Sustainable Cities, a Regional Seismic Scenario, and the 6-23-2001 Arequipa Peru Earthquake

Abstract

From 1998 to early 2001, fifteen Peruvian cities developed and enforced ordinances on land use, channeling urban expansion and population growth into areas that microzonation investigations had determined to be safe. This process took place as part of the “Sustainable Cities, First Stage”—SC-1S. The hazard maps, land use planning, and priority projects to reduce the vulnerability of the city facilities were unanimously approved by the communities involved and all local government council members. Investigations into the effects of the Arequipa, Peru, earthquake of June 23, 2001, were performed to take advantage of this unique opportunity to find out just how useful preevent studies are in reducing disasters. In this case a regional seismic scenario (RSS) had been constructed from 1992 to 1995 for Peru’s southwestern region. The macroseismic area of the June 2001 event overlapped substantially with this RSS. The other main objective of the comparison between the RSS and the effects of the real event was to validate the application of hazard maps in land use planning to reduce losses caused by intense natural events. It was estimated that relatively low acceleration on rock occurred over extensive areas, but this was greatly amplified on soft water-saturated soil, unstable slopes, and uncompacted filled soil. As those were the places where the RSS assumed that the earthquake damage would be severe, the predicted locations of the RSS coincided with the locations that were the worst hit by the June 2001 earthquake. In this paper, comparison is made between the 1992–1995 RSS and the effects of the Arequipa June 2001 earthquake, to verify how useful predisaster investigations are and to validate the seismic hazard maps employed in land-use planning for disaster reduction, which have been widely applied in Peru in the SC-1S program over the past three years.