Summary
This metric counts the times this data quality flag is set from 0 (default) to 1 in the fixed section of the miniSEED header. A flag value of 1 indicates that short-duration spikes have been detected in the data. Because spikes have shorter duration than the natural period of most seismic sensors, spikes often indicate a problem introduced at or after the datalogger. Not all dataloggers set this flag.
PH5-format data does not include miniSEED flag information; this metric will always return a value of 0 for data in the IRIS PH5 archive.
Uses
This metric can be searched to determine when a datalogger or station was known to have had this particular problem so that the station can be serviced or the affected data can be omitted from a user’s research.
If using this metric with the rrds service, be aware that a value of 0 (zero) can either mean that
- the datalogger detected 0 instances of this condition, or
- the datalogger does not set this flag, so it is unknown whether or not this condition occurred.
Unless all channels in an rrds request are known to set this flag, requesting only data with a count of 0 will not necessarily omit all data for which this condition occurred.
Data Analyzed
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
SEED Channel Types – ?H?, ?L?, ?N?, ?G?, ?P?, VM? | High Gain, Low Gain, Accelerometer, Gravimeter, Geophone, Mass Channels
Algorithm
- Request 24 hours of data for a single N.S.L.C.
- Count and report the number times this binary flag is set to 1.
Metric Values Returned
value – number of times this flag is set to 1 that day
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)
Notes
Not all dataloggers set this flag. For those that do not, a value of 0 does not necessarily mean that spikes are absent.
