The Whittier Narrows earthquake (1987) and the Loma Prieta earthquake (1989), collectively shook 9,286 unreinforced masonry buildings (UMB) in Modified Mercalli Intensity zone VI and higher. Damage was reported on 599 of the buildings which had been retrofitted prior to the two earthquakes. This provided a significant data base for study. Certain existing building rehabilitation schemes for unreinforced masonry structures are becoming standards for California and models for the rest of the U.S. in earthquake hazard mitigation efforts. The main goal of this research effort is to provide an informative data base, technical design alternatives, and legal analysis for municipalities in various seismic zones to use in selecting rehabilitation measures. It will also guide design professionals as to their rehabilitation responsibilities and potential liabilities.
