[Seisunix] Modeling Covid-19 with Seismic Unix

Cemal Erdemir cerdemir at hotmail.com
Mon Apr 6 23:10:37 CEST 2020

Hi Dominique,

I am an intense SU user, and a CSM-Geop graduate, I would like to have an account.
I put a paper together using SU package, it was  published two years ago by Istanbul Uni. publication resources.

We are fine for now in Houston, TX.


Cemal Erdemir
Email:  cerdemir at hotmail.com
Cell:    +1 832 668 6289
Office: +1 281 858 7653

From: Seisunix <seisunix-bounces at mailman.seismic-unix.org> on behalf of Dominique ROUSSET <dominique.rousset at univ-pau.fr>
Sent: Monday, April 6, 2020 2:18 AM
To: seisunix at mailman.seismic-unix.org <seisunix at mailman.seismic-unix.org>
Subject: Re: [Seisunix] Modeling Covid-19 with Seismic Unix

Hi John,

SU is definitely full of unknown resources !!!

I hope everyone is as fine as possible, in these difficult times...

Don't forget that wiki.seismic-unix.org needs contributions !!!!
Ask me for an account to write in the wiki...

Le 05/04/2020 à 20:38, John Stockwell a écrit :

I send my good wishes to all of you and I hope that you, your families, and your friends are faring well in this difficult time.

For those who are interested in modeling populations, such as the current epidemic, there is a logistic equation solver called
“verhulst” in the SU package which you may find of interest.

For example for Covid-19 cases in the US, taking 22 January as day 0 of cases in the US and 29 February as day 0 for deaths. Respective
stepmax= values of 72 for cases and 34 for deaths are both 3 April

verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=x > calculated_cases.bin

verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=x > calculated_deaths.bin

xgraph < calculated_cases.bin n=72 nplot=1 d1=1 &

xgraph < calculated_deaths.bin n=34 nplot=1 d1=1 &

The growth rate a1 values are determined empirically from publicly available data, in this case from the CDC and from the Worldometer site. You will have to make your own estimate of a1 for the data that you are modeling.

Another parameter that is harder to get is an estimate of the carrying capacity of the system a2. Here I am assuming a maximum of 1 million cases in the US and 100 thousand deaths.

The number of new cases or deaths per day is measured by the derivative of the solutions to the verhulst equation

verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=y > delta_cases.bin

verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=y > delta_deaths.bin

xgraph < delta_cases.bin n=72 nplot=1 d1=1 &

xgraph < delta_deaths.bin n=34 nplot=1 d1=1 &

The peak in the change of the population per day occurs when the population reaches the exactly half of the carrying capacity of the system. Thus, raising the carrying capacity will increase the height of the peak and move it out later in time.

Take care, everyone and stay safe.


John Stockwell
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|Dominique Rousset           LFCR UMR5150 / E2S UPPA / Dpt des géosciences|
|Univ. Pau et des Pays de l'Adour BP 1155       F-64013 Pau Cedex - France|
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