Ambient noise station-correlation spectra for USArray stations

W15A-TA secondary stations.

115A-TA 116A-TA U12A-TA V11A-TA V12A-TA W12A-TA W13A-TA W14A-TA X13A-TA X14A-TA
X15A-TA Y12C-TA Y13A-TA Y14A-TA Z14A-TA
DAN-CI IRM-CI NEE-CI NEE2-CI PDM-CI
WUAZ-US