Intrinsic absorption and scattering attenuation in the southern part of the Netherlands |
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| Authors: | FH Goutbeek B Dost T van Eck |
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| Institution: | (1) Royal Netherlands Meteorological Institute, Seismology Division, PO Box 201, 3730 AE De Bilt, the Netherlands |
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| Abstract: | We present the first systematic study of attenuation derived from the S-wave coda in the frequency range 1-32 Hz for the southern part of the Netherlands and its surroundings. For this we used two methods, the codaQ (Q
c) method and the Multiple Lapse Time Window (MLTW) method. In the interpretation of the results both single and multiple scattering in a half space are considered. Our aim is to validate these interpretations in our region and to try to identify theeffects of attenuation due to intrinsic absoprtion (Q
i)and scattering attenuation (Q
s). For this we analyzedmore than 100 3-component high-quality digital seismograms from 43 crustalevents and 23 different stations in the Netherlands, Germany and Belgium.Coda Q results show smaller Q
c (=Q
0fn) values for epicentral distances shorter than 25 km (Q
0=90) compared to larger epicentral distances (Q
0=190), but similar frequency dependence ( f-0.9). Interpretation of MLTW results provided a seismic albedo smaller then 0.5, suggesting that the intrinsic absorption dominates over scattering in this region. Both Q
i and Q
s show similar frequency dependences as Q
c. These results are comparable to those obtained in other areas, but we also show that more sophisticated models are required to remove ambiguities in the interpretation. For short lapse times and shortevent-station distances we find for the simple half space model a correspondinginterpretation of both methodologies, where Q
c correspondsto Q
t, suggesting that a model with single scattering in ahalf space is appropriate. For long lapse times and long event station distances, however, we find that the S-wave coda is, most probably, too much influenced by crust-mantel heterogenities and more sophisticated Qinversion models using larger data sets are required for more reliable attenuation estimates. |
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| Keywords: | coda Q intrinsic attenuation the Netherlands Roer Valley Graben scattering attenuation |
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