Following the Chichi Earthquake （ML=7.3） in 1999, sediment-related disasters, such as landslides and debris flows, have become more frequent in Taiwan. Because engineering structures cannot be fully and rapidly empl...Following the Chichi Earthquake （ML=7.3） in 1999, sediment-related disasters, such as landslides and debris flows, have become more frequent in Taiwan. Because engineering structures cannot be fully and rapidly emplaeed, the government has initiated non-structural hazard mitigation programs. Initially, community debris flow evacuation drills were promoted in 2000. Typhoon Toraji caused numerous debris flow events in July 2001, and some communities evacuated according to the drills, significantly reducing the numbers of possible casualties. Based on that result, the government expanded the program for evacuation drills. Secondly, the early warning system created after the Chichi Earthquake will prevent many potential future casualties. Rainfall threshold values for debris flow warnings in different areas are determined from information received from local weather stations and modified for local geomorphologic situations. Real- time information is gradually being integrated to create a debris flow disaster warning system, the goal of which is to provide warnings to zones in which debris flows are likely. The warning system was launched in 2005 and has two levels of alarms： yellow and red. The final, red alarm triggers enforced evacuation. Overall, the decrease in casualties from debris flows during the decade after the Chichi Earthquake is not the result of a decrease in number or severity of sediment related disasters, but is more directly related to the gradually improved early warning and evacuation system. However, the compound hazards resulting from Typhoon Morakotin 2009 remind us of the ongoing need for improving the existing mitigation system.展开更多
The study found that strong magnetic anomalies repeatedly took place before big earthquakes. Based on geomagnetic record analysis results,we discussed a possible pattern of the magnetic anomalies prior to earthquake. ...The study found that strong magnetic anomalies repeatedly took place before big earthquakes. Based on geomagnetic record analysis results,we discussed a possible pattern of the magnetic anomalies prior to earthquake. In meizoseismal area or epicenter,in a time period of 36 h to about 10 min before earthquake,the exceptional big geomagnetic change increases with the magnitude of earthquake. We calculated that,in a place of 1 km from the epicenter,the magnetic anomaly before destructive earthquakes of Ms 6～9 can reach to 102～104 nT(the magnitude of earth magnetic field is 104 nT) ,rather than the magnitude of 10 nT from seismomagnetic effect theories since 1960s. From this we speculated the abnormal magnetic ULF near epicenter before earthquake seems to be an "intermittent magnetic eruption". Accordingly,we proposed that geomagnetic induction earthquake alarm can be a new pre-warning method to surmount hardship in solving the puzzledom of earthquake imminent prediction.展开更多
The Tancheng-Lujiang fault zone has great influence in eastern China. Studies have shown obvious signs of neotectonic activities on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone. In this study,on the basis...The Tancheng-Lujiang fault zone has great influence in eastern China. Studies have shown obvious signs of neotectonic activities on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone. In this study,on the basis of the previous work,many seismological surveys are made along the Tancheng-Lujiang fault zone and trenches are excavated in key sites.Combined with the analysis of the seismic activities along the fault,the fault movement features and future seismic risk are discussed. Much first-hand information obtained in the paper can provide an important reference value for the study of large earthquake recurrence rules and the mid and long-term earthquake prediction on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone.展开更多
Through analysis of natural and social attributes of earthquake forecasting,the relationship between the natural and social attributes of earthquake forecasting(early warning)has been discussed.Regarding the natural a...Through analysis of natural and social attributes of earthquake forecasting,the relationship between the natural and social attributes of earthquake forecasting(early warning)has been discussed.Regarding the natural attributes of earthquake forecasting,it only attempts to forecast the magnitude,location and occurrence time of future earthquake based on the analysis of observational data and relevant theories and taking into consideration the present understanding of seismogeny and earthquake generation.It need not consider the consequences an earthquake forecast involves,and its purpose is to check out the level of scientific understanding of earthquakes.In respect of the social aspect of earthquake forecasting,people also focus on the consequence that the forecasting involves,in addition to its natural aspect,such as the uncertainty of earthquake prediction itself,the impact of earthquake prediction,and the earthquake resistant capability of structures(buildings),lifeline works,etc.In a word,it highlights the risk of earthquake forecasting and tries to mitigate the earthquake hazard as much as possible.In this paper,the authors also discuss the scientific and social challenges faced in earthquake prediction and analyze preliminarily the meanings and content of earthquake early warning.展开更多
By scanning modulated or un-modulated earthquakes spatio-temporally in the region of Sichuan-Yunnan,short-term non-stationary seismic precursory patterns were extracted with significant difference and the characterist...By scanning modulated or un-modulated earthquakes spatio-temporally in the region of Sichuan-Yunnan,short-term non-stationary seismic precursory patterns were extracted with significant difference and the characteristic of non-stationary short-term seismic anomalies were analyzed as well as prediction efficiency of modulated small earthquakes before a strong earthquake. Besides,small earthquake modulation ratios near the region of the epicenter were calculated and sorted by time. The results indicated that there were significant effects using the modulated earthquake method to predict earthquakes greater than MS6. 0 in a short time. Before the MS8. 0 Wenchuan earthquake,there were obvious short-term precursory seismicity gap patterns of modulated small earthquakes.展开更多
