Download Earthquakes The Earth is covered by tectonic plates which slide past

Earthquakes
The Earth is covered by tectonic plates which slide past or over/under one
another.
The sliding motion is jerky because of friction.
The interface jams and stress builds up.
The stored elastic energy is suddenly released in an earthquake, which is
usually followed by aftershocks.
Gutenberg-Richter Law
log10 N = a − bM
M is the magnitude of the quake
M ∼ log(M0)
M0 is the seismic moment
M0 = µSD
D is the displacement of the fault in the quake
S is the area of the fault
µ is the shear modulus or rigidity of the rocks in fault
N (M ) is the number of quakes with magnitude > M
Outline of quake.py
path to gnuplot executable
define a function to linear fit x-y data without error bars
data downloaded from
http://neic.usgs.gov/neis/epic/epic_global.html
store event data in a python dictionary object with
key = magnitude starting in column 50
value = number of events with this magnitude
x data = M values sorted in increasing order
y data = log10(N ) where N = number of events with magnitude >= M
perform a least square fit
write histogram data to file
Gnuplot commands to plot histogram
create a script file and call Gnuplot
Python Dictionaries in quake.py
Earthquake date are stored in a dictionary with magnitude M as key and
number of quakes with this magnitude as value
Read M from the current event line in the data file
Attempt to increment the number of quakes with this M
If the attempt fails, handle the exception
Python dictionary tutorial: http://docs.python.org/tutorial/
datastructures.html#dictionaries
Python exceptions tutorial:
http://docs.python.org/tutorial/errors.html
Very important: N (M ) in the Gutenberg-Richter law is NOT the number
of events with magnitude M