IRISSeismic (version 1.6.6)

getEvent: Retrieve seismic event information from the USGS NEIC

Description

The getEvent method obtains seismic event data from the USGS NEIC event webservice.

Usage

getEvent(obj, starttime, endtime, minmag, maxmag, magtype,
         mindepth, maxdepth)

Value

A dataframe with the following columns:

eventId ,time, latitude, longitude, depth, author, cCatalog, contributor,
  contributorId, magType, magnitude, magAuthor, eventLocationName 

Rows are ordered by time.

NOTE: column names are identical to the names returned from the event web service with the exception of "latitude" for "lat" and "longitude" for "lon". The longer names are used for internal consistency -- all other web services return columns named "latitude" and "longitude".

Arguments

obj

an IrisClient object

starttime

POSIXct class limiting results to events occurring after starttime (GMT)

endtime

POSIXct class limiting results to events occurring before endtime (GMT)

minmag

optional minimum magnitude

maxmag

optional maximum magnitude

magtype

optional magnitude type

mindepth

optional minimum depth (km)

maxdepth

optional maximum depth (km)

Author

Jonathan Callahan

Details

The getEvent method uses the event web service to obtain data for all events that meet the criteria defined by the arguments and returns that data in a dataframe. Each row of the dataframe represents a unique event.

getEvent calls to the IRIS event webservice now go to https://earthquake.usgs.gov/fdsnws/event/1/. If obj@site is something other than "https://service.iris.edu", getEvent will point to obj@site/fdsnws/event/1/. The event service must be able to output format=text.

References

The USGS event webservice: https://earthquake.usgs.gov/fdsnws/event/1/

See Also

IrisClient-class,

Examples

  if (FALSE) {
# NOTE:  'maps' and 'mapdata' packages must be installed
#require(maps)
#require(mapdata)

# Open a connection to IRIS DMC webservices
iris <- new("IrisClient")

# Get events > mag 5.0 over a week in June of 2012
starttime <- as.POSIXct("2012-06-21", tz="GMT")
endtime <- starttime + 3600 * 24 * 7
result <- try(events <- getEvent(iris, starttime, endtime, minmag=5.0))
if (inherits(result,"try-error")) {
  message(geterrmessage())
} else {

# Look at all events
  print(paste(nrow(events),"earthquakes found with magnitude > 5.0"))
  
# Plot events on a map
  #map('world')
  #points(events$longitude, events$latitude, pch=16, cex=1.5, col='red')
  #labels <- paste(" ", as.character(round(events$magnitude,1)), sep="")
  #text(events$longitude, events$latitude, labels=labels, pos=4, cex=1.2, col='red3')
  }
}