CSEP Workshop 09-08-2018

Workshop goals

• CSEP needs overhaul
• Develop concrete plans to start science/software development on CSEP2
• Driving from new science needs and new models
• Plans for coordinating developer resources

Workshop Outcomes

• Science priorities and how software supports this
• New experiments:
  • Testing USGS OEF models
  • Forecasts of finite-ruptures
  • Want to develop documents for select new experiments for CSEP2 experiments to drive CSEP2 software developments
• Prototype new experiments!

General Thoughts [Vidale]

• Progress on Basic Science
• Concrete demonstration of progress

USGS Perspectives on CSEP2.0

• Rigorous testing is an essential aspect of developing and deploying all manner of earthquake forecast products
• High priorities:
  • UCERF3
  • USGS National Seismic Hazard model
  • Operational Aftershock Earthquake Forecasting
  • Improved after shock forecasting
• CSEP impacts on USGS Hazard assessments
  • Helmstetter’s adaptive smoothing in UCERF3
  • S-test for smoothing parameters
• USGS Aftershock forecasting
  • Expanding models to expand epistemic uncertainty
  • Developing pathway for new methods
  • Improving reliability and skill
  • New Models must be approved by NEPEC
• Different models give different outputs
  • Users want spatial forecasts and hazard
• ETAS vs. R&J
  • ETAS helps to capture variability of the real world. Advantage over R&J
• Testing to hone models
  • R&J home parameters and choices (sequence specific, Bayesian)
  • Fast ETAS -- applying smoothing to spatial component
• Testing for societal acceptance (how can we get society to accept the results)
• Testing simulated catalog forecasts
  • Projects of event sets to form various PDFs, interevent time
  • Could be mapped to ground-motion space
• Retrospective testing is very important
• Internal or External or Independent
• USGS Models:
  • NSHM
  • 1-year induced seismicity forecasts
  • RJ Operational Earthquake Forecasts
  • FAST-Etas
  • UCERF3

CSEP2 development strategy needs to be coordinated between international community

• • Modularize toolbox
  • Unit tests for all CSEP primitives
  • Acceptance tests for all CSEP
  • Documentation is thorough

R&J Forecasts at USGS

• Linked to website at the USGS in beta, currently planned to launch in October
• Workflow:

1. Compute R&J using GUI tool 2. Forecast sent from GUI to NEIC 3. NEIC uses forecast to populate pre-written web template 4. Time to solution goal is ~2 hours

• Working towards automating this process and including more models
• Why R&J?
  • Decades of use in California
  • Approved by NEPEC
• Testing Goals
  • Transparency: demonstrate that we are providing to the public is being evaluated
  • Baseline: they can be compared to R&J to measure improvement
  • Testing the tests
• Testing challenges:
  • Sequence based, rather than grid-based
  • EQ probability not necessarily poissonian
  • Updating in real-time, overlapping windows
  • Spatial forecasts not aligned on grid, and not aligned in time
  • Modeling epistemic and aleatory
  • Requires looking at simulation based tests
  • Overlapping, non-independent forecasts
  • External forecasts
    • Test what the public is actually seeing
  • Run within CSEP
    • Difficult to duplicate
  • Value in publicly testing forecasts within CSEP
• Testing requirements:
  • Non-grid-based forecasts
  • Simulations
  • External forecasts

Experiments for FastETAS

• FastETAS will be implemented in USGS system
• GUI based system that takes ComCat data and produces quick summaries
• Close to ‘vanilla’ ETAS as possible
• Tweak to regular ETAS
  • Masking applied to prevent super-critical range
  • Independent mainshock productivity
  • Mc-dependent productivity for Generic model
  • Time dependent Mc
  • Spatial forecast: physics-motivated dressed kernel
• Can transition from spatial-rate to time-dependent spatial hazard
• Evaluating forecasts
  • Information gain? Not that useful.
  • Things to test:
    • Misfit, over/under-predictions, surprise rate
    • Reliability horizon
    • Spatial performance
    • Shaking forecast
    • Shaking forecast
    • Generic vs. bayesian
    • Value of additional parameters
    • Other tweaks

Testing UCERF3

• Requirements:
  • Non-GR MFS
  • Bulge of ~Mw 6.7 earthquakes
  • Fault participation
  • MFD near faults has 1st order impact on conditional triggering probabilities
  • Elastic rebound needed
  • U3ETAS is simulation based
• Questions
  • Are near-fault MFDs non-GR?
  • Are conditional triggering probabilities really larger near faults?
  • Is elastic-rebound needed?
  • Dealing with epistemic uncertainties?
  • Bulge in regional MFDs?
  • Testing simulation-based forecasts?
  • Is U3ETAS really more useful?
• Looking forward
  • Implement CSEP1 style tests for simulation-based forecasts
  • Apply retrospectively to U3ETAS, U3NoFaultETAS, Fast-ETAS
  • Apply above tests prospectively
  • Implement “turning-style” tests
  • Test fault or cell participation
  • Epistemic Uncertainty
  • Test relative model usefulness

Testing Stochastic Event Sets

• Advantages: greater flexibility including tests incorporating space-time correlations.
• Challenges: May still need gridding of the synthetic catalogs for some applications.
• Consistency tests of simulation-based models
  • A wide range of consistency tests is possible
  • Example: Clustering
    • Compare a statistic computed from the real catalog with distribution of same statistic from catalog
    • Each time-period results in a p-value; combined distribution can be compared to uniform distribution
  • Example: For a distribution
    • Use K-S statistics to compare the synthetic distribution from catalog distribution
• Simulation statistics to do similar job to existing CSEP1 consistency tests
  • Mimic N-test, M-test, S-test
  • Inter-event time distribution
  • Inter-event distance distribution
  • Total earthquake rate distribution
  • Information gain important
• Synthetic catalog updating issues
  • Length of simulated catalogs
  • Simulate for the longest period
  • Update intervals
• Key decisions
  • Data management the most important part of system
  • Updating periods and magnitudes
  • How much effort should CSEP put into testing models of small-earthquake occurrence?
  • Scientific vs operational forecasting requirements

Future of the NZ Testing Center

• Uncertain future
• Difficulty maintain the last 10 years; both workloads and lack of appropriate skills
• Significant GeoNet catalogue data problems
• How do we best align with other international CSEP work? Don’t want to split efforts within CSEP
• CSEP Culture
  • Perception of relevance to those outside of CSEP need to expand CSEP community
• Need more tests targeting the end-users of the models
• Better communication of the results. How can we include others?
• Take forecasts into hazard and loss space.
• Hybridisation module
  • Module to create hybrid forecasts from current CSEP models
• Aim to broaden involvement of science community in CSEP activities.

Perspectives from CSEP Japan

• Testing different model classes
• Looking at finite-fault ETAS model
• Hypocentral ETAS model (3D volume)
• Combine 3D+finite-fault model
• ETAS+Focal mechanism

Perspectives from China

• CSEP Software was installed in the institute of geophysics
• Definitions for CSEP Experiments
• Software did not work, so needed to create their own homebrew version of the software.
• CN-CSEP needs international collaboration
• New Forecasting region for CSEP2.0

Perspectives from Italy

• Poisson assumption in space and time does not hold
• Models need to include epistemic uncertainty
• Discretization on a grid, might need to stay to engage with many different models.
• Should make changes that affect CSEP 1.0 the least
• Need to move toward synthetic catalogs
• Synthetic catalogs can be used to generate test distribution to replace the Poisson distribution