obspy.signal.invsim.estimate_magnitude

estimate_magnitude(paz, amplitude, timespan, h_dist)[source]

Estimates local magnitude from poles and zeros of given instrument, the peak to peak amplitude and the time span from peak to peak. Readings on two components can be used in magnitude estimation by providing lists for paz, amplitude and timespan.

Parameters:
  • paz PAZ of the instrument [m/s] or list of the same
  • amplitude Peak to peak amplitude [counts] or list of the same
  • timespan Timespan of peak to peak amplitude [s] or list of the same
  • h_dist Hypocentral distance [km]
Returns:

Estimated local magnitude Ml

Note

Magnitude estimation according to Bakun & Joyner, 1984, Eq. (3) page 1835. Bakun, W. H. and W. B. Joyner: The Ml scale in central California, Bull. Seismol. Soc. Am., 74, 1827-1843, 1984

Example

>>> paz = {'poles': [-4.444+4.444j, -4.444-4.444j, -1.083+0j],
...        'zeros': [0+0j, 0+0j, 0+0j],
...        'gain': 1.0, 'sensitivity': 671140000.0}
>>> mag = estimate_magnitude(paz, 3.34e6, 0.065, 0.255)
>>> print(round(mag, 6))
2.132873
>>> mag = estimate_magnitude([paz, paz], [3.34e6, 5e6], [0.065, 0.1],
...                          0.255)
>>> print(round(mag, 6))
2.347618