processed result can then be directly used in numerical simulation computations.Through this data conversion procedure, Landmark and FLAC(the international general stress software) are seamlessly connected.Thus, the format conversion between the two systems and the pre-and post-processing in simulation computation is realized.A practical application indicates that this method has many advantages such as simple operation, high accuracy of the element subdivision and high speed, which may definitely satisfy the actual needs of floor grid cutting.展开更多
Through analyzing the needs of seismic data processing and interpretation,a system model based on CSCW is designed.Using the technology of CSCW to build the environment of cooperative work allows the field data acquis...Through analyzing the needs of seismic data processing and interpretation,a system model based on CSCW is designed.Using the technology of CSCW to build the environment of cooperative work allows the field data acquisition to possess the functions of remote real-time guidance by experts and remote real-time processing of the data.The model overcomes the influences and barriers existing in the areas展开更多
Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lith...Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lithologic ones. Summarized in this paper is the integrated seismic processing/interpretation technique established on the basis of pre-stack AVO processing and interpretation.Information feedbacks occurred between the pre-stack and post-stack processes so as to improve the accuracy in utilization of data and avoid pitfalls in seismic attributes. Through the integration of seismic data with geologic data, parameters that were most essential to describing hydrocarbon characteristics were determined and comprehensively appraised, and regularities of reservoir generation and distribution were described so as to accurately appraise reservoirs, delineate favorite traps and pinpoint wells.展开更多
General purpose graphic processing unit(GPU) calculation technology is gradually widely used in various fields.Its mode of single instruction,multiple threads is capable of seismic numerical simulation which has a hug...General purpose graphic processing unit(GPU) calculation technology is gradually widely used in various fields.Its mode of single instruction,multiple threads is capable of seismic numerical simulation which has a huge quantity of data and calculation steps.In this study,we introduce a GPU-based parallel calculation method of a precise integration method(PIM) for seismic forward modeling.Compared with CPU single-core calculation,GPU parallel calculating perfectly keeps the features of PIM,which has small bandwidth,high accuracy and capability of modeling complex substructures,and GPU calculation brings high computational efficiency,which means that high-performing GPU parallel calculation can make seismic forward modeling closer to real seismic records.展开更多
Geological radar probing technology finds wide application in engineering projects.The high-precision characteristics of geologic radar should be studied in connection with fine processing and interpretation. This art...Geological radar probing technology finds wide application in engineering projects.The high-precision characteristics of geologic radar should be studied in connection with fine processing and interpretation. This article discusses such issues as ( 1 ) geologic radar noise source and (2) fine processing and interpretation of radar data. It is foct^sed on bow to achieve fine processing and interpretation.展开更多
In this paper, I described the methods that I used for the creation of Xlets, which are Java applets that are developed for the IDTV environment;and the methods for online data retrieval and processing that I utilized...In this paper, I described the methods that I used for the creation of Xlets, which are Java applets that are developed for the IDTV environment;and the methods for online data retrieval and processing that I utilized in these Xlets. The themes that I chose for the Xlets of the IDTV applications are Earthquake and Tsunami Early Warning;Recent Seismic Activity Report;and Emergency Services. The online data regarding the Recent Seismic Activity Report application are provided by the Kandilli Observatory and Earthquake Research Institute (KOERI) of Bogazici University in Istanbul;while the online data for the Earthquake and Tsunami Early Warning and the Emergency Services applications are provided by the Godoro website which I used for storing (and retrieving by the Xlets) the earthquake and tsunami early warning simulation data, and the DVB network subscriber data (such as name and address information) for utilizing in the Emergency Services (Police, Ambulance and Fire Department) application. I have focused on the methodologies to use digital television as an efficient medium to convey timely and useful information regarding seismic warning data to the public, which forms the main research topic of this paper.展开更多
