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Ned Field

I specialize in the development of earthquake-forecast models, which are one of the two main modeling components used in modern seismic-hazard analysis (the other being a ground-motion model).

My focus area has mainly been California, which due to an abundance of riches in terms of both scientific talent and data constraints, has enabled the forging of state-or-the-art methodologies (California also hosts trillions of dollars in assets and, consequently, two-thirds of the nationwide seismic risk).  The multi-disciplinary nature of earthquake forecasting necessitates a collaborative approach, which we have achieved through the Working Group on California Earthquake Probabilities (  I led the development of our most recent model, the Third Uniform California Earthquake Rupture Forecast (UCERF3;, which is innovative in terms of representing both multi-fault ruptures and spatiotemporal clustering (e.g. aftershocks); the relevance of both these effects was dramatically exemplified in a recent sequence of damaging earthquakes in New Zealand.  Our forecast models influence a variety of risk mitigation activities, including construction requirements (building codes) and insurance rates.  Important themes going forward include: a better quantification of uncertainties; the use of more physics-based approaches; and the need to add “valuation” to our verification and validation protocols (“all models are wrong” at some level, so a relevant question is whether a new and improved one really represents value added with respect to risk assessment).

I have also led the development of OpenSHA (, which is an object-oriented, GUI-enabled, open-source, and platform-independent computational framework for conducting seismic hazard analysis.  OpenSHA also makes use of distributed object technologies (components can exist anywhere over the Internet), it runs on high-performance super computers, and it supports loss modeling as well.

I am also a member of the planning committee of the Southern California Earthquake Center (, and as such, I help formulated the SCEC science plan, write the annual RFPs, and review and recommend funding levels for proposals submitted to SCEC.


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