create data for a scatter plot of aftershocks from the Magna, UT earthquake on 2020-03-18

aftershocks.rb

require 'date'
require 'net/http'

QUERY = "https://earthquake.usgs.gov/fdsnws/event/1/query?format=text&latitude=40.751&longitude=-112.078&maxradiuskm=50&starttime=2020-03-18"
data = Net::HTTP.get(URI(QUERY)).lines
header = data.shift.split('|')
ts_col = header.index("Time")
raise "Time column not found" unless ts_col
mag_col = header.index("Magnitude")
raise "Magnitude column not found" unless mag_col

x = []
y = []
min_date = nil

data.each do |line|
  line = line.split('|')
  y << line[mag_col].to_f
  ts = DateTime.parse(line[ts_col])
  x << ts
  min_date = [min_date, ts].compact.min
end

x = x.map { |ts| "%.3f" % ((ts - min_date) * 24).to_f }
y = y.map { |mag| "%.3f" % mag }

output = StringIO.new
output.puts "hours since quake,magnitude"
x.each_with_index do |ts, i|
  magnitude = y[i]
  output.puts "#{ts},#{magnitude}"
end

IO.popen('pbcopy', 'r+') do |clipboard|
  clipboard.puts output.string
end

puts "#{data.size} data points copied for scatterplot.online"