Advanced Site Monitoring and Characterization of Site Dynamic Properties

This paper reports on an ongoing research program to develop a capability to: (1) measure cyclic and permanent displacements of field sites, and (2) characterize and estimate the three-dimensional in situ dynamic properties (at low and large strains) of sites for strata ranging from ground surface to a depth of about 30 m. A number of shape-acceleration arrays (SSA) have been installed at the NEES Wildlife Refuge area to monitor the site low-strain response as well as earthquake induced liquefaction, permanent deformation and lateral spreading. This array provides accurate dense measurements of permanent three-dimensional displacements along with three-dimensional accelerations. The installed array recorded moderate site accelerations during the M_L=7.2 Baja California earthquake of April 04, 2010. This paper presents: (1) preliminary one-dimensional analyses of the recorded Wildlife Refuge site response during this earthquake, and (2) an overview of a new multidimensional data reduction and identification technique for a systematic advanced site characterization.