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SCEC Community Models (CXM)

CXM WORKING GROUP
CXM Coordinating Committee
CFM: Scott Marshall
CGM: David Sandwell
CRM: Liz Hearn
CSM: Jeanne Hardebeck
CTM: Wayne Thatcher
CVM: Andreas Plesch
TECHNICAL SUPPORT
SCEC COMMUNITY MODELS
Community Fault Model
Community Geodetic Model
Community Rheology Model
Community Stress Model
Community Thermal Model
Community Velocity Model
Unified Community Velocity Model
RELATED RESEARCH

Introduction

The SCEC Community Models (CXM) working group develops, refines and integrates community models describing a wide range of features of the southern California lithosphere and asthenosphere. These features include: elastic and attenuation properties (Community Velocity Model, CVM), temperature (Community Thermal Model, CTM), rheology (Community Rheology Model, CRM), stress and stressing rate (Community Stress Model, CSM), deformation rate (Community Geodetic Model, CGM), and fault geometry (Community Fault Model, CFM). The ultimate long-term goal of the CXM working group is to provide an internally consistent suite of models that can be used together to simulate seismic phenomena in southern California.

Research Priorities

The SCEC research goals involve continued refinement of existing community models (CFM, CVM, CSM, CGM), development of new community models (CTM and CRM), and integration of the models into a self-consistent suite. Objectives also include quantification of uncertainties and development of techniques for propagating uncertainties from observations through community model development to simulation predictions.

Community Fault Model (CFM)

  The CFM is an object-oriented three-dimensional geometric representation of more than 820 fault objects in southern California and adjacent offshore basins for which Quaternary activity has been established (or is deemed probable) and that are considered capable of producing moderate to large earthquakes. The CFM provides triangulated surface representations (t-surfs) that are defined based on surfaces traces, seismicity, seismic reflection profiles, wells, and geologic cross sections and models. The CFM is suitable for use in wide range of fault-related research projects.

Community Geodetic Model (CGM)

  The Community Geodetic Model (CGM) is being developed by the SCEC community to assist in the understanding of the interseismic, coseismic, postseismic, and hydrologic processes associated with the earthquake cycle along the complex fault network of the Southern San Andreas system. The CGM includes time series and velocities from both GPS and InSAR based observations as well as consensus strain rate products.

Community Rheology Model (CRM)

  The SCEC Community Rheology Model (CRM) is a rheological description of the southern California lithosphere, based on an ongoing synthesis of geophysical and geological data.  It comprises three main ingredients: a community thermal model (CTM), a 3D geologic framework (GF), and constitutive relationships applicable to low- and high-strain (shear zone) settings. The CRM is currently under development and a preliminary version is anticipated for release in 2019.

Community Stress Model (CSM)

  The goal of the Community Stress Model (CSM) is to provide the SCEC community with a suite of models and constraints on the stress and stressing rate in the southern California lithosphere.  The CSM consists of multiple different models of stress and stressing rate, based on different types of data, methodology, and assumptions. The models are available in a standardized format on a uniform grid, along with the relevant metadata.

Community Thermal Model (CTM)

  The Community Thermal Model (CTM) provides average 1D steady-state geotherms from the surface to 100 km for 13 distinct Heat Flow Regions (HFR). Within each HFR the measured Surface Heat Flow (SHF) is sensibly constant. Geotherms are constrained by the SHF, bounds on upper crustal radiogenic heat production, seismically estimated Lithosphere Asthenosphere Boundary (LAB) depth, the dry and saturated asthenosphere solidi, and lava and xenolith P/T constraints when available. In several regions, steady-state models are not appropriate and transient models are used. In others, only bounds on geotherms are available.

Community Velocity Model (CVM)

  The CVMH is composed of detailed basin velocity descriptions that are based on tens of thousands of direct velocity measurements and incorporate the locations and displacements of major fault zones that influence basin structure. These basin descriptions are used to develop tomographic models of crust and upper mantle velocity structure, which are subsequently iterated and improved using 3D waveform adjoint tomography. A geotechnical layer (GTL) based on Vs30 measurements and consistent with the underlying velocity descriptions is also included as an optional model component for specific applications via the UCVM.

Unified Community Velocity Model (UCVM)

  The Unified Community Velocity Model (UCVM) software framework provides access to detailed information about earth properties, namely P‐ and S‐wave velocities and density, on regional scales for use by earth scientists, civil engineers, computational scientists, and other groups. The UCVM software allows users to query several existing seismic velocity models, and it provides standard methods for tri-linear interpolation, for calculating Vs30 from models, for meshing, and for combining models.