Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is...Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.展开更多
A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnel...A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.展开更多
In some oilfields with 3D seismic data, the deeper structure cannot be observed due to poor quality deep seismic data. Layer stripping using both seismic and gravity data is a solution for this problem but it cannot g...In some oilfields with 3D seismic data, the deeper structure cannot be observed due to poor quality deep seismic data. Layer stripping using both seismic and gravity data is a solution for this problem but it cannot get satisfactory results because the horizontal variations in formation density are ignored. We present a variable-density formation separation technique to address this problem. Based on 3D seismic depth data and laterallyvariable density derived from 3D seismic velocity data, the upper formation gravity effect is calculated by forward modeling and removed from the Bouguer gravity. The formation-separated gravity anomaly with variable density is obtained, which mainly reflects the deeper geological structure. In block XX of North Africa, the shallow formations seismic data is excellent but the data at the top of basement is poor. The formation-separated gravity anomaly processed under the control of 3D seismic data fits well with the known seismic interpretation and wells. It makes the geological interpretation more reliable.展开更多
An intensive earthquake, the Wenchuan Earthquake of 8.0 on the Richter scale, struck western Sichuan, China on May 12, 2008. The earthquake has tremendously affected all industries in the quake-hit areas, with no exce...An intensive earthquake, the Wenchuan Earthquake of 8.0 on the Richter scale, struck western Sichuan, China on May 12, 2008. The earthquake has tremendously affected all industries in the quake-hit areas, with no exception of the local tourism. The study of the effect of the earthquake on tourism enriches the theory of tourism, and more importantly, it well serves as the foundation for policy making. The objective of this study is to outline for readers the empirical findings on the various ways that the earthquake affected the operations and viability of tourism in the quake-hit areas. This paper is mainly divided into 3 parts. The first part is to discuss the importance of tourism in the quake-hit areas. The second is to analyze the influencing factors of tourism. The third is to assess the impact of the earthquake on tourism in Sichuan in different seasons.展开更多
For the purpose of investigating conditions of earthquake pregnancies,a heterogeneous 2-D single fault model with 81 × 81 cells is set up. By using cellular automata models and changing the model heterogeneity an...For the purpose of investigating conditions of earthquake pregnancies,a heterogeneous 2-D single fault model with 81 × 81 cells is set up. By using cellular automata models and changing the model heterogeneity and correlation parameters, we compute and get different synthetic event catalogues for analyzing general seismic activity and intensity distribution properties. The results show that different heterogeneous structures produce different seismic sequence types and G-R relationship,so the heterogeneity is an important influencing factor on seismicity. Nevertheless,both the coefficients of stress redistribution and local friction loss can also influence seismicity to some extent. This is possibly useful for further understanding of the complexity of earthquake processes.展开更多
On April 14, 2010 at 07：49 （Beijing time）, a catastrophic earthquake with Ms 7. 1 occurred at the central Qinghai-Tibetan Plateau. The epicenter was located at Yushu county, Qinghai Province, China. A total of 2036...On April 14, 2010 at 07：49 （Beijing time）, a catastrophic earthquake with Ms 7. 1 occurred at the central Qinghai-Tibetan Plateau. The epicenter was located at Yushu county, Qinghai Province, China. A total of 2036 landslides were determined from visual interpretation of aerial photographs and high resolution remote sensing images, and verified by selected field investigations. These landslides covered a total area of about 1. 194km~. Characteristics and failure mechanisms of these landslides are listed in this paper, including the fact that the spatial distribution of these landslides is controlled by co- seismic main surface fault ruptures. Most of the landslides were small scale, causing rather less hazards, and often occurring close to each other. The landslides were of various types, including mainly disrupted landslides and rock falls in shallows and also deep-seated landslides, liquefaction induced landslides, and compound landslides. In addition to strong ground shaking, which is the direct landslide triggering factor, geological, topographical, and human activity also have impact on the occurrence of earthquake triggered landslides. In this paper, five types of failure mechanisms related to the landslides are presented, namely, the excavated toes of slopes accompanied by strong ground shaking; surface water infiltration accompanied by strong ground shaking; co- seismic fault slipping accompanied by strong ground shaking; only strong ground shaking; and delayed occurrence of landslides due to snow melt or rainfall infiltration at sites where slopes were weakened by co-seismic ground shaking. Besides the main co-seismic surface ruptures, slope fissures were also delineated from visual interpretation of aerial photographs in high resolution. A total of 4814 slope fissures, with a total length up to 77. lkm, were finally mapped. These slope fissures are mainly distributed on the slopes located at the southeastern end of the main co-seismic surface rupture zone, an area subject to strong compression during the earthquake.展开更多
