IRISSeismic: getAvailability – R documentation

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getAvailability

Retrieve Channel metadata from IRIS DMC

Description

The getAvailability method obtains channel metadata for available channels from the IRIS DMC station web service and returns it in a dataframe.

Usage

getAvailability(obj, network, station, location, channel,
                starttime, endtime, includerestricted,
                latitude, longitude, minradius, maxradius)

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)
`includerestricted`	optional logical identifying whether to report on restricted data (default=`FALSE`)
`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

Details

The getAvailability method uses the station web service to obtain data for all available 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. This method is equivalent to the getChannel method with the following additional parameters attached to the url:

&includeavailability=true&matchtimeseries=true

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 non-available channels use getUnavailability.)

For more details see the web service documentation.

Value

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 snclId 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.

Author(s)

Jonathan Callahan jonathan@mazamascience.com

References

The IRIS DMC station web service:

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

This implementation was inspired by the functionality in the obspy get_stations() method.

https://docs.obspy.org/packages/autogen/obspy.clients.fdsn.client.Client.get_stations.html

Examples

# 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  getEvent web service to retrieve events 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],]

# Find all BHZ channels collecting data at the time of the quake and within 
# 5 degrees of the quake epicenter
channels <- getAvailability(iris,"*","*","*","BHZ",starttime,endtime,
                            lat=e$latitude,long=e$longitude,maxradius=5)
channels

IRISSeismic

Classes and Methods for Seismic Data Analysis

v1.6.2

GPL (>= 2)

Authors

Jonathan Callahan [aut], Rob Casey [aut], Gillian Sharer [aut, cre], Mary Templeton [aut], Chad Trabant [ctb]

Initial release