In order to detect fault exactly and quickly, cusp catastrophe theory is used to interpret 3D coal seismic data in this paper. By establishing a cusp model, seismic signal is transformed into standard form of cusp cat...In order to detect fault exactly and quickly, cusp catastrophe theory is used to interpret 3D coal seismic data in this paper. By establishing a cusp model, seismic signal is transformed into standard form of cusp catastrophe and catastrophe parameters, including time-domain catastrophe potential, time-domain catastrophe time, frequency-domain catastrophe potential and frequency- domain degree, are calculated. Catastrophe theory is used in 3D seismic structural interpretation in coal mine. The results show that the position of abnormality of the catastrophe parameter profile or curve is related to the location of fault, and the cusp catastrophe theory is effective to automatically pick up geology information and improve the interpretation precision in 3D seismic data.展开更多
A novel technique for automatic seismic data processing using both integral and local feature of seismograms was presented in this paper.Here,the term integral feature of seismograms refers to feature which may depict...A novel technique for automatic seismic data processing using both integral and local feature of seismograms was presented in this paper.Here,the term integral feature of seismograms refers to feature which may depict the shape of the whole seismograms.However,unlike some previous efforts which completely abandon the DIAL approach,i.e.,signal detection,phase identification,association,and event localization,and seek to use envelope cross-correlation to detect seismic events directly,our technique keeps following the DIAL approach,but in addition to detect signals corresponding to individual seismic phases,it also detects continuous wave-trains and explores their feature for phase-type identification and signal association.More concrete ideas about how to define wave-trains and combine them with various detections,as well as how to measure and utilize their feature in the seismic data processing were expatiated in the paper.This approach has been applied to the routine data processing by us for years,and test results for a 16 days' period using data from the Xinjiang seismic station network were presented.The automatic processing results have fairly low false and missed event rate simultaneously,showing that the new technique has good application prospects for improvement of the automatic seismic data processing.展开更多
Outburst floods caused by breaches of landslide dams may cause serious damages and loss of lives in downstream areas; for this reason the study of the dynamic of the process is of particular interest for hazard and ri...Outburst floods caused by breaches of landslide dams may cause serious damages and loss of lives in downstream areas; for this reason the study of the dynamic of the process is of particular interest for hazard and risk assessment. In this paper we report a field-scale landslide dam failure experiment conducted in Nantou County, in the central of Taiwan.The seismic signal generated during the dam failure was monitored using a broadband seismometer and the signal was used to study the dam failure process.We used the short-time Fourier transform(STFT) to obtain the time–frequency characteristics of the signal and analyzed the correlation between the power spectrum density(PSD) of the signal and the water level. The results indicate that the seismic signal generated during the process consisted of three components: a low-frequency band(0–1.5 Hz), an intermediate-frequency band(1.5–10 Hz) and a highfrequency band(10–45 Hz). We obtained the characteristics of each frequency band and the variations of the signal in various stages of the landslide dam failure process. We determined the cause for the signal changes in each frequency band and its relationship with the dam failure process. The PSD sediment flux estimation model was used to interpret the causes of variations in the signal energy before the dam failure and the clockwise hysteresis during the failure. Our results show that the seismic signal reflects the physical characteristics of the landslide dam failure process. The method and equipment used in this study may be used to monitor landslide dams and providing early warnings for dam failures.展开更多
A comprehensive study of the data profiles, including the 2D seismic data, single channel seismic data, shallow sections, etc., reveals that gas hydrates occur in the East China Sea. A series of special techniques are...A comprehensive study of the data profiles, including the 2D seismic data, single channel seismic data, shallow sections, etc., reveals that gas hydrates occur in the East China Sea. A series of special techniques are used in the processing of seismic data, which include enhancing the accuracy of velocity analysis and resolution, estimating the wavelet, suppressing the multiple, preserving the relative amplitude, using the DMO and AVO techniques and some special techniques in dealing with the wave impedance. The existence of gas hydrates is reflected in the subbottom profiles in the appearance of BSRs, amplitude anomalies, velocity anomalies and AVO anomalies, etc. Hence the gas hydrates can be identified and predicted. It is pointed out that the East China Sea is a favorable area of the gas hydrates resource, and the Okinawa Trough is a target area of gas hydrates reservoir.展开更多
