56 lines
2.1 KiB
Matlab
56 lines
2.1 KiB
Matlab
% [m,T]=Ret_periodGRU(Md,Mu,dM,Mmin,lamb,eps,b)
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%
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% EVALUATES THE MEAN RETURN PERIOD VALUES USING THE UNLIMITED G-R LED
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% MAGNITUDE DISTRIBUTION MODEL.
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%
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% AUTHOR: Stanislaw. Lasocki, Institute of Geophysics Polish Academy of
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% Sciences, Warsaw, Poland
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%
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% DESCRIPTION: The assumption on the unlimited Gutenberg-Richter relation
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% leads to the exponential distribution model of magnitude distribution
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% from and above the catalog completness level Mmin. The shape parameter of
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% this distribution and consequently the G-R b-value are calculated at
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% start-up of the stationary hazard assessment services in the
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% unlimited Gutenberg-Richter estimation mode.
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%
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% The mean return period of magnitude M is the average elapsed time between
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% the consecutive earthquakes of magnitude M.
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% The mean return periods are calculated for magnitude starting from Md up
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% to Mu with step dM.
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%
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%INPUT:
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% Md - starting magnitude for return period calculations
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% Mu - ending magnitude for return period calculations
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% dM - magnitude step for return period calculations
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% Mmin - lower bound of the distribution - catalog completeness level
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% lamb - mean activity rate for events M>=Mmin
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% eps - length of the round-off interval of magnitudes.
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% b - Gutenberg-Richter b-value
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%
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%OUTPUT:
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% m - vector of independent variable (magnitude) m=(Md:dM:Mu)
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% T - vector od mean return periods of the same length as m
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%
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% LICENSE
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% This file is a part of the IS-EPOS e-PLATFORM.
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%
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% This is free software: you can redistribute it and/or modify it under
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% the terms of the GNU General Public License as published by the Free
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% Software Foundation, either version 3 of the License, or
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% (at your option) any later version.
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%
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% This program is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details, <http://www.gnu.org/licenses/>.
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%
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function [m,T]=Ret_periodGRU(Md,Mu,dM,Mmin,lamb,eps,b)
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if Md<Mmin; Md=Mmin;end
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m=(Md:dM:Mu)';
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beta=b*log(10);
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T=1/lamb./exp(-beta*(m-Mmin+eps/2));
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end
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