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Using cluster analysis to organize and explore regional GPS velocities

January 1, 2012

Cluster analysis offers a simple visual exploratory tool for the initial investigation of regional Global Positioning System (GPS) velocity observations, which are providing increasingly precise mappings of actively deforming continental lithosphere. The deformation fields from dense regional GPS networks can often be concisely described in terms of relatively coherent blocks bounded by active faults, although the choice of blocks, their number and size, can be subjective and is often guided by the distribution of known faults. To illustrate our method, we apply cluster analysis to GPS velocities from the San Francisco Bay Region, California, to search for spatially coherent patterns of deformation, including evidence of block-like behavior. The clustering process identifies four robust groupings of velocities that we identify with four crustal blocks. Although the analysis uses no prior geologic information other than the GPS velocities, the cluster/block boundaries track three major faults, both locked and creeping.

Publication Year 2012
Title Using cluster analysis to organize and explore regional GPS velocities
DOI 10.1029/2012GL052755
Authors Robert W. Simpson, Wayne Thatcher, James C. Savage
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70042784
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center; Geology, Minerals, Energy, and Geophysics Science Center