get.corner {RSEIS}

Get Corner Frequency: Linear Model

Description

Search for low frequency asymptote, corner frequency, and fall off slope of seismic spectrum.

Usage

get.corner(INfreq, INspec, dt, f1, f2, PLOT = FALSE, VERBOSE = FALSE)

Arguments

INfreq

frequency vector

INspec

spectrum

dt

deltaT

f1

low frequency for modeling, Hz

f2

High frequency for modeling, Hz

PLOT

logical, TRUE=plot

VERBOSE

TRUE=diagnostics

Details

This routine does not assume any particular mathematical model. It searches for a three parameters that describe two lines that mimic the displacement spectrum. The search is done via least squares.

Value

Model of 3 parameters, best fit.

Author(s)

Jonathan M. Lees<jonathan.lees.edu>

See Also

brune.doom

Examples

data(CE1)

##   set frequency range for modeling for this high frequency data
##   we use f2 = 50, but for volcano data should be f2<15

f1 <- 0.01
f2 <- 50.0  

##  set up data and parameters
amp <-  CE1$y
len2 <- 2*next2(length(amp))
a <- list(y=amp, dt=CE1$dt)

Spec <- MTMdisp(a, f1=f1, f2=f2, len2=len2, PLOT=FALSE )

lspec <- Spec$displ

###  get initial estimate of parameters
xc <- get.corner(  Spec$f , lspec, CE1$dt, f1, f2, PLOT=FALSE)