New Crustal Deformation Velocity Map Incorporates More Data

The SCEC Crustal Deformation Working Group (Group E) recently announced the availability of a new version of the Crustal Deformation Velocity Map for southern California.

The entire contents of the new release version are available on theWeb at: WWW.SCECDC.SCEC.ORG/GROUP_E/RELEASE.V2/

This new solution results from an analysis of nearly all the EDM,VLBI, and SCEC-archived GPS data (both survey and continuous mode) acquired for southern California between 1970 and 1997.

The maps and accompanying tables include new estimates of the horizontal velocities for 363 stations. Uncertainties in theseestimates are less than 5 mm/yr. For stations close to the Landersepicenter, we provide estimates of both the pre- and post-Landers velocities.

Important differences between Release 2.0 and Release 1.0 (October 1996) of the map are (1) the direct use of the VLBI data and (2) the addition of several additional sets of GPS data:

· Continuous GPS observations since 1992

· Post-Landers surveys of the epicentral region

· A 1992 survey of about 60 stations in and near Los Angeles

· A 1997 resurvey of about 60 stations in the vicinity of the

southern San Andreas fault and Salton Trough

These additions incorporated into the new solution have added 76 stations to the map and have reduced two-thirds of the station velocity uncertainties to about 1 mm/yr.

A discussion of planned work on improving the velocity map is in the group's 1997-1998 annual report:

WWW-SOCAL.WR.USGS.GOV/HUDNUT/SCEC/SCEC_GROUP_E.HTML