CSEP2 Community Responses

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Questionnaire

• What are the scientific questions to be answered by experiments involving your model?

• Model software requirements? Will the model be computed internal/external to CSEP? Required computing/memory/storage? Automated/On-demand? Versioned code? Status of code?

• Object of forecast? Epicenters, Hypocenters, Faults? Cast as rates/probabilities, Sets of simulated catalogs? Forecast horizons, updates?

• Required data inputs to compute forecast?

• Authoritative data source for testing forecasts?

• Available/unavailable tests, metrics etc. If unavailable, what scientific/computational developments need to occur to implement these tests?

• Specific ideas for Retrospective/Prospective testing? Timescales?

• Community involvement? competing models? New models/extant CSEP models?

Responses

These responses will act as living documents that we can refine as time progresses.

UCERF3-ETAS

What are the scientific questions to be answered by experiments involving your model?

Ideally, whether elastic rebound is really needed when adding spatiotemporal clustering to fault-based models, whether ETAS is an adequate statistical proxy for large-event clustering, and whether large triggered events can nucleate well within the rupture area of the triggering event (or only around the edges of the latter).

The practical question is whether including faults is value added.

Model software requirements? Will the model be computed internal/external to CSEP? Required computing/memory/storage? Automated/On-demand? Versioned code? Status of code?

U3ETAS presently requires high performance computing. Each simulation (synthetic catalog) takes from 1 to 20 minutes to generate, and we need some number of these to make robust statistical inferences (with the actual number depending on the metric of interest) . Results published to date have utilized about 10,000 simulations. Kevin is configuring things so that anyone can run a set of simulations (so this could be done either internal or external to CSEP)(. Nothing will be automated anytime soon.

Object of forecast? Epicenters, Hypocenters, Faults? Cast as rates/probabilities, Sets of simulated catalogs? Forecast horizons, updates?

Results are some number of simulated catalogs, with finite fault surfaces for larger events. The start time and duration are flexible.

Required data inputs to compute forecast?

All potentially influential M≥2.5 events before the start time, including finite surfaces for larger Qks (getting the latter in real time is still to be dealt with).

Authoritative data source for testing forecasts?

With respect to the M≥2.5 events and finite rupture surfaces, COMCAT? Real-time catalog completeness may still be an issue.

Available/unavailable tests, metrics etc. If unavailable, what scientific/computational developments need to occur to implement these tests?

We can generate pretty much anything that can be computed for real earthquakes, including the Page and van der Elst Turing tests (Turing‐style tests for UCERF3 synthetic catalogs BSSA 108 (2), 729-741).

Specific ideas for Retrospective/Prospective testing? Timescales?

Perhaps we should start with time periods following large historic events in CA (e.g., Northridge, Landers, etc.). We might want to test quiet periods as well? The bid task is being able to deal with simulation-based forecasts.

Community involvement? competing models? New models/extant CSEP models?

Keep in mind that we also have a no-faults version of U3ETAS, and there are all kinds of improvements that could be made to these models (e.g., aleatory variability in productivity parameters).

Here is our present to-do list with respect to U3ETAS:

1) train others to run models on HPC and generate plots

2) fetch recent M≥2.5 seismicity data from comcat and stitch together with the U3 catalog (which ends around 2014).

3) associate any large CA events to U3 fault sections (probabilistically because there will never be a perfect fit).

4) deal with catalog incompleteness?

In terms of testing usefulness, here is what I’d like to do at some point:

We know that the rate of little events varies significantly with time, and that the probability of big events correlates with the rate of little events. But there are uncertainties in what will happen looking forward, so the question is whether our forecasts provide useful information given these uncertainties. Take any metric we are interested in (e.g., rate of M≥2.5 events or statewide financial losses); how do actual fluctuations compare with, say, the 95% confidence bounds from forecasts.. Starting from whenever the M≥2.5 catalog is complete, I’d like to make forecasts at increments in time moving forward (monthly or yearly, or at some trigger points such as large event or before particularly quiet periods), and the plot the 95% confidence bounds (or whatever) of the forecast against what actually happens. We can also project this analysis into the future by randomly choosing one the forecasts as what “actually” happens. Again, the point is to tests whether our forecasts have value given the aleatory uncertainties looking forward. Of course the answer will depend on the hazard or risk metric one care's about (so we will need to choose some to test), and the answer will also presumably vary depending on what’s happened recently (e.g., our forecast will presumably have some value after large events such as HayWired, but what about following particularly quiet times? Could CEA lower reinsurance levels during the latter?) This analysis will require significant HPC resources.

