EventRate Cookbook

The EventRate class is for making plots of:

number of events per unit time (often called "counts")
energy release rate / cumulative magnitude per unit time

Simple EventRate example
Event rates for overlapping time windows
Plots of other event rate metrics
Other plot types

Simple EventRate example

First we create a Catalog object from the Redoubt dataset

dbpath = fullfile(TESTDATA, 'css3.0', 'avodb200903');
redoubtLon = -152.7431;
redoubtLat = 60.4853;
maxR = km2deg(20.0);
catalogObject = Catalog.retrieve('antelope', 'dbpath', dbpath, ...
	'radialcoordinates', [redoubtLat redoubtLon maxR]);

Loading data from /home/t/thompsong/src/GISMO.website/testdata/css3.0/avodb200903
Got 1397 events

For a quick plot of earthquakes per hour, we create an EventRate object and then plot it. Here our binsize is 1/24 days, i.e. 1 hour.

eventrateObject = catalogObject.eventrate('binsize', 1/24);
eventrateObject.plot()

Change to a smaller bin size of 20 minutes:

eventrateObject = catalogObject.eventrate('binsize', 20/1440);
plot(eventrateObject);

Note that

eventrateObject.plot()

and

plot(eventrateObject)

do exactly the same thing. The first is the object-oriented style OBJECT.METHOD(INPUT PARAMETERS), the second is the functional style FUNCTION(OBJECT, INPUT PARAMETERS). The object oriented style is preferable.

Event rates for overlapping time windows

Sometimes it is desirable to compute event rate metrics for sliding - i.e. overlapping - time windows. This is easily done with the 'stepsize' parameter. If omitted, stepsize defaults to the binsize - which is the length of the time window. So in the previous example, both binsize and stepsize were 1.0 hours. But we can just as easily compute an EventRate object for the same EventRate object with a binsize of 1 hour, and stepsize of 1 minute. This effectively converts a Catalog into a set of continuous metrics, measured every minute, directly comparable to 1-minute RSAM.

eventrateObject = catalogObject.eventrate('binsize', 1/24,  'stepsize', 1/1440);
eventrateObject.plot()

Plots of other event rate metrics

eventrateObject.plot()

is equivalent to typing:

eventrateObject.plot('metric', 'counts');

The full list of metrics that can be plotted are:

counts
mean_rate
median_rate
cum_mag
mean_mag
median_mag
energy

All of these are properties of an EventRate object except for energy, which is computed from cum_mag on-the-fly. Several can be plotted at once in subplots of the same figure using a cell array:

eventrateObject.plot('metric', {'mean_rate'; 'median_rate'; 'mean_mag'; 'cum_mag'});

They can of course be plotted in separate figure windows:

eventrateObject.plot('metric', 'mean_rate')
eventrateObject.plot('metric', 'median_rate')
eventrateObject.plot('metric', 'mean_mag')
eventrateObject.plot('metric', 'cum_mag')