Ambient noise station-correlation spectra for USArray stations

DUG-US secondary stations.

K13A-TA K14A-TA L12A-TA L13A-TA M11A-TA M12A-TA M13A-TA N11A-TA N12A-TA N13A-TA
O11A-TA O12A-TA P11A-TA P12A-TA Q11A-TA Q12A-TA