3D Velocity Model:

SCEC Costa Mesa Meeting Summary
R. Clayton, Caltech


Data Sources
	seismicity/relocation
	travel time tomography
	industry reflection data
	waveform modeling
	receiver function analysis
	teleseismic travel times
	LARSE-like experiments
	geologic structure models
	well-log data
	geotechnical (near-surface) data
	surface wave dispersion
	marine profiles
	gravity (for density)

Uses of the Model
	seismicity catalogue locations
	strong motion modeling
	tectonic/stress modeling
	geologic and rheology models

Scale of Model
	regional S. California component
	densification in the greater LA Basin region
	area/fault specific component
	lower crust and upper mantle component

Possible Parameterization of the Model
	3D sampled models (i.e. tomography style)
	rule-based (velocity derived from empirical rules based on
		depth, age and other attributes; Magistrale's model
		is an example of this)
	iso-surface [depth(x,y) for a particular velocity/horizon]
	point/line samples (borehole measurements, 2D refraction lines)

Issues
	model parameterization and construction
	validation - how and with what to test the model
	integrity - how do we keep a master model when various groups
		may be updating it.  How to we add updates that are
		based on alternative parameterizations
	how do we derive specialized version of the model, i.e. smooth
		models for ray tracers, and lower dimensional models
		for surface wave analysis.

Starting Models
	Magistrale's rule based model
	Hauksson's travel time tomography models
	Grave's strong motion waveform model
	Kohler's Upper Mantle model