Unified Structural Representation

1. Community velocity model (CVM): Improve and evaluate the CVM by extending the parameterization to include anelastic dissipation and topography, testing the model and derived parameters (e.g., velocity, density) with available data (e.g., waveforms, gravity), and extending the model to the offshore regions; develop new data assimilation techniques for refining the CVM.
2. Community fault model (CFM): Define the geometry, slip, and slip rate of seismogenic faults in Southern California, with emphasis on large faults poorly represented in current hazard models; coordinate the compilation of fault databases; produce a coarse-resolution fault model for Southern California (CFM-A); develop high-resolution fault models for selected areas (CFM-B); provide dynamic linkages between fault databases and fault models; evaluate alternative source characterizations.
3. Unified structural representation (USR): Develop specifications for a unified, object-oriented representation of active faults and 3D earth structure for use in fault-system analysis and ground-motion prediction; begin integration of CVM and CFM into the USR; identify and prioritize data-gathering efforts to improve the USR.

Fault Systems

1. Fault-system behavior: Quantify the space-time behavior of Southern California seismicity using paleoseismology, tectonic geomorphology, historical records, and instrumental catalogs; compare short-term geodetic rates with long-term geologic rates and explain the differences; investigate the effects of afterslip, viscoelasticity, and poroelasticity on long-term stress transfer between faults following moderate to large earthquakes.
2. Deformation models: Develop and validate 3D quasi-static codes for simulating block motions and deformations in coordination with GEM, GeoFEM, ACES, and other modeling efforts; develop deformation models of Southern California consistent with observed topography, fault geometries and rheological properties, geologic slip rates, geodetic motions, and earthquake histories; use these models to infer fault slip, rheologic stratification, and fault interactions through stress transfer.
3. Earthquake simulators: Develop and validate codes for simulating earthquake catalogs in coordination with GEM, GeoFEM, ACES, and other modeling efforts; assess the utility of these models in forecasting Southern California earthquakes and in testing empirical forecasting schemes as part of the RELM effort.
4. Offshore fault systems: Plan strategies for interdisciplinary investigations of the fault systems offshore Southern California in coordination with the USGS marine program, the NSF MARGINS program, and other oceanographic activities.

Earthquake Source Physics

1. Reference earthquakes: Establish a set of reference events with documentation that includes databases of seismic, geodetic, and geologic observations as well as models of fault geometries, near-source structures, deformation histories, and stress changes.
2. Fault-zone structure: Investigate the 3D structure of fault zones, including step-overs, transfer zones, branching points, and how this structure is coupled to stress heterogeneity and earthquake complexity; apply high-resolution location techniques to resolve the fine structure of microseismicity on active faults in Southern California, and compare with similar studies of other faults.
3. Source models: Begin to develop and validate numerical algorithms for simulating 3D earthquake sources, including dynamical models of fault rupture consistent with laboratory-based friction laws and stochastic models of high-frequency radiation from faults; test source models against data from reference earthquakes.
4. Rupture dynamics: Begin to develop techniques for the assimilation of laboratory-based friction, seismic, and geodetic data into dynamic rupture models; assess the discrepancies between laboratory-based friction laws that explain some observed fault-system behaviors (e.g., earthquake productivity, post-seismic response) and seismological inferences from large earthquakes (e.g., fracture energies, particle velocities, and accelerations).
5. Earthquake interactions: Develop more realistic models for short-term stress transfer, including rate- and state-dependent friction, dynamic triggering, and fault-zone damage/healing mechanisms; test stress-transfer models and earthquake probability estimates derived from them.

Ground Motions

1. Deterministic wavefield models: Develop anelastic wave-propagation codes and nonlinear site-response codes; validate these codes by intercomparisons of computed wavefields, including those for reference earthquakes.
2. CVM improvement: Use data from reference events to assess, as a function of frequency, wavefield simulations based on the CVM; compare with results from other structural representations (including 1D and 2D representations); plan strategy for improving the accuracy and frequency range of deterministic wavefield modeling, including the assimilation of seismographic data into the CVM.
3. Stochastic wavefield models: Develop stochastic models of high-frequency radiation that can be combined with deterministic models of low-frequency radiation to predict strong ground motions; validate the models by intercomparisons and testing with observed data.
4. Earthquake scenarios: Simulate ground motions for probable earthquake scenarios by combining source, wave-propagation, and site-response models.

