In this paper,statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal M_S8. 1 earthquake,and the co-seismic response characteristics of the water level and water temperature are ana...In this paper,statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal M_S8. 1 earthquake,and the co-seismic response characteristics of the water level and water temperature are analyzed and summarized with the digital data. The results show that the Nepal M_S8. 1 earthquake had greater impact on the Yunnan region,and the macro and micro dynamics of fluids showed significant co-seismic response. The earthquake recording capacity of water level and temperature measurement is significantly higher than that of water radon and water quality to this large earthquake; the maximum amplitude and duration of co-seismic response of water level and water temperature vary greatly in different wells. The changing forms are dominated by fluctuation and step rise in water level,and a rising or falling restoration in water temperature. From the records of the main shock and the maximum strong aftershock,we can see that the greater magnitude of earthquake,the higher ratio of the occurrence of co-seismic response,and in the same well,the larger the response amplitude,as well as the longer the duration. The amplitude and duration of co-seismic response recorded by different instruments in a same well are different. Water temperature co-seismic response almost occurred in wells with water level response,indicating that the well water level and water temperature are closely related in co-seismic response,and the well water temperature seismic response was caused mainly by well water level seismic response.展开更多
We analyzed 223 earthquakes with M ≥5. 0 that occurred in the Yunnan region during1965- 2014,among which 74( about 33. 2%) had foreshocks. There are great differences in foreshock populations in different tectonic bl...We analyzed 223 earthquakes with M ≥5. 0 that occurred in the Yunnan region during1965- 2014,among which 74( about 33. 2%) had foreshocks. There are great differences in foreshock populations in different tectonic blocks: the most abundant foreshocks occurred in the Lancang-Gengma and Tengchong-Baoshan blocks,which have the most abundant foreshocks in the Yunnan region. The predominant magnitude difference,time interval and spatial distance are 0. 5- 2. 9,within 10 days and within 20 km,respectively.These characteristics can be used to forecast the mainshock after the identification of a foreshock.展开更多
Source spectra for moderate and small earthquakes are obtained after removing the path effect,site effect,and instrument response,etc. in the observed S-wave spectra. Based on the Brune source model and by means of ge...Source spectra for moderate and small earthquakes are obtained after removing the path effect,site effect,and instrument response,etc. in the observed S-wave spectra. Based on the Brune source model and by means of genetic algorithm, the source parameters including seismic moment, stress drop, source dimension, etc. are determined, the radiated seismic energy for small-to-moderate earthquakes is measured with consideration of underestimation and compensation brought forth by limited bandwidth of the instrument,and the scaling relationships of static and dynamic parameters for earthquakes with M_L 2. 0 ～ 5. 3 in the Yunnan region are analyzed. The results show that the seismic moment is between 2. 1 × 10^(12) N·m and 1. 2 × 10^(16) N·m,and there is a linear relation of lgM_0 = 1. 01M_L + 10. 59 between the seismic moment and local magnitude. The source dimension varies from 86. 9m to 1220. 4m. The seismic moment and rupture radius remain a linear correlation of lgM_0 = 0. 003a + 12. 90. The stress drop is in the range of 0. 03 ～ 57. 55MPa,and increases with seismic moment for M_0 < 4 × 10^(14) N·m,but it doesn't vary with seismic moment for M_0 > 4 × 10^(14) N·m. The seismic moment shows dependency of corner frequency. Assuming a constant stress drop,we can obtain the relationship of lgf_c = - 1/3 lgM_0 + 5. 32 between the seismic moment and corner frequency using least squares fitting. The theoretical radiated seismic energy is between 3. 01 × 10~6 J and 2. 06 × 10^(12) J. The linear relationship between the radiated seismic energy and local magnitude is lgE_R = 1. 18M_L + 5. 69. The scaled energy increases with seismic moment for M_0 < 4 × 10^(14) N·m,however it doesn't seem to vary with seismic moment for M_0 > 4 × 10^(14) N·m. The apparent stress is in the range of 0. 02 ～ 31. 4 MPa,and also seems independent of seismic depth.展开更多
The reason for the failure to forecast the Wenchuan M_S8.0 earthquake is under study, based on the systematically collection of the seismicity anomalies and their analysis results from annual earthquake tendency forec...The reason for the failure to forecast the Wenchuan M_S8.0 earthquake is under study, based on the systematically collection of the seismicity anomalies and their analysis results from annual earthquake tendency forecasts between the 2001 Western Kunlun Mountains Pass M_S8.1 earthquake and the 2008 Wenchuan M_S8.0 earthquake. The results show that the earthquake tendency estimation of Chinese Mainland is for strong earthquakes to occur in the active stage, and that there is still potential for the occurrence of a M_S8.0 large earthquake in Chinese Mainland after the 2001 Western Kunlun Mountains Pass earthquake. However the phenomena that many large earthquakes occurred around Chinese Mainland, and the 6-year long quietude of M_S7.0 earthquake and an obvious quietude of M_S5.0 and M_S6.0 earthquakes during 2002～2007 led to the distinctly lower forecast estimation of earthquake tendency in Chinese Mainland after 2006. The middle part in the north-south seismic belt has been designated a seismic risk area of strong earthquake in recent years, but, the estimation of the risk degree in Southwestern China is insufficient after the Ning’er M_S6.4 earthquake in Yunnan in 2007. There are no records of earthquakes with M_S≥7.0 in the Longmenshan fault, which is one of reasons that this fault was not considered a seismic risk area of strong earthquakes in recent years.展开更多
基金sponsored by the special fund of“A Study on Short-term Seismic Tracking of Strong Earthquakes in the Yunnan Area”of the“Ten Key Projects”in Yunnan Provincethe 2016 Earthquake Trend Tracking Task of China Earthquake Administration(2016010305)the 2015 Earthquake Trend Tracking Task of Earthquake Administration of Yunnan Province
文摘In this paper,statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal M_S8. 1 earthquake,and the co-seismic response characteristics of the water level and water temperature are analyzed and summarized with the digital data. The results show that the Nepal M_S8. 1 earthquake had greater impact on the Yunnan region,and the macro and micro dynamics of fluids showed significant co-seismic response. The earthquake recording capacity of water level and temperature measurement is significantly higher than that of water radon and water quality to this large earthquake; the maximum amplitude and duration of co-seismic response of water level and water temperature vary greatly in different wells. The changing forms are dominated by fluctuation and step rise in water level,and a rising or falling restoration in water temperature. From the records of the main shock and the maximum strong aftershock,we can see that the greater magnitude of earthquake,the higher ratio of the occurrence of co-seismic response,and in the same well,the larger the response amplitude,as well as the longer the duration. The amplitude and duration of co-seismic response recorded by different instruments in a same well are different. Water temperature co-seismic response almost occurred in wells with water level response,indicating that the well water level and water temperature are closely related in co-seismic response,and the well water temperature seismic response was caused mainly by well water level seismic response.
