getDataselect: Retrieve seismic data from IRIS DMC

Description

The getDataselect method makes a request of the IRIS DMC dataselect webservice and returns a Stream object in which individual Traces have been sorted by start time.

Usage

getDataselect(obj, network, station, location, channel, 
              starttime, endtime, quality, ignoreEpoch)

Arguments

obj

IrisClient object

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)

quality

optional character string identifying the quality (default = "B")

ignoreEpoch

optional logical defining behavior when multiple epochs are encountered (default = FALSE)

Value

A new Stream object is returned.

Details

This is the primary method for retreiving seismic data. Data requests are made through the dataselect webservice and returned data are parsed using the internal miniseed2Stream() function.

If the location argument contains an empty string to specify a 'blank' location code, a location code of "--" will be used in the dataselect request URL. (See http://service.iris.edu/fdsnws/dataselect/1/{dataselect documentation}.)

Error returns from the webservice will stop evaluation and generate an error message.

Sometimes, the station webservice will return multiple records for the same SNCL, each with a different scale or starttime. These represent different epochs with potentially different metadata parameters for the SNCL and, by default, will cause a 'Multiple epochs' error message to be generated.

Handling all possible metadata differences so that the data may be merged is beyond the scope of this package. Instead, to avoid errors, users may specify default=TRUE in which case the very first SNCL-epoch encountered will be used and all others will be discarded.

References

The IRIS DMC dataselect webservice:

http://service.iris.edu/fdsnws/dataselect/1/

This implementation is similar in functionality to the obspy dataselect function: