Fig. 2
Four examples of CRG records in the T-X domain and Ï„-p domain. (A), (B), (C), and (D) indicate the profiles at stations No. 5228 (26.0 km), No. 8135 (40.0 km), No. 10,226 (50.0 km) and No. 14,306 (70.2 km), respectively. Fifty-one adjacent DAS stations were collected and displayed, aligned by offset distance in the CRGs in the T-X domain (Top panels). A bandpass filter from 8Â Hz to 15 Hz was applied to each trace in the CRG records. Each trace was normalized by its amplitude, and all travel times were reduced by 3.5 km/s. Within a distance of 5Â km, the refracted P-wave can be identified following the arrival of the direct water wave. At distances between 5Â km and 15 km, the refracted P-wave is clearly seen as the first arrival. Transformation of CRG data from the T-X domain to the Ï„-p domain was performed separately for westward and eastward shooting from the receiver. Panels of the left and right bottom in each figure display the Ï„-p domain for westward and eastward shooting, respectively. Black arrows indicate the trajectories of refracted waves in the Ï„-p domain.
