Physics
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011geoji.184..287k&link_type=abstract
Geophysical Journal International, Volume 184, Issue 1, pp. 287-300.
Physics
2
Interferometry, Surface Waves And Free Oscillations, Seismic Tomography, Crustal Structure, Europe
Scientific paper
We process seismic broad-band data from southern Norway by cross correlation of ambient seismic noise in view of getting a better image of the crustal structure in the area. The main data set sterns from the temporary MAGNUS network which operated continuously from 2006 September to 2008 June. Additionally, data from permanent stations of the National Norwegian Seismic Network, the NORSAR array and GSN stations in the region are used. We compute vertical component cross-correlation functions using 41 receivers for 3-month time windows. Evaluation of the azimuthal and temporal variation of signal-to-noise ratios (SNRs) and f-k analysis of data from NORSAR array between 3 and 25 s period shows that the dominant source areas of seismic noise are located to the west and north of the network during most of the measurement time, which corresponds well to the Norwegian coast line. During summer months, the SNRs decrease but the azimuthal distribution becomes more uniform between 7 and 12 s period, suggesting a more diffuse character of the wavefield. Primary ocean microseisms above 12 s show different dominant source azimuths during this time period compared to the winter months. Time-frequency analysis is applied to measure Rayleigh wave group velocity dispersion curves between each station pair for each 3-month correlation stack and the mean and variance of all dispersion curves is computed for each path. After rejection of low-quality data, a careful analysis shows that the group velocities are not biased by noise directionality. We invert the data for group velocity maps at period bands between 3 and 25 s. At short periods, we find an average Rayleigh wave group speed of about 3 km s-1 and velocity anomalies that correlate very well with local surface geology. While higher velocities (+5 per cent) can be associated with the Caledonian nappes in the central part of southern Norway, the Oslo Graben is reflected by negative velocity anomalies (-3 to -5 per cent). At longer periods, group velocities correlate well with the variation of Moho depths beneath southern Norway.
Kohler Andreas
Maupin Valérie
Weidle Christian
No associations
LandOfFree
Directionality analysis and Rayleigh wave tomography of ambient seismic noise in southern Norway does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Directionality analysis and Rayleigh wave tomography of ambient seismic noise in southern Norway, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Directionality analysis and Rayleigh wave tomography of ambient seismic noise in southern Norway will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1594917