Clarification on how to define subsurface stations in station file

[soraofs]

Hello,

I have a question regarding how to correctly define stations that are placed below the surface in the station file.

According to the documentation:

• z is the grid position (depth, positive DOWN) in kilometers
• elev is the elevation above the z grid position (positive UP) in kilometers

Let’s say we have a station with elevation of 50 m and the depth is 100 m.

In this case, how should I define the values in the station file?
Which of the following would be correct?

1. z = 100, elev = 50
2. z = 0, elev = -100
3. z = 100, elev = 0

Does this distinction make any practical difference in the location results?

Best regards

[alomax]

Hello,

Does this distinction make any practical difference in the location results?
Yes. Your 3 examples give different Z coordinates for the sensor. 1. will have Z=100-50km, 2. and 3. will have Z=100km, where Z is positive down.

I think what you need is:

z=0.1 elev=0.05

which is equivalent to:

z=0.05 elev=0
z=0.0 elev=-0.05

Best regards,
Anthony