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Geotechnical Report from June 23, 2001 Peruvian Earthquake

1.0 INTRODUCTION

On June 23, 2001 at 3:33 p.m. (local time), an M8 class earthquake struck near the coast of southern Peru. Various magnitude values have been reported (M_w 8.4 by the Harvard CMT, M_w 8.3 by the USGS, M_w 8.2 by the Earthquake Information Center, Tokyo). The epicenter was located about 175 km west of Arequipa or 595 km southeast of Lima. Based on information from the USGS, the earthquake epicenter is located at 16.14S 73.31W, near the city of Ocoña. The earthquake had a shallow focal depth; however, because a large portion of the plate interface ruptured, it is difficult to estimate a single representative focal depth value. More than thirty significant aftershocks (M_w > 4.0) have been reported through July 7 with the largest having a magnitude of 7.6 on July 7 (USGS 2001). Approximate locations of the epicenter and aftershocks are shown on Figure 1.1 (USGS 2001). The earthquake caused extensive damage in the areas around the cities of Arequipa, Camana, Moquegua, and Tacna. Part of the damage is due to a tsunami wave in the Camana area. As of July 20, 2001, the Civil Defense Institute in Peru (INDECI) reports 80 casualties and 64 missing persons, with an estimated 36,000 homes damaged affecting a total of approximately 223,000 people. (http://www.indeci.gob.pe/)

1.1 Site Reconnaissance

This preliminary report summarizes observations performed between July 8 and July 12, 2001 during the initial reconnaissance effort. The earthquake engineering reconnaissance team sponsored by the U.S. National Science Foundation included the following members:

• – Adrian Rodriguez-Marek, Washington State University
• – Pedro Repetto, URS Corporation
• – Joseph Wartman, Drexel University
• – Dale Baures, URS Corporation
• – Efraín Rondinel, Pontificia Universidad Católica del Perú
• – Jennifer Williams, URS Corporation
• – Jorge Zegarra-Pellanne, Pontificia Universidad Católica del Perú

The team visited and documented sites including major cities, mining facilities and transportation routes. The major cities visited included Tacna, Moquegua, Ilo, Arequipa, Camana, and Ocoña. Mining facilities included the Cerro Verde, Toquepala and Cuajone copper mines. Transportation routes consisted mainly of the roads connecting these sites. Figure 1.2 shows the area covered during this initial reconnaissance visit. It is important to note that the damage reported herein encompasses the cumulative damage of the June 23 mainshock and the subsequent aftershocks. Reports by local residents, however, indicate that most of the damage is attributed to the mainshock.

1.2 Acknowledgements

We would like to express our thanks to all those who supported and facilitated this effort, especially Clifford J. Astill of the National Science Foundation; Oscar Gonzales Rocha, President of Southern Peru Copper; Randy Davenport, General Manager of Sociedad Minera Cerro Verde; Adolfo Gonzales Palma, President of Tacna’s Professional Engineers Society; Martín Vizcarra Cornejo, President of Moquegua’s Professional Engineers Socity; César Ramos Zamora, Head of Region XV of the National System of Highway Maintenance, Eduardo Fierro of Wiss, Janney, Elstner Associates, and Manuel Olcese (Dean of Civil Engineering), Daniel Quiun and Alejandro Muñoz from the Catholic Univeristy of Peru. Names of other individuals who contributed in the reconnaissance efforts will be included in the final version of this report. We would also like to thank the Pacific Earthquake Engineering center for hosting this report. NOTE: All photographs and maps presented at this web site, with the exception of those credited to outside sources, were developed by the authors of this report. Please provide citation: "from Rodriguez-Marek et al., 2001 ­ a NSF sponsored reconnaissance effort" when using materials downloaded from this web report. This material is based upon work supported by the National Science Foundation under Grant No. CMS-0130617.