Seismic noise tomography in the Chile ridge subduction region
Abstract
We used cross-correlation of ambient seismic noise recorded in the Chile Triple Junction (CTJ) region to estimate interstation surface wave time-domain Green's functions, and then inverted traveltimes to obtain crustal surface wave velocity models. Interstation distances within the Chile Ridge Subduction Project (CRSP) temporary seismic network ranged from 40 to ~100 km. We selected 365 d, and cross-correlated and stacked 24 hr of vertical component data at 38 stations pairs, resulting in nominally 703 traveltimes along assumed-straight interstation paths. Velocities in 2-D cells of 30 km × 30 km were calculated using a linear least-squares inversion of the Rayleigh wave group velocity traveltimes. Furthermore we performed a Rayleigh wave group velocity dispersion analysis to estimate the sensitivity of different period waves at depth and to calculate a 3-D shear velocity model of the Patagonian crust. The process was applied to cross correlation pairs determined in two period bands, 5-10 s, corresponding to shallow crustal velocities down to approximately 10 km depth, and 10-20 s, for velocities down to around 20 km. Our results show that cell velocities correlate well with known geological features. We find high-crustal velocities where the Patagonian Batholith outcrops or is likely present at depth, and low velocities correlate with the active volcanic arc of the Southern Volcanic Zone and the subducted Chile ridge in Taitao peninsula, where thermal activity of hot springs is present. High velocities in the mountainous portions of the southeastern study area appear to correlate with outcropping older metamorphic units. Low velocity in the east correlate with sequences of volcaniclastic deposits.
- Publication:
-
Geophysical Journal International
- Pub Date:
- September 2010
- DOI:
- 10.1111/j.1365-246X.2010.04691.x
- Bibcode:
- 2010GeoJI.182.1478G
- Keywords:
-
- Surface waves and free oscillations; Wave scattering and diffraction; Wave propagation; Continental margins: convergent; Crustal structure; Rheology: crust and lithosphere