TY - JOUR

T1 - On the Theory of the Microseismic Sounding Method

AU - Яновская, Татьяна Борисовна

PY - 2017

Y1 - 2017

N2 - Based on the theory of surface waves in a media with weak lateral heterogeneities, an explanationis given for the peculiarities that are considered as prospecting indicators in the microseismic soundingmethod (MSM). According to this theory, during the propagation of surface waves in such media, their localcharacteristics are the same as in the case of propagation in a horizontally homogeneous medium characterizedby the same vertical velocity section as underlying a given point. Since the wave energy flux through asemiinfinite vertical strip is conserved, the amplitude of the wave is redistributed along the vertical. Based onthis principle and simple physical considerations, it is shown that above a low-velocity domain, the amplitudesof microseisms should increase at wavelengths approximately exceeding the depth of the anomaly by afactor of three and decrease at small wavelengths. The model calculations show that variation of spectralamplitudes only allows a depth to the anomaly to be estimated rather than its average extent. Practically identicalspectra characterize the anomalies in which the product of the vertical extent of the anomaly and thevelocity contrast is approximately similar.

AB - Based on the theory of surface waves in a media with weak lateral heterogeneities, an explanationis given for the peculiarities that are considered as prospecting indicators in the microseismic soundingmethod (MSM). According to this theory, during the propagation of surface waves in such media, their localcharacteristics are the same as in the case of propagation in a horizontally homogeneous medium characterizedby the same vertical velocity section as underlying a given point. Since the wave energy flux through asemiinfinite vertical strip is conserved, the amplitude of the wave is redistributed along the vertical. Based onthis principle and simple physical considerations, it is shown that above a low-velocity domain, the amplitudesof microseisms should increase at wavelengths approximately exceeding the depth of the anomaly by afactor of three and decrease at small wavelengths. The model calculations show that variation of spectralamplitudes only allows a depth to the anomaly to be estimated rather than its average extent. Practically identicalspectra characterize the anomalies in which the product of the vertical extent of the anomaly and thevelocity contrast is approximately similar.

KW - Rayleigh waves, microseisms, MSM

M3 - Article

VL - 53

SP - 819

EP - 824

JO - Izvestiya, Physics of the Solid Earth

JF - Izvestiya, Physics of the Solid Earth

SN - 1069-3513

IS - 6

ER -