IRISSeismic (version 1.0.7-1)

eventWindow: Return a portion of a trace surrounding an event.

Description

The eventWindow method of Trace uses the picker returned by the STALTA() method to center a window around the the event detected by the picker.

Usage

eventWindow(x, picker, threshold, windowSecs)

Arguments

x

a Trace object

picker

a picker as returned by the STALTA() method applied to this Trace

threshold

the threshold at which the picker is 'triggered'

windowSecs

the size of the window in secs

Value

A new Trace object is returned.

Details

This utility function uses the trace method triggerOnset() to determine p-wave onset followed by the slice() method to return a new Trace object of the desired size centered near the event onset.

When no threshold value is supplied, the default value is calculated as:

threshold=quantile(picker,0.999,na.rm=TRUE)

See Also

STALTA, triggerOnset

Examples

  ## Not run: 
# # Open a connection to IRIS DMC webservices
# iris <- new("IrisClient")
# 
# starttime <- as.POSIXct("2002-04-20", tz="GMT")
# endtime <- as.POSIXct("2002-04-21", tz="GMT")
# 
# # Get the waveform
# st <- getDataselect(iris,"US","OXF","","BHZ",starttime,endtime)
# 
# # Seismic signal in third trace
# tr <- st@traces[[3]]
# 
# # Create a picker
# picker <- STALTA(tr,3,30)
# threshold <- quantile(picker,0.99999,na.rm=TRUE)
# 
# # 3 rows
# layout(matrix(seq(3)))
# 
# # Plot trace and p-wave closeups
# closeup1 <- eventWindow(tr,picker,threshold,3600)
# closeup2 <- eventWindow(tr,picker,threshold,600)
# plot(tr)
# plot(closeup1,subsampling=1)
# abline(v=length(closeup1)/2, col='red')
# plot(closeup2,subsampling=1)
# abline(v=length(closeup2)/2, col='red')
# 
# # Restore default layout
# layout(1)
#   ## End(Not run)