基金funded by the Database Establishment of Foreshocks before the M_W≥6.0 Earthquakes Worldwidethe Science and Technology Project of the Earthquake Administration of Yunnan Province
文摘We analyzed 223 earthquakes with M ≥5. 0 that occurred in the Yunnan region during1965- 2014,among which 74( about 33. 2%) had foreshocks. There are great differences in foreshock populations in different tectonic blocks: the most abundant foreshocks occurred in the Lancang-Gengma and Tengchong-Baoshan blocks,which have the most abundant foreshocks in the Yunnan region. The predominant magnitude difference,time interval and spatial distance are 0. 5- 2. 9,within 10 days and within 20 km,respectively.These characteristics can be used to forecast the mainshock after the identification of a foreshock.
基金funded jointly by the Key Applied and Fundamental Research Project of Yunnan Province (2010CC006)the Key Project of Yunnan Province (JCYB-20080601-4)the Joint Earthquake Science Foundation of China (C08065)
文摘Source spectra for moderate and small earthquakes are obtained after removing the path effect,site effect,and instrument response,etc. in the observed S-wave spectra. Based on the Brune source model and by means of genetic algorithm, the source parameters including seismic moment, stress drop, source dimension, etc. are determined, the radiated seismic energy for small-to-moderate earthquakes is measured with consideration of underestimation and compensation brought forth by limited bandwidth of the instrument,and the scaling relationships of static and dynamic parameters for earthquakes with M_L 2. 0 ～ 5. 3 in the Yunnan region are analyzed. The results show that the seismic moment is between 2. 1 × 10^(12) N·m and 1. 2 × 10^(16) N·m,and there is a linear relation of lgM_0 = 1. 01M_L + 10. 59 between the seismic moment and local magnitude. The source dimension varies from 86. 9m to 1220. 4m. The seismic moment and rupture radius remain a linear correlation of lgM_0 = 0. 003a + 12. 90. The stress drop is in the range of 0. 03 ～ 57. 55MPa,and increases with seismic moment for M_0 < 4 × 10^(14) N·m,but it doesn't vary with seismic moment for M_0 > 4 × 10^(14) N·m. The seismic moment shows dependency of corner frequency. Assuming a constant stress drop,we can obtain the relationship of lgf_c = - 1/3 lgM_0 + 5. 32 between the seismic moment and corner frequency using least squares fitting. The theoretical radiated seismic energy is between 3. 01 × 10~6 J and 2. 06 × 10^(12) J. The linear relationship between the radiated seismic energy and local magnitude is lgE_R = 1. 18M_L + 5. 69. The scaled energy increases with seismic moment for M_0 < 4 × 10^(14) N·m,however it doesn't seem to vary with seismic moment for M_0 > 4 × 10^(14) N·m. The apparent stress is in the range of 0. 02 ～ 31. 4 MPa,and also seems independent of seismic depth.
基金the State Science and Technology Programof Tackle Key Problemfor the tenth "Five-Year Plan" of China (2004BA601B01-04-03) and the Youth Fund of Earthquake Administration of Yunnan Province ,China
基金sponsored by the Key Project of Chinese National Programs for Fundamental Research and Development (973 program) (2004CB418406)the State Science and Technology Program of Tackle Key Problem(2006BAC01B02-01-04),China
文摘The reason for the failure to forecast the Wenchuan M_S8.0 earthquake is under study, based on the systematically collection of the seismicity anomalies and their analysis results from annual earthquake tendency forecasts between the 2001 Western Kunlun Mountains Pass M_S8.1 earthquake and the 2008 Wenchuan M_S8.0 earthquake. The results show that the earthquake tendency estimation of Chinese Mainland is for strong earthquakes to occur in the active stage, and that there is still potential for the occurrence of a M_S8.0 large earthquake in Chinese Mainland after the 2001 Western Kunlun Mountains Pass earthquake. However the phenomena that many large earthquakes occurred around Chinese Mainland, and the 6-year long quietude of M_S7.0 earthquake and an obvious quietude of M_S5.0 and M_S6.0 earthquakes during 2002～2007 led to the distinctly lower forecast estimation of earthquake tendency in Chinese Mainland after 2006. The middle part in the north-south seismic belt has been designated a seismic risk area of strong earthquake in recent years, but, the estimation of the risk degree in Southwestern China is insufficient after the Ning’er M_S6.4 earthquake in Yunnan in 2007. There are no records of earthquakes with M_S≥7.0 in the Longmenshan fault, which is one of reasons that this fault was not considered a seismic risk area of strong earthquakes in recent years.