Although seismic gap theory plays an important role in the med-and long-term earthquake prediction,the potential risk of the non-seismic gap in historical earthquake rupture areas will need to be simultaneously taken ...Although seismic gap theory plays an important role in the med-and long-term earthquake prediction,the potential risk of the non-seismic gap in historical earthquake rupture areas will need to be simultaneously taken into account in the study of med-and long-term earthquake prediction,due to the temporally clustering or non-linear behavior of large earthquake recurrence.In order to explore technical methods which can be based on observational data,and identify historical earthquake rupture zones( including the seismic gap in historical and prehistoric earthquake rupture zones),we select eight historical large earthquake rupture zones with different elapsed times on the mid-north segment of the North-South Seismic Belt to make quantitative analysis on the characteristics of modern seismicity of these zones and preliminarily explore the seismicity method for determining the urgency degree of potential earthquake hazards.The results mainly show that the pvalue,which reflects the attenuation of earthquake sequence,and the a-value,which reflects the seismicity rate,are strongly related to the elapsed time of the latest earthquake in the rupture zone.However,the corresponding relationships in some rupture areas are not clear perhaps due to the complex fault structure and faulting behavior.The b-value,which represents the state of tectonic stress accumulation,does not easily reflect the elapsed time information of different evolution stages.The b-value temporal scanning shows a steady evolution over time in most of the rupture zones,but in the rupture zone of the Wudu M8.0 earthquake of 1879,the b-value shows significant fluctuations with a decreasing trend for 20 years.By comparative analysis,we conclude that the rupture zones of the 1933 M7.5 Maoxian earthquake and the 1976 M7.2 Songpan-Pingwu earthquake are still in the decaying period of earthquake sequences,and thus do not have the background for recurrence of M7.0 earthquakes.The low b-value Maqu segment,which is located at the north margin of the rupture zone of the 842A.D.M7.0 Diebu earthquake,is more dangerous than the Diebu segment.The continuous decline of the b-value in the 1879 M8.0 Wudu earthquake rupture zone may also indicate a new round of seismogenic process.展开更多
In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10...In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10 years in America. Also,we give a brief introduction of Earthquake Early Warning( EEW) in China,and based on the summary of EEW in California we make an analysis of the perspectives,misconceptions,and challenges that China may have.展开更多
基金supported by the Soil and Water Conservation Bureau,Council of Agriculture,and National Basic Research Program of China (2008CB425802)
文摘Following the Chichi Earthquake （ML=7.3） in 1999, sediment-related disasters, such as landslides and debris flows, have become more frequent in Taiwan. Because engineering structures cannot be fully and rapidly emplaeed, the government has initiated non-structural hazard mitigation programs. Initially, community debris flow evacuation drills were promoted in 2000. Typhoon Toraji caused numerous debris flow events in July 2001, and some communities evacuated according to the drills, significantly reducing the numbers of possible casualties. Based on that result, the government expanded the program for evacuation drills. Secondly, the early warning system created after the Chichi Earthquake will prevent many potential future casualties. Rainfall threshold values for debris flow warnings in different areas are determined from information received from local weather stations and modified for local geomorphologic situations. Real- time information is gradually being integrated to create a debris flow disaster warning system, the goal of which is to provide warnings to zones in which debris flows are likely. The warning system was launched in 2005 and has two levels of alarms： yellow and red. The final, red alarm triggers enforced evacuation. Overall, the decrease in casualties from debris flows during the decade after the Chichi Earthquake is not the result of a decrease in number or severity of sediment related disasters, but is more directly related to the gradually improved early warning and evacuation system. However, the compound hazards resulting from Typhoon Morakotin 2009 remind us of the ongoing need for improving the existing mitigation system.
文摘The study found that strong magnetic anomalies repeatedly took place before big earthquakes. Based on geomagnetic record analysis results,we discussed a possible pattern of the magnetic anomalies prior to earthquake. In meizoseismal area or epicenter,in a time period of 36 h to about 10 min before earthquake,the exceptional big geomagnetic change increases with the magnitude of earthquake. We calculated that,in a place of 1 km from the epicenter,the magnetic anomaly before destructive earthquakes of Ms 6～9 can reach to 102～104 nT(the magnitude of earth magnetic field is 104 nT) ,rather than the magnitude of 10 nT from seismomagnetic effect theories since 1960s. From this we speculated the abnormal magnetic ULF near epicenter before earthquake seems to be an "intermittent magnetic eruption". Accordingly,we proposed that geomagnetic induction earthquake alarm can be a new pre-warning method to surmount hardship in solving the puzzledom of earthquake imminent prediction.
