Q - Can we apply calibration to get m/s?

#1

I see in the metadata file that the conversion factor is there to convert counts to m/s. Is there a way to apply this to get m/s on the ordinate axis?

#2

Hi TideMan,

Yes, this is called “removing the instrument response” and there is a way to do this in some seismology softwares. If you’re familiar with python (and likely even if you’re not, yet), the easiest way to remove the response is by using ObsPy.

The following code is annotated and modified slightly from the manual page here: https://manual.raspberryshake.org/specifications.html#example-obspy-code-for-removing-response

# import dependencies
from obspy import read_inventory, read
from obspy.clients.fdsn import Client
from obspy.core.datetime import UTCDateTime

# set the FDSN server location, and start/end times
rs = Client(base_url='https://fdsnws.raspberryshakedata.com/')
start = UTCDateTime(2019, 1, 1, 0, 0, 0)
end = UTCDateTime(2019, 1, 1, 0, 30, 0)

# set the station name and download the response information
stn = 'R0000'            # your station name
inv = read_inventory('https://fdsnws.raspberryshakedata.com/fdsnws/station/1/query?network=AM&station=%s&level=resp&format=xml' % (stn))

# get waveforms and attach the response
stream = rs.get_waveforms('AM', stn, '00', 'EHZ', start, end)
stream.attach_response(inv)

# remove the response and plot
resp_removed = stream.remove_response()
resp_removed.plot()

Basically what’s happening here is: you download a piece of a waveform from a station, then you download and ingest the response file for that station. ObsPy reads the response information, then applies the response as a function to the deconvoluted waveforms, and outputs its best guess as to the ground motion based on that transformation.

Does that make sense? I’d be happy to answer questions about it.

Ian

#3

Yes, I understand the process.
My question was whether that could be applied to the ShakeNet display which has counts on the ordinate axis.

#4

I understand now, sorry for the confusion. That’s a question for @ivor or @wlee.

#5

we will consider this for a future update, thanks for the suggestion.

richard