Initial Geotechnical Observations of the November 12, 1999, Düzce Earthquake

A report of the Turkey-US geotechnical earthquake engineering reconnaissance team

A. Ansal, J. P. Bardet, A. Barka, M. B. Baturay, M. Berilgen, J. Bray, O. Cetin, L. Cluff, T. Durgunoglu, D. Erten, M. Erdik, I. M. Idriss, T. Karadayilar, A. Kaya,  W. Lettis, G. Olgun, W. Paige, E. Rathje, C. Roblee, J. Stewart, and D. Ural

November 26, 1999

Outline

• Summary
• Initial reconnaissance
• Acknowledgments

Summary

On November 12, 1999 at 6:57 PM (local time), a magnitude Mw 7.2 earthquake struck the Düzce-Bolu area of Turkey, 70 km east of Adapazari and 170 km northwest of Ankara. The earthquake epicenter is located near the town of Düzce, on the eastern end of the fault that is believed to have ruptured during the August 17, 1999 Mw = 7.4 event. The November 12, 1999 earthquake epicenter is located at 40.77N 31.15E, which is about 110 km east of the magnitude 7.4 main shock on August 17 which killed over 17,000 people and injured another 50,000.

On November 26, 1999, preliminary estimates of casualties and injured are 755 and 4948, respectively. The material damage is extensive. 1342 structures have collapsed. A total of 7081 residential and industrial buildings are heavily damaged. Table 1 summarizes the distribution of losses due to the November 12, 1999 earthquake. Most of the losses are located in Düzce, Kaynasli, Bolu and Konuralp. These numbers may change as more information becomes available. Revised estimates can be obtained from http://angora.deprem.gov.tr.

Table 1. Losses due to the November 12, 1999 Düzce Earthquake (as of November 26, 1999)

Initial reconnaissance

This preliminary report summarizes the observations of the Turkey/US geotechnical earthquake reconnaissance team sponsored by the US National Science Foundation and various organizations from Turkey. The report is preliminary as it covers the reconnaissance from November 17 to November 20, 1999. A more comprehensive report will be issued in the future.

The preliminary report is made of seven sections describing the reconnaissance flight from Istanbul to Düzce and the damage in several areas including Düzce, Bolu, Kaynasli, Adapazari, and between Bolu and Düzce. A special section is dedicated to the damage to the Bolu Viaducts and Tunnel. The members of the November 1999 reconnaissance team, who also participated to the reconnaissance of the August 17, 1999, earthquake, are:

• Atilla Ansal, Istanbul Technical University, Istanbul
• Jean-Pierre Bardet, University of Southern California, Los Angeles
• Mehmet Baturay, University of California, Los Angeles
• Jonathan Bray, University of California, Berkeley
• Onder Cetin, University of California, Berkeley
• Turan Durgunoglu, Bogazici University and Zetas Earth Technology Corporation, Istanbul
• Mustafa Erdik, Bogazici University, Istanbul
• Turhan Karadayilar, Zetas Earth Technology Corporation, Istanbul
• Abidin Kaya, Dokuz Eylul University, Izmir
• William Lettis, Lettis and Associates
• William Paige, Pacific Gas and Electric Company, San Francisco
• Elen Rathje, University of Texas, Austin
• Jonathan Stewart, University of California, Los Angeles
• Derin Ural, Middle East Technical University, Ankara

Acknowledgments

We would like to express all our thanks to our Turkish and American colleagues who helped us in our reconnaissance effort and to express our sympathy to those who have suffered from this natural disaster. The financial support of the Earthquake Hazard Mitigation Program of the National Science Foundation is acknowledged.