Time-space subsurface monitoring using seismic ambient noise

Seismic ambient noise recorded by the ocean bottom nodes (OBNs) in the Gorgon gas field, Western Australia is used to compute time-lapse seafloor models. The extracted hourly cross-correlation (CC) functions of 0.1 – 1 Hz contain mainly Scholte waves with very high signal to noise ratio. The conventional time-lapse analysis suggests relative velocity variations (dv/v) up to 1% assuming a spatially homogeneous dv/v, with a likely 24-hour cycling pattern. With high-resolution baseline models from full waveform inversion of Scholte waves, we propose a wave-equation based double-difference inversion method using differential arrival times for localizing the time-lapse dv/v in the heterogeneous subsurface in depth. The time-lapse velocity models show velocity increase/decrease patterns in agreement with that from conventional analysis, with more notable changes at the shallower depths. We show the feasibility of using ambient noise for quantitative 4-D monitoring of subsurface property changes. --- Zoom connection information: Topic: Marine Geosciences Seminar - Peng Guo - September 21st Time: Sep 21, 2022 11:00 AM Paris Join Zoom Meeting https://u-paris.zoom.us/j/84678895810?pwd=RCtRdk1hdDROVjdhRSsvZVo1Y04vZz09 Meeting ID: 846 7889 5810 Passcode: 676544 One tap mobile +33170372246,,84678895810#,,,,*676544# France +33170379729,,84678895810#,,,,*676544# France Dial by your location +33 1 7037 2246 France +33 1 7037 9729 France +33 1 7095 0103 France +33 1 7095 0350 France +33 1 8699 5831 France Meeting ID: 846 7889 5810 Passcode: 676544 Find your local number: https://u-paris.zoom.us/u/kcMHxC5Fu7 Join by SIP Join by H.323 162.255.37.11 (US West) 162.255.36.11 (US East) 115.114.131.7 (India Mumbai) 115.114.115.7 (India Hyderabad) 213.19.144.110 (Amsterdam Netherlands) 213.244.140.110 (Germany) 103.122.166.55 (Australia Sydney) 103.122.167.55 (Australia Melbourne) 209.9.211.110 (Hong Kong SAR) 64.211.144.160 (Brazil) 69.174.57.160 (Canada Toronto) 65.39.152.160 (Canada Vancouver) 207.226.132.110 (Japan Tokyo) 149.137.24.110 (Japan Osaka) Meeting ID: 846 7889 5810 Passcode: 676544