getDistaz: Retrieve great circle distance information from IRIS DMC

Description

The getDistaz method obtains great circle distance data from the IRIS DMC distaz web service.

Usage

getDistaz(obj, latitude, longitude, staLatitude, staLongitude)

Value

A dataframe with the following columns:


ellipsoid.semiMajorAxis, ellipsoid.flattening, ellipsoid.name, fromlat, fromlon, tolat, tolon,
  azimuth,backAzimuth, distance, distanceMeters

Where fromlat is the event latitude, fromlon is the event longitude, tolat is the station latitude, and tolon

is the station longitude. azimuth, backAzimuth, and distance are measured in degrees. distanceMeters is distance in meters. ellipsoid.semiMajorAxis, ellipsoid.flattening, and ellipsoid.name refer to the World Geodetic System standard coordinate system version used to correct for ellipticity when converting to geocentric latitudes.

Only a single row is returned.

Arguments

obj: an IrisClient object
latitude: latitude of seismic event
longitude: longitude of seismic event
staLatitude: latitude of seismic station
staLongitude: longitude of seismic station

Author

Jonathan Callahan jonathan@mazamascience.com

Details

The distance-azimuth service will calculate the great-circle angular distance, azimuth, and back azimuth between two geographic coordinate pairs. Azimuth and back azimuth are measured clockwise from North.

References

The IRIS DMC distaz webservice:

https://service.iris.edu/irisws/distaz/1/