getEvent: Retrieve seismic event information from the USGS NEIC

In IRISSeismic: Classes and Methods for Seismic Data Analysis

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)

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)

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.

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".

Author(s)

Jonathan Callahan [e-mail]

References

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

See Also

IrisClient-class,

Examples

  ## Not run: 
# 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')
  }

## End(Not run)

IRISSeismic documentation built on Oct. 16, 2022, 1:09 a.m.