USGS Aftershock Forecasts (R&J and ETAS)

Submitted by: Jeanne Hardebeck

Response for the planned USGS routine aftershock forecasting. We will be rolling out Reasenberg & Jones forecasts in late August 2018, with ETAS forecasts to follow. Forecasts will be for aftershocks following M>=5 earthquakes, and smaller events of interest, within the US.

What are the scientific questions to be answered by experiments involving your model?

These forecasts are meant to inform the public and decision-makers, not to address any scientific questions. As we evolve from Reasenberg & Jones to ETAS, we will be able to tests these two models against each other.

Model software requirements

Will the model be computed internal/external to CSEP? Required computing/memory/storage? Automated/On-demand? Versioned code? Status of code?

Forecasts will be computed externally to CSEP. Currently on-demand, but in the process of automating.

Object of forecast

Epicenters, Hypocenters, Faults? Cast as rates/probabilities, Sets of simulated catalogs? Forecast horizons, updates?

Forecast is cast as a PDF of the number of event hypocenters within a spatial

region, time period, and magnitude range. There is no expectation that this

PDF is any particular kind of distribution.

The ETAS forecasts will include something similar to a set of simulated catalogs, but not exactly. The forecasts are based on temporal simulated event sets, while a static spatial kernel is used to spatially distribute the event rate. So there are temporal simulated catalogs. Spatial-temporal simulated catalogs could be created using the spatial kernel, but wouldn't have the full level of spatial correlations of a true ETAS simulation.

Forecast horizons will range from 1 day to 1 year, and updating will occur frequently. Therefore, many forecasts will overlap, making them non-independent.

Required data inputs to compute forecast?

Forecasts will be computed externally to CSEP.

Authoritative data source for testing forecasts?

ComCat.

Available/unavailable tests, metrics etc. If unavailable, what scientific/computational developments need to occur to implement these tests?

 ??

Specific ideas for Retrospective/Prospective testing? Timescales?

 ??

Community involvement? competing models? New models/extant CSEP models?

 ??

New Zealand Forecasts (STEPJAVA)

Submitted by: Matt Gerstenberger

What are the scientific questions to be answered by experiments involving your model?

Should we continue exploring this model?

Does the model provide additional information over any other model?

How much is the variability in performance across magnitude, space and time?

How does the model perform in low seis vs high seis regions?

Model software requirements? Will the model be computed internal/external to CSEP? Required computing/memory/storage? Automated/On-demand? Versioned code? Status of code?

internal; no idea; either; no; operating in two csep testing centres, with similar in a third

Object of forecast? Epicenters, Hypocenters, Faults? Cast as rates/probabilities, Sets of simulated catalogs? Forecast horizons, updates?

hypocenters or epicenters; rates/probs; any forecast horizon or update

Required data inputs to compute forecast?

standard eq catalogue: time, lat/lon/depth, mag

Authoritative data source for testing forecasts?

standard csep

Available/unavailable tests, metrics etc. If unavailable, what scientific/computational developments need to occur to implement these tests?

standard csep

Specific ideas for Retrospective/Prospective testing? Timescales?

understanding spatial variability across models - both within "sequence" and across regions. weeks to multiple years/decades

exploring retrospective testing to understand variability in performace

Community involvement? competing models? New models/extant CSEP models?

all other short, medium and long-term models.

General Responses

Submitted by: Warner Marzocchi

What are the scientific questions to be answered by experiments involving your model?

I think that the most important issue has to remain the forecast. This is mostly what society asks us. Of course, we may also implement tests for specific scientific hypothesis but we have to be aware than society needs forecasts and hazard.

Model software requirements? Will the model be computed internal/external to CSEP? Required computing/memory/storage? Automated/On-demand? Versioned code? Status of code?

I think it would be good if any model will provide simulated catalogs from which we may calculate any statistics we want. This allows us to overcome many shortcomings of the current tests, such as the independence, the Poisson assumption and including epistemic uncertainty.

I would be flexible about where the model is stored. I prefer inside CSEP but I would allow external models to be part of the game if this allows us to increment the number of CSEP people.

Object of forecast? Epicenters, Hypocenters, Faults? Cast as rates/probabilities, Sets of simulated catalogs? Forecast horizons, updates?

Simulated catalogs

Required data inputs to compute forecast?

Seismic catalog

Authoritative data source for testing forecasts?

The same as in CSEP1

Available/unavailable tests, metrics etc. If unavailable, what scientific/computational developments need to occur to implement these tests?

I would implement more scoring systems as the weather forecasting community is doing.

Specific ideas for Retrospective/Prospective testing? Timescales?

The short-term is important

Community involvement? competing models? New models/extant CSEP models?

I would definitely include some procedures to create ensemble models using the scores.