Seismic Hazard Analysis

1. OpenSHA: Contribute to the developing Community Modeling Environment for Seismic Hazard Analysis (known as OpenSHA; www.OpenSHA.org). This is an open-source, object oriented, and web-enabled framework that will allow various, arbitrarily complex (e.g., physics based) earthquake-rupture forecasts, ground-motion models, and engineering response measures to plug in for SHA. Part of this effort is to use information technology to enable the various models and databases they depend upon to be geographically distributed and run-time accessible. Contributions may include: 1) implementing any of the various components (in Java or other language), 2) testing any of the various components/applications, and 3) extending the existing framework to enable other capabilities, such as vector-valued hazard analysis, to interface with existing risk/loss estimation tools, or to web-enable the testing of the various RELM forecast models.
2. Regional Earthquake Likelihood Models (RELM): Via the RELM working group (www.RELM.org), help develop various, viable earthquake-forecast models for southern California (the more physics-based approaches should be developed in coordination with the Fault Systems focus group). Continue the development of shared data resources needed by the RELM working group, especially in terms of making them on-line and machine readable. These should be coordinated with other focus/disciplinary groups as appropriate (e.g., the needed quantification of alternative, internally-consistent fault-system representations should be coordinated with the CFM effort). Establish quantitative tests of the various forecast models using observed seismicity, precarious-rock constraints, historically observed intensity levels, or other viable approaches.
3. Improved Intensity-Measure Relationships: Work with the Ground Motion focus group and/or the Implementation Interface to develop improved models for predicting intensity measures (empirical attenuation relationships, theoretical models, or hybrid approaches). Proposals to implement new types of Intensity Measures (new functionals of ground motion, or vectors of functionals) that predict engineering damage measures better than traditional peak acceleration or spectral response are encouraged.

Seismology

1. Data gathering: Improve the distribution and accuracy of regional seismic data, including strong-motion data, in coordination with the California Integrated Seismic Network (CISN), the Advanced National Seismic System (ANSS), COSMOS, the IRIS Data Management Center (IRIS DMC), and other organizations; plan SCEC2 seismic experiments in coordination with EarthScope and other programs.
2. Data products: Improve earthquake catalogs (locations, sizes, and source mechanisms), structural models, and capabilities for visualizing earthquake information; improve methods for assimilating broadband seismic data into 3D structural models.
3. Post-earthquake response: Foster capabilities for post-earthquake deployments of portable broadband instruments in coordination with IRIS, EERI, and other organizations.

Geodesy

1. Data gathering: Operate the Southern California Integrated GPS Network (SCIGN) in partnership with JPL/NASA; improve the distribution and accuracy of data from SCIGN, survey-mode GPS deployments, and InSAR systems in coordination with UNAVCO, EarthScope, and the California Spatial Reference Center; plan SCEC2 survey-mode GPS experiments in coordination with these organizations; collect other data relevant to time-dependent deformation.
2. Data products: Release version 3.0 of the Crustal Motion Model (CMM); produce surface-strain maps and fault-slip models from the CMM; produce time-dependent deformation fields for use in stress-transfer investigations; incorporate InSAR imaging of tectonic deformations into the CMM.
3. Post-earthquake response: Foster capabilities for InSAR imaging of co- and post-seismic deformations and for post-earthquake deployments of portable GPS instruments in coordination with UNAVCO, NASA, and other organizations.

Geology

1. Data gathering: Plan, coordinate, and provide infrastructure for geologic fieldwork; formulate field tests of paleoseismic methodology; develop databases comprising high-resolution topography, slip rates of active faults, paleoseismic chronologies, slip in past earthquakes, paleo-indicators of strong ground motions, and other geologic measurements of active tectonics; foster subsurface analysis of fault systems, including blind thrusts.
2. Data products: Integrate field and laboratory efforts to date geologic samples and events, including standardized procedures for field documentation, sample treatment, dating methodologies, and data archiving and distribution; produce long-term rupture histories for selected fault systems in Southern California.
3. Post-earthquake response: Foster capabilities for post-earthquake field studies in coordination with EERI and other organizations.

Fault and Rock Mechanics

1. Data gathering: Improve the distribution and accuracy of regional seismic data, including strong-motion data, in coordination with the California Integrated Seismic Network (CISN), the Advanced National Seismic System (ANSS), COSMOS, the IRIS Data Management Center (IRIS DMC), and other organizations; plan SCEC2 seismic experiments in coordination with EarthScope and other programs.
2. Data products: Improve earthquake catalogs (locations, sizes, and source mechanisms), structural models, and capabilities for visualizing earthquake information; improve methods for assimilating broadband seismic data into 3D structural models.
3. Post-earthquake response: Foster capabilities for post-earthquake deployments of portable broadband instruments in coordination with IRIS, EERI, and other organizations.