The seismo-electromagnetic(EM)method is an important geophysical method that plays a major role in the observation of seismic anomalies related to earthquake precursors.It is the most promising method for a breakthrou...The seismo-electromagnetic(EM)method is an important geophysical method that plays a major role in the observation of seismic anomalies related to earthquake precursors.It is the most promising method for a breakthrough in short-term earthquake prediction.The digital transformation and network upgrading implemented in the“Ninth five-year plan”and“Tenth five-year plan”have optimized the original observation system,improved the quality of observed data,enriched the seismicelectromagnetic information,and enhanced the analysis capability and timeliness of seismic-electromagnetic anomalies.These improvements are of major importance for the research on seismo-electromagnetics as well as for the development of new technologies.Since the beginning of the 21 st century,China has launched a satellite named CSES that was designed for the generation and study of seismo-electromagnetic data and built a high-power transmitting source and a new CSELF observation network that is used specifically for earthquake monitoring.This platform has promoted the full-time three-dimensional EM monitoring and the identification of earthquake anomalies.Based on the study of anomalies related to earthquake precursors,the physical and numerical simulations,and the study on generation mechanism of anomalies in China,we summarize the characteristics of earthquake EM anomalies and discuss the advantages and disadvantages of different EM observation methods.Finally,considering the related questions of the seismo-electromagnetic prediction and implementing the recent developments both in China and abroad,we review the current status of seismo-electromagnetic research and propose strategies for future research.展开更多
Microorganisms in natural environments are crucial in maintaining the material and energy cycle and the ecological balance of the environment.However,it is challenging to delineate environmental microbes'actual me...Microorganisms in natural environments are crucial in maintaining the material and energy cycle and the ecological balance of the environment.However,it is challenging to delineate environmental microbes'actual metabolic pathways and intraspecific heterogeneity because most microorganisms cannot be cultivated.Raman spectroscopy is a culture-independent technique that can collect molecular vibration profiles from cells.It can reveal the physiological and biochemical information at the single-cell level rapidly and non-destructively in situ.The first part of this review introduces the principles,advantages,progress,and analytical methods of Raman spectroscopy applied in environmental microbiology.The second part summarizes the applications of Raman spectroscopy combined with stable isotope probing(SIP),fluorescence in situ hybridization(FISH),Raman-activated cell sorting and genomic sequencing,and machine learning in microbiological studies.Finally,this review discusses expectations of Raman spectroscopy and future advances to be made in identifying microorganisms,especially for uncultured microorganisms.展开更多
The Linfen rift is a Cenozoic extensional rift with significant seismicity and seismic hazards.Studies of this rift shed light on deep dynamic processes and seismogenic mechanisms relevant to crustal structure and sei...The Linfen rift is a Cenozoic extensional rift with significant seismicity and seismic hazards.Studies of this rift shed light on deep dynamic processes and seismogenic mechanisms relevant to crustal structure and seismic activity.We first conducted a joint inversion of receiver functions and surface wave dispersion on waveform data collected from 27 broadband seismic stations to image the crustal S-wave velocity in the Linfen rift and its surroundings.We then relocated the source parameters for 10 earthquake events with depths>20 km and studied the relationship between crustal S-wave velocity and seismicity.The results show that low-velocity zones of different scales exist in the middle-lower crust,and that the depth of the seismogenic layer gradually increases from^25 km in the south to^34 km in the north,roughly corresponding to the bottom of the low-velocity zone.We found that most of the relocated earthquakes occurred in the low-velocity zone at depths of 18 km to 34 km,with the deepest at 32 km.Two of the greatest historic earthquakes,Linfen(Ms 7.75)in 1695 and Hongtong(Ms 8.0)in 1303,occurred at the bottom of the high-velocity zone at depths of 12 km to 18 km.Our results,combined with previous studies,suggest that the upwelling mantle material below the rift did not remarkably affect the velocity structure from the bottom of the seismogenic layer down to the uppermost mantle nor heat the crust.It is likely that neither crustal-scale faults nor mantle earthquakes exist in the Linfen rift.展开更多
Active faults pose a great threat to urban security.As the largest NW-trend active fault in Beijing area,the Nankou-Sunhe fault plays an important role in earthquake disaster and city construction.In this study,we col...Active faults pose a great threat to urban security.As the largest NW-trend active fault in Beijing area,the Nankou-Sunhe fault plays an important role in earthquake disaster and city construction.In this study,we collect continuous ambient noise data recorded by 43 temporary short-period seismograph between September 21th to October 12th 2019 to investigate the near-surface structure beneath the Nankou-Sunhe fault by using ambient noise tomography(ANT)and horizontal-to-vertical spectral ratio(HVSR)method.From ambient noise processing,fundamental-mode Rayleigh wave signals are clearly observed in the frequency band of 0.4-2.5 Hz.Then direct surface-wave inversion algorithm is applied to calculate the 3D shear-wave velocity model.Our results show that there is a sharp velocity contrast across the Nankou-Sunhe fault,with low velocities down to about 2 km on the hanging wall and high velocity on the footwall of the fault.According to the geological investigation,the low velocities are related to thicker sediments and Jurassic volcanic rock below which are the cap rock of the hydrothermal system.From the HVSR analysis,the HVSR curves of the sites near the fault shows double-peak,one less than 1 Hz and the other centered 7 Hz.After converting frequency to depth by the empirical equation,the results show that the thickness of sediments is thinned from southwest to northeast,which generally agrees well to field survey.Our results provide high-resolution near-surface structure for future study on disaster risk reduction and urban planning.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant Nos.2017YFC1500103&2018YFC1503506)the Project for Basic Research Work of the Institute of Geology,China Earthquake Administration(Grant No.IGCEA1919)+1 种基金the National Natural Science Foundation of China(Grant Nos.41374077,42074086&41674156)the National Major Science and Technology Infrastructure Project(Grant No.15212Z0000001)。
文摘The seismo-electromagnetic(EM)method is an important geophysical method that plays a major role in the observation of seismic anomalies related to earthquake precursors.It is the most promising method for a breakthrough in short-term earthquake prediction.The digital transformation and network upgrading implemented in the“Ninth five-year plan”and“Tenth five-year plan”have optimized the original observation system,improved the quality of observed data,enriched the seismicelectromagnetic information,and enhanced the analysis capability and timeliness of seismic-electromagnetic anomalies.These improvements are of major importance for the research on seismo-electromagnetics as well as for the development of new technologies.Since the beginning of the 21 st century,China has launched a satellite named CSES that was designed for the generation and study of seismo-electromagnetic data and built a high-power transmitting source and a new CSELF observation network that is used specifically for earthquake monitoring.This platform has promoted the full-time three-dimensional EM monitoring and the identification of earthquake anomalies.Based on the study of anomalies related to earthquake precursors,the physical and numerical simulations,and the study on generation mechanism of anomalies in China,we summarize the characteristics of earthquake EM anomalies and discuss the advantages and disadvantages of different EM observation methods.Finally,considering the related questions of the seismo-electromagnetic prediction and implementing the recent developments both in China and abroad,we review the current status of seismo-electromagnetic research and propose strategies for future research.
基金This work was financially supported by the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.K19313901)the National Natural Science Foundation of China(91851210,42141003)+4 种基金the State Key R&D project of China grant(No.2018YFA0605800)the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925173954005)the Guangdong-Shenzhen Joint Fund(2021B1515120080)the Shenzhen Key Laboratory of Marine Archaea Geo-Omics,Southern University of Science and Technology(ZDSYS201802081843490)the financial support from China Postdoctoral Science Foundation(2020M682769).