The Quality factor is the parameter that can be used to describe the energy attenuation on seismic wave. In theory, we can obtain the relationship between the change of the coda wave quality factor with time and the s...The Quality factor is the parameter that can be used to describe the energy attenuation on seismic wave. In theory, we can obtain the relationship between the change of the coda wave quality factor with time and the strong earthquake preparation process on the basis of the quality factor of a coda wave in a same ray path. However, in reality the coda wave quality factor measured by different seismic coda waves corresponds to different seismic wave ray paths. The change of the quality factor with time is related to non-elastic characteristics of the medium and the volume of scattering ellipsoid constrained by scattered wave phase fronts, besides the change of regional stress field. This paper discusses the relationship between quality factor, epicenter distance and different lapse time, and then discusses the relationship between quality factor and frequency. Furthermore the determination method of the coda wave quality factor is put forward. The improved determination method of the quality factor, which removes the influence of different earthquakes or propagation depth of scattered waves, may increase measurement precision, thus information pertaining to abnormal changes in quality factor and the relationship between the quality factor and earthquake preparation process can be acquired.展开更多
Forty-eight interviews were undertaken with residents in Timaru, Wanganui and Napier, New Zealand, in 2008 to explore how people understand and use information about earthquake hazards and preparedness, and how this p...Forty-eight interviews were undertaken with residents in Timaru, Wanganui and Napier, New Zealand, in 2008 to explore how people understand and use information about earthquake hazards and preparedness, and how this process affects actual preparedness. Three main types of information were identified as being utilized by people： passive information （e.g., newspapers, brochures, TV, radio, websites）, interactive information （e.g., community activities, school activities~ and workplace activities）, and experiential information （e.g., experiencing a hazardous event, responding to an event, and working in an organization that deals with hazards）. People tended to either contextualize hazard and preparedness information around any prevailing beliefs they had or form new beliefs on exposure to information. A number of core beliefs were identified as crucial for helping people consider that preparing is important and motivating actual adjustment adoption. Society also has an influence on how people interpret information and form intentions to prepare. People are often influenced by the opinions of others, and as preparing for disasters is not seen as a societal norm, this can cause people not to prepare. Feeling a responsibility for others （e.g., children） appears to be a major driver of preparedness. Other societal factors such as trust, leadership and sense of community also influence interpretation, dissemination and use of hazards and preparedness information. Finally, a number of resource issues can help or hinder preparedness.展开更多
文摘Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.
基金supported by the National Natural Science Foundation of China (51678438 & 51308574 & 51478343 & 41672289)the National Basic Research Program of China (2015CB057902)+2 种基金the Shanghai Educational Development Foundation (13CG17)the Shanghai Committee of Science and Technology (13231200503 & 16DZ1200302 & 16DZ1201904)the support from the Fundamental Research Funds for the Central Universities
文摘A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.
文摘In some oilfields with 3D seismic data, the deeper structure cannot be observed due to poor quality deep seismic data. Layer stripping using both seismic and gravity data is a solution for this problem but it cannot get satisfactory results because the horizontal variations in formation density are ignored. We present a variable-density formation separation technique to address this problem. Based on 3D seismic depth data and laterallyvariable density derived from 3D seismic velocity data, the upper formation gravity effect is calculated by forward modeling and removed from the Bouguer gravity. The formation-separated gravity anomaly with variable density is obtained, which mainly reflects the deeper geological structure. In block XX of North Africa, the shallow formations seismic data is excellent but the data at the top of basement is poor. The formation-separated gravity anomaly processed under the control of 3D seismic data fits well with the known seismic interpretation and wells. It makes the geological interpretation more reliable.
基金the Second Phase of the CAS Action-plan for West Development(KZCX2-XB2-02-03-02)the National Science and Technology Supporting Program in the Eleventh Five-year Plan(No.2006BACo1A11)
文摘An intensive earthquake, the Wenchuan Earthquake of 8.0 on the Richter scale, struck western Sichuan, China on May 12, 2008. The earthquake has tremendously affected all industries in the quake-hit areas, with no exception of the local tourism. The study of the effect of the earthquake on tourism enriches the theory of tourism, and more importantly, it well serves as the foundation for policy making. The objective of this study is to outline for readers the empirical findings on the various ways that the earthquake affected the operations and viability of tourism in the quake-hit areas. This paper is mainly divided into 3 parts. The first part is to discuss the importance of tourism in the quake-hit areas. The second is to analyze the influencing factors of tourism. The third is to assess the impact of the earthquake on tourism in Sichuan in different seasons.
