A long (similar to 15 km) and narrow (similar to 4 km) offshore positive temperature anomaly (similar to 1.7 degrees C) is observed in the Landsat Thematic Mapper (TM) thermal infrared (TIR) image acquired the day following the large Izmit earthquake (Mw 7.4) of 17 August 1999, in eastern Marmara Sea, Turkey. The earthquake was generated along the North Anatolian Fault, which ruptured for about 150km, and the anornaly formed at the western termination of this rupture. Discussions of this anomaly may develop by processes different than the seismic activity and considerations on fault geometry and sea bathymetry characteristics suggest that the anomaly may result from aftershock activity near the western end of the earthquake fault. The formation of the anomaly requires the addition of a large quantity of hot waters to the sea. The ascent to the sea bottom of fault-driven hot fluids (seismic pumping) and formation of thermal plumes may be the processes by which the sea surface temperature increased. Recent works and the present study suggest that TIR data analysis may be used as a toot in seismological studies.