Source code for openquake.hmtk.plotting.seismicity.max_magnitude.cumulative_moment

#!/usr/bin/env python
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'''
Module to produce cumulative moment plot
'''


import numpy as np
import matplotlib.pyplot as plt


def plot_cumulative_moment(year, mag):
    '''Calculation of Mmax using aCumulative Moment approach, adapted from
    the cumulative strain energy method of Makropoulos & Burton (1983)
    :param year: Year of Earthquake
    :type year: numpy.ndarray
    :param mag: Magnitude of Earthquake
    :type mag: numpy.ndarray
    :keyword iplot: Include cumulative moment plot
    :type iplot: Boolean
    :return mmax: Returns Maximum Magnitude
    :rtype mmax: Float
    '''
    # Calculate seismic moment
    m_o = 10. ** (9.05 + 1.5 * mag)
    year_range = np.arange(np.min(year), np.max(year) + 1, 1)
    nyr = np.int(np.shape(year_range)[0])
    morate = np.zeros(nyr, dtype=float)
    # Get moment release per year
    for loc, tyr in enumerate(year_range):
        idx = np.abs(year - tyr) < 1E-5
        if np.sum(idx) > 0:
            # Some moment release in that year
            morate[loc] = np.sum(m_o[idx])
    ave_morate = np.sum(morate) / float(nyr)

    # Average moment rate vector
    exp_morate = np.cumsum(ave_morate * np.ones(nyr))

    plt.step(year_range, np.cumsum(morate), 'b-', linewidth=2)
    plt.plot(year_range, exp_morate, 'r-', linewidth=2)
    # Get offsets
    upper_morate = exp_morate + (np.max(np.cumsum(morate) - exp_morate))
    lower_morate = exp_morate + (np.min(np.cumsum(morate) - exp_morate))
    plt.plot(year_range, upper_morate, 'r--', linewidth=1)
    plt.plot(year_range, lower_morate, 'r--', linewidth=1)
    plt.axis([np.min(year), np.max(year), 0.0, np.sum(morate)])