Preferred Rupture Directivity in Hazard Curve Computations

Notice: This page is still under construction. TODO statements indicate areas still under work.

This page documents efforts to investigate the impact that preferred rupture directions would have on hazard as calculated with CyberShake ground motions in OpenSHA.

Research Plan

There is some evidence that some faults have a preferred rupture direction. To investigate the impact this could have on hazard, we'll identify a handful of faults, modify the probabilities of individual rupture variations to favor those at the preferred end of the fault, and generate new hazard products with the modified probabilities. No new ground motions will need to be calculated; we'll use Study 22.12 and 24.8 ground motions.

Below is a flow chart representing the steps involved in performing this work.

Implementation Details

With the UCERF2 ERF used in Study 22.12 and Study 24.8, probabilities are specified at the rupture level -- that is, for a specific fault segment(s) and magnitude. We then divide the probability by the number of rupture variations to get the uniform probability of each rupture variation. For this work, we will create modified rupture variation probabilities and use these to generate a modified hazard curve.

We will add new functionality to the CyberShake-related code in OpenSHA to support this work. OpenSHA has a defined interface to return a list of probabilities for a given source ID and rupture ID. We'll specify the source ID, rupture ID, rupture variation ID, probability in a CSV file which will be passed to OpenSHA. This file will be parsed and used to populate a data structure, which will then be accessed by an implementation of the interface to determine the new probabilities. For any source ID, rupture ID, rupture variation ID combinations not in the file, we'll use the default UCERF2 probabilities. Then the new probabilities will be used to create a hazard curve.

Modifying the HazardCurvePlotter to allow us to input custom probabilities for rupture variations allows us to compare hazard expected for persistent directivity vs random rupture direction. We can prescribe directivity based on topography or physics reasons and see if the signature is drowned out by randomness of the network or if it still stands out.

New Functionality

The existing OpenSHA command-line tool, HazardCurvePlotter, is able to compute hazard curves and plot them to images locally on a system. We’ve added a new parameter, rv-probs-csv, for a Rupture Variation Probabilities Input CSV file.

Passing this file allows a user to specify directivity for specific rupture variations. Previously, all variations had an equal probability, distributed from the probability of the rupture itself. The sum of probabilities of the variations must still sum to the probability of the corresponding rupture.

Curves with modified probabilities are not cached to the CyberShake database by default. It takes me approximately 4 minutes to compute hazard curves for just period 3 locally on my system. It takes about 33 minutes to compute for periods 2, 3, 5, and 10.

CSV Files

CSV Structure

The input CSV file should have the following columns.

• Source_ID
• Rupture_ID
• Rup_Var_ID
• Probability

The specified source and rupture acts as a composite key, uniquely identifying a rupture variation. Each rupture at a site is comprised of a set of rupture variations. The CSV file does not need to have an entry for each variation found in the CyberShake database. The remaining unspecified variations are given an equal probability distributed from the difference of the rupture probability and the sum of rupture variation probabilities specified. The formatting, structure, and sum or probabilities are validated in the HazardCurvePlotter.

CSV Generation

TODO: See some examples of input CSVs here.

TODO: The commands utilizing these CSVs and the corresponding runs are found

Plots

The following plots show curves for the following sites:

• ALP
• USC
• SBSM
• SVD
• PDE

All are plotted with periods of 2, 3, 5, and 10 seconds. The modified probabilities are such that the hypocenters are responsible for 90% of the probability, unless otherwise specified.

TODO: Add comparison 90p plots (1 for each period), overlay reference, and thoughts on impact of modified probabilities overall.

TODO: Explain where comparison plot was made (Excel) and potential to expand existing OpenSHA Comparison Plot functionality for this purpose.

USC 9306 (10p)

Unlike with other plots, the hypocenters are responsible for 10% of the probability.

TODO: Add individual plot

Compute Time: 33.15 min

Command Parameters:

-o src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/3  \

-R 9306 \

-cmp RotD50 \

-rv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/USC_mod_probs_Mojave_Coachella.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

-t TXT,PDF \

-p 2,3,5,10

USC 9306

TODO: Add individual plot

TODO: Add compute time.

Command Parameters:

--output-dir src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/USC  \

--run-id 9306 \

--component RotD50 \

--period 2,3,5,10 \

--rv-probs-csv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/USC_mod_probs_Mojave_Coachella_90p.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

--type TXT,PDF

ALP 9542

TODO: Add individual plot

TODO: Add compute time.

Command Parameters:

--output-dir src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/ALP  \

--run-id 9542 \

--component RotD50 \

--period 2,3,5,10 \

--rv-probs-csv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/ALP_mod_probs_Mojave_Coachella_90p.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

--type TXT,PDF

SBSM 9320

TODO: Add individual plot

TODO: Add compute time.

Command Parameters:

--output-dir src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/SBSM  \

--run-id 9320 \

--component RotD50 \

--period 2,3,5,10 \

--rv-probs-csv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/SBSM_mod_probs_Mojave_Coachella_90p.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

--type TXT,PDF

SVD 9647

TODO: Add individual plot

TODO: Add compute time.

Command Parameters:

--output-dir src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/SVD  \

--run-id 9647 \

--component RotD50 \

--period 2,3,5,10 \

--rv-probs-csv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/SVD_mod_probs_Mojave_Coachella_90p.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

--type TXT,PDF

PDE 9663

TODO: Add individual plot

TODO: Add compute time.

Command Parameters:

--output-dir src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/modprob/PDE  \

--run-id 9663 \

--component RotD50 \

--period 2,3,5,10 \

--rv-probs-csv src/test/resources/org/opensha/sha/cybershake/plot/HazardCurvePlotter/PDE_mod_probs_Mojave_Coachella_90p.csv \

--plot-chars-file src/main/resources/org/opensha/sha/cybershake/conf/robPlot.xml \

--type TXT,PDF