Attenuation of P and pP waves in Vrancea area – Romania |
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Authors: | Marian Ivan |
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Institution: | (1) Department of Geophysics, University of Bucharest, 6 Traian Vuia str., 020956 Bucharest o.p.37, Romania;(2) School of Ocean and Earth Sciences, Tongji University, 1239 Siping Rd., 200092 Shanghai, China |
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Abstract: | The seismic attenuation in the Vrancea region (Romania) is investigated from teleseismic recordings of P and pP waves during
the four major, intermediate-depth Romanian events that occurred since the onset of digital instrumentation. Most stations
are located in Canada and in the United States, being equipped with a variety of sensors, especially short-period ones. The
amplitude spectral ratio method is used, assuming no frequency dependence of the Q
P factor in the range 0.2–2 Hz. No apparent correlation between the derived attenuation value and the type of recording sensor
is observed. Lateral variations of the attenuation are obtained, with a very low Q
P area (values down to 33) located in the northwestern part of the Vrancea seismogenic volume. For the stations with different
azimuth angles in relation to the epicentral area, Q
P values routinely exceed 200. Most likely, the low attenuation values are related to an upwelling mantle material located
immediately beneath the crust, but limited in depth to at least 100 km. |
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Keywords: | attenuation P and pP waves spectral ratio Q P factor Vrancea (Romania) |
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