Uniform Hazard Spectra Values

[jdadr...@up.edu.ph]

Hi everyone,

I have been working on a PSHA for my Thesis and I am currently having a problem with my output. I created my source model and made sure the format is correct.

The curves of the UHS with a PoE of 2% are reaching 2.0g which is too high when the expected value is around 1.5g. I am not sure which parameter I am missing or which parameters directly affect the UHS. 

I also want to know which python files contain the formulas and calculations. 

[Marco Pagani]

The hazard results reflects what you have in your input so that where you should start from.
You find the OQ Engine hazard curve calculator here: https://github.com/gem/oq-engine/blob/master/openquake/hazardlib/calc/hazard_curve.py

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[Joseph Jedidiah Adriano]

Thank you very much. I tried using background seismicity as a multipoint source and area source separately and I notice their values differ with the calculations using a multipoint source has a higher value.

On the left is the source as a Multipoint and on the right is as an Area source.

Both calculations have the same parameters, including the a values.  

To view this discussion on the web visit https://groups.google.com/d/msgid/openquake-users/863D52EA-1FBF-440B-A92D-734EA49398BA%40globalquakemodel.org.

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-"Jed"

Joseph Jedidiah D. Adriano

2014-22349

SAIS: 10061575

BS Civil Engineering

[Shreyasvi C]

Dear Joseph,

Please check if your source model file is compliant with the necessary format using the demo calc. Also, the UHS for the area source (I think), POE = 0.02 is less than that of POE = 0.10. I suspect a calculation error, so please check the input files. Additionally, It would be useful to check the input parameters defined in your job file. Example: Truncation level and the reference Vs(30). the hazard estimated for a truncation level of 3 will be naturally higher. Also, you are estimating for a lower Vs(30) so you can expect higher amplification. Make sure your expected value of 1.5g is corresponding to these inputs. 

For future reference, specify `reference_depth_to_2pt5km_per_sec` in km and `reference_depth_to_1pt0km_per_sec` in meters. 

Hope these suggestions help in resolving your issue. 

Regards,

Shreyasvi

[komlofske...@gmail.com]

Oh yeah I can find the correct calculations here. I've done this a time or two.

Sent from Yahoo Mail on Android

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