According to the seismic and geological differences among every oil measures in mid-deep layers at west slope in Qikou Sag, varieties of new techniques on geophysics and geochemistry were introduced , such as seismic ...According to the seismic and geological differences among every oil measures in mid-deep layers at west slope in Qikou Sag, varieties of new techniques on geophysics and geochemistry were introduced , such as seismic pro-cess of target and CWS, neural network seismic microfacies cluster analysis, 3D interval velocity analysis. Taking advan-tage of the series of new techniques aims at predicting synthetically and quantitatively the deep gravity flow channel sandbody. Furthermore, considering the structural setting data, potential structural-lithologic traps were specified. As a re-sult, the geological and drilling effect is obviously promoted.展开更多
The detailed structures of the plumbing system of the early Permian Tarim flood basalt were investigated by 3-D seismic imaging.The images show that the Tarim flood basalt mainly erupted from central volcanoes
The Maqen-Jingbian wide-angle seismic reflection and refraction experiment was carried out in 1998,which aims at determining detailed structure in the crust and top of the upper mantle and understanding structural rel...The Maqen-Jingbian wide-angle seismic reflection and refraction experiment was carried out in 1998,which aims at determining detailed structure in the crust and top of the upper mantle and understanding structural relation between the northeastern Tibetan plateau and the Ordos block. The 1-D crustal models inferred by waveform inversion show strong variations in crustal structure,which can be classified into four different types:1 an Ordos platform with the Proterozoic crust and two high-velocity layers in the northeast section,2 a transitional crust between the northeastern Tibetan plateau and the Ordos block across the Haiyuan earthquake zone,3 the Qilian orogenic zone in the central part,and 4 the Qinling orogenic zone in the southwestern section. The Moho depth increases from ～42 km to ～62 km from the NE part to the SW part of the profile. The crystalline crust consists of the upper crust and lower crust in northeastern Tibetan plateau. There is an obviously low P-wave velocity layer dipping northeastward,which is 12-13 km thick,at the bottom of the upper crust in Qinling orogenic zone and Haiyuan earthquake zone. The lower crust is characterized by alternating high and low P-wave velocity layers. Beneath Ordos block,i.e.,the NE part of the profile,the crust shows quite a smooth increase in P-wave ve-locity down to the Moho at a depth of about 42 km.展开更多
基金funded by the Basic Research Program of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant Nos.CEAIEF20220102,2021IEF0505,and CEAIEF2022050502)the National Natural Science Foundation of China(Grant Nos.42072248 and 42041006)the National Key Research and Development Program of China(Grant Nos.2021YFC3000601-3 and 2019YFE0108900)。
文摘Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious casualties.Understanding the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster assessments.High-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral area.The results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault Zone.Moreover,dense soil liquefaction pits were triggered along the rupture trace.These events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian Plate.The western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian Plates.Both China and Türkiye have independent tectonic histories.
基金Supported by the National Key R&D Program of China(No.2016YFC0303900)the Laoshan Laboratory(Nos.MGQNLM-KF201807,LSKJ202203604)the National Natural Science Foundation of China(No.42106072)。
文摘The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark source(source level:216 dB,main frequency:750 Hz,frequency bandwidth:150-1200 Hz)and a towed hydrophone streamer with 48 channels.Because the source and the towed hydrophone streamer are constantly moving according to the towing configuration,the accurate positioning of the towing hydrophone array and the moveout correction of deep-towed multichannel seismic data processing before imaging are challenging.Initially,according to the characteristics of the system and the towing streamer shape in deep water,travel-time positioning method was used to construct the hydrophone streamer shape,and the results were corrected by using the polynomial curve fitting method.Then,a new data-processing workflow for Kuiyang-ST2000 system data was introduced,mainly including float datum setting,residual static correction,phase-based moveout correction,which allows the imaging algorithms of conventional marine seismic data processing to extend to deep-towed seismic data.We successfully applied the Kuiyang-ST2000 system and methodology of data processing to a gas hydrate survey of the Qiongdongnan and Shenhu areas in the South China Sea,and the results show that the profile has very high vertical and lateral resolutions(0.5 m and 8 m,respectively),which can provide full and accurate details of gas hydrate-related and geohazard sedimentary and structural features in the South China Sea.