基金funded by the National Natural Science Foundation of China ( Grant No. 40774015)
文摘For the purpose of investigating conditions of earthquake pregnancies,a heterogeneous 2-D single fault model with 81 × 81 cells is set up. By using cellular automata models and changing the model heterogeneity and correlation parameters, we compute and get different synthetic event catalogues for analyzing general seismic activity and intensity distribution properties. The results show that different heterogeneous structures produce different seismic sequence types and G-R relationship,so the heterogeneity is an important influencing factor on seismicity. Nevertheless,both the coefficients of stress redistribution and local friction loss can also influence seismicity to some extent. This is possibly useful for further understanding of the complexity of earthquake processes.
基金sponsored by the National Natural Science Foundation,China(40821160550),supported by the National Natural Science Foundation of China (41202235 )the Basic Scientific Fund of the Institute of Geology, China Earthquake Administration (IGCEA1215)
文摘On April 14, 2010 at 07：49 （Beijing time）, a catastrophic earthquake with Ms 7. 1 occurred at the central Qinghai-Tibetan Plateau. The epicenter was located at Yushu county, Qinghai Province, China. A total of 2036 landslides were determined from visual interpretation of aerial photographs and high resolution remote sensing images, and verified by selected field investigations. These landslides covered a total area of about 1. 194km~. Characteristics and failure mechanisms of these landslides are listed in this paper, including the fact that the spatial distribution of these landslides is controlled by co- seismic main surface fault ruptures. Most of the landslides were small scale, causing rather less hazards, and often occurring close to each other. The landslides were of various types, including mainly disrupted landslides and rock falls in shallows and also deep-seated landslides, liquefaction induced landslides, and compound landslides. In addition to strong ground shaking, which is the direct landslide triggering factor, geological, topographical, and human activity also have impact on the occurrence of earthquake triggered landslides. In this paper, five types of failure mechanisms related to the landslides are presented, namely, the excavated toes of slopes accompanied by strong ground shaking; surface water infiltration accompanied by strong ground shaking; co- seismic fault slipping accompanied by strong ground shaking; only strong ground shaking; and delayed occurrence of landslides due to snow melt or rainfall infiltration at sites where slopes were weakened by co-seismic ground shaking. Besides the main co-seismic surface ruptures, slope fissures were also delineated from visual interpretation of aerial photographs in high resolution. A total of 4814 slope fissures, with a total length up to 77. lkm, were finally mapped. These slope fissures are mainly distributed on the slopes located at the southeastern end of the main co-seismic surface rupture zone, an area subject to strong compression during the earthquake.
基金sponsored by the Natural Science Foundation of Shandong Province (Y2007E09)Joint Earthquake Science Foundation (C08028)Special Application Research of Digital Seismic Wave Data ,Shangdong,China
文摘The Quality factor is the parameter that can be used to describe the energy attenuation on seismic wave. In theory, we can obtain the relationship between the change of the coda wave quality factor with time and the strong earthquake preparation process on the basis of the quality factor of a coda wave in a same ray path. However, in reality the coda wave quality factor measured by different seismic coda waves corresponds to different seismic wave ray paths. The change of the quality factor with time is related to non-elastic characteristics of the medium and the volume of scattering ellipsoid constrained by scattered wave phase fronts, besides the change of regional stress field. This paper discusses the relationship between quality factor, epicenter distance and different lapse time, and then discusses the relationship between quality factor and frequency. Furthermore the determination method of the coda wave quality factor is put forward. The improved determination method of the quality factor, which removes the influence of different earthquakes or propagation depth of scattered waves, may increase measurement precision, thus information pertaining to abnormal changes in quality factor and the relationship between the quality factor and earthquake preparation process can be acquired.
文摘Forty-eight interviews were undertaken with residents in Timaru, Wanganui and Napier, New Zealand, in 2008 to explore how people understand and use information about earthquake hazards and preparedness, and how this process affects actual preparedness. Three main types of information were identified as being utilized by people： passive information （e.g., newspapers, brochures, TV, radio, websites）, interactive information （e.g., community activities, school activities~ and workplace activities）, and experiential information （e.g., experiencing a hazardous event, responding to an event, and working in an organization that deals with hazards）. People tended to either contextualize hazard and preparedness information around any prevailing beliefs they had or form new beliefs on exposure to information. A number of core beliefs were identified as crucial for helping people consider that preparing is important and motivating actual adjustment adoption. Society also has an influence on how people interpret information and form intentions to prepare. People are often influenced by the opinions of others, and as preparing for disasters is not seen as a societal norm, this can cause people not to prepare. Feeling a responsibility for others （e.g., children） appears to be a major driver of preparedness. Other societal factors such as trust, leadership and sense of community also influence interpretation, dissemination and use of hazards and preparedness information. Finally, a number of resource issues can help or hinder preparedness.
