Usage of peak_ground_motion function


I looked up this function peak_ground_motion from obspy.signal.freqattributes. Is “data” an array of amplitudes from my time series? In which unit is the returned PGA value? cm/s²?

from obspy.signal.freqattributes import peak_ground_motion
from obpy import read
st = read(file)
pga = peak_ground_motion(st[0].data, delta = st[0], freq = 1)[0]

Appreciate any help, thanks!

Hi @victorjs, I just had a look at the code for that function, and it appears that the base units should be the same as the input data. So if your input data are in velocity with m/s (as is most common when removing the instrument response), then you should be getting out PGA = m/s**2.

Hi @shicks-seismo, thanks for the reply! I’m trying to understand how and why to remove the instrument response from my data acquired with conventional one component geophones. Do you know what sort of informations are needed for this step? Thanks.