文摘3D seismic and petrophysical log data interpretation of reservoir sands in “SIMA” Field, onshore Niger Delta has been undertaken in this study to ascertain the reservoir characteristics in terms of favourable structural and petrophysical parameters suitable for hydrocarbon accumulation and entrapment in the field. Horizon and fault interpretation were carried out for subsurface structural delineation. In all, seven faults (five normal and two listric faults) were mapped in the seismic section. These faults were major structure building faults corresponding to the growth and antithetic faults in the area within the well control. The antithetic fault trending northwest-southeast and the normal fault trending northeast-southwest on the structural high in the section act as good trapping mechanisms for hydrocarbon accumulations in the reservoir. From the manual and auto-tracking methods applied, several horizons were identified and mapped. The section is characterized by high amplitude with moderate-to-good continuity reflections appearing parallel to sub-parallel, mostly disturbed by some truncations which are more fault related than lithologic heterogeneity. The southwestern part is, however, characterized by low-to-high or variable amplitude reflections with poor-to-low continuity. Normal faults linked to roll-over anticlines were identified. Some fault truncations were observed due to lithologic heterogeneity. The combination of these faults acts as good traps for hydrocarbon accumulations in the reservoir. Reservoir favourable petrophysical qualities, having average NTG, porosity, permeability and water saturation of 5 m, 0.20423, 1128.219 kD and 0.458 respectively.
基金Projects 50221402, 50490271 and 50025413 supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China (2009CB219603, 2009 CB724601, 2006CB202209 and 2005CB221500)+1 种基金the Key Project of the Ministry of Education (306002)the Program for Changjiang Scholars and Innovative Research Teams in Universities of MOE (IRT0408)
文摘In order to carry out numerical simulation using geologic structural data obtained from Landmark(seismic interpretation system), underground geological structures are abstracted into mechanical models which can reflect actual situations and facilitate their computation and analyses.Given the importance of model building, further processing methods about traditional seismic interpretation results from Landmark should be studied and the processed result can then be directly used in numerical simulation computations.Through this data conversion procedure, Landmark and FLAC(the international general stress software) are seamlessly connected.Thus, the format conversion between the two systems and the pre-and post-processing in simulation computation is realized.A practical application indicates that this method has many advantages such as simple operation, high accuracy of the element subdivision and high speed, which may definitely satisfy the actual needs of floor grid cutting.
文摘Through analyzing the needs of seismic data processing and interpretation,a system model based on CSCW is designed.Using the technology of CSCW to build the environment of cooperative work allows the field data acquisition to possess the functions of remote real-time guidance by experts and remote real-time processing of the data.The model overcomes the influences and barriers existing in the areas
文摘Nowadays, it becomes very urgent to find remain oil under the oil shortage worldwide.However, most of simple reservoirs have been discovered and those undiscovered are mostly complex structural, stratigraphic and lithologic ones. Summarized in this paper is the integrated seismic processing/interpretation technique established on the basis of pre-stack AVO processing and interpretation.Information feedbacks occurred between the pre-stack and post-stack processes so as to improve the accuracy in utilization of data and avoid pitfalls in seismic attributes. Through the integration of seismic data with geologic data, parameters that were most essential to describing hydrocarbon characteristics were determined and comprehensively appraised, and regularities of reservoir generation and distribution were described so as to accurately appraise reservoirs, delineate favorite traps and pinpoint wells.
基金supported by the National Natural Science Foundation of China (Nos 40974066 and 40821062)National Basic Research Program of China (No 2007CB209602)
文摘General purpose graphic processing unit(GPU) calculation technology is gradually widely used in various fields.Its mode of single instruction,multiple threads is capable of seismic numerical simulation which has a huge quantity of data and calculation steps.In this study,we introduce a GPU-based parallel calculation method of a precise integration method(PIM) for seismic forward modeling.Compared with CPU single-core calculation,GPU parallel calculating perfectly keeps the features of PIM,which has small bandwidth,high accuracy and capability of modeling complex substructures,and GPU calculation brings high computational efficiency,which means that high-performing GPU parallel calculation can make seismic forward modeling closer to real seismic records.
