Retrieve Channel metadata from IRIS DMC
The getChannel method obtains channel metadata from the IRIS DMC station web service
and returns it in a dataframe.
getChannel(obj, network, station, location, channel,
starttime, endtime, includerestricted,
latitude, longitude, minradius, maxradius)obj |
|
network |
character string with the two letter seismic network code |
station |
character string with the station code |
location |
character string with the location code |
channel |
character string with the three letter channel code |
starttime |
POSIXct class specifying the starttime (GMT) |
endtime |
POSIXct class specifying the endtime (GMT) |
includerestricted |
optional logical identifying whether to report on restricted data |
latitude |
optional latitude used when specifying a location and radius |
longitude |
optional longitude used when specifying a location and radius |
minradius |
optional minimum radius used when specifying a location and radius |
maxradius |
optional maximum radius used when specifying a location and radius |
The getChannel method uses the station web service to obtain data for all channels that meet the criteria defined by the arguments
and returns that data in a dataframe. Each row of the dataframe represents a unique channel-epoch.
Each of the arguments network, station, location or channel may contain
a valid code or a wildcard expression, e.g. "BH?" or "*". Empty strings are converted to "*".
Otherwise the ascii string that is used for
these values is simply inserted into the web service request URL.
For more details see the webservice documentation.
A dataframe with the following columns:
network, station, location, channel, latitude, longitude, elevation, depth, azimuth, dip, instrument, scale, scalefreq, scaleunits, samplerate, starttime, endtime, snclId
Rows are ordered by snclId.
The snclId column, eg. "US.OCWA..BHE", is generated as a convenience. It is not part of the normal return from the station web service.
Note: The snclIds is not a unique identifier. If the time span of interest
crosses an epoch boundary where instrumentation was changed then multiple records (rows)
will share the same snclId.
Jonathan Callahan jonathan@mazamascience.com
The IRIS DMC station webservice:
This implementation was inspired by the functionality in the obspy get_stations() method.
# Open a connection to IRIS DMC webservices
iris <- new("IrisClient")
# Date of Nisqually quake
starttime <- as.POSIXct("2001-02-28",tz="GMT")
endtime <- starttime + 2*24*3600
# Use the getEvent web service to determine what events happened in this time period
events <- getEvent(iris,starttime,endtime,6.0)
events
# biggest event is Nisqually
eIndex <- which(events$magnitude == max(events$magnitude))
e <- events[eIndex[1],]
# Which stations in the US network are within 5 degrees of the quake epicenter?
stations <- getStation(iris,"US","*","*","BHZ",starttime,endtime,
lat=e$latitude,long=e$longitude,maxradius=5)
stations
# Get some detailed information on any BHZ channels at the "Octopus Mountain" station
channels <- getChannel(iris,"US","OCWA","*","BHZ",starttime,endtime)
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