epicentres               package:ssEDA               R Documentation

_E_p_i_c_e_n_t_r_a_l _P_l_o_t _o_f _S_e_l_e_c_t_e_d _E_v_e_n_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Plots earthquake epicentres selected from a given catalogue. The
     colour and size of each point can be made to represent the depth
     and the magnitude of the event, respectively.

_U_s_a_g_e:

     epicentres(events, usr=NA, magnitude=c(-Inf, Inf), cex=NA,
                criteria = TRUE, depth=c(0, Inf),
                colours=c("red2", "yellow2", "green2", "cyan2", "blue2"),
                mapname="world2")

_A_r_g_u_m_e_n_t_s:

  events: defines the events to be plotted. It is an object of class
          '"subset"', '"catalogue"', or '"matrix"'. If of class
          '"subset"', it will generally be created by 'subsetcircle',
          'subsetpolygon', 'subsetrect' or 'subsetsphere'. If of class
          '"matrix"', it must contain the named columns: 'longitude',
          'latitude', 'depth', and 'magnitude'. 

     usr: a vector of length 4 than defines boundary positions of the
          axes, i.e. 'c(xmin, xmax, ymin, ymax)'. The default is
          selected so that the extreme events are just included. 

magnitude: vector of magnitudes, where 'magnitude[i]' is less than or
          equal to 'magnitude[i+1]'. If 'length(magnitude)==2', then
          events with magnitude greater than or equal to 'magnitude[1]'
          and less than 'magnitude[2]' are selected and events are
          plotted as points. If 'length(magnitude)' is greater than 2,
          magnitude defines a sequence of intervals, for which events
          are plotted as circles of increasing size by for increasing
          magnitude. The size of the circles is determined by the 'cex'
          parameter. Default is 'c(-Inf, Inf)'.  

     cex: vector containing the sizes of the plotted points or circles.
          The length of the vector should correspond to the number of
          magnitude intervals defined by the magnitude vector. If
          'length(magnitude)==2', then events will be plotted as points
          and cex will be a scalar denoting the size of the points. If
          'length(magnitude)' is greater than 2, then the events are
          plotted as circles of increasing radius for increasing
          magnitude. The circle radii are proportional to the values
          specified in the 'cex' vector. Default values of 'cex' are
          'seq(0.2, length(magnitude)-1, 0.5)'. These values are
          appropriate for plots with the order of a thousand points,
          but may be too small for 100 or less. 

criteria: logical variable. If 'TRUE' (default) the subsetting
          parameters are printed below the graph. 

   depth: vector of depths, where 'depth[i]' is less than or equal to
          'depth[i+1]'. If 'length(depth)==2', then events with depth
          greater than or equal to 'depth[1]' and less than 'depth[2]'
          are selected. If 'length(depth)' is greater than 2, depth
          defines a sequence of intervals, for which events are plotted
          in the colours specified by the parameter colours. Default is
          'c(0, Inf)'. 

 colours: vector of colours for the different depth intervals. 

 mapname: character string giving the map name. Low resolution maps
          contained in package 'maps' are '"nz"' and '"world2"'
          (default). High resolution maps contained in the package
          'mapdata' are '"nzHires"', '"world2Hires"' and
          '"chinaHires"'. The "2" on '"world2"' denotes the version
          where the longitudes are all positive. 

_D_e_t_a_i_l_s:

     The plot is placed into the current graphics device. If a graphics
     device is not open, one of the default type is opened.

     The plot uses a rectangular projection. The aspect of the plot
     (y/x ratio) is calculated within the function, and is set so that
     the use of the available area within the graphics device is
     maximised. The graphics device remains open at the end of the
     function execution so that additional annotation and points can be
     added to the plot, if required. The margins and aspect ratio will
     also remain in effect at the end of the execution of the function,
     and should be reset if multiple plots are to be written to the
     same output file; see "Examples" below.

