[CEUS-earthquake-hazards] alternative hazard maps

[Seth Stein]

Art,

Thanks for your comments that raise several points.

In terms of the earthquake probabilities, our point
was that time-dependent models predict lower probabilities
and thus hazards. The precise numbers will depend on the
particular model (Poisson, Gaussian, lognormal, Wiebull) and
parameters chosen. For example

recurrence mean +/-
standard deviation years
                         probability % in  next 50 years

500 +/- 100             10      poisson time independent
                         0.44    gaussian time dependent
                         0.02    log normal time dependent

500 +/- 200             10.00   poisson time independent
                         4.04    gaussian time dependent
                         2.88    log normal time dependent

450 +/- 225             11.11   poisson time independent
                         6.07    gaussian time dependent
                         6.86    log normal time dependent

440 +/- 147             11.36   poisson time independent
  (Tuttle                4.73    gaussian time dependent
    values)              3.34    log normal time dependent

My advice to anyone interested is to try various values and
get a feel for the results. I've put a simple spreadsheet
for this, and a general discussion of earthquake probability
issues, on

http://www.earth.northwestern.edu/people/seth/Spreadsheets

In terms of the effect on the hazard map of using the time dependent
models, we tried to set everything else to be the same as the
parameters you used. We were slightly off on the regional background
because we used a different Mblg to Mw conversion. We appreciate your
spotting this and will change it. This won't affect the results
showing the effect of time dependence verus time
independence, since it's just a baseline.


-- 
Seth Stein
William Deering Professor
Department of Earth and Planetary Sciences
1850 Campus Drive
Northwestern University, Evanston, IL 60208
(847) 491-5265 FAX: (847) 491-8060 E-MAIL: seth at earth.northwestern.edu
http://www.earth.northwestern.edu/people/seth