getTraveltime: Retrieve seismic traveltime information from IRIS DMC

In IRISSeismic: Classes and Methods for Seismic Data Analysis

Retrieve seismic traveltime information from IRIS DMC

Description

The getTraveltime method obtains seismic traveltime data from the IRIS DMC traveltime web service and returns it in a dataframe.

Usage

getTraveltime(obj, latitude, longitude, depth, staLatitude, staLongitude)

Arguments

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

Details

The traveltime web service calculates travel-times for seismic phases using a 1-D spherical earth model.

Value

A dataframe with the following columns:

distance, depth, phaseName, travelTime, rayParam, takeoff, incident
  puristDistance, puristName

Rows are ordered by travelTime.

Author(s)

Jonathan Callahan [e-mail]

References

The IRIS DMC traveltime web service:

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

See Also

IrisClient-class

Examples

## Not run: 
# Open a connection to IRIS DMC webservices
iris <- new("IrisClient")

# Two days around the "Nisqually Quake"
starttime <- as.POSIXct("2001-02-27", tz="GMT")
endtime <- starttime + 3600 * 24 * 2

# Find biggest seismic event over these two days -- it's the "Nisqually"
events <- getEvent(iris, starttime, endtime, minmag=5.0)
bigOneIndex <- which(events$magnitude == max(events$magnitude))
bigOne <- events[bigOneIndex[1],]

# Find US stations that are available within an hour of the event
start <- bigOne$time
end <- start + 3600
availability <- getAvailability(iris, "US", "", "", "BHZ",
                                starttime=start, endtime=end,
                                latitude=bigOne$latitude, longitude=bigOne$longitude,
                                minradius=0, maxradius=10)
    
# Get the station the furthest East
minLonIndex <- which(availability$longitude == max(availability$longitude))
snclE <- availability[minLonIndex,]

# Plot the BHZ signal from this station
st <- getDataselect(iris,snclE$network,snclE$station,snclE$location,snclE$channel,
                    start,end)

# Check that there is only a single trace and then plot it
length(st@traces)
tr <- st@traces[[1]]
plot(tr, subsampling=1) # need subsmpling=1 to add vertical lines with abline()

# Find travel times to this station
traveltimes <- getTraveltime(iris, bigOne$latitude, bigOne$longitude, bigOne$depth,
                             snclE$latitude, snclE$longitude)

# Look at the list                             
traveltimes

# mark the P and S arrival times
pArrival <- start + traveltimes$travelTime[traveltimes$phaseName=="P"]
sArrival <- start + traveltimes$travelTime[traveltimes$phaseName=="S"] 
abline(v=pArrival, col='red')
abline(v=sArrival, col='blue')

## End(Not run)

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