TY - JOUR

T1 - On measuring surface wave phase velocity from station-station cross-correlation of ambient signal

AU - Boschi, Lapo

AU - Weemstra, Cornelis

AU - Verbeke, Julie

AU - Ekström, Göran

AU - Zunino, Andrea

AU - Giardini, Domenico

PY - 2013/3/26

Y1 - 2013/3/26

N2 - We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the zero-crossings of the real part of the cross-correlation spectrum. Furthermore, the time-domain method, as implemented here and in the literature, practically involves the important approximation that interstation distance be large compared to seismic wavelength. In both cases, cross-correlations are ensemble-averaged over a relatively long period of time (1 yr). We verify that the two algorithms give consistent results, and infer that phase velocity can be successfully measured through ensemble-averaging of seismic ambient noise, further validating earlier studies that had followed either approach. The description of our experiment and its results is accompanied by a detailed though simplifed derivation of ambient-noise theory, writing out explicitly the relationships between the surface wave Green's function, ambient-noise cross-correlation and phase and group velocities

AB - We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the zero-crossings of the real part of the cross-correlation spectrum. Furthermore, the time-domain method, as implemented here and in the literature, practically involves the important approximation that interstation distance be large compared to seismic wavelength. In both cases, cross-correlations are ensemble-averaged over a relatively long period of time (1 yr). We verify that the two algorithms give consistent results, and infer that phase velocity can be successfully measured through ensemble-averaging of seismic ambient noise, further validating earlier studies that had followed either approach. The description of our experiment and its results is accompanied by a detailed though simplifed derivation of ambient-noise theory, writing out explicitly the relationships between the surface wave Green's function, ambient-noise cross-correlation and phase and group velocities

KW - Crustal structure

KW - Interferometry

KW - Seismic tomography

KW - Theoretical seismology

KW - Time-series analysis

UR - http://www.scopus.com/inward/record.url?scp=84875257919&partnerID=8YFLogxK

U2 - 10.1093/gji/ggs023

DO - 10.1093/gji/ggs023

M3 - Journal article

AN - SCOPUS:84875257919

VL - 192

SP - 346

EP - 358

JO - Geophysical Journal International

JF - Geophysical Journal International

SN - 0956-540X

IS - 1

ER -