GRTo (version 1.3)

fmddisc: Analysis of Discontinuities in Frequency Magnitude Distributions

Description

This function finds significant discontinuities in Frequency Magnitude Distributions (FMD).

Usage

fmddisc(file, header = FALSE, colid = 1, nrep = 200, title = "fmddisc")

Arguments

file

filename of the file to be loaded

header

whether file contains headers or not

colid

field number for the magnitude values in file

nrep

number of replicates for the bootstrap

title

main title for the plot

Value

This function returns a list containing the following components:

quant1

the 5%, 50% and 95% quantiles of the bootstrap replicates for the main discontinuity

valid

the numbers of valid replicates

bmean

the bootstrap mean values

bse

the bootstrap standard-error values

bme

the bootstrap margin of errors values

quant2

the 5%, 50% and 95% quantiles of the bootstrap replicates for the auxiliary discontinuity

Details

This function reads magnitude values in the field which number is indicated by colid in file. The function returns values of significant magnitude discontinuities (e. g. deviations from linearity) in the FMD. A bootstrap procedure is used to obtain the 90% confidence interval for magnitude discontinuities. We assumed the distribution of the nrep bootstrap replicates is not skewed. Therefore, the 90% confidence interval is simply formed by taking 5% and 95% quantiles of the bootstrap replicates as the lower and upper bound of the interval respectively. These values and the 50% quantile (median) are returned in a list by the function. The function also returns bootstrap mean and bootstrap standard-error (standard deviation of bootstrap replicate estimates). The bootstrap margin of errors at the 90% normal confidence level is returned as the result of 1.645 \* bootstrap standard-error. The function produces a plot showing the FMD and histograms of magnitude values for the significant discontinuities in the FMD. The plot is stored into a file with name file\_disc.png (png format file). Values of counts in histograms are controlled by the number of replicates nrep that are used.

References

D. Amorese, "Applying a change-point detection method on frequency-magnitude distributions", Bull. seism. Soc. Am. (2007) 97, doi:10.1785\/0120060181

Examples

fmddisc(file=system.file("extdata","IDYLLdeep.data.txt",package="GRTo"),
header=FALSE,colid=15,nrep=200,"FMD mag discontinuities")