基金This project is sponsored by The Special Fund of Scientific Instruments of National Natural Science Foundation of China(50127402) and The Geophysical Responses to The High-resolution Exploration for Coal-methane of 973 Program(2002CB211707).
文摘Geological radar probing technology finds wide application in engineering projects.The high-precision characteristics of geologic radar should be studied in connection with fine processing and interpretation. This article discusses such issues as ( 1 ) geologic radar noise source and (2) fine processing and interpretation of radar data. It is foct^sed on bow to achieve fine processing and interpretation.
文摘In this paper, I described the methods that I used for the creation of Xlets, which are Java applets that are developed for the IDTV environment;and the methods for online data retrieval and processing that I utilized in these Xlets. The themes that I chose for the Xlets of the IDTV applications are Earthquake and Tsunami Early Warning;Recent Seismic Activity Report;and Emergency Services. The online data regarding the Recent Seismic Activity Report application are provided by the Kandilli Observatory and Earthquake Research Institute (KOERI) of Bogazici University in Istanbul;while the online data for the Earthquake and Tsunami Early Warning and the Emergency Services applications are provided by the Godoro website which I used for storing (and retrieving by the Xlets) the earthquake and tsunami early warning simulation data, and the DVB network subscriber data (such as name and address information) for utilizing in the Emergency Services (Police, Ambulance and Fire Department) application. I have focused on the methodologies to use digital television as an efficient medium to convey timely and useful information regarding seismic warning data to the public, which forms the main research topic of this paper.
文摘In order to detect fault exactly and quickly, cusp catastrophe theory is used to interpret 3D coal seismic data in this paper. By establishing a cusp model, seismic signal is transformed into standard form of cusp catastrophe and catastrophe parameters, including time-domain catastrophe potential, time-domain catastrophe time, frequency-domain catastrophe potential and frequency- domain degree, are calculated. Catastrophe theory is used in 3D seismic structural interpretation in coal mine. The results show that the position of abnormality of the catastrophe parameter profile or curve is related to the location of fault, and the cusp catastrophe theory is effective to automatically pick up geology information and improve the interpretation precision in 3D seismic data.
文摘A novel technique for automatic seismic data processing using both integral and local feature of seismograms was presented in this paper.Here,the term integral feature of seismograms refers to feature which may depict the shape of the whole seismograms.However,unlike some previous efforts which completely abandon the DIAL approach,i.e.,signal detection,phase identification,association,and event localization,and seek to use envelope cross-correlation to detect seismic events directly,our technique keeps following the DIAL approach,but in addition to detect signals corresponding to individual seismic phases,it also detects continuous wave-trains and explores their feature for phase-type identification and signal association.More concrete ideas about how to define wave-trains and combine them with various detections,as well as how to measure and utilize their feature in the seismic data processing were expatiated in the paper.This approach has been applied to the routine data processing by us for years,and test results for a 16 days' period using data from the Xinjiang seismic station network were presented.The automatic processing results have fairly low false and missed event rate simultaneously,showing that the new technique has good application prospects for improvement of the automatic seismic data processing.
