Earthquakes Over the Past 7 Days

November 29, 2012
By

(This article was first published on Statistical Research » R, and kindly contributed to R-bloggers)

This is a brief example using the maps in R and to highlight a source of data.  This is real-time data and it comes from the U.S. Geological Society.  This shows the location of earthquakes with magnitude of at least 1.0 in the lower 48 states.

```
library(maps)
library(maptools)
library(rgdal)

plot.new()
my.map <- map("state", interior = FALSE, plot=F)
x.lim <- my.map\$range[1:2]; x.lim[1] <- x.lim[1]-1; x.lim[2] <- x.lim[2]+1;
y.lim <- my.map\$range[3:4]; y.lim[1] <- y.lim[1]-1; y.lim[2] <- y.lim[2]+1;
map("state", interior = FALSE, xlim=x.lim, ylim=y.lim)
map("state", boundary = FALSE, col="gray", add = TRUE)
title("Magnitude 1+ Earthquakes Over the Past 7 Days")

eq\$mag.size <- NULL
eq\$mag.size[eq\$Magnitude>=1 & eq\$Magnitude<2] <- .75
eq\$mag.size[eq\$Magnitude>=2 & eq\$Magnitude<3] <- 1.0
eq\$mag.size[eq\$Magnitude>=3 & eq\$Magnitude<4] <- 1.5
eq\$mag.size[eq\$Magnitude>=4] <- 2.0

eq\$mag.col <- NULL
eq\$mag.col[eq\$Magnitude>=1 & eq\$Magnitude<2] <- 'blue'
eq\$mag.col[eq\$Magnitude>=2 & eq\$Magnitude<3] <- 'green'
eq\$mag.col[eq\$Magnitude>=3 & eq\$Magnitude<4] <- 'orange'
eq\$mag.col[eq\$Magnitude>=4] <- 'red'

points(x=eq\$Lon,y=eq\$Lat,pch=16,cex=eq\$mag.size, col=eq\$mag.col)
eq\$magnitude.text <- eq\$Magnitude
eq\$magnitude.text[eq\$Magnitude<4] <- NA

legend('bottomright',c('M 1-2','M 2-3','M 3-4','M4+'), ncol=2,
pch=16, col=c('blue','green','orange','red'))
box()

```

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