[G01-5] Regional reference frames and networks I

[G01-5-05] SHRF16: A Stable Houston Reference Frame for Faulting and Subsidence Study in the Houston Metropolitan Area, Texas, U.S.A.

^○Guoquan Wang, Timothy Kearns, Hanlin Liu, Eleanor Dietz, Vasilios Tsibanos (University of Houston, Houston, U.S.A.)

The greater Houston is one of the fastest-growing metropolitan areas in the United States. More than 150 historically active faults have been identified in the greater Houston area. Accumulated subsidence of over 4 meters during the past century has been observed in a large area of southeast Houston. Subsidence and faulting have caused moderate to severe damage to hundreds of residential, commercial, and industrial structures year by year in the Houston area. GPS technology had been employed in subsidence monitoring in the Houston area since the late 1980s. A dense GPS network with over 180 stations has been established in the Houston metropolitan area through a joint effort by the government, academic, and industry communities. One major consideration in determining the magnitude and velocity of ground displacement over time using GPS, particularly for horizontal ground deformations, is the selection of reference frames. GPS initially provides positioning with respect to a global reference frame. All sites are moving with respect to a global reference frame and site velocities are dominated by secular tectonic plate drifts. A local reference frame is needed to precisely interpret site specific ground deformations over time and space. In this study, we established a Stable Houston Reference Frame using public-available long-term (over 10 years) GPS observations as of 2016. Ten CORS adjacent to the Houston metropolitan area were used as common points (reference stations) to align SHRF16 with IGS08 at epoch 2012.0. The realization of SHRF16 is defined in terms of a Helmert transformation from the global reference frame IGS08. The main results from this study are the 14 parameters for reference frame transformation from IGS08 to SHRF16 and current subsidence contour map (2005 to 2016) in the Houston metropolitan area. SHRF16 will be incrementally improved and be synchronized with the update of IGS reference frame.