Reconnaissance of Damage to Historic Monuments in Cairo, Egypt Following the October 12, 1992 Dahshur Earthquake

Keywords: Cairo, Egypt Earthquake, October 12, 1992, Local Soil Conditions, Environmental Deterioration, Dahshur, Egypt Earthquake, October 12, 1992, Historic Monuments, Maintenance, Damage, Historic Preservation, Regional Tectonics, and Groundwater.

Abstract: On October 12, 1992, a moderate earthquake occurred near Dahshur, Egypt, about 20 km south of Cairo. The intensity of ground shaking at historic districts of Cairo was VI to VII using the Modified Mercalli scale and 212 of 560 monuments in Cairo were reportedly damaged although none destroyed. Damage to historic monuments can be generally described as having resulted from the continuous degradation of foundation and structural masonry from environmental effects, especially groundwater, inadequate lateral structural resistance, and the subsequent imposition of light to moderate earthquake forces. Other large earthquakes have affected old monuments in Cairo, but the recent earthquake may have caused a disproportionate amount of damage because of wide-spread poor structural conditions. This study provides specific examples of how monuments ranging from 80 to about 1,500 years in age, in various conditions, respond to near-field motions from a moderate-magnitude earthquake and helps to define problems that research studies can solve. It also provides strong evidence that a preservation strategy be adopted for historic monuments in Cairo that embraces scientific and engineering knowledge to understand these monuments and propose the least invasive repair and retrofit procedures.