5.10.1.3. eqcorrscan.utils.mag_calc.calc_b_value¶
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eqcorrscan.utils.mag_calc.
calc_b_value
(magnitudes, completeness, max_mag=None, plotvar=True)[source]¶ Calculate the b-value for a range of completeness magnitudes.
Calculates a power-law fit to given magnitudes for each completeness magnitude. Plots the b-values and residuals for the fitted catalogue against the completeness values. Computes fits using numpy.polyfit, which uses a least-squares technique.
Parameters: Return type: list
Returns: List of tuples of (completeness, b-value, residual, number of magnitudes used)
Example
>>> from obspy.clients.fdsn import Client >>> from obspy import UTCDateTime >>> from eqcorrscan.utils.mag_calc import calc_b_value >>> 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.magnitudes[0].mag for event in catalog] >>> b_values = calc_b_value(magnitudes, completeness=np.arange(3, 7, 0.2), ... plotvar=False) >>> round(b_values[4][1]) 1.0 >>> # We can set a maximum magnitude: >>> b_values = calc_b_value(magnitudes, completeness=np.arange(3, 7, 0.2), ... plotvar=False, max_mag=5) >>> round(b_values[4][1]) 1.0