Surface wave tomography on a large-scale seismic array combining ambient noise and teleseismic earthquake data

Abstract

We discuss two array-based tomography methods, ambient noise tomography (ANT) and two-planewave earthquake tomography (TPWT), which are capable of taking advantage of emerging large-scale broadband seismic arrays to generate high resolution phase velocity maps, but in complementary period band: ANT at 8-40 s and TPWT at 25-100 s period. Combining these two methods generates surface wave dispersion maps from 8 to 100 s periods, which can be used to construct a 3D vS model from the surface to ∼200 km depth. As an illustration, we apply the two methods to the USArray/Transportable Array. We process seismic noise data from over 1 500 stations obtained from 2005 through 2009 to produce Rayleigh wave phase velocity maps from 8 to 40 s period, and also perform TPWT using ∼450 teleseismic earthquakes to obtain phase velocity maps between 25 and 100 s period. Combining dispersion maps from ANT and TPWT, we construct a 3D vS model from the surface to a depth of 160 km in the western and central USA. These surface wave tomography methods can also be applied to other rapidly growing seismic networks such as those in China.

Efficient Inversion of Multi-frequency and Multi-source Electromagnetic Data: Final report

“…This stands in contrast to the seismic images (e.g., Wagner et al, 2010;Yang et al, 2011; see also Fig. 2F), which show substantial slow anomalies in the mantle immediately beneath Yellowstone.…”

“…The footprint of the conductive anomaly in all of models 1-3 coincides with that of the very prominent low in shear wave velocities inferred at the top of the mantle from surface wave tomography (Obrebski et al, 2010;Wagner et al, 2010;Gao et al, 2011;Yang et al, 2011; see also Fig. 2F).…”

“…The resulting inverse solution (model 3;Figs. DR3 and DR4) is noticeably rougher and has excessively conductive crust, averaging ~3000 S below the SRP, with peak values exceeding 10,000 S. Such high conductivities are diffi cult to explain other than with free saline fl uids distributed throughout the mid-to lower crust, an inference which is diffi cult to reconcile with seismic surface wave studies that reveal normal to fast lower crustal velocities in this area (Gao et al, 2011;Yang et …”

“…Surface wave inversions of USArray data show fast anomalies beneath the eastern SRP and Yellowstone at mid-to lower crustal depths (except directly beneath and near the Yellowstone caldera), but a very pronounced lowvelocity anomaly in the mantle between the Moho and 200 km depth, extending southwest from Yellowstone caldera in the direction of North American plate motion (Obrebski et al, 2010;Wagner et al, 2010;Gao et al, 2011;Yang et al, 2011).…”

Lithospheric structure beneath the northern Central Andean Plateau from the joint inversion of ambient noise and earthquake‐generated surface waves

“…ANT has been especially successful in imaging the shallow crust at local to continental scales [ Lin et al ., ; Yang et al ., ; Bensen et al ., ; Zheng et al ., ; Saygin and Kennett , ; Yang et al ., ; Ward et al ., ; Delph et al ., ] because it does not use earthquake‐generated surface waves that attenuate rapidly at periods that are primarily sensitive to the shallow crust (<20 s). Since the ANT and TPWT methods are in principle sensitive to the same rock properties of the solid Earth, combining the two methods to produce SWD measurements in the period range of 8–143 s has become a popular approach for investigating the whole lithospheric structure [ Yang et al ., ; Porter et al ., ; Wagner et al ., ; Ma and Clayton , ]. In the following sections, we briefly describe the details of the TPWT and ANT methods and our approach of combining them into a joint inversion for the 3‐D S wave velocity structure of the northern CAP.…”