SAGE Facility MUSTANG metrics Web Service Documentation

This metric computes the difference between the minimum and maximum sample value (range) in a rolling 300-second window, reporting the largest range value in counts found in a daily 24-hour period.

This metric can help characterize the largest seismic or noise-related signal over the course of a day, excluding extremely long period signals. This may be useful for identifying stations that have large sensor pings, spikes, or other recurrent signals that, e.g., may potentially cause false STA/LTA triggers in an earthquake early warning system.

Traces – one N.S.L.C (Network.Station.Location.Channel) per measurement
Window – 24 hours starting at 00:00:00 UTC
Data Source – IRIS miniSEED archive or IRIS PH5 archive

SEED Channel Types – ?H?, ?L?, ?N?, ?G?, ?P? | High Gain, Low Gain, Accelerometer, Gravimeter, Geophone | excluding very long period channels

• Request 24 hours of time series data for a single N.S.L.C.
• Fill data gaps with values of NA
• Subset data into 300-second windows with 50% overlap (150 seconds), for a total of 575 data segments.
• For each window, find the maximum and minimum amplitude value:
  

  For i=1,N samples in the time series x:
      if (x(i) < min) {min = x(i)}
      if (x(i) > max) {max = x(i)}
  

• For each window w, calculate the difference between the maximum and minimum amplitude values and store in a vector:
  

  range(w) = max(w)-min(w)
  

• Identify and report the largest range value for the requested data:
  

  maxRange = maximum(range(w))
  

value – maximum amplitude range value in counts
target – the trace analyzed, labeled as N.S.L.C.Q (Network.Station.Location.Channel.Quality)
start – beginning of the data day requested (00:00:00 UTC)
end – end of the data day requested (truncated as 23:59:59 UTC)
lddate – date/time the measurement was made and loaded into the MUSTANG database (UTC)

• gillian@iris.washington.edu