The default specification of the receiver depths is the same as for SAFARI, i.e. through the parameters RD1, RD2 and NRD in Block VI, with
The NRD receivers are placed equidistantly in the vertical.
Non-equidistant Receiver Depths
In OASES the receiver depths can optionally be specified individually. The parameter NRD is used as a flag for this option. Thus, if NRD < 0the number of receivers is interpreted as -NRD, with the individual depths following immidiately following Block VI. As an example, SAFARI FIPP case 2 with receivers at 100, 105 and 120 m is run with the following data file:
SAFARI-FIPP case 2. V H F O # Complex frequency integration. 5 0 4 0 0 0 0 0 0 0 0 1500 0 0 0 1 0 100 1600 400 0.2 0.5 1.8 0 120 1800 600 0.1 0.2 2.0 0 95 100 100 -3 # 3 receivers 100.0 105.0 120.0 # Receiver depths in meters 300 1E8 1024 1 950 0 2048 0.0 12.5 0.006 0.5 0.5 5
The PP Post-processor is compatible and will depth-stack the traces at the correct depths.
Tilted Receiver Arrays
The new option `T' allows for specification of an array tilt in the vertical plane containing the source and the receivers.
The tilt angle and rotation origin is specified in the receiver depth line (Block VI):
| Standard | For option T |
| RD1 RD2 NR | ZREF ANGLE |
The vertical arrays are rotated by an angle `ANGLE' in deg relative to the vertical. The rotation is performed with origin at depth `ZREF'.
The parameters RD1, RD2 and NR always refer to the untilted case. In the tilted case these parameters do therefore define the array geometry and not the actual depths of the receivers in the tilted array. The same is the case for the graphics output produced by the post-processor PP.
The source(s) is always at the origin and is therefore not rotated. Thus, for zero-offset tilted VSP-s, the reference depth ZREF should be set equal to the source depth SD!