Shear-wave structure of southern Sweden from precise phase-velocity measurements of ambient-noise data
عنوان دوره: هجدهمین کنفرانس ژئوفیزیک ایران
نویسندگان
1دانشکده مهندسی معدن، دانشگاه صنعتی اصفهان
2Department of Earth Sciences, Uppsala University, Sweden
چکیده
We analyze continuous recordings from 36 stations (630 station-pairs) over a year to build the first crustal shear-wave model based on the ambient-noise method in southern Sweden. Cross-correlations of vertical components between all the stations are computed, and phase-velocity dispersion curves measured. We invert cross-correlation envelopes for an azimuthal source distribution. We then estimate velocity measurement bias for each station pair by comparing synthetic cross correlations calculated with that source distribution and a uniform source distribution. Dispersion curves are corrected for the estimated bias before tomography. After constructing phase-velocity maps in different period ranges between 3 and 30 s, they are combined and inverted for shear velocity beneath each grid point. Anomalies in the model are interpreted in relation to intrusions and tectonic features of the region. The bias due to an uneven source distribution is generally small (< 1.2 %). The bias correction significantly reduces residual data variance at the longest periods where it is biggest.
کلیدواژه ها
 
Title
Shear-wave structure of southern Sweden from precise phase-velocity measurements of ambient-noise data
Authors
Hamzeh Sadeghisorkhani, Olafur Gudmundsson, Ka Lok Li
Abstract
We analyze continuous recordings from 36 stations (630 station-pairs) over a year to build the first crustal shear-wave model based on the ambient-noise method in southern Sweden. Cross-correlations of vertical components between all the stations are computed, and phase-velocity dispersion curves measured. We invert cross-correlation envelopes for an azimuthal source distribution. We then estimate velocity measurement bias for each station pair by comparing synthetic cross correlations calculated with that source distribution and a uniform source distribution. Dispersion curves are corrected for the estimated bias before tomography. After constructing phase-velocity maps in different period ranges between 3 and 30 s, they are combined and inverted for shear velocity beneath each grid point. Anomalies in the model are interpreted in relation to intrusions and tectonic features of the region. The bias due to an uneven source distribution is generally small (< 1.2 %). The bias correction significantly reduces residual data variance at the longest periods where it is biggest.
Keywords
Ambient-noise tomography, Source distribution, Bias correction, Crustal Structure