_S_e_e _A_l_s_o:

     'depth.hist', 'freq.cusum', 'freq.magnitude', 'magnitude.cusum',
     'magnitude.time', 'threeD', 'timeplot', 'multigraph'

_E_x_a_m_p_l_e_s:

     #   Remember the parameters of the graphics device

     par.reset <- par(no.readonly=TRUE)

     #--------------------------------------------------------------------

     #    Here the data are contained in a matrix

     data <- cbind(latitude=c( -41.70, -39.30, -40.50, -30.62, -28.42, -32.31),
                   longitude=c(172.20,  177.00, 175.50, 178.42, 179.97, 181.21),
                   depth=c(20, 30, 45, 12, 300, 339),
                   magnitude=c(7.8, 7.8, 7.6, 7.4, 7.4, 7.9))

     epicentres(data, usr=c(172, 182, -42, -28), cex=2, mapname="nz")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Here the data are contained in a catalogue

     data(NZ55)

     epicentres(NZ55, mapname="nz")
     title(main="Some Large NZ Events")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     #   Make the Wellington Catalogue
     as.catalogue(subsetrect(NZ, minlat=-42.2, maxlat=-40.5,
                  minlong=173.6, maxlong=176.0, minday=julian(1,1,1978)),
                  catname="Wellington")

     b <- subsetrect(Wellington, minlong=173.6, maxlong=176.0, minlat=-42.1,
                      maxlat=-40.5, mindepth=36, minday=julian(1,1,1988),
                      maxday=julian(1,1,1993))

     #   Note that usr specifies the area in the plot
     epicentres(b, usr=c(b$minlong-0.01, b$maxlong+0.01,
                         b$minlat-0.005, b$maxlat+0.005),
                depth=c(36, 50, 70, 100, 150, Inf), criteria=FALSE,
                magnitude=c(2, 3, 4, 5, 6, Inf), mapname="nz")
     title(sub=expression(paste("Depth (km):  ", 36 <= {red < {50 <= 
           {yellow < {70 <= {green < {100 <= {cyan < {150 <= {blue <
           infinity}}}}}}}}})), line=3)
     title(main="Wellington Catalogue:  Deep Events")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     b <- subsetrect(Wellington, minlong=173.6, maxlong=176.0, minlat=-42.1,
                      maxlat=-40.5, maxdepth=35.99, minday=julian(1,1,1988),
                      maxday=julian(1,1,1993))

     #   Note that usr specifies the area in the plot
     epicentres(b, usr=c(b$minlong-0.01, b$maxlong+0.01,
                         b$minlat-0.005, b$maxlat+0.005),
                depth=c(0, 10, 15, 20, 25, 36), criteria=FALSE,
                magnitude=c(2, 3, 4, 5, 6, Inf), mapname="nz")
     title(sub=expression(paste("Depth (km):  ", 0 <= {red < {10 <= 
           {yellow < {15 <= {green < {20 <= {cyan < {25 <= {blue < 36}}}}}}}}})),
           line=3)
     title(main="Wellington Catalogue:  Shallow Events")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     b <- subsetrect(NZ, minlong=166, maxlong=180, minlat=-48,
                      maxlat=-34, minmag=3, minday=julian(1,1,1970),
                      maxday=julian(1,1,1993), mindepth=36)

     epicentres(b, depth=c(36, 70, 100, 140, 200, Inf), criteria=FALSE,
                usr=c(b$minlong, b$maxlong, b$minlat, b$maxlat), mapname="nz")
     title(sub=expression(paste("Depth (km):  ", 36 <= {red < {70 <= 
           {yellow < {100 <= {green < {140 <= {cyan < {200 <= {blue <
           infinity}}}}}}}}})), line=3, cex.sub=0.95)
     title(main="NZ Catalogue:  Deep Events")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     b <- subsetcircle(NZ, centrelong=176.8, centrelat=-37.8,
                        minmag=3, minday=julian(1,1,1987),
                        maxday=julian(1,1,1988), maxradius=100)

     epicentres(b, cex=1.3, mapname="nz")
     title(main="Edgecumbe Earthquake")
     par(par.reset)

     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     b <- subsetcircle(NZ, centrelong=177.5, centrelat=-37,
                        minmag=3, minday=julian(1,1,1984),
                        maxday=julian(1,1,1986), maxradius=100)

     epicentres(b, cex=1.5, mapname="nz")
     title(main="Bay of Plenty Swarm")
     par(par.reset)
         
     #--------------------------------------------------------------------

     #    Requires the NZ Catalogue
     require(ssNZ)

     b <- subsetcircle(NZ, centrelong=176.4, centrelat=-40.4,
                        minmag=3, minday=julian(1,1,1990),
                        maxday=julian(1,1,1991), maxradius=50)

     epicentres(b, cex=1.5, mapname="nz")
     title(main="Weber (Dannevirke) Earthquake")
     par(par.reset)

