S-wave velocity structure beneath the Mátra Mountains (Hungary) inferred from teleseismic receiver functions
Tóm tắt
The crustal and uppermost mantle structure beneath the Mátra Mountains has been investigated by means of the inversion of teleseismic P-wave receiver functions. Earthquakes recorded at the PSZ station in the period 1995–2000 with epicentral distances of between 20° and 100° and with magnitudes greater than 5.5 have been selected for analysis if their signal-to-noise ratio was sufficiently high. Source equalisation has been carried out to gain the radial and tangential receiver functions. The traces from similar backazimuths and distances were stacked to improve the data quality. The inversion of teleseismic waves coming from the north-east and the west shows that in the upper part of the crust the S-wave velocity has strong positive gradient, the middle crust exhibit almost uniform velocities, while in the lower crust and uppermost mantle the velocity increases monotonically. Velocity profiles for the eastern backazimuths are similar to the previous ones in the case of the upper and middle crust and uppermost mantle, however in the lower crust a low-velocity zone can be observed. The properties of polarity distribution of tangential receiver functions can be associated with WNW-dipping lower crustal interfaces.
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