5.11.1.4. eqcorrscan.utils.plotting.freq_mag

eqcorrscan.utils.plotting.freq_mag(magnitudes, completeness, max_mag, binsize=0.2, save=False, savefile=None)[source]

Plot a frequency-magnitude histogram and cumulative density plot.

Currently this will compute a b-value, for a goiven completeness. B-value is computed by linear fitting to section of curve between completeness and max_mag.

Parameters:
  • magnitudes (list) list of float of magnitudes
  • completeness (float) Level to compute the b-value above
  • max_mag (float) Maximum magnitude to try and fit a b-value to
  • binsize (float) Width of histogram bins, defaults to 0.2
  • save (bool) False will plot to screen, true will save plot and not show to screen.
  • savefile (str) Filename to save to, required for save=True
Returns:

matplotlib.figure.Figure

Note

See eqcorrscan.utils.mag_calc.calc_b_value() for a least-squares method of estimating completeness and b-value. For estimating maximum curvature see eqcorrscan.utils.mag_calc.calc_max_curv().

Example

>>> from obspy.clients.fdsn import Client
>>> from obspy import UTCDateTime
>>> from eqcorrscan.utils.plotting import freq_mag
>>> client = Client('IRIS')
>>> t1 = UTCDateTime('2012-03-26T00:00:00')
>>> t2 = t1 + (3 * 86400)
>>> catalog = client.get_events(starttime=t1, endtime=t2, minmagnitude=3)
>>> magnitudes = [event.preferred_magnitude().mag for event in catalog]
>>> freq_mag(magnitudes, completeness=4, max_mag=7) 

(Source code, png, hires.png)

../../_images/eqcorrscan-utils-plotting-freq_mag-1.png