Ned Field
Ned (Edward) Field is a Research Geophysicist with the Earthquake Hazards Program.
Ned Field coordinates and leads the development of earthquake forecast models for the USGS Earthquake Hazards Program. These forecasts, coupled with ground-motion models, form the basis of modern seismic hazard and risk analyses. Their development is multidisciplinary and collaborative (a "systems science" problem) in that information from a broad range of disciplines (e.g., seismology, geodesy, geology, paleoseismology, and earthquake physics) must reconciled.
Recent accomplishments and ongoing challenges involve representation of multi-fault ruptures and spatiotemporal clustering (e.g., aftershocks), improved uncertainty estimates, applying more physics-based approaches, and the need to add "valuation" to our verification and validation protocols (i.e., a greater focus on usefulness). Ned is also involved in developing and deploying end-to-end seismic hazard and risk computational platforms. The resultant models influence a variety of risk mitigation activities, including construction requirements (building codes) and earthquake insurance rates.
Science and Products
Computing elastic‐rebound‐motivated rarthquake probabilities in unsegmented fault models: a new methodology supported by physics‐based simulators
“All Models Are Wrong, but Some Are Useful”
Documentation for the 2014 update of the United States national seismic hazard maps
Aftershock risks such as those demonstrated by the recent events in New Zealand and Japan
The UCERF3 grand inversion: Solving for the long‐term rate of ruptures in a fault system
2014 update of the U.S. national seismic hazard maps
Stress-based aftershock forecasts made within 24h post mainshock: Expected north San Francisco Bay area seismicity changes after the 2014 M=6.0 West Napa earthquake
Uniform California earthquake rupture forecast, version 3 (UCERF3): the time-independent model
A comparison among observations and earthquake simulator results for the allcal2 California fault model
Trimming the UCERF2 hazard logic tree
CyberShake: A Physics-Based Seismic Hazard Model for Southern California
Conditional, time-dependent probabilities for segmented Type-A faults in the WGCEP UCERF 2
New USGS map shows where damaging earthquakes are most likely to occur in US
USGS scientists and our partners recently revealed the latest National Seismic Hazard Model, showing that nearly 75% of the United States could experience a damaging earthquake, emphasizing seismic hazards span a significant part of the country.
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Filter Total Items: 58
Computing elastic‐rebound‐motivated rarthquake probabilities in unsegmented fault models: a new methodology supported by physics‐based simulators
A methodology is presented for computing elastic‐rebound‐based probabilities in an unsegmented fault or fault system, which involves computing along‐fault averages of renewal‐model parameters. The approach is less biased and more self‐consistent than a logical extension of that applied most recently for multisegment ruptures in California. It also enables the application of magnitude‐dependent apeAuthorsEdward H. Field“All Models Are Wrong, but Some Are Useful”
Building a new model, especially one used for policy purposes, takes considerable time, effort, and resources. In justifying such expenditures, one inevitably spends a lot of time denigrating previous models. For example, in pitching the third Uniform California Earthquake Rupture Forecast (UCERF3) (http://www.WGCEP.org/UCERF3), criticisms of the previous model included fault‐segmentation assumptiAuthorsEdward H. FieldDocumentation for the 2014 update of the United States national seismic hazard maps
The national seismic hazard maps for the conterminous United States have been updated to account for new methods, models, and data that have been obtained since the 2008 maps were released (Petersen and others, 2008). The input models are improved from those implemented in 2008 by using new ground motion models that have incorporated about twice as many earthquake strong ground shaking data and byAuthorsMark D. Petersen, Morgan P. Moschetti, Peter M. Powers, Charles S. Mueller, Kathleen M. Haller, Arthur D. Frankel, Yuehua Zeng, Sanaz Rezaeian, Stephen C. Harmsen, Oliver S. Boyd, Edward H. Field, Rui Chen, Kenneth S. Rukstales, Nico Luco, Russell L. Wheeler, Robert A. Williams, Anna H. OlsenAftershock risks such as those demonstrated by the recent events in New Zealand and Japan
Recent earthquakes in New Zealand and Japan show that it is important to consider the spatial and temporal distribution of aftershocks following large magnitude events since the probability of high intensity ground motions from aftershocks, which are capable of causing significant societal impact, can be considerable. This is due to the fact that a mainshock will have many aftershocks, some of whiAuthorsNilesh Shome, Nicolas Luco, Matt Gerstenberger, Oliver S. Boyd, Edward H. Field, Abbie Liel, John W. van de LindtThe UCERF3 grand inversion: Solving for the long‐term rate of ruptures in a fault system