基金financially supported by the External Cooperation Program of Bureau of International Co-operation,Chinese Academy of Sciences(131551KYSB20130003)the Risk Evaluation and Mitigation Technology of Barrier Lake Project of China Communications Construction Company Limited(2013318J01100)+2 种基金the Key Technologies R&D Program of Sichuan Province in China(2014SZ0163)the Special Program for International S&T Cooperation projects of China(Grant No.2012DFA20980)National Natural Science Foundation of China(Grant No.51479179)
文摘Outburst floods caused by breaches of landslide dams may cause serious damages and loss of lives in downstream areas; for this reason the study of the dynamic of the process is of particular interest for hazard and risk assessment. In this paper we report a field-scale landslide dam failure experiment conducted in Nantou County, in the central of Taiwan.The seismic signal generated during the dam failure was monitored using a broadband seismometer and the signal was used to study the dam failure process.We used the short-time Fourier transform(STFT) to obtain the time–frequency characteristics of the signal and analyzed the correlation between the power spectrum density(PSD) of the signal and the water level. The results indicate that the seismic signal generated during the process consisted of three components: a low-frequency band(0–1.5 Hz), an intermediate-frequency band(1.5–10 Hz) and a highfrequency band(10–45 Hz). We obtained the characteristics of each frequency band and the variations of the signal in various stages of the landslide dam failure process. We determined the cause for the signal changes in each frequency band and its relationship with the dam failure process. The PSD sediment flux estimation model was used to interpret the causes of variations in the signal energy before the dam failure and the clockwise hysteresis during the failure. Our results show that the seismic signal reflects the physical characteristics of the landslide dam failure process. The method and equipment used in this study may be used to monitor landslide dams and providing early warnings for dam failures.
文摘A comprehensive study of the data profiles, including the 2D seismic data, single channel seismic data, shallow sections, etc., reveals that gas hydrates occur in the East China Sea. A series of special techniques are used in the processing of seismic data, which include enhancing the accuracy of velocity analysis and resolution, estimating the wavelet, suppressing the multiple, preserving the relative amplitude, using the DMO and AVO techniques and some special techniques in dealing with the wave impedance. The existence of gas hydrates is reflected in the subbottom profiles in the appearance of BSRs, amplitude anomalies, velocity anomalies and AVO anomalies, etc. Hence the gas hydrates can be identified and predicted. It is pointed out that the East China Sea is a favorable area of the gas hydrates resource, and the Okinawa Trough is a target area of gas hydrates reservoir.
文摘According to the seismic and geological differences among every oil measures in mid-deep layers at west slope in Qikou Sag, varieties of new techniques on geophysics and geochemistry were introduced , such as seismic pro-cess of target and CWS, neural network seismic microfacies cluster analysis, 3D interval velocity analysis. Taking advan-tage of the series of new techniques aims at predicting synthetically and quantitatively the deep gravity flow channel sandbody. Furthermore, considering the structural setting data, potential structural-lithologic traps were specified. As a re-sult, the geological and drilling effect is obviously promoted.
文摘The detailed structures of the plumbing system of the early Permian Tarim flood basalt were investigated by 3-D seismic imaging.The images show that the Tarim flood basalt mainly erupted from central volcanoes
基金supported by National Natural Science Foundation of China (Grant No. 90814012)Contribution No.200909,Geophysical Exploration Center,China Earthquake Administration(CEA)
文摘The Maqen-Jingbian wide-angle seismic reflection and refraction experiment was carried out in 1998,which aims at determining detailed structure in the crust and top of the upper mantle and understanding structural relation between the northeastern Tibetan plateau and the Ordos block. The 1-D crustal models inferred by waveform inversion show strong variations in crustal structure,which can be classified into four different types:1 an Ordos platform with the Proterozoic crust and two high-velocity layers in the northeast section,2 a transitional crust between the northeastern Tibetan plateau and the Ordos block across the Haiyuan earthquake zone,3 the Qilian orogenic zone in the central part,and 4 the Qinling orogenic zone in the southwestern section. The Moho depth increases from ～42 km to ～62 km from the NE part to the SW part of the profile. The crystalline crust consists of the upper crust and lower crust in northeastern Tibetan plateau. There is an obviously low P-wave velocity layer dipping northeastward,which is 12-13 km thick,at the bottom of the upper crust in Qinling orogenic zone and Haiyuan earthquake zone. The lower crust is characterized by alternating high and low P-wave velocity layers. Beneath Ordos block,i.e.,the NE part of the profile,the crust shows quite a smooth increase in P-wave ve-locity down to the Moho at a depth of about 42 km.