文摘Microorganisms in natural environments are crucial in maintaining the material and energy cycle and the ecological balance of the environment.However,it is challenging to delineate environmental microbes'actual metabolic pathways and intraspecific heterogeneity because most microorganisms cannot be cultivated.Raman spectroscopy is a culture-independent technique that can collect molecular vibration profiles from cells.It can reveal the physiological and biochemical information at the single-cell level rapidly and non-destructively in situ.The first part of this review introduces the principles,advantages,progress,and analytical methods of Raman spectroscopy applied in environmental microbiology.The second part summarizes the applications of Raman spectroscopy combined with stable isotope probing(SIP),fluorescence in situ hybridization(FISH),Raman-activated cell sorting and genomic sequencing,and machine learning in microbiological studies.Finally,this review discusses expectations of Raman spectroscopy and future advances to be made in identifying microorganisms,especially for uncultured microorganisms.
基金We also thank editors and two anonymous reviewers for their constructive reviews.This work is supported by the DREAM Project of the National Key R&D Program of China(No.2016YFC0600402)the National Natural Science Foundation of China(Grant No.41604056).
文摘The Linfen rift is a Cenozoic extensional rift with significant seismicity and seismic hazards.Studies of this rift shed light on deep dynamic processes and seismogenic mechanisms relevant to crustal structure and seismic activity.We first conducted a joint inversion of receiver functions and surface wave dispersion on waveform data collected from 27 broadband seismic stations to image the crustal S-wave velocity in the Linfen rift and its surroundings.We then relocated the source parameters for 10 earthquake events with depths>20 km and studied the relationship between crustal S-wave velocity and seismicity.The results show that low-velocity zones of different scales exist in the middle-lower crust,and that the depth of the seismogenic layer gradually increases from^25 km in the south to^34 km in the north,roughly corresponding to the bottom of the low-velocity zone.We found that most of the relocated earthquakes occurred in the low-velocity zone at depths of 18 km to 34 km,with the deepest at 32 km.Two of the greatest historic earthquakes,Linfen(Ms 7.75)in 1695 and Hongtong(Ms 8.0)in 1303,occurred at the bottom of the high-velocity zone at depths of 12 km to 18 km.Our results,combined with previous studies,suggest that the upwelling mantle material below the rift did not remarkably affect the velocity structure from the bottom of the seismogenic layer down to the uppermost mantle nor heat the crust.It is likely that neither crustal-scale faults nor mantle earthquakes exist in the Linfen rift.
基金supported by Beijing Natural Science Foundation(No.8212041)National Natural Science Foundation of China(Nos.41874063 and U1939203)Shanghai Sheshan National Geophysical Observatory(No.2020K02).
文摘Active faults pose a great threat to urban security.As the largest NW-trend active fault in Beijing area,the Nankou-Sunhe fault plays an important role in earthquake disaster and city construction.In this study,we collect continuous ambient noise data recorded by 43 temporary short-period seismograph between September 21th to October 12th 2019 to investigate the near-surface structure beneath the Nankou-Sunhe fault by using ambient noise tomography(ANT)and horizontal-to-vertical spectral ratio(HVSR)method.From ambient noise processing,fundamental-mode Rayleigh wave signals are clearly observed in the frequency band of 0.4-2.5 Hz.Then direct surface-wave inversion algorithm is applied to calculate the 3D shear-wave velocity model.Our results show that there is a sharp velocity contrast across the Nankou-Sunhe fault,with low velocities down to about 2 km on the hanging wall and high velocity on the footwall of the fault.According to the geological investigation,the low velocities are related to thicker sediments and Jurassic volcanic rock below which are the cap rock of the hydrothermal system.From the HVSR analysis,the HVSR curves of the sites near the fault shows double-peak,one less than 1 Hz and the other centered 7 Hz.After converting frequency to depth by the empirical equation,the results show that the thickness of sediments is thinned from southwest to northeast,which generally agrees well to field survey.Our results provide high-resolution near-surface structure for future study on disaster risk reduction and urban planning.