We present implementation details, testing, and results from a new inversion‐based methodology, known colloquially as the “grand inversion,” developed for the Uniform California Earthquake Rupture Forecast (UCERF3). We employ a parallel simulated annealing algorithm to solve for the long‐term rate of all ruptures that extend through the seismogenic thickness on major mapped faults in California whAuthorsMorgan T. Page, Edward H. Field, Kevin Milner, Peter M. Powers2014 update of the U.S. national seismic hazard maps
We held 8 regional and topical workshops across the U.S. to gather information for these maps. The maps were available to the public for comment during a 60-day period. A Steering Committee (9 experts) was assembled to review the inputs and results and provide additional insights. The maps have been presented at several professional meetings. In this talk we discuss: (1) CEUS, (2) WUS (outsideAuthorsMark D. Petersen, Morgan P. Moschetti, Peter M. Powers, Charles S. Mueller, Kathleen M. Haller, Arthur D. Frankel, Yuehua Zeng, Sanaz Rezaeian, Stephen C. Harmsen, Oliver S. Boyd, Edward H. Field, R Chen, Kenneth S. Rukstales, Nicolas Luco, Russell L. Wheeler, Anna H. OlsenStress-based aftershock forecasts made within 24h post mainshock: Expected north San Francisco Bay area seismicity changes after the 2014 M=6.0 West Napa earthquake
We calculate stress changes resulting from the M = 6.0 West Napa earthquake on north San Francisco Bay area faults. The earthquake ruptured within a series of long faults that pose significant hazard to the Bay area, and we are thus concerned with potential increases in the probability of a large earthquake through stress transfer. We conduct this exercise as a prospective test because the skill oAuthorsThomas E. Parsons, Margaret Segou, Volkan Sevilgen, Kevin Milner, Edward H. Field, Shinji Toda, Ross S. SteinUniform California earthquake rupture forecast, version 3 (UCERF3): the time-independent model
In this report we present the time-independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time-averaged frequency of potentially damaging earthquakes in California. The primary achievements have been to relax fault segmentation assumptions and to include multifault ruptures, both limitaAuthorsEdward H. Field, Glenn P. Biasi, Peter Bird, Timothy E. Dawson, Karen R. Felzer, David D. Jackson, Kaj M. Johnson, Thomas H. Jordan, Christopher Madden, Andrew J. Michael, Kevin R. Milner, Morgan T. Page, Thomas Parsons, Peter M. Powers, Bruce E. Shaw, Wayne R. Thatcher, Ray J. Weldon, Yuehua ZengA comparison among observations and earthquake simulator results for the allcal2 California fault model
In order to understand earthquake hazards we would ideally have a statistical description of earthquakes for tens of thousands of years. Unfortunately the ∼100‐year instrumental, several 100‐year historical, and few 1000‐year paleoseismological records are woefully inadequate to provide a statistically significant record. Physics‐based earthquake simulators can generate arbitrarily long historiesAuthorsTerry. E. Tullis, Keith B. Richards-Dinger, Michael Barall, James H. Dieterich, Edward H. Field, Eric M. Heien, Louise Kellogg, Fred F. Pollitz, John B. Rundle, Michael K. Sachs, Donald L. Turcotte, Steven N. Ward, M. Burak YikilmazTrimming the UCERF2 hazard logic tree
The Uniform California Earthquake Rupture Forecast 2 (UCERF2) is a fully time‐dependent earthquake rupture forecast developed with sponsorship of the California Earthquake Authority (Working Group on California Earthquake Probabilities [WGCEP], 2007; Field et al., 2009). UCERF2 contains 480 logic‐tree branches reflecting choices among nine modeling uncertainties in the earthquake rate model shownAuthorsKeith A. Porter, Edward H. Field, Kevin MilnerCyberShake: A Physics-Based Seismic Hazard Model for Southern California
CyberShake, as part of the Southern California Earthquake Center’s (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin wiAuthorsR. Graves, T.H. Jordan, S. Callaghan, E. Deelman, Edward H. Field, G. Juve, C. Kesselman, P. Maechling, G. Mehta, K. Milner, D. Okaya, P. Small, K. VahiConditional, time-dependent probabilities for segmented Type-A faults in the WGCEP UCERF 2
This appendix presents elastic-rebound-theory (ERT) motivated time-dependent probabilities, conditioned on the date of last earthquake, for the segmented type-A fault models of the 2007 Working Group on California Earthquake Probabilities (WGCEP). These probabilities are included as one option in the WGCEP?s Uniform California Earthquake Rupture Forecast 2 (UCERF 2), with the other options being tAuthorsEdward H. Field, Vipin Gupta - Software
- News
New USGS map shows where damaging earthquakes are most likely to occur in US
USGS scientists and our partners recently revealed the latest National Seismic Hazard Model, showing that nearly 75% of the United States could experience a damaging earthquake, emphasizing seismic hazards span a significant part of the country.