| freq.magnitude {ssEDA} | R Documentation |
Frequency-magnitude plot of the selected events. That is, for a given magnitude m (x axis), the log10 of the proportion of events with magnitude greater than m is given on the y axis. The slope is commonly referred to as the b-value.
freq.magnitude(events, delta=0.1, bvalue=NA, estimate="ml", plot=TRUE)
events |
defines the events to be plotted. It is an object of class "subset", generally created by subsetcircle, subsetpolygon, subsetrect or subsetsphere.
|
delta |
the interval width between points on the graph. Note that the limits of
magnitudes plotted (x axis) are determined by minmag and
maxmag in the object events. Hence, maxmag-minmag must be
a multiple of delta.
|
bvalue |
default is NA, in which case a least squares regression line is
fitted through the points. If not NA, a line with the given slope
is plotted.
|
estimate |
takes the values "ml" (default) or "ls", meaning maximum
likelihood or least squares respectively. It determines the
estimation method used for the b-value. In the case of least
squares, the intercept parameter is estimated, whereas in the case
of maximum likelihood the log of the cumulative proportion is set to
zero at the minimum magnitude. |
plot |
logical, default is TRUE. Determines whether the frequency magnitude distribution is plotted. |
The estimated b-value is returned if the function call is assigned to an object, otherwise NULL.
depth.hist, freq.cusum,
magnitude.cusum, magnitude.time,
epicentres, threeD, timeplot,
multigraph
# This example requires the NZ catalogue
require(ssNZ)
b <- subsetrect(NZ, minday=julian(1,1,1964), maxday=julian(1,1,1993),
mindepth=40, maxdepth=120, minmag=4)
freq.magnitude(b)