The use of ocean bottom seismometers provides an effective means of studying the process and the dynamic of cold seeps by continuously recording micro-events produced by sub-seafloor fluid migration.We deployed a four...The use of ocean bottom seismometers provides an effective means of studying the process and the dynamic of cold seeps by continuously recording micro-events produced by sub-seafloor fluid migration.We deployed a four-component Ocean Bottom Seismometer(OBS)at an active site of the Haima cold seep from 6 November to 19 November in 2021.Here,we present the results of this short-term OBS monitoring.We first examine the OBS record manually to distinguish(by their distinctive seismographic signatures)four types of events:shipping noises,vibrations from our remotely operated vehicle(ROV)operations,local earthquakes,and short duration events(SDEs).Only the SDEs are further discussed in this work.Such SDEs are similar to those observed in other sea areas and are interpreted to be correlated with sub-seafloor fluid migration.In the OBS data collected during the 14-day monitoring period.We identify five SDEs.Compared to the SDE occurrence rate observed in other cold seep regions,five events is rather low,from which it could be inferred that fluid migration,and subsequent gas seepage,is not very active at the Haima site.This conclusion agrees with multi-beam and chemical observations at that site.Our observations thus provide further constraint on the seepage activity in this location.This is the first time that cold seep-related SDEs have been identified in the South China Sea,expanding the list of sea areas where SDEs are now linked to cold seep fluid migration.展开更多
Three-component Ocean Bottom Seismometers, portable land stations and marine air gun seismic sources were used to carry out an onshore-offshore deep seismic profile in northeastern South China Sea. This profile, orien...Three-component Ocean Bottom Seismometers, portable land stations and marine air gun seismic sources were used to carry out an onshore-offshore deep seismic profile in northeastern South China Sea. This profile, orientated in NNW-SSE, was as long as 500 km and perpendicular to the strike of regional tectonics. The offshore data were processed in Taiwan Ocean University using a number of available software and the onshore data were analyzed in South China Sea Institute of Oceanology by new-written programs and public software. Preliminary results show that the seismic data are in good quality and contain rich information of deep structure. Seismic phases, e.g. Pg, PmP and Pn, are identified in the offset range 5～220 kin, which will provide an important dataset for the deep crustal structure and oil-gas basin evolution studies of this region.展开更多
The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely use...The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.展开更多
First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tom...First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tomography,most were written in compiled languages and lack sufficient extendibility for new algorithms and functionalities.In this work,we develop an open-source,selfcontained FAST package based on MATLAB,one of the most popular interpreted scientific programming languages,with a focus on ocean bottom seismometer refraction traveltime tomography.Our package contains a complete traveltime tomography workflow,including ray-tracing-based first-arrival traveltime computation,linearized inversion,quality control,and high-quality visualization.We design the package as a modular toolbox,making it convenient to integrate new algorithms and functionalities as needed.At the current stage,our package is most efficient for performing FAST for two-dimensional ocean bottom seismometer surveys.We demonstrate the efficacy and accuracy of our package by using a synthetic data example based on a modified Marmousi model.展开更多
基金supported by the Key Research and Development Project of Guangdong Province(Grant:2020B1111510001)supported by the Project of Sanya Yazhou Bay Science and Technology City(Grant No:SCKJ-JYRC-2022-14)the National Natural Science Foundation of China(Grant No:92262304).
文摘The use of ocean bottom seismometers provides an effective means of studying the process and the dynamic of cold seeps by continuously recording micro-events produced by sub-seafloor fluid migration.We deployed a four-component Ocean Bottom Seismometer(OBS)at an active site of the Haima cold seep from 6 November to 19 November in 2021.Here,we present the results of this short-term OBS monitoring.We first examine the OBS record manually to distinguish(by their distinctive seismographic signatures)four types of events:shipping noises,vibrations from our remotely operated vehicle(ROV)operations,local earthquakes,and short duration events(SDEs).Only the SDEs are further discussed in this work.Such SDEs are similar to those observed in other sea areas and are interpreted to be correlated with sub-seafloor fluid migration.In the OBS data collected during the 14-day monitoring period.We identify five SDEs.Compared to the SDE occurrence rate observed in other cold seep regions,five events is rather low,from which it could be inferred that fluid migration,and subsequent gas seepage,is not very active at the Haima site.This conclusion agrees with multi-beam and chemical observations at that site.Our observations thus provide further constraint on the seepage activity in this location.This is the first time that cold seep-related SDEs have been identified in the South China Sea,expanding the list of sea areas where SDEs are now linked to cold seep fluid migration.
基金Supported by SCSIO(LYQY200302)the Chinese Ministry of Science and Technology(G2000046701)+2 种基金the Guangdong Department of Science and Technology(2002C32604)the Guangdong Natural Science Foundation(021557)the National Natural Science Foundation of China(4000161958).
文摘Three-component Ocean Bottom Seismometers, portable land stations and marine air gun seismic sources were used to carry out an onshore-offshore deep seismic profile in northeastern South China Sea. This profile, orientated in NNW-SSE, was as long as 500 km and perpendicular to the strike of regional tectonics. The offshore data were processed in Taiwan Ocean University using a number of available software and the onshore data were analyzed in South China Sea Institute of Oceanology by new-written programs and public software. Preliminary results show that the seismic data are in good quality and contain rich information of deep structure. Seismic phases, e.g. Pg, PmP and Pn, are identified in the offset range 5～220 kin, which will provide an important dataset for the deep crustal structure and oil-gas basin evolution studies of this region.
基金supported by the National Key R&D Program of China(No.2021YFC2801200)the National Natural Science Foundation of China(No.42076224)the Fundamental Research Funds for the Central Universities(No.201964015)。
文摘The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.
基金financially supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (Grant No. GML2019 ZD0207)supported by the Guangzhou Municipal Science and Technology Bureau (Grant No. 202102021054)
文摘First-arrival seismic traveltime tomography(FAST)is a well-established technique to estimate subsurface velocity structures.Although several existing open-source packages are available for first-arrival traveltime tomography,most were written in compiled languages and lack sufficient extendibility for new algorithms and functionalities.In this work,we develop an open-source,selfcontained FAST package based on MATLAB,one of the most popular interpreted scientific programming languages,with a focus on ocean bottom seismometer refraction traveltime tomography.Our package contains a complete traveltime tomography workflow,including ray-tracing-based first-arrival traveltime computation,linearized inversion,quality control,and high-quality visualization.We design the package as a modular toolbox,making it convenient to integrate new algorithms and functionalities as needed.At the current stage,our package is most efficient for performing FAST for two-dimensional ocean bottom seismometer surveys.We demonstrate the efficacy and accuracy of our package by using a synthetic data example based on a modified Marmousi model.
