| decluster.M8 {ssM8} | R Documentation |
The function reads an earthquake catalogue (with class "catalogue"), deletes events with magnitude below a cutoff level and all aftershocks, optionally deletes events with depth too deep or too shallow, and counts the number of aftershocks in the 14 days following each remaining mainshock. The output is also a "catalogue" object containing the mainshock information and an additional variable with the corresponding number of aftershocks.
decluster.M8(catalogue, cutoff.mag=4, minday=min(catalogue$time),
mindepth= - Inf, maxdepth=Inf, debug=FALSE, decluster.name="",
magn.window = c(3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8),
space.window = c(30, 40, 40, 40, 50, 50, 50, 100, 100, 150, 200),
time.window = c(6, 11, 23, 46, 91, 183, 183, 365, 730, 913, 1096))
catalogue |
the catalogue. It should be a "catalogue" object.
|
decluster.name |
character string containing the name of the declustered catalogue. |
cutoff.mag |
the magnitude below which the record is cutoff before going through the mainshock-aftershock separation. Default 4.0. |
minday |
number of days from 1 January 1970 (julian). If specified, then after mainshocks have been separated out, mainshocks before this date are dropped. If not specified, no mainshocks are dropped. |
mindepth |
all events with depth less than mindepth are deleted before entering algorithm. Default is -Inf.
|
maxdepth |
all events with depth greater than or equal to maxdepth are deleted before entering algorithm. Default is Inf.
|
magn.window |
a vector giving the magnitude window boundaries. The default c(3, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0).
|
time.window |
a vector giving the time window boundaries (days). The default is c(6, 11, 23, 46, 91, 183, 183, 365, 730, 913, 1096).
|
space.window |
a vector giving the space window boundaries (km). The default is c(30, 40, 40, 40, 50, 50, 50, 100, 100, 150, 200).
|
debug |
boolean; default is FALSE.
|
All events with magnitude less than magn.window[1] are assumed to have no aftershocks. Those events with magnitude less than magn.window[i+1] but greater than or equal to magn.window[i] have aftershock time and space windows given by time.window[i] and space.window[i] respectively, for i = 1, ..., length(magn.window)-1. All events with magnitude greater than or equal to magn.window[length( magn.window)] have aftershock time and space windows given by time.window[length(magn.window)] and
newline space.window[length(magn.window)] respectively.
The value returned is the vector identifying the mainshock to which each aftershock belongs. The mainshocks themselves are identified by zeros.
A "catalogue" object with name given by the argument decluster.name is written to the session workspace. It contains the mainshock hypocentral information and an additional variable, n.aftershocks, containing the number of aftershocks following the mainshock within 14 days.
Li Dongfeng, 1997; modified November 1999
M8, M8.series, M8.TIP,
plot.M8
# Requires the package ssNZ
require(ssNZ)
as.catalogue(subsetrect(NZ, minday=julian(1,1,1965),
maxday=julian(1,1,2000), minmag=4.5),
catname="NZ45")
decluster.M8(NZ45, cutoff.mag=4.5, decluster.name="NZ.mainshocks")
print(summary(NZ.mainshocks))