SCEC Award Number 11078 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Transient Detection using SCIGN and PBO data
Name Organization
Thomas Herring Massachusetts Institute of Technology Robert King Massachusetts Institute of Technology
Other Participants Kang Hyeun Ji
SCEC Priorities A5, A2, C SCEC Groups Geodesy, CDM, SHRA
Report Due Date 02/29/2012 Date Report Submitted N/A
Project Abstract
We have generated results in three major areas during the SCEC3 period. Most of our results have been generated in trying to measure, understand and model transient signals seen in geodetic data. We have also generated results for a consensus Western United States velocity field for use in the Unified California Earthquake Rupture Forecast (UCERF3) hazard model and we have steadily worked at incorporating results from the Southern California Integrated GPS Network (SCIGN) GPS network into the Plate Boundary Observatory (PBO) analysis. Our major results in transient signal detection were demonstration of large-scale postseismic seismic deformation from the Hector mine earthquake, detection of a volcanic inflationary event on Akutan Volcano, and the analysis of hydrologically driven geodetic signals in the San Gabriel Valley. We also assisted in the final preparation and publication of the crustal motion model (CMM4) that appeared in J. Geophys. Res. in 2011.
Intellectual Merit Our main contributions to SCEC have been in making available results from our combination of SCIGN and PBO GPS data, crustal motion models and tectonic velocity fields for Southern California and the Western United States for use in the unified California earthquake rupture forecast models, and how development and discussions of transient signal detection.
Broader Impacts Our publications on the nature of post-seismic deformation and the processes that generate these signals, transient signal detection on the Akutan volcano and in the San Gabriel Valley have demonstrated to the scientific community the potential applications of the methodologies and data being developed at SCEC.
Exemplary Figure Figure H2: Spatial (left) patterns of the first principal component (PC) from the horizontal components (black; eigenvalue 94.1% and chi-square per degrees-of-freedom ) and the vertical components (red; eigenvalue 93.5% and ) of 11 sites (solid triangles) in the San Gabriel Valley located in Southern California (inset). The scale arrow (left bottom) indicates 10 % of the PC amplitude in millimeters. The spatial pattern shows an expansion and uplift of the basin and the temporal pattern is highly correlated with the changes in groundwater levels above mean sea level (blue curve) measured at the Baldwin Park Key Well (blue square). The left frame shows the time series after projection of the data onto the principal axes of horizontal surface deformation associated with the 2005 rain event. The projected time series is in a gray scale (color bar on the right) with the number of components (total 22 components from 11 stations) available as a function of time. The error bars (gray) were obtained by propagating the formal errors onto the principal axes. Also shown are the principal component time series (red; see Figure 1) and the changes in groundwater levels (blue; scale shown in 5 m vertical bar in the middle) at the Baldwin Park Key Well. The water levels were adjusted to the projected time series in a least squares sense by removing a linear trend of -0.75 ± 0.04 m/yr and scaling the water levels by 1.51 ± 0.04 mm/m. The 2005 rain event is not the only one that can now be seen in the horizontal motions of the GPS sites. The projected time series and the water level changes are highly correlated with a correlation coefficient of 0.96 ± 0.01.