HR: 08:00h
AN: G51D-01    [Abstracts]
TI: Detection of time-varying deformation signals in continuous GPS data
AU: * Murray, J R
EM: jrmurray@usgs.gov
AF: US Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, CA 94025 United States
AB: With increasingly large networks of continuous GPS receivers like the Plate Boundary Observatory, the need is clear for an automated way to screen the data for evidence of temporally varying deformation. An automated method will not only reduce the burden on network operators but also introduce an objective way of analyzing time series in order to detect a subtle signal that may not be discernable by eye. Several factors complicate the detection of such signals. (1) The potential source geometry is unknown. (2) The spatial distribution of stations is irregular. (3) The data are contaminated by time-varying noise sources that may mimic transient deformation. Methods have previously been developed to extract and model transient deformation signals in the context of a known deformation source by exploiting the spatial coherence of a source signal and the spatial incoherence of local time-varying noise. In contrast, this work is focused on development of an analysis tool that will exploit the spatial coherence of deformation signals independent of any assumed model geometry. Several approaches have been explored including the use of splines, principal mode analysis, rate-change detection in time series, and weighted averages of neighboring station displacements. The varying geometry and station density of existing networks, and the expected range in the source complexity and temporal character of transient signals suggest using a hierarchy of detection methods. In such an approach, initial analyses will flag areas for further examination. Ultimately, once the geographic location of a potential signal has been refined, source-specific modeling can be pursued. Application of these approaches using time series from SCIGN, PANGA, and GEONET and a range of input synthetic transient signals illustrates the strengths and limitations of these methods in detecting and characterizing aseismic transients.
DE: 1206 Crustal movements--interplate (8155)
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting