In 2004, China＇s digital seismic observation network project began to deploy 40 sets YRY-4 four-component borehole strainmeters in order to monitor earthquake preparation process. The paper describes observed solid t...In 2004, China＇s digital seismic observation network project began to deploy 40 sets YRY-4 four-component borehole strainmeters in order to monitor earthquake preparation process. The paper describes observed solid tidal strain discreteness and tidal factor anisotropy, analyzes the reliability of observational data and discusses the cause for this phenomenon. After getting rid of interferences, the network, in two years practice, has observed several pre-seismic strain anomalies at stations close to epicenters especially in the Wenchuan Ms8.0 megaquake. It shows that this borehole strainmeter network is capable of monitoring seismogenic process.展开更多
At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a...At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.展开更多
Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It has been used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and It...Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It has been used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in re- search fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse and so on. Borehole strainmeter has been improved rapidly and tends to get more and more components included in one probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake, earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years, borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.展开更多
基金supported by National Science Commission of China(No.1978-002)China Earthquake Administration(No.1982-220)
文摘In 2004, China＇s digital seismic observation network project began to deploy 40 sets YRY-4 four-component borehole strainmeters in order to monitor earthquake preparation process. The paper describes observed solid tidal strain discreteness and tidal factor anisotropy, analyzes the reliability of observational data and discusses the cause for this phenomenon. After getting rid of interferences, the network, in two years practice, has observed several pre-seismic strain anomalies at stations close to epicenters especially in the Wenchuan Ms8.0 megaquake. It shows that this borehole strainmeter network is capable of monitoring seismogenic process.
基金supported by the Special Fund for Earthquake Research in the Public Interest(No.201108009)
文摘At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.
基金National Natural Science Foundation of China (40374011) and Joint Seismological Foundation of China (1040037).
文摘Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It has been used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in re- search fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse and so on. Borehole strainmeter has been improved rapidly and tends to get more and more components included in one probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake, earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years, borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.
