HR: 1340h
AN: S33B-1103    [Abstracts]
TI: Experiments On Vibroseismic Monitoring Of The Earth's Crust In Siberia.
AU: * Emanov, A
EM: emanov@gs.nsc.ru
AF: Geophysical Survey SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AU: Seleznev, V
EM: sel@gs.nsc.ru
AF: Geophysical Survey SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AU: Chichinin, I
EM: chihis@uiggm.nsc.ru
AF: Institute of Geophysics SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AU: Soloviev, V
EM: solov@gs.nsc.ru
AF: Geophysical Survey SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AU: Zhemchugova, I
EM: emanov@gs.nsc.ru
AF: Geophysical Survey SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AU: Kashun, V
EM: emanov@gs.nsc.ru
AF: Geophysical Survey SB RAS, pr. akad. Koptyuga, 3, Novosibirsk, 630090 Russian Federation
AB: The long-term experiment on vibroseismic monitoring of the Earth' crust was begun in 1997 in Thom'-Kolyvan' fold zone. As excitation sources two vibrators of 100 and 40 ton force were used. The recording was carried out by sensors on source platform at a depth of 3m under platform and in "Novosibirsk" seismological station at a distance of 49km from vibrator. Besides temperature measuring was carried out by a set temperature detectors from subgrade under vibrator up to 3m depth. The experimental work are focussed on study of long-term experiment features with high-power vibrators in conditions of seasonal effects of a ground state, as well as on studies of time variations of seismic wave travel times and on test of developed hardware resources. The fixed vibrator is located in the open and is working for years without installation modifications. The mobile vibrator was located near, and a year later it has been located in underground pavilion. Thus a temperature stabilization of a ground under vibrator has been achieved. The seasonal variations of frequency characteristic of vibrator radiation have been investigated. Only process of a freezing and thawing of a ground was demonstrated to have effect on vibrator radiation. There is both a winter type of performance and summer one and transition periods between them. The seismograms of remote zone test cyclical modifications winter/summer too. Travel time attributes of waves have no dependence on process of freezing/thawing of a ground. Dynamic behavior has a pronounced relation with perfect recurrence of dynamics for the same level of freezing or thawing at different years. The fixed vibrator works in operating condition, when the radiant resonance is in operating frequency range. Taking into account that the resonance is most sensitive to the ground state under a source in experiments with 40-ton vibrator the working range of soundings was removed after resonance spectral region. In this case on measurements in near zone the essential stabilization in time of radiation spectrum is observed. However measurements in far field have shown the same seasonal modifications of seismograms. Dependence on processes of ground freezing and thawing has remained. The placing of 40-ton vibrator in underground pavilion stabilized even greater a signal spectrum, leaving in a medium, but the seismograms at a distance test as before seasonal modifications of wave dynamic characteristics. It has been found by more detail researches that the freezing and thawing of a ground have effect not only on radiation spectrum, but also on the directional diagram of the source. To remove influence of ground seasonal modifications to a spectrum is much easier, than to stabilize an invariability of the directional diagram. The surprising thing is that the seismograms of different years for identical level of ground freezing surprising coincide with each other on wave dynamics. As a result of experiments is shown that for medium monitoring when working with vibrator there is a high accuracy of determination of seismic wave travel times, but the dynamic characteristics of waves test seasonal variations connected to a freezing and thawing of breeds under a source. Their use demands a control over the process of freezing and thawing of a ground.
DE: 7223 Seismic hazard assessment and prediction
DE: 7294 Instruments and techniques
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1242)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting