A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are un...A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.展开更多
Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precurs...Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precursor waves in well water levels before strong earthquakes. It is indicated that the precursor waves often happen before strong earthquakes,with the ratio of occurrence up to 65% ( 41 /63 ) ; the precursor waves have poor generality in different observation wells,which may be related to the different well-aquifer system of different observation wells and the different source parameters of earthquakes. Compared to the seismic water level fluctuations in a single well,the number of precursor wave times recorded in well water levels before strong earthquakes is slightly less than that of seismic water level fluctuations,with a ratio between 39. 7% and 50. 7%, respectively. The number of observation wells with precursor wave recordings before earthquakes accounts for up to 66. 7% of the total number of observation wells. The precursor wave in well water level records has a certain generality in terms of the number of times recorded and the spatial distribution,except for its manifestation characteristics.展开更多
The Yutian earthquake with M_S7.3 happened on February 12,2014. The precursor monitoring ability is weak in that area. We found tendency anomalies and middle- and short-term anomalies from metal pendulum tilt measurem...The Yutian earthquake with M_S7.3 happened on February 12,2014. The precursor monitoring ability is weak in that area. We found tendency anomalies and middle- and short-term anomalies from metal pendulum tilt measurements in Hotan seismic station before the earthquake. And we also compared the anomalies with that of the M_S7.3 Yutian earthquake on March 21,2008. The tendency anomalies measured by the metal pendulum tiltmeter appeared since 2012 as tilting eastward. While the middle- and short-term anomalies were characterized by acceleration,pause and rapid change of tilt rate in two directions. The tendency anomalies of metal pendulum tilt records are the same before the two earthquakes. They both happened in the east direction. However,there are differences in duration,characteristic and earthquake intervals for the middle- and short-term anomalies.展开更多
基金sponsored by the Jinsha River Development Corporation Ltd. Program of China Three Gorges Cooperation (JSJ(06)007)
文摘A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.
基金supported jointly by the Joint Earthquake Science Foundation (A08051)Shanxi provincial key scientific and technological project (2006031106)+1 种基金Shanxi provincial natural science foundation project (2011011027)the earthquake trend tracing for 2011 (2011011401)
文摘Taking five underground water level observation wells with high earthquake response capability and located in Shanxi,Hebei and Inner Mongolia as study objects,this paper studies and discusses the generality of precursor waves in well water levels before strong earthquakes. It is indicated that the precursor waves often happen before strong earthquakes,with the ratio of occurrence up to 65% ( 41 /63 ) ; the precursor waves have poor generality in different observation wells,which may be related to the different well-aquifer system of different observation wells and the different source parameters of earthquakes. Compared to the seismic water level fluctuations in a single well,the number of precursor wave times recorded in well water levels before strong earthquakes is slightly less than that of seismic water level fluctuations,with a ratio between 39. 7% and 50. 7%, respectively. The number of observation wells with precursor wave recordings before earthquakes accounts for up to 66. 7% of the total number of observation wells. The precursor wave in well water level records has a certain generality in terms of the number of times recorded and the spatial distribution,except for its manifestation characteristics.
基金sponsored by the Earthquake Science Foundation of Xinjiang,China(201302)
文摘The Yutian earthquake with M_S7.3 happened on February 12,2014. The precursor monitoring ability is weak in that area. We found tendency anomalies and middle- and short-term anomalies from metal pendulum tilt measurements in Hotan seismic station before the earthquake. And we also compared the anomalies with that of the M_S7.3 Yutian earthquake on March 21,2008. The tendency anomalies measured by the metal pendulum tiltmeter appeared since 2012 as tilting eastward. While the middle- and short-term anomalies were characterized by acceleration,pause and rapid change of tilt rate in two directions. The tendency anomalies of metal pendulum tilt records are the same before the two earthquakes. They both happened in the east direction. However,there are differences in duration,characteristic and earthquake intervals for the middle- and short-term anomalies.
