Edward (Ned) Field USGS, Pasadena plus

1. OpenSHA Community Tools for Seismic-Hazard Analysis Edward (Ned) Field USGS, Pasadena plus Tom Jordan, Nitin Gupta, Vipin Gupta, Phil Maechling, Allin Cornell, Ken Campbell, Sid Hellman, & Steve Rock

2. Status of Seismic Hazard Analysis (SHA) SHA needs a more physics-based approach to modeling. Lack of consensus on how to construct more physics-based models means we’ll have multiple options. All viable models need to be considered for “proper” SHA (SSHAC Report, 1995). SHA therefore needs a computational infrastructure capable of handling a potentially great number of arbitrarily complex models (a “Community Modeling Environment”).

3. What is SHA? Goal of Seismic Hazard Analysis: The probability that some “Intensity-Measure Type” (e.g., PGA, SA) will exceed a specified “Intensity-Measure Level” (e.g., 0.5 g)

4. Intensity-Measure Relationship (IMR) • Earthquake-Rupture Forecast (ERF) • Probability of all possible • fault-rupture events (M≥~5) • for region & time period Gives IM exceedance probability at a site for a given fault-rupture event Attenuation Relationships (traditional) (no physics) Full-Waveform Modeling (developmental) (more physics) What is SHA? Two main model components:

5. The model used in our National Hazard Maps assumes that each earthquake rupture is completely independent of all others (including the previous one at the exact same location). • Earthquake-Rupture Forecast • Probability of all possible • fault-rupture events (M≥~5) • for region & time period But, others see time-dependent effects and interactions: (Stein & Others) Why SHA needs more physics: Two main model components: However, there is no consensus on how to build these types of models. Thus, SCEC has a working group (RELM) that is developing a variety of viable physics-based models (see www.RELM.org).

6. Inherent limits with respect to accuracy (SCEC Phase III report). Why SHA needs more physics: Two main model components: Intensity-Measure Relationship Gives IM exceedance probability at a site for a given fault-rupture event Attenuation Relationships (traditional) (no physics) Lack of physics can lead to non-physical results (e.g., PGA increasing indefinitely with exposure time).

7. Full-Waveform Modeling (developmental) (more physics) Why SHA needs more physics: Two main model components: Intensity-Measure Relationship Gives IM exceedance probability at a site for a given fault-rupture event Potentially more accurate. However, still developmental due to limited structural knowledge and computational demands. SCEC is working on this (e.g., Pathway II of ITR collaboration).

8. Full-Waveform Modeling (developmental) (more physics) Why SHA needs more physics: Two main model components: Intensity-Measure Relationship Gives IM exceedance probability at a site for a given fault-rupture event For now, NGA is developing a variety of these (no consensus here either), including constraints from simulations (hybrids). Attenuation Relationships (traditional) (no physics)

9. Status of Seismic Hazard Analysis (SHA) SHA needs a more physics-based approach to modeling. Lack of consensus on how to construct more physics based models means we’ll have multiple options. NGA RELM e.g., SCEC ITR “Pathway II”

10. Status of Seismic Hazard Analysis (SHA) SHA needs a more physics-based approach to modeling. Lack of consensus on how to construct more physics based models means we’ll have multiple options. All viable models need to be considered for “proper” SHA (SSHAC Report, 1995).

11. an exception: (Stein & Others) What’s the problem getting multiple, physics-based models into the analysis (why hasn’t it happened)? 1) Geophysicists are comfortable building models and making predictions, but uncomfortable recommending use of them until they’re properly tested and validated. critics say this is premature (we don’t yet know enough)

12. What’s the problem getting multiple, physics-based models into the analysis (why hasn’t it happened)? 1) Geophysicists are comfortable building models and making predictions, but uncomfortable recommending use of them until they’re properly tested and validated. But practitioners can’t wait. They have to make informed decisions today, and need to use whatever models are available.

13. What’s the problem getting multiple, physics-based models into the analysis (why hasn’t it happened)? 1) Geophysicists are comfortable building models and making predictions, but uncomfortable recommending use of them until they’re properly tested and validated. an exception: (Stein & Others) If you don’t like this, produce a competing alternative. (RELM)

14. an example: (Stein & Others) Another problem in getting multiple models into the analysis … Geophysicists generally don’t have the time to learn and conduct end-to-end SHA calculations (e.g., they’d need to combine their rupture forecast with some Intensity-Measure Relationship), & … SHA practitioners generally don’t have time to learn and implement physics based models.

15. So, to improve SHA we need to: • allow/encourage scientists to create their own physics-based models without making additional demands on their time, and • enable practitioners to easily use these models without having to understand or implement every detail of the model.

