To determine the studying region of China Testing Center of the Collaboratory for the Study of Earthquake Predictability (CSEP), we adopted the Entire-Magnitude-Range (EMR) method to study the spatial distribution of ...To determine the studying region of China Testing Center of the Collaboratory for the Study of Earthquake Predictability (CSEP), we adopted the Entire-Magnitude-Range (EMR) method to study the spatial distribution of minimum magnitude of completeness (MC) in the North-South Trending Seismic Belt (NSTSB) during the period from October 1, 2008 to May 31, 2011. Also bootstrap testing was performed to estimate the uncertainty of MC, i.e. δMC. The results show that MC (EMR)=1.6±0.03 for the whole region. From the spatial distributions of MC we find that MC is in the range of ML1.3～2.0 for most regions. Specifically, the spatial distribution of MC is consistent with the distribution of stations indicating high monitoring level in the southern part and low monitoring level in the northern part. Events located with less than three stations have great influence on Mc. Moreover, the uncertainty of minimum magnitude of completeness δMC ranges from 0.07 to 0.22. The spatial distribution of δMC agrees with the seismic rate. The shorter time span may cause larger δMC.展开更多
Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake fr...Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake from January 2010 to July 2014 and obtained the temporal and spatial variation of apparent stress before and after the Minxian earthquake. Results show that( 1) the high value of apparent stress of earthquakes with M_L≥4. 0 was concentrated in the epicenter area before the Minxian earthquake while that of earthquakes with M_L< 4. 0 was not;( 2) Apparent stress around the epicenter area showed an obvious increasing process before the Minxian earthquake and the increasing process has continued after the main shock,which means that this study area is still in the danger of strong earthquakes.展开更多
Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetr...Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetry Seismic Network in the Capital Circle Region of China and its surrounding areas from January 2002 to June 2006 by the Brune model.Relevant formulas that were used for the calculation of dynamic source parameters include rupture radius,seismic moment,seismic energy,stress drop,and apparent stress.Scaling relations and characteristics of temporal-spatial variations of these dynamic parameters before the MS5.1 Wenan earthquake in Hebei Province that occurred on July 20,2006 were analyzed.Results show that apparent stress,stress drop,and the ratio of seismic energy to the rupture radius had relatively high values in some areas before the Wenan earthquake.These high-value concentration areas were mainly distributed in the North China Plain seismic zone.As is seen from the time curves,parameters,such as apparent stress,stress drop,and ratio of seismic energy to rupture radius underwent significant ascending processes before the Wenan earthquake,but the variation in the corner frequency showed a descending trend.This result might be related to the enhancement of stress in the North China Plain seismic zone before the earthquake.展开更多
基金jointly sponsored by the Youth Fund Progamm of the National Natural Science Foundation of China ( 40804010 )the Central-level Basic Science Programm of Institute of Geophysics,CEA (DQJB10B23)
文摘To determine the studying region of China Testing Center of the Collaboratory for the Study of Earthquake Predictability (CSEP), we adopted the Entire-Magnitude-Range (EMR) method to study the spatial distribution of minimum magnitude of completeness (MC) in the North-South Trending Seismic Belt (NSTSB) during the period from October 1, 2008 to May 31, 2011. Also bootstrap testing was performed to estimate the uncertainty of MC, i.e. δMC. The results show that MC (EMR)=1.6±0.03 for the whole region. From the spatial distributions of MC we find that MC is in the range of ML1.3～2.0 for most regions. Specifically, the spatial distribution of MC is consistent with the distribution of stations indicating high monitoring level in the southern part and low monitoring level in the northern part. Events located with less than three stations have great influence on Mc. Moreover, the uncertainty of minimum magnitude of completeness δMC ranges from 0.07 to 0.22. The spatial distribution of δMC agrees with the seismic rate. The shorter time span may cause larger δMC.
基金sponsored by the regular project of earthquake monitoring and prediction in 2016(16C23ZX327)
文摘Based on the waveform data observed by the regional seismic network of Gansu Province,we calculated the apparent stress of 422 earthquakes with M_L≥ 2. 0 occurring in the surrounding area of the Minxian earthquake from January 2010 to July 2014 and obtained the temporal and spatial variation of apparent stress before and after the Minxian earthquake. Results show that( 1) the high value of apparent stress of earthquakes with M_L≥4. 0 was concentrated in the epicenter area before the Minxian earthquake while that of earthquakes with M_L< 4. 0 was not;( 2) Apparent stress around the epicenter area showed an obvious increasing process before the Minxian earthquake and the increasing process has continued after the main shock,which means that this study area is still in the danger of strong earthquakes.
基金the Special Research Fund for Earthquake Science,China (200708023)
文摘Source spectra,corner frequency and zero frequency amplitudes in near-source conditions were measured using waveform data from 989 earthquakes with magnitudes larger than ML2.0 observed by the Beijing Digital Telemetry Seismic Network in the Capital Circle Region of China and its surrounding areas from January 2002 to June 2006 by the Brune model.Relevant formulas that were used for the calculation of dynamic source parameters include rupture radius,seismic moment,seismic energy,stress drop,and apparent stress.Scaling relations and characteristics of temporal-spatial variations of these dynamic parameters before the MS5.1 Wenan earthquake in Hebei Province that occurred on July 20,2006 were analyzed.Results show that apparent stress,stress drop,and the ratio of seismic energy to the rupture radius had relatively high values in some areas before the Wenan earthquake.These high-value concentration areas were mainly distributed in the North China Plain seismic zone.As is seen from the time curves,parameters,such as apparent stress,stress drop,and ratio of seismic energy to rupture radius underwent significant ascending processes before the Wenan earthquake,but the variation in the corner frequency showed a descending trend.This result might be related to the enhancement of stress in the North China Plain seismic zone before the earthquake.