基金jointly sponsored by the Special Fund for Earthquake-related Scientific Research of China Earthquake Administration(201308012)the Anhui Provincial Natural Science Foundation(10040606Q24),China
文摘The Tancheng-Lujiang fault zone has great influence in eastern China. Studies have shown obvious signs of neotectonic activities on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone. In this study,on the basis of the previous work,many seismological surveys are made along the Tancheng-Lujiang fault zone and trenches are excavated in key sites.Combined with the analysis of the seismic activities along the fault,the fault movement features and future seismic risk are discussed. Much first-hand information obtained in the paper can provide an important reference value for the study of large earthquake recurrence rules and the mid and long-term earthquake prediction on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone.
基金supported by the Subject of the National Key Technology R & D Program for the 11th "Five-Year Plan"(2006BAC01B03-02-03),China
文摘Through analysis of natural and social attributes of earthquake forecasting,the relationship between the natural and social attributes of earthquake forecasting(early warning)has been discussed.Regarding the natural attributes of earthquake forecasting,it only attempts to forecast the magnitude,location and occurrence time of future earthquake based on the analysis of observational data and relevant theories and taking into consideration the present understanding of seismogeny and earthquake generation.It need not consider the consequences an earthquake forecast involves,and its purpose is to check out the level of scientific understanding of earthquakes.In respect of the social aspect of earthquake forecasting,people also focus on the consequence that the forecasting involves,in addition to its natural aspect,such as the uncertainty of earthquake prediction itself,the impact of earthquake prediction,and the earthquake resistant capability of structures(buildings),lifeline works,etc.In a word,it highlights the risk of earthquake forecasting and tries to mitigate the earthquake hazard as much as possible.In this paper,the authors also discuss the scientific and social challenges faced in earthquake prediction and analyze preliminarily the meanings and content of earthquake early warning.
基金supported by the National Basic ResearchProgram (973 Program),entitled Global deep geophysical field and the relation between its geodynamic effect and Wenchuan Earthquake
文摘By scanning modulated or un-modulated earthquakes spatio-temporally in the region of Sichuan-Yunnan,short-term non-stationary seismic precursory patterns were extracted with significant difference and the characteristic of non-stationary short-term seismic anomalies were analyzed as well as prediction efficiency of modulated small earthquakes before a strong earthquake. Besides,small earthquake modulation ratios near the region of the epicenter were calculated and sorted by time. The results indicated that there were significant effects using the modulated earthquake method to predict earthquakes greater than MS6. 0 in a short time. Before the MS8. 0 Wenchuan earthquake,there were obvious short-term precursory seismicity gap patterns of modulated small earthquakes.
基金funded jointly by National Science&Technology Pillar Program,China(Grant No.2012BAK19B01)the Task-oriented Contract for Seismic Regime Monitoring(2010020304)
文摘Although seismic gap theory plays an important role in the med-and long-term earthquake prediction,the potential risk of the non-seismic gap in historical earthquake rupture areas will need to be simultaneously taken into account in the study of med-and long-term earthquake prediction,due to the temporally clustering or non-linear behavior of large earthquake recurrence.In order to explore technical methods which can be based on observational data,and identify historical earthquake rupture zones( including the seismic gap in historical and prehistoric earthquake rupture zones),we select eight historical large earthquake rupture zones with different elapsed times on the mid-north segment of the North-South Seismic Belt to make quantitative analysis on the characteristics of modern seismicity of these zones and preliminarily explore the seismicity method for determining the urgency degree of potential earthquake hazards.The results mainly show that the pvalue,which reflects the attenuation of earthquake sequence,and the a-value,which reflects the seismicity rate,are strongly related to the elapsed time of the latest earthquake in the rupture zone.However,the corresponding relationships in some rupture areas are not clear perhaps due to the complex fault structure and faulting behavior.The b-value,which represents the state of tectonic stress accumulation,does not easily reflect the elapsed time information of different evolution stages.The b-value temporal scanning shows a steady evolution over time in most of the rupture zones,but in the rupture zone of the Wudu M8.0 earthquake of 1879,the b-value shows significant fluctuations with a decreasing trend for 20 years.By comparative analysis,we conclude that the rupture zones of the 1933 M7.5 Maoxian earthquake and the 1976 M7.2 Songpan-Pingwu earthquake are still in the decaying period of earthquake sequences,and thus do not have the background for recurrence of M7.0 earthquakes.The low b-value Maqu segment,which is located at the north margin of the rupture zone of the 842A.D.M7.0 Diebu earthquake,is more dangerous than the Diebu segment.The continuous decline of the b-value in the 1879 M8.0 Wudu earthquake rupture zone may also indicate a new round of seismogenic process.
基金supported by the China Scholarship Council (CSC)China Earthquake Administration (CEA)+1 种基金Earthquake Administration of Hebei Provincepartially funded by the U. S. Geological Survey (USGS)
文摘In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10 years in America. Also,we give a brief introduction of Earthquake Early Warning( EEW) in China,and based on the summary of EEW in California we make an analysis of the perspectives,misconceptions,and challenges that China may have.
