Our research is in: (i) earthquake strong ground motion for engineering applications, and (ii) earthquake response of man-made structures, aiming to improvement of the seismic design procedures and earthquake risks reduction. It is interdisciplinary, and covers a wide range of topics, such as:  earthquake source mechanism, seismic wave propagation, site and propagation path effects on strong ground motion, prediction of strong ground motion for design (peak amplitudes, duration, and spectral characteristics…), probabilistic seismic hazard assessment, strong motion recording and data processing, soil-structure interaction, structural identification and health monitoring using ambient noise and forced vibrations, effects of various realistic representations of strong ground motion on structures.  We operate the Los Angeles and Vicinity Strong Motion Network, the first urban strong motion network (installed in 1979/80), which has contributed valuable data for numerous engineering and seismological studies.  We also maintain and develop equipment and processing methods for ambient vibration testing of full-scale structures.  The group was formed in 1976 when Prof. M.D. Trifunac joined the Civil Engineering faculty.