Adana-Ceyhan earthquake occurred at 4:56 PM local time on 27 June 1998. The epicentral coordinates of the main shock (Ms=6.2) were reported as 36.95 N and 35.31 E, and the focal depth as 23 km which is followed by numerous aftershocks that are shown in Figure 2. The strike direction of the causative Misis fault is in the left lateral sense, with a rupture directivity from Southwest to Northeast toward Ceyhan. Accordingly, earthquake shaking was felt most strongly in Ceyhan (population 100 000) with the evidence of heavy damage in the city (MM intensity VIII). It was also strongly felt and caused damage in the nearest provincial capital Adana (population 1.2 million) and its suburb Yüreğir.
The area shown in Figure 2 has been the scene for many earthquakes in the past. Eight earthquakes with magnitudes between 5.5 and 6.2 occurred during 1907 to 1952, where the last one in 1952 with M=5.6 was very similar to the 1998 event in epicenter and the intensity in the felt area [Gencoğlu et al. 1990].
The Adana-Ceyhan earthquake along the Misis fault triggered several SMA instruments deployed in the area. A
summary of the instrumental recordings are given in Table 1. It is noteworthy that Ceyhan and Karataş Stations
recorded very different ground acceleration peaks despite their similarity in epicentral distance. This difference
may be attributed to two factors. First is the rupture directivity where Ceyhan is in the forward and Karataş is in
the backward of the rupture direction, and the second is the difference in local soil conditions as indicated in Table 1. The notable amplification of horizontal acceleration at Mersin compared to the other stations with similar distances is also related to the difference in local soil conditions.cuoğlu, 1999].
After the 1998 Adana-Ceyhan earthquake [Gülkan, 1998], seismit retrofit works of all 120 moderately damaged R/C residential apartment buildings in Ceyhan have been assigned to METU/EERC. This building stock is composed of 3-9 story buildings, with a total floor area of 220 000 sq m. METU/EERC has coordinated geotechnical and structural engineering consultants in undertaking this task. The retrofit design of all buildings has been completed in June 1999. Technical supervision of construction will also be done by the same organization. This paper reviews seismic and engineering aspects of the Adana-Ceyhan earthquake and summarizes the seismic retrofit works carried out by METU/EERC.