16. OpenSHA • So, to improve SHA we need to: • allow/encourage scientists to create their own physics-based models without making additional demands on their time, and • enable practitioners to easily use these models without having to understand or implement every detail of the model. RELM SCEC ITR Collaboration

17. Status of Seismic Hazard Analysis (SHA) needs more physics. we’ll have multiple options. “proper” SHA requires all options. SHA therefore needs a computational infrastructure capable of handling a potentially great number of arbitrarily complex models (a “Community Modeling Environment”).

18. Time Span Earthquake- Rupture Forecast List of Adjustable Parameters Intensity-Measure Relationship List of Supported Intensity-Measure Types List of Site-Related Independent Parameters Site Location List of Site- Related Parameters Intensity Measure Type & Level (IMT & IML) Hazard Calculation Any IMR or ERF can be plugged in Prob(IMT≥IML) OpenSHA: A framework where any arbitrarily complex (e.g., physics based) SHA component can “plug in” for end-to-end SHA calculations. • object oriented • free, open source • platform ind. • web/GUI enabled • Java (or wrapped code) • Evaluated & Validated

19. Time Span OpenSHA Rupturen,i Magnitude Probability Ave. Rake Rup. Surface Hypocenter Param. List Earthquake- Rupture Forecast Source1 Source2 Sourcei SourceI Site Location List of Site- Related Parameters Intensity Measure Type & Level (IMT & IML) … … Sourcei Rupture1,i Rupture2,i Rupturen,i RuptureN,i Intensity-Measure Relationship List of Supported Intensity-Measure Types List of Site-Related Independent Parameters … … Rupture probability Conditional probability of exceedance

20. Various IMR types (subclasses) Attenuation Relationships Gaussian dist. is assumed; mean and std. from various parameters IMT, IML(s) Multi-Site IMRs compute joint prob. of exceeding IML(s) at multiple sites (e.g., Wesson & Perkins, 2002) Rupture Site(s) Intensity-Measure Relationship List of Supported IMTs List of Site-Related Ind. Params Vector IMRs compute joint prob. of exceeding multiple IMTs (Bazzurro & Cornell, 2002) Simulation IMRs exceed. prob. computed using a suite of synthetic seismograms

21. OpenSHA: SHA Models Implemented: Intensity-Measure Relationships (Attenuation Relationships) Boore et al. (1997) Abrahamson & Silva (1997) Campbell (1997) Sadigh et al. (1997) Field (2000) Abrahamson (2000) Campbell & Bazorgnia (2003) ShakeMap (2003) Earthquake Rupture Forecasts PEER Area PEER Non-Planar Fault PEER Multi-Source PEER Logic Tree Poisson Fault ERF USGS/CGS (1996) STEP So. Cal. (real time) (2003) STEP Alaska Pipeline (2003) WGCEP (2002)

22. 1) Hazard Curve Calculator 2) Scenario ShakeMap Calculator decoupled because (3) typically takes hours or days 4) Hazard Map Plotter OpenSHA: Applications Available: 3) Hazard Map Data Calculator

23. Issue 1: • Who is going to host the multiple (perhaps physics-based) models as well as the databases they depend upon, especially since revisions/updates are inevitable? • Answer: • Developers will host their own models and data resources on their own computers as “Web Services” (enabling run-time access over the internet). (the SCEC ITR Collaboration is helping here)

24. Demos

25. How Has the ITR Collaboration Helped? • Issue 1: • Who is going to host the multiple, perhaps physics-based models, as well as the databases they depend upon (especially since revisions/updates are inevitable)? • Answer: • Developers will host their own models and data resources on their own computers as “Web Services” (enabling run-time access over the internet).

26. How Has the ITR Collaboration Helped? Presently Implemented Web Services: • SCEC Community Velocity Model (for setting site types) • GMT Mapping Service (for making hazard maps) • Earthquake Rupture Forecasts: • USGS/CGS 1996 Forecast • STEP So. Cal. Forecast • WGCEP-2002 Forecast (as wrapped Fortran Code)

27. How Has the ITR Collaboration Helped? Web Services make our applications lightweight & platform independent (e.g., users don’t have to install GMT) Web Services put the maintenance onus directly on the host

28. How Has the ITR Collaboration Helped? • Issue 2: • Hazard map calculations typically take several hours for just one set of models, but “proper” SHA requires that we explore all possible model combinations (or all parameter settings within a model). • Answer: • GRID computing (1st test: 7.5 hrs --> 30 minutes).

29. The End