This document discusses the development of a uniform, testable, global seismic hazard model. It proposes using a hybrid approach combining smoothed seismicity and tectonic strain rate data. This would provide spatially consistent seismic hazard values at a high resolution of 0.1° x 0.1°. The model would integrate global datasets on earthquake activity rates, fault sources, magnitude scaling, depth distributions, and ground motion prediction equations. The goal is to produce a fully transparent and reproducible global seismic hazard map and model that can then be refined at regional scales using more detailed local data and information.

1. The Potential for a Uniform, Testable,
Global Seismic Hazard Model
Graeme. Weatherill1, M. Pagani1, P. Bird2, C. Kreemer3, D. Monelli4,
D. Jackson2, Y. Kagan2, R. Stein5, Powell Working Group
1Global Earthquake Model Facility, Pavia
2UCLA, Los Angeles, CA
3U. Nevada, Reno, NV
4Global Earthquake Model Facility, ETH, Zurich
5United States Geological Survey, Menlo Park, CA

2. A Globally
“Uniform”
Seismic Hazard
Model
(GEM) Global
Component Datasets
Testing &
Evaluation
Spatially
homogenous
Scientific
Innovation
High Resolution
(0.1˚ ×0.1˚)
Transparent &
Replicable

3. Global Earthquake Activity Rate (GEAR) Model
‣ A hybrid strain/smoothed seismicity approach
Smoothed
Seismicity
Global Strain
Earthquake
Recurrence Model
Smoothing Process
Depth/
Mechanism
Earthquake
Recurrence Model
• Branches are not completely independent!
• Strain may help provide long term stationarity
Depth/
Mechanism Testing &
Evaluation

4. Global Smoothed Seismicity Model
Global Seismicity Forecast (end‐2012) (Kagan & Jackson, 2010)

5. From Strain Rate to Seismicity Rate – A Global “SHIFT”
‣ Seismic Hazard inferred from Tectonics “SHIFT” (Bird & Liu, 2007;
Bird et al. 2010)
‣ Seismic Moment Rate (M) from Strain Rate:
Incompressible:
At the ground surface:
Ordered:
<cz> = Coupled Depth (km)
μ = Shear Modulus (GPa)
Coupled Seismogenic Volume
A

6. From Strain Rate to Seismicity Rate – A Global “SHIFT”
‣ Model parameters specific to tectonic region class (Bird & Kagan, 2004):
‒ Coupled seismogenic thickness (<cz>)
‒ exponent (β) & corner magnitude (mc)
Intraplate (IPL)
Continental Rift Boundary
(CRB)
Continental Transform Fault
(CTF)
Continental Convergent
Boundary (CCB)
Ocean Spreading Ridge (OSR)
Ocean Transform Fault (OTF)
Oceanic Convergent
Boundary (OCB)
Subduction

7. Seismicity Rate from Strain Rate (SHIFT)

8. Hybrid (Strain + Smoothed Seismicity) Model
Weighted with Smoothed Seismicity (0.625) and Strain (0.375)

9. From GEAR to Global Hazard …
Seismic Hazard
Input Model
Global Activity
Rate Model
Source
Geometry
Magnitude
Scaling Relation
Depth
Distribution
Focal
Mechanism
Upper Bound
Magnitude
Ground Motion
Prediction Equations
(GMPE)
GMPE Logic Tree

10. Probability‐Based Upper Bound on Magnitude
Upper Bound Magnitude at Annual Probability of Exceedence ≥ 10‐6

11. Ground Motion Prediction Equations (GMPEs)
Active Shallow Crust
Subduction
Stable Continental
Akkar & Bommer (2010)
Chiou & Youngs (2008)
Zhao et al. (2006)
Abrahamson et al. (2013)
Atkinson & Boore (2003)
Zhao et al. (2006)
Atkinson & Boore (2006)
Silva et al (2002)
Pezeshk et al. (2011)
Global Recommendations from GEM
GMPE Global Component

12. Ground Motion Prediction Equations (GMPEs)
Active Shallow Crust
Subduction
Stable Continental
Akkar & Bommer (2010)
Chiou & Youngs (2008)
Zhao et al. (2006)
Abrahamson et al. (2013)
Atkinson & Boore (2003)
Zhao et al. (2006)
Atkinson & Boore (2006)
Silva et al (2002)
Pezeshk et al. (2011)
Global Recommendations from GEM
GMPE Global Component

13. Ground Motion Prediction Equations (GMPEs)
Active Shallow Crust
Subduction
Stable Continental
Akkar & Bommer (2010)
Chiou & Youngs (2008)
Zhao et al. (2006)
Abrahamson et al. (2013)
Atkinson & Boore (2003)
Zhao et al. (2006)
Atkinson & Boore (2006)
Silva et al (2002)
Pezeshk et al. (2011)
Global Recommendations from GEM
GMPE Global Component

14. A Globally Uniform Seismic Hazard Map …
Peak Ground Acceleration (PGA) with a 10 %
Probability of Being Exceeded in 50 years

15. … and model!
Peak Ground Acceleration (PGA) with a 2 %
Probability of Being Exceeded in 50 years

16. … and model!
1‐second Spectral Acceleration with a 10 %
Probability of Being Exceeded in 50 years

17. Where to develop? – Earthquake Catalogues
‣ Assimilate highest quality historical and instrumental catalogues
‣ Account for completeness
ISC Reviewed
Bulletin (M > 3)

18. Where to develop? – Subduction Sources
Faulted Earth/USGS Subduction Sources (Wallace et al., 2012)

19. Where to develop? ‐ Intraplate Regions
‣ Strain cannot resolve; catalogues too short!
‣ Active research from the Powell Working Group
Stable Continental Region Polygons (EPRI, 1994)
Earthquakes from Schulte & Mooney (2005)

20. Moving From Global to Regional
‣ Experimental & Provisional
‣ Missing information available at regional scales:
‒ Detailed information on fault geology and activity
‒ Time‐dependence
‒ Catalogues with lower completeness magnitudes
‣ To compare global and local, consistency is desirable:
‒ Calculation Implementation
‒ Testing & Evaluation